System and method for evaluating a reference electrode assembly of an electrochemical cell

Abstract

Systems and methods for evaluating a reference electrode assembly of an electrochemical cell are disclosed. A system for evaluating a characteristic of a reference electrode assembly of an electrochemical cell that cycles lithium ions includes a controller and a test cell assembly. The test cell assembly includes a metal can electrically connected to the controller and a test cell disposed within the metal can. The test cell includes a lithium metal layer and a separator assembly. The separator assembly includes a separator layer, a current collector layer deposited on the separator layer, and optionally an electroactive layer deposited on the separator layer such that the electroactive layer at least partially overlaps the current collector layer. The current collector layer is in direct physical contact with the electroactive layer and is electrically insulated from the lithium metal layer by the separator layer.

Description

Technical Field

[0001] This invention discloses a system for evaluating the characteristics of the current collector layer of a reference electrode assembly for a cyclic lithium-ion electrochemical battery and a system for evaluating the characteristics of a reference electrode assembly for a cyclic lithium-ion electrochemical battery. Background Technology

[0002] This section provides background information in connection with this disclosure, which is not necessarily prior art.

[0003] This disclosure generally relates to reference electrode assemblies, and more specifically to systems and methods for evaluating reference electrode assemblies for electrochemical cells including a working electrode, a counter electrode, and a reference electrode.

[0004] Reference electrode assemblies can be used in electrochemical cells for cycling lithium-ion batteries to monitor the individual potentials of the negative and / or positive electrodes of the electrochemical cell during cycling. Summary of the Invention

[0005] This section provides a general overview of this disclosure, rather than a full disclosure of its entire scope or all its features.

[0006] This disclosure relates to a system for evaluating the characteristics of a current collector layer in a reference electrode assembly of a cyclic lithium-ion electrochemical battery. The system includes a controller and a test battery assembly. The test battery assembly includes a first metal casing and a test battery disposed inside the first metal casing. The first metal casing includes a top and a bottom, which together define the interior of the first metal casing. The top of the first metal casing is electrically connected to the controller via a first electrical connector, and the bottom of the first metal casing is electrically connected to the controller via a second electrical connector. The test battery includes a first electroactive layer, a first lithium metal layer, and a separator assembly disposed between the first electroactive layer and the first lithium metal layer. The separator assembly includes a first separator layer having a first main surface and a current collector layer deposited on the first main surface of the first separator layer. The current collector layer is electrically insulated from the lithium metal layer through the first separator layer. The current collector layer is in direct physical contact with the first electroactive layer. The first lithium metal layer is electrically connected to the top of the first metal casing, and the first electroactive layer is electrically connected to the bottom of the first metal casing.

[0007] The test battery assembly may also include a metal spacer and a biasing member disposed between the test battery and the top of the first metal casing.

[0008] The top and bottom of the first metal casing can be electrically insulated from each other by gaskets.

[0009] The controller can be configured to generate a test battery cyclic voltammetry diagram by applying a potential between a first electroactive layer and a first lithium metal layer, cycling the applied potential between an initial potential and a set potential, and measuring the current at the first electroactive layer while the applied potential is cycling between the initial potential and the set potential.

[0010] The controller can be configured to provide an indicator of at least one of the following in the environment of the test battery: ion permeability of the current collector layer, compatibility between the current collector layer and the first electroactive layer, or electrochemical stability of the current collector layer.

[0011] The system may also include a control battery assembly. The control battery assembly may include a second metal casing and a control battery disposed within the second metal casing. The second metal casing may include a top and a bottom, which together define the interior of the second metal casing. The top of the second metal casing may be electrically connected to the controller via a third electrical connector, and the bottom of the second metal casing may be electrically connected to the controller via a fourth electrical connector. The control battery may include a second electroactive layer, a second lithium metal layer, and a second insulating layer, the second insulating layer being disposed between the second electroactive layer and the second lithium metal layer and in direct physical contact with the second electroactive layer and the second lithium metal layer. The second lithium metal layer may be electrically connected to the top of the second metal casing, and the second electroactive layer may be electrically connected to the bottom of the second metal casing.

[0012] The controller can be configured to generate a reference battery cyclic voltammetry by applying a potential between the second electroactive layer and the second lithium metal layer, cycling the applied potential between an initial potential and a set potential, and measuring the current at the second electroactive layer while the applied potential is cycling between the initial potential and the set potential.

[0013] A method for evaluating the characteristics of a current collector layer is disclosed. In the method, an electric potential is applied between a first electroactive layer and a first lithium metal layer. The potential can cycle between an initial potential and a set potential. While the potential cycles between the initial potential and the set potential, the current at the first electroactive layer can be measured. The potential of the first electroactive layer can be calculated. A test cell cyclic voltammogram of the current at the first electroactive layer relative to the potential of the first electroactive layer can be generated. The test cell cyclic voltammogram can be compared with a control cell cyclic voltammogram to obtain an index of at least one of the following in the test cell environment: ion permeability of the current collector layer, compatibility of the current collector layer with the first electroactive layer, or electrochemical stability of the current collector layer.

[0014] A system for evaluating the characteristics of a reference electrode assembly for a cycled lithium-ion electrochemical battery is disclosed. The system includes a controller and a test battery assembly. The test battery assembly includes a first metal casing and a test battery disposed inside the first metal casing. The first metal casing includes a top and a bottom, which together define the interior of the first metal casing. The top of the first metal casing is electrically connected to the controller via a first electrical connector, and the bottom of the first metal casing is electrically connected to the controller via a second electrical connector. The test battery includes a first lithium metal layer, an electrically insulating layer, and a separator assembly disposed between the first lithium metal layer and the electrically insulating layer. The separator assembly includes a first separator layer having a first main surface, a current collector layer deposited on the first main surface of the first separator layer, and a first electroactive layer deposited on the first main surface of the first separator layer, such that the first electroactive layer at least partially overlaps the current collector layer. The current collector layer is in direct physical contact with the first electroactive layer and is electrically insulated from the lithium metal layer through the first separator layer. The insulating assembly extends beyond the outer periphery of the electrical insulation layer, such that the central region of the first electrically active layer is physically separated from the bottom of the first metal shell through the electrical insulation layer, and the outer periphery of the first electrically active layer is in direct physical contact with the bottom of the first metal shell.

[0015] The first lithium metal layer can be electrically bonded to the top of the first metal shell, and the first electroactive layer can be electrically bonded to the bottom of the first metal shell.

[0016] An electrical insulating layer may be disposed on the bottom of the first metal casing, and an isolation assembly may be disposed on the bottom of the first metal casing, above the electrical insulating layer, such that during the cycling of the test battery, electrons flow through the central region of the first electroactive layer in a planar direction and through the peripheral region of the first electroactive layer in a lateral direction.

[0017] The controller can be configured to generate a test battery cyclic voltammetry diagram by applying a potential between a first electroactive layer and a first lithium metal layer, cycling the applied potential between an initial potential and a set potential, and measuring the current at the first electroactive layer while the applied potential is cycling between the initial potential and the set potential.

[0018] The controller can be configured to provide an indicator of at least one of the electrochemical performance or electrochemical stability of the separator assembly in the environment of the test battery.

[0019] The system may also include a control battery assembly. The control battery assembly may include a second metal casing and a control battery disposed within the interior of the second metal casing. The second metal casing may include a top and a bottom that together define the interior of the second metal casing. The top of the second metal casing may be electrically connected to a controller via a third electrical connector, and the bottom of the second metal casing may be electrically connected to the controller via a fourth electrical connector. The control battery may include a second lithium metal layer, a second electroactive layer disposed on a current collector foil, and a second insulating layer disposed between the second lithium metal layer and the second electroactive layer. The second lithium metal layer may be electrically connected to the top of the second metal casing, and the second electroactive layer may be electrically connected to the bottom of the second metal casing via the current collector foil.

[0020] The current collector foil can make physical and electrical contact with the bottom of the second metal shell.

