Systems and methods for high pressure assembly of electrochemical cells - Patents.com

Abstract

The embodiments described herein relate to electrochemical cells and their fabrication under high pressure. In some aspects, a method of fabricating an electrochemical cell can include disposing a cathode material on a cathode current collector to form a cathode, disposing an anode material on the anode current collector to form an anode, and disposing the anode on the cathode and a separator located between the anode and cathode in an assembly fixture to form an electrochemical cell, the assembly fixture applying a force to the electrochemical cell such that a pressure in the cathode material is at least about 3,500 kPa. In some embodiments, the cathode material can be a first cathode material, and the method can further include disposing a second cathode material on the first cathode material. In some embodiments, the first cathode material can include silicon. In some embodiments, the second cathode material can include graphite.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Application No. 63 / 302,622, entitled "Systems and Methods for High Pressure Assembly of Electrochemical Cells," filed January 25, 2022, the contents of which are incorporated by reference in their entirety herein.

[0002] The embodiments described herein relate to the fabrication of electrochemical cells under high pressure. [Background technology]

[0003] Electrochemical cells can be fabricated with multiple layers in the anode and / or cathode. However, gas can form and accumulate during the formation of the electrochemical cell. Gas can form within the electrodes, at the interfaces between the electrode layers, or at the interfaces between the electrodes and the separator. Solid electrolyte interfaces (SEIs) can also accumulate between the layers of the electrochemical cell. This can result in capacity loss during initial cycling of the cell and throughout subsequent cycling of the cell. Suppressing the formation of gas bubbles and SEIs can improve cell performance and cycling stability. Summary of the Invention

[0004] The embodiments described herein relate to electrochemical cells and their fabrication under high pressure. In some aspects, a method of fabricating an electrochemical cell can include disposing a cathode material on a cathode current collector to form a cathode, disposing an anode material on the anode current collector to form an anode, and disposing the anode on the cathode and a separator located between the anode and cathode in an assembly fixture to form an electrochemical cell, the assembly fixture applying a force to the electrochemical cell such that a pressure in the cathode material is at least about 3,500 kPa. In some embodiments, the cathode material can be a first cathode material, and the method can further include disposing a second cathode material on the first cathode material. In some embodiments, the first cathode material can include silicon. In some embodiments, the second cathode material can include graphite. In some embodiments, the assembly fixture can apply a force to the electrochemical cell such that the pressure within the cathode material is at least about 7,000 kPa or at least about 8,000 kPa. [Brief description of the drawings]

[0005] [Figure 1] FIG. 2 is a block diagram of a method for manufacturing an electrochemical cell according to an embodiment. [Diagram 2] FIG. 1 is a block diagram for an assembly fixture for manufacturing an electrochemical cell according to an embodiment. [Figure 3A] FIG. 2 is an explanatory diagram of an assembly jig for manufacturing an electrochemical cell according to an embodiment. [Figure 3B] FIG. 2 is an explanatory diagram of an assembly jig for manufacturing an electrochemical cell according to an embodiment. [Figure 3C] FIG. 2 is an explanatory diagram of an assembly jig for manufacturing an electrochemical cell according to an embodiment. [Figure 3D] FIG. 2 is an explanatory diagram of an assembly jig for manufacturing an electrochemical cell according to an embodiment. [Figure 4] FIG. 2 is an explanatory diagram of an assembly jig for manufacturing an electrochemical cell according to an embodiment. [Figure 5A] FIG. 2 is an illustration of an electrochemical cell stack manufactured using an assembly jig according to an embodiment. [Figure 5B] FIG. 2 is an illustration of an electrochemical cell stack manufactured using an assembly jig according to an embodiment. [Figure 5C] FIG. 2 is an illustration of an electrochemical cell stack manufactured using an assembly jig according to an embodiment. [Figure 5D] FIG. 2 is an illustration of an electrochemical cell stack manufactured using an assembly jig according to an embodiment. [Figure 6] 1A to 1C are illustrations of a method for incorporating a current collector according to an embodiment into an electrochemical cell. [Figure 7A] 1A to 1C are illustrations of a method for incorporating a current collector according to an embodiment into an electrochemical cell. [Figure 8A] FIG. 1 shows the capacity retention of electrochemical cells constructed and operated at various pressures. [Figure 8B] FIG. 1 shows the capacity retention of electrochemical cells constructed and operated at various pressures. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] The embodiments described herein relate to electrochemical cells and their manufacture. Some electrochemical cells described herein may include electrodes with multiple layers. Electrochemical cells with multi-layer electrodes are described in more detail in U.S. Patent Application Publication No. 2019 / 0363351 (the "'351 Publication"), filed May 24, 2019, entitled "High Energy-Density Composition-Gradient Electrodes and Methods of Making the Same," the disclosure of which is incorporated herein by reference in its entirety. Some multi-layer electrodes include a first layer including silicon and a second layer including graphite. For example, such electrodes may include a silicon-graphite interface. The silicon and graphite particles may contact each other. Air bubbles may form between the electrode layers, thereby preventing or at least partially inhibiting contact between the electrode layers. An SEI layer may form during the formation and initial cycles of the cell. These air bubbles and SEI layers may be at least partially mitigated by pressurizing the electrochemical cell and the layers of the electrodes during the formation of the electrochemical cell. In some embodiments, the pressure can be applied via an assembly fixture. By increasing the pressure during formation, there are fewer air bubbles and spaces for the SEI layer to form.

[0007] In some embodiments, the electrodes described herein can include conventional solid electrodes. In some embodiments, the solid electrodes can include a binder. In some embodiments, the electrodes described herein can include a semi-solid electrode. The semi-solid electrodes described herein can be made (i) thicker (e.g., greater than 100 μm, up to 2,000 μm, or more) due to the reduced tortuosity and increased electronic conductivity of the semi-solid electrodes, (ii) with higher loading of active materials, and (iii) with simplified manufacturing processes that utilize less equipment. These relatively thick semi-solid electrodes reduce the volume, mass, and cost contribution of inactive components to the active components, thereby increasing the commercial attractiveness of batteries made with semi-solid electrodes. In some embodiments, the semi-solid electrodes described herein are binder-free and / or do not use binders used in conventional battery manufacturing. Instead, the volume of the electrode that is normally occupied by binders in conventional electrodes is now occupied by: 1) the electrolyte. 2) an active material, which has the effect of increasing the charge capacity of the battery; or 3) a conductive additive, which has the effect of increasing the electronic conductivity of the electrode, which counters the high internal impedance of the thick conventional electrodes. The reduced tortuosity and increased electronic conductivity of the semi-solid electrodes described herein results in superior rate performance and charge capacity of electrochemical cells formed from the semi-solid electrodes. The semi-solid electrodes described herein can be made substantially thicker than conventional electrodes, allowing the ratio of active material (i.e., semi-solid cathode and / or anode) to inactive material (i.e., current collector and separator) to be much higher in batteries formed from electrochemical cell stacks including the semi-solid electrodes compared to similar batteries formed from electrochemical cell stacks including conventional electrodes. This results in a substantial increase in the overall charge capacity and energy density of batteries including the semi-solid electrodes described herein.

