Reference electrodes, electrochemical devices comprising reference electrodes, and methods for manufacturing reference electrodes

Abstract

A reference electrode assembly comprises a separator substrate and a reference electrode layer. The separator substrate is porous and electrically insulating. The reference electrode layer is in direct contact with the separator substrate. The reference electrode layer comprises an electroactive material, an electrically conductive material, and a binder. The electrically conductive material is mixed with the electroactive material.

Description

INTRODUCTION

[0001] This section contains background information on the present disclosure that is not necessarily prior art.

[0002] The present disclosure relates to reference electrodes, electrochemical devices comprising reference electrodes, and methods for manufacturing reference electrodes.

[0003] Background: High-energy-density electrochemical cells, such as lithium-ion batteries, can be used in a wide variety of consumer goods and vehicles, including hybrid electric vehicles (HEVs) and electric vehicles (EVs). Typical lithium-ion, lithium-sulfur, and symmetrical lithium-lithium batteries comprise a first electrode, a second electrode, an electrolyte material, and a separator. One electrode serves as the positive electrode or cathode, and the other as the negative electrode or anode. A stack of battery cells can be electrically connected to increase the overall power output.

[0004] Rechargeable lithium-ion batteries function by reversibly transferring lithium ions back and forth between the negative and positive electrodes. A separator and an electrolyte are positioned between the negative and positive electrodes. The electrolyte is suitable for conducting lithium ions and can be in solid (e.g., solid-state diffusion) or liquid form. In certain solid-state batteries, the solid electrolyte can be a layer positioned between the positive and negative electrodes, serving as both an electrical separator and an electrolyte. During charging, the lithium ions move from a cathode (positive electrode) to an anode (negative electrode), and during discharging, they move in the opposite direction. It may be desirable to perform electrochemical analyses on batteries or specific battery components, such as the cathode and anode. SUMMARY

[0005] This section provides a general summary of the revelation and is not a comprehensive revelation of its full scope or all of its features.

[0006] At least one exemplary embodiment relates to a reference electrode arrangement.

[0007] In at least one exemplary embodiment, the reference electrode arrangement comprises a separator substrate and a reference electrode layer. The separator substrate is porous and electrically insulating. The reference electrode layer is in direct contact with the separator substrate. The reference electrode layer comprises an electroactive material, an electrically conductive material, and a binder. The electrically conductive material is mixed with the electroactive material.

[0008] In at least one exemplary embodiment, the reference electrode layer is in the form of a single layer.

[0009] In at least one exemplary embodiment, the reference electrode layer is in the form of a monolayer.

[0010] In at least one exemplary embodiment, the reference electrode arrangement is free of a separate electrically conductive layer.

[0011] In at least one exemplary embodiment, the electrically conductive material is in the form of a plurality of electrically conductive fibers.

[0012] In at least one exemplary embodiment, the electrically conductive fibers define an average length of approximately 0.5 micrometers to approximately 100 micrometers. The electrically conductive fibers define an average diameter of approximately 1 nm to approximately 1 micrometer.

[0013] In at least one exemplary embodiment, the reference electrode arrangement has a total porosity of greater than or equal to approximately 40% to less than or equal to approximately 70%.

[0014] In at least one exemplary embodiment, the reference electrode layer has a thickness of approximately 0.1 micrometers to approximately 5 micrometers.

[0015] The reference electrode layer defines an air permeability of greater than or equal to approximately 40 Gurley-sec to less than or equal to approximately 100 Gurley-sec.

[0016] In at least one exemplary embodiment, the weight ratio of electrically conductive material to electroactive material in the reference electrode layer is greater than or equal to approximately 1:1.

[0017] In at least one exemplary embodiment, the electrically conductive material is selected from the group consisting of: carbon fibers, carbon nanotubes, graphene, gold, aluminum, platinum, copper, composite materials and combinations thereof.

[0018] In at least one exemplary embodiment, the electroactive material is selected from the group consisting of: lithium iron phosphate (LiFePO4), lithium titanate (Li4Ti5O4). 12 ), and a combination thereof. The binder is selected from the group consisting of: carboxymethylcellulose, styrene-butadiene rubber, polyacrylic acid and combinations thereof.

[0019] In at least one exemplary embodiment, the separator substrate defines a thickness of greater than or equal to approximately 10 micrometers to less than or equal to approximately 25 micrometers.

[0020] In at least one exemplary embodiment, the separator substrate comprises a material selected from the group consisting of polyethylene, polypropylene, a ceramic material, and combinations thereof.

[0021] In at least one exemplary embodiment, the separator substrate comprises a solid electrolyte.

[0022] In at least one exemplary embodiment, the reference electrode layer covers an area greater than or equal to approximately 95% of a surface area of ​​the separator substrate.

[0023] At least one exemplary embodiment relates to an electrochemical cell.

[0024] In at least one exemplary embodiment, the electrochemical cell comprises a first electrode, a first current collector, a second electrode, a second current collector, a separator, a reference electrode arrangement, and an electrolyte. The first electrode comprises a first electroactive material and a first binder. The first current collector comprises a first electrically conductive material. The second electrode comprises a second electroactive material and a second binder. The second current collector comprises a second electrically conductive material. The separator is located between the first and second electrodes. The separator is porous and electrically insulating. The reference electrode arrangement comprises a separator substrate and a reference electrode layer. The separator substrate is porous and electrically insulating.The reference electrode layer is in direct contact with the separator substrate. The reference electrode layer comprises a third electroactive material, a third electrically conductive material, and a third binder. The third electrically conductive material is mixed with the third electroactive material. The electrolyte is located in the pores of the first electrode, the second electrode, the separator, the separator substrate, and the reference electrode layer.

[0025] In at least one exemplary embodiment, the reference electrode layer defines an in-plane resistance of less than or equal to approximately 300 Ω.

[0026] At least one exemplary embodiment relates to a method for manufacturing a reference electrode arrangement for an electrochemical cell.

[0027] In at least one exemplary embodiment, the method comprises coating at least one section of a separator substrate with a reference electrode slurry comprising a solvent, a binder, an electroactive material, and an electrically conductive material. The separator substrate is porous and electrically insulating. The method further comprises drying the reference electrode slurry to produce a reference electrode layer in direct contact with the separator substrate. The electroactive material is mixed with the electrically conductive material in the reference electrode layer.

[0028] In at least one exemplary embodiment, the coating process comprises a method selected from the group consisting of: Kiss gravure coating, spray coating, centrifugal coating, airflow laminate coating, and combinations thereof.

[0029] Further applications will become apparent from the description provided herein. The description and specific examples in this summary serve only for illustration and are not intended to limit the scope of the present disclosure. DRAWINGS

[0030] The drawings described herein serve only to illustrate selected embodiments and not all possible embodiments, and are not intended to limit the scope of the present disclosure. Fig. Figure 1 is a schematic view of an electrochemical device. Fig. Figures 2A-2B illustrate electrochemical cells according to at least one exemplary embodiment. Fig. 2A is a perspective view of the electrochemical cell. Fig. 2B is a cross-sectional view of the electrochemical cell. Fig. Figure 3 is a cross-sectional view of a reference electrode arrangement of the electrochemical cell of Fig. 2A-2B. Fig. Figure 4 is an enlarged schematic view of a reference electrode layer of the reference electrode arrangement of Fig. 3. Fig. Figure 5 is a flowchart illustrating a method for manufacturing a reference electrode arrangement according to at least one exemplary embodiment. Fig. Figure 6 is a schematic representation illustrating a process for coating a separator substrate with a reference electrode layer using a Kiss gravure printing process.

[0031] The corresponding reference symbols indicate the corresponding parts in the various views of the drawings. DETAILED DESCRIPTION

[0032] Since exemplary embodiments are provided, this is a careful disclosure that conveys the full scope to those skilled in the art. Numerous specific details are listed, such as examples of specific compositions, components, devices, and processes, to provide a comprehensive understanding of the embodiments of the present disclosure. Those skilled in the art will recognize that specific details need not be used, that exemplary embodiments can be embodied in many different forms, and that none of these should be interpreted in such a way as to limit the scope of the disclosure. In some exemplary embodiments, known processes, known device structures, and known technologies are not described in detail.