[0021] A method for evaluating the characteristics of a separator assembly is disclosed. The method may include: applying a potential between a first electroactive layer and a first lithium metal layer, cycling the potential between an initial potential and a set potential; measuring the current at the first electroactive layer while the potential cycles between the initial and set potentials; calculating the potential of the first electroactive layer; generating a test battery cyclic voltammogram of the current at the first electroactive layer relative to the potential of the first electroactive layer; and comparing the test battery cyclic voltammogram with a control battery cyclic voltammogram to obtain an index of at least one of the electrochemical performance or electrochemical stability of the separator assembly in a test battery environment.

[0022] The method may also include: comparing the test battery cyclic voltammetry diagram with the control battery cyclic voltammetry diagram to determine whether the voltage peak described in the test battery cyclic voltammetry diagram is aligned with the corresponding voltage peak described in the control battery cyclic voltammetry diagram.

[0023] The present invention discloses the following embodiments:

[0024] Option 1. A system for evaluating the characteristics of a current collector layer in a reference electrode assembly for a cyclic lithium-ion electrochemical cell, the system comprising:

[0025] Controller; and

[0026] A test battery assembly includes:

[0027] A first metal housing, including a top and a bottom, together defining the interior of the first metal housing, wherein the top of the first metal housing is electrically connected to the controller via a first electrical connector, and the bottom of the first metal housing is electrically connected to the controller via a second electrical connector.

[0028] A test battery disposed inside the first metal casing includes a first electroactive layer, a first lithium metal layer, and a separator assembly disposed between the first electroactive layer and the first lithium metal layer. The separator assembly includes a first separator layer having a first main surface and a current collector layer deposited on the first main surface of the first separator layer. The current collector layer is electrically insulated from the lithium metal layer through the first separator layer, and the current collector layer is in direct physical contact with the first electroactive layer.

[0029] The first lithium metal layer is electrically connected to the top of the first metal shell, and the first electroactive layer is electrically connected to the bottom of the first metal shell.

[0030] Option 2. According to the system of embodiment 1, the test battery assembly further includes a metal spacer and a biasing member disposed between the test battery and the top of the first metal casing.

[0031] Option 3. The system according to embodiment 1, wherein the top and bottom of the first metal shell are electrically insulated from each other by a gasket.

[0032] Option 4. The system according to embodiment 1, wherein the controller is configured to generate a test battery cyclic voltammetry diagram by applying a potential between the first electroactive layer and the first lithium metal layer, cycling the applied potential between an initial potential and a set potential, and measuring the current at the first electroactive layer while the applied potential cycles between the initial potential and the set potential.

[0033] Option 5. The system according to embodiment 4, wherein the controller is configured to provide an indicator of at least one of the following in the environment of the test battery: the ion permeability of the current collector layer, the compatibility of the current collector layer with the first electroactive layer, or the electrochemical stability of the current collector layer.

[0034] Option 6. The system according to Implementation Scheme 1 further includes:

[0035] A comparative battery assembly includes:

[0036] A second metal housing, comprising a top and a bottom that together define the interior of the second metal housing, wherein the top of the second metal housing is electrically connected to the controller via a third electrical connector, and the bottom of the second metal housing is electrically connected to the controller via a fourth electrical connector; and

[0037] A control battery disposed inside the second metal casing, the control battery comprising a second electroactive layer, a second lithium metal layer, and a second insulating layer disposed between the second electroactive layer and the second lithium metal layer and in direct physical contact with the second electroactive layer and the second lithium metal layer.

[0038] The second lithium metal layer is electrically connected to the top of the second metal shell, and the second electroactive layer is electrically connected to the bottom of the second metal shell.

[0039] Option 7. The system according to embodiment 6, wherein the controller is configured to generate a reference battery cyclic voltammetry by applying a potential between the second electroactive layer and the second lithium metal layer, cycling the applied potential between an initial potential and a set potential, and measuring the current at the second electroactive layer while the applied potential cycles between the initial potential and the set potential.

[0040] Option 8. A method for evaluating the characteristics of the current collector layer according to embodiment 1, the method comprising:

[0041] An electric potential is applied between the first electroactive layer and the first lithium metal layer;

[0042] The potential is cyclical between the initial potential and the set potential;

[0043] As the potential cycles between the initial potential and the set potential, the current at the first electroactive layer is measured.

[0044] Calculate the potential of the first electroactive layer;

[0045] Generate a test cell cyclic voltammogram of the current at the first electroactive layer relative to the potential of the first electroactive layer; and

[0046] The cyclic voltammogram of the test battery is compared with that of the control battery to obtain an indicator of at least one of the following: the ion permeability of the current collector layer in the environment of the test battery, the compatibility of the current collector layer with the first electroactive layer, or the electrochemical stability of the current collector layer.

[0047] Option 9. A system for evaluating the characteristics of a reference electrode assembly for a cyclic lithium-ion electrochemical cell, the system comprising:

[0048] Controller; and

[0049] Test battery assemblies, including:

[0050] A first metal housing, comprising a top and a bottom that together define an interior of the first metal housing, wherein the top of the first metal housing is electrically connected to the controller via a first electrical connector, and the bottom of the first metal housing is electrically connected to the controller via a second electrical connector; and

[0051] A test battery disposed inside the first metal casing, the test battery comprising a first lithium metal layer, an electrically insulating layer, and a separator assembly disposed between the first lithium metal layer and the electrically insulating layer, the separator assembly comprising a first separator layer having a first main surface, a current collector layer deposited on the first main surface of the first separator layer, and a first electroactive layer deposited on the first main surface of the first separator layer, such that the first electroactive layer at least partially overlaps with the current collector layer.

[0052] The current collector layer is in direct physical contact with the first electroactive layer and is electrically insulated from the lithium metal layer through the first insulating layer.

[0053] The isolation assembly extends beyond the outer periphery of the electrical insulation layer, such that the central region of the first electroactive layer is physically separated from the bottom of the first metal shell through the electrical insulation layer, and the outer periphery of the first electroactive layer is in direct physical contact with the bottom of the first metal shell.

[0054] Option 10. The system according to embodiment 9, wherein the first lithium metal layer is electrically connected to the top of the first metal shell, and the first electroactive layer is electrically connected to the bottom of the first metal shell.

[0055] Option 11. The system according to embodiment 9, wherein the electrical insulating layer is disposed on the bottom of the first metal casing, and the separator assembly is disposed on the bottom of the first metal casing, above the electrical insulating layer, such that during the cycling of the test battery, electrons flow through the central region of the first electroactive layer in a planar direction and through the peripheral region of the first electroactive layer in a lateral direction.

[0056] Option 12. The system according to embodiment 9, wherein the controller is configured to generate a test battery cyclic voltammetry diagram by applying a potential between a first electroactive layer and a first lithium metal layer, cycling the applied potential between an initial potential and a set potential, and measuring the current at the first electroactive layer while the applied potential is cycling between the initial potential and the set potential.

[0057] Option 13. The system according to embodiment 12, wherein the controller is configured to provide an indicator of at least one of the electrochemical performance of the separator assembly or the electrochemical stability of the separator assembly in the environment of the test battery.

[0058] Option 14. The system according to embodiment 9 further includes:

[0059] Compared to battery assemblies, including:

[0060] A second metal housing, comprising a top and a bottom that together define the interior of the second metal housing, wherein the top of the second metal housing is electrically connected to the controller via a third electrical connector, and the bottom of the second metal housing is electrically connected to the controller via a fourth electrical connector; and

[0061] A control battery disposed inside the second metal casing, the control battery comprising a second lithium metal layer, a second electroactive layer disposed on a current collector foil, and a second insulating layer disposed between the second lithium metal layer and the second electroactive layer.

[0062] The second lithium metal layer is electrically connected to the top of the second metal shell, and the second electroactive layer is electrically connected to the bottom of the second metal shell via the current collector foil.

[0063] Option 15. The system according to embodiment 14, wherein the current collector foil is in physical and electrical contact with the bottom of the second metal shell.

