Divided energy electrochemical cell systems and methods of producing the same

Embodiments described herein relate to divided energy electrochemical cells and electrochemical cell systems. Divided energy electrochemical cells and electrochemical cell systems include a first electrochemical cell and a second electrochemical cell connected in parallel. Both electrochemical cells include a cathode disposed on a cathode current collector, an anode disposed on an anode current collector, and a separator disposed between the anode and the cathode. In some embodiments, the first electrochemical cell can have different performance properties from the second electrochemical cell. For example, the first electrochemical cell can have a high energy density while the second electrochemical cell can have a high power density. In some embodiments, the first electrochemical cell can have a battery chemistry, thickness, or any other physical/chemical property different from those properties of the second electrochemical cell.

TECHNICAL FIELD

Embodiments described herein relate to electrochemical cells and electrochemical cell systems having divided energy systems, and methods of making the same.

BACKGROUND

A battery or an electrochemical cell typically includes a single anode and a single cathode, each with one set of performance-related properties (e.g., capacity, power, thickness, chemistry). Cells with a single anode and a single cathode can often have performance properties that are excellent in some areas, but lacking in other areas. For example, a cell can have high energy density but low power density. In some cases, a cell can operate with high power density, but also have high heat generation. An enduring challenge is to create energy systems with complementary operational properties, such that a desired energy and power can be delivered to a system.

SUMMARY

Embodiments described herein relate to divided energy electrochemical cells and electrochemical cell systems. Divided energy electrochemical cells and electrochemical cell systems include a first electrochemical cell and a second electrochemical cell connected in parallel. Both electrochemical cells include a cathode disposed on a cathode current collector, an anode disposed on an anode current collector, and a separator disposed between the anode and the cathode. In some embodiments, the cathode current collector of the first electrochemical cell can also function as the cathode current collector of the second electrochemical cell. In some embodiments, the first electrochemical cell can have different performance properties from the second electrochemical cell. For example, the first electrochemical cell can have a high energy density while the second electrochemical cell can have a high power density. In some embodiments, the first electrochemical cell can have a battery chemistry, thickness, or any other physical/chemical property different from those properties of the second electrochemical cell. For example, the first electrochemical cell can have a first cathode chemistry (e.g., lithium iron phosphate), while the second electrochemical cell can have a second cathode chemistry (lithium nickel manganese cobalt oxide) different from the first cathode chemistry. In some embodiments, the anode and/or the cathode of the first electrochemical cell and/or the second electrochemical cell can be a semi-solid, binderless electrode. In some embodiments, the electrochemical cell system can include a third electrochemical cell or any number of additional electrochemical cells.

DETAILED DESCRIPTION

Embodiments described herein relate to divided energy electrochemical cells and electrochemical cell systems, and methods of making the same. More specifically, divided energy electrochemical cells and electrochemical cell systems include multiple anodes and multiple cathodes with different performance properties. Electrochemical cells often perform well by some metrics, but are lacking by other metrics. By combining multiple cell properties in a single electrochemical cell system, the electrochemical cell system can have improved performance in a wider range of metrics. For example, an electrochemical cell system can utilize the high capacity of a cell with a thick cathode (e.g., a cathode that includes lithium iron phosphate) and an anode (e.g., an anode that is lithium metal) while utilizing the high power density of a cell with a thinner cathode (e.g., a cathode that includes lithium iron phosphate) and an anode (e.g., an anode that includes graphite). Connecting two such cells in parallel to an external circuit can deliver high power density or high energy density on demand.

FIG.1is a schematic illustration of an electrochemical cell system100with a divided energy design, according to an embodiment. The electrochemical cell system100includes a first electrochemical cell100aand a second electrochemical cell100b. The first electrochemical cell100aincludes a first anode110adisposed on a first anode current collector120a, a first cathode130adisposed on a first cathode current collector140a, and a first separator150adisposed between the first anode110aand the first cathode130a. The second electrochemical cell100bincludes a second anode110b. In some embodiments, the second anode110bcan be disposed on a second anode current collector120b. The second electrochemical cell100bincludes a second cathode130b. In some embodiments, the second electrochemical cell100bcan include a second cathode current collector140b. In some embodiments, the second cathode130bcan be disposed on the second cathode current collector140b. The second electrochemical cell100bincludes a second separator150bdisposed between the second anode110band the second cathode130b.

As shown, the electrochemical cell system100is arranged cathode-to-cathode in the parallel configuration and the second cathode current collector140bis an optional component of the electrochemical cell system100. In some embodiments, the second cathode130bcan be disposed on the first cathode current collector140a, such that the first cathode current collector140aacts as a cathode current collector for both the first electrochemical cell100aand the second electrochemical cell100b. In some embodiments, the second cathode130bcan be disposed on the second cathode current collector140b. In some embodiments, a first surface of the first cathode current collector140acan be coated with the first cathode130a, while a second surface of the first cathode current collector140acan be uncoated. In some embodiments, a first surface of the second cathode current collector140bcan be coated with the second cathode130b, while a second surface of the second cathode current collector140bcan be uncoated. In some embodiments, the second surface of the first cathode current collector140acan be coupled to the second surface of the second cathode current collector140b.

