Electrode sheet, battery cell comprising electrode sheet, battery, and electrical device

Abstract

An electrode sheet, a battery cell comprising the electrode sheet, a battery, and an electrical device. The electrode sheet comprises a current collector and an active material layer provided on at least one surface of the current collector; per unit standard area, the mass of the current collector is a, the mass of the active material layer is b, and a and b satisfy: 0.02≤a / b≤0.3. The current collector has small internal resistance and light weight.

Description

Pole piece and battery cell, battery and electrical device containing the same

[0001] Related applications

[0002] This application claims priority to Chinese patent application number 2024204559019, filed on March 8, 2024, entitled “Pole piece and battery cell, battery and electrical device comprising the same,” the entire text of which is hereby incorporated by reference. Technical Field

[0003] The present application relates to the field of battery technology, and in particular to a pole piece and a battery cell, a battery and an electrical device comprising the pole piece. Background Art

[0004] The statements herein merely provide background information related to the present application and do not necessarily constitute prior art.

[0005] In recent years, lithium-ion batteries have been widely used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, as well as in a variety of fields such as power tools, electric bicycles, electric motorcycles, and electric vehicles. Their application range is becoming increasingly broad. As lithium-ion batteries have achieved significant development, the requirements for their performance have become increasingly personalized. In addition to traditional improvements in energy density, cycle performance, and safety, there is also a growing demand for lighter batteries.

[0006] The composite current collector includes a polymer base layer and a metal layer disposed on at least one surface of the polymer base layer. Compared to traditional pure metal current collectors, the polymer base layer is lighter, thus reducing the overall weight of the electrode. However, the introduction of the polymer base layer also increases the battery's direct current resistance (DCR), making it difficult to meet fast charging requirements.

[0007] Summary of the Invention

[0008] In order to achieve the above-mentioned objectives, the first aspect of the present application provides a pole piece with good fast charging performance and light weight, as well as a battery cell, a battery and an electrical device containing the pole piece.

[0009] In a first aspect of the present application, a pole piece is provided, comprising a current collector and an active material layer arranged on at least one surface of the current collector; within each standard area, the mass of the current collector is a, the mass of the active material layer is b, and a and b satisfy: 0.02≤a / b≤0.3.

[0010] The above-mentioned pole piece can reduce the direct current resistance (DCR) of the battery on the basis of adopting a lighter current collector such as a composite current collector, thereby achieving a lightweight design while having good fast charging performance.

[0011] In some embodiments, the mass of the current collector per standard area is 16 mg to 40 mg.

[0012] In some embodiments, the mass of the active material layer per standard area is 130 mg to 660 mg.

[0013] In some embodiments, the current collector includes a polymer material base layer and a metal layer located on at least one surface of the polymer material base layer, and the active material layer is disposed on the surface of the metal layer.

[0014] In some embodiments, per standard area, the mass of the polymer base layer is c, and the mass of the metal layer is d, where c and d satisfy the relationship: 0.1 ≤ c / d ≤ 5. Properly controlling the mass ratio of the polymer base layer to the metal layer can further reduce the internal resistance of the battery while also reducing the weight of the electrode.

[0015] In some embodiments, the mass of the polymer material base layer is 3 mg to 20 mg per standard area.

[0016] In some embodiments, the mass of the metal layer per standard area is 4 mg to 30 mg.

[0017] In some embodiments, the polymer material base layer includes a polypropylene layer, a polyethylene terephthalate layer, a polybutylene terephthalate layer, a polystyrene layer, a polyethylene layer, or a composite layer formed by laminating any two or more of the foregoing layers.

[0018] In some embodiments, the metal layer includes an aluminum layer, an aluminum alloy layer, a nickel layer, a nickel alloy layer, a titanium layer, a titanium alloy layer, a silver layer, a silver alloy layer, or a composite layer formed by stacking any two or more of the foregoing layers; or the metal layer includes a copper layer, a copper alloy layer, a nickel layer, a nickel alloy layer, a titanium layer, a titanium alloy layer, a silver layer, a silver alloy layer, or a composite layer formed by stacking any two or more of the foregoing layers.