[0064] Option 16. A method for evaluating the characteristics of the spacer assembly described in embodiment 9, the method comprising:

[0065] An electric potential is applied between the first electroactive layer and the first lithium metal layer;

[0066] The potential is cyclical between the initial potential and the set potential;

[0067] As the potential cycles between the initial potential and the set potential, the current at the first electroactive layer is measured.

[0068] Calculate the potential of the first electroactive layer;

[0069] Generate a test cell cyclic voltammogram of the current at the first electroactive layer relative to the potential of the first electroactive layer; and

[0070] The cyclic voltammogram of the test battery is compared with that of a control battery to obtain an indicator of at least one of the electrochemical performance or electrochemical stability of the separator assembly in the environment of the test battery.

[0071] Option 17. The method according to implementation scheme 16 further includes:

[0072] The test battery cyclic voltammogram is compared with the control battery cyclic voltammogram to determine whether the voltage peak described in the test battery cyclic voltammogram aligns with the corresponding voltage peak described in the control battery cyclic voltammogram.

[0073] Further applications will become apparent from the description provided herein. The descriptions and specific examples in this invention are intended for illustrative purposes only and are not intended to limit the scope of this disclosure. Attached Figure Description

[0074] The accompanying drawings described herein are for illustrative purposes only, for the purposes of selecting embodiments and not all possible implementations, and are not intended to limit the scope of this disclosure.

[0075] Figure 1 This is a perspective view of a cyclic lithium-ion electrochemical battery. The electrochemical battery includes a positive electrode, a negative electrode, a separator component disposed between the positive electrode and the negative electrode, and a reference electrode assembly disposed between the negative electrode and the separator component. The reference electrode assembly includes a separator layer, a reference electrode current collector layer, and an electroactive reference electrode layer.

[0076] Figure 2 and 3 It is used for evaluation and proposal. Figure 1 A schematic cross-sectional view of the current collector layer of the reference electrode assembly, the system including a controller and a test cell assembly, the test cell assembly including a dual-electrode electrochemical test cell containing the proposed current collector layer.

[0077] Figure 4 yes Figure 2 and 3 Cyclic voltammograms of current (I) versus potential (V) of a two-electrode electrochemical test cell.

[0078] Figure 5 This is a cyclic voltammogram of current (I) versus potential (V) for a two-electrode electrochemical control cell.

[0079] Figure 6 and 7 It is used to evaluate the proposed use Figure 1 A schematic cross-sectional view of a system for the characteristics of a reference electrode assembly in an electrochemical cell. The system includes a controller and a test cell assembly, which comprises a two-electrode electrochemical test cell containing a separator assembly.

[0080] Figure 8 Is with Figure 6 and 7 A schematic cross-sectional view of a control battery assembly with electrical connections to the controller, the control battery assembly including a dual-electrode electrochemical control battery.

[0081] Figure 9 Described Figure 6 and 7 Dual-electrode electrochemical test cell and Figure 8 Cyclic voltammogram of current (I) versus potential (V) for a two-electrode electrochemical control cell.

[0082] In the several views of the accompanying drawings, the corresponding reference numerals indicate the corresponding parts. Detailed Implementation Plan

[0083] Exemplary embodiments are provided to make this disclosure complete and to fully communicate its scope to those skilled in the art. Numerous specific details, such as examples of specific components, parts, apparatuses, and methods, are set forth to provide a full understanding of embodiments of this disclosure. It will be apparent to those skilled in the art that specific details are not required, that exemplary embodiments may be presented in many different forms, and that none of them should be construed as limiting the scope of this disclosure. In some exemplary embodiments, well-known methods, well-known apparatus structures, and well-known techniques are not described in detail.

[0084] The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” as used herein are intended to include the plural forms as well. The terms “comprising,” “including,” “covering,” and “having” are interchangeable and thus specify the presence of the stated features, elements, compositions, steps, integers, operations, and / or components, but do not preclude the presence or inclusion of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Although the open-ended terms “comprising,” “covering,” “including,” and “having” should be understood as non-limiting terms used to describe and claim the various embodiments described herein, in some respects these terms may be understood alternatively to more restrictive and limiting terms such as “consisting of” or “substantially consisting of.” Therefore, for any given embodiment describing a composition, material, component, element, ingredient, feature, integer, operation, and / or method step, this disclosure also specifically includes embodiments consisting of or substantially consisting of such described compositions, materials, components, elements, ingredients, features, integers, operations, and / or method steps. In the case of "consisting of," alternative embodiments exclude any additional compositions, materials, components, elements, ingredients, features, integers, operations, and / or method steps, while in the case of "substantially consisting of," any additional compositions, materials, components, elements, ingredients, features, integers, operations, and / or method steps that substantially affect the basic and novel characteristics are excluded from such embodiments, but any compositions, materials, components, elements, ingredients, features, integers, operations, and / or method steps that do not substantially affect the basic and novel characteristics may be included in the embodiments.

[0085] Any methods, procedures, and operations described herein should not be construed as necessarily requiring them to be performed in the order discussed or illustrated, unless explicitly stated as such. It should also be understood that, unless otherwise stated, additional or alternative steps may be employed.

[0086] When a component, element, or layer is mentioned as being "on," "engaged," "connected," or "attached" to another component or layer, it may be directly engaged, connected, or attached to the other component, element, or layer, or an intermediary element or layer may be present. Conversely, when an element is mentioned as being "directly on," "directly engaged," "directly connected," or "directly attached" to another component or layer, an intermediary element or layer may not be present. Other terms used to describe relationships between elements should be interpreted similarly (e.g., "between" versus "directly between," "adjacent" versus "directly adjacent," etc.). As used herein, the term "and / or" includes a combination of one or more related enumerations.

[0087] Although the terms first, second, third, etc., may be used herein to describe various steps, elements, components, regions, layers, and / or sections, these steps, elements, components, regions, layers, and / or sections should not be limited by these terms unless otherwise stated. These terms may be used only to distinguish one step, element, component, region, layer, or section from another. Unless the context clearly indicates otherwise, terms such as “first,” “second,” and other numerical terms used herein do not imply order or sequence. Therefore, the first step, element, component, region, layer, or section discussed below may be referred to as the second step, element, component, region, layer, or section without departing from the teachings of the exemplary embodiments.

[0088] For ease of description, spatially or temporally relative terms such as "before," "after," "inside," "outside," "below," "below," "lower part," "above," "upper part," etc., may be used herein to describe the relationship between one element or feature as shown in the accompanying drawings and other elements or features(s). In addition to the orientations shown in the accompanying drawings, spatially or temporally relative terms may be intended to cover different orientations of the apparatus or system during use or operation.

[0089] Throughout this disclosure, numerical values ​​represent approximate measurements or range limits and encompass slight deviations from a given value and embodiments that substantially have the mentioned value as well as embodiments that precisely have the mentioned value. Except in the detailed description of the working examples provided at the end, all numerical values ​​of parameters (e.g., quantities or conditions) in this specification (including the appended claims) should be understood to be modified in all cases by the term “about”, regardless of whether “about” actually appears before the numerical value. “About” means that the numerical value allows for a certain degree of slight inaccuracy (approaching the exact value to a certain extent; substantially or reasonably approximating the value; almost). If the inaccuracy provided by “about” is not otherwise understood in the art in this ordinary sense, then “about” as used herein refers to at least a deviation that can be caused by ordinary methods of measuring and using such parameters. For example, “about” may include deviations of less than or equal to 5%, optionally less than or equal to 4%, optionally less than or equal to 3%, optionally less than or equal to 2%, optionally less than or equal to 1%, optionally less than or equal to 0.5%, and in some respects optionally less than or equal to 0.1%.

[0090] In addition, the disclosure of the range includes disclosure of all values ​​throughout the range and disclosure of further subdivisions of the range, including disclosure of the endpoints and subranges given by the range.