In some embodiments, the electrochemical cell system100can be arranged anode-to-anode in the parallel configuration (not shown). In some embodiments, when the electrochemical cell system100is arranged anode-to anode, the second anode current collector120bis an optional component of the electrochemical cell system100. In some embodiments, the second anode110bcan be disposed on the first anode current collector120a, such that the first anode current collector120aacts as an anode current collector for both the first electrochemical cell100aand the second electrochemical cell100b. In some embodiments, the second anode110bcan be disposed on the second anode current collector120b. In some embodiments, a first surface of the first anode current collector120acan be coated with the first anode110a, while a second surface of the first anode current collector120acan be uncoated. In some embodiments, a first surface of the second anode current collector120bcan be coated with the second anode110b, while a second surface of the second anode current collector120bcan be uncoated. In some embodiments, the second surface of the first anode current collector120acan be coupled to the second surface of the second anode current collector120b. In some embodiments, the first anode110acan have the same or substantially similar chemical composition to the second anode110b. In some embodiments, the first anode110acan be different from the second anode110b. In some embodiments, the first anode110acan be different from the second anode110bin chemical composition, thickness, density, porosity, and/or any other properties.

In some embodiments, the first electrochemical cell100acan be disposed in a first pouch (not shown) and the second electrochemical cell100bcan be disposed in a second pouch (not shown). In some embodiments, the first electrochemical cell100aand the second electrochemical cell100bcan be disposed in a single pouch.

In some embodiments, the first electrochemical cell100aand/or the second electrochemical cell100bcan be a high power density cell. In some embodiments, the first electrochemical cell100aand/or the second electrochemical cell100bcan be a high energy density cell. In some embodiments, the first electrochemical cell100aand/or the second electrochemical cell100bcan be a high energy density cell with high heat production. In some embodiments, the first electrochemical cell100aand/or the second electrochemical cell100bcan be a high energy density cell that performs with low efficiency at low temperatures. In some embodiments, the first electrochemical cell100aand/or the second electrochemical cell100bcan have high capacity retention. In some embodiments, the first electrochemical cell100acan be a high power density cell while the second electrochemical cell100bcan be a high energy density cell. In some embodiments, the first electrochemical cell100acan be a high energy density cell with high heat production while the second electrochemical cell100bcan be a high energy density cell that performs with low efficiency at low temperatures. In some embodiments, the first electrochemical cell100acan have a high energy density while the second electrochemical cell100bcan have high capacity retention.

In some embodiments, “high power density cell” can refer to an electrochemical cell with a cell specific power output of at least about 400 W/kg, at least about 450 W/kg, at least about 500 W/kg, at least about 550 W/kg, at least about 600 W/kg, or at least about 650 W/kg, or at least about 700 W/kg, inclusive of all values and ranges therebetween.

In some embodiments, “high energy density cell” can refer to an electrochemical cell with a cell specific energy density of at least about 250 W·h/kg when discharged at 1C, at least about 300 W·h/kg when discharged at 1C, at least about 350 W·h/kg when discharged at 1C, at least about 400 W·h/kg when discharged at 1C, or at least about 450 W·h/kg when discharged at 1C, inclusive of all values and ranges therebetween In some embodiments, “high energy density cell” can refer to an electrochemical cell with a specific energy density of at least about 250 W·h/kg when discharged at C/2, at least about 300 W·h/kg when discharged at C/2, at least about 350 W·h/kg when discharged at C/2, at least about 400 W·h/kg when discharged at C/2, or at least about 450 W·h/kg when discharged at C/2, inclusive of all values and ranges therebetween In some embodiments, “high energy density cell” can refer to an electrochemical cell with a specific energy density of at least about 250 W·h/kg when discharged at C/4, at least about 300 W·h/kg when discharged at C/4, at least about 350 W·h/kg when discharged at C/4, at least about 400 W·h/kg when discharged at C/4, or at least about 450 W·h/kg when discharged at C/4, inclusive of all values and ranges therebetween.

In some embodiments, “cell with high heat production” can refer to an electrochemical cell, wherein at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, or at least about 50% of the energy generated is lost as heat, inclusive of all values and ranges therebetween.

In some embodiments, a “cell that performs with low efficiency at low temperatures” can refer to a cell that loses at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or about 100% of its discharge capacity when operated at −20° C., as compared to operation at room temperature, inclusive of all values and ranges therebetween.

In some embodiments, “high capacity retention” can refer to an electrochemical cell that retains at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% of its initial discharge capacity after 1,000 cycles, inclusive of all values and ranges therebetween.

