Systems, devices, and methods for providing heat to electrochemical cells and electrochemical cell stacks

Abstract

[0003] Embodiments described herein include electrochemical cells having a heating element integrated therein. In some aspects, the electrochemical cell includes an anode current collector, an anode material disposed on the anode current collector, a cathode current collector, a cathode material disposed on a first side of the cathode current collector, a separator disposed between the anode material and the cathode material, and a heating element disposed on a second side of the cathode current collector opposite the first side. The heating element may include an electrically conductive material and a conductive material and may be disposed within an insulating material.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63 / 394,341, filed August 2, 2022, entitled "Electrochemical Cells and Electrochemical Cell Stacks with Series Connections and Methods of Producing, Operating, and Monitoring the Same," the disclosure of which is incorporated herein by reference in its entirety.

[0002] SUMMARY OF THE INVENTION The embodiments described herein relate to electrochemical cells and electrochemical cell stacks that include heating elements, and methods for operating and monitoring the same. [Background technology]

[0003] Lithium-ion batteries have demonstrated difficulties in charging at low temperatures. In fact, charging lithium-ion batteries at certain low temperatures can become unsafe. The temperature at which charging a cell becomes unsafe depends on the cell's chemistry and material design. When a lithium-ion battery is charged in a low-temperature environment, ions in the electrolyte are deposited in metallic form on the surface of the active material due to a decrease in the active material's ability to absorb ions. Lithium metal is highly reactive, increasing the risk of ion deposition on the surface of the active lithium material each time a charging current flows through the cell. Over time, lithium metal forms dendrites (e.g., metal pillars) that can grow into and through the separator, potentially causing the cell to experience thermal runaway, even when the cell is at low temperature and low state of charge (SOC). Electrochemical cells have traditionally been heated via water or pads to distribute heat throughout the cell or cell stack. However, this method increases system costs and adds extraneous steps to the process, thereby increasing assembly complexity. Therefore, an alternative solution for heating electrochemical cells that can enable cell charging at low temperatures is needed. Summary of the Invention

[0004]

[0003] Embodiments described herein relate to electrochemical cells including heating elements and methods for operating and monitoring them. In some aspects, the electrochemical cell includes an anode current collector, an anode material disposed on the anode current collector, a cathode current collector, a cathode material disposed on a first side of the cathode current collector, a separator disposed between the anode material and the cathode material, and a heating element disposed on a second side of the cathode current collector opposite the first side. In some embodiments, the heating element may include a conductive material. In some embodiments, the heating element may include a conductive material and an insulating material. In some embodiments, an electrochemical cell comprises a first current collector, a first electrode material disposed on a first side of the current collector, a second current collector, a second electrode material disposed on the second current collector, a separator disposed between the first electrode material and the second electrode material, an insulating layer disposed on a second side of the first current collector opposite the first side, and a metal sheet disposed on the insulating layer and electrically coupled in series with the first current collector, the metal sheet including grooves for heat dissipation. In some embodiments, an electrochemical cell includes a first current collector, a first electrode material disposed on a first side of the first current collector, a second current collector, a second electrode material disposed on the second current collector, a separator disposed between the first and second electrode materials, an insulating layer disposed on a second side of the first current collector opposite the first side, and a metal wire disposed inside the insulating layer following a circuit path, the metal wire being connected in series with the first current collector. [Brief explanation of the drawings]

[0005] [Figure 1] FIG. 1 is a block diagram of an electrochemical cell including a heating element, according to one embodiment. [Figure 2] FIG. 2 is a block diagram of a heating element, according to one embodiment. [Figure 3A] 1 is an electrochemical cell including a heating element, according to one embodiment. [Figure 3B]FIG. 3B is an exploded view of the electrochemical cell of FIG. 3A. [Figure 4A] 1 is an electrochemical cell including a heating element, according to one embodiment. [Figure 4B] FIG. 4B is an exploded view of the electrochemical cell of FIG. 4A. [Figure 5A] 1 is an electrochemical cell including a heating element, according to one embodiment. [Figure 5B] FIG. 5B is an exploded view of the electrochemical cell of FIG. 5A. [Figure 6A] FIG. 1 is a circuit diagram of an electrochemical cell stack including a heating element. [Figure 6B] FIG. 1 is a circuit diagram of an electrochemical cell having a heating element that generates heat when the electrochemical cell is being balanced. [Figure 7] 1 is a schematic flow chart of a method for heating an electrochemical cell, according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0006] Embodiments described herein relate to methods for generating, operating, and monitoring electrochemical cells and electrochemical cell stacks. In particular, embodiments described herein relate to electrochemical cells that include a heating element. Many electrochemical cell systems already require a bypass current device to balance and equalize charge within the system. Traditionally, balancing is performed using small resistors on a protection circuit board (PCB or PCBA) that is part of a battery management system (BMS), or through various DC-DC converters that transfer energy from cell to cell, from cell to module, or from cell to secondary energy rail. When electrochemical cells are balanced, thermal energy is generated as current flows through the cells. A major problem with current balancing methods is that the thermal energy from balancing must be absorbed by the PCBA of the BMS, which creates the need to either (1) add cooling to the BMS or (2) dramatically increase the size of the BMS. Balancing electrochemical cells within a PCBA also significantly limits the amount of current available to balance the cells, resulting in very small balancing currents for each BMS board and limited total cell capacity. Generally, any balancing current above 100 mA requires special thermal considerations for the BMS substrate. Therefore, more efficient mechanisms that can be used to dissipate heat from the electrochemical cell will improve overall cell performance.

[0007] To address the above challenges, embodiments described herein include electrochemical cells with heating elements integrated into the electrochemical cell. In some embodiments, the heating element may include a thin metal sheet including a conductive coating and / or an insulating layer disposed on a current collector within the electrochemical cell. In some embodiments, grooves or notches may be etched into the thin metal sheet so that the thin metal sheet has a desired impedance. In some embodiments, the heating element may instead include a metal wire disposed within an insulating layer electrically connected to a current collector within the electrochemical cell, the metal wire following a circuit path to achieve the desired impedance. Because the heating element can be controlled by an existing BMS system, few additional components are required at both the cell, module, and pack levels, thereby reducing system complexity and limiting additional costs. The heating element may provide heat to the electrochemical cell, allowing it to charge at a lower temperature. The heating element may also provide increased thermal mass for dissipation of heat generated by balancing the current, thereby allowing higher balancing currents to be used. The embodiments described herein may allow for direct heating of the electrochemical cell or electrochemical cell stack, thereby improving heating efficiency and reducing heat loss to the surrounding environment.

[0008] A control system for bypassing energy (both charging and discharging) around the module, cell, or pack can ensure safe operation, preventing overcharging and allowing the full formation of each cell. The safety system can monitor temperature, current, and / or voltage to prevent cell damage and thermal runaway due to overheating, overcharging, or over-discharging.