[0019] A second aspect of the present application provides a battery cell comprising the pole piece described in the first aspect.

[0020] In some embodiments, the battery cell includes a housing for accommodating an electrode assembly, and the electrode assembly includes the electrode sheet.

[0021] In some embodiments, the shell is square in shape and includes a shell and at least one end cover, the shell has an opening at only one end, and the end cover covers the opening; or both ends of the shell have openings, and the two end covers respectively cover the two openings.

[0022] In some embodiments, the shell is a soft package structure, and the shell includes an aluminum-plastic film.

[0023] In some embodiments, the outer shell is in the shape of a cylinder, and the outer shell includes a shell and at least one end cover, the end cover covers the opening of the shell, and the outer diameter of the cylinder is greater than or equal to 30 mm.

[0024] A third aspect of the present application provides a battery comprising the battery cell described in the second aspect.

[0025] A fourth aspect of the present application provides an electrical device comprising the electrode described in the first aspect, the battery cell described in the second aspect, or the battery described in the third aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] To more clearly illustrate the technical solution of this application, the following is a brief introduction to the drawings used in this application. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without inventive effort.

[0027] FIG1 is a schematic diagram of a pole piece according to an embodiment of the present application.

[0028] FIG2 is a schematic diagram of a battery cell according to an embodiment of the present application.

[0029] FIG3 is an exploded view of the battery shown in FIG2 according to one embodiment of the present application.

[0030] FIG4 is a schematic diagram of an electrical device using a battery as a power source according to an embodiment of the present application.

[0031] Explanation of the accompanying symbols: 1. Battery; 11. Housing; 12. Electrode assembly; 13. Cover plate; 2. Electrical device.

[0032] In order to better describe and illustrate the embodiments and / or examples of the inventions disclosed herein, reference may be made to one or more of the accompanying drawings. The additional details or examples used to describe the accompanying drawings should not be considered to limit the scope of the disclosed inventions, the presently described embodiments and / or examples, and any of the best modes currently understood for these inventions. DETAILED DESCRIPTION

[0033] To facilitate understanding of the present application, a more comprehensive description of the present application will be provided below with reference to the accompanying drawings. The accompanying drawings illustrate preferred embodiments of the present application. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the disclosure of the present application.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0035] The "ranges" disclosed in this application can be defined in the form of lower limits and upper limits. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of the particular range. Ranges defined in this way can be inclusive or exclusive of the end values, any end value can be included or excluded independently, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4, and 5 are also listed, the following ranges are all expected: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In this application, unless otherwise specified, the numerical range "a to b" is an abbreviation for any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to listing the parameter as, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, and so on. For example, when a parameter is expressed as an integer selected from "2-10," this is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0036] In this application, "a plurality of" or "a plurality of" refers to a number greater than or equal to 2 unless otherwise specified. For example, "one or more" means one or more than or equal to two.

[0037] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0038] References to "embodiments" herein mean that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment or implementation of the present application. The appearance of such phrases in various locations in the specification does not necessarily refer to the same embodiment, nor does it necessarily refer to independent or alternative embodiments that are mutually exclusive with other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments. References to "implementations" herein have a similar understanding.

[0039] It will be appreciated by those skilled in the art that, in the methods of various embodiments or examples, the order in which the steps are written does not imply a strict order of execution and does not constitute any limitation on the implementation process, and the detailed order of execution of each step should be determined by its function and possible inherent logic. Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0040] In this application, open technical features or technical solutions described with words such as "contain," "include," and "includes" do not exclude additional members beyond the listed members unless otherwise specified, and can be regarded as providing both closed features or solutions consisting of the listed members and open features or solutions that include additional members beyond the listed members. For example, if A includes a1, a2, and a3, it may or may not include other members unless otherwise specified. This can be regarded as providing both the feature or solution of "A consists of a1, a2, and a3" and the feature or solution of "A includes not only a1, a2, and a3, but also other members."

