Electrochemical cells and electrochemical cell stacks having series connections, and methods for producing, operating, and monitoring them

Abstract

In some aspects, a method for monitoring the integrity of an electrochemical cell can include measuring a first anode voltage at a first anode tab from a plurality of anode tabs and a second anode voltage at a second anode tab from the plurality of anode tabs, measuring a first cathode voltage at a first cathode tab from a plurality of cathode tabs and a second cathode voltage at a second cathode tab from the plurality of cathode tabs, and calculating a first sensed voltage that is a difference between the first cathode voltage and the first anode voltage. In some embodiments, a second sensed voltage that is a difference between the second cathode voltage and the second anode voltage can be calculated. In some embodiments, a difference between the first sensed voltage and the second sensed voltage can be calculated.

Description

Technical Field

[0001] Cross - reference to Related Applications This application claims the benefit and priority of U.S. Provisional Patent Application No. 63 / 394,341, filed on Aug. 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 hereby incorporated by reference in its entirety.

[0002] The embodiments described herein relate to electrochemical cells connected in series, and methods of producing, operating, and monitoring them.

Background Art

[0003] In a lithium-ion battery including a plurality of electro-chemical cells electrically connected in series, it is desirable to monitor the voltage of each electro-chemical cell and adjust the balance in order to optimize the overall performance of the battery. The voltage of each electro-chemical cell is monitored to evaluate the healthy state of the cell and ensure that the voltage does not exceed a set limit during charging and discharging of the cell. Due to variations between cells, the electro-chemical cells are also periodically balanced, which includes removing charge from or adding charge to the cells, in order to ensure that the voltages across the cells do not diverge significantly from each other, as significant divergence of the voltage degrades the performance of the battery. In a typical state-of-the-art lithium-ion battery, the monitoring and balance adjustment of individual electro-chemical cells are performed through the same electrical connection point, thereby preventing the ability to simultaneously monitor and balance adjust the electro-chemical cells. Additionally, when sensing the voltage across the connection point that also carries the system current, the measured voltage may have a voltage offset proportional to the flow of the system current. This voltage offset due to the flow of current can cause errors that must be accounted for in filtering and monitoring algorithms. Furthermore, in an electro-chemical cell having a large-area electrode, there may be a voltage gradient within the electrode that affects the voltage measured at a single reference point, thereby reducing the effectiveness of existing balance adjustment and monitoring algorithms. Therefore, there is a need for a mechanism that can be used to more accurately and efficiently monitor and balance adjust electro-chemical cells connected in series.

Summary of the Invention

[0004] The embodiments described herein relate to a method of generating, operating, and monitoring an electro-chemical cell connected in series. In some aspects, a method of operating an electro-chemical cell included in an electro-chemical cell stack having a plurality of electro-chemical cells, each of the electro-chemical cells included in the electro-chemical cell stack including an anode material coupled to an anode current collector having a plurality of anode tabs, a cathode material coupled to a cathode current collector having a plurality of cathode tabs, and a separator disposed between the anode material and the cathode material, the method including measuring an anode voltage difference between a first anode tab from the plurality of anode tabs of the electro-chemical cell and a second anode tab from the plurality of anode tabs of the electro-chemical cell, measuring a cathode voltage difference between a first cathode tab from the plurality of cathode tabs of the electro-chemical cell and a second cathode tab from the plurality of cathode tabs of the electro-chemical cell, and adjusting a balance of the electro-chemical cell relative to other electro-chemical cells included in the electro-chemical cell stack based at least on the values of the anode voltage difference and the cathode voltage difference. In some aspects, a method of monitoring the soundness of an electro-chemical cell can include measuring a first anode voltage at a first anode tab from the plurality of anode tabs, measuring a second anode voltage at a second anode tab from the plurality of anode tabs, measuring a first cathode voltage at a first cathode tab from the plurality of cathode tabs, measuring a second cathode voltage at a second cathode tab from the plurality of cathode tabs, and calculating a first sensed voltage that is a difference between the first cathode voltage and the first anode voltage. In some embodiments, a second sensed voltage that is a difference between the second cathode voltage and the second anode voltage can be calculated. In some embodiments, a difference between the first sensed voltage and the second sensed voltage can be calculated.

[0005] In some embodiments, an electrochemical cell includes an anode material coupled to an anode current collector, a cathode material coupled to a cathode current collector, a separator disposed between the anode material and the cathode material, a plurality of anode tabs electrically connected to the anode current collector such that a first anode voltage can be measured at a first anode tab of the plurality of anode tabs and a second anode voltage can be measured at a second anode tab of the plurality of anode tabs, and a plurality of cathode tabs electrically connected to the cathode current collector such that a first cathode voltage can be measured at a first cathode tab of the plurality of cathode tabs and a second cathode voltage can be measured at a second cathode tab of the plurality of cathode tabs. In some embodiments, the first cathode tab and the first anode tab extend from a proximal end of the electrochemical cell. In some embodiments, the second cathode tab extends from a first horizontal side of the electrochemical cell, the second anode tab extends from a second horizontal side of the electrochemical cell, and the second horizontal side is opposite the first horizontal side.

Brief Description of the Drawings

[0006]

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Mode for Carrying Out the Invention

[0007] The embodiments described herein relate to a method of generating, operating, and monitoring an electrochemical cell. Some embodiments described herein can be used to monitor an electrochemical cell connected in series. In a system including a plurality of electrochemical cells connected in series, such as a lithium-ion battery, the electrochemical cell voltage is typically monitored and balanced to optimize the performance of the battery. The voltage of each electrochemical cell is monitored to evaluate the health of each electrochemical cell and to ensure that the voltage of each electrochemical cell does not exceed the limits set during charging and discharging. Additionally, since electrochemical cells may vary from each other due to small variations in materials and manufacturing, the electrochemical cells can be periodically balanced to eliminate divergence of voltage between the electrochemical cells, as such divergence of voltage may reduce the overall performance of the battery. In an electrochemical cell having a large-area electrode, there may be a voltage gradient within the electrode, which can affect the voltage measured at any single reference point and complicate monitoring and balancing. In existing methods, (1) monitoring and balancing of individual electrochemical cells are performed through the same electrical connection point, which hinders the ability to simultaneously monitor and balance the electrochemical cells, and (2) the voltage gradient within the electrode is estimated by using complex algorithms, and its accuracy may be affected by various factors such as cell aging.