In some embodiments, the first anode110aand/or the second anode110a(collectively referred to as anodes110) can include graphite, lithium metal (Li), sodium metal (Na), silicon oxide (SiO), graphite, silicon, carbon, lithium-intercalated carbon, lithium nitrides, lithium alloys, lithium alloy forming compounds, or any other anode active material, inclusive of all combinations thereof. In some embodiments, the lithium alloy forming compounds can include silicon, bismuth, boron, gallium, indium, zinc, tin, antimony, aluminum, titanium oxide, molybdenum, germanium, manganese, niobium, vanadium, tantalum, gold, platinum, iron, copper, chromium, nickel, cobalt, zirconium, yttrium, molybdenum oxide, germanium oxide, silicon carbide, silicon-graphite composite. In some embodiments, the first cathode130aand/or the second cathode130b(collectively referred to as cathodes130) can include Lithium cobalt oxide (LCO), lithium nickel manganese cobalt oxide (NMC), lithium iron phosphate (LFP), or any other cathode active material, inclusive of all combinations thereof. In some embodiments, the first electrochemical cell100aand/or the second electrochemical cell100bcan include one or more electrolyte solutions. Electrolyte solutions can include ethylene carbonate (EC), gamma-butyrolactone (GBL), Lithium bis(fluorosulfonyl) imide (LiFSI), trioctyl phosphate (TOP), propylene carbonate (PC), dimethoxyethane (DME), bis(trifluoromethanesulfonyl)imide (TSFI), Li1.4Al0.4Ti1.6(PO4)3(LATP), and any combinations thereof. Additional examples of active materials, conductive materials, and electrolyte solutions that can be incorporated in the first electrochemical cell100aand/or the second electrochemical cell100bare described in U.S. Pat. No. 9,484,569, entitled, “Electrochemical Slurry Compositions and Methods of Preparing the Same,” (“the '569 patent”) and in U.S. Pat. No. 9,437,864 entitled, “Asymmetric Battery Having a Semi-Solid Cathode and High Energy Density Anode,” registered Sep. 6, 2016 (“the '864 patent), the disclosures of which are incorporated herein by reference in their entirety.

In some embodiments, the first separator150aand/or the second separator150b(collectively referred to as separators150) can include a selectively permeable membrane, such that the anodes110and cathodes130are fluidically and/or chemically isolated from each other. This can allow for independent optimization of the properties of each of the electrodes. Examples of electrochemical cells that include a separator with a selectively permeable membrane that can chemically and/or fluidically isolate the anode from the cathode while facilitating ion transfer during charge and discharge of the cell are described in U.S. Patent Publication No. 2019/0348705, entitled, “Electrochemical Cells Including Selectively Permeable Membranes, Systems and Methods of Manufacturing the Same,” filed Jan. 8, 2019 (“the '705 publication”), the disclosure of which is incorporated herein by reference in its entirety.

In some embodiments, the first anode110aand/or the second anode110bcan be a semi-solid electrode. In some embodiments, the first cathode130aand/or the second cathode130bcan be a semi-solid electrode. In comparison to conventional electrodes, semi-solid electrodes can be made (i) thicker (e.g., greater than about 250 μm-up to about 2,000 μm or even greater) due to the reduced tortuosity and higher electronic conductivity of semi-solid electrodes, (ii) with higher loadings of active materials, (iii) with a simplified manufacturing process utilizing less equipment, and (iv) can be operated between a wide range of C-rates while maintaining a substantial portion of their theoretical charge capacity. These relatively thick semi-solid electrodes decrease the volume, mass and cost contributions of inactive components with respect to active components, thereby enhancing the commercial appeal of batteries made with the semi-solid electrodes. In some embodiments, the semi-solid electrodes described herein, are binderless and/or do not use binders that are used in conventional battery manufacturing. Instead, the volume of the electrode normally occupied by binders in conventional electrodes, is now occupied, by: 1) electrolyte, which has the effect of decreasing tortuosity and increasing the total salt available for ion diffusion, thereby countering the salt depletion effects typical of thick conventional electrodes when used at high rate, 2) active material, which has the effect of increasing the charge capacity of the battery, or 3) conductive additive, which has the effect of increasing the electronic conductivity of the electrode, thereby countering the high internal impedance of thick conventional electrodes. The reduced tortuosity and a higher electronic conductivity of the semi-solid electrodes described herein, results in superior rate capability and charge capacity of electrochemical cells formed from the semi-solid electrodes. In some embodiments, the first cathode130acan have the same or substantially similar chemical composition to the second cathode130b. In some embodiments, the first cathode130acan be different from the second cathode130b. In some embodiments, the first cathode130acan be different from the second cathode130bin chemical composition, thickness, density, porosity, and/or any other properties.

Since the semi-solid electrodes described herein can be made substantially thicker than conventional electrodes, the ratio of active materials (i.e., the semi-solid cathode and/or anode) to inactive materials (i.e., the current collector and separator) can be much higher in a battery formed from electrochemical cell stacks that include semi-solid electrodes relative to a similar battery formed form electrochemical cell stacks that include conventional electrodes. This substantially increases the overall charge capacity and energy density of a battery that includes the semi-solid electrodes described herein. The use of semi-solid, binderless electrodes can also be beneficial in the incorporation of an overcharge protection mechanism, as generated gas can migrate to the electrode/current collector interface without binder particles inhibiting the movement of the gas within the electrode.