[0008] In some embodiments, the electrode materials described herein can be flowable semi-solid or condensed liquid compositions. In some embodiments, the electrode materials described herein can be binder-free or substantially binder-free. A flowable semi-solid electrode can include a suspension of electrochemically active material (anode or cathode particles or particulates) and, optionally, an electronically conductive material (e.g., carbon) in a non-aqueous liquid electrolyte. In other words, active electrode particles and conductive particles are co-suspended in the electrolyte to produce a semi-solid electrode. Examples of battery structures utilizing semi-solid suspensions are described in International Patent Publication No. WO2012 / 024499, entitled "Stationary, Fluid Redox Electrode," and International Patent Publication No. WO2012 / 088442, entitled "Semi-Solid Filled Battery and Method of Manufacture," the entire disclosures of which are incorporated herein by reference.

[0009] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, the term "member" is intended to mean a single member or a combination of members, and "material" is intended to mean one or more materials, or combinations thereof.

[0010] 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, etc. As an example, a portion of a support member described as being "substantially linear" is intended to convey that while linearity of the portion is desired, some non-linearity may occur in the "substantially linear" portion. Such non-linearity may result from manufacturing tolerances, or other practical considerations (e.g., pressure or force applied to the support member, etc.). Thus, a geometric structure modified by the term "substantially" includes such geometric characteristics within a tolerance of plus or minus 5% of the described geometric structure. For example, a "substantially linear" portion is one that defines an axis or centerline that is within plus or minus 5% of being linear.

[0011] As used herein, the terms "set" and "plurality" can refer to multiple features or a single feature with multiple portions. 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 separate electrodes. Furthermore, for example, when referring to multiple electrochemical cells, the multiple electrochemical cells can be considered as multiple separate electrochemical cells, or one electrochemical cell with multiple portions. Thus, a set of portions or multiple portions may include multiple portions that are continuous or discontinuous with each other. Multiple particles or multiple materials can also be made from multiple articles that are manufactured separately and then joined together (e.g., by mixing, adhesive, or any suitable method).

[0012] As used herein, the term "semi-solid" refers to a material that is a mixture of liquid and solid phases, such as, for example, a particle suspension, a slurry, a colloidal suspension, an emulsion, a gel, or a micelle.

[0013] As used herein, the terms "activated carbon network" and "networked carbon" refer to the general qualitative state of an electrode. For example, an electrode with an activated carbon network (or networked carbon) is such that the carbon particles in the electrode assume a particle morphology and arrangement that is separate from one another, facilitating electrical contact and electrical conductivity between the particles and through the thickness and length of the electrode. Conversely, the terms "non-activated carbon network" and "non-networked carbon" refer to an electrode in which the carbon particles exist as individual particle islands or multi-particle agglomerate islands that may not be sufficiently connected to provide adequate electrical conduction through the electrode.

[0014] As used herein, the terms "energy density" and "volumetric energy density" refer to the amount of energy (e.g., MJ) stored in an electrochemical cell per unit volume (e.g., L) of materials included to operate the electrochemical cell (such as electrodes, separators, electrolyte, and current collectors). Specifically, materials used to package the electrochemical cell are excluded from the volumetric energy density calculation.

[0015] As used herein, the term "high capacity material" or "high capacity anode material" refers to a material having an irreversible capacity greater than 300 mAh / g that can be incorporated into an electrode to facilitate the uptake of electroactive species. Examples include tin, tin alloys such as Sn-Fe, tin monoxide, silicon, silicon alloys such as Si-Co, silicon monoxide, aluminum, aluminum alloys, metal monoxides (CoO, FeO, etc.), or titanium oxide.

[0016] As used herein, the term "composite high capacity electrode layer" refers to an electrode layer having both high capacity materials and conventional anode materials, for example a silicon graphite layer.

[0017] As used herein, the term "solid high capacitance electrode layer" refers to an electrode layer having a single solid phase high capacitance material, for example, sputtered silicon, tin, tin alloys such as Sn-Fe, tin monoxide, silicon, silicon alloys such as Si-Co, silicon monoxide, aluminum, aluminum alloys, metal monoxides (CoO, FeO, etc.), or titanium oxide.

[0018] 1 is a block diagram of a method 10 of manufacturing an electrochemical cell according to an embodiment. As shown, the method 10 includes disposing a first cathode material on a cathode current collector (step 11). The method 10 optionally includes disposing a second cathode material on the first cathode material (step 12). The method 10 further includes disposing an anode material on the anode current collector (step 13), placing the anode and cathode in a cell assembly fixture and disposing a separator between the anode and cathode to form an electrochemical cell (step 14), and applying a pressure of at least about 3,500 kPa to the electrochemical cell (step 15). The method 10 optionally includes applying heat to the electrochemical cell (step 16).

[0019] Step 11 includes disposing a first cathode material on a cathode current collector to form a cathode. In some embodiments, the first cathode material can include a semi-solid cathode material. In some embodiments, the first cathode material can include a solid or conventional electrode material. In some embodiments, the first cathode material can include silicon. In some embodiments, the first cathode material can include graphite. In some embodiments, the first cathode material can include any of the electrode materials described in the '351 Publication.

[0020] Step 12 is optional and includes disposing a second cathode material on the first cathode material. In some embodiments, the second cathode material can include a semi-solid cathode material. In some embodiments, the second cathode material can include a solid or conventional electrode material. In some embodiments, the second cathode material can include silicon. In some embodiments, the second cathode material can include graphite. In some embodiments, the second cathode material can include any of the electrode materials described in the '351 Publication.