[0008] The embodiments described herein may address the drawbacks of existing methods by including multiple locations at which the voltage of an electrochemical cell may be measured. In some embodiments, multiple anode tabs and multiple cathode tabs may be used to measure the voltage of an electrochemical cell at different locations along the anode and cathode, respectively, thereby enabling direct measurement of the electrode internal gradient rather than estimation of the electrode internal gradient using an algorithm. Additionally, including multiple anode tabs and multiple cathode tabs enables simultaneous monitoring and balance adjustment of any one electrochemical cell, thereby reducing the steps required for battery production or operation. For example, balance adjustment of the electrochemical cell voltage may be performed through a first anode tab and a first cathode tab, while monitoring of the electrochemical cell may be performed through a second anode tab and a second cathode tab. For example, independently monitoring voltage fluctuations with respect to the flow of current within a system may enable additional diagnostic capabilities not available in current state-of-the-art systems. The additional anode tabs and / or cathode tabs described herein may be utilized in both large-format cells and small-format cells as a local connection for a battery management system (BMS), eliminating the need for long connection wires. Thus, the systems and methods described herein may provide additional advantages from the perspective of packaging and wire length, particularly with respect to large-format cells. Additionally, including multiple anode tabs and cathode tabs may provide an additional path for monitoring the electrochemical cell separate from the current path of the system. Monitoring the voltage at various points throughout the cell or electrode can be an important aspect in constructing an energy storage system. Current cell algorithms assume that the electrochemical cell is essentially uniform and functions as a homogeneous entity. Identifying differences in voltage gradients or inflection points can help identify problematic cells or electrodes. Identifying these defective elements during production or even during operation can significantly limit the downtime of the energy storage system during repair or replacement.

[0009] The embodiments described herein can include algorithms that use sensors to detect cell-level faults, internal shorts, and other fault modes. Sensing can 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. The algorithms can then be used to diagnose the functional state of each cell within the system. In some cases, sensing can be achieved via a BMS, test system sensing, secondary sensing system, or any combination thereof. The safety system can include area temperature (hot spot), fire detection, smoke detection, hydrogen detection, carbon monoxide (CO) detection, carbon dioxide (CO2) detection, volatile organic compound (VOC) detection, or other detection methods for confirming that the system is not damaged or preventing damage to the system being formed, the battery, and the facility. The safety system can include a fire suppression system for preventing damage to the facility, an active ventilation system for preventing damage to the facility and personal injury, and a protection system for providing propagation protection between the cells, modules, and / or battery packs being formed.

[0010] 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 semi-solid electrodes. The semi-solid electrodes described herein can be made (i) thicker than conventional electrodes (e.g., greater than 100 μm, up to 2,000 μm or more) due to a reduction in the degree of bendability and an increase in conductivity of the semi-solid electrodes, (ii) with a higher loading of active material, and (iii) by a simplified manufacturing process that utilizes fewer devices. These relatively thick semi-solid electrodes reduce the volume, mass, and cost contribution of the inactive components to the active components, thereby enhancing the commercial attractiveness of the batteries made using the semi-solid electrodes. In some embodiments, the semi-solid electrodes described herein are binderless and / or do not use the binders used in conventional battery manufacturing. Instead, the volume of the electrode that is normally occupied by a binder in a conventional electrode is here occupied by the following. 1) The electrolyte. It has the effect of reducing the degree of bendability and increasing the total amount of salts available for ion diffusion, thereby counteracting the salt depletion effect characteristic of thick conventional electrodes when used at high rates. 2) The active material. It has the effect of increasing the charge capacity of the battery. Or 3) The conductive additive. It has the effect of increasing the electronic conductivity of the electrode, thereby counteracting the high internal impedance of thick conventional electrodes. Due to the reduction in the degree of bendability and the increase in electronic conductivity of the semi-solid electrodes described herein, excellent rate characteristics and charge capacity of the electrochemical cells formed from the semi-solid electrodes are obtained. Since the semi-solid electrodes described herein can be made substantially thicker than conventional electrodes, the ratio of the active material (i.e., the semi-solid cathode and / or anode) to the inactive material (i.e., the current collector and separator) can be made much higher in a battery formed from an electrochemical cell stack including the semi-solid electrodes compared to a similar battery formed from an electrochemical cell stack including conventional electrodes. As a result, the overall charge capacity and energy density of the batteries including the semi-solid electrodes described herein are substantially increased.

[0011] In some embodiments, the electrode materials described herein can be a flowable semi-solid or condensed liquid composition. In some embodiments, the electrode materials described herein can be binderless or substantially binder-free. The flowable semi-solid electrodes can include a suspension of electrochemically active materials (anode or cathode particles or particulate) and, optionally, an electron conductive material (e.g., carbon) in a non-aqueous liquid electrolyte. In other words, the active electrode particles and the conductive particles are co-suspended in the electrolyte to form a semi-solid electrode. Examples of battery architectures that utilize semi-solid suspensions are described in U.S. Patent Publication No. 2022 / 0238923, filed Jan. 21, 2022, titled “Production of Semi-Solid Electrodes Via Addition of Electrolyte to Mixture of Active Material, Conductive Material, and Electrolyte Solvent” (the “’923 publication”), and Provisional Patent Application No. 63 / 354,056, filed Jun. 21, 2022, titled “Electrochemical Cells with High-Viscosity Semi-solid Electrodes, and Methods of Making the Same” (the “’056 application”), the entire disclosures of which are incorporated herein by reference.

[0012] In some embodiments, the power management system described herein can include any of the aspects described in U.S. Patent No. 10,153,651, filed October 9, 2015, and entitled "Systems and Methods for Battery Charging" (the " '651 Patent"), the disclosure of which is hereby incorporated by reference in its entirety. In some embodiments, the battery management system described herein can include any of the aspects described in U.S. Patent Application No. 17 / 743,631, filed November 20, 2020, and entitled "Electrochemical Cells Connected in Series in a Single Pouch and Methods of Making the Same" (the " '631 Application"), the disclosure of which is hereby incorporated by reference in its entirety.

[0013] As used herein, 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 the term "material" is intended to mean one or more materials, or combinations thereof.