[0091] As used herein, the terms “composition” and “material” are used interchangeably to broadly refer to a substance containing at least preferred chemical components, elements, or compounds, but may also contain additional elements, compounds, or substances, including trace impurities, unless otherwise specified. A “X-based” composition or material broadly refers to a composition or material in which “X” is the single largest component of the composition or material based on a weight percentage (%). This may include compositions or materials having more than 50% by weight of X, as well as those having less than 50% by weight of X, provided that X is the single largest component of the composition or material based on its total weight.

[0092] As used herein, the term "metal" can refer to a pure elemental metal or an alloy of an elemental metal with one or more other metallic or nonmetallic elements (referred to as "alloying" elements). Alloying elements can be selected to impart certain desired properties to the alloy that are not exhibited by the base metallic element.

[0093] The example implementation will now be described more fully with reference to the accompanying drawings.

[0094] The systems and methods disclosed herein can be used to evaluate the properties of newly developed reference electrode assemblies and / or individual components in a laboratory setting without requiring the assembly of a complete electrochemical cell with a three-electrode configuration.

[0095] Figure 1 An exploded perspective view of an electrochemical cell 10 is depicted, comprising a positive electrode layer 12, a negative electrode layer 14, and a reference electrode assembly 16. The reference electrode assembly 16 serves as a reference for accurately measuring the individual electrochemical potentials of the positive electrode layer 12 and the negative electrode layer 14 without interfering with the operation of the electrochemical cell 10. In the assembly, the positive electrode layer 12 may be disposed on the main surface of the positive electrode current collector 18, the negative electrode layer 14 may be disposed on the main surface of the negative electrode current collector 20, and an insulating member 22 may be disposed between the positive electrode layer 12 and the negative electrode layer 14, thereby electrically insulating them from each other. In practice, the positive electrode current collector 18 and the negative electrode current collector 20 may be electrically connected to each other outside the electrochemical cell 10 via an external circuit 34. The positive electrode current collector 18 and the negative electrode current collector 20 may be electrically connected to a power source or load 32 and a controller 36 via the external circuit 34. The reference electrode assembly 16 may be electrically connected to the controller 36 via a reference circuit 38.

[0096] The positive electrode layer 12 is porous and may include one or more electrochemically active materials capable of reversibly redox reactions with lithium, such as materials capable of lithium intercalation and deintercalation, alloying and dealloying, or plating and stripping. In one form, the positive electrode layer 12 may include an intercalation host material capable of undergoing reversible insertion or intercalation of lithium ions. In this case, the intercalation host material of the positive electrode layer 12 may include a layered oxide represented by the formula LiMeO2, an olivine-type oxide represented by the formula LiMePO4, a spinel-type oxide represented by the formula LiMe2O4, lithium hydroxyphosphide represented by one or two of the following formulas LiMeSO4F or LiMePO4F, or combinations thereof, wherein Me is a transition metal (e.g., Co, Ni, Mn, Fe, Al, V, or combinations thereof). In another form, the positive electrode layer 12 may include a conversion material comprising components capable of reversibly electrochemically reacting with lithium, wherein the components undergo a phase transition or a change in crystal structure accompanied by a change in oxidation state. In this embodiment, the conversion material of the positive electrode layer 12 may include sulfur, selenium, tellurium, iodine, halides (e.g., fluorides or chlorides), sulfides, selenides, tellurides, iodides, phosphides, nitrides, oxides, oxysulfides, oxyfluorides, sulfur-fluorides, sulfur-oxyfluorides, or lithium and / or metal compounds thereof. Suitable examples of metals included in the conversion material of the positive electrode layer 12 include iron, manganese, nickel, copper, and cobalt. In an embodiment, the electrochemically active material of the positive electrode layer 12 may be mixed with a polymer binder to provide a positive electrode layer 12 with structural integrity. Examples of polymer binders include polyvinylidene fluoride (PVdF), ethylene propylene diene monomer (EPDM), styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyacrylic acid, and mixtures thereof. The positive electrode layer 12 may optionally include particles of a conductive material, which may include, for example, very fine particles of high surface area carbon black.

[0097] The negative electrode layer 14 may be porous or non-porous. In some aspects, the negative electrode layer 14 may include lithium (Li) metal, be substantially composed of lithium (Li) metal, or be composed entirely of lithium (Li) metal. For example, in some aspects, the negative electrode layer 14 may include more than 97% or more than 99% lithium by weight, and may be substantially free of elements or compounds that undergo a reversible redox reaction with lithium during operation of the electrochemical cell 10. In other aspects, the negative electrode layer 14 may include one or more electrochemically active materials that can undergo reversible insertion or intercalation of lithium ions at a lower electrochemical potential than that of the electrochemically active material of the positive electrode layer 12, such that an electrochemical potential difference exists between the positive electrode layer 12 and the negative electrode layer 14. The electrochemically active material of the negative electrode layer 14 can be broadly described as an intercalation host material. Examples of embedded host materials for the electrochemically active material of the negative electrode layer 14 include carbon-based materials (e.g., graphite, activated carbon, carbon black, carbon nanotubes, and graphene), lithium, lithium-based materials, silicon, silicon-based alloys or composites, tin oxide, aluminum, indium, zinc, germanium, silicon oxide, titanium oxide, lithium titanate, and combinations thereof. For the same purpose, the same polymer binder materials (PVdF, EPDM, SBR, CMC, polyacrylic acid) and conductive particles (high surface area carbon black) used in the positive electrode layer 12 may also be mixed with the electrochemically active material of the negative electrode layer 14.

[0098] The positive electrode current collector 18 and the negative electrode current collector 20 may include materials capable of collecting free electrons and reversibly delivering free electrons to and from their respective electrode layers 12, 14. For example, the positive electrode current collector 18 and the negative electrode current collector 20 may include conductive metals, such as transition metals or alloys thereof. In embodiments, the negative electrode current collector 20 may comprise copper, nickel, an iron alloy (e.g., stainless steel), or titanium, and the positive electrode current collector 18 may comprise aluminum, nickel, or an iron alloy (e.g., stainless steel). Other conductive metals may, of course, be used if desired.

[0099] The isolator component 22 is configured to physically separate and electrically insulate the positive electrode layer 12 and the negative electrode layer 14 from each other, while allowing ions to flow freely between them. The isolator component 22 may comprise a nonwoven material, such as a man-made sheet, mesh, or mat of oriented or randomly oriented fibers. The isolator component 22 may comprise a microporous polymer material, such as a microporous polyolefin-based membrane or film. For example, the isolator component 22 may comprise a single polyolefin or a combination of polyolefins, such as polyethylene (PE), polypropylene (PP), polyamide (PA), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), and / or polyvinyl chloride (PVC). In one form, the isolator component 22 may comprise a laminate of one or more polymeric materials, such as a laminate of PE and PP. The thickness of the isolator component 22 may be in the range of 20 μm to 30 μm, and the porosity may be in the range of 35% to 50%.

[0100] The reference electrode assembly 16 is configured to serve as a reference for monitoring the potentials of the positive electrode layer 12 and the negative electrode layer 14 without interfering with the operation of the electrochemical cell 10, and in particular, without inhibiting the free flow of ions between the positive electrode layer 12 and the negative electrode layer 14. The reference electrode assembly 16 includes an isolation layer 24 having a first main surface 26, a reference electrode current collector layer 28 deposited on the first main surface 26 of the isolation layer 24, and an electroactive reference electrode layer 30 deposited on the first main surface 26 of the isolation layer 24, such that at least a portion of the reference electrode layer 30 partially overlaps with the reference electrode current collector layer 28 on the first main surface 26 of the isolation layer 24. The reference electrode assembly 16 may be disposed between the positive electrode layer 12 and the negative electrode layer 14, such that the reference electrode current collector layer 28 and the reference electrode layer 30 are electrically insulated from the positive electrode layer 12 and the negative electrode layer 14 by the isolation member 22 and the isolation layer 24.