[0041] In this application, unless otherwise specified, A (such as B) means that B is a non-limiting example of A, and it can be understood that A is not limited to B.

[0042] One embodiment of the present application provides a pole piece, including a current collector and an active material layer arranged on at least one surface of the current collector; within each standard area, the mass of the current collector is a, the mass of the active material layer is b, and a and b satisfy: 0.02≤a / b≤0.3.

[0043] By rationally controlling the mass ratio of the current collector to the active material layer, the above-mentioned electrode can reduce the direct current resistance (DCR) of the battery on the basis of adopting a lighter current collector such as a composite current collector, thereby achieving a lightweight design while having good fast charging performance.

[0044] It can be understood that "1 standard area" refers to the area of ​​the standard circle of the pole piece obtained by punching in the current battery production process, specifically 1540.25 square meters (mm 2 ).

[0045] Specifically, the ratio of a / b includes but is not limited to 0.02, 0.025, 0.03, 0.04, 0.0486, 0.05, 0.08, 0.0942, 0.0971, 0.1, 0.12, 0.15, 0.17, 0.2, 0.2387, 0.2397, 0.25, 0.3 or a range between any two of the foregoing.

[0046] In some embodiments, the mass of the current collector per standard area is 16 mg to 40 mg. Specifically, the mass of the current collector includes, but is not limited to, 16 mg, 17 mg, 18 mg, 19 mg, 19.2 mg, 19.5 mg, 20 mg, 23 mg, 25 mg, 27 mg, 30 mg, 33.7 mg, 33.9 mg, 35 mg, 37 mg, 40 mg, or a range between any two of the foregoing.

[0047] In some embodiments, the mass of the active material layer per standard area is 130 mg to 660 mg. Specifically, the mass of the active material layer includes, but is not limited to, 130 mg, 135 mg, 141.4 mg, 145 mg, 150 mg, 155 mg, 160 mg, 200 mg, 250 mg, 300 mg, 350 mg, 357.6 mg, 400 mg, 550 mg, 556 mg, 600 mg, 630 mg, 630 mg, 640 mg, 650 mg, 660 mg, or a range between any two of the foregoing.

[0048] In some embodiments, the current collector includes a polymer base layer and a metal layer disposed on at least one surface of the polymer base layer, and the active material layer is disposed on the surface of the metal layer. Without limitation, the structure of the pole piece is shown in FIG1 , comprising a polymer base layer 100, metal layers 201 and 202 disposed on opposite sides of the polymer base layer 100, and active material layers 301 and 302 disposed on the surfaces of the metal layers 201 and 202, respectively.

[0049] In some embodiments, per standard area, the mass of the polymer material base layer is c, and the mass of the metal layer is d, where c and d satisfy the following relationship: 0.1≤c / d≤5. Specifically, the ratio of c / d includes, but is not limited to, 0.1, 0.15, 0.1764, 0.1782, 0.2, 0.2255, 0.25, 0.3, 0.4, 0.5, 0.7, 1, 1.2, 1.5, 1.7, 1.7835, 2, 2.5, 2.7654, 2.7903, 3, 3.5, 4, 4.5, 5, or any range between any two of the foregoing. Reasonable control of the mass ratio of the polymer material base layer to the metal layer can further reduce the internal resistance of the battery while reducing the weight of the electrode.

[0050] In some embodiments, the mass of the polymer material base layer is 3 mg to 20 mg per standard area. Specifically, the mass of the polymer material base layer includes but is not limited to: 3 mg, 3.5 mg, 4 mg, 4.5 mg, 4.9 mg, 5 mg, 5.5 mg, 6 mg, 6.2 mg, 6.5 mg, 7 mg, 7.5 mg, 8 mg, 10 mg, 13 mg, 15 mg, 17 mg, 17.3 mg, 18 mg, 19 mg, 20 mg or a range between any two of the foregoing. Without limitation, the polymer material base layer includes a polypropylene (PP) layer, a polyethylene terephthalate (PET) layer, a polybutylene terephthalate (PBT) layer, a polystyrene (PS) layer, a polyethylene (PE) layer or a composite layer formed by stacking any two or more of the foregoing layers.