[0014] When used in connection with the terms "cylindrical", "linear", and / or other geometric relationships, the term "substantially" 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 linearity of that portion is desirable, but that some non-linearity may occur in a "substantially linear" portion. Such non-linearity can result from manufacturing tolerances, or other practical considerations (such as pressure or force applied to the support member, etc.). Thus, a geometric structure modified by the term "substantially" includes such geometric characteristics within a plus or minus 5% tolerance of the described geometric structure. For example, a "substantially linear" portion is a portion that defines an axis or centerline within plus or minus 5% of being linear.

[0015] As used herein, the terms "set" and "plurality" may refer to a single feature with a plurality of characteristics, or a plurality of parts. For example, when referring to a set of electrodes, the set of electrodes can be considered as one electrode with a plurality of parts, or the set of electrodes can be considered as a plurality of separate electrodes. Additionally, for example, when referring to a plurality of electrochemical cells, the plurality of electrochemical cells can be considered as a plurality of separate electrochemical cells, or one electrochemical cell with a plurality of parts. Thus, a set of parts or a plurality of parts may include a plurality of parts that are contiguous or discontinuous with each other. A plurality of particles or a plurality of materials can also be made from a plurality of articles that are separately produced and later joined to each other (e.g., by mixing, an adhesive, or any suitable method).

[0016] As used herein, the term "semi-solid" refers to a material that is a mixture of a liquid phase and a solid phase, such as, for example, a particle suspension, a slurry, a colloidal suspension, an emulsion, a gel, or a micelle.

[0017] As used herein, the terms "activated carbon network" and "networked carbon" relate to the general qualitative state of an electrode. For example, an electrode comprising an activated carbon network (or networked carbon) is one in which the carbon particles within the electrode assume individual particle forms and arrangements that facilitate electrical contact and electrical conductivity among the particles and through the thickness and length of the electrode. Conversely, the terms "non-activated carbon network" and "non-networked carbon" relate to an electrode that exists as individual particle islands or multi-particle agglomerate islands where the carbon particles may not be sufficiently connected to provide adequate electrical conduction through the electrode.

[0018] As used herein, the terms "energy density" and "volume energy density" refer to the amount of energy (e.g., MJ) stored within an electrochemical cell per unit volume (e.g., L) of the materials included for the operation of the electrochemical cell, such as electrodes, separators, electrolytes, and current collectors. Specifically, the materials used to package the electrochemical cell are excluded from the calculation of the volume energy density.

[0019] 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 (such as CoO, FeO), or titanium oxide.

[0020] 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, such as a silicon graphite layer.

[0021] As used herein, the term "solid high-capacity electrode layer" refers to an electrode layer having a single solid-phase high-capacity material, such as sputtered silicon, tin, tin alloys such as Sn-Fe, tin monoxide, silicon, silicon alloys such as Si-Co, silicon monoxide, aluminum, aluminum alloys, metal oxides (such as CoO, FeO), or titanium oxide.

[0022] FIG. 1 is a block diagram of an electrochemical cell stack 1000 according to one embodiment. As shown, the electrochemical cell stack 1000 includes electrochemical cells 100a, 100b, 100c (collectively referred to as electrochemical cell 100). However, any number of electrochemical cells may be included in the electrochemical cell stack. In some embodiments, the number of electrochemical cells in each stack 1000 may generally range from about 2 to about 100 (e.g., about 3, about 4, about 5, about 10, about 15, about 20, about 25, about 30, about 35, about 40, about 45, about 50, about 55, about 60, about 65, about 70, about 75, about 80, about 85, about 90, about 95, or about 100 electrochemical cells, including all ranges and values therebetween).

[0023] The electrochemical cell 100 includes anodes 110a, 110b, 110c (collectively referred to as anode 110) disposed on anode current collectors 120a, 120b, 120c (collectively referred to as anode current collector 120), cathodes 130a, 130b, 130c (collectively referred to as cathode 130) disposed on cathode current collectors 140a, 140b, 140c (collectively referred to as cathode current collector 140), and separators 150a, 150b, 150c (collectively referred to as separator 150) disposed between the anode 110 and the cathode 130. The anode current collector 120 includes anode tabs 122a, 122b, 122c (collectively referred to as anode tab 122). The cathode current collector 140 includes cathode tabs 142a, 142b, 142c (collectively referred to as cathode tab 142). Anode voltage measurement points VA a , VA b , VA cMeasure the voltage at the anode tabs 122a, 122b, and 122c, respectively. Cathode voltage measurement point VC a , VC b , VC c Measure the voltage at the cathode tabs 142a, 142b, and 142c, respectively. As shown, each of the electrochemical cells 100 is disposed within the casing 160. In some embodiments, each of the electrochemical cells 100 can be installed within an individual casing.

[0024] The electrochemical cell stack 1000 is provided to measure the voltage at each of the anode tabs 122 and each of the cathode tabs 142. Measuring the voltage difference from one anode to another or from one cathode to another can help identify the cell in question. For example, in a lithium-ion battery pack including a plurality of cells electrically in series, the cell voltages can be individually monitored to ensure that the limits set during charging or discharging are not exceeded. Due to variations between cells, the cells can also be periodically balanced to ensure that they do not exhibit a significant divergence in voltage that would impede overall performance. Balancing can include adding or removing charge from one of the electrochemical cells 100 to place it in series with other electrochemical cells 100 within the electrochemical cell stack 1000. In some embodiments, the anode tab 122 and / or the cathode tab 142 can penetrate the casing 160 so that the anode tab 122 and / or the cathode tab 142 can be externally monitored. In some embodiments, the anode tab 122 and / or the cathode tab 142 can be electrically connected to an external anode tab and / or an external cathode tab (not shown) so that the voltage can be externally monitored.

[0025] Figure 2 is a block diagram of an electrochemical cell 200 according to one embodiment. As shown, the electrochemical cell 200 includes an anode 210 disposed on an anode current collector 220, a cathode 230 disposed on a cathode current collector 240, and a separator 250 disposed between the anode 210 and the cathode 230. Anode tabs 222a, 222b, 222c (collectively referred to as anode tab 222) are coupled to or incorporated into the anode current collector 220, and cathode tabs 242a, 242b, 242c (collectively referred to as cathode tab 242) are coupled to or incorporated into the cathode current collector 240. In some embodiments, the anode 210, anode current collector 220, anode tab 222, cathode 230, cathode current collector 240, cathode tab 242, and separator 250 can be the same as or substantially similar to the anode 110, anode current collector 120, anode tab 122, cathode 130, cathode current collector 140, cathode tab 142, and separator 150 as described above with reference to FIG. 1. Accordingly, specific aspects of the anode 210, anode current collector 220, anode tab 222, cathode 230, cathode current collector 240, cathode tab 242, and separator 250 are not described in further detail herein.