[0021] Step 13 includes disposing an anode material on an anode current collector to form an anode. In some embodiments, the anode material can include a semi-solid anode material. In some embodiments, the anode material can include a solid or conventional electrode material. In some embodiments, the anode material can include silicon. In some embodiments, the anode material can include graphite. In some embodiments, the anode material can include any of the electrode materials described in the '351 Publication.

[0022] Step 14 includes placing the anode and cathode in a cell assembly fixture and positioning a separator between the anode and cathode. In some embodiments, the separator can be placed between the anode and cathode before the anode and cathode are placed in the cell assembly fixture. In some embodiments, the separator can be placed between the anode and cathode after the anode and cathode are placed in the cell assembly fixture. In some embodiments, the anode, cathode, and separator can be placed in the cell assembly fixture with the anode on top. In some embodiments, the anode, cathode, and separator can be placed in the cell assembly fixture with the cathode on top.

[0023] Step 15 includes applying a pressure of at least about 3,500 kPa to the anode, cathode, and separator via the assembly fixture. In some embodiments, the applied pressure can be measured based on the pressure in the cathode. In some embodiments, the applied pressure can be measured based on the pressure in the anode. In some embodiments, the cell assembly fixture can include a spring to implement the pressure.

[0024] In some embodiments, the pressure applied by the cell assembly tool is at least about 3,500 kPa, at least about 4,000 kPa, at least about 4,500 kPa, at least about 5,000 kPa, at least about 5,500 kPa, at least about 6,000 kPa, at least about 6,500 kPa, at least about 7,000 kPa, at least about 7,500 kPa, at least about 8,000 kPa, at least about 8,500 kPa, at least about It can be at least about 9,000 kPa, at least about 9,500 kPa, at least about 10,000 kPa, at least about 10,500 kPa, at least about 11,000 kPa, at least about 11,500 kPa, at least about 12,000 kPa, at least about 12,500 kPa, at least about 13,000 kPa, at least about 13,500 kPa, at least about 14,000 kPa, or at least about 14,500 kPa. In some embodiments, the pressure applied by the cell assembly fixture is about 15,000 kPa or less, about 14,500 kPa or less, about 14,000 kPa or less, about 13,500 kPa or less, about 13,000 kPa or less, about 12,500 kPa or less, about 12,000 kPa or less, about 11,500 kPa or less, about 11,000 kPa or less, about 10,500 kPa or less, about 10 The pressure can be about 3,500 kPa or less, about 15,000 kPa or less, about 9,500 kPa or less, about 9,000 kPa or less, about 8,500 kPa or less, about 8,000 kPa or less, about 7,500 kPa or less, about 7,000 kPa or less, about 6,500 kPa or less, about 6,000 kPa or less, about 5,500 kPa or less, about 5,000 kPa or less, about 4,500 kPa or less, or about 4,000 kPa or less. Combinations of the foregoing pressures are also possible (e.g., at least about 3,500 kPa and about 15,000 kPa or less, or at least about 5,000 kPa and about 10,000 kPa or less), including all values ​​and ranges therebetween.In some embodiments, the pressure applied by the cell assembly fixture can be about 3,500 kPa, about 4,000 kPa, about 4,500 kPa, about 5,000 kPa, about 5,500 kPa, about 6,000 kPa, about 6,500 kPa, about 7,000 kPa, about 7,500 kPa, about 8,000 kPa, about 8,500 kPa, about 9,000 kPa, about 9,500 kPa, about 10,000 kPa, about 10,500 kPa, about 11,000 kPa, about 11,500 kPa, about 12,000 kPa, about 12,500 kPa, about 13,000 kPa, about 13,500 kPa, about 14,000 kPa, about 14,500 kPa, or about 15,000 kPa.

[0025] In some embodiments, the cell assembly fixture is capable of applying a force of at least about 100 N, at least about 200 N, at least about 300 N, at least about 400 N, at least about 500 N, at least about 600 N, at least about 700 N, at least about 800 N, at least about 900 N, at least about 1,000 N, at least about 1,100 N, at least about 1,200 N, at least about 1,300 N, at least about 1,400 N, at least about 1,500 N, at least about 1,600 N, at least about 1,700 N, at least about 1,800 N, at least about 1,900 N, at least about 2,000 N, at least about 2,100 N, at least about 2,200 N, at least about 2,300 N, or at least about 2,400 N. In some embodiments, the cell assembly fixture can apply a force of about 2,500 N or less, about 2,400 N or less, about 2,300 N or less, about 2,200 N or less, about 2,100 N or less, about 2,000 N or less, about 1,900 N or less, about 1,800 N or less, about 1,700 N or less, about 1,600 N or less, about 1,500 N or less, about 1,400 N or less, about 1,300 N or less, about 1,200 N or less, about 1,100 N or less, about 1,000 N or less, about 900 N or less, about 800 N or less, about 700 N or less, about 600 N or less, about 500 N or less, about 400 N or less, about 300 N or less, or about 200 N or less.

[0026] Combinations of the foregoing forces are also possible (eg, at least about 100 N and up to about 2,500 N, or at least about 500 N and up to about 1,500 N), including all values ​​and ranges therebetween. In some embodiments, the cell assembly fixture can apply a force of about 100N, about 200N, about 300N, about 400N, about 500N, about 600N, about 700N, about 800N, about 900N, about 1,000N, about 1,100N, about 1,200N, about 1,300N, about 1,400N, about 1,500N, about 1,600N, about 1,700N, about 1,800N, about 1,900N, about 2,000N, about 2,100N, about 2,200N, about 2,300N, about 2,400N, or about 2,500N. In some embodiments, the force can be applied vertically. In some embodiments, the force can be applied horizontally. In some embodiments, the force can be applied at an angle relative to the vertical (e.g., about 10°, about 20°, about 30°, about 40°, about 45°, about 50°, about 60°, about 70°, or about 80°, including all values ​​and ranges therebetween). In other words, the fixture can be rotated relative to the vertical as a force is applied to the electrochemical cell.