[0033] The terminology used herein serves only to describe certain exemplary embodiments and is not to be understood as limiting. As used herein, the singular forms "a," "an," and "the" may also include the plural forms unless the context clearly indicates otherwise. The terms "comprise," "comprehensive," "contain," and "exhibit" are inclusive and therefore specify the presence of indicated features, elements, compositions, steps, integers, processes, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, processes, elements, components, and / or groups thereof.Although the open term "comprehensive" is to be understood as a non-restrictive term used to describe and claim various embodiments set forth herein, in certain aspects the term can alternatively be understood as a more restrictive term, such as "consisting of" or "essentially consisting of". Therefore, for each given embodiment that specifies compositions, materials, components, elements, features, integers, processes and / or process steps, the present disclosure expressly includes embodiments that consist of or essentially consist of such specified compositions, materials, components, elements, features, integers, processes and / or process steps.In the case of "consisting of", the alternative embodiment excludes all additional compositions, materials, components, elements, features, integers, operations and / or process steps, whereas in the case of "essentially consisting of", all additional compositions, materials, components, elements, features, integers, operations and / or process steps that significantly affect the basic and novel properties are excluded from such an embodiment, but all compositions, materials, components, elements, features, integers, operations and / or process steps that do not significantly affect the basic and novel properties may be included in the embodiment.

[0034] All procedural steps, processes, and procedures described herein are not to be interpreted as necessarily having to be carried out in the specific order discussed or illustrated, unless they are expressly designated as the order of execution. It is also understood that additional or alternative steps may be applied unless otherwise indicated.

[0035] When a component, element, or layer is described as being "on" or "interacting" with another element or layer, or as being "connected" or "coupled" with the same, it may be directly on or interacting with, connected to, or coupled with the other component, element, or layer, or there may be intervening elements or layers. Conversely, when an element is described as being "directly on" or "directly interacting with" another element or layer, or as being "directly connected" or "directly coupled" with the same, there must be no intervening elements or layers. Other words used to describe the relationship between elements should be interpreted similarly (e.g.,“Between” as opposed to “directly between”, “neighboring” or “adjacent” as opposed to “directly adjacent” or “directly bordering”, etc.). As used herein, the term “and / or” includes all combinations of one or more of the related listed items.

[0036] Although the terms "first," "second," "third," etc., may be used herein to describe different steps, elements, components, areas, layers, and / or sections, these steps, elements, components, areas, layers, and / or sections should not be limited by these terms unless otherwise specified. These terms should only be used to distinguish one step, element, component, area, layer, or section from another. Terms such as "first," "second," and other numerical terms, when used herein, do not imply any sequence or order unless the context clearly indicates otherwise.Thus, one could refer to a first step, a first element, a first component, a first area, a first layer or a first section, which are discussed below, as a second step, second element, second component, second area, second layer or second section, without deviating from the teachings of the exemplary embodiments.

[0037] Spatially or temporally relative terms such as "before," "after," "inner," "outer," "below," "under," "lower," "above," "upper," and the like may be used herein for the sake of simplicity to describe the relationship of one element or feature to one or more other elements or features, as illustrated in the figures. Spatially or temporally relative terms may be intended to encompass, in addition to the orientation shown in the figures, different orientations of the device or system in use or operation.

[0038] Throughout this entire disclosure, numerical values ​​represent approximate measures or limits for ranges to encompass minor deviations from the stated values ​​and embodiments that approximate the stated value, as well as those that exactly match the stated value. Unlike the working examples at the end of the detailed description, all numerical values ​​of parameters (e.g., quantities or conditions) in this patent specification, including the claims in the appendix, are to be understood as being modified in all cases by the term "approximately," regardless of whether "approximately" actually precedes the numerical value or not. "Approximately" means that the stated numerical value permits a slight inaccuracy (with some approximation to the accuracy of the value, approximately or quite close to the value, almost).If the imprecision indicated by "approximately" is not otherwise understood in the field with this ordinary meaning, then "approximately," as used herein, denotes at least variations that may result from ordinary procedures for measuring and using such parameters. For example, "approximately" may include a deviation 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 certain aspects, optionally less than or equal to 0.1%.

[0039] Additionally, the disclosure of ranges includes the disclosure of all values ​​and further subdivided ranges within the entire range, including the endpoints and the sub-ranges specified for the ranges.

[0040] Exemplary embodiments are now described in more detail with reference to the attached drawings. General function, structure and composition of electrochemical cells

[0041] A typical electrochemical cell comprises a first electrode, such as a positive electrode or cathode; a second electrode, such as a negative electrode or anode; an electrolyte; and a separator. Often, in a lithium-ion battery pack, the electrochemical cells are electrically connected to form a stack to increase overall power. Electrochemical lithium-ion cells function by the reversible movement of lithium ions between the negative and positive electrodes. The separator and electrolyte are located between the negative and positive electrodes. The electrolyte is suitable for conducting lithium ions and can be in liquid, gel, or solid form. The lithium ions move from a positive electrode to a negative electrode during charging and in the opposite direction during discharging.

[0042] Each of the negative and positive electrodes within a battery stack is typically electrically connected to a current collector (e.g., a metal such as copper for the negative electrode and aluminum for the positive electrode). During battery operation, the current collectors of the two electrodes are connected by an external circuit that allows the electron-generated current to flow between the negative and positive electrodes to balance the transport of lithium ions.

[0043] The electrodes can generally be incorporated into various commercially available battery forms, such as prismatic cells, wound cylindrical cells, button cells, pouch cells, or other suitable cell shapes. The cells can comprise a single electrode structure of each polarity or a stacked structure with multiple positive and negative electrodes arranged in parallel and / or series electrical connections. Specifically, the battery can comprise a stack of alternating positive and negative electrodes with separators between them. While the positive electroactive materials in batteries can be used for primary or single-use applications, the resulting batteries generally exhibit desirable cycling characteristics for secondary use through multiple cell cycles.

[0044] An exemplary schematic illustration of a 100 mAh lithium-ion battery is shown in Fig. Figure 1 shows the lithium-ion battery 100 comprising a negative electrode 102, a positive electrode 104, and a porous separator 106 (e.g., a microporous or nanoporous polymeric separator) arranged between the negative and positive electrodes 102 and 104. An electrolyte 110 is located between the negative and positive electrodes 102 and 104 and in pores of the porous separator 106. The electrolyte 110 may also be present in the negative electrode 102 and positive electrode 104, for example, in pores.

[0045] A current collector 112 of the negative electrode can be positioned on or near the negative electrode 102. A current collector 114 of the positive electrode can be positioned on or near the positive electrode 104. Although not shown, the current collector 112 of the negative electrode and the current collector 114 of the positive electrode can be coated on one or both sides, as is known in the art. In certain aspects, the current collectors can be coated on both sides with an electroactive layer. The current collector 112 of the negative electrode and the current collector 114 of the positive electrode each capture free electrons and move them to and from an external circuit 120.The interruptible external circuit 120 comprises a load device 122 which connects the negative electrode 102 (via the current collector 112 of the negative electrode) and the positive electrode 104 (via the current collector 114 of the positive electrode).

[0046] The porous separator 106 functions as both an electrical insulator and a mechanical support. Specifically, the porous separator 106 is positioned between the negative electrode 102 and the positive electrode 104 to prevent or reduce physical contact and thus the occurrence of a short circuit. The porous separator 106 not only provides a physical barrier between the two electrodes 102 and 104, but can also provide a minimal resistance path for the internal passage of lithium ions (and related anions) during lithium-ion cycling, thereby facilitating the operation of the lithium-ion battery 100.

[0047] The lithium-ion battery 100 can generate an electric current during discharge through reversible electrochemical reactions that occur when the external circuit 120 is closed (to electrically connect the negative electrode 102 and the positive electrode 104) and the negative electrode 102 contains a relatively larger amount of cyclable lithium. The difference in chemical potential between the positive electrode 104 and the negative electrode 102 drives the electrons produced by the oxidation of lithium (e.g., intercalated / alloyed / plated lithium) at the negative electrode 102 through the external circuit 120 toward the positive electrode 104. The lithium ions, also produced at the negative electrode, are simultaneously transferred through the electrolyte 110 and the porous separator 106 toward the positive electrode 104.The electrons flow through the external circuit 120 and the lithium ions migrate through the porous separator 106 into the electrolyte 110 to intercalate / alloy / plate into a positive electroactive material of the positive electrode 104. The electric current flowing through the external circuit 120 can be utilized and directed by the load device 122 until the lithium in the negative electrode 102 is consumed and the capacity of the lithium-ion battery 100 is reduced.

[0048] The lithium-ion battery 100 can be charged or re-energized at any time by connecting an external power source (e.g., a charging device) to it, thus reversing the electrochemical reactions that occur during battery discharge. Connecting an external power source to the lithium-ion battery 100 forces the lithium ions at the positive electrode 104 to move back towards the negative electrode 102. The electrons flowing back towards the negative electrode 102 through the external circuit 120, and the lithium ions carried back towards the negative electrode 102 by the electrolyte 110 through the separator 106, recombine at the negative electrode 102 and replenish the lithium for use in the next battery discharge cycle.Thus, each discharge and charge event is considered a cycle in which lithium ions are cycled between the positive electrode 104 and the negative electrode 102.