[0026] The electrochemical cell 200 has an anode voltage measurement point VA positioned on the anode tab 222 a , VA b , VA c (collectively referred to as anode voltage measurement points VA), and a cathode voltage measurement point VC positioned on the cathode tab 242 a , VC b , VC c(collectively referred to as the cathode voltage measurement point VC). In other words, the voltage can be measured at multiple positions along the anode 210 and the cathode 230. As described above, the cell can be periodically balanced to ensure that the voltage does not vary significantly across the stack. In cells with large area electrodes, there may be a voltage gradient within the electrode that affects the voltage measured at any single reference point. The voltage gradient within the electrode may reduce the effectiveness of the balancing and health monitoring algorithms. The voltage gradient within the electrode may also cause a temperature gradient within the electrode and a reduction in cycle efficiency. Including a plurality of cathode voltage measurement points VA and a plurality of anode voltage measurement points VC for each cell 200 in the stack enables direct measurement of the voltage gradient within the electrode, rather than relying on the estimation of the voltage gradient within the electrode from the algorithm, thereby improving the accuracy of the balancing and monitoring methods.

[0027] As shown, the anode current collector 220 includes three anode tabs 222 and three voltage measurement points VA. In some embodiments, the anode current collector 220 can include at least about 2, at least about 3, at least about 4, at least about 5, at least about 6, at least about 7, at least about 8, at least about 9, at least about 10, at least about 15, at least about 20, at least about 25, at least about 30, at least about 35, at least about 40, at least about 45, at least about 50, at least about 55, at least about 60, at least about 65, at least about 70, at least about 75, at least about 80, at least about 85, at least about 90, or at least about 95 anode tabs 222 and / or voltage measurement points VA. In some embodiments, the anode current collector 220 can include about 100 or less, about 95 or less, about 90 or less, about 85 or less, about 80 or less, about 75 or less, about 70 or less, about 65 or less, about 60 or less, about 55 or less, about 50 or less, about 45 or less, about 40 or less, about 35 or less, about 30 or less, about 25 or less, about 20 or less, about 15 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, or about 3 or less anode tabs 222 and / or voltage measurement points VA. The above combinations of numbers of anode tabs 222 and voltage measurement points VA are also possible (e.g., at least about 2 and about 100 or less, or at least about 4 and about 30 or less), including all values and ranges therebetween. In some embodiments, the anode current collector 220 can include about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, about 10, about 15, about 20, about 25, about 30, about 35, about 40, about 45, about 50, about 55, about 60, about 65, about 70, about 75, about 80, about 85, about 90, about 95, or about 100 anode tabs 222 and / or voltage measurement points VA.

[0028] As shown, the cathode current collector 240 includes three cathode tabs 242 and three voltage measurement points VC. In some embodiments, the cathode current collector 240 can include at least about 2, at least about 3, at least about 4, at least about 5, at least about 6, at least about 7, at least about 8, at least about 9, at least about 10, at least about 15, at least about 20, at least about 25, at least about 30, at least about 35, at least about 40, at least about 45, at least about 50, at least about 55, at least about 60, at least about 65, at least about 70, at least about 75, at least about 80, at least about 85, at least about 90, or at least about 95 cathode tabs 242 and / or voltage measurement points VC. In some embodiments, the cathode current collector 240 can include about 100 or less, about 95 or less, about 90 or less, about 85 or less, about 80 or less, about 75 or less, about 70 or less, about 65 or less, about 60 or less, about 55 or less, about 50 or less, about 45 or less, about 40 or less, about 35 or less, about 30 or less, about 25 or less, about 20 or less, about 15 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, or about 2 or less cathode tabs 242 and / or voltage measurement points VC. The above combinations of the number of anode tabs 242 and voltage measurement points VC are also possible (e.g., at least about 2 to about 100 or less, or at least about 4 to about 30 or less), including all values and ranges therebetween. In some embodiments, the cathode current collector 240 can include about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, about 10, about 15, about 20, about 25, about 30, about 35, about 40, about 45, about 50, about 55, about 60, about 65, about 70, about 75, about 80, about 85, about 90, about 95, or about 100 cathode tabs 242 and / or voltage measurement points VC.

[0029] As shown, the voltage source is provided from above the electrochemical cell 200. In other words, the voltage source can be closer to the anode tab 222a than to the anode tab 222c. During discharge, the voltage of VC c > the voltage of VC b > the voltage of VC a During charging, the voltage of VC cThe voltage <VC b The voltage <VC a is the voltage. During charging, VA c The voltage <VC b The voltage <VA a is the voltage. During discharging, VA c The voltage >VA b The voltage >VA a is the voltage. The length of the electrochemical cell 200 extends along the y-axis direction as shown in FIG. 2. The "sensing voltage" can be defined as the difference between VC and VA at a reference point along the length (y-axis) of the electrochemical cell 200. The "sensing voltage" can be measured at various reference points along the length (y-axis) of the electrochemical cell 200 (for example, VA a -VC a or VA b -VC b ).

[0030] During or immediately after discharge, the sensed voltage is lower than the average cell voltage. During or immediately after charging, the sensed voltage is higher than the average cell voltage. This effect becomes stronger given any of the conditions of high charge or discharge rate, high surface area electrodes (as the point where the sensed voltage is measured gets further from the voltage source), low temperature charge or discharge, high resistance cell design (i.e., low power), and aged cells with increased internal resistance. The benefits of monitoring the sensed voltage are as follows: (1) enhanced healthy state monitoring, (2) elimination of the need to pause the balancing function to take voltage measurements, and (3) early detection of performance problems in the cell (e.g., non-uniform aging of electrodes or non-uniform temperature distribution across the electrode area). Evaluation of the voltage difference of the active material across the face of the electrochemical cell enables tracking of changes in the active material over time (e.g., increase in cell impedance, decrease in cell capacity, etc.). The plurality of anode tabs 222 and cathode tabs 242 enable these changes in the active material to be measured in real time. When attempting to detect a defective cell, measuring the sensed voltage from the tabs, which are also used to balance the electrochemical cell 200 or supply power to the electrochemical cell 200, is disadvantaged by the flow of current through the tabs and the presence of the active material in proximity to the tabs, which can adversely affect the measured values collected (e.g., cause a voltage offset in the measured values). The voltage offset occurs because the flow of current through the tab material generates an additional voltage drop and may have a polarization effect on the active material within the cathode. Measuring the sensed voltage from tabs where no current is flowing addresses this drawback by including the plurality of anode tabs 222 and cathode tabs 242.

