Abstract:
An electrochemical storage device comprises a plurality of layer electrodes each including a first charged sector and a second charged sector. The plurality of layer electrodes are assembled with respect to each other such that the first charged sector of a first plate of the plurality of layer electrodes is laid below the second charged sector of a second plate of the plurality of layer electrodes located immediately above the first plate. The charges of the first charged sectors of the first and second plates have a first sign and the charges of the second charged sectors of the first and second plates have a second sign that is opposite the first sign. The device also comprises a separator sector located, and enabling ionic charge exchange, between the first charged sector of the first plate and the second charged sector of the second plate.

Description:
RELATED APPLICATIONS 
     This application is a continuation in part of application Ser. No. 13/350,686, filed Jan. 13, 2012, entitled “Lead-acid battery design having versatile form factor”, which incorporated by reference the entire disclosure of the concurrently filed U.S. application Ser. No. 13/350,505 entitled, “Improved Substrate for Electrode of Electrochemical Cell.” 
    
    
     TECHNICAL FIELD 
     Embodiments of the present disclosure relate generally to electrochemical cells. More particularly, embodiments of the present disclosure relate to a design of a lead-acid electrochemical cell. 
     BACKGROUND 
     Lead-acid electrochemical cells have been commercially successful as power cells for over one hundred years. For example, lead-acid batteries are widely used for starting, lighting, and ignition (SLI) applications in the automotive industry. 
     As an alternative to lead-acid batteries, nickel-metal hydride (“Ni-MH”) and lithium-ion (“Li-ion”) batteries have been used for hybrid and electric vehicle applications. Despite their higher cost, Ni-MH and Li-ion electro-chemistries have been favored over lead-acid electrochemistry for hybrid and electric vehicle applications due to their higher specific energy and energy density compared to lead-acid batteries. 
     While lead-acid, Ni-MH, and Li-ion batteries have each experienced commercial success, conventionally, each of these three types of chemistries have been limited to certain applications.  FIG. 18  shows a Ragone plot of various types of electrochemical cells that have been used in automotive applications, depicting their respective specific powers and specific energies compared to other technologies. 
     Lead-acid battery technology is low-cost, reliable, and relatively safe. Certain applications, such as complete or partial electrification of vehicles and back-up power applications, require higher specific energy than traditional SLI lead-acid batteries deliver. As shown in Table 1, lead-acid batteries suffer from low specific energy due to the weight of the components. Thus, there remains a need for low-cost, reliable, and relatively safe electrochemical cells for various applications that require high specific energy, including certain automotive and back-up power applications. 
     Lead-acid batteries have many advantages. First, they are a low-cost technology capable of being manufactured in any part of the world. Accordingly, production of lead-acid batteries can be readily scaled-up. Lead-acid batteries are available in large quantities in a variety of sizes and designs. In addition, they deliver good high-rate performance and moderately good low- and high-temperature performance. Lead-acid batteries are electrically efficient, with a turnaround efficiency of 75 to 80%, provide good “float” service (where the charge is maintained near the full-charge level by trickle charging), and exhibit good charge retention. Further, although lead is toxic, lead-acid battery components are easily recycled. An extremely high percentage of lead-acid battery components (in excess of 95%) are typically recycled. 
     Lead-acid batteries suffer from certain disadvantages as well. They offer relatively low cycle life, particularly in deep-discharge applications. Due to the weight of the lead components and other structural components needed to reinforce the plates, lead-acid batteries typically have limited energy density. If lead-acid batteries are stored for prolonged periods in a discharged condition, sulfation of the electrodes can occur, damaging the battery and impairing its performance. In addition, hydrogen can be evolved in some designs. 
     In contrast to lead-acid batteries, Ni-MH batteries use a metal hydride as the active negative material along with a conventional positive electrode such as nickel hydroxide. Ni-MH batteries feature relatively long cycle life, especially at a relatively low depth of discharge. The specific energy and energy density of Ni-MH batteries are higher than for lead-acid batteries. In addition, Ni-MH batteries are manufactured in small prismatic and cylindrical cells for a variety of applications and have been employed extensively in hybrid electric vehicles. Larger size Ni-MH cells have found limited use in electric vehicles. 
     The primary disadvantage of Ni-MH electrochemical cells is their high cost. Li-ion batteries share this disadvantage. In addition, improvements in energy density and specific energy of Li-ion designs have outpaced advances in Ni-MH designs in recent years. Thus, although nickel metal hydride batteries currently deliver substantially more power than designs of a decade ago, the progress of Li-ion batteries, in addition to their inherently higher operating voltage, has made them technically more competitive for many hybrid applications that would otherwise have employed Ni-MH batteries. 
     Li-ion batteries have captured a substantial share not only of the secondary consumer battery market but a major share of OEM hybrid battery, vehicle, and electric vehicle applications as well. Li-ion batteries provide high-energy density and high specific energy, as well as long cycle life. For example, Li-ion batteries can deliver greater than 1,000 cycles at 80% depth of discharge. 
     Li-ion batteries have certain advantages. They are available in a wide variety of shapes and sizes, and are much lighter than other secondary batteries that have a comparable energy capacity (both specific energy and energy density). In addition, they have higher open circuit voltage (typically ˜3.5 V vs. 2 V for lead-acid cells). In contrast to Ni—Cd and, to a lesser extent, Ni-MH batteries, Li-ion batteries suffer no “memory effect,” and have much lower rates of self discharge (approximately 5% per month) compared to Ni-MH batteries (up to 20% per month). 
     Li-ion batteries, however, have certain disadvantages as well. They are expensive. Rates of charge and discharge above 1 C at lower temperatures are challenging because lithium diffusion is slow and it does not allow for the ions to move fast enough. Further, Li-ion batteries use liquid electrolytes to allow for faster diffusion rates, which results in formation of dendritic deposits at the negative electrode, causing hard shorts and resulting in potentially dangerous conditions. Liquid electrolytes also form deposits (referred to as an SEI layer) at the electrolyte/electrode interface, that can inhibit electron transfer, indirectly causing the cell&#39;s rate capability and capacity to diminish over time. These problems can be exacerbated by high-charging levels and elevated temperatures. Li-ion cells may irreversibly lose capacity if operated in a float condition. Poor cooling and increased internal resistance cause temperatures to increase inside the cell, further degrading battery life. Most important, however, Li-ion batteries may suffer thermal runaway, if overheated, overcharged, or over-discharged. This can lead to cell rupture, exposing the active material to the atmosphere. In extreme cases, this can cause the battery to catch fire. Deep discharge may short-circuit the Li-ion cell, causing recharging to be unsafe. 
     To manage these risks, Li-ion batteries are typically manufactured with expensive and complex power and thermal management systems. In a typical Li-ion application for a hybrid vehicle, two-thirds of the volume of the battery module may be given over to collateral equipment for thermal management and power electronics and battery management, dramatically increasing the overall size and weight of the battery system, as well as its cost. 
     In addition to the differing advantages and disadvantages of lead-acid, Ni-MH and Li-ion batteries, the specific energy, energy density, specific power, and power density of these three electro-chemistries vary substantially. Typical values for systems used in HEV-type applications are provided in Table 1 below. 
     
       
         
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Electro-chemistry 
                 Specific Energy 
                 Energy Density 
                 Specific Power 
               
               
                 Type 
                 (Whr/kg) 
                 (Whr/l) 
                 (W/kg) 
               
               
                   
               
             
             
               
                 Lead-Acid 1   
                  30-50 Whr/kg 
                  60-75 Whr/l 
                 100-250 W/kg 
               
               
                 Nickel Metal 
                 65-100 Whr/kg 
                 150-250 Whr/l 
                 250-550 W/kg 
               
               
                 Hydride 
               
               
                 (Ni-MH) 2   
               
               
                 Lithium-Ion 
                 up to 131 Whr/kg 
                     250 Whr/l 
                 up to 2,400 W/kg 
               
               
                 (Li-ion) 3   
               
               
                   
               
               
                   1 http://en.wikipedia.org/wiki/Lead_acid_battery, accessed Jan. 11, 2012. 
               
               
                   2 Linden, David, ed., Handbook of Batteries, 3 rd  Ed. (2002). 
               
               
                   3 http://info.a123systems.com/data-sheet-20ah-prismatic-pouch-cell, accessed Jan. 11, 2012. 
               
             
          
         
       
     
     Although both Ni-MH and Li-ion battery chemistries have claimed a substantial role in hybrid and electrical vehicles, both chemistries are substantially more expensive than lead-acid batteries for vehicular propulsion assist. The present inventors believe that the embodiments of the present disclosure can substantially improve the capacity of lead-acid batteries to provide a viable, low-cost alternative to Ni-MH and Li-ion electro-chemistries in all types of hybrid and electrical vehicle applications. 
     In particular, certain applications have proved difficult for Ni-MH and Li-ion batteries, such as certain automotive and standby power applications. Standby power application requirements have gradually been raised. The standby batteries of today have to be truly maintenance free, have to be low-cost, have long cycle-life, have low self-discharge, be capable of operating at extreme temperatures, and, finally, should have high specific energy and high specific power. Emerging smart grid applications to improve energy efficiency require high power, long life, and lower cost for continued growth in the market place. 
     Automobile manufacturers have encountered substantial consumer resistance in launching fleets of electric vehicles and hybrid vehicles, due to the increased cost of these vehicles relative to conventional automobiles powered by an internal combustion engine (“ICE”). Environmental and energy independence concerns have exerted greater pressures on manufacturers to offer cost-effective alternatives to internal combustion engine-powered vehicles. Although hybrids and electric vehicles can meet that demand, they typically rely on subsidies to defray the higher cost of the energy storage systems. 
     Table 2 below compares the application of various battery electro-chemistries and the internal combustion engine (ICE) and their current roles in certain automotive applications. As used in Table 2, “SLI” means starting, lighting, ignition; “HEV” means hybrid electric vehicle; “PHEV” means plug-in hybrid electric vehicle; “EREV” means extended range electric vehicle; and “EV” means electric vehicle. 
     