[0027] Step 16 is optional and includes applying heat to the electrochemical cell. In some embodiments, applying heat can aid in the release of gases during pressurization. In some embodiments, the heat applied is sufficient to evaporate binders that have migrated to the interface between the first cathode material and the cathode current collector. In some embodiments, the heat applied is sufficient to evaporate binders that have migrated to the interface between the anode material and the anode current collector. In some embodiments, the heat applied is sufficient to evaporate binders that have migrated to the interface between the first cathode material and the second cathode material. In some embodiments, the heat can be applied via a neodymium doped yttrium aluminum garnet (Nd:YAG) laser, a CO2 laser, electron beam irradiation, plasma, corona, deep ultraviolet (UV), etching, infrared, hot plate, hot rolling, steam treatment, sputtering, Cu / C sputtering, and / or direct combustion. In some embodiments, the electrochemical cell can be heated to a temperature of at least about 30°C, at least about 35°C, at least about 40°C, at least about 45°C, at least about 50°C, at least about 55°C, at least about 60°C, at least about 65°C, at least about 70°C, at least about 75°C, at least about 80°C, at least about 85°C, at least about 90°C, at least about 95°C, at least about 100°C, at least about 105°C, at least about 110°C, at least about 115°C, at least about 120°C, at least about 125°C, at least about 130°C, at least about 135°C, at least about 140°C, at least about 145°C, or at least about 150°C.

[0028] 2 is a block diagram of an assembly fixture 200 for assembling an electrochemical cell according to an embodiment. As shown, the assembly fixture 200 includes a top plate 210, a middle plate 220, and a bottom plate 230, with a spring 225 disposed between the top plate 210 and the middle plate 220. The top plate 210 is coupled to the bottom plate 230. The top plate 210 is also coupled to the spring 225. The middle plate 220 is coupled to the spring 225. In some embodiments, the top plate 210 can be coupled to the middle plate 220. In some embodiments, the middle plate 220 can be coupled to the bottom plate 230.

[0029] In some embodiments, the top plate 210, the middle plate 220, and / or the bottom plate 230 can be made of metal, ceramic, wood, plastic, polymer, polyethylene, polypropylene, or any other suitable material, or combinations thereof. In some embodiments, the top plate 210 can include a groove or recess for the spring 225 to rest against. In some embodiments, the middle plate 220 can be fastened to the top plate 210 via fasteners (e.g., screws, bolts, anchors, nuts, nails, rivets, or any combination thereof). In some embodiments, the middle plate 220 can be fastened to the bottom plate 230 via fasteners. In some embodiments, the fasteners that connect the top plate 210 to the middle plate 220 can be the same fasteners that connect the middle plate 220 to the bottom plate 230. In some embodiments, the fasteners can connect the top plate 210 to the bottom plate 230 directly and can be positioned through non-threaded holes in the middle plate 220.

[0030] The springs 225 provide the force that presses the electrochemical cell between the middle plate 220 and the bottom plate 230. The tightness of the fasteners can be adjusted to vary the force applied to the cell. For example, tightening each of the fasteners a quarter turn can increase the pressure in the electrochemical cell by approximately 50-100 kPa. The bottom plate 230 provides support for the electrochemical cell when it is placed between the bottom plate 230 and the middle plate 220. In some embodiments, each of the fasteners can be tightened simultaneously. In some embodiments, the fasteners can be tightened at alternating intervals (e.g., tightening a first fastener, then tightening a second fastener, etc.).

[0031] 3A-3D are illustrations of an assembly jig 300 for manufacturing an electrochemical cell EC according to an embodiment. As shown, the assembly jig 300 includes an upper plate 310, a middle plate 320, and a lower plate 330, with a spring 325 disposed between the upper plate 310 and the middle plate 320. In some embodiments, the upper plate 310, the middle plate 320, the spring 325, and the lower plate 330 can be the same as or substantially similar to the upper plate 210, the middle plate 220, the spring 225, and the lower plate 230 described above with reference to FIG. 2. Accordingly, certain aspects of the upper plate 310, the middle plate 320, the spring 325, and the lower plate 330 will not be described in greater detail herein. FIG. 3A shows an auxiliary view of the assembly jig 300 with parts separated to show details. FIG. 3B shows an auxiliary view of the assembly jig 300 with parts assembled. 3C shows a cross-sectional view of assembly fixture 300 to reveal details of spring 325. FIG. 3D is a diagram of electrochemical cell EC within assembly fixture 300.

[0032] The assembly jig 300 includes fasteners 312 for coupling the top plate 310 to the bottom plate 330 and / or the middle plate 320. The fasteners 312 can be tightened or loosened to induce a desired pressure in the electrochemical cell EC. Washers 314 can be placed between the fasteners 312 and the top plate 310 to protect the top plate 310 and distribute the applied load when the fasteners 312 are tightened. As shown, the assembly jig 300 includes four fasteners 312. In some embodiments, the assembly jig 300 can include 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or at least about 20 fasteners 312, including all values ​​and ranges therebetween. As shown, a first set of fasteners 312 are threaded through the top plate 310 and fastened to threads in the bottom plate 330. The fasteners 312 are shown passing through the middle plate 320 without being threaded within the middle plate 320. In some embodiments, the fasteners 312 can be threaded into the middle plate 320.

[0033] As shown, the top plate 310 includes recesses 316 for positioning the springs 325. In some embodiments, the top plate 310 can be bonded to the springs 325 (e.g., via welding and / or adhesive). The middle plate 320 is not threaded as shown. In other words, the threads of the fasteners pass through the middle plate 320 without being fastened directly to it. As shown, the middle plate 320 includes recesses 326 for positioning the springs 325. In some embodiments, the middle plate 320 can be bonded to the springs 325 (e.g., via welding and / or adhesive). As shown, the assembly jig 300 includes eight springs 325. In some embodiments, the assembly jig 300 can include 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, or at least about 40 springs 325, including all values ​​and ranges therebetween.