[0031] Figure 3 shows an electrochemical cell 300 according to one embodiment. As shown, the electrochemical cell 300 includes an anode current collector 320 having anode tabs 322a, 322b, 322c, 322d, 322e (collectively referred to as anode tabs 322), and a cathode current collector 340 having cathode tabs 342a, 342b, 342c, 342d, 342e (collectively referred to as cathode tabs 342). The electrochemical cell 300 also includes an anode, a cathode, and a separator (not shown). In some embodiments, the anode current collector 320, the anode tabs 322, the cathode current collector 340, and the cathode tabs 342 can be the same as or substantially similar to the anode current collector 220, the anode tabs 222, the cathode current collector 240, and the cathode tabs 242 as described above with reference to FIG. 2. Accordingly, specific aspects of the anode current collector 320, the anode tabs 322, the cathode current collector 340, and the cathode tabs 342 are not described in further detail herein.

[0032] For clarity of structure, an axis is shown in FIG. 3. As shown, the anode current collector 320 has a length L a and a width W a As shown, the cathode current collector 340 has a length L c and a width W c The length L a and the length L c are defined as the distance that the anode current collector 320 extends along the y-axis and the distance that the cathode current collector 340 extends along the y-axis, respectively. The width W a and the width W c are defined as the distance that the anode current collector 320 extends along the x-axis and the distance that the cathode current collector 340 extends along the x-axis, respectively. The electrochemical cell 300 includes a proximal end along the y-axis. As shown, the anode tab 322a and the cathode tab 342a are located at the proximal end of the y-axis. The electrochemical cell 300 includes a distal end opposite the proximal end.

[0033] In some embodiments, L a and / or L ccan 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 a and / or L c can 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 to about 1 m or more, or at least about 3 cm to about 10 cm or less), including all values and ranges therebetween. In some embodiments, L a and / or L c 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.

[0034] In some embodiments, W a and / or W c 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. In some embodiments, W a and / or W ccan 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 and up to about 50 cm, or at least about 2 cm and up to about 10 cm), including all values and ranges therebetween. In some embodiments, W a and / or W c can 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.

[0035] As shown, the anode current collector 320 includes five anode tabs 322. In some embodiments, the anode current collector 320 can include at least about 2, at least about 3, at least about 4, at least about 5, at least about 6, at least about 7, at least about 8, at least about 9, at least about 10, at least about 15, at least about 20, at least about 25, at least about 30, at least about 35, at least about 40, at least about 45, at least about 50, at least about 55, at least about 60, at least about 65, at least about 70, at least about 75, at least about 80, at least about 85, at least about 90, or at least about 95 anode tabs 322. In some embodiments, the anode current collector 320 can include about 100 or less, about 95 or less, about 90 or less, about 85 or less, about 80 or less, about 75 or less, about 70 or less, about 65 or less, about 60 or less, about 55 or less, about 50 or less, about 45 or less, about 40 or less, about 35 or less, about 30 or less, about 25 or less, about 20 or less, about 15 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, or about 3 or less anode tabs 322. Combinations of the above numbers of anode tabs 322 are also possible (e.g., at least about 2 and up to about 100, or at least about 5 and up to about 50), including all values and ranges therebetween. In some embodiments, the anode current collector 320 can include about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, about 10, about 15, about 20, about 25, about 30, about 35, about 40, about 45, about 50, about 55, about 60, about 65, about 70, about 75, about 80, about 85, about 90, about 95, or about 100 anode tabs 322.

[0036] As shown, the cathode current collector 340 includes five cathode tabs 342. In some embodiments, the cathode current collector 340 can include at least about 2, at least about 3, at least about 4, at least about 5, at least about 6, at least about 7, at least about 8, at least about 9, at least about 10, at least about 15, at least about 20, at least about 25, at least about 30, at least about 35, at least about 40, at least about 45, at least about 50, at least about 55, at least about 60, at least about 65, at least about 70, at least about 75, at least about 80, at least about 85, at least about 90, or at least about 95 cathode tabs 342. In some embodiments, the cathode current collector 340 can include about 100 or less, about 95 or less, about 90 or less, about 85 or less, about 80 or less, about 75 or less, about 70 or less, about 65 or less, about 60 or less, about 55 or less, about 50 or less, about 45 or less, about 40 or less, about 35 or less, about 30 or less, about 25 or less, about 20 or less, about 15 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, or about 3 or less cathode tabs 342. Combinations of the above numbers of cathode tabs 342 are also possible (e.g., at least about 2 or more and about 100 or less, or at least about 5 or more and about 50 or less), including all values and ranges therebetween. In some embodiments, the cathode current collector 340 can include about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, about 10, about 15, about 20, about 25, about 30, about 35, about 40, about 45, about 50, about 55, about 60, about 65, about 70, about 75, about 80, about 85, about 90, about 95, or about 100 cathode tabs 342.

[0037] As shown, the cathode current collector 340 is W c along and has one cathode tab 342a that extends outwardly (e.g., in the positive y direction) from the proximal end of the electrochemical cell 300, and L c along and includes four cathode tabs 342b, 342c, 342d, 342e that extend outwardly (e.g., in the negative x direction) from the first horizontal side of the electrochemical cell 300. In some embodiments, the cathode current collector 340 is W ccan include a plurality of outwardly extending cathode tabs 342 along. As shown, the anode current collector 320 is located along W a and includes one anode tab 322a that extends outwardly (e.g., in the positive y direction) from the proximal end of the electrochemical cell 300, and L a and includes four anode tabs 322b, 322c, 322d, 322e that are located along and extend outwardly (e.g., in the positive x direction) from the second horizontal side of the electrochemical cell 300. In some embodiments, the anode current collector 320 can include a plurality of anode tabs 322 along W a that extend outwardly from the proximal end of the electrochemical cell 300.