In some embodiments, the electrode materials described herein can be a flowable semi-solid or condensed liquid composition. A flowable semi-solid electrode can include a suspension of an electrochemically active material (anodic or cathodic particles or particulates), and optionally an electronically conductive material (e.g., carbon) in a non-aqueous liquid electrolyte. Said another way, the active electrode particles and conductive particles are co-suspended in a liquid electrolyte to produce a semi-solid electrode. Examples of electrochemical cells that include a semi-solid and/or binderless electrode material are described in U.S. Pat. No. 8,993,159 entitled, “Semi-solid Electrodes Having High Rate Capability,” registered Mar. 31, 2015 (“the '159 patent”), the disclosure of which is incorporated herein by reference in its entirety.

In some embodiments, the first electrochemical cell100aand/or the second electrochemical cell100bcan include conventional electrodes (e.g., solid electrodes with binders). In some embodiments, the thickness of the conventional electrodes can be in the range of about 20 μm to about 100 μm, about 20 μm to about 90 μm, about 20 μm to about 80 μm, about 20 μm to about 70 μm, about 20 μm to about 60 μm, about 25 μm to about 60 μm, about 30 μm to about 60 μm, about 20 μm to about 55 μm, about 25 μm to about 55 μm, about 30 μm to about 55 μm, about 20 μm to about 50 μm, about 25 μm to about 50 μm, or about 30 μm to about 50 μm, inclusive of all values and ranges therebetween. In some embodiments, the thickness of the conventional electrodes can be about 20 μm, about 25 μm, about 30 μm, about 35 μm, about 40 μm, about 45 μm, about 50 μm, about 55 μm, or about 60 μm, inclusive of all values and ranges therebetween.

In some embodiments, the first anode110aand/or the second anode110bcan have a thickness of at least about 20 μm, at least about 30 μm, at least about 40 μm, at least about 50 μm, at least about 60 μm, at least about 70 μm, at least about 80 μm, at least about 90 μm, at least about 100 μm, at least about 110 μm, at least about 120 μm, at least about 130 μm, or at least about 140 μm. In some embodiments, the first anode110aand/or the second anode110bcan have a thickness of no more than about 150 μm, no more than about 140 μm, no more than about 130 μm, no more than about 120 μm, no more than about 110 μm, no more than about 100 μm, no more than about 90 μm, no more than about 80 μm, no more than about 70 μm, no more than about 60 μm, no more than about 50 μm, or no more than about 30 μm. Combinations of the above-referenced thicknesses of the first anode110aand/or the second anode110bare also possible (e.g., at least about 20 μm and no more than about 150 μm or at least about 50 μm and no more than about 100 μm), inclusive of all values and ranges therebetween. In some embodiments, the first anode110aand/or the second anode110bcan have a thickness of about 20 μm, about 30 μm, about 40 μm, about 50 μm, about 60 μm, about 70 μm, about 80 μm, about 90 μm, about 100 μm, about 110 μm, about 120 μm, about 130 μm, about 140 μm, or about 150 μm.

In some embodiments, the second anode110bcan have a thickness the same or substantially similar to a thickness of the first anode110a. In some embodiments, the second anode110bcan have a thickness greater than the thickness of the first anode110a. In some embodiments, the second anode110bcan be thicker than the first anode110aby a factor of at least about 1, at least about 1.1, at least about 1.2, at least about 1.3, at least about 1.4, at least about 1.5, at least about 1.6, at least about 1.7, at least about 1.8, at least about 1.9, at least about 2, at least about 2.5, at least about 3, at least about 3.5, at least about 4, at least about 4.5, or at least about 5.

In some embodiments, the first cathode130aand/or the second cathode130bcan have a thickness of at least about 50 μm, at least about 60 μm, at least about 70 μm, at least about 80 μm, at least about 90 μm, at least about 100 μm, at least about 110 μm, at least about 120 μm, at least about 130 μm, at least about 140 μm, at least about 150 μm, at least about 200 μm, at least about 250 μm, at least about 300 μm, at least about 350 μm, at least about 400 μm, or at least about 450 μm. In some embodiments, the first cathode130aand/or the second cathode130bcan have a thickness of no more than about 500 μm, no more than about 450 μm, no more than about 400 μm, no more than about 350 μm, no more than about 300 μm, no more than about 250 μm, no more than about 200 μm, no more than about 150 μm, no more than about 140 μm, no more than about 130 μm, no more than about 120 μm, no more than about 110 μm, no more than about 100 μm, no more than about 90 μm, no more than about 80 μm, no more than about 70 μm, or no more than about 60 μm. Combinations of the above-referenced thicknesses of the first cathode130aand/or the second cathode130bare also possible (e.g., at least about 50 μm and no more than about 500 μm or at least about 100 μm and no more than about 300 μm), inclusive of all values and ranges therebetween. In some embodiments, the first cathode130aand/or the second cathode130bcan have a thickness of about 50 μm, about 60 μm, about 70 μm, about 80 μm, about 90 μm, about 100 μm, about 110 μm, about 120 μm, about 130 μm, about 140 μm, about 150 μm, about 200 μm, about 250 μm, about 300 μm, about 350 μm, about 400 μm, about 450 μm, or about 500 μm.