       
         
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                   
                   
                 Power 
                   
                 Mild 
                   
                   
                   
                   
               
               
                   
                 SLI 
                 Start/Stop 
                 Assist 
                 Regeneration 
                 Hybrid 
                 HEV 
                 PHEV 
                 EREV 
                 EV 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Pb- 
                 ✓ 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Acid 
               
               
                 Ni- 
                   
                   
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
               
               
                 MH 
               
               
                 Li- 
                   
                   
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
               
               
                 ion 
               
               
                 ICE 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
               
               
                   
               
             
          
         
       
     
     As shown in Table 2, there remains a need for specific applications in which partial electrification of the vehicle may provide environmental and energy efficiency advantages, without the same level of added costs associated with hybrid and electric vehicles using Ni-MH and Li-ion batteries. Even more specifically, there is a need for a low cost, energy efficient battery in the area of start/stop automotive applications. 
     Specific points in the duty cycle of an internal combustion engine entail far greater inefficiency than others. Internal combustion engines operate efficiently only over a relatively narrow range of crankshaft speeds. For example, when the vehicle is idling at a stop, fuel is being consumed with no useful work being done. Idle vehicle running time, stop/start events, power steering, air conditioning, or other power electronics component operation entail substantial inefficiencies in terms of fuel economy, as do rapid acceleration events. In addition, environmental pollution from a vehicle at these “start-stop” conditions is far worse than from a running vehicle that is moving. The partial electrification of the vehicle in relation to these more extreme operating conditions has been termed a “micro” or “mild” hybrid application, including start/stop electrification. Micro- and mild-hybrid technologies are unable to displace as much of the power delivered by the internal combustion engine as a full hybrid or electric vehicle. Nonetheless, they may be able to substantially increase fuel efficiency in a cost-effective manner without the substantial capital expenditure associated with full hybrid or full electric vehicle applications. 
     Conventional lead-acid batteries have not yet been able to fulfill this role. Conventional lead-acid batteries have been designed and optimized for the specific application of SLI operation. The needs of a mild hybrid application are different. A new process, design, and production process need to be developed and optimized for the mild hybrid application. 
     One need for a mild hybrid application is low-weight battery. Conventional lead-acid batteries are relatively heavy. This causes the battery to have a low specific energy due to the substantial weight of the lead components and other structural components that are necessary to provide rigidity to the plates. SLI lead-acid batteries typically have thinner plates, providing increased surface area needed to produce the power necessary to start the engine. But the grid thickness is limited to a minimum useful thickness because of the casting process and the mechanics of the grid hang. The minimum grid thickness is also determined on the positive electrode by corrosion processes. Positive plates are rarely less than 0.08″ (main outside framing wires) and 0.05″ on the face wires because of the difficulties of casting at production rates and, more importantly, concern over poor cycle-life issues. These parameters limit power. Lead-acid batteries designed for deeper discharge applications (such as motive power for forklifts) typically have heavier plates to enable them to withstand the deeper depth of discharge in these applications. 
     In addition, in typical lead-acid batteries, the active material is usually formed as a paste that is applied to the grid in order to form the plates as a composite material. Although the paste adheres well to itself, it does not adhere well to the grid materials because of paste shrinkage issues. This requires the use of grids that are more substantial and contain additional structural components to help support the active material, which, in turn, puts an extra weight burden on the cell. 
     Further, during the manufacture of conventional lead-acid batteries, the components are subjected to a number of mechanical stresses. Pasting active material onto the grid can stress the latticework of the grid. Expanded metal grids are lighter than cast grids, yet, the formation of the expanded grid itself introduces stress at each of the nodes of the expanded grid. These various structural materials, being subjected to substantial mechanical stresses during electrode pasting, handling, and cell operation, tend to corrode more readily in the acid-oxidizing environment of the battery after activation, especially when thin plates are used to increase power. 
     For example, cast and expanded metal grids have non-uniform stress during the life of the battery due to the molar volume change of converting the lead metal to PbO 2 . This volume change of the corrosion product puts huge stress on the grids in a non-uniform manner because of the irregular cross-sectional shapes of the grid wires in cast and expanded metals. 
     Another need for a mild hybrid application is that rechargeable batteries should be able to be charged and discharged with less than 0.001% energy loss at each cycle. This is a function of the internal resistance of the design and the overvoltage necessary to overcome it. The reaction should be energy-efficient and should involve minimal physical changes to the battery that might limit cycle life. Side chemical reactions that may deteriorate the cell components, cause loss of life, create gaseous byproducts, or loss of energy should be minimal or absent. In addition, a rechargeable battery should desirably have high specific energy, low resistance, and good performance over a wide range of temperatures and be able to mitigate the structural stresses caused by lattice expansion. When the design is optimized for minimum resistance, the charge and discharge efficiency will dramatically improve. 
     Lead-acid batteries have many of these characteristics. The charge-discharge process is essentially highly reversible. The lead-acid system has been extensively studied and the secondary chemical reactions have been identified. And their detrimental effects have been mitigated using catalyst materials or engineering approaches. Although its energy density and specific energy are relatively low, the lead-acid battery performs reliably over a wide range of temperatures, with good performance and good cycle life. A primary advantage of lead-acid batteries remains their low-cost. 
     A typical lead-acid electrochemical cell uses lead dioxide as an active material in the positive plate and metallic lead as the active material in the negative plate. These active materials are formed in situ. Typically, a charged positive electrode contains PbO 2 . The electrolyte is sulfuric acid solution, typically about 1.2 specific gravity or 37% acid by weight. The basic electrode process in the positive and negative electrodes in a typical cycle involves formation of PbO 2 /Pb via a dissolution-precipitation mechanism, causing non-uniform stresses within the positive electrode structure. The first stage in the discharge-charge mechanism is a double-sulfate formation reaction. Sulfuric acid in the electrolyte is consumed by discharge, producing water as the product. Unlike many other electrochemical systems, in lead-acid batteries the electrolyte is itself an active material and can be capacity-limiting. 
     In conventional lead-acid batteries, the major starting material is highly purified lead. Lead is used for the production of lead oxides for conversion first into paste and ultimately into the lead dioxide positive active material and sponge lead negative active material. Pure lead is generally too soft to be used as a grid material because of processing issues, except in very thick plates or spiral-wound batteries. Lead is typically hardened by the addition of alloying elements. Some of these alloying elements are grain refiners and corrosion inhibitors but others may be detrimental to grid production or battery performance generally. One of the mitigating factors in the corrosion of lead/lead grids is the high hydrogen over-potential for hydrogen evolution on lead. Since most corrosion reactions are accompanied by hydrogen evolution as the cathode reaction, reduced hydrogen evolution may inhibit anodic corrosion as well. 
     The purpose of the grid is to form the support structure for the active materials and to collect and carry the current generated during discharge from the active material to the cell terminals. Mechanical support can also be provided by non-metallic elements such as polymers, ceramics, and other components. But these components are not electrically conductive. Thus, they add weight without contributing to the specific energy of the cell. 
     Lead oxide is converted into a dough-like material that can be fixed to grids forming the plates. The process by which the paste is integrated into the grid is called pasting. Pasting can be a form of “ribbon” extrusion. The paste is pressed by hand trowel, or by machine, into the grid interstices. The amount of paste applied is regulated by the spacing of the hopper above the grid or the type of troweling. As plates are pasted, water is forced out of the paste. 
     The typical curing process for SLI lead-acid plates is different for the positive and negative plates. Typically water is driven off the plate in a flash dryer until the amount of water remaining in the plate is between about 8 to 20% by weight. The positive plate is hydro-set at low temperature (&lt;55 C+/−5 C) and high humidity for 24 to 72 hours. The negative plate is hydro-set at about the same temperature and humidity for 5 to 12 hours. The negative plate may be dried to the lower end of the 8 to 20% range and the positive plate to the upper end of the range. More recently, manufacturers use curing ovens where temperature and humidity are more precisely controlled. In the conventional process steps, the “hydro-set process” causes shrinkage of the “paste” active material that, in turn, causes it to break away from the grid in a non-uniform manner. The grid metal that is exposed is corroded preferentially and, since it is not in contact locally with the active material, results in increased resistance as well as formation, and life issues. 
     A simple cell consists of one positive and one negative plate, with one separator positioned between them. Most practical lead-acid electrochemical cells contain between 3 and 30 plates with separators between them. Leaf separators are typically used, although envelope separators may be used as well. The separator electrically insulates each plate from its nearest counter-electrode but must be porous enough to allow acid transport in or out of the plates. 
     A variety of different processes are used to seal battery cases and covers together. Enclosed cells are necessary to minimize safety hazards associated with the acidic electrolyte, potentially explosive gases produced on overcharge, and electric shock. Most SLI batteries are sealed with fusion of the case and cover, although some deep-cycling batteries are heat sealed. A wide variety of glues, clamps, and fasteners are also well-known in the art. 
     Typically, formation is initiated after the battery has been completely assembled. Formation activates the active materials. Batteries are then tested, packaged, and shipped. 
     A number of trade-offs must be considered in optimizing lead-acid batteries for various standby power and transportation uses. High-power density requires that the initial resistance of the battery be minimal. High-power and energy densities also require the plates and separators be porous and, typically, that the paste density also be very low. High cycle life, in contrast, requires premium separators, high paste density, and the presence of binders, modest depth of discharge, good maintenance, and the presence of alloying elements and thick positive plates. Low-cost, in further contrast, requires both minimum fixed and variable costs, high-speed automated processing, and that no premium materials be used for the grid, paste, separator, or other cell and battery components. 
     A number of improvements have been made in the basic design of lead-acid electrochemical cells. Many of these have involved improvements in the characteristics of the substrate, the active material, as well as the bus bars or collector elements. For example, a variety of fibers or metals have been added to or embedded in the substrate material to help strengthen it. The active material has been strengthened with a variety of materials, including synthetic fibers and other additions. Particularly with respect to lead-acid batteries, these various approaches represent a trade-off between durability, capacity, and specific energy. The addition of various non-conductive strengthening elements helps strengthen the supporting grid but replaces conductive substrate and active material with non-conductive components. 