[0038] In some embodiments, the distance between each of the cathode tabs 342a, 342b, 342c, 342d, 342e, and the distance between each of the anode tabs 322a, 322b, 322c, 322d, 322e can be at least about 0.5 cm, at least about 1 cm, at least about 1.5 cm, at least about 2 cm, at least about 2.5 cm, or at least about 3 cm. In some embodiments, the distance between each of the cathode tabs 342, and the distance between each of the anode tabs 322 can be about 5 cm or less, about 4.5 cm or less, about 4 cm or less, about 3.5 cm or less, about 3 cm or less, about 2.5 cm or less, about 2 cm or less, about 1.5 cm or less, about 1 cm or less. Combinations of the above distances are also possible, including all values and ranges therebetween.

[0039] In some embodiments, the cathode tabs 342 (e.g., cathode tabs 342b, 342c, 342d, 342e) extending from the same surface of the cathode current collector 340 can be equally spaced from each other. In some embodiments, the cathode tabs 342 extending from the same surface of the cathode current collector 340 can be unevenly spaced, or their spacing can be variable. In some embodiments, the anode tabs 322 (e.g., anode tabs 322b, 322c, 322d, 322e) extending from the same surface of the anode current collector 320 can be equally spaced from each other. In some embodiments, the anode tabs 322 extending from the same surface of the anode current collector 320 can be unevenly spaced, or their spacing can be variable.

[0040] In some embodiments, the anode tabs 322b, 322c, 322d, 322e can be aligned or substantially aligned with the cathode tabs 342b, 342c, 342d, 342e, respectively (i.e., along the y-axis). Any number of anode tabs 322 can be aligned with any number of cathode tabs 342. In other words, any number of anode tabs 322 can be in the same or substantially similar position along L a or L c relative to any number of cathode tabs 342. In some embodiments, any one of the anode tabs 322 can be within about 10%, about 9%, about 8%, about 7%, about 6%, about 5%, about 4%, about 3%, about 2%, or about 1% of alignment along the y-axis relative to any one of the cathode tabs 342.

[0041] The anode tabs 322 can provide a plurality of positions or reference points along the length L a of the anode current collector 320 to enable anode voltage measurements at the plurality of positions or reference points of the anode current collector 320. The cathode tabs 342 can be along the length L cProviding a plurality of positions or reference points along [it] may enable measurement of the cathode voltage at a plurality of positions of the cathode current collector 340. The sensed voltage (e.g., the difference between the cathode voltage and the anode voltage) may then be calculated at each of the plurality of reference points. In some embodiments, the electrochemical cell 300 has a width W of the anode current collector 320 a may include an anode tab 322 at a plurality of positions or reference points along [it]. In some embodiments, the electrochemical cell 300 has a width W of the cathode current collector 340 c may include a cathode tab 342 at a plurality of positions or reference points along [it]. The anode and / or cathode voltage is L a and W a The plurality of reference points at which measurements may be taken along both [of them] enables detection of the electrode internal gradient along both the length (y-direction) of the electrochemical cell 300 and the width (x-direction) of the electrochemical cell 300. In some embodiments, the anode tab 322a and the cathode tab 342a can be used to perform a balance adjustment function while simultaneously monitoring the cathode and anode voltages, thereby enabling monitoring of the electrochemical cell 300 without the need to temporarily stop the balance adjustment function.

[0042] Figure 4 shows an electrochemical cell 400 according to one embodiment. As shown, the electrochemical cell 400 includes an anode current collector 420 having anode tabs 422a, 422b, 422c, 422d (collectively referred to as anode tabs 422), and a cathode current collector 440 having cathode tabs 442a, 442b, 442c, 442d, 442e (collectively referred to as cathode tabs 442). The electrochemical cell 400 also includes an anode, a cathode, and a separator (not shown). The electrochemical cell 400 also includes a casing or housing 460 to which external anode tabs 423a, 423b, 423c, 423d (collectively referred to as external anode tabs 423) and external cathode tabs 443a, 443b, 443c, 444d (collectively referred to as external cathode tabs 443) are added. In some embodiments, the anode current collector 420, the anode tabs 422, the cathode current collector 440, and the cathode tabs 442 can be the same as or substantially similar to the anode current collector 320, the anode tabs 322, the cathode current collector 340, and the cathode 342 as described above with reference to FIG. 3. Accordingly, specific aspects of the anode current collector 420, the anode tabs 422, the cathode current collector 440, and the cathode tabs 442 are not described in further detail herein.

[0043] The anode tabs 422 are electrically coupled to the external anode tabs 423. The cathode tabs 442 are electrically coupled to the external cathode tabs 443. In some embodiments, the external anode tabs 423 and the external cathode tabs 443 can be integrated into the casing 460. In other words, the external anode tabs 423 and the external cathode tabs 443 can be part of the same piece of material as the casing 460. The external anode tabs 423 and the external cathode tabs 443 allow for connection of a voltage source or a voltage measurement device at various points along the anode and / or the cathode.

[0044] FIG. 5 is a schematic flowchart of a method 500 for monitoring the integrity of an electrochemical cell. Although described with respect to an electrochemical cell 200 including an anode tab 222, a cathode tab 242, an anode current collector 220, and a cathode current collector 240, an anode material 210, a cathode material 230, and a separator 250, the method 500 is equally applicable to any electrochemical cell including any anode tab, cathode tab, anode current collector, cathode current collector, anode material, cathode material, separator, and / or any other component described herein. All such variations should be considered to be within the scope of the present disclosure.

[0045] In step 502, the method 500 optionally provides an electrochemical cell 200 including an anode material 210 coupled to an anode current collector 220 having a plurality of anode tabs 222, a cathode material 230 coupled to a cathode current collector 240 having a plurality of cathode tabs 242, and a separator 250 disposed between the anode material 210 and the cathode material 230. In step 504, a first anode voltage can be measured at a first anode tab from the plurality of anode tabs 222, and a second anode voltage can be measured at a second anode tab from the plurality of anode tabs 222. In some embodiments, the first anode tab and the second anode tab from the anode tabs 222 can be located on the same horizontal side of the electrochemical cell 200, and the first anode tab is closer to the proximal end of the electrochemical cell 200 than the second anode tab. In step 506, a first cathode voltage can be measured at a first cathode tab from the plurality of cathode tabs 242, and a second cathode voltage can be measured at a second cathode tab from the plurality of cathode tabs 242. In some embodiments, the first cathode tab and the second cathode tab from the cathode tabs 242 can be located on the same horizontal side of the electrochemical cell 200, and the first cathode tab is closer to the proximal end of the electrochemical cell 200 than the second cathode tab.