In some embodiments, the second cathode130bcan have a thickness the same or substantially similar to a thickness of the first cathode130a. In some embodiments, the second cathode130bcan have a thickness greater than the thickness of the first cathode130a. In some embodiments, the second cathode110bcan be thicker than the first cathode110aby a factor of at least about 1, at least about 1.1, at least about 1.2, at least about 1.3, at least about 1.4, at least about 1.5, at least about 1.6, at least about 1.7, at least about 1.8, at least about 1.9, at least about 2, at least about 2.5, at least about 3, at least about 3.5, at least about 4, at least about 4.5, or at least about 5.

In some embodiments, the first electrochemical cell100aand/or the second electrochemical cell100bcan have a thickness of at least about 100 μm, at least about 150 μm, at least about 200 μm, at least about 250 μm, at least about 300 μm, at least about 350 μm, at least about 400 μm, at least about 450 μm, at least about 500 μm, at least about 550 μm, at least about 600 μm, at least about 650 μm, at least about 700 μm, at least about 750 μm, at least about 800 μm, at least about 850 μm, at least about 900 μm, or at least about 950 μm. In some embodiments, the first electrochemical cell100aand/or the second electrochemical cell100bcan have a thickness of no more than about 1,000 μm, no more than about 950 μm, no more than about 900 μm, no more than about 850 μm, no more than about 800 μm, no more than about 750 μm, no more than about 700 μm, no more than about 650 μm, no more than about 600 μm, no more than about 550 μm, no more than about 500 μm, no more than about 450 μm, no more than about 400 μm, no more than about 350 μm, no more than about 300 μm, no more than about 250 μm, no more than about 200 μm, or no more than about 150 μm. Combinations of the above-referenced thicknesses of the first electrochemical cell100aand/or the second electrochemical cell100bare also possible (e.g., at least about 100 μm and no more than about 1,000 μm or at least about 200 μm and no more than about 500 μm), inclusive of all values and ranges therebetween. In some embodiments, the first electrochemical cell100aand/or the second electrochemical cell100bcan have a thickness of about 100 μm, about 150 μm, about 200 μm, about 250 μm, about 300 μm, about 350 μm, about 400 μm, about 450 μm, about 500 μm, about 550 μm, about 600 μm, about 650 μm, about 700 μm, about 750 μm, about 800 μm, about 850 μm, about 900 μm, about 950 μm, or about 1,000 μm.

In some embodiments, the second electrochemical cell100bcan have a thickness the same or substantially similar to a thickness of the first electrochemical cell100a. In some embodiments, the second electrochemical cell100bcan have a thickness greater than the thickness of the first electrochemical cell100a. In some embodiments, the second electrochemical cell100bcan be thicker than the first electrochemical cell100aby a factor of at least about 1, at least about 1.1, at least about 1.2, at least about 1.3, at least about 1.4, at least about 1.5, at least about 1.6, at least about 1.7, at least about 1.8, at least about 1.9, at least about 2, at least about 2.5, at least about 3, at least about 3.5, at least about 4, at least about 4.5, or at least about 5.

In some embodiments, the electrochemical cell system100can have a first internal resistance (IR). In some embodiments, the first electrochemical cell100acan have a second IR when operated individually and the second electrochemical cell100bcan have a third IR when operated individually. In some embodiments, the first IR can be less than the minimum of the second IR and the third IR by at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, or at least about 60%, inclusive of all values and ranges therebetween.

In some embodiments, the electrochemical cell system100can have self-heating properties. For example, the IR of the first electrochemical cell100acan be greater than the IR of the second electrochemical cell100b, such that a temperature of the first electrochemical cell100acan increase during operation more than a temperature of the second electrochemical cell100b. Heat can then transfer from the first electrochemical cell100ato the second electrochemical cell100bto increase reaction rates and diffusivity in the second electrochemical cell100b.

In some embodiments, the electrochemical cell system100can include a third electrochemical cell (not shown). In some embodiments, the electrochemical cell system100can include 4, 5, 6, 7, 8, 9, 10 or more electrochemical cells. In some embodiments, a selection of many different battery properties can be combined into the electrochemical cell system100in order to manipulate the performance properties of the electrochemical cell system100as desired.

The term “substantially” when used in connection with “cylindrical,” “linear,” and/or other geometric relationships is intended to convey that the structure so defined is nominally cylindrical, linear or the like. As one example, a portion of a support member that is described as being “substantially linear” is intended to convey that, although linearity of the portion is desirable, some non-linearity can occur in a “substantially linear” portion. Such non-linearity can result from manufacturing tolerances, or other practical considerations (such as, for example, the pressure or force applied to the support member). Thus, a geometric construction modified by the term “substantially” includes such geometric properties within a tolerance of plus or minus 5% of the stated geometric construction. For example, a “substantially linear” portion is a portion that defines an axis or center line that is within plus or minus 5% of being linear.