[0051] In some embodiments, the mass of the metal layer per standard area is 4 mg to 30 mg. Specifically, the mass of the metal layer includes, but is not limited to, 4 mg, 4.5 mg, 5 mg, 5.5 mg, 6 mg, 6.2 mg, 6.5 mg, 7 mg, 9 mg, 9.7 mg, 10 mg, 10.5 mg, 11 mg, 13 mg, 15 mg, 17 mg, 20 mg, 23 mg, 25 mg, 27.5 mg, 30 mg, or a range between any two of the foregoing.

[0052] It can be understood that the quality of the current collector, the active material layer, the polymer material base layer, and the active material layer can be adjusted by adjusting their thicknesses.

[0053] Furthermore, the electrode sheet is a positive electrode sheet, and the active material layer is a positive electrode active material layer.

[0054] In some embodiments, the metal layer includes an aluminum layer, an aluminum alloy layer, a nickel layer, a nickel alloy layer, a titanium layer, a titanium alloy layer, a silver layer, a silver alloy layer, or a composite layer formed by stacking any two or more of the foregoing layers.

[0055] Furthermore, the electrode sheet is a negative electrode sheet, and the active material layer is a negative electrode active material layer.

[0056] In some embodiments, the metal layer includes a copper layer, a copper alloy layer, a nickel layer, a nickel alloy layer, a titanium layer, a titanium alloy layer, a silver layer, a silver alloy layer, or a composite layer formed by stacking any two or more of the foregoing layers.

[0057] Another embodiment of the present application provides a battery cell. The battery cell includes the above-mentioned pole piece.

[0058] In some embodiments, the battery cell includes a housing for accommodating an electrode assembly, and the electrode assembly includes the electrode sheet.

[0059] In some embodiments, the shell is square in shape and includes a shell and at least one end cover, the shell has an opening at only one end, and the end cover covers the opening; or both ends of the shell have openings, and the two end covers respectively cover the two openings.

[0060] In some embodiments, the shell is a soft package structure, and the shell includes an aluminum-plastic film.

[0061] In some embodiments, the housing is cylindrical in shape and includes a shell and at least one end cover, wherein the end cover covers an opening of the shell, and an outer diameter of the cylinder is greater than or equal to 30 millimeters (mm).

[0062] Another embodiment of the present application provides a battery comprising the above-mentioned battery cell.

[0063] Another embodiment of the present application provides an electrical device, which includes the aforementioned electrode piece, the aforementioned battery cell, or the aforementioned battery.

[0064] The battery and the electrical device of the present application will be described below with reference to the accompanying drawings as appropriate.

[0065] Typically, a battery cell consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During the battery's charge and discharge processes, active ions are inserted and removed between the positive and negative electrodes. The electrolyte conducts ions between the positive and negative electrodes. The separator, located between the positive and negative electrodes, primarily prevents short circuits between the positive and negative electrodes while allowing ions to pass through.

[0066] The positive electrode plate includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector, wherein the positive electrode active material layer includes a positive electrode active material. It is understood that the positive electrode plate can be a conventional positive electrode plate in the art or a positive electrode plate as described above.

[0067] As a non-limiting example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material layer is disposed on either or both of the two facing surfaces of the positive electrode current collector.

[0068] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector may be obtained by forming a metal material on a polymer material substrate. In the positive electrode current collector, non-limiting examples of the metal material may include one or more of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy. In the positive electrode current collector, non-limiting examples of the polymer material substrate may include one or more of substrates such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0069] In some embodiments, the positive electrode active material may be a positive electrode active material for a battery that is well known in the art. As a non-limiting example, the positive electrode active material may include one or more of the following materials: an olivine-structured lithium-containing phosphate, a lithium transition metal oxide, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides may include, but are not limited to, one or more of lithium cobalt oxide (such as LiCoO2), lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their modified compounds. Non-limiting examples of olivine-structured lithium-containing phosphates may include, but are not limited to, one or more of lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon. Non-limiting examples of lithium cobalt oxides may include LiCoO2; non-limiting examples of lithium nickel oxides may include LiNiO2; non-limiting examples of lithium manganese oxides may include LiMnO2, LiMn2O4, etc.; non-limiting examples of lithium nickel cobalt manganese oxides may include LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ) etc. Non-limiting examples of lithium nickel cobalt aluminum oxide may include LiNi 0.8 Co 0.15 Al 0.05 O2.