[0009] A safety system may also be used to activate the heating element(s) in response to an internal or external signal. Activating the heating element(s) may be used to reduce the total energy of the system to a lower state of charge. The lower state of charge may be selected based on many conditions, such as, but not limited to, a vehicle collision or airport transport mode. In the event of a vehicle collision, it may be advantageous to activate the heating element(s) (even though this may increase the temperature of the system). This is to fully discharge the battery system (i.e., reduce the charge of the battery system) to prevent potential battery fires when the vehicle is transported or deployed. In the event of airport transport, it may be desirable to reduce the battery energy through mode selection, such as a physical button, or through selection from a human interface, to safely discharge the battery to a lower energy level, reducing the battery's energy content to a safe level, such as less than 30% SOC. Other target states of charge may be selected based on many factors. The selection of 30% is based on the restrictions on air transport of lithium-ion batteries imposed at the time of this application.

[0010] The embodiments described herein may include algorithms that use sensors to detect cell-level failures, internal shorts, and other failure modes. Sensing may be used to sense or determine cell voltage, temperature, current, module-level voltage, module-level temperature, module-level current, pack-level voltage, pack-level temperature, and / or pack-level current. Algorithms may then be used to diagnose the functional status of each cell in the system. In some cases, sensing may be achieved via a battery management system (BMS), test system sensing, a secondary sensing system, or any combination thereof. Safety systems may include area temperature (hot spots), fire detection, smoke detection, hydrogen detection, carbon monoxide (CO) detection, carbon dioxide (CO) detection, volatile organic compound (VOC) detection, and / or other detection methods to ensure the system is intact or to prevent damage to the system, batteries, and facility during development. Safety systems may include fire suppression systems to prevent facility damage, active ventilation systems to prevent facility damage and personal injury, and protection systems to provide propagation protection between cells, modules, and / or battery packs during development.

[0011] In some embodiments, the energy storage system can include a grid or renewable connection to meter energy to the formation system and provide energy that accounts for efficiency losses. In some embodiments, the energy storage system with building controls can monitor facility and campus-wide power demand to provide demand load, frequency regulation, peak shaving, load leveling, and / or other grid maintenance actions. In some embodiments, the energy storage system can serve the formation system and / or other secondary renewable uses, such as charging station power for plug-in hybrid electric vehicles (PHEVs), electric vehicles (EVs), or any other suitable implementation.

[0012] In some embodiments, the electrodes described herein can comprise conventional solid electrodes. In some embodiments, the solid electrodes can comprise a binder. In some embodiments, the electrodes described herein can comprise semi-solid electrodes. The semi-solid electrodes described herein can be made thicker (e.g., greater than 100 μm, up to 2,000 μm, or even greater) due to reduced tortuosity and increased conductivity of the semi-solid electrodes, (ii) with higher active material loading, and (iii) through simplified manufacturing processes utilizing less equipment. These relatively thick semi-solid electrodes reduce the volume, mass, and cost contribution of inactive components relative to the active components, thereby enhancing the commercial attractiveness of batteries made with semi-solid electrodes. In some embodiments, the semi-solid electrodes described herein are binderless and / or do not use binders used in conventional battery manufacturing. Instead, the volume of the electrode typically occupied by a binder in conventional electrodes is now occupied by: 1) the electrolyte. 1) an active material, which reduces tortuosity and increases the total salt available for ion diffusion, thereby countering the salt depletion effect inherent in thick, conventional electrodes when used at high rates; 2) an active material, which increases the charge capacity of the battery; or 3) a conductive additive, which increases the electronic conductivity of the electrode, thereby countering the high internal impedance of thick, conventional electrodes. The reduced tortuosity and increased electronic conductivity of the semi-solid electrodes described herein result in superior rate capabilities and charge capacities for electrochemical cells formed from the semi-solid electrodes. Because the semi-solid electrodes described herein can be made substantially thicker than conventional electrodes, the ratio of active material (i.e., semi-solid cathode and / or anode) to inactive material (i.e., current collector and separator) can be much higher in batteries formed from electrochemical cell stacks containing semi-solid electrodes compared to similar batteries formed from electrochemical cell stacks containing conventional electrodes. This results in a substantial increase in the overall charge capacity and energy density of batteries containing the semi-solid electrodes described herein.

[0013] 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 binderless 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. Stated another way, the active electrode particles and conductive particles are co-suspended in the electrolyte to produce a semi-solid electrode. Examples of battery architectures utilizing semi-solid suspensions are described in U.S. Patent Publication No. 2022 / 0238923 (the "'923 Publication"), filed January 21, 2022, and entitled "Production of Semi-Solid Electrodes Via Addition of Electrolyte to Mixture of Active Material, Conductive Material, and Electrolyte Solvent," and Provisional Patent Application No. 63 / 354,056 (the "'056 Application"), filed June 21, 2022, and entitled "Electrochemical Cells with High-Viscosity Semi-solid Electrodes, and Methods of Making the Same," the disclosures of which are incorporated herein by reference in their entireties.

[0014] In some embodiments, the electrochemical cells described herein can include components that may have multiple layers and / or be coated with one or more materials. Examples of electrodes with multiple layers and / or composition gradients can be found in U.S. Patent 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. Examples of electrochemical cells and electrodes with selectively permeable membranes are described in U.S. Patent Publication No. 2019 / 0348705 (the "'705 publication"), filed January 8, 2019, entitled "Electrochemical Cells Including Selectively Permeable Membranes, Systems and Methods of Manufacturing the Same," the disclosure of which is incorporated herein by reference in its entirety.

[0015] In some embodiments, the power management systems described herein can include any of the aspects described in U.S. Patent No. 10,153,651 (the "'651 patent"), filed October 9, 2015, and entitled "Systems and Methods for Battery Charging," the disclosure of which is incorporated herein by reference in its entirety. In some embodiments, the battery management systems described herein can include any of the aspects described in U.S. Patent Publication No. 2022 / 0278427 (the "'427 publication"), filed May 13, 2022, and entitled "Electrochemical Cells Connected in Series in a Single Pouch and Methods of Making the Same," the disclosure of which is incorporated herein by reference in its entirety.

[0016] As used herein, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, the term "element" is intended to mean a single element or a combination of elements, and "material" is intended to mean one or more materials, or a combination thereof.

[0017] 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 "substantially linear" is intended to convey that while linearity of the portion is desirable, 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). 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.

[0018] As used herein, the terms "set" and "plurality" can refer to multiple features or a singular feature with multiple portions. For example, when referring to a set of electrodes, the set of electrodes can be considered one electrode with multiple portions, or the set of electrodes can be considered multiple separate electrodes. Additionally, for example, when referring to multiple electrochemical cells, the multiple electrochemical cells can be considered 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 contiguous or discontinuous with one another. Multiple particles or multiple materials can also be made from multiple articles that are produced separately and then joined together (e.g., by mixing, adhesive, or any suitable method).

[0019] 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.

[0020] As used herein, the terms "activated carbon network" and "network carbon" refer to the general qualitative state of an electrode. For example, an electrode with an activated carbon network (or network carbon) is one in which the carbon particles within the electrode assume a discrete particle morphology and arrangement that facilitates electrical contact and conductivity between particles and throughout the thickness and length of the electrode. Conversely, the terms "non-activated carbon network" and "non-network 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.