As used herein, the term “set” and “plurality” can refer to multiple features or a singular feature with multiple parts. For example, when referring to a set of electrodes, the set of electrodes can be considered as one electrode with multiple portions, or the set of electrodes can be considered as multiple, distinct electrodes. Additionally, for example, when referring to a plurality of electrochemical cells, the plurality of electrochemical cells can be considered as multiple, distinct electrochemical cells or as one electrochemical cell with multiple portions. Thus, a set of portions or a plurality of portions may include multiple portions that are either continuous or discontinuous from each other. A plurality of particles or a plurality of materials can also be fabricated from multiple items that are produced separately and are later joined together (e.g., via mixing, an adhesive, or any suitable method).

As used herein, the term “about” and “approximately” generally mean plus or minus 10% of the value stated, e.g., about 250 μm would include 225 μm to 275 μm, about 1,000 μm would include 900 μm to 1,100 μm.

As used herein, the term “semi-solid” refers to a material that is a mixture of liquid and solid phases, for example, such as a particle suspension, a slurry, a colloidal suspension, an emulsion, a gel, or a micelle.

As used herein, the term “conventional separator” means an ion permeable membrane, film, or layer that provides electrical isolation between an anode and a cathode, while allowing charge-carrying ions to pass therethrough. Conventional separators do not provide chemical and/or fluidic isolation of the anode and cathode.

Typical current collectors for lithium cells include copper, aluminum, or titanium for the negative current collector and aluminum for the positive current collector, in the form of sheets or mesh, or any combination thereof. Current collector materials can be selected to be stable at the operating potentials of the positive and negative electrodes of electrochemical cells100aand100b. For example, in non-aqueous lithium systems, the first cathode current collector140aand/or the second cathode current collector140b(collectively referred to as cathode current collectors140) can include aluminum, or aluminum coated with conductive material that does not electrochemically dissolve at operating potentials of 2.5-5.0V with respect to Li/Li+. Such materials include platinum, gold, nickel, conductive metal oxides such as vanadium oxide, and carbon. The first anode current collector120aand/or the second anode current collector120b(collectively referred to as anode current collectors120) can include copper or other metals that do not form alloys or intermetallic compounds with lithium, carbon, and/or coatings comprising such materials disposed on another conductor.

FIG.2is a schematic illustration of an electrochemical cell system200with a divided energy design, according to an embodiment. The electrochemical cell system200includes a first electrochemical cell200aand a second electrochemical cell200b. As shown, both the first electrochemical cell200aand the second electrochemical cell200bare disposed in a single pouch260. In some embodiments, the first electrochemical cell200acan be physically coupled to the second electrochemical cell200b. In some embodiments, the first electrochemical cell200aand the second electrochemical cell can share a common anode current collector (not shown) or a common cathode current collector (not shown). In some embodiments, the first electrochemical cell200acan have a first battery chemistry and the second electrochemical cell200bcan have a second battery chemistry, different from the first battery chemistry. In some embodiments, the first electrochemical cell200aand the second electrochemical cell200bcan be the same or substantially similar to the first electrochemical cell100aand the second electrochemical cell100bas described above with reference toFIG.1.

FIG.3is a schematic illustration of an electrochemical cell system300with a divided energy design, according to an embodiment. The electrochemical cell system300includes a first electrochemical cell300aand a second electrochemical cell300b. As shown, the first electrochemical cell300ais disposed in a first pouch360aand the second electrochemical cell300bis disposed in a second pouch360b. In some embodiments, the first electrochemical cell300aand the second electrochemical cell300bcan be connected in parallel. In some embodiments, the first electrochemical cell300acan have a first battery chemistry and the second electrochemical cell300bcan have a second battery chemistry, different from the first battery chemistry. In some embodiments, the first electrochemical cell300aand the second electrochemical cell300bcan be the same or substantially similar to the first electrochemical cell100aand the second electrochemical cell100bas described above with reference toFIG.1.

FIGS.4A-4Eillustrate an electrochemical cell system400with a divided energy design, according to an embodiment. The electrochemical cell system400includes a first anode410adisposed on a first anode current collector420a, a second anode410bdisposed on a second anode current collector420b, a first cathode430adisposed on a cathode current collector440, a second cathode430bdisposed on the current collector440, a first separator450adisposed between the first anode410aand the first cathode430a, and a second separator450bdisposed between the second anode410band the second cathode430b. The first anode current collector420aincludes a first anode weld tab425a, the second anode current collector420bincludes a second anode weld tab425b, and the cathode current collector440includes a cathode weld tab445. Each of the aforementioned components is disposed in a single pouch460. In some embodiments, the first anode weld tab425aand the second anode weld tab425bcan be on the same side of the electrochemical cell system400, as depicted inFIGS.4A-4E.FIG.4Bis an auxiliary view of the electrochemical cell system400with surface A oriented through the first anode weld tab425aand the second anode weld tab425b, whileFIG.4Cis a cross-sectional view along surface A.FIG.4Dis an auxiliary view of the electrochemical cell system400with surface B oriented through the cathode weld tab445, whileFIG.4Eis a cross-sectional view along surface B.