[0101] The separator layer 24 is configured to electrically insulate the reference electrode current collector layer 28 and the reference electrode layer 30 from the positive electrode layer 12 or the negative electrode layer 14, while allowing ions to flow freely through it. The separator layer 24 can serve as a substrate on which the reference electrode current collector layer 28 and the reference electrode layer 30 are formed, and can help position the reference electrode current collector layer 28 and the reference electrode layer 30 within the electrochemical cell 10. Similar to the separator component 22, the separator layer 24 may comprise an electrically insulating and ion-permeable microporous material. For example, the separator layer 24 may comprise a microporous polymer material. The separator layer 24 may have a thickness in the range of 10 μm to 20 μm and a porosity greater than 40% and less than 80%.

[0102] The reference electrode current collector layer 28 is configured to provide a conductive path between the reference electrode layer 30 and the reference circuit 38 without inhibiting the free flow of ions between the positive electrode layer 12 and the negative electrode layer 14 of the electrochemical cell 10. The reference electrode current collector layer 28 may include a material capable of collecting free electrons and reversibly transferring them to and from the reference electrode layer 30 without inhibiting ion transport through the reference electrode assembly 16. For example, the reference electrode current collector layer 28 may comprise a conductive carbon-based material or a conductive metal, such as a transition metal or an alloy thereof. Examples of conductive metals include copper, nickel, iron (e.g., stainless steel), titanium, aluminum, and / or nickel. Other conductive metals may be used if desired. The reference electrode current collector layer 28 may be deposited on the first main surface 26 of the insulating layer 24 with a thickness ranging from 10 nanometers to 1 micrometer.

[0103] The reference electrode layer 30 at least partially overlaps with the reference electrode current collector layer 28 on the first main surface 26 of the separator layer 24 and is configured to exhibit a known, generally constant electrochemical potential that can be used as a reference when measuring the respective electrochemical potentials of the positive electrode layer 12 and the negative electrode layer 14. Thus, the reference electrode layer 30 preferably comprises an electrochemically active reference electrode material that exhibits a known, generally constant (or little change) chemical potential during operation of the electrochemical cell 10, for example, during repeated charge and discharge cycles. Furthermore, the reaction kinetics of the electrochemically active reference electrode material of the reference electrode layer 30 can be readily obtained such that the small current required to measure the electrochemical potential difference between the reference electrode layer 30 and the positive and negative electrode layers 12 should not cause polarization of the reference electrode layer 30 itself. For example, the electrochemically active reference electrode material of the reference electrode layer 30 may comprise lithium iron phosphate (LiFePO4, LFP) or lithium titanium oxide (Li4Ti5O4). 12 (LTO). The reference electrode layer 30 can be deposited on the first main surface 26 of the isolation layer 24 with a thickness ranging from 200 nanometers to 10 micrometers.

[0104] The controller 36 is electrically connected via the positive electrode current collector 18 and external circuitry 34 to (i) the positive electrode layer 12, (ii) the negative electrode layer 14 via the negative electrode current collector 20 and external circuitry 34, and (iii) the reference electrode layer 30 via the reference electrode current collector layer 28 and reference circuitry 38. The controller 36 can be configured to measure the potential difference between the positive electrode layer 12 and the negative electrode layer 14 in real time to determine the total electrochemical potential (Ecell) of the electrochemical cell 10 during cycling. The controller 36 can also be configured to measure the potential difference between the reference electrode layer 30 and the positive electrode layer 12, and calculate the electrochemical potential (Epos) of the positive electrode layer 12 based on this measurement. Furthermore, the controller 36 can be configured to measure the potential difference between the reference electrode layer 30 and the negative electrode layer 16, and calculate the electrochemical potential (Eeg) of the negative electrode layer 14 based on this measurement. The total electrochemical potential of the electrochemical cell 10, as well as the individual electrochemical potentials of the positive electrode layer 12 and the negative electrode layer 14, can be used by the controller 36, for example, to accurately determine the state of charge (SOC) of the electrochemical cell 10. Accurate determination of the SOC of the electrochemical cell 10 can be used to determine certain optimal charging parameters, which can be used to achieve a fast charging rate without compromising the overall functionality and / or long-term cycle stability of the electrochemical cell 10. Furthermore, accurate real-time measurement of the electrochemical potential of the negative electrode layer 14 allows the charging process to proceed at the fastest possible charging rate and terminate before lithium plating occurs.

[0105] The positive electrode layer 12 and negative electrode layer 14, the separator assembly 22, and the reference electrode assembly 16 may be permeated with an electrolyte (not shown) and / or in ionic contact with an electrolyte (not shown), which facilitates lithium-ion permeation through and between the positive electrode layer 12 and negative electrode layer 14 during cycling of the electrochemical cell 10. The electrolyte may be formulated to facilitate lithium-ion transport between the positive electrode layer 12 and negative electrode layer 14 during cycling of the electrochemical cell 10. The electrolyte may be a liquid, solid, or gel polymer electrolyte. The electrolyte may be in solution form and may contain one or more lithium salts dissolved in a non-aqueous aprotic organic solvent or a mixture of non-aqueous aprotic organic solvents. Examples of lithium salts include lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClQ4), lithium tetrachloroaluminate (LiAlCl4), lithium iodide (LiI), lithium bromide (LiBr), lithium thiocyanate (LiSCN), lithium tetrafluoroborate (LiBF4), lithium tetraphenylborate (LiB(C6H5)4), lithium bis(oxalate)borate (LiB(C2O4)2)(LiBOB), lithium difluorooxalate borate (LiBF2(C2O4)), lithium hexafluoroarsenate (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(trifluoromethane)sulfonylimide (LiN(CF3SO2)2), lithium bis(fluorosulfonyl)imide (LiN(FSO2)2)(LiSFI), and combinations thereof. Examples of non-aqueous aprotic organic solvents include organic carbonates, such as cyclic carbonates (e.g., ethylene carbonate (EC), propylene carbonate (PC), butyl carbonate (BC), fluoroethylene carbonate (FEC)), linear carbonates (e.g., dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC)), aliphatic carboxylic acid esters (e.g., methyl formate, methyl acetate, methyl propionate), γ-lactones (e.g., γ-butyrolactone, γ-valerolactone), chain ethers (e.g., 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane), cyclic ethers (e.g., tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane), sulfur-containing compounds (e.g., sulfolane), and combinations thereof.

[0106] Scientific advancements and discoveries can provide reference electrode assemblies for electrochemical cells, for example... Figure 1 The reference electrode assembly 16 described herein brings new material compositions and / or manufacturing methods. Before manufacturing a complete electrochemical cell with the newly developed reference electrode assembly, it may be necessary to test the reference electrode assembly and / or its newly developed individual components in a laboratory or other small-scale setting. The systems and methods disclosed in this invention can be used to evaluate and obtain data related to the performance and / or compatibility of the newly developed reference electrode assembly and / or its individual components without necessarily manufacturing a complete electrochemical cell with a three-electrode configuration, for example... Figure 1The complete three-electrode electrochemical cell 10 is shown. The systems and methods of this disclosure use specially designed battery assemblies with a two-electrode configuration to evaluate newly developed reference electrode assemblies and / or their individual components. Compared to assembling a complete electrochemical cell with a three-electrode configuration for initial testing purposes, using the battery assemblies of this disclosure with a two-electrode configuration requires less material and is less expensive.

[0107] Figure 2 and 3 A system 150 for evaluating the properties of a current collector layer deposited on an insulating layer is described, and it is proposed for use in electrochemical cells for cycling lithium ions (e.g., Figure 1 The reference electrode assembly of the electrochemical cell 10 described herein. System 150 includes a test cell assembly 152 and a controller 154. The test cell assembly 152 includes a metal casing 158 defining an interior 160 and a dual-electrode electrochemical test cell 162 disposed within the interior 160 and electrically connected to the metal casing 158. The test cell assembly 152 may also include metal spacers 164 and / or bias members 166, which help position the test cell 162 within the interior 160 and maintain pressure on the test cell 162, and ensure good contact between the components of the test cell 162 and between the test cell 162 and the metal casing 158. Figure 2 and 3 The metal casing 158 and test battery 162 of the test battery assembly 152 shown are generally circular, and this configuration is commonly referred to as a button cell configuration. However, the battery assemblies disclosed herein are not limited to this configuration and may take on different shapes.