[0021] 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, electrolytes, and current collectors. Specifically, materials used to package the electrochemical cell are excluded from the calculation of volumetric energy density.

[0022] As used herein, the terms "high capacity material" or "high capacity anode material" refer to materials having an irreversible capacity greater than 300 mAh / g that can be incorporated into an electrode to promote 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 (such as CoO, FeO), or titanium oxide.

[0023] As used herein, the term "composite high capacity electrode layer" refers to an electrode layer having both a high capacity material and a conventional anode material, for example, a silicon graphite layer.

[0024] 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 (such as CoO, FeO), or titanium oxide.

[0025] 1 is a block diagram of an electrochemical cell 100, according to one embodiment. As shown, the electrochemical cell 100 includes an anode material 110 disposed on an anode current collector 120, a cathode material 130 disposed on a first side of a cathode current collector 140, a separator 150 disposed between the anode material 110 and the cathode material 130, and a heating element 160 disposed on a second side of the cathode current collector 140 opposite the first side. In some embodiments, the anode material 110 and / or the cathode material 130 can include a semi-solid electrode material, as described above. In some embodiments, the heating element 160 can be disposed on the first side of the anode current collector 120. The heating element 160 can be electrically connected to the cathode current collector 140 and can generate heat for the electrochemical cell 100 when an electric current is passed through the electrochemical cell 100. Additionally, heating element 160 may provide increased thermal mass to improve heat dissipation when current is passed through electrochemical cell 100. As shown, heating element 160 is electrically connected to cathode current collector 140 and is directly adjacent to cathode current collector 140 in circuit. In some embodiments, heating element 160 may be electrically connected to anode current collector 120 and may be directly adjacent to anode current collector 120 in circuit.

[0026] FIG. 2 illustrates a heating element 260 including a resistive element 270, a conductive material 268, and an insulating material 265. In some embodiments, the resistive element 270 may be formed from a conductive material. The conductive material may include, for example, copper, aluminum, silver, nickel, gold, or any suitable combination thereof. The resistive element 270 may be formed according to any suitable form factor, including, but not limited to, a sheet or foil of uniform thickness, a sheet or foil of non-uniform thickness, a discontinuous sheet or foil (e.g., having holes or cutouts), a wire, and / or combinations thereof. In some embodiments, the resistive element 270 may be coated with the conductive material 268 on at least one of a first side and a second side of the resistive element 270. In some embodiments, the conductive material 268 may be coated on the first side of the insulating material 265. The conductive material 268 may facilitate or enhance heating of the heating element 260 when an electric current is passed through the resistive element 270. The heating element 260 may include the insulating material 265. In some embodiments, insulating material 265 may include a pouch surrounding resistive element 270 or a single layer disposed between the current collector and resistive element 270. Insulating material 265 may function to isolate resistive element 270 from the electrical components of the cell (e.g., terminals, electrodes, active material, electrolyte, etc.).

[0027] 3A-3B are diagrams of an electrochemical cell 300 including a heating element 360, according to one embodiment. FIG. 3A shows a cross-sectional profile view of the electrochemical cell 300. FIG. 3B shows an exploded view of the components of the electrochemical cell 300. As shown in FIG. 3A, the electrochemical cell 300 includes an anode material 310 disposed on an anode current collector 320, a cathode material 330 disposed on a cathode current collector 340, and a separator 350 disposed between the anode material 310 and the cathode material 330. The electrochemical cell 300 further includes a resistive element 370 having a conductive material 368 disposed on a first side of the resistive element 370, an insulating material 365 disposed between the resistive element 370 and the cathode current collector 340, and a pouch material 380 disposed around the electrochemical cell 300. In some embodiments, the anode material 310, anode current collector 320, cathode material 330, cathode current collector 340, and separator 350 can be substantially similar to or the same as the anode material 110, anode current collector 120, cathode material 130, cathode current collector 140, and separator 150 described above with reference to Figure 1. Accordingly, certain aspects of the anode material 310, anode current collector 320, cathode material 330, cathode current collector 340, and separator 350 will not be described in further detail herein.

[0028] 3A and 3B, resistive element 370 may be a thin sheet or foil of conductive material including a surface having grooves or channels 372. The conductive material may include, for example, copper, aluminum, silver, nickel, gold, or any suitable combination thereof. The grooves 372 may be etched (ablated, scribed, engraved, cut, melted, stamped, engraved, debossed, etc.) into resistive element 370 in a particular pattern to modify the impedance of resistive element 370, thereby modifying the resistive element's capacity to generate heat in response to the amount of current passed through electrochemical cell 300. Thus, grooves 372 are thinned portions of resistive element 370 compared to the remainder of resistive element 370 (i.e., the non-grooved portions of resistive element 370).

[0029] The ratio of the thickness of the resistance member 370 in the grooves 372 to the thickness of the resistance member 370 in the non-groove portions may be between about 0.1 and 1. The thickness ratio between the grooved and non-groove portions can be at least about 0.10, at least about 0.15, at least about 0.20, at least about 0.25, at least about 0.30, at least about 0.35, at least about 0.40, at least about 0.45, at least about 0.50, at least about 0.55, at least about 0.60, at least about 0.65, at least about 0.70, at least about 0.75, at least about 0.80, at least about 0.85, at least about 0.90, or at least about 0.95. In some embodiments, the thickness ratio between the grooved and non-grooved portions can be about 1 or less, about 0.95 or less, about 0.90 or less, about 0.85 or less, about 0.80 or less, about 0.75 or less, about 0.70 or less, or about 0.65 or less, about 0.60 or less, about 0.55 or less, about 0.50 or less, about 0.45 or less, about 0.40 or less, about 0.35 or less, about 0.30 or less, about 0.25 or less, about 0.20 or less, about 0.15 or less, or about 0.15 or less. Combinations of the above thickness ratios of the resistance member 370 are also possible (e.g., at least about 0.25 or more and about 0.95 or less, or at least about 0.50 or more and about 0.75 or less), including all values and ranges therebetween.

[0030] The resistance member 370 has a length L R and width W R In some embodiments, L R can be at least about 1 cm, at least about 2 cm, at least about 3 cm, at least about 4 cm, at least about 5 cm, at least about 6 cm, at least about 7 cm, at least about 8 cm, at least about 9 cm, at least about 10 cm, at least about 20 cm, at least about 30 cm, at least about 40 cm, at least about 50 cm, at least about 60 cm, at least about 70 cm, at least about 80 cm, or at least about 90 cm. In some embodiments, L Rcan be about 1 m or less, about 90 cm or less, about 80 cm or less, about 70 cm or less, about 60 cm or less, about 50 cm or less, about 40 cm or less, about 30 cm or less, about 20 cm or less, about 10 cm or less, about 9 cm or less, about 8 cm or less, about 7 cm or less, about 6 cm or less, about 5 cm or less, about 4 cm or less, about 3 cm or less, or about 2 cm or less. Combinations of the above lengths are also possible (e.g., at least about 1 cm or more and about 1 m or less, or at least about 3 cm or more and about 10 cm or less), including all values and ranges therebetween. In some embodiments, L R can be about 1 cm, about 2 cm, about 3 cm, about 4 cm, about 5 cm, about 6 cm, about 7 cm, about 8 cm, about 9 cm, about 10 cm, about 20 cm, about 30 cm, about 40 cm, about 50 cm, about 60 cm, about 70 cm, about 80 cm, about 90 cm, or about 1 m.