[0049] The external power source used to charge the 100-cell lithium-ion battery can vary depending on its size, design, and intended application. Some examples of suitable external power sources include AC power sources such as a wall outlet or a vehicle alternator. An inverter can be used to convert the AC power to DC for charging the 100-cell battery.

[0050] In many lithium-ion battery configurations, the negative electrode current collector 112, the negative electrode 102, the separator 106, the positive electrode 104, and the positive electrode current collector 114 are each manufactured as relatively thin layers (for example, with a thickness of a few micrometers up to one millimeter or less) and assembled in electrical series and / or parallel layers to provide a suitable package for electrical energy and current. Furthermore, the lithium-ion battery 100 may include a variety of other components which, although not shown herein, are nevertheless known to those skilled in the art.For example, the lithium-ion battery 100 may include a casing, seals, terminal caps, tabs, battery posts, and any other conventional components or materials that may be located within the battery 100, including, but not limited to, between or around the negative electrode 102, the positive electrode 104, and / or the separator 106. As mentioned above, the size and shape of the lithium-ion battery 100 may vary depending on the specific application for which it is designed. Battery-powered vehicles and portable consumer electronics devices are two examples where the lithium-ion battery 100 would very likely be designed to different size, capacity, and performance specifications.The lithium-ion battery 100 can also be connected in series or parallel with other similar lithium-ion cells or batteries to produce a higher output voltage, energy and power if required for the load device 122.

[0051] Accordingly, the lithium-ion battery 100 can generate electrical current for a load device 122, which can be operatively connected to the external circuit 120. Although the load device 122 can be a number of known electrically powered devices, some particular examples of power-consuming load devices include, but are not limited to, an electric motor for a hybrid or fully electric vehicle, a laptop computer, a tablet computer, a mobile phone, and cordless power tools or devices. The load device 122 can also be a power-generating device that charges the lithium-ion battery 100 for the purpose of energy storage. In certain other variations, the electrochemical cell can be a supercapacitor, such as a lithium-ion-based supercapacitor. electrolyte

[0052] Any suitable electrolyte 110, whether in solid, liquid, or gel form, capable of conducting lithium ions between the negative electrode 102 and the positive electrode 104, can be used in the lithium-ion battery 100. In certain aspects, the electrolyte 110 can be a non-aqueous liquid electrolyte solution comprising a lithium salt dissolved in an organic solvent or a mixture of organic solvents. Numerous conventional non-aqueous liquid electrolyte solutions 110 can be used in the lithium-ion battery 100. In certain variations, the electrolyte 110 can comprise an aqueous solvent (i.e., a water-based solvent) or a hybrid solvent (e.g., an organic solvent containing at least 1% water by weight).

[0053] Suitable lithium salts generally have inert anions. Non-restrictive examples of lithium salts that can be dissolved in an organic solvent to form the non-aqueous liquid electrolyte solution include lithium hexafluorophosphate (LiPF6); lithium perchlorate (LiClO4); lithium tetrachloroaluminate (LiAlCl4); lithium iodide (LiI); lithium bromide (LiBr); lithium thiocyanate (LiSCN); lithium tetrafluoroborate (LiBF4); lithium difluorooxalatoborate (LiBF2(C2O4)) (LiODFB); lithium tetraphenylborate (LiB(C6H5)4); lithium bis-(oxalate)borate (LiB(C2O4)2) (LiBOB); lithium tetrafluorooxalatophosphate (LiPF4(C2O4)) (LiFOP); lithium nitrate (LiNO3); lithium hexafluoroarsenate (LiAsF6); and lithium trifluoromethanesulfonate (LiCF3SO3). Lithium bis(trifluoromethanesulfonimide) (LITFSI) (LiN(CF3SO2)2); lithium fluorosulfonylimide (LiN(FSO2)2) (LIFSI); and combinations thereof. In certain variations, electrolyte 110 can contain a concentration of 1 M of the lithium salts.

[0054] These lithium salts can be dissolved in a variety of organic solvents, such as organic ethers or organic carbonates. Organic ethers can include dimethyl ethers, glymes (glycol dimethyl ether or dimethoxyethane (DME, such as 1,2-dimethoxyethane)), diglymes (diethylene glycol dimethyl ether or bis(2-methoxyethyl) ether), triglymes (tri(ethylene glycol) dimethyl ether), ethers with additional chain structures such as 1,2-diethoxyethane, ethoxymethoxyethane, 1,3-dimethoxypropane (DMP), cyclic ethers such as tetrahydrofuran, 2-methyltetrahydrofuran, and combinations thereof. In certain variations, the organic ether compound is selected from the group consisting of: Tetrahydrofuran, 2-Methyl-tetrahydrofuran, Dioxolane, Dimethoxyethane (DME), Diglyme (Diethylene Glycol Dimethyl Ether), Triglyme (Tri(ethylene Glycol) Dimethyl Ether), 1,3-Dimethoxypropane (DMP), and combinations thereof.Carbonate-based solvents can include various alkyl carbonates, such as cyclic carbonates (e.g., ethylene, propylene, and butylene carbonate) and acyclic carbonates (e.g., dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate (EMC)). Ether-based solvents include cyclic ethers (e.g., tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane) and chain ethers (e.g., 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane).

[0055] In various aspects, suitable solvents can be selected from propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, γ-butyrolactone, dimethyl sulfoxide, acetonitrile, nitromethane and mixtures thereof, in addition to those described above.

[0056] If the electrolyte is a solid-state electrolyte, it may comprise a composition selected from the group consisting of LiTi2(PO4)3, LiGe2(PO4)3, Li7La3Zr2O 12 , Li3xLa2 / 3 -xTiO3, Li3PO4, Li3N, Li4GeS4, Li 10 GeP2S 12 , Li2S-P2S5, Li6PS5Cl, Li6PS5Br, Li6PS5I, Li3OCl, Li 2,99 Ba 0,005 ClO, or a combination thereof. Porous separator

[0057] The porous separator 106 can, in certain variations, comprise a microporous polymeric separator containing a polyolefin, including those made from a homopolymer (derived from a single monomer component) or a heteropolymer (derived from more than one monomer component), which may be either linear or branched. Depending on the specific aspect, the polyolefin may be polyethylene (PE), polypropylene (PP), a blend of PE and PP, or multilayer structured porous films of PE and / or PP. Commercially available membranes for porous polyolefin separators 106 include CELGARD® 2500 (single-layer polypropylene separator) and CELGARD® 2340 (three-layer polypropylene / polyethylene / polypropylene separator), offered by Celgard LLC.

[0058] If the porous separator 106 is a microporous polymer separator, it can be a single layer or a multilayer laminate. For example, in one embodiment, a single layer of the polyolefin can form the entire microporous polymer separator 106. In other embodiments, the separator 106 can be a fibrous membrane exhibiting a multitude of pores extending between opposing surfaces and having, for example, a thickness of less than one millimeter. As another example, several discrete layers of identical or different polyolefins can be combined to form the microporous polymer separator 106.The microporous polymer separator 106 can alternatively or additionally include other polymers besides polyolefin, such as, but not limited to, polyethylene terephthalate (PET), polyvinylidene fluoride (PVDF), polyamide (nylon), polyurethanes, polycarbonates, polyesters, polyetheretherketones (PEEK), polyethersulfones (PES), polyimides (PI), polyamideimides, polyethers, polyoxymethylene (e.g., acetal), polybutylene terephthalate, polyethylene naphthenate, polybutene, polymethylpentene, polyolefin copolymers, acrylonitrile butadiene styrene copolymers (ABS), polystyrene copolymers, polymethyl methacrylate (PMMA), polysiloxane polymers (e.g., polydimethylsiloxane (PDMS)), polybenzimidazole (PBI), polybenzoxazole (PBO), polyphenylenes, polyaryleneetherketones, polyperfluorocyclobutanes, and polyvinylidene fluoride copolymers. (e.g. PVDF-hexafluoropropylene or (PVDF-HFP)) and polyvinylidene fluoride terpolymers, polyvinyl fluoride, liquid crystalline polymers (e.g. VECTRAN. TM(Hoechst AG, Germany) and ZENITE® (DuPont, Wilmington, DE)), polyaramides, polyphenylene oxide, cellulose materials, mesoporous silicon dioxide, or combinations thereof.