[0034] 3D illustrates an electrochemical cell EC between the middle plate 320 and the bottom plate 330. As shown, the electrochemical cell EC includes an anode current collector ACC having a first anode material AM1 and a cathode current collector CCC having a cathode material CM disposed thereon. A second anode material AM2 is disposed on the first anode material AM1, and a separator S is disposed between the cathode material CM and the second anode material AM2. As shown, the anode includes multiple layers. In some embodiments, the cathode can include multiple layers. In some embodiments, the anode and cathode can include multiple layers. In some embodiments, neither the anode nor the cathode can include multiple layers. An initial cycle of the electrochemical cell EC can be performed with the electrochemical cell EC placed in a fixture and subjected to a desired pressure. In some embodiments, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or at least about 20 initial cycles can be performed while the electrochemical cell EC is under the desired pressure, including all values ​​and ranges therebetween. As shown, the spring 325 is above the electrochemical cell EC. In some embodiments, the spring 325 can be positioned below the electrochemical cell EC and push upward. As shown, a single electrochemical cell EC is placed in the assembly fixture 300. In some embodiments, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or at least about 20 electrochemical cells can be stacked together in the assembly fixture 300.

[0035] 4 is an illustration of an assembly fixture 400 for manufacturing an electrochemical cell stack ECS (or a single electrochemical cell) according to an embodiment. As shown, the assembly fixture 400 includes a top plate 410, a middle plate 420, and a bottom plate 430, with fasteners 412 securing the plates together. In some embodiments, the top plate 410, the fasteners 412, the middle plate 420, and the bottom plate 430 can be the same as or substantially similar to the top plate 310, the fasteners 312, the middle plate 320, and the bottom plate 330 described above with reference to FIGS. 3A-3D. Accordingly, certain aspects of the top plate 410, the fasteners 412, the middle plate 420, and the bottom plate 430 will not be described in greater detail herein.

[0036] A hydraulic ram 435 is disposed between the middle plate 420 and the bottom plate 430 and provides pressure to the electrochemical cell stack ECS by pushing the middle plate 420 upward. A pneumatic multiplier 437 is fluidly coupled to the hydraulic ram 435. In some embodiments, the pneumatic multiplier 437 can include a hydraulic pump. In some embodiments, the pneumatic multiplier 437 can be operated manually (i.e., by hand). In some embodiments, the pneumatic multiplier 437 can be operated by electricity, gas power, or any other suitable power generation method. In some embodiments, the pneumatic multiplier 437 can be automated. In some embodiments, the pneumatic multiplier 437 can be operated by a computer. As shown, the hydraulic ram 435 and the pneumatic multiplier 437 are disposed below the middle plate 420 and push upward to apply force to the electrochemical cell stack ECS. In some embodiments, the hydraulic ram 435 and pneumatic hydraulic multiplier 437 are positioned above the middle plate 420 and can push downward to apply force to the electrochemical cell stack ECS with the electrochemical cell stack ECS positioned between the middle plate 420 and the bottom plate 430.

[0037] 5A-5D are illustrations of electrochemical cell stacks fabricated using an assembly tool according to an embodiment. FIG. 5A shows a single electrochemical cell EC1, and FIG. 5B shows multiple electrochemical cells EC1, EC2, EC3, EC4 stacked together to form an electrochemical cell stack ECS. FIG. 5C shows an apparatus 500 including an electrochemical cell stack ECS inside a case 542 with a cover 544 positioned over the case 542 (exploded view). FIG. 5D shows the apparatus 500 in its completed form.

[0038] 5A and 5B, each of the electrochemical cells EC1, EC2, EC3, and EC4 (collectively referred to as electrochemical cells EC) includes an anode material AM1, AM2, AM3, and AM4 (collectively referred to as anode material AM), an anode current collector ACC1, ACC2, ACC3, and ACC4 (collectively referred to as anode current collector ACC), a cathode material CM1, CM2, CM3, and CM4 (collectively referred to as cathode material CM), a cathode current collector CCC1, CCC2, CCC3, and CCC4 (collectively referred to as cathode current collector CCC), a separator S1, S2, S3, and S4 (collectively referred to as separator S), and a film F1, F2, F3, and F4 (collectively referred to as film F). As shown, film F forms a partial pouch but does not completely cover anode current collector ACC or cathode current collector CCC. Cathode current collector CCC1 is in physical contact with anode current collector ACC2, cathode current collector CCC2 is in physical contact with anode current collector ACC3, and so on. As shown, the electrochemical cells ECC are arranged in series. In some embodiments, the voltage measured from anode current collector ACC1 to anode current collector ACC3 can be about twice the voltage measured from anode current collector ACC1 to anode current collector ACC2. As an example, the voltage measured from anode current collector ACC1 to anode current collector ACC2 can be about 3.6V, the voltage measured from anode current collector ACC1 to anode current collector ACC3 can be about 7.2V, the voltage measured from anode current collector ACC1 to anode current collector ACC4 can be about 10.8V, and the voltage measured from anode current collector ACC1 to cathode current collector CCC4 can be about 14.4V. In some embodiments, the electrochemical cell stacks ECS can be arranged in parallel. As shown, the electrochemical cell stack ECS includes four electrochemical cells EC. In some embodiments, the electrochemical cell stack ECS can include 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or at least about 20 electrochemical cells EC. In some embodiments, each of the electrochemical cells EC can have the same battery chemistry.In some embodiments, the electrochemical cells EC can have a variety of battery chemistries.

[0039] Applying high pressure during the fabrication of the electrochemical cell stack ECS can be highly beneficial to the performance. Applying pressure during the fabrication of the electrochemical cell stack ECS can improve the contact between adjacent anode and cathode current collectors (e.g., anode current collector ACC2 and cathode current collector CCC1) and can remove air bubbles from the anode material AM and / or cathode material CM. This can improve the capacity retention and efficiency of the electrochemical cell EC.

[0040] FIGURE 5C shows the electrochemical cell stack ECS loaded into the case 542 with the cover in place. As shown, the case 542 includes a voltage monitor 546 integrated therein. In some embodiments, the voltage monitor 546 can monitor the voltage drop across each of the electrochemical cells EC. FIGURE 5D shows the device 500 in its assembled form, with the electrochemical cell stack ECS inside the case 542.