[0031] In some embodiments, W R can be at least about 5 mm, at least about 6 mm, at least about 7 mm, at least about 8 mm, at least about 9 mm, at least about 1 cm, at least about 2 cm, at least about 3 cm, at least about 4 cm, at least about 5 cm, at least about 6 cm, at least about 7 cm, at least about 8 cm, at least about 9 cm, at least about 10 cm, at least about 20 cm, at least about 30 cm, or at least about 40 cm. R can be about 50 cm or less, about 40 cm or less, about 30 cm or less, about 20 cm or less, about 10 cm or less, about 9 cm or less, about 8 cm or less, about 7 cm or less, about 6 cm or less, about 5 cm or less, about 4 cm or less, about 3 cm or less, about 2 cm or less, about 1 cm or less, about 9 mm or less, about 8 mm or less, about 7 mm or less, or about 6 mm or less. Combinations of the above widths are also possible (e.g., at least about 5 mm or more and about 50 cm or less, or at least about 2 cm or more and about 10 cm or less), including all values and ranges therebetween. In some embodiments, W Rcan be about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, about 1 cm, about 2 cm, about 3 cm, about 4 cm, about 5 cm, about 6 cm, about 7 cm, about 8 cm, about 9 cm, about 10 cm, about 20 cm, about 30 cm, about 40 cm, or about 50 cm.

[0032] As shown, grooves 372 are provided to direct current through specific paths on resistive member 370. R and L R with gaps between grooves 372 along both sides of W R 372. The grooves 372 create tortuosity in the flow path that electrons follow through the resistive element 370. Tortuosity is defined as the ratio of the actual flow path length (the length of the path the current follows through the resistive element 370) to the linear distance between the ends of the flow path (the linear length from the positive terminal of the resistive element 370 to the negative terminal of the resistive element 370). Therefore, by adding more grooves 372, the tortuosity of the resistive element 370 may be increased. The tortuosity ratio may be proportional to the impedance of the resistive element 370, which may be proportional to the heat generated given a fixed amount of current passing through the resistive element 370. A resistive element 370 that includes more grooves 372 can generate more heat than a resistive element 370 with fewer or no grooves. Additionally, including grooves 372 may increase the surface area of the resistive element 370, thereby increasing the resistive element 370's ability to dissipate heat. In some embodiments, the resistance member 370 may comprise more than one thin sheet or foil. In some embodiments, the resistance member 370 may be a continuous thin sheet or foil without grooves or channels 372.

[0033] The resistance member 370 can have a tortuosity of at least about 1, at least about 1.5, 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, at least about 5, at least about 5.5, at least about 6, at least about 6.5, at least about 7, at least about 7.5, at least about 8, at least about 8.5, at least about 9, at least about 9.5, at least about 10, at least about 20, at least about 30, or at least about 40. In some embodiments, the tortuosity can be about 50 or less, about 40 or less, about 30 or less, about 20 or less, about 10 or less, about 9.5 or less, about 9 or less, about 8.5 or less, about 8 or less, about 7.5 or less, about 7 or less, about 6.5 or less, about 6 or less, about 5.5 or less, about 5 or less, about 4.5 or less, about 4 or less, about 3.5 or less, about 3 or less, about 2.5 or less, about 2 or less, or about 1.5 or less. Combinations of the above ranges are also possible (eg, at least about 5 and up to about 50, or at least about 2 and up to about 10), including all values and ranges therebetween. In some embodiments, the tortuosity can be about 1, about 1.25, about 1.5, about 1.75, about 2, about 2.25, about 2.5, about 2.75, about 3, about 3.25, about 3.5, about 3.75, about 4, about 4.25, about 4.5, about 4.75, about 5, about 5.25, about 5.5, about 5.75, about 6, about 6.25, about 6.5, about 6.75, about 7, about 7.25, about 7.5, about 7.75, about 8, about 8.25, about 8.5, about 8.75, about 9, about 9.25, about 9.5, about 9.75, about 10 cm, about 20 cm, about 30 cm, about 40 cm, or about 50 cm.

[0034] In some embodiments, the resistive element 370 can include a partially conductive, high resistance material (e.g., low carbon loaded slurry, alumina, ceramic composite, etc.) such that the flow of current between the resistive element 370 and the anode current collector 320 and / or the cathode current collector 340 produces the desired heating. In some embodiments, the resistive element 370 can include a highly conductive, low resistance material (e.g., high carbon loaded, metal fill, conductive epoxy, etc.) such that the flow of current across the surface of the resistive element 370 produces the desired heating.

[0035] The resistive element 370 may include a coating of conductive material 368 on at least one of a first side and a second side of the resistive element 370. As shown in FIGS. 3A and 3B , the conductive material 368 is coated on the first side of the resistive element 370, the first side being adjacent to the cathode current collector 340 and other electroactive components of the electrochemical cell 300. In some embodiments, the conductive material may be coated on the second side of the resistive element 370, the second side being opposite the first side (i.e., the second side facing the pouch 380 and the exterior of the electrochemical cell 300). In some embodiments, the conductive material 368 may coat both sides of the resistive element 370. In some embodiments, the conductive material 368 may coat the first side of the insulating material 368. In some embodiments, the conductive material 368 may include a carbon-based material, a conductive metal, and / or a non-metallic material, including a composite or layered material. In some embodiments, the conductive material 368 may include, for example, graphite, carbon powder, pyrolytic carbon, carbon black, carbon fiber, carbon microfiber, carbon nanotubes (CNTs), single-walled CNTs, multi-walled CNTs, fullerene carbon including "buckyballs," graphene sheets and / or aggregates of graphene sheets, any other conductive material, metal, alloy, or combinations thereof.

[0036] Any suitable method may be used to coat the resistive element 370 with the conductive material 368, including, but not limited to, vapor deposition, chemical vapor deposition, physical vapor deposition, atomic layer deposition, metalorganic chemical vapor deposition, nitrogen plasma-assisted deposition, sputter deposition, reactive sputter deposition, electroless deposition, jet deposition, sputtering, melt quenching, mechanical milling, spraying, cold spray processes, plasma deposition processes, electrochemical deposition, sol-gel processes, evaporation, or any combination thereof. In some embodiments, the conductive coating 368 can be applied to the resistive element 370 by a liquid coating process, such as applying or painting a liquid slurry, or an extrusion process with or without a hot / cold pressing process. In some embodiments, the conductive material 368 can be applied to the separator by casting, laminating, calendaring, drop coating, pressing, roll pressing, tape casting, or any combination thereof. In some embodiments, the conductive material 368 can be applied by any of the methods described in the '351 publication and / or the '705 publication. The conductive material 368 may facilitate or enhance heating of the heating element 360 when an electrical current is passed through the resistive member 370. In some embodiments, the conductive material 368 may be a separate layer from the resistive member 370.