[0070] In some embodiments, the positive electrode active material layer may further optionally include a binder. As non-limiting examples, the binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0071] In some embodiments, the positive electrode active material layer may further include a conductive agent. As non-limiting examples, the conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0072] In some embodiments, the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder, and any other components, are dispersed in a solvent to form a positive electrode slurry; the positive electrode slurry is coated on at least one side of the positive electrode current collector, and after drying, cold pressing, and other processes, the positive electrode sheet can be obtained. The type of solvent can be selected from but is not limited to any of the aforementioned embodiments, such as N-methylpyrrolidone (NMP). The surface of the positive electrode current collector coated with the positive electrode slurry can be on a single surface of the positive electrode current collector or on both surfaces of the positive electrode current collector. The surface of the positive electrode current collector coated with the positive electrode slurry can be on a single surface of the positive electrode current collector or on both surfaces of the positive electrode current collector. The solid content of the positive electrode slurry can be 40 wt% to 80 wt%. The viscosity of the positive electrode slurry at room temperature can be adjusted to 5000 mPa·s (mPa·s) to 25000 mPa·s. When applying the positive electrode slurry, the coating unit area density based on dry weight (excluding solvent) can be 15 mg / cm2 (mg / cm 2 )~35mg / cm 2The compacted density of the positive electrode can be 3.0 g / cm3 (g / cm 3 )~3.6g / cm 3 , optional 3.3g / cm 3 ~3.5g / cm 3 .

[0073] The negative electrode plate includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode active material layer includes a negative electrode active material. It is understood that the negative electrode plate can be a conventional negative electrode plate in the art, or can be the negative electrode plate described above.

[0074] As a non-limiting example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material layer is disposed on either or both of the two facing surfaces of the negative electrode current collector.

[0075] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be obtained by forming a metal material on a polymer material substrate. In the negative electrode current collector, non-limiting examples of the metal material may include one or more of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy. In the negative electrode current collector, non-limiting examples of the polymer material substrate may include one or more of substrates such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE).

[0076] In some of these embodiments, the negative electrode active material may be a negative electrode active material for a battery that is well known in the art. As a non-limiting example, the negative electrode active material may include one or more of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. Silicon-based materials may include one or more of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may include one or more of elemental tin, tin oxides, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0077] In some embodiments, the negative electrode active material layer may further include a binder. The binder may include one or more of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0078] In some embodiments, the negative electrode active material layer may further include a conductive agent, which may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0079] In some embodiments, the negative electrode active material layer may optionally further include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0080] In some embodiments, the negative electrode sheet can be prepared in the following manner: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (a non-limiting example of the solvent is deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on at least one side of the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained. The surface of the negative electrode current collector coated with the negative electrode slurry can be a single surface of the negative electrode current collector or on both surfaces of the negative electrode current collector. The solid content of the negative electrode slurry can be 40wt% to 60wt%. The viscosity of the negative electrode slurry at room temperature can be adjusted to 2000mPa·s to 10000mPa·s. When coating the negative electrode slurry, the coating unit surface density on a dry weight basis (excluding the solvent) can be 75g / m 2 ~220g / m 2 The compaction density of the negative electrode can be 1.0g / cm 3 ~1.8g / cm 3 .

[0081] The electrolyte conducts ions between the positive and negative electrodes. This application does not specifically limit the type of electrolyte, and the electrolyte can be selected based on the needs. For example, the electrolyte can be liquid, gel, or solid.