[0041] 6A-6C illustrate a method for incorporating an EC current collector according to an embodiment into an electrochemical cell. The electrochemical cell EC can be similar and / or the same as an electrochemical cell included in an electrochemical stack disclosed herein (e.g., electrochemical cell EC1, EC2, EC3, or EC4). The current collector can be an anode current collector or a cathode current collector. FIG. 6A illustrates that an example anode current collector foil ACC can be attached and / or bonded to a film F via a pre-lamination step. The pre-lamination step can be any suitable lamination procedure in which a first material (e.g., anode current collector foil ACC) is placed adjacent and in contact with a second material (e.g., film F) and heat and / or pressure is applied to facilitate and / or promote adhesion and lamination bond formation at the interface of the two materials. FIG. 6A shows that the pre-lamination step can introduce a strong (e.g., permanent) lamination bond (SB) onto selected areas of the anode current collector ACC in contact with the film F, while leaving exposed surfaces S1 and S2 on each side of the anode current collector ACC. The anode current collector ACC pre-laminated to the film F can be placed onto a shaped casting pallet 648 that includes protrusions shaped and sized to match the dimensions of the exposed surfaces S2. FIG. 6B shows that an anode electrode material (AM) can then be cast onto the anode current collector ACC. Alternatively and / or optionally, in some embodiments, two or more anode materials (AM) can be cast onto the anode current collector ACC (e.g., a first anode material AM1 can be cast onto the anode current collector ACC, and then a second anode material AM2 can be cast onto the first anode material AM1). FIG. 6C shows that the anode current collector ACC with the cast anode material AM can then be removed from the molded casting pallet 648 to produce an electrode with a consistent electrode coating thickness and an open surface S2 that can be used to make electrical connections when multiple electrochemical cells are stacked.

[0042] 7A-7C illustrate a method for incorporating a current collector into an electrochemical cell EC according to another embodiment. Similar to the method described in FIGS. 6A-6C, the electrochemical cell EC can be any suitable electrochemical cell (e.g., electrochemical cells EC1, EC2, EC3, or EC4) included in an electrochemical stack, and the current collector can be either an anode current collector or a cathode current collector. FIG. 7A shows an example anode current collector foil ACC attached and / or bonded to a film F in a pre-lamination step. During the pre-lamination step, the anode current collector ACC is attached to the film F by forming and / or creating two different types of contact areas and / or joints between the two materials. In the first type of contact area, the anode current collector ACC is laminated to the film F to form a strong bond (SB). The strong bond (SB) is intended to form a permanent bond between the anode current collector ACC and the film F. In the second type of contact area, the anode current collector ACC is laminated to the film F to form a weak bond (WB). The weak bond (WB) is intended to form a temporary bond (e.g., a removable bond) between the anode current collector ACC and the film F. A small perforation or gap separates the contact area with a permanent bond from the contact area with a temporary bond. FIG. 7B shows that the anode current collector ACC pre-laminated to the film F can be placed in a flat casting pallet 748. An anode electrode material (AM) can then be cast onto the anode current collector ACC. Alternatively and / or optionally, in some embodiments, two or more anode materials (AM) can be cast onto the anode current collector ACC (e.g., a first anode material AM1 can be cast onto the anode current collector ACC, and then a second anode material AM2 can be cast onto the first anode material AM1). After casting, the portion of film F that is attached to the current collector via the weak bond (WB) may be removed to expose the current collector surface.FIG. 7C shows that the anode current collector ACC with the cast anode material AM can then be removed from the molded casting pallet 648 to form an electrode with a consistent electrode coating thickness and an open surface S2 that can be used to make electrical connections when stacking multiple electrochemical cells.

[0043] 8A-8B show the capacity retention of electrochemical cells constructed and operated at various pressures. Each of the cells was constructed with a cathode layer comprising 50 vol.% Lithium Nickel Manganese Cobalt Oxide (NMC) and 2 vol.% Ketjen. The cells were divided into four groups based on the cell construction process. Each of the cells in "Group 1", "Group 2", "Group 3", and "Group 4" comprises an anode with one layer of silicon and a second anode layer with a 58 vol.% mixture of graphite and C45 carbon black (C45). The cells in Group 1 have an anode with one layer of thin-film sputtered silicon and a second anode layer with a 58 vol.% mixture of graphite and C45. The cells in Group 2 have an anode with one layer of thin-film sputtered silicon and a second anode layer with a 58 vol.% mixture of graphite and C45. After assembling the separator onto the second anode layer and the cathode layer, the cells in group 2 are densified by a pressure of about 25,000 kPa. The cells in group 3 have an anode comprising one layer of thin film sputtered silicon and a second anode layer with a 58% by volume mixture of graphite and C45. After assembling the separator onto the second anode layer and the cathode layer, the assembly in group 3 is heat treated for up to about 10 hours. The cells in group 4 have an anode comprising one layer of a wet coated blend of silicon, SBR / CMC based binder, and carbon additive and a second anode layer with a 58% by volume mixture of graphite and C45.

[0044] FIG. 8A shows the area specific impedance (ASI) increase and capacity retention during cycling, expressed as a percentage relative to the first C / 3 cycle. Cells formed at 1,379 kPa and cycled at 1,379 kPa are shown as circles. Cells formed at 1,379 kPa and cycled at 96.5 kPa are shown as squares. Cells formed at 3,447 kPa and cycled at 96.5 kPa are shown as plus signs. Cells formed at 10,342 kPa and cycled at 96.5 kPa are shown as "x" signs. As shown in FIG. 8A, the general trend is higher ASI increase for cells cycled at 96.5 kPa, but the rate of ASI increase decreases as the formation pressure increases. The general trend shows that increasing the formation pressure to 3,447 kPa and 10,342 kPa increases the capacity retention compared to the first C / 3 cycle.

[0045] FIG. 8B shows the C / 3 capacity retention relative to the initial C / 10 cycle, expressed as a percentage of the C / 10 capacity. The capacity fade is reduced for cells with higher formation pressures, improving the rate capability of the cells. The capacity fade is reduced for cells with higher formation pressures, improving the rate capability of the cells. In FIG. 8B, the cell formed and cycled at 1,379 kPa shows about 82% retention compared to the C / 10 cycle. In comparison, the cells with cycle pressures of 96.5 kPa and formation pressures of 1,379 kPa, 3,447 kPa, and 10,342 kPa show 90%, 88%, and 86% capacity retention, respectively, compared to the C / 10 cycle. Without wishing to be bound by any particular theory, a mechanism for this trend may be that the lower pressure cycles enable better rate capability of the silicon anode layer. Increasing the forming pressure helps improve the internal resistance by improving the contact resistance between the silicon anode layer and the graphite anode layer, but with some loss of capacity as a result of high compression of the graphite layers.

