Patent Publication Number: US-2022238889-A1

Title: Battery and method of making a battery

Description:
FIELD OF THE INVENTION 
     The invention relates to the field of batteries, inter alia Lithium Ion batteries. 
     BACKGROUND OF THE INVENTION 
     Lithium Ion batteries have become the work horse for many energy storage systems, from lap top computers to electric motor vehicles. A typical Li Ion battery with a graphite anode (negative electrode) has high coulombic efficiency, good cycle performance, low internal resistance with low self-discharge, does not suffer from memory effect, has a wide operating voltage range, and a long life. However, it suffers from low energy capacity. 
     The anode plays a significant role in improving the performance of a Li Ion battery. Traditional graphite anodes have a specific capacity close to the theoretical value of 372 mA/g. Therefore, any attempt to increase the energy capacity requires that one consider using different materials. 
     One approach that has been investigated in the past is the use of different materials for the anode of the Li Ion battery. Silicon, with a theoretical capacity of 3590 mAh/g has almost a ten times higher theoretical capacity compared to graphite. Thus it would be a valuable material for use in the anode. However, it has several drawbacks. Firstly, it displays low electrical conductivity. Secondly, it suffers from large volume changes during cycling, which are of the order of 300%. And thirdly, because of the repeated volume changes, it displays instability of the SEI layer. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to addressing some of the challenges faced by the battery industry. 
     In particular, the present invention defines and describes a method and battery using alternative anode materials, while addressing the risk of an explosion or other breakdown of the battery during use. 
     In order to address the low conductivity of Silicon, the present invention makes use of Silicon Dioxide (SiO2) or other conductive forms of silicon. 
     Further, the energy capacity of the battery depends on the surface area of the anode and cathode. Hence, the present invention increases the surface area of the anode material by making use of particularized material or silicon-based material in powder form. This may comprise SiO2 powder, also referred to herein as SiO2 nanoparticles. 
     Electrolyte is interspersed between the SiO2 nanoparticles, and can be in liquid form, seeping in between the SiO2 nanoparticles when assembled, or can be in granular/powder form itself, in which case it can be interspersed between the SiO2 during manufacture. 
     According to the invention, there is provided a battery, e.g., a Lithium Ion battery, comprising an anode, a cathode, and a separator between the anode and the cathode, wherein the anode is made of particularized Silicon Dioxide (SiO2) and includes means for accommodating the expansion of the SiO2. 
     The SiO2 may comprise nanoparticles contained in one or more housings to define one or more anodes interspersed between multiple cathodes or formed within a cathode to form one or more cells of a battery. The anodes, each comprising SiO2 anode material retained in an anode housing, may be electrically connected to each other. The cathodes, which typically will be interspersed or otherwise placed in proximity with the anodes, may similarly be electrically connected to each other. 
     The cathode may comprise a solid cathode material shaped to define an anode housing. The cathode may be substantially cylindrical with a conical cavity for receiving granular anode material such as SiO2. An expansion region may be provided at the wide end of the conical cavity. 
     Each anode and each cathode may be electrically connected to a current collector, which in the case of the anode may be a copper mesh, and in the case of the cathode, may be an aluminum mesh. By choosing a particularized anode material (in this case SiO2), the anode material is not fixed to the current collector but remains in physical contact with the current collector even when the anodes expand or contract. 
     To ensure good electrical contact between the anode material and current collector, the anode material may be compressed in its anode housings. 
     The housings containing the SiO2 particles (also referred to herein as anode housings) may have angled walls. For example, the walls of each housing may define a wedge-shaped or cone-shaped anode housing. 
     The anode and cathode housings may be defined by a porous separator, e.g., a porous membrane between the anode housings and cathode housings. The anode and cathode housings may instead comprise individual structures that each includes a current collector. These anode and cathode housings may subsequently be assembled to form multiple cells of a battery. The anode housings and cathode housings may be alternatingly stacked together. 
     Each anode housing or group of anode housings may include an expansion region or may be connected to an expansion means. The expansion region may be integrally formed with the anode housing, or may form a separate housing in flow communication with the anode housing to allow SiO2 particles to flow into the expansion region or expansion means. The expansion region may include a cylindrical housing with a piston, or a housing with a flexible wall, e.g. a latex membrane, to accommodate expansion of SiO2 particles. The expansion means may also include a flexible membrane covering an opening in the anode housing. For ease of description, the various expansion regions, membranes, or bladders, will also be referred to herein generally as expansion means. 