[0037] In some embodiments, the conductive material 368 can have a thickness of at least about 100 nm, at least about 200 nm, at least about 300 nm, at least about 400 nm, at least about 500 nm, at least about 600 nm, at least about 700 nm, at least about 800 nm, at least about 900 nm, at least about 1 μm, at least about 2 μm, at least about 3 μm, at least about 4 μm, at least about 5 μm, at least about 6 μm, at least about 7 μm, at least about 8 μm, at least about 9 μm, at least about 10 μm, at least about 11 μm, at least about 12 μm, at least about 13 μm, at least about 14 μm, at least about 15 μm, at least about 16 μm, at least about 17 μm, at least about 18 μm, or at least about 19 μm. In some embodiments, the conductive material 368, when disposed on the first and / or second sides of the resistive member 370, can have a thickness of about 20 μm or less, about 19 μm or less, about 18 μm or less, about 17 μm or less, about 16 μm or less, about 15 μm or less, about 14 μm or less, about 13 μm or less, about 12 μm or less, about 11 μm or less, about 10 μm or less, about 9 μm or less, about 8 μm or less, about 7 μm or less, about 6 μm or less, about 5 μm or less, about 4 μm or less, about 3 μm or less, about 2 μm or less, about 1 μm or less, about 900 nm or less, about 800 nm or less, about 700 nm or less, about 600 nm or less, about 500 nm or less, about 400 nm or less, about 300 nm or less, or about 200 nm or less. Combinations of the above thicknesses of conductive material 368 are also possible (eg, at least about 100 nm to about 20 μm, or at least about 1 μm to about 5 μm), including all values and ranges therebetween. In some embodiments, the conductive material 368, when disposed on the first and / or second sides of the resistive member 370, can have a thickness of about 100 nm, about 200 nm, about 300 nm, about 400 nm, about 500 nm, about 600 nm, about 700 nm, about 800 nm, about 900 nm, about 1 μm, about 2 μm, about 3 μm, about 4 μm, about 5 μm, about 6 μm, about 7 μm, about 8 μm, about 9 μm, about 10 μm, about 11 μm, about 12 μm, about 13 μm, about 14 μm, about 15 μm, about 16 μm, about 17 μm, about 18 μm, about 19 μm, or about 20 μm.

[0038] In some embodiments, the conductive material 368 has a conductivity of at least about 1.2 g / cm 3 , at least about 1.3 g / cm 3 , at least about 1.4 g / cm 3 , at least about 1.5 g / cm 3 , at least about 1.6 g / cm 3 , at least about 1.7 g / cm 3 , at least about 1.8 g / cm 3 , or at least about 1.9 g / cm 3 In some embodiments, the conductive material 368 may have a density of about 2 g / cm 3 Below, approximately 1.9g / cm 3 Below, about 1.8g / cm 3 Below, approximately 1.7g / cm 3 Below, approximately 1.6g / cm 3 Below, about 1.5g / cm 3 Below, about 1.4g / cm 3 or less, or about 1.3 g / cm 3 Combinations of the above densities for the layer of conductive material 368 are also possible (e.g., at least about 1.2 g / cm 3 Approximately 2g / cm or more 3 or less, or at least about 1.3 g / cm 3 Approximately 2g / cm or more 3 hereinafter), including all values and ranges therebetween. In some embodiments, the conductive material 368 has a viscosity of about 1.2 g / cm 3 , about 1.3g / cm 3 , approximately 1.4 g / cm 3 , about 1.5g / cm 3 , about 1.6g / cm 3 , about 1.7g / cm 3 , about 1.8g / cm 3 , about 1.9g / cm 3 , or about 2 g / cm 3 The density of the granular material may be 0.05 to 0.15.

[0039] In some embodiments, the conductive material 368 is at least about 10 nm, at least about 20 nm, at least about 30 nm, at least about 40 nm, at least about 50 nm, at least about 60 nm, at least about 70 nm, at least about 80 nm, at least about 90 nm, at least about 100 nm, at least about 200 nm, at least about 300 nm, at least about 400 nm, at least about 500 nm, at least about 600 nm, at least about 700 nm, at least about 800 nm, at least about 900 nm, The particles may include particles having an average particle size (i.e., D50) of at least about 1 μm, at least about 2 μm, at least about 3 μm, at least about 4 μm, at least about 5 μm, at least about 6 μm, at least about 7 μm, at least about 8 μm, at least about 9 μm, at least about 10 μm, at least about 11 μm, at least about 12 μm, at least about 13 μm, at least about 14 μm, at least about 15 μm, at least about 16 μm, at least about 17 μm, at least about 18 μm, or at least about 19 μm. In some embodiments, the conductive material 368 has a thickness of about 20 μm or less, about 19 μm or less, about 18 μm or less, about 17 μm or less, about 16 μm or less, about 15 μm or less, about 14 μm or less, about 13 μm or less, about 12 μm or less, about 11 μm or less, about 10 μm or less, about 9 μm or less, about 8 μm or less, about 7 μm or less, about 6 μm or less, about 5 μm or less, about 4 μm or less, about 3 μm or less, about 2 μm or less, about 1 μm or less, The particles may include particles having an average particle size of about 900 nm or less, about 800 nm or less, about 700 nm or less, about 600 nm or less, about 500 nm or less, about 400 nm or less, about 300 nm or less, about 200 nm or less, about 100 nm or less, about 90 nm or less, about 80 nm or less, about 70 nm or less, about 60 nm or less, about 50 nm or less, about 40 nm or less, about 30 nm or less, or about 20 nm or less.

[0040] Combinations of the above particle sizes are also possible (eg, at least about 10 nm to about 20 μm, or at least about 1 μm to about 5 μm), including all values and ranges therebetween. In some embodiments, the conductive material 368 can include particles having an average particle size of about 10 nm, about 20 nm, about 30 nm, about 40 nm, about 50 nm, about 60 nm, about 70 nm, about 80 nm, about 90 nm, about 100 nm, about 200 nm, about 300 nm, about 400 nm, about 500 nm, about 600 nm, about 700 nm, about 800 nm, about 900 nm, about 1 μm, about 2 μm, about 3 μm, about 4 μm, about 5 μm, about 6 μm, about 7 μm, about 8 μm, about 9 μm, about 10 μm, about 11 μm, about 12 μm, about 13 μm, about 14 μm, about 15 μm, about 16 μm, about 17 μm, about 18 μm, or about 19 μm, or about 20 μm.