[0046] Table 1 shows a comparison of the specific power during a 30 second 1C pulse and the internal resistance (IR) during the pulse. In each of Groups 2, 3, and 4, the cells formed at higher pressures generally have a lower IR. This lower IR helps improve the rate performance, i.e., the trend of capacity retention versus cycle rate. Each of the cells was formed with an NMC811 cathode (60% solids loading by volume) and a graphite anode with a carbon additive and 73.4% solids loading by volume. [Table 1]

[0047] During charging of the electrochemical cell, the silicon anode layer alloys with lithium to form lithiated silicon (Li x Si). When the lithium concentration in the lithiated silicon alloy increases, the volume of the alloy can expand by up to about 300%. Due to this large volume expansion of the silicon anode layer during charging, when the lithium concentration in the lithiated silicon alloy decreases during discharge, contact separation between the graphite anode layer and the silicon anode layer can occur. In other dual anode systems where both the graphite anode layer and the silicon anode layer contain adhesive polymer binders, this contact separation is not as critical an issue as it is with semi-solid graphite. This significant contact separation with semi-solid graphite can lead to the continuous deposition of SEI products at the interface between the silicon anode layer and the graphite anode layer during cycling, leading to high ASI growth rates and high internal resistance of the electrochemical cell.

[0048] High pressure cycling of the dual anode layer may reduce the contact separation between the graphite and silicon anode layers, reducing the rate of ASI increase. This high pressure limits the lithium concentration in the lithiated silicon alloy, and therefore the degree of contact separation during discharge. The drawbacks of high pressure cycling are not only limited to the reduction in capacity of the silicon at higher cycle rates, but also the increased weight, volume, and cost of the packaging required for the cell to sustain such pressures.

[0049] High pressure formation with low pressure cycles for dual anodes including semi-solid graphite anode layer and silicon anode layer allows for reduced ASI increase and improved capacity retention at low pressure cycles compared to high pressure cycles. This improved ASI increase rate at higher formation pressure can be attributed, at least in part, to improved interfacial contact during formation and improved mechanical integrity of the SEI at the interface between the silicon anode layer and the graphite anode layer, which leads to improved electrochemical SEI passivation at the interface. The improved rate performance can also be attributed to lower internal resistance of the cell. High pressure imposed on the semi-solid graphite anode layer reduces the cell internal resistance by improving the contact area through rearrangement of the semi-solid particle suspension of the graphite anode layer at the interface between the graphite anode layer and the silicon anode layer. This improved contact area removes voids and / or bubbles at the interface between the semi-solid graphite anode layer and the silicon anode layer. This improved contact area significantly reduces the SEI formed at the interface and the increase in internal resistance between the graphite and silicon anode layers by preventing excessive SEI formation in areas where gas bubbles and voids exist.

[0050] Various concepts may be embodied as one or more methods, at least one example of which is provided. Acts performed as part of the methods may be ordered in any suitable manner. Thus, embodiments may be constructed in which operations are performed in an order different from that illustrated, including performing some operations simultaneously, although shown as sequential operations in the exemplary embodiment. In other words, such features are not necessarily limited to a particular order of execution, but rather, it should be understood that any number of processing flows, processes, services, servers, and / or the like may be performed sequentially, asynchronously, simultaneously, in parallel, simultaneously, synchronously, and / or the like, in a manner consistent with the present disclosure. Thus, some of these features may be mutually incompatible in that they cannot exist simultaneously in a single embodiment. Similarly, some features are applicable to some aspects of the invention and not to other aspects.

[0051] Furthermore, the present disclosure may include other inventions not currently described. The applicants retain all rights in such inventions, including the right to practice such inventions and to file additional applications, continuations, continuations-in-part, divisional applications, and / or the like. As such, it should be understood that the advantages, embodiments, examples, functions, features, logical, operational, organizational, structural, topological, and / or other aspects of the present disclosure should not be considered as limitations of the present disclosure defined by the embodiments or limitations of equivalents of the embodiments. Depending on the particular desires and / or characteristics of individual and / or business users, database configurations and / or relational models, data types, data transmission and / or network frameworks, syntax structures, etc., various embodiments of the technology disclosed herein may be implemented in a manner that allows for great flexibility and customization, as described herein.

[0052] All definitions, as defined and used herein, should be understood to supersede any dictionary definitions, definitions in documents incorporated by reference, and / or ordinary meaning of the defined terms.

[0053] As used herein, in certain embodiments, the term "about" or "approximately" when preceding a numerical value indicates a range of the value plus or minus 10%. When a range of values ​​is provided, it is understood that each intervening value between the upper and lower limits of that range, to the tenth of the unit of the lower limit, and any other stated or intervening value within that stated range, is encompassed within the disclosure unless the context clearly dictates otherwise. The upper and lower limits of these smaller ranges are independently encompassed within the disclosure, subject to any specifically excluded limit in the stated range, which may be included in the smaller range. When a stated range includes one or both of the limits, ranges excluding one or both of those included limits are also included in the disclosure.

[0054] As used herein and in embodiments, the term "and / or" should be understood to mean "either or both" of the elements so conjoined, i.e., elements that are conjunctive in some cases and disjunctive in other cases. Multiple elements listed with "and / or" should be interpreted in the same manner, i.e., "one or more" of the elements so conjoined. Other elements other than the elements specifically identified by the "and / or" clause may optionally be present, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to "A and / or B," when used in conjunction with open-ended language such as "comprising," may refer in one embodiment to only A (optionally including elements other than B), in another embodiment to only B (optionally including elements other than A), in yet another embodiment to both A and B (optionally including other elements), etc.

[0055] As used herein and in the embodiments, "or" should be understood to have the same meaning as "and / or" as defined above. For example, when separating items in a list, "or" or "and / or" shall be interpreted as inclusive, i.e., including at least one of a number or list of elements, but more than one, and, optionally, including additional unlisted items. Only terms clearly indicated to the contrary, such as "only one of" or "exactly one of," or, when used in the embodiments, "consisting of," will refer to the inclusion of exactly one element of a number or list of elements. In general, when used herein, the term "or" shall be interpreted as indicating exclusive alternatives (i.e., "one or the other, but not both") only when preceded by a term of exclusivity, e.g., "either," "one of," "only one of," or "exactly one of." "Consisting essentially of," when used in the embodiments, shall have its ordinary meaning as used in the field of patent law.