[0108] The metal casing 158 includes a top 168 and a bottom 170, which together define an interior 160 of the metal casing 158. The top 168 and the bottom 170 can be hermetically sealed together by a gasket 172. The metal casing 158 may be made of a conductive and chemically inert metal, such as stainless steel. The gasket 172 may be made of a flexible electrically insulating material, such as rubber.

[0109] The test battery 162 includes a working electrode in the form of an electroactive layer 174, a counter electrode in the form of a lithium metal layer, and a separator assembly 178 disposed between the electroactive layer 174 and the lithium metal layer 176. In the assembly ( Figure 3 In this circuit, the electroactive layer 174 and the lithium metal layer 176 are electrically connected to the metal casing 158, and the metal casing 158 is electrically connected to the controller 154 via an external circuit 156. Figure 3In this assembly, the electroactive layer 174 is electrically connected to the bottom 170 of the metal casing 158, the lithium metal layer 176 is electrically connected to the top 168 of the metal casing 158, and the top 168 and bottom 170 of the metal casing 158 are electrically insulated from each other by a gasket 172. The separator assembly 178 includes a separator layer 180 and a current collector layer 182 directly deposited on the separator layer 180 and mechanically connected thereto.

[0110] The test cell 162 was configured to simulate the bonding of current collector layer 182 to, for example, Figure 1 In the case of a complete three-electrode electrochemical cell 10, the current collector layer 182 will experience the following physical and electrochemical conditions as part of the reference electrode assembly. Therefore, the compositions of the separator layer 180 and the electroactive layer 174 can be substantially the same as those of the separator layer 24 and the reference electrode layer 30, respectively. The current collector layer 182 will coexist with the separator layer 24 and the reference electrode layer 30 or be shared by the separator layer 24 and the reference electrode layer 30.

[0111] Cyclic voltammetry experiments can be performed by system 150 on test cell 162 of test cell assembly 152 and on control cell of control cell assembly (not shown) to evaluate the characteristics of current collector layer 182 and / or assess the compatibility and / or electrochemical stability of current collector layer 182 in the environment of test cell 162. The control cell and control cell assembly can be configured as experimental controls to allow for accurate evaluation of current collector layer 182. Thus, the control cell may include the same components arranged in substantially the same manner as the components of test cell 162, except that the control cell may not include the current collector layer 182 being evaluated. In some cases, cyclic voltammetry experiments can be performed on the control cell by system 150 prior to cyclic voltammetry experiments on test cell 162. In this case, the cyclic voltammetry data generated during the cyclic voltammetry experiment on the control cell can be stored in the memory of controller 154 for future reference when evaluating certain characteristics of current collector layer 182.

[0112] Cyclic voltammetry experiments performed on test battery 162 and control battery can be controlled by controller 154. During the cyclic voltammetry experiment, a potential can be applied between the electroactive layer 174 and the lithium metal layer 176 by controller 154. The potential of the electroactive layer 174 can be calculated by controller 154 based on the potential applied between the electroactive layer 174 and the lithium metal layer 176 and the potential of the lithium metal layer 176, which maintains a constant potential. During the cyclic voltammetry experiment, the potential of the electroactive layer 174 (relative to the potential of the lithium metal layer 176) changes from an initial potential to a set potential, and then the potential of the electroactive layer 174 changes in the opposite direction to return to the initial potential. As the potential of the electroactive layer 174 cycles, the current at the electroactive layer 174 can be continuously, periodically, or repeatedly measured by controller 154 and stored in memory. During cyclic voltammetry experiments, the current and potential of the electroactive layer 174 are recorded by controller 154 and can be stored in the memory of controller 154. The current and potential of the electroactive layer 174 recorded during cyclic voltammetry experiments (cyclic voltammetry data) can be plotted relative to each other (current, Ivs. potential, V) to obtain a cyclic voltammetry diagram. For example, the cyclic voltammetry diagram can be prepared by controller 154 using cyclic voltammetry data generated during cyclic voltammetry experiments performed on a control cell and cyclic voltammetry data generated during cyclic voltammetry experiments performed on a test cell 162.

[0113] Comparison of the cyclic voltammograms of the test cell 162 and the control cell can provide an indicator of the ion permeability of the current collector layer 182 in the environment of the test cell 162, as well as an indicator of the compatibility and / or electrochemical stability of the current collector layer 182. Figure 4 Example cyclic voltammetry diagram 220 (solid line) describes the current (I) 200 vs. potential (V) 210 of test battery 162. Figure 5 Example cyclic voltammetry diagram 230 (dashed line) describes the current (I) 200 vs. potential (V) 210 of a control battery. Figure 4 and 5As shown, the cyclic voltammogram 220 of the test battery 162 and the cyclic voltammogram 230 of the control battery are substantially the same. There are no identifiable differences between the cyclic voltammogram 220 of the test battery 162 and the cyclic voltammogram 230 of the control battery, indicating that the current collector layer 182 does not inhibit the flow of lithium ions between the electroactive layer 174 and the lithium metal layer 176, and therefore, the current collector layer 182 exhibits sufficient ion permeability to be used as a reference electrode current collector layer in a reference electrode assembly. Furthermore, there are no identifiable differences between the cyclic voltammogram 220 of the test battery 162 and the cyclic voltammogram 230 of the control battery, indicating that the presence of the current collector layer 182 in the test battery 162 does not weaken or alter the cycle performance of the test battery 162 (compared to the cycle performance of the control battery), and therefore, the current collector layer 182 is compatible with the environment of the test battery 162 and is electrochemically stable in the environment of the test battery 162.

[0114] On the other hand, if the cyclic voltammogram 220 of the test cell 162 is significantly different from the cyclic voltammogram 230 of the control cell, such difference may indicate that the current collector layer 182 has low ion permeability in the environment of the test cell 162, and / or that the current collector layer 182 is incompatible and / or electrochemically unstable.

[0115] The thickness of the current collector layer 182 can be determined using atomic force microscopy (AFM).

[0116] The resistivity of current collector layer 182 can be determined using a four-point probe technique.

[0117] Figure 6 and 7 A system 250 for evaluating the properties of a current collector layer and a reference electrode layer deposited on an insulating layer is described, and it is proposed for use in electrochemical cells for cycling lithium ions (e.g., Figure 1 The reference electrode assembly of the electrochemical cell 10 described herein. System 250 is similar in many respects to the one described above. Figure 2-5 System 150 is discussed, and common topics need not be repeated here. System 250 includes a test battery assembly 252 and a controller 254. The test battery assembly 252 includes a metal casing 258 defining an interior 260 and a dual-electrode electrochemical test cell 262 disposed within the interior 260 and electrically connected to the metal casing 258. The test battery assembly 252 may further include metal spacers 264 and / or bias members 266, which help position the test cell 262 within the interior 260 and maintain pressure on the test cell 262 and ensure good contact between the components of the test cell 262 and between the test cell 262 and the metal casing 258.

[0118] The metal casing 258 includes a top 268 and a bottom 270, which together define an interior 260 of the metal casing 258. The top 268 and the bottom 270 can be hermetically sealed together by a gasket 272. The metal casing 258 may be made of a conductive and chemically inert metal, such as stainless steel. The gasket 272 may be made of a flexible electrically insulating material, such as rubber.