     In order to reduce the weight of the lead-acid electrochemical cells relative to their specific energy, various improvements have been disclosed. One approach has been to coat a light-weight, high-tensile strength fiber with sufficient lead to make a composite wire that could be used to support the grid of the electrode. Robertson, U.S. Pat. No. 275,859 discloses an apparatus for extrusion of lead onto a core material for use as a telegraph cable. Barnes, U.S. Pat. No. 3,808,040 discloses strengthening a conductive latticework to serve as a grid element by depositing strips of synthetic resin. Specifically, Barnes &#39;040 patent discloses a lead-coated glass fiber. These approaches, however, have been unable to produce a material with sufficient properties of high-corrosion resistance and high-tensile strength to be able to fabricate a commercially viable lead-acid battery that can survive chemical attack from the electrolyte. 
     Blayner, et al., have disclosed further improvements in the composition of the substrate to reduce the weight of the electrodes and to increase the proportion of conductive material. Blayner, U.S. Pat. Nos. 5,010,637 and 4,658,623. Blayner discloses a method and apparatus for coating a fiber with an extruded, corrosion-resistant metal. Blayner discloses a variety of core materials that can include high-tensile strength fibrous material, such as an optical glass fiber, or highly-conductive metal wire. Similarly, Blayner discloses that the extruded, corrosion-resistant metal can be any of a number of metals such as lead, zinc, or nickel. 
     Blayner discloses that a corrosion-resistant metal is extruded through die. The core material is drawn through the die as the metal is extruded onto the core material. Continuous lengths of metal wire or fiber are coated with a uniform layer of extruded, corrosion-resistant metal. The wire is then used to weave a screen that acts as a substrate for the active material. There are no fusion points at the intersections of the woven wires. The electrode may be constructed using such a screen as a grid with the active material being applied onto the grid. Rechargeable lead-acid electrochemical cells are constructed using pairs of electrodes. 
     Blayner discloses further improvements regarding the grain structure of the metal coating on the core material. In particular, Blayner discloses that the extruded corrosion-resistant metal has a longitudinally-oriented grain structure and uniform grain size. U.S. Pat. Nos. 5,925,470 and 6,027,822. 
     Fang, et al., disclose in their paper,  Effect of Gap Size on Coating Extrusion of Pb - GF Composite Wire by Theoretical Calculation and Experimental Investigation , J. Mater. Sci. Technol., Vol. 21, No. 5 (2005), optimizing the gap in extruding lead-coated glass fiber. Although Blayner does not disclose the relationship between gap size and extrusion of the lead coated composite wire, Fang characterizes gap size as a key parameter for the continuous coating extrusion process. Fang reports that a gap between 0.12 mm and 0.24 mm is necessary, with a gap of 0.18 mm being optimal. Fang further reports that continuous fiber composite wire can enhance load and improve energy utilization. 
     The present inventors have found that, despite improvements in lead-acid electrochemical cells for automotive applications, prior known lead-acid batteries have not been able to achieve the same performance as Li-ion or Ni-MH cells for similar applications. There remains a need, therefore, for further improvements in the design and composition of lead-acid electrochemical cells to meet the specialized needs of the automotive and standby power markets. Specifically, there remains a need for a reliable replacement for lithium-ion electrochemical cells in certain applications that do not entail the same safety concerns raised by Li-ion electrochemical cells. Similarly, there remains a need for a reliable replacement for Ni-MH and Li-ion electrochemical cells with the added benefits of low-cost and reliability of lead-acid electrochemical cells. In addition, there remains a need for substantial improvement in battery production capacity to meet the growing needs of the automotive and standby power segments. 
     The United States Department of Energy (USDOE) has issued Corporate Average Fuel Efficiency (CAFE) guidelines for automotive fleets. Previously, SUVs and light trucks were excluded from the CAFE averages for motor vehicles. More recently, however, integrated guidelines have emerged specifying fuel efficiency standards for passenger vehicles, light trucks, and SUVs. These guidelines require an average fuel efficiency of 31.4 miles per gallon by 2016. http://www.epa.gov/oms/climate/regulations/420r10009.pdf. 
     Anticipated improvements in internal combustion engine technology do not appear to be able to reach this goal. Similarly, the manufacturing capacity for pure hybrids and pure electric vehicles does not appear sufficient to be able to reach this goal. Thus, it is anticipated that some combination of micro-hybrids or mild hybrids, in which electrochemical cells provide some of the power for either stop/start or certain acceleration applications, will be necessary in order to meet the CAFE standards. 
     Lead-acid battery systems may provide a reliable replacement for Li-ion or Ni-MH batteries in these applications, without the substantial safety concerns associated with Li-ion electrochemistry and the increased cost associated with both Li-ion and Ni-MH batteries. 
     Further, the improved batteries of the present invention may be combined in hybrid systems with other types of electrochemical cells to provide electric power that is tailored to the unique automotive application. For example, a lead-acid battery of the present invention which features high-power can be combined with a Lithium-ion (“Li-ion”) or Nickel metal hydride (“Ni-MH”) electrochemical cell offering high energy, to provide a composite battery system tailored to the needs of the particular automotive standby or stationary power application, while reducing the relative sizes of each component. 
     SUMMARY 
     An aspect of the present disclosure includes an electrochemical cell having an electrode assembly, wherein the electrode assembly may include a plurality of electrode plates. Each electrode plate may include a current collector having a first portion and a second portion, and wherein each first and second portion may have a first surface and a second surface opposing the first surface. The first and second surfaces of the first portion may include a positively charged active material, and the first and second surfaces of the second portion may include a negatively charged active material. The plurality of electrode plates may include at least three electrode plates, such that the electrochemical cell may be arranged with a first portion of one plate of the at least three electrode plates electrochemically connected to a second portion of a second plate of the at least three electrode plates, and a first portion of the second plate of the at least three electrode plates electrochemically may be connected to a second portion of a third plate of the at least three electrode plates. 
     In various embodiments, the electrochemical cell may include the following features, either alone or in combination: each electrode plate may include a plurality of electrode connectors connecting the first portion to the second portion; each electrode plate may include shunt current mitigating means; the current collector may include a uniform current density; a first separator may be attached to the first surface of the first portion and a second separator may be attached to the first surface of the second portion; a plurality of electrode assemblies may be stacked in series for building voltage; an insulator may be connected to the top electrode plate, and the insulator may include at least one slit therein with an electrode plate extending there through; the electrochemical cell may be a lead-acid electrochemical cell; the electrode assembly may be connected to tabs; at least two electrode assemblies may be stacked in parallel for building capacity; there may be at least one power bus assembly including at least one bolt for building capacity; at least two of the electrode plates may be electrochemically connected at a ninety degree angle relative to one another; and the electrochemical cell may include a cross-sectional shaped selected from one of circular, rectangular, square, L-shaped, or U-shaped. 
     In some embodiments, an electrochemical storage device comprises a plurality of layer electrodes, wherein each layer electrode includes a first charged sector and a second charged sector, wherein the second charged sector is charged oppositely compared to the first charged sector, and wherein the plurality of layer electrodes are assembled with respect to each other such that the first charged sector of a first plate of the plurality of layer electrodes is laid below the second charged sector of a second plate of the plurality of layer electrodes located immediately above the first plate, wherein the charges of the first charged sectors of the first and second plates have a first sign and the charges of the second charged sectors of the first and second plates have a second sign that is opposite the first sign; a separator sector located, and enabling ionic charge exchange between the first charged sector of the first plate and the second charged sector of the second plate. 
     In some embodiments, the second charged sector of the first plate is laid below the first charged sector of the second plate, the electrochemical device further comprising an insulator sector located, and preventing ionic or conductive charge exchange, between the second charged sector of the first plate and the first charged sector of the second plate. In some embodiments, each of the plurality of the layer electrodes in circular. 
     In some embodiments, each sector has a semi-circle shape sized to about half of the corresponding layer electrode. In some embodiments, each plate of the plurality of layer electrodes further comprises a frame which houses the first charged sector and the second charged sector of the corresponding plate. In some embodiments, the electrochemical storage device further comprises a first cap and a second cap for encasing the plurality of layer electrodes. In some embodiments, the electrochemical storage device further comprises a conductive substrate for providing a conductive connection between the first charge sector and the second charged sector. 
     In some embodiments, each of the plurality of the layer electrodes has a rectangular shape. In some embodiments, each sector has a half-rectangle shape sized to about half of the corresponding layer electrode. 
     In some embodiments, an electrochemical storage device comprises a first electrochemical cell and a second electrochemical cell disposed in a common casing and each comprising an anode and a cathode, wherein the anode of the first electrochemical cell is disposed opposite the cathode of the second electrochemical cell; a separator disposed between the anode of the first electrochemical cell and the cathode of the second electrochemical cell, wherein the anode of the first electrochemical cell and the cathode of the second electrochemical cell are electrically insulated and in communication through an ionically conductive medium adsorbed in the separator; a common current collector disposed on the anode of the first electrochemical cell and the cathode of the second electrochemical cell, wherein the first and second electrochemical cells are electrically connected and insulated from ionic conduction and wherein the ionic separation of said first and second electrochemical cells mitigates shunt currents. 
     In some embodiments, the device further comprises said current collector providing substantially uniform current collection granting uniform current density. In some embodiments, the device further comprises a hydrophobic coating disposed on the portion of the common current collector between said anode and said cathode. In some embodiments, the device further comprises a physical barrier to ionically insulate said first and second electrochemical cells. In some embodiments, the device further comprises one positive and one negative terminal connection. In some embodiments, the device further comprises an insulation frame for disposing anodes and cathodes of two or more electrochemical cells in substantially the same plane. 
     Additional objects and advantages of the disclosure will be set forth in part in the description which follows, and in part will be apparent from the description, or may be learned by practice of the disclosure. The objects and advantages of the disclosure will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed. 
     The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one embodiments of the disclosure and together with the description, serve to explain the principles of the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic isometric view of a portion of a lead-acid electrochemical cell showing a plurality of electrode assemblies connected in a spiral configuration according to an embodiment of the present disclosure. 