[0056] As used herein and in embodiments herein, the phrase "at least one" should be understood in reference to a list of one or more elements to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each element specifically listed in the list of elements, and not excluding any combination of elements in the list of elements. This definition also allows for elements other than those specifically identified in the list of elements to which the phrase "at least one" refers, whether or not related to the specifically identified elements, may optionally be present. Thus, as a non-limiting example, "at least one of A and B" (or, equivalently, "at least one of A or B" or, equivalently, "at least one of A and / or B") can refer to, in one embodiment, at least one, and optionally more than one, A, and no B (and optionally including elements other than B); in another embodiment, at least one, and optionally more than one, B, and no A (and optionally including elements other than A); in yet another embodiment, at least one, and optionally more than one, A, and at least one, and optionally more than one, B (and optionally including other elements), etc.

[0057] In the embodiments, as well as in the above specification, all transitional phrases such as "comprising," "including," "carrying," "having," "containing," "involving," "holding," "consisting of," and the like, are to be understood to be open ended, i.e., to mean "including, but not limited to." Only the transitional phrases "consisting of" and "consisting essentially of" shall be closed or semi-closed transitional phrases, respectively, as set forth in Section 2111.03 of the United States Patent Office Manual of Patent Examining Procedures.

[0058] Although certain embodiments of the present disclosure have been outlined above, many alternatives, modifications, and variations will be apparent to those skilled in the art. Thus, the embodiments described herein are intended to be illustrative, rather than limiting. Various changes may be made without departing from the spirit and scope of the present disclosure. Where the methods and steps described above show certain events occurring in a certain order, those skilled in the art having the benefit of this disclosure will recognize that the order of certain steps may be changed, and such changes are in accordance with the variations of the present invention. Furthermore, some steps may be performed simultaneously, where possible, in parallel processing, rather than only sequentially as described above. Although embodiments have been shown and described in detail, it will be understood that various changes in form and details may be made.

Claims

1. 1. A method comprising: disposing a cathode material on a cathode current collector to form a cathode; disposing an anode material on an anode current collector to form an anode; placing the anode and the cathode in an assembly fixture and positioning a separator between the anode and the cathode to form an electrochemical cell, the assembly fixture applying a force to the electrochemical cell such that a pressure within the cathode material is at least about 3,500 kPa; The method includes:

2. The anode material is a first anode material, and the method further comprises: The method of claim 1 comprising disposing a second anode material over the first anode material.

3. The method of claim 2 , wherein the first anode material comprises silicon.

4. The method of claim 3 , wherein the second anode material comprises graphite.

5. The method of claim 1 , wherein the assembly fixture applies a force to the electrochemical cell such that a pressure within the cathode material is at least about 7,000 kPa.

6. The method of claim 5 , wherein the assembly fixture applies a force to the electrochemical cell such that a pressure within the cathode material is at least about 8,000 kPa.

7. 13. The method of claim 1, further comprising applying heat to the electrochemical cell in an amount sufficient to evaporate binder that has migrated to at least one of an interface between the cathode material and the cathode current collector or an interface between the anode material and the anode current collector.

8. 3. The method of claim 2, further comprising applying heat to the electrochemical cell in an amount sufficient to evaporate binder that has migrated to an interface between the first and second cathode materials.

9. The heat is generated by a Nd:YAG laser, CO ２ 10. The method of claim 8, wherein the coating is applied via at least one of laser, e-beam irradiation, plasma, corona, deep UV, etching, infrared, hot plate, hot rolling, steam treatment, sputtering, Cu / C sputtering, or direct combustion.

10. The method of claim 1 , wherein the assembly fixture applies the force via a pneumatic hydraulic multiplier and a hydraulic ram.

11. 1. A method comprising: placing the anode, the cathode, and a separator in contact with a first plate of an assembly fixture such that at least one of the anode or the cathode is in contact with the first plate; placing a second plate in contact with at least one of the anode and the cathode; placing a plurality of springs in contact with the second plate; fastening a third plate to the first plate such that the third plate contacts the plurality of springs and the plurality of springs press against the second plate, such that the second plate presses against the anode, the cathode, and the separator with a force such that a pressure within the cathode is at least about 3,500 kPa; The method includes:

12. The method of claim 11 , wherein the anode comprises a first anode material and a second anode material.

13. The method of claim 11 , wherein the first plate is positioned below the second plate, and the second plate is positioned below the third plate.

14. The method of claim 11 , wherein the second plate and the third plate each include a recess, and the plurality of springs fit within the plurality of recesses.

15. 12. The method of claim 11, further comprising applying heat to the anode and the cathode in an amount sufficient to evaporate binder that has migrated to an interface between an electrode material of the anode and the cathode and a current collector.

16. The heat is generated by a Nd:YAG laser, CO ２ 16. The method of claim 15, wherein the coating is applied via at least one of laser, electron beam irradiation, plasma, corona, deep UV, etching, infrared, hot plate, hot rolling, steam treatment, sputtering, Cu / C sputtering, or direct combustion.

17. The method of claim 11 , wherein said fastening creates a pressure within said cathode of at least about 7,000 kPa.

18. 1. An assembly tool for assembling an electrochemical cell, comprising: a first plate configured to contact at least one of the anode or the cathode; a second plate configured to contact at least one of the anode or the cathode; A third plate; a plurality of fasteners connecting the third plate to the first plate; a force member between the second plate and the third plate, the force member configured to apply a force on the second plate and the anode, the cathode, and a separator disposed between the anode and the cathode.

19. The assembly fixture of claim 18 , wherein the force members include a plurality of springs.

20. 20. The assembly fixture of claim 19, wherein the second plate and the third plate each include a plurality of recesses, and the plurality of springs fit within the plurality of recesses.

21. 20. The assembly fixture of claim 18, wherein the second plate is positioned above the first plate and the third plate is positioned above the second plate.

22. 19. The assembly fixture of claim 18, wherein the second plate is located below the first plate and the third plate is located below the second plate, and the force member includes a pneumatic hydraulic multiplier and a hydraulic ram located between the third plate and the second plate, the pneumatic hydraulic multiplier and the hydraulic ram configured to provide an upward force on the second plate.

23. 20. The assembly fixture of claim 18, wherein the plurality of fasteners are threaded into the first plate and the third plate, and the plurality of fasteners pass through unthreaded holes in the second plate.

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