     One or more expansion means are preferably located on the wide side of the wedge-shaped or cone-shaped anode housing(s). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a three-dimensional few of one embodiment of a set of anode housings of the present invention, 
         FIG. 2  shows a three-dimensional view of the anode housings of  FIG. 1  and corresponding cathode housings that make up one embodiment of a Li Ion battery of the present invention, 
         FIG. 3  shows a three-dimensional view of the anode and cathode housings of  FIG. 2  intermeshed to form one embodiment of a Li Ion battery of the present invention, 
         FIG. 4  shows a three-dimensional view of another embodiment of a Li Ion battery of the present invention, 
         FIG. 5 , shows a three-dimensional view of the embodiment of  FIG. 4  from a different direction, 
         FIG. 6 , shows a three-dimensional view of part of the embodiment of  FIG. 4 , 
         FIG. 7  shows a three-dimensional view of a variation of the Li Ion battery embodiment of  FIG. 4 , 
         FIG. 8  shows a three-dimensional view of yet another embodiment of a Li Ion battery of the present invention, 
         FIG. 9 , shows a detailed three-dimensional view of one end of the embodiment of  FIG. 8 , 
         FIG. 10 , shows a three-dimensional view of the embodiment of  FIG. 8  from the end depicted in  FIG. 9 , with the addition of expansion means, 
         FIG. 11 , shows a three-dimensional view of the embodiment of  FIG. 8  from the opposite direction of  FIG. 9 , 
         FIGS. 12-15  show parts of anode and cathode housings of the embodiment of  FIG. 8 ; 
         FIG. 16  shows a three-dimensional sectional view of the embodiment of  FIG. 8 , 
         FIG. 17  shows a three-dimensional view of yet another embodiment of a Li Ion battery of the present invention, and 
         FIG. 18  shows a sectional side view of the embodiment of  FIG. 17 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     One embodiment of a Lithium Ion battery of the present invention is shown in  FIGS. 1-3 .  FIG. 1  shows a matrix of anodes, each defined by a cone-shaped anode housing  100 , terminating in an expansion region  102  and a flexible end cap  104 . Particularized (granular) Silicon Dioxide (SiO2)  110  is used as the anode material, and is packed into the anode housings to ensure that the particles of SiO2 are conductively connected to each other. 
     By making use of a cone-shaped anode housing for each anode, any expansion of the SiO2  110  will cause it to be forced longitudinally downward in a direction along the longitudinal axis  112  of the cone-shaped housing  100 . The expansion regions  102  in this embodiment are cylindrical sections housing a piston (not shown) that travels within the cylinder and allows the SiO2 to expand and contract. 
     In order to electrically connect the anodes to a common negative electrode, each anode includes a current collector (not shown in this embodiment but discussed with respect to the embodiment of  FIG. 9  and the embodiment of  FIG. 16 ), which may take the form of a copper mesh, running longitudinally within the anode housing  100  along the longitudinal axis  112 . Thus. any movement of the granular SiO2 material longitudinally will nevertheless maintain electrical contact with the current collector. The current collectors are in turn electrically connected together and connected to a negative electrode. The cathodes in the cathode housings are similarly provided with current collectors, e.g. Aluminum mesh, and connected to each other and a common positive electrode. 
       FIG. 2  shows the matrix of anode housings  100 , depicted generally as the anode  120  of a battery prior to assembly. A corresponding matrix of cathode housings defines the cathode  220 . 
     As shown in  FIG. 3 , the anode and cathode housings are staggered relative to each other allowing the two matrices (anode cells  300  and cathode cells  302 ) to slot together to define an anode-cathode matrix of interspersed anode cones and cathode cones, forming multiple cells of a battery. 
     The cone-shaped walls of the anode and cathode housings are made of a permeable material having tiny openings for ions to pass through but small enough to avoid the particulate SiO2 material of the anodes from seeping out through the cone-shaped walls of the anode housings. In embodiments where a liquid electrolyte is used for ion transport between the anodes and cathodes, the electrolyte seeps through the permeable housing walls of the anode and cathode housings to contact the individual nanoparticles of SiO2 in the anodes and the granular cathode particles in the cathodes. In embodiments where a granular solid is used for the electrolyte, electrolyte particles and anode particles are preferably mixed prior to packing the material into the anodes. Similarly, granular electrolyte and granular cathode material is mixed and packed into the cathodes. 