         FIG. 2A  is a schematic isometric view of a portion of an electrode assembly according to an embodiment of the present disclosure. 
         FIG. 2B  is an exploded isometric view of a portion of the electrode assembly of  FIG. 2A . 
         FIGS. 3A and 3B  are side views of the electrode assembly of  FIG. 2A . 
         FIG. 4A  is a schematic top view of an electrode plate of the electrode assembly of  FIG. 2A . 
         FIG. 4B  is an exploded isometric view of the electrode plate of  FIG. 4A  with accompanying separator and pasting papers. 
         FIG. 5  is a schematic top view of an alternative embodiment of an electrode plate of the electrode assembly of  FIG. 2A  depicting the current collector. 
         FIG. 6  is an exploded isometric view of a lead-acid electrochemical cell module and package according to an embodiment of the present disclosure. 
         FIG. 7  is a schematic isometric view of a plurality of electrode assemblies connected in a spiral configuration according to another embodiment of the present disclosure. 
         FIG. 8  is an exploded isometric view of a portion of an electrode assembly of the lead-acid electrochemical cell of  FIG. 7 . 
         FIG. 9  is an exploded isometric view of a portion of a lead-acid electrochemical cell module according to another embodiment of the present disclosure. 
         FIG. 10  is a schematic isometric view of two stacked lead-acid electrochemical cell modules of  FIG. 9  connected in series. 
         FIG. 11  is a schematic isometric view of an electrode plate according to another embodiment of the present disclosure. 
         FIG. 12  is an exploded isometric view of a partial electrode assembly according to another embodiment of the present disclosure. 
         FIG. 13  is a schematic isometric view of a portion of a lead-acid electrochemical cell with a plurality of electrode assemblies in a stacked configuration according to another embodiment of the present disclosure. 
         FIG. 14  is a schematic isometric view of the lead-acid electrochemical cell of  FIG. 13  connected to a power bus. 
         FIG. 15  is an exploded isometric view of the power bus of  FIG. 14 . 
         FIG. 16  is an exploded isometric view of a partial lead-acid electrochemical cell module, power bus, and package according to another embodiment of the present disclosure. 
         FIG. 17  is a schematic isometric view of a lead-acid electrochemical cell with a plurality of electrode assemblies in a stacked configuration according to another embodiment of the present disclosure. 
         FIG. 18  shows a Ragone plot of various types of electrochemical cells. 
         FIGS. 19A-19F  shows a circular plate module in accordance with some embodiments of the present disclosure. 
         FIG. 20  shows an electrode assembly of a battery module according to some embodiments. 
         FIG. 21  shows two circular frames in accordance with some embodiments. 
         FIG. 22  shows the structure of a circular frame in accordance with some other embodiments. 
         FIG. 23  shows a circular module cover in accordance with one embodiment. 
         FIG. 24  shows the behavior of calculated capacity of circular plate modules as a function of the diameter of the circular plates, in accordance with some embodiments. 
         FIG. 25  shows a battery shaped as a rectangular box in accordance with some embodiments. 
         FIGS. 26A-26H  show a battery having a rectangular form factor in accordance with some embodiments. 
         FIGS. 27A and 27B  show a rectangular battery having a 192V voltage configuration according to one embodiment. 
         FIGS. 28A-28D  show a battery having a circular sector electrode design according to some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description refers to the accompanying drawings. Wherever possible, the same reference numbers may be used in the drawings and the following description to refer to the same or similar parts. Also, similarly-named elements may perform similar functions and may be similarly designed. Numerous details are set forth to provide an understanding of the embodiments described herein. In some cases, the embodiments may be practiced without these details. In other instances, well-known techniques and/or components may not be described in detail to avoid obscuring described embodiments. While several exemplary embodiments and features are described herein, modifications, adaptations, and other implementations are possible, without departing from the spirit and scope of the invention. Accordingly, the following detailed description does not limit the invention. Instead, the proper scope of the invention is defined by the appended claims. 
     Embodiments of the present disclosure generally relate to a design of a lead-acid electrochemical cell. Lead-acid electrochemical cells typically are in the form of stacked plates with separators between the plates. Accordingly, embodiments of the present disclosure relate to improved stacking of electrode plates in a variety of form factors. The improved stacking and variety of form factors of the lead-acid electrochemical cell design may enable lead-acid electrochemical cells to be used as part of lead-acid batteries, which, in turn, may be used in automobiles to aid in increasing fuel efficiency. 
     More specifically, embodiments of the present disclosure may include improvements to the design of a lead-acid electrochemical cell which may include improvements to the orientation of electrode plates as well as improvements for mitigating shunt currents. The improvements may result in a lead-acid electrochemical cell that may have a higher voltage while maintaining a lower weight and size. Alternatively, it also enables production of cells having higher capacity at the same relative voltage. 
     Embodiments of the present disclosure may allow for the use of lead-acid batteries in micro and mild-hybrid applications of vehicles, either alone or in combination with Ni-MH or Li-ion batteries. Some embodiments use other electrochemical batteries having a specific energy above 50 Wh/kg and a specific power above 500 W/kg. It should be emphasized, however, that embodiments of the present disclosure are not limited to transportation and automotive applications. Embodiments of the present disclosure may be of use in any area known to those skilled in the art where use of lead-acid batteries is desired, such as stationary power uses and energy storage systems for back-up power situations. Further, the present inventors intend that the elements or components of the various embodiments disclosed herein may be used together with other elements or components of other embodiments. 
       FIG. 1  depicts a lead-acid electrochemical cell  10  according to a first embodiment of the present disclosure. The lead-acid electrochemical cell  10  may include a plurality of electrode assemblies  12 . Each electrode assembly  12  may include a plurality of electrode plates positioned in electrochemical contact with each other. The electrode assemblies  12  may be connected in a spiral configuration to build voltage within the lead-acid electrochemical cell. In particular, the spiral configuration may enable a lead-acid electrochemical cell to build voltage while maintaining constant capacity. The number of electrode assemblies that make up the spiral configuration, as well as the configuration of each electrode assembly, may vary depending on the desired shape and desired voltage of the lead-acid electrochemical cell. 
     In addition, as shown in  FIG. 1 , the spiral configuration may have an opening  32  formed in the center of the stacked electrode assemblies, by virtue of the shapes of electrode assemblies  12 . The central opening  32  may extend through the entire spiral configuration, forming a central bore allows for the main positive and negative leads to run through each electrode assembly  12  and be connected to the top of the spiral configuration. 
     Each electrode assembly  12  in the lead-acid electrochemical cell may be separated by an insulator  14  ( FIG. 2B ). The insulator may be the cross-sectional shape of the electrode assembly and may include a radial slit  15 . For example, in the embodiment of  FIG. 1 , the cross-sectional shape of each electrode assembly  12  may be semi-circular. Accordingly, the insulator  14  may include a circular shape and a slit  15  along a radius. As shown in  FIG. 2B , the insulator  14  may further include a bottom surface and a top surface. Further, each electrode assembly  12  may include multiple electrode plates  24  with a top plate  24 D in contact with both the top and bottom surfaces of insulator  14 . For example, as shown in  FIG. 2B , the top plate  24 D of one electrode assembly may include a first portion in contact with the bottom surface of the insulator, and a second portion in contact with the top surface of the insulator. The spiral configuration of the lead-acid electrochemical cell may be achieved by connecting the second portion of the top electrode plate  24 D in one electrode assembly  12  to the first portion of a bottom electrode plate  24 A in another electrode assembly  12 . 
       FIG. 2A  and  FIG. 2B  of the present disclosure depict schematic views of an electrode assembly  12  of the lead-acid electrochemical cell of  FIG. 1 . As shown in  FIG. 2B , the electrode assembly may include four electrode plates  24 A-D. Each electrode plate may be in the shape of half of a semi-circular section, as shown in  FIG. 4A  and  FIG. 4B . 
     As shown in  FIG. 4A , each electrode plate  24  may include a first portion  28  and a second portion  30 . The first and second portions  28  and  30  may be connected by a plurality of electrode connectors  26 . Each portion may include a substrate, which may be a current collector (not shown). As described above, the electrode substrate may be of the type disclosed in U.S. application Ser. No. 13/350,505 for Improved Substrate for Electrode of Electrochemical Cell, filed concurrently herewith by Subhash Dhar, et al., the entire disclosure of which is incorporated herein by reference. 
     Thus, the substrate may include a grid-like structure formed of conductive material, with spaces there between for supporting active material. Accordingly, the substrate may include a sheet of material having aligned dimple-like spaces or a plurality of through-holes in linear patterns. Alternatively, the substrate may include a plurality of pieces of material, such as wires, woven together to form a mesh. In a further embodiment, the substrate may include an expanded sheet of material with holes there through. The substrate may include material that may result in an increased adhesion between the substrate and the active material, as well as increased surface conductivity and reduced corrosion of the electrode plate. 
     As shown in  FIGS. 4A and 4B , the positive and negative portions of each electrode plate are depicted as 90° sections. It will be apparent to persons of ordinary skill in the art that sections of various alternative geometries may be employed, without departing from the scope or spirit of the invention as claimed. For example, sections could be 30°, or 45°, 60°, or any other appropriate geometry. If 90° sections are employed, four pairs of positive and negative electrodes may comprise each layer; if 60° sections are employed, 6 pairs; if 45° sections are used, 8 pairs; if 30° sections are used, 12 pairs; and so forth. Persons of ordinary skill will appreciate that, as the number of sections per layer increases, the area of the active material in each section decreases, proportionately, at a constant radius. This decrease can be offset by increasing the radius of the electrode to provide more active material surface area as the number of sections increases. 
     The substrate may further be formed such that a relatively constant current density may be maintained throughout each electrode plate. For example, in the first embodiment of the electrode plate of  FIG. 4A , the electrode plate  24  may include a substantially semi-circular shape. Accordingly, the substrate of the electrode plate  24  may include a substantially semi-circular shape as well. Constant current density throughout the substrate may be achieved by spacing the current collector elements of the substrate closer together in the radial direction at the outer radius of the electrode plate than at the inner diameters, and farther apart at the inner radial extent of the plate, as shown in  FIG. 5 . 
     The active material may be placed onto each portion of the substrate such that a pseudo bi-polar electrode plate may be formed. The pseudo bi-polar design may be accomplished by disposing both positive and negative active materials in alternating fields on a common substrate. In one embodiment shown in  FIG. 4A , for example, the pseudo bi-polar design may include placing positive active material onto the first portion  28  of the substrate; and placing negative active material onto the second portion  30  of the substrate. This pseudo bi-polar design may offer lower resistance and higher power of the lead-acid electrochemical cell. Further, it may enable the lead-acid electrochemical cell to operate at a lower temperature, which may reduce the need for collateral cooling equipment. As shown in  FIG. 4A  and  FIG. 4B , the first portion  28  of each electrode plate  24  may be positive  16 , and the second portion  30  of each electrode plate  24  may be negative  20 , with the electrode connectors  26  between the negative and positive regions of the electrode plate. 