[0059] Furthermore, the porous polymer separator 106 can be mixed with a ceramic material or its surface can be coated with a ceramic material. For example, a ceramic coating can comprise aluminum oxide (Al₂O₃), silicon dioxide (SiO₂), or combinations thereof. Various conventionally available polymers and commercially available products can be used to form the separator 106, and numerous manufacturing processes can be employed to produce such a microporous polymer separator 106. solid electrolyte

[0060] In various aspects, the porous separator 106 and the electrolyte 110 can be replaced by a solid electrolyte (SSE) that functions as both an electrolyte and a separator. The SSE can be positioned between a positive and a negative electrode. The SSE facilitates the transfer of lithium ions while simultaneously providing mechanical separation and electrical insulation between the negative and positive electrodes 102, 104. As a non-restrictive example, SSEs can be LiTi2(PO4)3, Li 1,3 Al 0,3 Ti 1,7 (PO4)3 (LATP), LiGe2(PO4)3, Li7La3Zr2O 12 , Li3xLa 2 / 3 -xTiO3, Li3PO4, Li3N, Li4GeS4, Li 10 GeP2S 12 , Li2S-P2S5, Li6PS5Cl, Li6PS5Br, Li6PS5I, Li3OCl, Li 2,99 Ba 0,005 ClO, or combinations thereof. Positive electrode

[0061] The positive electrode 104 can be formed from or comprise a lithium-based active material that can undergo lithium intercalation and deintercalation, alloying and dealloying, or coating and stripping while acting as the positive terminal of the lithium-ion battery 100. The positive electrode 104 can comprise a positive electroactive material. Positive electroactive materials can include one or more transition metal cations, such as manganese (Mn), nickel (Ni), cobalt (Co), chromium (Cr), iron (Fe), vanadium (V), and combinations thereof. In certain variations, however, the positive electrode 104 is essentially free of selected metal cations, such as nickel (Ni) and cobalt (Co).

[0062] Two exemplary common classes of known electroactive materials that can be used to form the positive electrode 104 are layered lithium transition metal oxides and spinel-phase lithium transition metal oxides. In certain cases, the positive electrode 104 can, for example, be a spinel-like transition metal oxide such as lithium manganese oxide (Li₂M₆). (1+x) Mn (2-x) O4) include, where x is typically < 0.15, including LiMn2O4 (LMO) and lithium manganese nickel oxide LiMn 1,5 Ni 0,5 O4 (LMNO). In other cases, the positive electrode can consist of 104 layered materials such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), a lithium nickel manganese cobalt oxide (Li(Ni) x Mn y Co z )O2) include, where 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, 0 ≤ z ≤ 1, and x+y+z=1 (e.g. LiNi) 0,6 Mn 0,2 Co 0,2 O2, LiNi 0,8 Mn 0,1 Co 0,1 O2, and / or LiMn 0,33 Ni0,33 Co 0,33 O2) , a lithium nickel cobalt metal oxide (LiNi (1-x-y) Co x M y O2), where 0 < x < 1, 0 < y < 1 and M can be Al, Mn, or the like. Other known lithium transition metal compounds such as lithium iron phosphate (LiFePO4) or lithium iron fluorophosphate (Li2FePO4F) can also be used. In certain aspects, the positive electrode 104 can comprise an electroactive material containing manganese, such as lithium manganese oxide (Li2FePO4). (1+x) Mn (2-x) O4), a mixed lithium manganese nickel oxide (LiMn (2-x) Ni x O4), where 0 ≤ x ≤ 1, and / or a lithium manganese nickel cobalt oxide (e.g. LiNi 0,6 Mn 0,2 Co 0,2 O2, LiNi 0,8 Mn 0,1 Co 0,1 O2, and / or LiMn 0,33 Ni 0,33 Co 0,33O2). In a lithium-sulfur battery, the positive electrodes can contain elemental sulfur as the active material or a sulfur-containing active material.

[0063] The positive electroactive materials can be powder compositions. These materials can be mixed with an optional electrically conductive material (e.g., electrically conductive particles) and a polymeric binder. The binder can both bind the positive electroactive material together and impart ionic conductivity to the positive electrode.The polymeric binder may include polyvinylidene fluoride (PVdF), poly(vinylidene chloride) (PVC), poly((dichloro-1,4-phenylene)ethylene), carboxymethoxylcellulose (CMC), nitrile butadiene rubber (NBR), fluorinated urethanes, fluorinated epoxides, fluorinated acrylates, copolymers of halogenated hydrocarbon polymers, epoxides, ethylene propylene diamine termonomer rubber (EPDM), hexafluoropropylene (HFP), ethylene acrylic acid copolymer (EAA), ethylene vinyl acetate copolymer (EVA), EAA / EVA copolymers, PVDF / HFP copolymers, polyvinylidene difluoride (PVdF), lithium polyacrylate (LiPAA), sodium polyacrylate (NaPAA), sodium alginate, lithium alginate, or combinations thereof.

[0064] The loading of positive electroactive material in the binder can be high, such as greater than approximately 80 wt.%. For example, the binder can be present at a level greater than or equal to approximately 1 wt.% to less than or equal to approximately 20 wt.%, optionally greater than or equal to approximately 1 wt.% to less than or equal to approximately 10 wt.%, optionally greater than or equal to approximately 1 wt.% to less than or equal to approximately 8 wt.%, optionally greater than or equal to approximately 1 wt.% to less than or equal to approximately 6 wt.%, optionally greater than or equal to approximately 1 wt.% to less than or equal to approximately 7 wt.%, optionally greater than or equal to approximately 1 wt.% to less than or equal to approximately 5 wt.%, or optionally greater than or equal to approximately 1 wt.% to less than or equal to approximately 3 wt.%.

[0065] Electrically conductive materials can include graphite, other carbon-based materials, conductive metals, or conductive polymer particles. Carbon-based materials can be, as a non-restrictive example, particles from KET-JEN. TM Black, THINK TM Examples include black, acetylene black, carbon black, and the like. Conductive metal particles can include nickel, gold, silver, copper, aluminum, and the like. Examples of conductive polymers include polyaniline, polythiophene, polyacetylene, polypyrrole, and the like. In certain applications, mixtures of electrically conductive materials can be used.

[0066] In certain variations, the positive electrode 104 comprises the electrically conductive material in an amount of less than or equal to approximately 15 wt.%, optionally less than or equal to approximately 10 wt.%, or optionally greater than or equal to approximately 0.5 wt.% to less than or equal to approximately 8 wt.%. Although the additional electrically conductive compositions can be described as powders, these materials lose their powder-like character after incorporation into the electrode, with the associated particles of the additional electrically conductive materials becoming a component of the resulting electrode structure. Negative electrode

[0067] The negative electrode 102 can comprise a negatively electroactive material as a lithium host material, which can function as the negative pole of the lithium-ion battery 100. Commonly used negative electroactive materials include lithium insertion materials or alloy host materials. Such materials can be carbon-based, such as lithium-graphite intercalation compounds, lithium-silicon compounds, lithium-tin alloys, or lithium titanate (Li). 4+x Ti5O 12 , where 0 ≤ x ≤ 3, such as Li4Ti5O 12 (LTO).

[0068] In certain aspects, the negative electrode 102 can comprise lithium, and in certain variations, also metallic lithium and the lithium-ion battery 100. The negative electrode 102 can be a lithium metal electrode (LME). The lithium-ion battery 100 can be a lithium metal battery or cell. Metallic lithium for use in the negative electrode of a rechargeable battery has several potential advantages, including the highest theoretical capacity and the lowest electrochemical potential. Thus, batteries with lithium metal anodes can have a higher energy density, potentially doubling the storage capacity, so the battery is only half the size but has the same lifespan as other lithium-ion batteries.

[0069] In certain variations, the negative electrode 102 may optionally comprise an electrically conductive material and one or more polymeric binders to structurally hold the lithium material together. In one embodiment, for example, the negative electrode 102 may comprise an active material comprising lithium metal particles mixed with a binder material selected from the group consisting of: polyvinylidene fluoride (PVdF), ethylene propylene diene monomer rubber (EPDM), carboxymethoxylcellulose (CMC), nitrile butadiene rubber (NBR), lithium polyacrylate (LiPAA), sodium polyacrylate (NaPAA), sodium alginate, lithium alginate, or a combination thereof. Suitable additional electrically conductive materials may be carbon-based materials or a conductive polymer. Carbon-based materials may, for example (but not limited to), be particles from KETJEN TM -Black, THINK TM-Black, acetylene black, carbon black, and the like. Examples of conductive polymers include polyaniline, polythiophene, polyacetylene, polypyrrole, and the like. In certain cases, mixtures of conductive materials may also be used. The negative electrode 102 may comprise approximately 50–100 wt.% of an electroactive material (e.g., lithium particles or a lithium foil), optionally greater than or equal to approximately 30 wt.% of an electrically conductive material, and a binder as the remainder. Electrode manufacturing

[0070] In various aspects, the negative and positive electrodes 102 and 104 can be prepared by mixing the respective electroactive material into a slurry with a polymeric binder compound, a non-aqueous solvent, optionally a plasticizer, and, if necessary, electrically conductive particles. The slurry can be mixed or stirred and then applied thinly to a substrate using a doctor blade and / or a slot nozzle coating. The substrate can be a removable substrate or, alternatively, a functional substrate, such as a current collector (e.g., a metallic grid or mesh layer) attached to one side of the electrode film. In a modification, heat or radiation can be applied to evaporate the solvent from the electrode film, leaving a solid residue.The electrode film can be further solidified by applying heat and pressure to sinter and calender it. In other variations, the film can be dried at a moderate temperature to form self-supporting films. If the substrate is removable, it is removed from the electrode film, which is then laminated onto a current collector. With both types of substrates, any remaining plasticizer can be extracted before installation in the battery cell. A solid electrode can also be formed using alternative manufacturing processes. Optional electrode surface coatings

[0071] In certain variations, prefabricated negative electrodes 102 and positive electrodes 104 formed by the above-described slurry casting of active material can be directly coated by a vapor coating formation process to form a conformal inorganic-organic composite surface coating, as described below.