     It will be noted that the configuration of the cathode housings is similar to that described for the anode housings in this embodiment, however this is for convenience, compatibility, and ease of manufacturing. It will be appreciated that the cathode material typically does not expand, at least not to a significant degree. Hence the cone shape of the cathode housings is not for expansion purposes but to allow the anode and cathode cones to intersperse (mesh) when the anode cells  300 , and cathode cells  302  are fitted together. 
     In practice, the two sections with the anode cells  300 , and cathode cells  302  will be housed in a battery housing filled with an electrolyte (not shown). All of the anode elements (defined by the SiO2 in the anode housings  100 ) will be electrically connected to define the anode  120  of the battery, and are connected to a common negative electrode (not shown). Similarly, the cathode elements defined by the cathode material in the cathode housings, are electrically connected to define the cathode  220  of the battery, and are connected to a common positive electrode (not shown). 
     Another embodiment of a Li Ion battery of the present invention is shown in  FIGS. 4-6 . In this embodiment, as shown in  FIG. 4 , a housing  400  supports a set of pins  402 ,  412  (more clearly shown in  FIG. 6 ). The pins  402  on the one side  410  of the housing are staggered relative to the pins  412  on the other side  420  of the housing. This allows a porous membrane  430 , e.g., a porous polymer membrane (see also  FIG. 6 ) to be wound around the pins  402 ,  412  to form wedge-shaped structures within the housing  400 . 
     The wedges  440  with their wide section toward the left-hand side of the housing  400  as depicted in  FIG. 4  define anode housings and are filled with granular SiO2 to form wedge-shaped anodes. The granular SiO2 is also referred to herein as SiO2 nanoparticles since the grain structure is typically in the nanometer range. 
     The intervening wedges  450  with their wide end facing the right-hand side in  FIG. 4 , define cathode housings and are filled with cathode material as known in the art, to define wedge-shaped cathodes. In practice the wedge-shaped anodes are connected to together to define the anode of the battery, and are electrically connected to an anode electrode (negative electrode) depicted by electrode  460 . The wedge-shaped cathodes are connected to together to define the cathode of the battery, and are electrically connected to a cathode electrode (positive electrode) depicted by electrode  470 . 
     In this embodiment, cylindrical expansion chambers  480 ,  482  extend from the housing  400 . The expansion chambers are aligned with the wide ends of the wedge-shaped anodes and cathodes and are in flow communication with the anode and cathode material, respectively so that expansion of the anode material (SiO2) will allow the material to expand into the chambers  480 . Since the porous membrane  430  in this embodiment is flexible, pressure exerted laterally by expanding SiO2 particles can cause pressure on the cathode material. Hence the wedge-shaped cathodes  450  are also provided with expansion chambers  482  to allow flowable (e.g., particularized or granular) cathode material to be displaced from the wedge-shaped cathodes  450  in the housing  400  into the expansion chambers  482 . As in the embodiment of  FIG. 1 , the expansion chambers  480 ,  482  (also referred to herein as expansion regions or expansion means) are cylindrical in shape to accommodate pistons (not shown). Preferably the pistons in this embodiment and the  FIG. 1  embodiment are attached to springs that compress as the pistons move outward, thereby urging the pistons to move back inward, toward the housing  400  when the SiO2 material contracts. 
       FIG. 5  shows the housing  400  from the cathode end, showing the pistons  500  inside the expansion chambers  482 . For clarity, the compression springs in the expansion chambers  482  are not shown, nor are the end caps that in practice cover the outer openings of the expansion chambers  482 . The end caps, which cover the openings of the expansion chambers  482  when fully assembled, provide a surface for the compression springs to act against. 
     A variation of the  FIG. 4  embodiment is shown in  FIG. 7 . In this embodiment, only the anode is provided with expansion chambers or expansion regions  700 , and only two such regions are provided. Each expansion chamber  700  is provided with a piston  702  having O-rings  704  to provide a slidable seal between chamber wall and piston. 
     Yet another embodiment of a Li Ion battery of the present invention is shown in  FIGS. 8-16 . Again, this embodiment makes use of wedge-shaped anodes and cathodes, but in this case the wedge-shaped housings are not formed of a flexible membrane but are formed from a more rigid plastics material that is nevertheless porous for the passing of ions between the anode and cathodes. In the embodiment shown in  FIG. 8 , a single wedge-shaped anode housing  800  is shown wedged between two wedge-shaped cathode housings  802 . Again, the wide side of the anode includes expansion means, indicated generally by reference numeral  810 . In this embodiment, the expansion means comprises a termination wall  812 , shown more clearly in  FIG. 9 . The termination wall  812  includes a central opening  900  and a concave recess  902  flaring outwardly from the opening  900 . The opening  900  is in flow communication with the particulate SiO2 material that once again defines the anode and is housed in the anode housing  800 . Thus, during expansion of the SiO2 material, the SiO2 particles can extend into and through the opening  900 , passing into the concave recess region  902 . 