     Each positive portion  16  and negative portion  20  of each electrode plate may further include a top surface and a bottom surface. As shown in  FIG. 4B , a thin layer of pasting paper  22  may be disposed on the top and bottom surfaces of each portion of the electrode plate. Additionally, a separator  18  may be disposed adjacent the pasting paper on the bottom surface of each portion. 
     As previously disclosed, each electrode assembly  12  may include four electrode plates  24 A-D as shown in  FIGS. 2A and 2B . The electrode assembly  12  may be formed by stacking each plate  24  at a ninety degree angle relative to one another such that a positive portion  16  of one plate may be connected to a negative portion  20  of another plate. In one embodiment, for example, a first electrode plate  24 A having a positive portion  16  and a negative portion  20  may be the bottom plate of the electrode assembly. A second electrode plate  24 B having a positive portion  16  and a negative portion  20  may then be stacked onto the first electrode plate  24 A. This may be accomplished by turning the second electrode plate  24 B ninety degrees relative to the first electrode plate and placing the positive portion  16  of the second plate  24 B on top of the negative portion  20  of the first plate  24 A ( FIG. 2B ). A third electrode plate  24 C having a positive portion  16  and a negative portion  20  may be stacked upon the second plate  24 B in the same manner as previously discussed; and a fourth electrode plate  24 D may then be stacked upon the third electrode plate  24 C. The fourth electrode plate  24 D may be the top electrode plate of the electrode assembly  12  ( FIG. 2B ). 
     Upon placement of the fourth electrode plate  24 D, insulator  14  may be placed on the electrode assembly. As previously discussed, and shown in  FIG. 2B , the positive portion  16  of the fourth, i.e., top electrode plate  24 D may be connected to the negative portion  20  of the third electrode plate  24 C. The insulator  14 , including the slit  15 , may be placed on the electrode assembly such that the top of positive portion  16  of the fourth plate  24 D may be in contact with the bottom surface of the insulator  14 , and the bottom of the negative portion  20  of the fourth plate  24 D may be in contact with the top surface of the insulator  14 . Accordingly, the negative portion  20  of the fourth plate  24 D may be stacked with a free, positive portion  16  of a first plate  24 A of another electrode assembly  12 , which may thereby form the spiral configuration of the lead-acid electrochemical cell shown in  FIG. 1 . 
     Alternatively, the electrode assembly may be formed such that the free portion of the fourth plate  24 D is a positive portion and the free portion of the first plate  24 A is a negative portion. In addition, the free portion of the fourth plate  24 D of the top electrode assembly in the spiral configuration may be connected to a single portion plate in order to complete the circuit. In an alternative embodiment, the top plate  24 D of the top electrode assembly may only be a single portion plate, thereby completing the circuit with the connection to the third plate  24 D. 
     In some embodiments the electrode assembly is formed by solid-state plates, wherein the positive and the negative portion of the plates include thin-film active material produced through solid state deposition processes. Processes suitable to form active materials include but are not limited to physical vapor deposition, chemical vapor deposition, spray deposition, dip coating, spin coating, electroless deposition, electroplating and any combination of suitable processes to form thin-film coatings. Suitable forms of the film materials include materials formed in a high vacuum process, under an inert gas environment and in room atmosphere and pressures. 
     In some embodiments, the separator material is a thin film membrane that allows for ionic diffusion and transfer of hydrogen, oxygen and sulfate ions, e.g. H+, OH−, SO4− at rates that are comparable to liquid electrolyte diffusion. In some embodiments, the separator membrane is a polymeric membrane e.g. Nafion material. 
     In some embodiments the substrate material of the plates is a suitable thin film electrically conductive medium in a form of a foil or a solid film, In some embodiments, the thin film is a woven material selected from the group including metals, e.g. lead, conductive polymers, e.g. aniline based polymer, conductive ceramics, e.g. ebonex or conductive tin or titanium oxides. In various embodiments, the substrate material has a polished surface with a suitable attachment layer or a patterned surface to promote adhesion of the active material including holes, ridges, dimples interlocking features and stress mitigating features. 
     In various embodiments, the suitable electrolyte is fully solid or in the form of a gel or a liquid and dispersed with the positive and active materials in stoichiometric quantities or impregnated in the separator membrane or other parts of the electrode assembly acting as electrolyte reservoirs; 
     Alternatively, in some embodiments, the positive and negative electrode assembly constitutes a fuel cell relying on separation principles of a ionically conductive membrane. In some embodiments, a suitable fuel fluid is a gas, e.g. hydrogen or other suitable fuel. 
     The pseudo bi-polar design of each electrode plate may allow for the spiral configuration to build voltage in the lead-acid electrochemical cell to any desired value (e.g., 24V, 36V, 42V, or 48V) at a constant capacity, while maintaining a low weight of the lead-acid electrochemical cell. The low weight may be due to the sizes of the components of the electrode assembly, as well as the material-make up of each electrode plate. In addition, the stacking of the electrode plates at a ninety degree angle relative to one another may allow for thinner components. For example, in one embodiment, the electrode assembly  12  may include a diameter of about 8 inches and may be about 0.3 inches thick. More specifically, the positive portion  16  of the electrode may be about 0.082 inches thick; the negative portion  20  of the electrode may be about 0.06 inches thick; the separators  18  may be about 0.06 inches thick; and the pasting paper  22  may be about 0.004 inches thick. 
     Persons of ordinary skill in the art will understand that stacking of the electrode plates may be accomplished in any of a variety of ways. For example, the plates can be stacked so that the plates build, one upon the other, in a step-wise manner with each positive  16  and negative  20  portion and their accompanying connections  26 , lying in the same plane, as shown in  FIG. 2 . Alternatively, connectors  26  may be angled so that they are offset by the thickness of a plate, pasting papers and separator, to facilitate the rise in the plates as they are stacked. As a further alternative, the electrode plates can be formed having a helical geometric shape, to facilitate stacking the plates in a helical pattern, mitigating step discontinuities and reducing stresses on the connector  26 . 
     The lead-acid electrochemical cell may further include means for mitigating shunt currents due to leakage of electrolyte fluid from the electrodes and separators onto the electrode connectors, which may cause the electrodes to self-discharge. In one embodiment, the electrode connectors  26  and inner portion of a container proximate the electrode plates may be treated with a hydrophobic coating, which may prevent excess electrolyte fluid from wetting the electrodes, or electrode connectors  26 , or casing. In other alternative embodiments, the electrode connectors  26  may be blocked from leaking electrolyte fluid due to barriers formed on the edges of the positive and negative portions  16 ,  20  of each electrode plate. The barrier may be a coating or other material, including frame material or even excess active material that may frame each positive and negative portion and contain the electrolyte. Alternatively, in a further embodiment, the insulator may have a diameter that is larger than the diameter of both the electrode assembly the container in which the spiral configuration resides, such that the insulator may form a barrier with the container wall and soak up leaking electrolyte fluid. 
       FIG. 6  depicts a lead-acid electrochemical module  60  according to an embodiment. The module  60  may include a top portion  34 , a bottom portion  38 , and a casing  36 . Top and bottom portions  34 ,  38  may enclose the lead-acid electrochemical cell  10  within the casing  36 . Casing may include an inner opening  40 , which may be substantially the same diameter and height of the lead-acid electrochemical cell  10 , such that the lead-acid electrochemical cell may be fully disposed within the casing  36  and covered by the top and bottom portions  34 ,  38 . The module  60  may further include positive and negative terminals (not shown in  FIG. 5 ) attached to the lead-acid electrochemical cell, such that the module may be used to provide energy and power. 
     As previously disclosed, the spiral configuration may connect electrode assemblies  12  in order to build voltage while maintaining a constant capacity of the lead-acid electrochemical cell. In a second, alternative embodiment, the electrode assemblies  12  may be stacked such that the voltage of the lead-acid electrochemical cell remains constant while building capacity. Accordingly, in this second embodiment, instead of the top plate  24 D of one electrode assembly  12  being connected to the bottom plate  24   a  of another electrode assembly  12 , the top and bottom plates of a single electrode assembly may be connected to complete the circuit. Each electrode assembly  12  may be connected to a tab  50 , which may further be connected to a power bus assembly  500  for capacity building. 
       FIG. 15  illustrates the components of one embodiment of the power bus assembly  500 . Power bus assembly  500  may include a power bus  502 , a terminal  506 , a connector piece  504 , and a nut  508 . In addition, as shown in  FIG. 15 , a bolt  510  may be connected to the connector piece  504 , extend through the power bus  502 , and attach to the nut  508 . Bolt  510 , when connected to the connector portion  502  and nut  508 , may complete the connection of the bus system  500 , which may thereby building capacity. 
     As shown in  FIG. 15 , connector  504  may include a first through-hole  504   a  and a second through-hole  504   b  formed therein. First through-hole  504   a  may connect to the bolt  510 , and second through-hole  504   b  allow top portion of terminal  506   a  to extend there through. Terminal  506  may additionally include a bottom portion  506   b , that may sit atop a top surface of the lead-acid electrochemical cell  1000 . Top portion of terminal  506   b  may be an elongate member having a cross section that is substantially the same shape as the second opening  504   b . The bottom portion of terminal may be flat. Alternatively, as shown if  FIG. 14 , the bottom portion of terminal  506   b  may have a concave inner surface. 
     Power bus  502  may include an elongate member having a length that is substantially the same as the height of the lead-acid electrochemical cell. Power bus  502  may further have slits disposed along its length, the slits being configured to receive connections from electrode plates, where the connections are solidified by compressing the power bus  502  in compression. Further, as shown in  FIG. 15 , a top surface of the power bus  502  may be in contact with a bottom surface of the connector piece  504 , such that the connector piece  504  may carry current from the power bus  502  to the terminal  506 . Consequently, power bus  502  may be made of any material known to those skilled in the art that allows for the carrying of current and the building of capacity. 
     In a third embodiment of the present disclosure, the electrode plates may be rectangular in shape. The rectangular plates may be similar in area to the semi-circular electrode plates and may used to form similar-sized electrode assemblies and modules. For example,  FIG. 7  shows a lead-acid electrochemical cell  100  according to a third embodiment of the present disclosure. The embodiment of  FIG. 7  depicts stacking of rectangular electrode plates at a ninety degree angle relative to one another to form electrode assemblies, and connecting the electrode assemblies in the spiral configuration. As shown in  FIG. 7 , rectangular electrode plates may be connected to form electrode assemblies, and thereby a spiral configuration having a square cross-sectional shape. 
     Similar to the electrode assembly  12  of  FIG. 1 , the electrode assembly  112  of  FIG. 8  may include four rectangular electrode plates  124 A-D. Each electrode plate  124 A-D may include positive and negative portions connected by electrode connectors  126 . In addition, each electrode plate may include pasting paper and separators  118 . Further, as shown in  FIG. 8 , each electrode assembly  112  may be separated by an insulator  114 , which may include the same cross-sectional shape as that of the electrode assembly  112 , and while further may include a radial slit (not shown). 