In some embodiments, the first anode410a, second anode410b, first anode current collector420a, second anode current collector420b, first cathode430a, second cathode430b, cathode current collector440, first separator450a, and the second separator450b, can have the same or substantially similar properties to the first anode110a, second anode110b, first anode current collector120a, second anode current collector120b, first cathode130a, second cathode130b, cathode current collector140a, first separator150a, and the second separator150bas described above with reference toFIG.1. As shown, the second anode410bhas a thickness greater than the thickness of the first anode410aand the second cathode430bhas a thickness greater than a thickness of the first cathode430a. In some embodiments, the thickness of the second anode410bcan be the same or substantially similar to the thickness of the first anode410a. In some embodiments, the thickness of the second cathode430bcan be the same or substantially similar to the thickness of the first cathode430a. As shown, the edges of the cathode current collector440extend beyond the edges of the first cathode430aand the second cathode430band bond to the first separator450aand the second separator450b. This creates fluidic isolation between the first cathode430aand the second cathode430b. With this fluidic isolation, the first cathode430acan include a first electrolyte solution while the second cathode430bcan include a second electrolyte solution, wherein the second electrolyte solution is different from the first electrolyte solution. In some embodiments, the edges of the cathode current collector440can be flush with the edges of the first cathode430aand the second cathode430b, such that the first cathode430aand the second cathode430bare in fluidic communication.

FIGS.5A-5Eillustrate an electrochemical cell system500with a divided energy design, according to an embodiment. The electrochemical cell system500includes a first anode510adisposed on a first anode current collector520a, a second anode510bdisposed on a second anode current collector520b, a first cathode530adisposed on a cathode current collector540, a second cathode530bdisposed on the current collector540, a first separator550adisposed between the first anode510aand the first cathode530a, and a second separator disposed550bbetween the second anode510band the second cathode530b. The first anode current collector520aincludes a first anode weld tab525a, the second anode current collector520bincludes a second anode weld tab525b, and the cathode current collector540includes a cathode weld tab545. Each of the aforementioned components is disposed in a single pouch560. In some embodiments, the first anode weld tab525aand the second anode weld tab525bcan be on the opposite side of the electrochemical cell system500, as depicted inFIGS.5A-5E. In some embodiments, the first anode weld tab525aand the cathode weld tab545can be on the same side of the electrochemical cell system500, as depicted inFIGS.5A-5E.FIG.5Bis an auxiliary view of the electrochemical cell system500with surface A oriented through the second anode weld tab525b, whileFIG.5Cis a cross-sectional view along surface A.FIG.5Dis an auxiliary view of the electrochemical cell system500with surface B oriented through the first anode weld tab525aand the cathode weld tab545, whileFIG.5Eis a cross-sectional view along surface B. As shown, surface B is oriented through both the first anode weld tab525aand the cathode weld tab545. In some embodiments, the cathode weld tab545can be positioned such that surface A inFIG.5Bis oriented through the cathode weld tab545and the second anode weld tab525b. In some embodiments, the cathode weld tab545can be positioned closer to the middle of the cathode current collector540, such that neither surface A nor surface B are oriented through the cathode weld tab545.

In some embodiments, the first anode510a, second anode510b, first anode current collector520a, second anode current collector520b, first cathode530a, second cathode530b, cathode current collector540, first separator550a, and the second separator550b, can have the same or substantially similar properties to the first anode110a, second anode110b, first anode current collector120a, second anode current collector120b, first cathode130a, second cathode130b, cathode current collector140a, first separator150a, and the second separator150bas described above with reference toFIG.1. As shown, the second anode510bhas a thickness greater than a thickness of the first anode510aand the second cathode530bhas a thickness greater than a thickness of the first cathode530a. In some embodiments, the thickness of the second anode510bcan be the same or substantially similar to the thickness of the first anode510a. In some embodiments, the thickness of the second cathode530bcan be the same or substantially similar to the thickness of the first cathode530a. As shown, the edges of the cathode weld tab540extend beyond the edges of the first cathode530aand the second cathode530b. In some embodiments, the edges of the cathode weld tab540can be flush with the edges of the first cathode530aand the second cathode530b.

In addition, the disclosure may include other innovations not presently described. Applicant reserves all rights in such innovations, including the right to embodiment such innovations, file additional applications, continuations, continuations-in-part, divisional s, and/or the like thereof. As such, it should be understood that advantages, embodiments, examples, functional, features, logical, operational, organizational, structural, topological, and/or other aspects of the disclosure are not to be considered limitations on the disclosure as defined by the embodiments or limitations on equivalents to the embodiments. Depending on the particular desires and/or characteristics of an individual and/or enterprise user, database configuration and/or relational model, data type, data transmission and/or network framework, syntax structure, and/or the like, various embodiments of the technology disclosed herein may be implemented in a manner that enables a great deal of flexibility and customization as described herein.