[0041] The heating element may include an insulating material 365. In some embodiments, a conductive material 368 may coat a first side of the insulating material 368, with the first side of the insulating material 368 facing the resistive element 370. The resistive element 370 may be packaged in an electrically insulating layer or assembly, or may be packaged with the electrochemical cell 300. In some embodiments, the insulating material 365 can be a pouch surrounding the resistive element 370 and the conductive material 368, or a single layer disposed between the resistive element 370 and other components of the electrochemical cell 300. The insulating material 365 may function to isolate the conductive coating 368 from the electrical components of the electrochemical cell 300 (e.g., terminals, electrodes, active material, electrolyte, etc.). The insulating material 365 may be formed from any suitable material, including, for example, polycarbonate, polyethylene, polypropylene, polyimide, mica, polystyrene, fiberglass, FORMEX™, any other suitable insulating material, or combinations thereof. In some embodiments, the heating element may include a plurality of resistive elements 360 disposed within an insulating material 365. In some embodiments, the heating element may include approximately 2 resistive elements, 3 resistive elements, 4 resistive elements, 5 resistive elements, 6 resistive elements, 7 resistive elements, 8 resistive elements, 9 resistive elements, or 10 resistive elements.

[0042] In some embodiments, electrochemical cell 300 may be disposed within insulating pouch 380. Insulating pouch 380 may have a first film disposed over heating element 360 and a second film disposed under anode current collector 320, with the first and second films bonded together to form the pouch. In some embodiments, heating element 360 may instead be disposed on the exterior surface of insulating pouch 380. In some embodiments, heating element 360, including resistive member 370 and conductive material 368, may be integrated into insulating pouch 380. In some embodiments, conductive material 368 is integrated into or deposited on the interior surface of insulating pouch 380. In some embodiments, conductive material 368 is integrated into or deposited on the exterior surface of insulating pouch 380. Insulating pouch 380 may prevent unwanted current from passing between multiple serially connected electrochemical cells during operation of the electrochemical cell. Insulating pouch 380 may be formed from any suitable material, including, for example, polycarbonate, polyethylene, polypropylene, polyimide, mica, polystyrene, fiberglass, FORMEX™, any other suitable insulating material, or combinations thereof. Electrochemical cell 300 and insulating pouch 380 may be disposed within a structure such as an outer pouch, casing, or housing (not shown). In some embodiments, multiple electrochemical cells may be housed in a stacking pouch (not shown). In some embodiments, the stacking pouch may include an aluminized pouch. In some embodiments, heating element 360 may instead be disposed on the exterior surface of the stacking pouch. In some embodiments, the heating element, including resistive member 360 and conductive material 368, may be integrated into the stacking pouch. In some embodiments, conductive material 368 may be integrated into the interior surface of the stacking pouch. In some embodiments, conductive material 368 may be integrated into the exterior surface of the stacking pouch.

[0043] As shown, the cathode current collector 340, the resistive element 370, and the conductive material 368 may extend away from or outward from the first end of the electrochemical cell 300 to form one or more tabs that may be accessible from outside the outer pouch. In some embodiments, the anode current collector 320 may include a tab that extends away from or outward from the first end of the electrochemical cell 300. The tab may function as a voltage measurement point for battery monitoring or as a connection point through which the electrochemical cell 300 may be electrically connected in series to other electrochemical cells. The tab may further function as a connection point through which the electrochemical cell 300 may be connected to an electronic circuit, such as a battery management system (BMS) (not shown). The BMS may include a circuit board (PCB or PCBA) and may be used, for example, to control the current through the cell to monitor the cell, balance the cell, or control the heat generated by the cell. In some embodiments, balancing of the electrochemical cell 300 may be performed at the tab via the BMS.

[0044] Balancing the electrochemical cell 300 may be beneficial when the electrochemical cell is part of a stack of electrochemical cells. Balancing involves removing charge from or adding charge to the electrochemical cell 300 (e.g., balancing current) to ensure that the voltage of any one of the electrochemical cells does not emanate from the pack. Balancing the electrochemical cells may generate heat, which may be absorbed by the PCB of the BMS. The design of the electrochemical cell 300 may assist in the distribution of thermal energy. The design may then allow for an increase in the current available for balancing. The amount of available balancing current may be directly proportional to the cell capacity. The design of the electrochemical cell 300 may allow for the balancing current to be adjusted to meet the system voltage demands and manage the system temperature. Increased thermal mass may assist in the dissipation of the balancing current. The thermal mass may be directly proportional to the available balancing energy. In some embodiments, an existing cooling system (not shown) may remove heat from the electrochemical cell 300. Incorporation of the heating element 370 can reduce the number of components required at the module and battery pack level (e.g., thermal pads and / or water heaters can be eliminated). The heating element also leads to improved heating efficiency with less loss to the surrounding environment (i.e., heat goes directly to the electrochemical cell 300).

[0045] In some embodiments, the heating element may result in a slight increase in system cost (i.e., the additional cost of additional conductive material and carbon). However, the manufacturing method can be implemented without new equipment. In some embodiments, construction of electrochemical cell 300 can use existing connection methods for cell production, with one additional connection for heating element 370. In some embodiments, resistive element 370 may be purchased in an existing form from a service application, such as a food packaging or cell pouch material supplier containing an aluminum film layer, to further reduce manufacturing complexity and cost.

[0046] 4A-4B are diagrams of an electrochemical cell 400 including a heating element 460, according to one embodiment. FIG. 4A shows a cross-sectional profile view of elements of the electrochemical cell 400. FIG. 4B shows an exploded view of the electrochemical cell 400. As shown in FIG. 4A, the electrochemical cell 400 includes an anode material 410 disposed on an anode current collector 420, a cathode material 430 disposed on a cathode current collector 440, and a separator 450 disposed between the anode material 410 and the cathode material 430. The electrochemical cell 400 further includes a resistive element 470 having a conductive material 468 disposed on a first side of the resistive element 470, an insulating material 465 disposed between the resistive element 470 and the cathode current collector 440, and a pouch material 480 disposed around the electrochemical cell 400. The electrochemical cell 400 includes a first end and a second end. The cathode current collector 440, the resistive element 470, and / or the conductive material 468 may extend away or outward from the first end of the electrochemical cell 400 to form one or more tabs.

[0047] 4B, resistive element 470 may be a thin sheet or foil of conductive material with sections of the thin sheet or foil completely removed (e.g., cutouts, holes, gaps) to modify the impedance of resistive element 470. Resistive element 470 has a length L R and width W R Similar to the grooves described above, the notches 472 may be removed in a specific pattern to modify the impedance of the resistive element 470, thereby allowing a predetermined amount of heat to be generated through the resistive element 470 given a certain amount of current passing through the electrochemical cell 400. As shown, W RSections of the resistive element 470 that extend horizontally along the notch 473 may be removed. The notches 472 function similarly to the grooves 372, allowing the tortuosity of the conductive material to be adjusted. By adjusting how sections are removed from the resistive element 470, the tortuosity of the resistive element 470 may be increased, thereby increasing the resistive element 470's ability to generate heat. A resistive element 470 with the notches 473 may generate more heat than a resistive element with fewer or no notches. The resistive element 470 may be purchased in an existing form from a service application, such as a food packaging or cell pouch material supplier containing an aluminum film layer, to reduce manufacturing complexity and cost. The sections of the resistive element 470 may be removed using standard PCB fabrication methods or using standard flexible circuit technology.