       FIG. 9  depicts a lead-acid electrochemical cell module  200  according to a third embodiment of the present disclosure. Module  200  may include a casing  140 , a slotted tray  142 , and a drip tray  146 . Slotted tray  142  may include a plurality of slots  144 , which may allow excess electrolyte fluid to flow through the slotted tray  142  and into a collection portion on the drip tray  144 . The drip tray  146  may include outer edges  145 , which may be secured to inner edges of casing  140 , such that casing  140  and drip tray  146  may enclose the lead-acid electrochemical cell  100  sitting atop slotted tray  142 . Casing  140  and drip tray  146  may be secured via any means known to those skilled in the art. For example, in one embodiment, casing  140  and drip tray  146  may be held together via plastic ultrasonic welding. 
     The lead-acid electrochemical cell  100  may further include a tab  50  connected to a positive end and a tab  50  connected to a negative end of the spiral configuration. Tabs  50  may be securely connected to the positive and negative ends via any means known to those skilled in the art. For example, tabs  50  may be connected via soldering or ultrasonic welding. Tabs  50  may each contain a through-hole  52 , which may allow for passage of posts  148 . In addition, openings  141 ,  143 ,  147  in each of the casing  140 , slotted tray  142 , and drip tray  146 , respectively, may also allow for posts  148  to pass there through. 
     As shown in  FIG. 10 , posts  148  may extend out from respective openings  141  in the casing  140  so that they may act as positive and negative terminals for the lead-acid electrochemical cell module. Posts  148  may further include an end portion  150  with an opening therein. The opening in the end portion  150  may allow for individual lead-acid electrochemical cell modules  200  to be stacked upon one another ( FIG. 10 ). 
     A fourth embodiment may employ the square electrode assembly  112  geometry of the third embodiment to build capacity at a constant voltage, rather than building voltage as in the third embodiment. Similar to that disclosed in relation to the second embodiment, this fourth embodiment may include connecting the free portion of the top plate  124 D with the free portion of the first plate  124 A in order to complete the circuit and therefore form a 12V electrode assembly  112 . The electrode assemblies may  112  then be stacked and connected to the power bus assembly  500  in order to build capacity while maintaining a constant 12V of the lead-acid electrochemical cell. The fourth embodiment of the lead-acid electrochemical cell may further include a module that may be similar to that of the third embodiment. 
     The electrode plates may further be used form electrode assemblies, and thereby lead-acid electrochemical cell configurations, having a variety of cross-sectional shapes, in addition to circular and square. This variety of cross-sectional shapes may allow for stacked or spiral configurations of the lead-acid electrochemical cell to be placed in a variety of locations (e.g., in a vehicle) with little or no modification of the design of the location (e.g., vehicle frame) to accommodate the lead-acid electrochemical cell system. In these further embodiments, for example, each electrode assembly may include more than four plates. In addition, formation of these electrode assemblies may include stacking of the electrode plates linearly relative to one another, as well as at a ninety degree angle relative to one another. For example, in one embodiment, rectangular plates may be used to form a spiral configuration with a rectangular cross-section. Accordingly, there may be more electrode plates along the length of each electrode assembly than along the width. 
     In one embodiment, electrode plates may be oriented such that resulting electrochemical cells may provide volumetric efficiency in three orthogonal directions. For instance, the orientation of the electrochemical cells may provide improved dimensions in an x-direction, a y-direction, and/or a z-direction, where the xyz axes are not oriented in any particular way relative to an electrochemical cell casing. Alternatively, the orientation of the electrochemical cells may provide improved dimensions in an x-direction, a y-direction, and/or a z-direction, where the xyz axes are oriented relative to an electrochemical cell casing. As described above and below, the electrochemical cells may be united through ionic connections and a common current collector in such as way as to build voltage or capacity in the direction of one of the orthogonal directions x, y, z. 
     A fifth embodiment of the present disclosure may include formation of electrode plates into an electrode assembly, where the electrode assembly may include an L-shaped cross-section. Each electrode assembly may include electrode plates with positive and negative portions connected by electrode connectors. In addition, each electrode plate may include pasting paper and separators. Further, each electrode assembly may be separated by an L-shaped insulator having at least one slit to enable spiral connection of the L-shaped electrode assemblies. In addition, each electrode plate may further include means for mitigating shunt currents (e.g., hydrophobic coating on electrode connectors, hydrophobic framing of the plates, or an oversized insulator for soaking up electrolyte fluid). 
     The L-shaped lead-acid electrochemical cell may further include an L-shaped module. Similar to the circular and square modules, the L-shaped module may include a casing, slotted tray, and drip tray for collecting leaking electrolyte fluid. There may further be a tab connected to positive and negative ends of the L-shaped spiral configuration, such that the tabs may be connected to shafts that form terminals of the L-shaped lead-acid electrochemical cell. 
     An alternative, sixth embodiment of the L-shaped electrode assemblies may further include a capacity building geometry, similar to the other capacity-building embodiments disclosed herein. The L-shaped electrode assemblies in the sixth embodiment may each be connected in parallel, with each assembly terminating in a tab, with each of the respective tabs connected to the power bus assembly  500 . The capacity-building L-shaped electrochemical cell may be housed within a module that is similar to the L-shaped module for the spiral configuration. 
     A seventh embodiment of the present disclosure may an electrode assembly having a U-shaped cross-sectional shape. The seventh embodiment may build voltage at a constant capacity, as disclosed herein. Alternatively, an eighth embodiment may include a U-shaped electrode assembly disposed to build capacity.  FIG. 17  illustrates a lead-acid electrochemical cell  2000  according to an eighth embodiment of the present disclosure. The lead-acid electrochemical cell  2000  may include a plurality of electrode assemblies  2012  stacked, such that voltage may remain constant while capacity may be built. Each electrode assembly  2012  includes the U-shaped configuration, such that the lead-acid electrochemical cell  2000  may fit within a module that may include an intermediate separator  2104 . The lead-acid electrochemical cell  2000  may further include a power bus  500  on each end to build capacity. 
     As a further alternative, the electrochemical cell may be configured in an elongated rectangular shape.  FIG. 11  illustrates an electrode plate  1024  of a lead-acid electrochemical cell according to a ninth embodiment of the present disclosure. Similar to the electrode plates  24 ,  124  in  FIG. 4A  and  FIG. 8 , the electrode plate  1024  may include a first, positive portion  1028  and a second, negative portion  1030 , with electrode connectors  1026  there between. 
     In the ninth embodiment, as shown in  FIG. 12 , the electrode assembly may be disposed in parallel in a capacity-building configuration. As shown in  FIG. 12 , electrode assemblies may be formed by aligning a desired number of electrode plates  1024 , which may form the bottom portion of the electrode assembly. The top portion of the electrode assembly may be formed by aligning a positive portion  1028  of a top plate with a negative portion  1030  of a bottom plate, and so on. Separators may be located between each of the stacked positive and negative portions. In addition, formation of the electrode assembly may result in a free positive portion  1028  of a bottom electrode plate  1024  at one end, and a free negative portion  1030  of a bottom electrode plate  1024  at the opposite end. Individual negative and positive portions, respectively may be placed on these free ends in order to complete the circuit. Electrode assemblies may be formed of any desired voltage. For example, the electrode assembly  1010  of  FIG. 12  may be 12 volt assembly. 
       FIG. 13  illustrates a lead-acid electrochemical cell  1000 , which may include the stacked electrode assemblies  1024  of  FIG. 13 . The lead-acid electrochemical cell  1000  may include tabs  50 . Similar to the tabs  50  in the lead-acid electrochemical cell  100  of  FIG. 7 , each tab may include a through-hole  52  and may be connected via soldering or ultrasonic welding to a positive end and a negative end of each electrode assembly.  FIG. 13 , however, illustrates that tab  50  may be connected to two electrode assemblies, as opposed to only one. 
       FIG. 14  further illustrates that each end of the lead-acid electrochemical cell  1000  may be connected to a power bus assembly  500 , which may allow for the individual electrode assemblies  1024  to be connected in parallel in order to build capacity of the lead-acid electrochemical cell  1000 . 
       FIG. 16  illustrates a lead-acid electrochemical cell module  1200  including the lead-acid electrochemical cell  1000  of  FIG. 14 . Similar to the lead-acid electrochemical cell module  200  of  FIG. 9 , the lead-acid electrochemical cell module  1200  may include a casing  1202 , a slotted tray  1204  with a plurality of slots  1205 , and a drip tray  1206  for collecting electrolyte fluid that seeps through the slots  1205  of the slotted tray. The casing  1202 , slotted tray  1204 , and drip tray  1206  may include a length, width, and height that are slightly larger than the dimensions of the lead-acid electrochemical cell  1000 , such that the casing  1202  and drip tray  1206  may completely enclose the lead-acid electrochemical cell  1000 . Further, similar to the module  200  of  FIG. 10 , the casing  1202  and the drip tray  1206  may be held together via any process known to those skilled in the art, including, but not limited to plastic ultrasonic welding. 
     Various embodiments use novel shapes for the electrode plates and accordingly increase the charge capacity or efficiency of the battery.  FIG. 19A  shows a circular plate module  1900  in accordance with some embodiments of the present disclosure. Circular plate module  1900  includes two caps  1910  at the top and bottom; a plurality of circular plates  1920  between the two caps; and a plurality of nuts and bolts assemblies  1930  (labeled as two end-nuts-and-bolts assemblies  1930   a  and four side-nuts-and-bolts assemblies  1930   b ). Top and bottom caps  1910  are tightened by the plurality of nuts and bolts assemblies  1930  on the two sides of the plurality of circular plates  1920 , and hold those plates together. Moreover, top and bottom caps  1910  each includes a terminal  1912  (visible in  FIG. 19A  for top cap only) through which the module connects to a terminal of the battery or another module. 
       FIG. 19B  shows a disassembled view of circular plate module  1900  and its various parts in accordance with some embodiments. In particular, in  FIG. 19B , module  1900  includes one layer positive terminal  1920 P, one layer negative terminal  1920 N, five layer electrodes  1920 E, six bolts  1930 B, six nuts  1930 N (of which four are visible), and four bushings  1932  (of which three are visible). 
     In the embodiments of  FIGS. 19A and 19B , the disassembled parts shown in  FIG. 19B  combine into assembled module  1900  of  FIG. 19A . In particular, when assembling the parts shown in  FIG. 19B  into assembled module  1900  of  FIG. 19A , the bolts  1930 B pass through designated holes in layer positive terminal  1920 P, either designated holes in layer electrodes  1920 E or bushings  1932 , and designated holes in layer negative terminal  1920 N, and then engage nuts  1930 N. More specifically, two of the bolts, marked by arrows, correspond to end-nuts-and-bolts assemblies  1930   a  in  FIG. 19A , and pass through the holes in layer electrodes  1920 E. The other four bolts correspond to side-nuts-and-bolts assemblies  1930   b  in  FIG. 19A  and pass through bushings  1932 . 
     When assembling the module shown in  FIG. 19B , layer electrodes  1920 E and layer negative or positive terminals are positioned on top of each other with a half turn for each layer compared to the previous, such that the positive half layers of one plate is positioned right below the negative half layer of the next plate, or vice versa. 
     Various embodiments use different combinations of layer electrodes and layer negative or positive terminals to result in various battery powers for the module. For example, in some embodiments such as the one shown in  FIG. 19B , module  1900  includes five layer electrodes  1920 E placed between one layer positive terminal  1920 P and one layer negative terminal  1920 N. In some embodiments, such a combination of electrodes provides a twelve volt battery module. 