The indefinite articles “a” and “an,” as used herein in the specification and in the embodiments, unless clearly indicated to the contrary, should be understood to mean “at least one.”

While specific embodiments of the present disclosure have been outlined above, many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, the embodiments set forth herein are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the disclosure. Where methods and steps described above indicate certain events occurring in a certain order, those of ordinary skill in the art having the benefit of this disclosure would recognize that the ordering of certain steps may be modified and such modification are in accordance with the variations of the invention. Additionally, certain of the steps may be performed concurrently in a parallel process when possible, as well as performed sequentially as described above. The embodiments have been particularly shown and described, but it will be understood that various changes in form and details may be made.

Comparative Example 1

A comparative electrochemical cell Example 1 (also referred to as “Comp Ex 1”) was prepared using a semi-solid LFP cathode and a semi-solid anode was formed from mesophase graphite powder (MGP) and C45 Ketjen carbon black. The semi-solid cathode was prepared by ball milling LFP for 48 hours and mixing with ECP600JD carbon and a non-aqueous electrolyte with 0.5 wt % Lithium bis(oxalato)borate (LiBOB). The semi-solid cathode was mixed at a mixing ratio of 48.95 vol % LFP, 1.05 vol % EPC600JD, and 50 vol % electrolyte. The semi-solid anode was prepared by milling MGP and C45 at a weight ratio of 50/2 MGP/C45 for 1 hour. The resulting mixed powder was then mixed with a non-aqueous electrolyte with 0.5 wt % LiBOB at a mixing ratio of 62 vol % powder to 38 vol % electrolyte. The semi-solid anode and the semi-solid cathode were both densified by being placed under a pressure of 6,000 psi, five times. The semi-solid anode and the semi-solid cathode were placed on either side of a separator to form an electrochemical cell. The electrochemical cell had a cathode thickness 1.32 times the thickness of the anode, and the total thickness of the electrochemical cell was 120 μm. The electrochemical cell was then placed in a pouch. The electrochemical cell was charged using a constant current-constant voltage with a constant current rate at C/20. The electrochemical cell was discharged at C/10. The electrochemical cell was initially charged and discharged 3 times.

Comparative Example 2

A comparative electrochemical cell Example 2 (also referred to as “Comp Ex 2”) was prepared using a semi-solid LFP cathode and a semi-solid anode was formed from mesophase graphite powder (MGP) and C45 Ketjen carbon black. The semi-solid cathode was prepared by ball milling LFP for 48 hours and mixing with ECP600JD carbon and a non-aqueous electrolyte with 0.5 wt % Lithium bis(oxalato)borate (LiBOB). The semi-solid cathode was mixed at a mixing ratio of 48.95 vol % LFP, 1.05 vol % EPC600JD, and 50 vol % electrolyte. The semi-solid anode was prepared by milling MGP and C45 at a weight ratio of 50/2 MGP/C45 for 1 hour. The resulting mixed powder was then mixed with a non-aqueous electrolyte with 0.5 wt % LiBOB at a mixing ratio of 62 vol % powder to 38 vol % electrolyte. The semi-solid anode and the semi-solid cathode were both densified by being placed under a pressure of 6,000 psi, five times. The semi-solid anode and the semi-solid cathode were placed on ether side of a separator to form an electrochemical cell. The electrochemical cell had a cathode thickness 1.32 times the thickness of the anode, and the total thickness of the electrochemical cell was 360 μm. The electrochemical cell was then placed in a pouch. The electrochemical cell was charged using a constant current-constant voltage with a constant current rate at C/20. The electrochemical cell was discharged at C/10. The electrochemical cell was initially charged and discharged 3 times.

A bi-cell Example 1 (also referred to as “Ex 1”) was prepared by stacking the Comp Ex 1 electrochemical cell on top of the Comp Ex 2 Electrochemical cell inside of a single pouch, connecting in series.

A bi-cell Example 2 (also referred to as “Ex 2”) was prepared by placing the Comp Ex 1 electrochemical cell into a first pouch and placing the Comp Ex 2 electrochemical cell into a second pouch and connecting the two electrochemical cells in parallel.

FIGS.6A-6Jshow Ragone plots of Ex 1, Ex 2, Comp Ex 1, and Comp Ex 2 at various states of charge (SOC).FIG.6A,FIG.6B,FIG.6C,FIG.6D,FIG.6E,FIG.6F,FIG.6G,FIG.6H,FIG.6I, andFIG.6Jshow Ragone plots at 100% SOC, 90% SOC, 80% SOC, 70% SOC, 60% SOC, 50% SOC, 40% SOC, 30% SOC, 20% SOC, and 10% SOC, respectively. As can be seen from these plots, the bi-cells have power densities similar to the thinner single cells, and energy density similar to the thicker cells. In other words, the divided energy systems can lead to combinations of power density and energy density not seen in single electrochemical cells.