[0072] Thus, one or more exposed areas of the prefabricated negative electrodes, which contain the electroactive material, can be coated to minimize or prevent the reaction of the electrode materials with components within the electrochemical cell, and to minimize or prevent the formation of lithium metal dendrites on the surfaces of the negative electrode materials when they are incorporated into the electrochemical cell. In other variations, a variety of particles containing an electroactive material such as lithium metal can be coated with an inorganic-organic composite surface coating. The coated electroactive particles can then be used in the active material slurry to form the negative electrode, as described above. Power collectors

[0073] The negative and positive electrodes 102, 104 are generally assigned current collectors 112, 114 to facilitate the flow of electrons between the electrode and the external circuit 120. The current collectors 112, 114 are electrically conductive and may comprise metal, such as a metal foil, a metal grid or screen, or expanded metal. Expanded metal current collectors are metal grids with a greater thickness, so that a larger amount of electrode material is placed within the metal grid. As a non-restrictive example, electrically conductive materials include copper, nickel, aluminum, stainless steel, titanium, gold, alloys thereof, or combinations thereof.

[0074] The current collector 114 of the positive electrode can be made of aluminum or another suitable electrically conductive material known to those skilled in the art. The current collector 112 of the negative electrode can be made of copper or another suitable electrically conductive material known to those skilled in the art. Current collectors of the negative electrode generally do not include aluminum, as aluminum reacts with lithium, causing significant expansion and contraction. These drastic volume changes can lead to breakage and / or pulverization of the current collector. Analysis of electrochemical cells

[0075] It can be desirable to perform electrochemical analyses on electrodes. Electrochemical analysis can produce calibrations for control systems in HEVs and EVs, relating, for example, to fast charging, lithium plating, state of charge, and power estimation. The electrodes can be analyzed by creating a reference electrode in an electrochemical cell that includes positive and negative electrodes. The reference electrode allows monitoring of individual positive and negative electrode potentials while the cell is cycled. The potentials can be monitored in a laboratory environment or during real-time operation of a system that includes the electrochemical cell. For example, potentials can be detected during vehicle operation as part of routine vehicle diagnostics.Detected potentials can be used in vehicle control algorithms to improve cell performance, such as by raising the anode potential to reduce lithium plating.

[0076] Some reference electrodes are non-porous and can therefore create a "shadow effect" during cell cycling by blocking ion transport in the reference electrode area and thus impairing cell performance. Another type of reference electrode, which can be described as a "point-shaped reference electrode," is porous and relatively small. Electrochemical cells that include point-shaped reference electrodes can experience a reduced cycle life and uneven current distribution, potentially leading to cell damage such as lithium plating.

[0077] In various aspects, the present disclosure provides a reference electrode arrangement comprising a separator substrate and a reference electrode layer in direct contact with the separator substrate. The reference electrode layer comprises an electroactive material mixed with an electrically conductive material. The electrically conductive material can form a conductive network throughout the reference electrode layer, thus acting as a current collector. The reference electrode arrangement can therefore be free of a separate current collector layer. The reference electrode layer can be a single layer (e.g., a monolayer). The present disclosure also provides an electrochemical cell comprising a reference electrode arrangement. The reference electrode arrangement can be used for highly accurate in-situ potential measurement of individual negative and positive electrodes in the electrochemical cell.

[0078] The present disclosure also provides methods for manufacturing a reference electrode assembly. These methods may include the formation of the reference electrode layer in a KISS engraving coating process. Compared to a multilayer reference electrode assembly, such as one comprising a separate current collector, the present reference electrode assembly may exhibit reduced manufacturing complexity in certain aspects. For example, the reference electrode may be manufactured in a single coating process.

[0079] With reference to Fig. In 2A-2B, an electrochemical device or cell 200 is provided according to various aspects of the present disclosure. The electrochemical device 200 comprises a first or negative electrode 202 and a second or positive electrode 204. The negative electrode 202 is coupled to a current collector 206 of the negative electrode. The positive electrode 204 is electrically connected to a current collector 208 of the positive electrode.

[0080] A reference electrode assembly or component 210 and a separator component 212 are arranged between the negative and positive electrodes 202, 204. The negative and positive electrodes 202, 204, the reference electrode assembly 210, and the separator component 212 can be saturated with an electrolyte (not shown). The separator component 212 can be arranged between the positive electrode 204 and the reference electrode assembly 210.

[0081] The reference electrode arrangement 210 comprises a reference electrode layer or film 214 (also referred to as an "electroactive layer or film") and a separator substrate or separator layer or a reference electrode separator 216. In at least one exemplary embodiment, the reference electrode arrangement 210 is oriented in the electrochemical device 200 such that the separator substrate 216 is located next to the negative electrode 202 and the reference electrode layer 214 is located next to the separator component 212. The reference electrode layer can be located directly between the separator component 212 and the separator substrate 216. The separator substrate 216 can be located directly between the negative electrode 202 and the reference electrode layer 214.In at least one other exemplary embodiment, an electrochemical device can be arranged such that a separator layer is arranged next to a positive electrode and an electroactive layer is arranged next to a separator component.

[0082] In at least one exemplary embodiment, the reference electrode arrangement 210 can have a similar size and shape to the negative and positive electrodes 202, 204. For example, the reference electrode arrangement 210, the negative electrode 202, and the positive electrode 204 can all have a common first dimension or width 220 and a second dimension or height 222. The reference electrode layer 214 can also have the same width 220 and height 222 as the negative and positive electrodes 202, 204.

[0083] With reference to Fig. 2B A first measuring device, such as a first voltage measuring device 230, can be electrically connected to the negative and positive electrodes 202, 204 via the current collectors 206, 208 of the negative and positive electrodes in order to detect a potential between the negative and positive electrodes 202, 204. A second measuring device, such as a second voltage measuring device 232, can be electrically connected to the negative electrode 202 and the reference electrode layer 214 via the current collectors 206 of the negative electrode and the reference electrode layer 214 in order to detect a potential difference between the negative electrode 202 and the reference electrode layer 214.

[0084] An electrical conductor for the second voltage measuring device 232 can be connected at any accessible point on the reference electrode layer 214 without the need for a separate tab, since the conductive network extends throughout the entire reference electrode layer 214. Because the properties of the reference electrode layer 214 are known, the measurement by the second voltage measuring device 232 ultimately provides the individual potential of the negative electrode 202. The individual potential of the positive electrode 204 can be determined from the preceding measurements. In at least one exemplary embodiment, the electrochemical device comprising the reference electrode arrangement 210 is used for in-situ electrode potential measurement.

[0085] With reference to Fig. 3. The reference electrode layer 214 can be in direct contact with the separator substrate 216. In at least one exemplary embodiment, the reference electrode layer 214 is in the form of a single layer. As used herein, the term "single layer" means a layer that has substantially the same composition over its entire thickness. The single layer comprises a mixture of materials. The materials are not present as separate multiple layers, but are mixed together over the entire thickness of the single layer, as discussed further below in the section on Fig. 4 is described in more detail. In at least one exemplary embodiment, as in Fig. As shown in Figure 4, the single layer is a monolayer. As used herein, the term "monolayer" refers to a single layer with a thickness of one particle of electroactive material. Thus, the thickness of the monolayer is essentially equal to the diameter of the particles of electroactive material.

[0086] In at least one exemplary embodiment, the reference electrode arrangement 210 is free of a separate electrically conductive layer (e.g., a current collector). The reference electrode arrangement 210 can be free of a separate current collector if an electrically conductive material is present in the reference electrode layer 214 in such an amount and / or format that it forms an electrically conductive network throughout the entire reference electrode layer 214. The network can extend over the entire length, width, and thickness of the reference electrode layer 214.

[0087] In at least one other exemplary embodiment, a reference electrode arrangement further comprises one or more electrically conductive layers. An electrically conductive layer can be present on both sides of a reference electrode layer (i.e., such that the electrically conductive layer is located between a separator substrate and a reference electrode layer, or such that a reference electrode layer is located between a separator substrate and an electrically conductive layer). The electrically conductive layer can comprise a carbon-based material, a carbon fiber, a carbon nanotube, graphene, gold, aluminum, platinum, copper, a composite thereof, or a combination thereof.