       FIG. 19C  shows a detailed structure of layer electrode  1920 E according to some embodiments. In  FIG. 19C , layer electrode  1920 E includes negative half layer  1924 , positive half layer  1926 , wire substrate  1920 W, two thin separator half layers  1927   t - 1  and  1927   t - 2 , thick separator half layer  1927 T, circular frame  1920 F, frame o-ring  1921 , and insulator half layer  1925 . 
     These parts are assembled in the order and orientations shown in  FIG. 19C  to generate one layer electrode  1920 E shown in  FIG. 19B , in accordance to some embodiments. In particular wire substrate  1920 W is strung over circular frame  1920 F to create a wire mesh. This mesh is then embedded in the active materials included in negative and positive half layers  1924  and  1926  to form an active material layer. An o-ring  1921  is included for sealing the gap between two subsequent electrode layers. Negative half layer  1924  is then covered underneath by, in order, thin separator half layer  1927   t - 1 , insulator half layer  1925 , and thin separator half layer  1927   t - 2 . Positive half layer  1926 , on the other hand, is covered underneath with a thick separator half layer  1927 T. 
     In various embodiments, layer electrodes  1920 E are assembled such that negative and positive half layers of abutting layer electrodes come in contact. In particular, when a second layer electrode  1920 E is positioned over a first layer electrode to form a module  1900 , such as that seen in  FIG. 19B , the second one is rotated with respect to the first one by 180 degrees around its central axis. In this manner, the negative half layer of the second layer electrode is positioned on top of the positive half layer of the first layer electrode and the positive half layer of the second layer electrode is positioned on top of the negative half layer of the first layer electrode, in each case with some separators or insulators coming between them. For example, in one set-up, the exploded view shown  FIG. 19C  represents the first layer electrode sandwiched between a second layer electrode on top and a third layer electrode at the bottom. The second and third layer electrodes, not shown, will be oriented similar to each other, but rotated by 180 degrees with respect to the first layer electrode. In this exemplary set-up, negative half layer  1924  of the first layer is sandwiched between the positive half layers of the second and third layer electrodes, with a thick separator half layer coming before the positive half layer above it, and thin separator  1927   t - 1 , insulator  1925 , and thin separator  1927   t - 2  respectively coming before the positive half layer below it. In a similar manner, positive half layer  1926  of the first layer electrode is sandwiched between negative half layers of the second and third layer electrodes, with a thin separator half layer, an insulator half layer, and another thin separator half layer coming before the negative half layer above it, and the thick separator  1927 T coming before the negative half layer below it. 
     In various embodiments, the insulator half layer is an insulating layer that prevents the active half layers on its two sides from exchanging charges. In the above described exemplary set-up, for instance, the insulator half layer of the second layer electrode prevents positive half layer  1926  of the first layer electrode from exchanging charges with the negative half layer of the second layer electrode located above it. Similarly, insulator half layer  1925  prevents negative half layer  1924  from exchanging charges with the positive half layer of the third layer electrode located below it. 
     In various embodiments, the separator half layer is an ionically conductive layer that is in contact with one or two active half layers. In some embodiments, the separator half layer preserves some of the electrolyte in the active half layer to which it contacts. Further, in various embodiments, the separator half layer is in contact with two active half layers on its two sides, enables ionic charge exchanges between those half layers, thus forming a unit cell. In the above described exemplary set-up, for instance, thin separator half layer  1927   t - 1  is in contact with negative active material  1924  above it and preserves and exchanges ions with that negative half layer. Similarly, thin separator half layer  1927   t - 2  is in contact with a positive active material located below it. Thick separator half layer  1927 T, on the other hand, enables ionic charge exchanges between positive half layer  1926  of the first layer electrode and the negative half layer of the third layer electrode below. Similarly, the thick separator half layer of the second layer electrode enables ionic charge exchanges between negative half layer  1924  and the positive half layer electrode of the second layer electrode. This combination of positive half layer, separator half layer, and negative half layer creates a unit cell inside module  1900 . Thus in  FIG. 19C , for example, negative half layer  1924  forms a unit cell with the positive half layer above it, while being insulated from the positive half layer below it. Similarly, positive half layer  1926  forms a second unit cell with the negative half layer below it, while being insulated from the negative half layer above it. These unit cells of the module are connected to each other in series via wire substrate  1920 W. 
     In various embodiments, the wire substrate is a mesh created by a single-direction conductive wire, which enables conductive electron exchanges between the two active half layers that it connects. The wire substrate thus connects within the same layer electrode the positive half layer of one unit cell to the negative half layer of another unit cell. In the above-described exemplary set-up, for instance, in the first layer electrode shown in  FIG. 19C , wire substrate  1920 W connects negative half layer  1024 , belonging to the first unit cell, to positive half layer  1926 , belonging to the second unit cell. 
     In various embodiments, circular plate module  1900  includes a set of unit cells connected in series. In some embodiments, each unit cell the middle is formed between two abutting layer electrodes, in the manner detailed above. Further, two end unit cells are formed between a layer electrode and an abutting layer positive terminal or layer negative terminal For example, in the embodiment shown in  FIG. 19B , the first layer electrode terminal  1920 E- 1  includes a negative half layer  1924 - 1 , which forms a unit cell with positive half layer  1926 -P in layer positive terminal  1920 P. The fifth layer electrode  1920 E- 5 , on the other hand, includes a positive half layer  1926 - 5 , which forms a unit cell with negative half layer  1924 -N in layer negative terminal  1920 N. 
       FIGS. 19D and 19E  show the structure of the layer positive terminal and the layer negative terminal in more detail and in accordance with some embodiments.  FIG. 19D  shows that layer positive terminal  1920 P includes, in consecutive layers starting from top, cap  1910 ; thin separator half layer  1027   t - 1  along with a lead sheet half layer  1954 ; positive half layer  1926 ; wire substrate  1920 W; thick separator half layer  1927 T along with a gasket half layer  1952 ; and insulator  1925  and thin separator half layer  1027   t - 2 . Layer positive terminal  1920 P also includes circular frame  1920 F, frame o-ring  1921 , a terminal  1956  and a terminal o-ring  1957 . 
       FIG. 19E  shows that layer negative terminal  1920 N includes, in various layers starting from bottom, cap  1910 ; PVC half layer  1958  along with holed gasket half layer  1952   h ; another PVC half layer  1958  along with holed PVC half layer  1958   h ; insulator  1925  along with another holed PVC half layer  1958   h ; thin separator half layer  1927   t  along with lead sheet half layer  1954 ; wire substrate  1920 W; and negative half layer  1924  along with gasket half layer  1952 . Layer negative terminal  1920 N also includes circular frame  1920 F, frame o-ring  1921 , a long terminal  1956 L and terminal o-ring  1957 . 
     In some embodiments PVC is used to manufacture circular frame  1920 F, insulator half layer  1925 , cap  1910 , and PVC half layers  1958  and  1958   h . Moreover, lead is used to manufacture wire substrate  1020 W, terminals  1956  and  1956 L. Further, EPDM rubber of 70 A durometer is used in manufacturing o-rings  1921  and  1957 , and gasket half layers  1952  and  1952   h.    
     Parts  1924  and  1926  are respectively the negative and positive active materials. Thin and thick separators  1927   t  and  1927 T are made of fiberglass mats of different thicknesses. In particular, in the embodiment shown in  FIGS. 19C-19E , thick separator half layer  1927 T is thicker than thin separator half layer  1927   t . Moreover, positive active material  1926  is thicker than negative active material  1924 . In these embodiments, thin separator half layer  1927   t  is included on the side that also includes negative half layer  1924  to compensate for the smaller thickness of negative half layer  1924  compared to positive half layer  1926 . Moreover, as explained, separator half layers  1927  preserve the electrolyte of the active layer with which they contact. 
     In various embodiments, the layer electrodes are assembled into a circular plate module in a manner that provide a continuous charge path among the plates.  FIG. 19F  shows the charge path of an assembly of layer electrodes, including layer electrodes  1920 E- 1  to  1920 E- 4 , in a circular module  1900  in accordance with some embodiments. In  FIG. 19F , vertical and horizontal arrows indicate direction of charge transfer. Specifically, horizontal arrows  1942  indicate a conductive electron transfer from one unit cell to the next unit cell in the assembly, through a wire substrate. Vertical arrows  1944 , on the other hand, indicate ionic charge transfer within a unit cell. an ionic charge transfer through a separator from the left hand side (positive) half layer of layer electrode  1920 E- 2  to the left hand side (negative) half layer of layer electrode  1920 E- 3 . In some embodiments, the voltage produced by a unit cell is around two volts. In the embodiment shown in  FIG. 19B , for example, module  1900  assembles six unit cells and the total voltage generated by module  1900  is around twelve volts. 
     In various embodiments, layer electrodes  1920 E or layers for positive and negative terminals are manufactured by assembling its various parts in some specific order. In the embodiment shown in  FIG. 19C , for example, when manufacturing layer electrode  1920 E, wire substrate  1920 W can be strung into the grooves etched on the upper face of circular frame  1920 F to create a wired-frame assembly. This wired-frame assembly can then be covered on the one side with negative active material to form negative half layer  1924  and on the other side with positive active material to form positive half layer  1926 . Insulator and separator half layers  1925  and  1927  can then be attached on the appropriate faces of the negative and positive half layers 
     Different embodiments use different structures for the wired-frame assembly or for combining the wired-frame assembly with the remaining parts of a an layer electrode.  FIG. 21  shows two circular frames  2120 E- 1  and  2120 E- 2  in accordance with two different embodiments. Circular frame  2120 E- 1  has wire grooves  2152  etched on a section of its perimeter in a manner that a wire substrate strung into the grooves does not leave the perimeter of the frame and does not touch the perimeter of the wired-frame assembly. Circular frame  2120 E- 2 , on the other hand, has wire grooves  2154  etched along the length of its perimeter in a manner that a wire substrate strung into the grooves forms part of the perimeter of the wired-frame assembly. In some embodiments using circular frame  2120 E- 2 , frame o-ring  1921  is used to seal the perimeter of the wired-frame assembly and prevent electrolyte from leaking out. 
       FIG. 22  shows the structure of a circular frame  2220 F in accordance with some other embodiments. Circular frame  2220 F includes a perimeter section  2220 Fp, a central diameter section  2220 Fd, and an O-ring sealing  2258 . Perimeter section  2220 Fp has grooves formed on it for the wire substrate in the form of vertical channels  2254 . Diameter section  2220 Fd, on the other hand, has grooves formed on it for the wire substrate in the form of horizontal channels  2256 . 
     O-ring sealing  2258  provides a sealing mechanism to prevent leakage of the byproducts, such as acids, or gases generated by the battery. Moreover, in some embodiments, such leakage is also prevented in the center by cutting out along diameter section  2220 Fd, a channel such as potting compound area  2257 . After lead-wire substrate is strung on circular frame  2220 F, an epoxy is poured into area  2257  to seal in the wire. In some embodiments, the epoxy can be wax or other suitable hydrophobic materials. The epoxy is used to prevent or reduce the leakage of the battery between half layers. 