     Also shown in  FIG. 9  is a copper current collector mesh  910  for the anode, which will be discussed further below. 
     As shown in  FIG. 10 , a flexible membrane  1000  is used to cover the outer open end of the concave recess region  902 , and is secured by means of a mounting bracket  1002 . The flexible membrane  1000 , e.g. a latex membrane, permits additional expansion of the anode material and also provides a compressive force on the expanding material to urge it back into the anode housing when the SiO2 contracts. 
     The wide ends  820  of the wedge-shaped cathode housings  802  are also provided with a terminating wall  822 .  FIG. 11  shows an end view of the cathode terminating wall  822 . In this case the wall  822  presents a rectangular opening  1100 , which in practice is covered by a cover (not shown). 
     As shown in  FIG. 11 , each cathode is provided with a mesh  1110 , which in this case takes the form of aluminum meshes, acting as current collectors that are electrically connected to positive electrodes  1112 . 
     The anode is also provided with a current collector (depicted in  FIG. 9  by reference numeral  910 ), which in this case is defined by a copper mesh and is shown more clearly in  FIG. 16 . The copper mesh  910  electrically connects to a negative electrode, which is depicted in  FIGS. 8 and 10  by reference numeral  1114 . 
       FIGS. 12 to 15  provide a more detailed view of the wedge-shaped anode and cathode housings. The anode housing  800  (shown here in black) has a square horse-shoe configuration as shown in  FIG. 12 . The cathode housings  820  (one of which is shown here in white) similarly have a square horse-shoe configuration. Each wedge-shaped housing  800 ,  802 , thus defines a central wedge-shaped space  1200  for housing either anode material (SiO2 in this case) or cathode material. 
     Furthermore, the anode wedge-shaped housing  800  is made up of two sections (one of them is shown in  FIG. 13  and depicted by reference numeral  1300 ). The section  1300  has an outer peripheral lip  1310  so that when two such sections are placed face-to-face, they form a space between them that is open toward the central horse-shoe space  1200 . This space between the two sections receives the copper current collector mesh of the anode. Each cathode housing  802  is similarly made up of two sections, one of which is depicted by reference numeral  1320  in  FIG. 13 , and again has a peripheral lip  1330 . Again, the lip  1330  forms a space, which in this case receives the aluminum current collector mesh for the cathode. 
       FIG. 14  shows the anode housing  800  and one of the cathode housings  802  stacked on top of one another, as they would when being assembled to form a battery. In order to seal the central openings  1200  of the cathode horse-shoe structures, the top and bottom cathode housings  802  are sealed by means of top and bottom end caps  1500  as shown in  FIG. 15 . 
     As shown in  FIG. 16 , the anode housing  800  is separated from the cathode housings  802  by separators  1600 , which comprise permeable membranes. The copper mesh  910  of the anode, and the aluminum mesh  1110  of each cathode, are also shown in  FIG. 16 . It will be appreciated that  FIG. 16  shows the battery inverted compared to the depiction in  FIG. 8 . Thus, the end wall  812  on the wide side of the anode housing is on the right-hand side in this Figure, and the end wall  822  on the wide sides of the cathode housings is on the left side. The end wall  812  also shows the concave recess  902  with the central opening  902 , as well as the flexible membrane  1000 . 
     Referring again to  FIG. 8 , the battery in this embodiment includes air vent  880  for venting accumulated gas build up from the anode, and air vents  882  for venting accumulated gas build up from the cathodes. 
     Yet another embodiment of a Lithium Ion battery of the present invention is shown in  FIGS. 17 and 18 . In this embodiment, the cathode  1700  is formed from a solid material and shaped into a cylinder. As shown in the cross-section of  FIG. 18 , the cathode  1700  is provided with a conical cavity, which defines an anode housing and receives the particulate anode material (SiO2 in the present invention) to define the anode  1800 . The anode  1800  is provided with an expansion chamber  1802 , so that the SiO2 can expand into the expansion chamber. The expansion chamber  1802  can again be provided with a spring and piston arrangement (not shown) as discussed above with respect to the  FIG. 4  and  FIG. 7  embodiments. 
     While the present invention has been described with respect to specific embodiments, it will be appreciated that other configurations of the battery can be produced, without departing from the scope of the invention.