[0088] In at least one exemplary embodiment, the reference electrode layer 214 covers all or a substantial portion of a region of the entire surface area 300 of the separator substrate 216. As used herein, the term "surface area" refers to an outermost or uppermost surface. The "surface area" is smaller than the actual area, which also includes portions of the surface defining pores that are located away from the outermost or uppermost surface. In at least one exemplary embodiment, the reference electrode layer 214 covers substantially the entire area of ​​the surface area 300 of the separator substrate 216. Thus, the surface area 216 is substantially free of uncoated portions.Pore ​​surfaces of the separator substrate 300 that are not part of the surface area 300 can be essentially uncoated or free from direct contact with the reference electrode layer 214. This means that the electroactive material 400 generally does not extend into the pores and clog them.

[0089] In at least one exemplary embodiment, the reference electrode layer 214 covers approximately 50% or more of the total surface area 300 of the separator substrate 216 (e.g., approximately 55% or more, approximately 60% or more, approximately 65% ​​or more, approximately 70% or more, approximately 75% or more, approximately 80% or more, approximately 85% or more, approximately 90% or more, approximately 92% or more, approximately 95% or more, approximately 96% or more, approximately 97% or more, approximately 98% or more, or approximately 99%). In at least one exemplary embodiment, the reference electrode layer 214 covers less than 100% or more of the surface area 300 of the separator substrate 216 (e.g.,less than or equal to approximately 99%, less than or equal to approximately 98%, less than or equal to approximately 97%, less than or equal to approximately 96%, less than or equal to approximately 95%, less than or equal to approximately 92%, less than or equal to approximately 90%, less than or equal to approximately 85%, less than or equal to approximately 80%, less than or equal to approximately 75%, less than or equal to approximately 70%, less than or equal to approximately 65%, less than or equal to approximately 60%, or less than or equal to approximately 55%).

[0090] The reference electrode arrangement 210 is porous, allowing ions to pass through it during the cycling of the electrochemical device 200. In at least one exemplary embodiment, the reference electrode arrangement 210 has a total porosity of approximately 30% or greater than or equal to approximately 35% (e.g., approximately 40% or greater than or equal to approximately 45%, approximately 50%, approximately 55%, approximately 60%, approximately 65%, approximately 70%, or approximately 75%). The reference electrode arrangement 210 can have a total porosity of less than approximately 80% (e.g.,less than or equal to approximately 75%, less than or equal to approximately 70%, less than or equal to approximately 65%, less than or equal to approximately 60%, less than or equal to approximately 55%, less than or equal to approximately 50%, less than or equal to approximately 45%, less than or equal to approximately 40%, or less than or equal to approximately 35%.

[0091] In at least one exemplary embodiment, the reference electrode arrangement 214 has a first porosity of approximately 30% or greater than or equal to 35% (e.g., approximately 40% or greater than or equal to 45%, approximately 50% or greater than or equal to 55%, approximately 60% or greater than or equal to 65%, approximately 70% or greater than or equal to 75%). The first porosity of the reference electrode layer 214 can be approximately 80% or less than or equal to 80% (e.g., approximately 75% or less than or equal to 70%, approximately 65% ​​or less than or equal to 60%, approximately 55% or less than or equal to 50%, approximately 45% or less than or equal to 40%, or approximately 35%).In at least one exemplary embodiment, the separator substrate 216 has a second porosity of approximately 30% or greater than or equal to 35% (e.g., approximately 40% or greater than or equal to 45%, approximately 50% or greater than or equal to 55%, approximately 60% or greater than or equal to 65%, approximately 70% or greater than or equal to 75%). The second porosity of the separator substrate 216 can be approximately 80% or less than 80% (e.g., approximately 75% or less than or equal to 70%, approximately 65% ​​or less than or equal to 60%, approximately 55%, approximately 50%, approximately 45%, approximately 40%, or approximately 35%).In at least one exemplary embodiment, the first porosity is greater than or equal to the second porosity, such that the reference electrode layer 214 does not impede the passage of ions through the reference electrode arrangement 210. In at least one exemplary embodiment, the first and second porosities are equal.

[0092] In at least one exemplary embodiment, the reference electrode layer 214 defines a first thickness 302. The first thickness 302 is greater than or equal to approximately 0.1 micrometers (µm) (e.g., greater than or equal to approximately 0.2 µm, greater than or equal to approximately 0.3 µm, greater than or equal to approximately 0.4 µm, greater than or equal to approximately 0.5 µm, greater than or equal to approximately 0.75 µm, greater than or equal to approximately 1 µm, greater than or equal to approximately 1.5 µm, greater than or equal to approximately 2 µm, greater than or equal to approximately 2.5 µm, greater than or equal to approximately 3 µm, greater than or equal to approximately 3.5 µm, greater than or equal to approximately 4 µm, greater than or equal to approximately 4.5 µm, greater than or equal to approximately 5 µm, greater than or equal to approximately). 6 µm, greater than or equal to approximately 7 µm, greater than or equal to approximately 8 µm, or greater than or equal to approximately 9 µm). The first thickness 302 can be less than or equal to approximately 10 µm (e.g.less than or equal to approximately 9 µm, less than or equal to approximately 8 µm, less than or equal to approximately 7 µm, less than or equal to approximately 6 µm, less than or equal to approximately 5 µm, less than or equal to approximately 4.5 µm, less than or equal to approximately 4 µm, less than or equal to approximately 4 µm, less than or equal to approximately 3.5 µm, less than or equal to approximately 3 µm, less than or equal to approximately 2.5 µm, less than or equal to approximately 2 µm, less than or equal to approximately 1.5 µm, less than or equal to approximately 1 µm, less than or equal to approximately 0.75 µm, less than or equal to approximately 0.5 µm, less than or equal to approximately 0.4 µm, less than or equal to approximately 0.3 µm or less than or equal to approximately 0.2 µm).

[0093] In at least one exemplary embodiment, the separator substrate 216 defines a second thickness 304. The second thickness 304 can be greater than or equal to approximately 5 µm (e.g., greater than or equal to approximately 7.5 µm, greater than or equal to approximately 10 µm, greater than or equal to approximately 12.5 µm, greater than or equal to approximately 15 µm, greater than or equal to approximately 17.5 µm, greater than or equal to approximately 20 µm, or greater than or equal to approximately 22.2 µm). The second thickness 304 can be less than or equal to approximately 25 µm (e.g. less than or equal to approximately 22.5 µm, less than or equal to approximately 20 µm, less than or equal to approximately 17.5 µm, less than or equal to approximately 15 µm, less than or equal to approximately 12.5 µm, less than or equal to approximately 10 µm or less than or equal to approximately 7.5 µm).

[0094] In at least one exemplary embodiment, the separator substrate 216 comprises polypropylene (PP), polyethylene (PE), a ceramic material, or a combination thereof. The separator substrate 216 may comprise a single layer or multiple layers (e.g., a PP layer and a PE layer). In at least one exemplary embodiment, the separator substrate 216 comprises a coated separator (e.g., a PP and / or PE separator having a ceramic coating). In at least one exemplary embodiment, the separator substrate 216 is a solid electrolyte, such as those discussed above. A solid electrolyte may comprise a layer of electrically insulating, ionically conductive material.

[0095] In at least one exemplary embodiment, the reference electrode arrangement 210 has an air permeability of approximately 40 Gurley-sec or greater than or equal to approximately 40 Gurley-sec (e.g., approximately 50 Gurley-sec or greater than or equal to approximately 60 Gurley-sec, approximately 70 Gurley-sec or greater than or equal to approximately 80 Gurley-sec, or approximately 90 Gurley-sec or greater than or equal to approximately 90 Gurley-sec). The air permeability can be less than or equal to approximately 100 Gurley-sec (e.g., less than or equal to approximately 90 Gurley-sec, less than or equal to approximately 80 Gurley-sec, less than or equal to approximately 70 Gurley-sec, less than or equal to approximately 60 Gurley-sec, or less than or equal to approximately 50 Gurley-sec).

[0096] The term “in-plane resistance” used herein refers to the resistance of the reference electrode layer 214 when the reference electrode arrangement 210 is located in the electrochemical device 200 (shown in Fig. 2A-2B). The in-plane resistance depends partly on the size of the reference electrode layer 214. In at least one exemplary embodiment, the reference electrode layer 214 has an in-plane resistance of less than or equal to approximately 300 Ω (e.g., less than or equal to approximately 275 Ω, less than or equal to approximately 250 Ω, less than or equal to approximately 225 Ω, less than or equal to approximately 200 Ω, less than or equal to approximately 175 Ω, less than or equal to approximately 150 Ω, less than or equal to approximately 125 Ω, or less than or equal to approximately 100 Ω).