     Various embodiments change the shape or geometry of the module covers to improve the characteristics of the battery.  FIG. 23  shows a circular module cap  2300  in accordance with one embodiment. Module cap  2300  includes six sectors  2302  and a terminal location  2304 . Each of sectors  2302  includes a middle section, which has a reduced thickness and is a surrounded by a thicker rim. Because of the reduced thickness in the middle of sectors  2302 , module cap  2300  is lighter than a cap that has a uniform thickness and is otherwise similar to module cap  2300 . For example, in some embodiments each circular module cap  2300  for the top or bottom covers measures eight inches in the outside diameter, seven inches in the inside diameter, and ¼ inches in thickness. In various embodiments, top and bottom covers are injection molded using PVC. In these embodiments, module cap  2300  weighs around 140 grams, while a similarly dimensioned cap with a uniform thickness weights around 270 grams. Lighter covers reduces the weight of the battery, and thus increases its specific energy or specific power. 
       FIG. 20  shows an electrode assembly  400  of a battery module according to some embodiments. Assembly  400  includes semi-circular shaped full electrode plates  402 , quarter-circular shaped positive and negative end plates  404  and  406 , isolator layer  408 , separator plates  410 , positive terminal  412  and negative terminal  414 . Each full electrode plate  402  includes a positive half plate  402 P and a negative half plate  402 N. Full electrode plates  402  are assembled in a manner that when a full plate is positioned above another full plate, it is rotated by 90 degrees about the axis of electrode assembly  400 , such that positive half plate  402 P of one plate is positioned against negative half plate  402 N of the other plate. Moreover, a separator  410  is inserted between these two oppositely charge half plates to provide ionic connection between them. This combination of negative half plate of one plate ionically connected to a positive half plate of another plate located over or under the first plate creates a unit cell. Moreover, the wire connection between the positive half plate  402 P and negative half plate  402 N in the same full plate  402  provides a series connects between two consecutive unit cells. Positive end plate  404  forms a unit cell with the negative half plate  402 N positioned against it (under it in  FIG. 20 ). Similarly, negative end plate  406  forms another unit cell with the positive half plate  402 P positioned against it (above it in  FIG. 20 ). 
       FIG. 24  shows the behavior of calculated capacity of circular plate modules as a function of the diameter of the circular plates, in accordance with some embodiments.  FIG. 24  depicts graph  2400  in which abscissa  2410  lists the electrode diameter in inches and ordinate  2420  lists the corresponding calculated capacity in Ampere Hours (ah). The curve  2430  shows the calculated values for the capacity as a function of the diameter. In particular, curve  2430  shows that increasing the diameter of the plates causes the calculated capacity to increase in a non-linear manner. Moreover, curve  2430  shows that, in one embodiment, the electrode diameter is set to seven inches and the capacity of the module is around 6.5 ah. 
     In some embodiments, a battery module is made of plates that have non-circular shapes.  FIG. 25  shows a battery  2500  shaped as a rectangular box (rectangular prism) in accordance with some embodiments. Battery  2500  includes one or more rectangular plates  2510 . In some embodiments, rectangular plate  2510  includes a rectangular active module  2520  and a rectangular nest module  2530 . 
     Rectangular active module  2520  fits inside rectangular nest module  2530 . Rectangular active module  2520  includes a rectangular frame  2520 F that houses a rectangular negative half layer  2524  and a rectangular positive half layer  2526 . Rectangular nest module  2530 , on the other hand, contains a rectangular isolator  2525  and a rectangular separator  2527 . 
     In various embodiments, two different frames thus comprise one layer of the battery module, in a manner similar to that shown in  FIG. 25 . A first frame contains two active half layers including two different types of active materials. The second frame has the same shape as the first frame and includes a separator or an isolator, or both. In various embodiments, these two types of frames are manufactured separately and are then put together to create one layer of a battery module. Multiple layers are then assembled to create the battery module. In some embodiments, when assembling the layers, each layer is rotated with respect to the layer below or above it, such that the negative and positive half layers of neighboring layers face each other. 
     In some embodiments, a number of rectangular layers are assembled to form a rectangular module with a desired output voltage.  FIGS. 26A and 26B  show a 12 volt rectangular module  2600  in assembled and disassembled forms according to some embodiments. As shown in  FIG. 26B , rectangular module  2600  includes a top layer  2610 , five current repeating frames  2630 , and a bottom layer  2650 . Top layer  2610  includes a top cover  2610 C and an upper half-electrode frame  2620 . Bottom layer  2650  includes a bottom cover  2650 C and a lower half-electrode frame  2640 . In the embodiment shown in  FIGS. 26A and 26B , upper half electrode frame  2620  includes a negative half layer and lower half electrode frame  2640  includes a positive half layer, similar to positive and negative half layers discussed above. In various embodiments, module  2600  can be oriented and used differently such that, for example, the negative and positive half layers are respectively positioned at the bottom and at the top, or in any other orientation. 
       FIGS. 26C and 26D  respectively show assembled and disassembled views of center repeating frame  2630  of module  2600  according to some embodiments. As shown in  FIGS. 26C and 26D , current repeating frame  2630  includes a gasket, a negative acid reservoir half rectangle, positive and negative active material half rectangles, a wire substrate, a potting compound, an inner frame, a separator half rectangle, a positive acid reservoir half rectangle, and an outer frame that includes an isolator half rectangle. These parts generally function in a manner similar to the parts of layer electrodes discussed above. In particular, in some embodiments, negative and positive acid reservoir half rectangles are made of thin separator material. In the embodiment shown in  FIG. 26D , negative and positive acid reservoirs respectively cover negative and positive active material half rectangles from above or below, and each function as a reservoir of acid for the corresponding active material half rectangle. In some embodiments the gasket is made of EPDM rubber, other embodiments include Viton or similar elastomers, and acts as a washer between a center repeating frame and the one above it. The inner frame is made of a suitable acid resistant plastic and functions as a general frame for the active material, the wire substrate, the acid reservoirs, and other parts. The potting compound is a curable epoxy compound and functions as a barrier for acid migration between positive and negative active material 
       FIGS. 26E and 26F  respectively show assembled and disassembled views of top layer  2610  of module  2600  according to some embodiments. Top layer  2610  includes top cover  2610 C and upper half-electrode frame  2620 .  FIG. 26F  also shows, in accordance with some embodiments, different parts of upper half-electrode frame  2620  which include a gasket, a negative terminal, a current collector, a negative acid reservoir half rectangle, a potting compound, a wire substrate, an active material half rectangle that is negative, a separator half rectangle, a spacer half rectangle, and an outer frame that includes a separator half rectangle. The current collector is made of a lead metal sheet and collects current from the active material and delivers it to the negative terminal. The spacer half rectangle is made of EPDM rubber or similar acid resistant elastomer and compensates for thickness difference between the substrate and isolator components. 
       FIGS. 26G and 26H  respectively show assembled and disassembled views of bottom layer  2650  of module  2600  according to some embodiments. Bottom layer  2650  includes bottom cover  2650 C and lower half-electrode frame  2640 .  FIG. 26H  also shows, in accordance with some embodiments, different parts of lower half-electrode frame  2640  which include a gasket, an active material half rectangle that is positive, a spacer, a wire substrate, a potting compound, an inner frame, an acid reservoir for positive plate, an outer frame that includes an isolator half rectangle, a current collector, a positive terminal, and a second gasket. 
     Various embodiments combine a larger number of rectangular frames to create rectangular modules with a larger output.  FIGS. 27A and 27B  show a 192 volt rectangular module  2700  according to one embodiment. Rectangular module  2700  includes a lid  2710 , positive bus  2722  and negative bus  2724 , two electrode stacks  2730 , center bus  2740 , and case  2750 . In this embodiment the center bus connects the lower terminal of stacks  2730  together in a series electrical connection. 
     Some embodiments use a spiral configuration of unit cells. In some embodiments, the spiral configuration provides a multi-helix current path through the electrode stack.  FIGS. 28A-D  show a circular spiral module  2800  according to some embodiments. Circular spiral module  2800  includes a plurality of partial modules  2810  assembled in a spiraling manner, as described below in more detail. 
       FIGS. 28B and 28C  show details of partial module  2810  according to some embodiments. Partial module  2810  is shaped as a sector of a circle. In the embodiment shown in  FIGS. 28A-D , partial module  2810  is shaped as a 60 degree angle sector including two 30 degree half sectors with positive and negative active materials. 
       FIGS. 28B and 28C  show various parts of partial module  2810 . Partial module  2810  includes frame  2812 , positive and negative active material half sectors  2814  and  2815 , wire substrate  2816 , isolator half sector  2817 , and separator half sector  2818 . The negative and positive active materials, the isolator, and the separator function in a manner similar to that explained above in circular plate module  1900  or other similar modules. 
       FIGS. 28A and 28D  show the stacking of multiple partial modules  2810  to form circular spiral module  2800 , according to some embodiments. In particular, as shown in  FIG. 28D , circular spiral module  2800  includes five partial modules  2810 - 1  to  2810 - 5 . The partial modules are stacked in a spiral manner so that the negative half sector of a partial module is located underneath and connected ionically to the positive half sector of the partial module above it. For example, the negative half sector of partial module  2810 - 1  is located underneath and connected ionically via a separator to the positive half sector of partial module  2810 - 2 . Similarly, the negative half sector of partial module  2810 - 2  is located underneath and connected ionically via a separator to the positive half sector of partial module  2810 - 3 , and so on. 
     In this manner, a set of partial modules  2810  form a group of unit cells connected in series. In particular, each unit cell includes the negative half sector of partial module  2810 - i , the positive half sector of the partial module  2810 - i+ 1 located above the negative half sector, and the separator between these two half sectors. Each unit cell, thus formed, is connected in series with the cells before or after it by the trans-electrode substrates  2816 . For example, one unit cell forms between the negative half sector of partial module  2810 - 1  and the positive half sector of partial module  2810 - 2  located above it. This unit cell is connected serially to the unit cell before and after it respectively by the trans-electrode substrate  2816  in partial modules  2810 - 1  and  2810 - 2 . 
     In  FIG. 28D , the arrows show the direction of the electrons transferred inside and among these serially connected unit cells. In particular, each horizontal arrow shows the conductive transfer of charge from one unit cell to the next one, that is, from the positive half sector of each partial module  2810 - i  to the negative half sector of the same partial module through the trans-electrode substrate of that partial module. Each vertical arrow, on the other hand, shows the ionic transfer of current within each unit cell, that is, from the negative half sector of a partial module  2810 - i  to the positive half sector of the next partial module  2810 - i+ 1 positioned above the negative half sector through the separator inserted between them. Thus, partial modules  2810 - 1  to  2810 - 5  form a serially connected set of four unit cells and two half sectors at the start and the end. Some embodiments include a gasket which prevents internal shorting or electrolyte loss. In some embodiments a gasket prevents electrolyte loss in a manner similar to that explained above in circular plate module  1900  or other similar modules. In  FIG. 28C , for example, internal shorting is mitigated by the current isolator  2817 . 
     In some embodiments, the above-discussed design is used in solid-state batteries, lead acid batteries, fuel cell batteries, or some other types of electrochemical batteries. Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. For example, various elements or components of the disclosed embodiments may be combined with other elements or components of other embodiments, as appropriate for the desired application. Thus, it is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.