[0046] In step 508, method 500 includes calculating a first sensed voltage that is the difference between a first cathode voltage and a first anode voltage. Optionally, in step 510, a second sensed voltage that is the difference between a second cathode voltage and a second anode voltage may be calculated. In step 512, method 500 may optionally include calculating the difference between the first sensed voltage and the second sensed voltage, thereby enabling detection and / or quantification of an in-electrode gradient along the length (e.g., y-direction) of the electrochemical cell 200. In some embodiments, method 500 may optionally include calculating a third sensed voltage that is the difference between a third cathode voltage measured at a third cathode tab located at the proximal end of the electrochemical cell 200 and a third anode voltage measured at a third anode tab at the proximal end of the electrochemical cell 200. A third sensed voltage that enables detection and / or quantification of an in-electrode gradient along the width (x-direction) of the electrochemical cell 200. In some embodiments, method 500 may include adjusting the balance of the electrochemical cell 200 via the third anode tab and the third cathode tab. For example, charge can be added or removed from the electrochemical cell 200 via the third anode tab and / or the third cathode tab. In some embodiments, any one of the anode tabs 222 and any one of the cathode tabs 244 may be used to adjust the balance of the electrochemical cell 200. In some embodiments, the electrochemical cell 200 may be disposed within a casing. In some embodiments, method 500 may include measuring the anode voltage and the cathode voltage via a plurality of external anode tabs and a plurality of external cathode tabs, respectively, such that the anode voltage and the cathode voltage are measured outside of the casing.

[0047] Various concepts may be embodied in one or more ways, and at least one example of this is provided. The acts performed as part of the method may be ordered in any suitable manner. Thus, even though in the exemplary embodiments they are shown as sequential operations, embodiments may be constructed in which some operations are performed simultaneously, including operations performed in a different order than that shown. Stated another way, 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, in parallel, in series, simultaneously, and / or synchronously in a manner consistent with this disclosure. Accordingly, some of these features may be mutually contradictory in that they cannot coexist in a single embodiment at the same time. Similarly, some features may be applicable to one aspect of the invention and not to others.

[0048] In addition, the present disclosure may include other innovations not presently described. The applicant retains all rights in such inventions, including the right to practice such inventions and to file additional applications, continuations, continuation-in-parts, divisions, and / or the like. Thus, 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 as defined by the embodiments or limitations of equivalents of the embodiments. Depending on the particular desires and / or characteristics of individual and / or corporate users, database configurations and / or relational models, data types, data transmission and / or network frameworks, syntactic structures, etc., the various embodiments of the technology disclosed herein may be implemented in ways that allow for a great deal of flexibility and customization, as described herein.

[0049] All definitions as defined and used herein are to be understood as controlling dictionary definitions, definitions in incorporated documents by reference, and / or ordinary meanings of defined terms.

[0050] As used herein, in certain embodiments, when preceding a numerical value, the terms "about" or "approximately" indicate a range of plus or minus 10% of the value. When a range of values is provided, unless the context clearly indicates otherwise, each intervening value between the lower and upper limits of that range, to one-tenth of the unit of the lower limit, and any other stated value or intervening value within the stated range is to be understood as being included within the present disclosure. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges and are subject to the limits specifically excluded from the stated range, and are also included within the present disclosure. When the stated range includes one or both of the limits, ranges excluding one or both of those included limits are also included in the present disclosure.

[0051] As used in this specification and the embodiments of this application, the phrase "and / or" should be understood to mean "either or both" of the elements so conjunctively connected, i.e., elements that may exist conjunctively in some cases and disjunctively in other cases. The plurality of elements listed with "and / or" should be construed in the same manner, i.e., as "one or more" of the elements so combined. Other elements may optionally exist, whether or not they are related to the specifically identified elements, other than those specifically identified by the "and / or" clause. Thus, by way of non-limiting example, 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), and in yet another embodiment to both A and B (optionally including other elements).

[0052] As used in this specification and the embodiments of this application, "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" is to be interpreted inclusively, that is, including at least one of the number of elements or the list, but more than one, and optionally, additional unlisted items. For example, only terms that are explicitly indicated to the contrary, such as "only one of" or "exactly one of", or when used in an embodiment, "consisting of", will refer to the inclusion of exactly one element of the number of elements or the list. In general, as used in this specification, the term "or" should be interpreted as indicating an exclusive alternative (i.e., "one or the other, but not both") only when preceded by an exclusive term, such as "either", "one of", "only one of", or "exactly one of". "Consisting essentially of" shall have the ordinary meaning used in the field of patent law when used in an embodiment.

[0053] As used in this specification and the embodiments of this application, the phrase "at least one" should be understood to mean at least one element selected from any one or more of the elements in a list of one or more elements, but does not necessarily include at least one of every element specifically listed in the list of elements, and does not necessarily exclude any combination of the elements in the list of elements. This definition also allows for the optional presence of elements other than those specifically identified in the list of elements referred to by the phrase "at least one", whether or not such other elements are related to the specifically identified elements. Thus, by way of 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, in one embodiment, include at least one, optionally two or more, of A and no B (and optionally include elements other than B); in another embodiment, include at least one, optionally two or more, of B and no A (and optionally include elements other than A); and in yet another embodiment, include at least one, optionally two or more, of A and at least one, optionally two or more, of B (and optionally include other elements), and so on.

[0054] In embodiments, as well as in the above specification, all transitional phrases such as "comprising", "including", "carrying", "having", "containing", "involving", "holding", "consisting of", etc. are to be understood as open-ended, i.e., meaning "including but not limited to". As described in section 2111.03 of the United States Patent and Trademark Office's Manual of Patent Examining Procedure (USPTO Patent Examination Handbook), only the transitional phrases "consisting of" and "consisting essentially of" must be closed or semi-closed transitional phrases, respectively.