[0097] With reference to Fig. The electroactive layer 214 comprises an electroactive material 400, a binder (not shown), and an electrically conductive material 404. The electroactive material 400 and the electrically conductive material 404 are mixed and / or blended. The electrically conductive material 404 can form an electrically conductive network or mesh 406 throughout the entire electroactive layer 214. The electroactive material 400 can be located in pores 408 defined by the electrically conductive mesh 406. Essentially, the entire electroactive material 400 can be in electrical contact with the electrically conductive mesh 406. The electrically conductive network 406 can be exposed along an area 410 of the reference electrode layer 214 to facilitate the connection of electrical conductors.

[0098] In at least one exemplary embodiment, the electrically conductive material 404 in the reference electrode layer 214 can be present in a higher amount than electrically conductive additives in a positive or negative electrode to form the electrically conductive network 406. In at least one exemplary embodiment, the weight ratio between the electrically conductive material 404 and the electroactive material 400 can be greater than or equal to approximately 20:80 (e.g., greater than or equal to approximately 25:75, greater than or equal to approximately 30:70, greater than or equal to approximately 35:65, greater than or equal to approximately 40:60, greater than or equal to approximately 45:55, greater than or equal to approximately 50:50 (i.e., 1:1), greater than or equal to approximately 55:45, greater than or equal to approximately 60:40, greater than or equal to approximately 65:35, greater than or equal to approximately 70:30, or greater than or equal to approximately 75:25).The weight ratio between the electrically conductive material 404 and the electroactive material 400 can be less than or equal to approximately 80:20 (e.g., less than or equal to approximately 75:25, less than or equal to approximately 70:30, less than or equal to approximately 65:35, less than or equal to approximately 60:40, less than or equal to approximately 55:45, less than or equal to approximately 50:50 (i.e., 1:1), less than or equal to approximately 45:55, less than or equal to approximately 40:60, less than or equal to approximately 35:65, less than or equal to approximately 30:70, or less than or equal to approximately 25:75).

[0099] In at least one exemplary embodiment, the electroactive material 400 can be in the form of a plurality of particles 420. The multitude of particles 420 of the electroactive material 400 can define an average size (i.e., a diameter) greater than or equal to approximately 0.1 micrometers (µm) (e.g., greater than or equal to approximately 0.2 µm, greater than or equal to approximately 0.3 µm, greater than or equal to approximately 0.4 µm, greater than or equal to approximately 0.5 µm, greater than or equal to approximately 0.75 µm, greater than or equal to approximately 1 µm, greater than or equal to approximately 1.5 µm, greater than or equal to approximately 2 µm, greater than or equal to approximately 2.5 µm, greater than or equal to approximately 3 µm, greater than or equal to approximately 3.5 µm, greater than or equal to approximately 4 µm, or greater than or equal to approximately 4.5 µm). The average size of the multitude of particles 420 can be less than or equal to approximately 5 µm (e.g.less than or equal to approximately 4.5 µm, less than or equal to approximately 4 µm, less than or equal to approximately 4 µm, less than or equal to approximately 3.5 µm, less than or equal to approximately 3 µm, less than or equal to approximately 2.5 µm, less than or equal to approximately 2 µm, less than or equal to approximately 1.5 µm, less than or equal to approximately 1 µm, less than or equal to approximately 0.75 µm, less than or equal to approximately 0.5 µm, less than or equal to approximately 0.4 µm, less than or equal to approximately 0.3 µm, or less than or equal to approximately 0.2 µm). In at least one exemplary embodiment, the particles 420 are larger than the pores of the separator substrate 216, so that the particles 420 do not penetrate the pores.

[0100] In at least one exemplary embodiment, the reference electrode layer 214 comprises the electroactive material 400 in an amount greater than or equal to approximately 15% by weight (e.g., greater than or equal to approximately 20% by weight, greater than or equal to approximately 25% by weight, greater than or equal to approximately 30% by weight, greater than or equal to approximately 35% by weight, greater than or equal to approximately 40% by weight, greater than or equal to approximately 45% by weight, greater than or equal to approximately 50% by weight, greater than or equal to approximately 55% by weight, greater than or equal to approximately 60% by weight, greater than or equal to approximately 65% ​​by weight, or greater than or equal to approximately 70% by weight). The reference electrode layer 214 may comprise the electroactive material 400 in an amount less than or equal to approximately 80% by weight (e.g.,less than or equal to approximately 75% by weight, less than or equal to approximately 70% by weight, less than or equal to approximately 65% ​​by weight, less than or equal to approximately 60% by weight, less than or equal to approximately 55% by weight, less than or equal to approximately 50% by weight, less than or equal to approximately 45% by weight, less than or equal to approximately 40% by weight, less than or equal to approximately 35% by weight, less than or equal to approximately 30% by weight, less than or equal to approximately 25% by weight, or less than or equal to approximately 20% by weight).

[0101] The electroactive material 400 can comprise a material exhibiting a constant or substantially constant voltage regardless of the state of charge. In at least one exemplary embodiment, the electroactive material 400 can comprise lithium iron phosphate, lithium titanate, lithium aluminum, or a metal oxide, or a combination thereof.

[0102] In at least one exemplary embodiment, the electrically conductive material comprises a carbon material, gold, aluminum, platinum, copper, a composite thereof, or a combination thereof. The carbon material may comprise carbon nanotubes, carbon fibers, graphene, or a combination thereof.

[0103] In at least one exemplary embodiment, the electrically conductive material 404 can be in the form of a plurality of fibers 422 or other elongated structures. The fibers or elongated structures can have an average length greater than or equal to approximately 0.5 µm (e.g., greater than or equal to approximately 1 µm, greater than or equal to approximately 2 µm, greater than or equal to approximately 5 µm, greater than or equal to approximately 10 µm, greater than or equal to approximately 15 µm, greater than or equal to approximately 20 µm, greater than or equal to approximately 25 µm, greater than or equal to approximately 30 µm, greater than or equal to approximately 40 µm, greater than or equal to approximately 50 µm, greater than or equal to approximately 60 µm, greater than or equal to approximately 70 µm, greater than or equal to approximately 80 µm, or greater than or equal to approximately 90 µm). The average length can be less than or equal to approximately 100 µm (e.g.,less than or equal to approximately 90 µm, less than or equal to approximately 80 µm, less than or equal to approximately 70 µm, less than or equal to approximately 60 µm, less than or equal to approximately 50 µm, less than or equal to approximately 40 µm, less than or equal to approximately 30 µm, less than or equal to approximately 25 µm, less than or equal to approximately 20 µm, less than or equal to approximately 15 µm, less than or equal to approximately 10 µm, less than or equal to approximately 5 µm, less than or equal to approximately 2 µm, or less than or equal to approximately 1 µm). The 422 fibers can have an average diameter greater than or equal to approximately 1 nm (e.g.,greater than or equal to approximately 10 nm, greater than or equal to approximately 50 nm, greater than or equal to approximately 100 nm, greater than or equal to approximately 200 nm, greater than or equal to approximately 300 nm, greater than or equal to approximately 400 nm, greater than or equal to approximately 500 nm, greater than or equal to approximately 600 nm, greater than or equal to approximately 700 nm, greater than or equal to approximately 800 nm or greater than or equal to approximately 900 nm). The average diameter can be less than or equal to approximately 1 µm (e.g., less than or equal to approximately 900 nm, less than or equal to approximately 800 nm, less than or equal to approximately 700 nm, less than or equal to approximately 600 nm, less than or equal to approximately 500 nm, less than or equal to approximately 400 nm, less than or equal to approximately 300 nm, less than or equal to approximately 200 nm, less than or equal to approximately 100 nm, less than or equal to approximately 50 nm, or less than or equal to approximately 10 nm).In at least one exemplary embodiment, the reference electrode layer 214 comprises the electrically conductive material 404 in an amount greater than or equal to approximately 15% by weight (e.g., greater than or equal to approximately 20% by weight, greater than or equal to approximately 25% by weight, greater than or equal to approximately 30% by weight, greater than or equal to approximately 35% by weight, greater than or equal to approximately 40% by weight, greater than or equal to approximately 45% by weight, greater than or equal to approximately 50% by weight, greater than or equal to approximately 55% by weight, greater than or equal to approximately 60% by weight, greater than or equal to approximately 65% ​​by weight, or greater than or equal to approximately 70% by weight). The reference electrode layer 214 may comprise the electrically conductive material 404 in an amount less than or equal to approximately 80% by weight (e.g.,less than or equal to approximately 75% by weight, less than or equal to approximately 70% by weight, less than or equal to approximately 65% ​​by weight, less than or equal to approximately 60% by weight, less than or equal to approximately 55% by weight, less than or equal to approximately 50% by weight, less than or equal to approximately 45% by weight, less than or equal to approximately 40% by weight, less than or equal to approximately 35% by weight, less than or equal to approximately 30% by weight, less than or equal to approximately 25% by weight, or less than or equal to approximately 20% by weight).