[0048] The resistance member 470 can have a tortuosity of at least about 1, at least about 1.5, 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, at least about 5, at least about 5.5, at least about 6, at least about 6.5, at least about 7, at least about 7.5, at least about 8, at least about 8.5, at least about 9, at least about 9.5, at least about 10, at least about 20, at least about 30, at least about 40, or at least about 50. In some embodiments, the tortuosity can be about 50 or less, about 40 or less, about 30 or less, about 20 or less, about 10 or less, about 9 or less, about 8 or less, about 7 or less, about 6 or less, about 5 or less, about 4 or less, about 3 or less, about 2 or less, or about 1 or less. Combinations of the above ranges are also possible (e.g., at least about 5 or more and about 50 or less, or at least about 2 or more and about 10 or less), including all values and ranges therebetween. In some embodiments, the tortuosity can be about 1, about 1.25, about 1.5, about 1.75, about 2, about 2.25, about 2.5, about 2.75, about 3, about 3.25, about 3.5, about 3.75, about 4, about 4.25, about 4.5, about 4.75, about 5, about 5.25, about 5.5, about 5.75, about 6, about 6.25, about 6.5, about 6.75, about 7, about 7.25, about 7.5, about 7.75, about 8, about 8.25, about 8.5, about 8.75, about 9, about 9.25, about 9.5, about 9.75, about 10 cm, about 20 cm, about 30 cm, about 40 cm, or about 50 cm.

[0049] In some embodiments, the anode 410, anode current collector 420, cathode 430, cathode current collector 440, separator 450, resistive element 470, conductive material 468, and insulating material 465 can be substantially similar to or the same as the anode 310, anode current collector 320, cathode 330, cathode current collector 340, separator 350, resistive element 370, conductive material 368, and insulating material 365 described above with reference to Figure 3. Accordingly, certain aspects of the anode 410, anode current collector 420, cathode 430, cathode current collector 440, and separator 450, resistive element 470, conductive material 468, and insulating material 465 will not be described in further detail herein.

[0050] 5A-5B are diagrams of an electrochemical cell 500 including a heating element 560, according to one embodiment. FIG. 5A shows a cross-sectional profile view of elements of the electrochemical cell 500. FIG. 5B shows an exploded view of the electrochemical cell 500. As shown in FIG. 5A, the electrochemical cell 500 includes an anode material 510 disposed on an anode current collector 520, a cathode material 530 disposed on a cathode current collector 540, and a separator 550 disposed between the anode material 510 and the cathode material 430. The electrochemical cell 500 further includes a resistive element 570 having a conductive material 568 coating the resistive element 570, an insulating material 565 disposed between the resistive element 570 and the cathode current collector 540, and a pouch material 580 disposed around the electrochemical cell 500. The electrochemical cell 500 includes a first end and a second end. The cathode current collector 540, the resistive member 570, and / or the conductive material 568 may extend away or outward from the first end of the electrochemical cell 500 to form one or more tabs.

[0051] In some embodiments, the resistive element 570 may be a wire with a first terminal end connected in series with a current collector and a second terminal end extending away or outward from the first end of the electrochemical cell 500, where the wire follows a circuitous (serpentine, twisted) path. The properties of the wire, such as cross-sectional area, length, and path, can be adjusted to modify the impedance of the resistive element 570. The wire may be coated with a conductive material 568. By adjusting the path of the wire, the tortuosity of the resistive element 570 may be increased, thereby increasing the ability of the resistive element 570 to generate heat. Additionally, adjusting the cross-sectional area of the wire may also be used to adjust the impedance of the resistive element 570. A shorter length L R A resistance element 570 having more turns and / or a smaller cross-sectional area may generate more heat than a resistance element having fewer turns and / or a larger cross-sectional area.

[0052] In some embodiments, the anode 510, anode current collector 520, cathode 530, cathode current collector 540, separator 550, resistive element 570, conductive material 568, and insulating material 565 can be substantially similar to or the same as the anode 310, anode current collector 320, cathode 330, cathode current collector 340, separator 350, resistive element 370, conductive material 368, and insulating material 365 described above with reference to Figure 3. Accordingly, certain aspects of the anode 510, anode current collector 520, cathode 530, cathode current collector 540, and separator 550, resistive element 570, conductive material 568, and resistive material 565 will not be described in further detail herein.

[0053] FIG. 6A shows a circuit diagram of an electrochemical cell stack 6000 including a heating element, in which the electrochemical cells are connected in parallel. As shown, the heating element may provide an electrical connection between the negative terminal of the electrochemical cell and the BMS to reduce connection points. In some embodiments, a first terminal end of the heating element may be electrically connected to the electrochemical cell, and a second terminal end of the heating element may be electrically connected to the BMS. FIG. 6B is a circuit diagram of an electrochemical cell 600 having a heating element 660 that generates heat when the electrochemical cell 600 is being balanced. As shown, the electrochemical cell 600 has current shunting due to the implementation of the heating element 660.

[0054] 7 is a schematic flow chart of a method for heating an electrochemical cell using a heating element, according to one embodiment. Although described with respect to electrochemical cell 300 including resistive member 370, conductive material 368, and insulating material 365, method 700 is equally applicable to any electrochemical cell including any heating element described herein. All such variations should be considered within the scope of this disclosure.

[0055] At 702, the method 700 includes etching an exterior surface of the resistive element 370 so that the resistive element 370 has a desired impedance. In some embodiments, sections of the resistive element 370 may be completely removed to modify the impedance of the resistive element 370. In some embodiments, the resistive element 370 may instead comprise a wire including a first terminal end connected in series with the current collector 340 of the electrochemical cell 300 and forming a circuit path with a second terminal end extending horizontally outward from the electrochemical cell 300. At 704, the method includes coating the resistive element 370 with a conductive coating 368. At 706, the resistive element 370 may be disposed within an insulating material 365 to isolate the conductive material 368 from the electrical components of the cell. In some embodiments, the insulating material 365 may be a single layer disposed between the resistive element 370 and the current collector 340 of the electrochemical cell 300. In some embodiments, the insulating material 365 may be a pouch disposed around the resistive element 370. At 708, the method includes disposing the resistive element 370 on a first side of the cathode current collector 340. In some embodiments, a heating element is electrically connected to the cathode current collector 340 and directly adjacent to the cathode current collector 340 in a circuit. In some embodiments, the heating element may be electrically connected to the anode current collector 320 and directly adjacent to the anode current collector 320 in a circuit. At 710, the flow of current through the resistive element 370 is controlled using electronic circuitry electrically coupled to the resistive element 370 such that the temperature of the resistive element 370 increases. In some embodiments, the electronic circuitry may be an already-existing BMS including a PCB. In some embodiments, the BMS may be used to monitor the electrochemical cell 300, balance the electrochemical cell 300, and send current through the electrochemical cell 300 to generate heat. In some embodiments, the BMS may include an existing cooling system that may be used to cool the electrochemical cells 300 as heat is generated during balancing of the electrochemical cells 300 .