[0055] 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 are intended to be illustrative rather than limiting, as described herein. Various changes may be made without departing from the spirit and scope of the present disclosure. If the methods and steps described above indicate certain events occurring in a particular order, those skilled in the art who benefit from the present disclosure may change the order of certain steps, and will recognize that such changes follow the variations of the invention. Additionally, some steps may not only be executed sequentially as described above, but may also be executed simultaneously in parallel processing if possible. Although the embodiments have been illustrated and described in detail, it is understood that various modifications in form and detail may be made.

Claims

1. A method of operating an electrochemical cell included in an electrochemical cell stack having a plurality of electrochemical cells, wherein each of the electrochemical cells included in the electrochemical cell stack includes an anode material coupled to an anode current collector having a plurality of anode tabs, a cathode material coupled to a cathode current collector having a plurality of cathode tabs, and a separator disposed between the anode material and the cathode material, the method comprising: measuring an anode voltage difference between a first anode tab from the plurality of anode tabs of the electrochemical cell and a second anode tab from the plurality of anode tabs of the electrochemical cell; measuring a cathode voltage difference between a first cathode tab from the plurality of cathode tabs of the electrochemical cell and a second cathode tab from the plurality of cathode tabs of the electrochemical cell; adjusting the balance of the electrochemical cell relative to other electrochemical cells included in the electrochemical cell stack based at least on the values of the anode voltage difference and the cathode voltage difference.

2. The method of claim 1, wherein the first cathode tab and the first anode tab are each located at a proximal end of the electrochemical cell.

3. The method of claim 2, wherein a distance between the first anode tab and the second anode tab is within about 5% of the distance between the first cathode tab and the second cathode tab.

4. The method of claim 2, wherein the second cathode tab extends outwardly from a first horizontal side of the electrochemical cell, the second anode tab extends outwardly from a second horizontal side of the electrochemical cell, and the second horizontal side is opposite the first horizontal side.

5. The method of claim 1, wherein the cathode current collector and the anode current collector each have a length of at least about 5 cm.

6. The method of claim 1, wherein the electrochemical cell is disposed within a casing, the casing including a plurality of external anode tabs and a plurality of external cathode tabs such that the anode voltage difference and the cathode voltage difference are measured from outside the casing.

7. A method for monitoring the integrity of an electrochemical cell, wherein the electrochemical cell includes an anode material coupled to an anode current collector having a plurality of anode tabs, a cathode material coupled to a cathode current collector having a plurality of cathode tabs, and a separator disposed between the anode material and the cathode material, and the method includes measuring a first anode voltage at a first anode tab from the plurality of anode tabs and a second anode voltage at a second anode tab from the plurality of anode tabs; measuring a first cathode voltage at a first cathode tab from the plurality of cathode tabs and a second cathode voltage at a second cathode tab from the plurality of cathode tabs; calculating a first sensed voltage that is a difference between the first cathode voltage and the first anode voltage. A method comprising.

8. The method according to claim 7, further comprising calculating a second sensed voltage that is a difference between the second cathode voltage and the second anode voltage.

9. The method according to claim 8, further comprising calculating a difference between the first sensed voltage and the second sensed voltage.

10. The method according to claim 7, wherein the first cathode tab and the first anode tab extend outwardly from a proximal end of the electrochemical cell.

11. The method according to claim 10, wherein a distance between the first anode tab and the second anode tab is within about 5% of the distance between the first cathode tab and the second cathode tab.

12. The method according to claim 10, wherein the second cathode tab extends outwardly from a first horizontal side of the electrochemical cell, the second anode tab extends outwardly from a second horizontal side of the electrochemical cell, and the second horizontal side is on the opposite side of the first horizontal side.

13. The method according to claim 7, wherein the cathode current collector and the anode current collector each have a length of at least about 5 cm.

14. The method according to claim 7, wherein the cathode current collector and the anode current collector each have a width of at least about 5 mm.

15. The electrochemical cell is disposed within a casing, the casing including a plurality of external anode and a plurality of external cathode tabs such that the first anode voltage, the second anode voltage, the first cathode voltage, and the second cathode voltage are measured from outside the casing, the method of claim 7.

16. An electrochemical cell, comprising: an anode material coupled to an anode current collector; a cathode material coupled to a cathode current collector; a separator disposed between the anode material and the cathode material; a plurality of anode tabs electrically connected to the anode current collector such that a first anode voltage can be measured at a first anode tab of the plurality of anode tabs and a second anode voltage can be measured at a second anode tab of the plurality of anode tabs; a plurality of cathode tabs electrically connected to the cathode current collector such that a first cathode voltage can be measured at a first cathode tab of the plurality of cathode tabs and a second cathode voltage can be measured at a second cathode tab of the plurality of cathode tabs.

17. The electrochemical cell of claim 16, wherein the first cathode tab and the first anode tab extend outwardly from a proximal end of the electrochemical cell.

18. The electrochemical cell of claim 17, wherein the plurality of cathode tabs excluding the first cathode tab extend outwardly from a first horizontal side of the electrochemical cell, and the plurality of anode tabs excluding the first anode tab extend outwardly from a second horizontal side of the electrochemical cell, the second horizontal side being opposite the first horizontal side.

19. The electrochemical cell of claim 18, wherein a distance between the first anode tab and the second anode tab is within about 5% of a distance between the first cathode tab and the second cathode tab.

20. The electrochemical cell of claim 16, wherein a distance between each of the anode tabs is in a range of about 1 cm to about 3 cm, and a distance between each of the cathode tabs is in a range of about 1 cm to about 3 cm.

21. The electrochemical cell of claim 16, wherein the cathode current collector and the anode current collector each have a length of at least about 5 cm.

22. The electrochemical cell according to claim 16, wherein the cathode current collector and the anode current collector each have a width of at least about 5 mm. **Claim 23** The electrochemical cell according to claim 17, wherein the electrochemical cell is disposed within a casing, the casing including a plurality of external anode tabs and a plurality of external cathode tabs such that the first anode voltage, the second anode voltage, the first cathode voltage, and the second cathode voltage can be measured from outside the casing. **Claim 24** The electrochemical cell according to claim 16, wherein a first voltage gradient is measurable along the width of the electrochemical cell and a second voltage gradient is measurable along the length of the electrochemical cell.

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