[0119] The test battery 262 includes a lithium metal layer 276, an electrical insulating layer 284, and a separator assembly 278 disposed between the lithium metal layer 276 and the electrical insulating layer 284. The separator assembly 278 includes a separator layer 280 having a first main surface and an opposing second main surface, a current collector layer 282 deposited on the first main surface of the separator layer 280, and an electroactive layer 274 deposited on the first main surface of the separator layer 280, such that the electroactive layer 274 at least partially overlaps with the current collector layer 282 on the first main surface of the separator layer 280. Figure 6 and 7 As shown, in some cases, the current collector layer 282 can be directly deposited on and mechanically connected to the first main surface of the isolation layer 280, and the electroactive layer 274 can be directly deposited on and mechanically connected to the current collector layer 282. During assembly ( Figure 7 In the process, the current collector layer 282 is in direct physical contact with the electroactive layer 274 and is electrically insulated from the lithium metal layer 276 through the isolation layer 280.

[0120] The diameter (or width and length) of the insulating component assembly 278 is larger than the diameter of the electrical insulation layer 284. Thus, during assembly (… Figure 7 In this configuration, the isolator assembly 278 extends beyond the periphery 286 of the electrical insulation layer 284, such that the central region of the isolator assembly 278 is physically separated from the bottom 270 of the metal shell 258 by the electrical insulation layer 284, and the peripheral region of the isolator assembly 278 is in direct physical contact with the bottom 270 of the metal shell 258. Figure 7 In this arrangement, the central region of the electroactive layer 274 is physically separated from the bottom 270 of the metal casing 258 by the electrical insulating layer 284, and the peripheral region of the electroactive layer 274 is in direct physical contact with the bottom 270 of the metal casing 258. In this arrangement, when a cyclic voltammetry experiment is performed on the test battery 262, lithium ions can be guided to flow through the separator assembly 278 in the direction of arrow 288. Specifically, lithium ions can be guided to flow through the central region of the electroactive layer 274 in a planar direction parallel to the facing surface of the electrical insulating layer 284, and lithium ions can be guided to flow through the peripheral region of the electroactive layer 274 in a transverse direction perpendicular to the facing surface of the electrical insulating layer 284. Thus, the flow of lithium ions through the separator assembly 278 can simulate the flow of lithium ions through a complete three-electrode electrochemical cell, such as... Figure 1 The flow of the reference electrode assembly of the electrochemical cell 10.

[0121] In assembly ( Figure 7 In this configuration, the electroactive layer 274 and the lithium metal layer 276 are electrically connected to the metal casing 258, and the metal casing 258 is electrically connected to the controller 254 via an external circuit 256. Figure 7 In the case, the electroactive layer 274 is electrically connected to the bottom 270 of the metal shell 258, the lithium metal layer 276 is electrically connected to the top 268 of the metal shell 258, and the top 268 and bottom 270 of the metal shell 258 are electrically insulated from each other by a gasket 272.

[0122] The test battery 262 is configured to simulate the separator assembly 278 (including separator layer 280, current collector layer 282, and electroactive layer 274) in which the separator assembly 278 is used as such Figure 1 The physical and electrochemical conditions that the reference electrode assembly in the complete three-electrode electrochemical cell 10 will experience are as follows. Therefore, the composition of the separator 280, the current collector layer 282, and the electroactive layer 274 may be substantially the same as the composition of the separator 24, the reference electrode current collector layer 28, and the reference electrode layer 30, which will be used or proposed to be used.

[0123] The cyclic voltammetry experiment can be performed by controller 254 on test battery assembly 252 and control battery 362 of control battery assembly 352. Figure 8 The process is conducted to evaluate the characteristics of the separator assembly 278 and / or assess its compatibility and / or electrochemical stability in the environment of the test battery 262. Control batteries 362 and 352 can be configured as experimental controls to allow for accurate evaluation of the separator assembly 278. Thus, control battery 362 may include the same components arranged in substantially the same manner as those of the test battery 262, except that control battery 362 may not include the separator assembly 278 or the electrically insulating layer 284. Control batteries 362 and 352 are similar in many respects to those described above. Figure 6-7 The test battery assembly 252 discussed here is similar to the test battery 262, and the common topics need not be repeated here.

[0124] like Figure 8As shown, the control battery assembly 352 may include a metal casing 358 defining an interior 360 and a dual-electrode electrochemical control battery 362 disposed within the interior 360 and electrically connected to the metal casing 358. Similar to the test battery assembly 252, the control battery assembly 352 may also include a metal spacer 364 and / or a bias member 366. The metal casing 358 may include a top 368 and a bottom 370, which together define the interior 360 of the metal casing 358. The top 368 and the bottom 370 may be hermetically sealed together by a gasket (not shown). The control battery 362 includes a lithium metal layer 376, an electroactive layer 374 deposited on the main surface of a current collector foil 382, ​​and an isolation layer 380 disposed between the lithium metal layer 376 and the electroactive layer 374. During assembly, the electroactive layer 374 and the lithium metal layer 376 are electrically connected to the metal casing 358, and the metal casing 358 is electrically connected to a controller 254 via external circuitry 356. Figure 8 In the case, the electroactive layer 374 is electrically connected to the bottom 370 of the metal shell 358 via the current collector foil 382, ​​the lithium metal layer 376 is electrically connected to the top 368 of the metal shell 358, and the top 368 and bottom 370 of the metal shell 358 are electrically insulated from each other by a gasket (not shown).

[0125] Cyclic voltammetry experiments performed on test battery 262 and control battery 362 can be controlled by controller 254. During the cyclic voltammetry experiment on test battery 262, a potential can be applied between electroactive layer 274 and lithium metal layer 276 by controller 254. The potential of electroactive layer 274 can be calculated by controller 254 based on the potential applied between electroactive layer 274 and lithium metal layer 276 and the potential of lithium metal layer 276 which remains constant. During the cyclic voltammetry experiment on test battery 262, the potential of electroactive layer 274 (relative to the potential of lithium metal layer 276) changes from an initial potential to a set potential, and then the potential of electroactive layer 274 changes in the opposite direction to return to the initial potential. As the potential of electroactive layer 274 cycles, the current at electroactive layer 274 can be continuously, periodically, or repeatedly measured by controller 254 and stored in memory. The current and potential of the electroactive layer 274 can be recorded by the controller 254 during cyclic voltammetry experiments and can be stored in the memory of the controller 254. The current and potential of the electroactive layer 274 recorded during cyclic voltammetry experiments (cyclic voltammetry data) can be plotted relative to each other (current, I vs. potential, V) to obtain a cyclic voltammetry diagram of the test battery 262. The same cyclic voltammetry experiment performed on the test battery 262 can be performed on the control battery 362, wherein a potential is applied between the electroactive layer 374 and the lithium metal layer 376 by the controller 254. For example, a cyclic voltammetry diagram can be prepared by the controller 254 using the cyclic voltammetry data generated during the cyclic voltammetry experiment performed on the control battery 362, and using the cyclic voltammetry data generated during the cyclic voltammetry experiment performed on the test battery 262. In some cases, a cyclic voltammetry experiment can be performed on the control battery 362 by the control battery 254 before the cyclic voltammetry experiment is performed on the test battery 262. In this case, the cyclic voltammetry data generated during the cyclic voltammetry experiment on the control battery 362 can be stored in the memory of the controller 254 for future reference when evaluating certain characteristics of the separator assembly 278.

[0126] Comparison of the cyclic voltammograms of test cell 262 and control cell 362 can provide an indicator of the electrochemical performance and / or electrochemical stability of the separator assembly 278 in the environment of test cell 262. Figure 9 Example cyclic voltammogram 320 (solid line) depicts the current (I) 300 vs. potential (V) 310 of test battery 262, and example cyclic voltammogram 330 (dashed line) depicts the current (I) 300 vs. potential (V) 310 of control battery 362. Figure 9As shown, the voltage peaks in the cyclic voltammetry plot 320 of test battery 262 and the voltage peaks in the cyclic voltammetry plot 330 of control battery 362 are substantially aligned with each other. This alignment of voltage peaks in the cyclic voltammetry plots 320 and 330 of control battery 362 indicates that the separator assembly 278 (including separator layer 280, current collector layer 282, and electroactive layer 274) can be used as, for example... Figure 1 The reference electrode assembly in the complete three-electrode electrochemical cell 10 is used to obtain accurate electrochemical potential measurements of the positive and / or negative electrodes of the electrochemical cell.