[0056] Various concepts may be embodied as one or more methods, at least one example of which is provided. Acts performed as part of a method may be ordered in any suitable manner. Thus, although shown as sequential acts in an exemplary embodiment, embodiments may be constructed in which acts are performed in an order different from that illustrated, which may include performing some acts simultaneously. In other words, it should be understood that such features may not necessarily be limited to a particular order of execution, but rather, any number of threads, processes, services, servers, etc. may be executed sequentially, asynchronously, concurrently, in parallel, simultaneously, and / or synchronously in a manner consistent with this disclosure. Thus, some of these features may be mutually inconsistent, in that they cannot exist simultaneously in a single embodiment. Similarly, some features may be applicable to certain aspects of the invention and inapplicable to other aspects.

[0057] Additionally, the present disclosure may include other innovations not currently described. The applicants retain all rights in such inventions, including any rights to practice such inventions and to any additional applications, continuations, continuations-in-part, divisions, 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 construed 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 organization and / or relational models, data types, data transmission and / or network frameworks, syntactic 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.

[0058] All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and / or ordinary meanings of the defined terms.

[0059] As used herein, in certain embodiments, the term "about" or "approximately," when preceding a numerical value, indicates a range of plus or minus 10% of the value. When a range of values is provided, it is understood that, to the tenth of the unit of the lower limit, each intervening value between the upper and lower limit of that range, 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 may independently be included in the smaller ranges, and are subject to any specifically excluded limit in the stated range, also encompassed within the disclosure. Where a stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included within the disclosure.

[0060] As used herein in the specification and embodiments, the term "and / or" should be understood to mean "either or both" of the elements so conjoined, i.e., elements that are present conjunctively in some cases and disjunctively in other cases. Multiple elements listed with "and / or" should be construed 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," can refer in one embodiment to A only (optionally including elements other than B), in another embodiment to B only (optionally including elements other than A), or in yet another embodiment to both A and B (optionally including other elements), etc.

[0061] As used herein in the specification and 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" should be interpreted as inclusive, i.e., including at least one of a number or list of elements, but including more than one, and optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as "only one of" or "exactly one of," or, when used in embodiments, "consisting of," will refer to the inclusion of exactly one element of a number or list of elements. Generally, as used herein, the term "or" should be interpreted as indicating exclusive alternatives (i.e., "one or the other, but not both") only when preceded by terms of exclusivity, such as "either," "one of," "only one of," or "exactly one of." "Consisting essentially of," when used in embodiments, shall have its ordinary meaning as used in the field of patent law.

[0062] As used herein in the specification and embodiments, the phrase "at least one," in reference to a list of one or more elements, should be understood 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 every element specifically listed in the list of elements and 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 related to the specifically identified elements or not, 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, optionally, two or more A, and no B (and, optionally, including elements other than B); in another embodiment, at least one, optionally, two or more B, and no A (and, optionally, including elements other than A); in yet another embodiment, at least one, optionally, two or more A, and at least one, optionally, two or more B (and, optionally, including other elements); etc.

[0063] In 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." As set forth in Section 2111.03 of the United States Patent Office Manual of Patent Examining Procedures, only the transitional phrases "consisting of" and "consisting essentially of" must be closed or semi-closed transitional phrases, respectively.

[0064] 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, as described herein, are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the present disclosure. While the methods and steps described above indicate 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 that such changes are in accordance with variations of the present invention. Additionally, some steps may be performed simultaneously in parallel processing, where possible, rather than simply sequentially as described above. While embodiments have been shown and described in detail, it will be understood that various changes in form and detail may be made.

Claims

1. 1. An electrochemical cell comprising: an anode current collector; an anode material disposed on the anode current collector; a cathode current collector; a cathode material disposed on a first side of the cathode current collector; a separator disposed between the anode material and the cathode material; a heating element disposed on a second side of the cathode current collector opposite the first side, the heating element comprising an electrically conductive material and an electrically insulating material.

2. 10. The electrochemical cell of claim 1, wherein the conductive material comprises a metal sheet containing etched grooves for heat dissipation.

3. 10. The electrochemical cell of claim 1 , wherein the conductive material comprises a metal wire, the metal wire including a first terminal end in contact with the cathode current collector and a second terminal end extending away from the electrochemical cell.

4. 10. The electrochemical cell of claim 1, wherein the conductive material comprises a planar metal sheet having sections removed to create a flow path for electrical current flow.

5. The electrochemical cell of claim 1 , wherein the heating element further comprises a conductive material.

6. 6. The electrochemical cell of claim 5, wherein the conductive material comprises at least one of graphite, carbon powder, pyrolytic carbon, carbon black, carbon fiber, carbon microfiber, carbon nanotubes, fullerene carbon, and one or more graphene sheets.

7. 10. The electrochemical cell of claim 1, wherein the conductive material comprises at least one of aluminum or copper.

8. a first film disposed on the heating element; 10. The electrochemical cell of claim 1 further comprising: a second film disposed on the anode current collector, the second film being bonded to the first film to form a pouch.

9. a first film disposed between the heating element and the cathode current collector; 10. The electrochemical cell of claim 1, further comprising: a second film disposed on the anode current collector, the second film being bonded to the first film to form a pouch, the heating element being disposed on an exterior of the pouch.

10. a first film disposed on the heating element; 10. The electrochemical cell of claim 1 further comprising: a second film disposed on the second current collector, the second film being bonded to the first film to form a pouch.

11. a first film disposed between the heating element and the first current collector; 10. The electrochemical cell of claim 1, further comprising: a second film disposed on the second current collector, the second film being bonded to the first film to form a pouch, the heating element being disposed on an exterior of the pouch.

12. a first film disposed on the heating element; 10. The electrochemical cell of claim 1 further comprising: a second film disposed on the second current collector, the second film being bonded to the first film to form a pouch.

13. a first film disposed between the heating element and the first current collector; 10. The electrochemical cell of claim 1, further comprising: a second film disposed on the second current collector, the second film being bonded to the first film to form a pouch, the heating element being disposed on an exterior of the pouch.

14. 1. An electrochemical cell comprising: a first current collector; a first electrode material disposed on a first side of the first current collector; a second current collector; and a second electrode material disposed on the second current collector; a separator disposed between the first electrode material and the second electrode material; an insulating layer disposed on a second side of the first current collector opposite the first side; a metal sheet disposed on the insulating layer and electrically coupled in series with the first current collector, the metal sheet including grooves for heat dissipation.

15. 15. The electrochemical cell of claim 14, further comprising a conductive material disposed on the metal sheet.

16. 15. The electrochemical cell of claim 14, wherein the conductive material comprises at least one of graphite, carbon powder, pyrolytic carbon, carbon black, carbon fiber, carbon microfiber, carbon nanotubes, fullerene carbon, and one or more graphene sheets.

17. 15. The electrochemical cell of claim 14, wherein the metal sheet comprises at least one of aluminum or copper.

18. 1. An electrochemical cell comprising: a first current collector; a first electrode material disposed on a first side of the first current collector; a second current collector; and a second electrode material disposed on the second current collector; a separator disposed between the first electrode material and the second electrode material; an insulating layer disposed on a second side of the first current collector opposite the first side; a metal wire disposed inside the insulating layer following a circuit path, the metal wire being connected in series with the first current collector.

19. 20. The electrochemical cell of claim 18, wherein the metal wire comprises at least one of aluminum or copper.

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