[0104] The binder can be formed from materials such as those mentioned above in connection with the negative and positive electrodes 102, 104 of Fig. 1 described. In certain aspects, the binder can be a water-soluble binder. The binder can comprise carboxymethylcellulose (CMC), styrene-butadiene rubber (SBR), polyvinyl alcohol (PVA), or a combination thereof. The reference electrode layer 214 can contain the binder in an amount greater than or equal to approximately 10% by weight (e.g., greater than or equal to approximately 15% by weight or greater than or equal to approximately 20% by weight). The reference electrode layer 214 can contain the binder in an amount less than or equal to approximately 25% by weight (e.g., less than or equal to approximately 20% by weight or less than or equal to approximately 15% by weight).

[0105] In at least one exemplary embodiment, the reference electrode layer 214 has a loading of greater than or equal to approximately 1 g / m². 2 Separator substrate 216 (e.g., greater than or equal to approximately 2 g / m³)2 , greater than or equal to approximately 3 g / m² 2 , greater than or equal to approximately 4 g / m² 2 , greater than or equal to approximately 5 g / m² 2 , greater than or equal to approximately 6 g / m² 2 , greater than or equal to approximately 7 g / m² 2 , greater than or equal to approximately 8 g / m² 2 or greater than or equal to approximately 9 g / m² 2 ) on. The loading of the reference electrode layer 214 can be less than or equal to approximately 10 g / m². 2 (e.g. less than or equal to approximately 9 g / m²) 2 , less than or equal to approximately 8 g / m² 2 , less than or equal to approximately 7 g / m² 2 , less than or equal to approximately 6 g / m² 2 , less than or equal to approximately 5 g / m² 2 , less than or equal to approximately 4 g / m² 2 , less than or equal to approximately 3 g / m² 2 or less than or equal to approximately 2 g / m² 2 ) be.

[0106] In at least one exemplary embodiment, as in Fig. Figure 5 shows a method for producing a reference electrode assembly, generally comprising producing a reference electrode slurry at S500; producing an electrode precursor by coating a separator substrate with a reference electrode slurry at S504; forming a reference electrode assembly by drying the reference electrode slurry at S508; and optionally producing a plurality of reference electrode assemblies at S512.

[0107] In S500, the process involves preparing a reference electrode slurry. Preparing the reference electrode slurry involves combining a solvent, an electroactive material, a binder, and an electrically conductive material. The solvent may include water, an alcohol, N-methyl-2-pyrrolidone (NMP), or a combination thereof. The slurry may contain the solvent at a concentration greater than or equal to approximately 40% by weight (e.g.,greater than or equal to approximately 45% by weight, greater than or equal to approximately 50% by weight, greater than or equal to approximately 55% by weight, greater than or equal to approximately 60% by weight, greater than or equal to approximately 65% ​​by weight, greater than or equal to approximately 70% by weight, greater than or equal to approximately 75% by weight, greater than or equal to approximately 80% by weight, greater than or equal to approximately 85% by weight, greater than or equal to approximately 90% by weight, or greater than or equal to approximately 95% by weight). The slurry may contain the solvent at less than or equal to approximately 98% by weight (e.g.,less than or equal to approximately 95% by weight, less than or equal to approximately 90% by weight, less than or equal to approximately 85% by weight, less than or equal to approximately 80% by weight, less than or equal to approximately 75% by weight, less than or equal to approximately 70% by weight, less than or equal to approximately 65% ​​by weight, less than or equal to approximately 60% by weight, less than or equal to approximately 55% by weight, less than or equal to approximately 50% by weight, or less than or equal to approximately 45% by weight).

[0108] In S504, the process includes the fabrication of the electrode precursor. Fabrication of the electrode precursor includes the application of the reference electrode slurry to a separator substrate. The coating may be applied by KISS intaglio coating, spray coating, centrifugal coating, airflow laminate coating, a combination thereof, or other coating methods. Centrifugal coating and airflow laminate coating may be performed according to the methods described in US 11,374,268 by Gao et al., filed on September 9, 2019, and incorporated in full by reference.

[0109] As in Fig. As shown in Figure 6, the Kiss gravure coating process comprises the provision of a continuous separator substrate 600, such as from a first roller 602. The continuous separator substrate is conveyed toward a gravure roller 604. The gravure roller 604 rotates through a bath 606 comprising a reference electrode slurry. During its rotations, the gravure roller 604 picks up a layer 608 of the reference electrode slurry. In at least one exemplary embodiment, the gravure roller 604 comprises a plurality of grooves to facilitate the collection of the reference electrode slurry. The layer 608 is rotated past a doctor blade 610 to facilitate the transfer of a uniform amount of reference electrode slurry. Although Fig.Figure 6 illustrates that the gravure roller 604 rotates in the same direction as the first roller 602. In at least one other exemplary embodiment, a gravure roller rotates in a different direction than the first roller, and a doctor blade is located on the opposite side of a bath. As the gravure roller 604 continues to rotate, the layer 608 comes into contact with the separator substrate 600, and at least one section 612 is deposited onto the separator substrate 600 to form a reference electrode precursor 614.

[0110] The reference electrode precursor 614 is dried as described in more detail below and can be wound around a second roll 616. The reference electrode precursor 614 can be dried (e.g., by airflow) before being wound around the second roll 616. Steps S504 and S508 can be performed in a continuous roll-to-roll process.

[0111] In S508, the method comprises forming the reference electrode assembly by drying the reference electrode precursor. During drying, at least a portion of the solvent is removed from the slurry. In at least one exemplary embodiment, the drying comprises removing substantially all of the solvent from the reference electrode slurry. The drying can be carried out at ambient temperature (e.g., by circulation or flow of ambient air) or above ambient temperature (e.g., by circulation or flow of heated air or in an oven).

[0112] In S512, the method optionally includes the production of a plurality of reference electrode assemblies. The production of a plurality of reference electrode assemblies may involve subdividing the reference electrode formed in S508, such as when it is formed in a large-scale, continuous process. The production of the plurality of reference electrode assemblies may be accomplished by mechanical cutting (e.g., punching), laser cutting, or a combination thereof.

[0113] The foregoing description of the embodiments has been provided for illustrative and descriptive purposes. It makes no claim to be complete or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but are optionally interchangeable and may be used in a selected embodiment even if they are not specifically shown or described. They may also be modified in many ways. Such modifications are not to be considered a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] US 11,374,268

[0108]

Claims

[1] Reference electrode arrangement comprising: a separator substrate, wherein the separator substrate is porous and electrically insulating; and a reference electrode layer in direct contact with the separator substrate, wherein the reference electrode layer comprises: an electroactive material, an electrically conductive material mixed with the electroactive material, and a binding agent. [2] Reference electrode arrangement according to claim 1, wherein the reference electrode layer is in the form of a single layer. [3] Reference electrode arrangement according to claim 1, wherein the reference electrode layer is in the form of a monolayer. [4] Reference electrode arrangement according to one of the preceding claims, wherein the reference electrode arrangement is free from a separate electrically conductive layer. [5] Reference electrode arrangement according to one of the preceding claims, wherein the electrically conductive material is in the form of a plurality of electrically conductive fibers. [6] Reference electrode arrangement according to any of the preceding claims, wherein the reference electrode arrangement has a total porosity of greater than or equal to approximately 40% to less than or equal to approximately 70%. [7] Reference electrode arrangement according to any one of the preceding claims, wherein: the reference electrode layer has a thickness of approximately 0.1 micrometers to approximately 5 micrometers or greater, or The reference electrode layer defines an air permeability of greater than or equal to approximately 40 Gurley-sec to less than or equal to approximately 100 Gurley-sec. [8] Reference electrode arrangement according to one of the preceding claims, wherein the weight ratio of electrically conductive material to electroactive material in the reference electrode layer is greater than or equal to approximately 1:

1. [9] Reference electrode arrangement according to any of the preceding claims, wherein The electrically conductive material is selected from the group consisting of: carbon fibers, carbon nanotubes, graphene, gold, aluminum, platinum, copper, a composite material thereof, and combinations thereof. The electroactive material is selected from the group consisting of: lithium iron phosphate (LiFePO4), lithium titanate (Li4Ti5O4). 12 ), and combinations thereof, and The binder is selected from the group consisting of: carboxymethylcellulose, styrene-butadiene rubber, polyacrylic acid and combinations thereof, and The separator substrate comprises a material selected from the group consisting of polyethylene, polypropylene, a ceramic material and combinations thereof. [10] Reference electrode arrangement according to one of the preceding claims, wherein the reference electrode layer covers an area greater than or equal to approximately 95% of a surface area of ​​the separator substrate.

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