[0127] The above description of embodiments has been provided for illustrative and descriptive purposes. It is not intended to be exhaustive or limiting of this disclosure. Elements or features of a particular embodiment are generally not limited to that embodiment, but are interchangeable where applicable and can be used in selected embodiments, even if not specifically shown or described. The same applies to variations in many ways. Such variations should not be considered a departure from this disclosure, and all such modifications are intended to be included within the scope of this disclosure.

Claims

1. A system for evaluating the characteristics of a current collector layer in a reference electrode assembly of a cyclic lithium-ion electrochemical cell, the system comprising: Controller; as well as A test battery assembly includes: A first metal housing, including a top and a bottom, together defining the interior of the first metal housing, wherein the top of the first metal housing is electrically connected to the controller via a first electrical connector, and the bottom of the first metal housing is electrically connected to the controller via a second electrical connector. A test battery disposed inside the first metal casing includes a first electroactive layer, a first lithium metal layer, and a separator assembly disposed between the first electroactive layer and the first lithium metal layer. The separator assembly includes a first separator layer having a first main surface and a current collector layer deposited on the first main surface of the first separator layer. The current collector layer is electrically insulated from the lithium metal layer through the first separator layer, and the current collector layer is in direct physical contact with the first electroactive layer. The first lithium metal layer is electrically connected to the top of the first metal shell, and the first electroactive layer is electrically connected to the bottom of the first metal shell.

2. The system of claim 1, wherein the test battery assembly further comprises a metal spacer and a biasing member disposed between the test battery and the top of the first metal casing.

3. The system of claim 1, wherein the top and bottom of the first metal casing are electrically insulated from each other by a gasket.

4. The system of claim 1, wherein the controller is configured to generate a test battery cyclic voltammogram by applying a potential between the first electroactive layer and the first lithium metal layer, cycling the applied potential between an initial potential and a set potential, and measuring the current at the first electroactive layer while the applied potential cycles between the initial potential and the set potential.

5. The system of claim 4, wherein the controller is configured to provide an indicator of at least one of the following: ion permeability of the current collector layer in the environment of the test battery, compatibility of the current collector layer with the first electroactive layer, or electrochemical stability of the current collector layer.

6. The system according to claim 1, further comprising: A comparative battery assembly includes: A second metal housing, comprising a top and a bottom that together define the interior of the second metal housing, wherein the top of the second metal housing is electrically connected to the controller via a third electrical connector, and the bottom of the second metal housing is electrically connected to the controller via a fourth electrical connector; and A control battery disposed inside the second metal casing, the control battery comprising a second electroactive layer, a second lithium metal layer, and a second insulating layer disposed between the second electroactive layer and the second lithium metal layer and in direct physical contact with the second electroactive layer and the second lithium metal layer. The second lithium metal layer is electrically connected to the top of the second metal shell, and the second electroactive layer is electrically connected to the bottom of the second metal shell.

7. The system of claim 6, wherein the controller is configured to generate a reference battery cyclic voltammogram by applying a potential between the second electroactive layer and the second lithium metal layer, cycling the applied potential between an initial potential and a set potential, and measuring the current at the second electroactive layer while the applied potential cycles between the initial potential and the set potential.

8. A method for evaluating the properties of the current collector layer according to claim 1, the method comprising: An electric potential is applied between the first electroactive layer and the first lithium metal layer; The potential is cyclical between the initial potential and the set potential; As the potential cycles between the initial potential and the set potential, the current at the first electroactive layer is measured. Calculate the potential of the first electroactive layer; Generate a test cell cyclic voltammogram of the current at the first electroactive layer relative to the potential of the first electroactive layer; as well as The cyclic voltammogram of the test battery is compared with that of the control battery to obtain an indicator of at least one of the following: the ion permeability of the current collector layer in the environment of the test battery, the compatibility of the current collector layer with the first electroactive layer, or the electrochemical stability of the current collector layer.

9. A system for evaluating the characteristics of a reference electrode assembly for a cyclic lithium-ion electrochemical cell, the system comprising: Controller; as well as Test battery assemblies, including: A first metal housing, comprising a top and a bottom that together define the interior of the first metal housing, wherein the top of the first metal housing is electrically connected to the controller via a first electrical connector, and the bottom of the first metal housing is electrically connected to the controller via a second electrical connector; as well as A test battery disposed inside the first metal casing, the test battery comprising a first lithium metal layer, an electrically insulating layer, and a separator assembly disposed between the first lithium metal layer and the electrically insulating layer, the separator assembly comprising a first separator layer having a first main surface, a current collector layer deposited on the first main surface of the first separator layer, and a first electroactive layer deposited on the first main surface of the first separator layer, such that the first electroactive layer at least partially overlaps with the current collector layer. The current collector layer is in direct physical contact with the first electroactive layer and is electrically insulated from the lithium metal layer through the first insulating layer. The isolation assembly extends beyond the outer periphery of the electrical insulation layer, such that the central region of the first electroactive layer is physically separated from the bottom of the first metal shell through the electrical insulation layer, and the outer periphery of the first electroactive layer is in direct physical contact with the bottom of the first metal shell.

10. The system of claim 9, wherein the first lithium metal layer is electrically connected to the top of the first metal shell, and the first electroactive layer is electrically connected to the bottom of the first metal shell.

11. The system of claim 9, wherein the electrical insulating layer is disposed on the bottom of the first metal casing, and the separator assembly is disposed on the bottom of the first metal casing, above the electrical insulating layer, such that during cycling of the test battery, electrons flow in a planar direction through the central region of the first electroactive layer and in a lateral direction through the peripheral region of the first electroactive layer.

12. The system of claim 9, wherein the controller is configured to generate a test battery cyclic voltammetry diagram by applying a potential between the first electroactive layer and the first lithium metal layer, cycling the applied potential between an initial potential and a set potential, and measuring the current at the first electroactive layer while the applied potential cycles between the initial potential and the set potential.

13. The system of claim 12, wherein the controller is configured to provide an indicator of at least one of the electrochemical performance of the separator assembly or the electrochemical stability of the separator assembly in the environment of the test battery.

14. The system according to claim 9, further comprising: Compared to battery assemblies, including: A second metal housing, comprising a top and a bottom that together define the interior of the second metal housing, wherein the top of the second metal housing is electrically connected to the controller via a third electrical connector, and the bottom of the second metal housing is electrically connected to the controller via a fourth electrical connector; and A control battery disposed inside the second metal casing, the control battery comprising a second lithium metal layer, a second electroactive layer disposed on a current collector foil, and a second insulating layer disposed between the second lithium metal layer and the second electroactive layer. The second lithium metal layer is electrically connected to the top of the second metal shell, and the second electroactive layer is electrically connected to the bottom of the second metal shell via the current collector foil.

15. The system of claim 14, wherein the current collector foil is in physical and electrical contact with the bottom of the second metal shell.

16. A method for evaluating the properties of the spacer assembly of claim 9, the method comprising: An electric potential is applied between the first electroactive layer and the first lithium metal layer; The potential is cyclical between the initial potential and the set potential; As the potential cycles between the initial potential and the set potential, the current at the first electroactive layer is measured. Calculate the potential of the first electroactive layer; Generate a test cell cyclic voltammogram of the current at the first electroactive layer relative to the potential of the first electroactive layer; as well as The cyclic voltammogram of the test battery is compared with that of a control battery to obtain an indicator of at least one of the electrochemical performance or electrochemical stability of the separator assembly in the environment of the test battery.

17. The method of claim 16, further comprising: The test battery cyclic voltammogram is compared with the control battery cyclic voltammogram to determine whether the voltage peak described in the test battery cyclic voltammogram aligns with the corresponding voltage peak described in the control battery cyclic voltammogram.

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