[0082] In some embodiments, the electrolyte is an electrolyte solution comprising an electrolyte salt and a solvent.

[0083] In some embodiments, the electrolyte salt may include one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bisfluorosulfonyl imide (LiFSI), lithium bistrifluoromethanesulfonyl imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorophosphate (LiPO2F2), lithium difluorooxalatoborate (LiDFOB), lithium dioxalatoborate (LiBOB), lithium difluorobisoxalatophosphate (LiDFOP) and lithium tetrafluorooxalatophosphate (LiTFOP).

[0084] In some embodiments, the solvent may include ethylene carbonate (EC, ), propylene carbonate (PC, ), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate One or more of fluoroethylene carbonate (FEC), methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0085] In some embodiments, the electrolyte may optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, and additives that improve battery high or low temperature performance.

[0086] In some embodiments, the additives in the electrolyte may include, but are not limited to, one or more of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoromethylethylene carbonate (TFPC), and the like.

[0087] In some embodiments, the battery cell further includes a separator. This application has no particular limitation on the type of separator, and any known porous separator with good chemical and mechanical stability can be selected.

[0088] In some embodiments, the material of the separator may include one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer may be the same or different, without particular limitation.

[0089] In some embodiments, the isolation film has a thickness of 6 μm to 40 μm, and optionally 12 μm to 20 μm.

[0090] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be formed into an electrode assembly through a winding process or a lamination process.

[0091] In some embodiments, the battery cell may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0092] In some embodiments, the outer packaging of the battery cell may be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the outer packaging of the battery cell may be a soft shell, such as a pouch-type soft shell. The soft shell may be made of plastic. Non-limiting examples of the plastic include one or more of polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0093] A battery includes at least one battery cell. A battery may include one or more battery cells.

[0094] In this application, unless otherwise specified, a "battery cell" refers to a basic unit that can achieve the mutual conversion of chemical energy and electrical energy. Further, generally speaking, it includes at least a positive electrode plate, a negative electrode plate, and an electrolyte. During the battery's charge and discharge process, active ions are embedded in and out of the positive and negative electrode plates. The electrolyte plays the role of conducting active ions between the positive and negative electrode plates.

[0095] The present application has no particular limitation on the shape of the battery cell, which can be cylindrical, square, or any other shape. For example, FIG2 shows a battery cell 1 with a square structure as an example.

[0096] In some embodiments, referring to Figure 3, the outer packaging may include a shell 11 and a cover plate 13. The shell 11 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose a receiving cavity. The shell 11 has an opening connected to the receiving cavity, and the cover plate 13 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can be formed into an electrode assembly 12 through a winding process or a lamination process. The electrode assembly 12 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 12. The number of electrode assemblies 12 contained in the battery cell 1 can be one or more, and those skilled in the art can select according to actual needs.

[0097] The battery may be a battery module or a battery pack.

[0098] A battery module includes at least one battery cell. The number of battery cells contained in a battery module can be one or more, and those skilled in the art can select an appropriate number based on the application and capacity of the battery module.

[0099] In a battery module, multiple battery cells can be arranged in sequence along the length of the battery module. Of course, they can also be arranged in any other manner. Further, the multiple battery cells can be fixed by fasteners.

[0100] Optionally, the battery module may further include a housing having an accommodation space, wherein the plurality of battery cells are accommodated in the accommodation space.

[0101] In some embodiments, the battery modules may be assembled into a battery pack. The battery pack may contain one or more battery modules. Those skilled in the art may select an appropriate number based on the application and capacity of the battery pack.

[0102] A battery pack may include a battery box and multiple battery modules disposed within the box. The battery box comprises an upper case and a lower case. The upper case can be placed over the lower case to form an enclosed space for accommodating the battery modules. The multiple battery modules can be arranged in any manner within the battery box.

[0103] In addition, the present application also provides an electrical device, which includes the battery provided in the present application. The battery can serve as a power source for the electrical device or as an energy storage unit for the electrical device. The electrical device can include, but is not limited to, mobile devices, electric vehicles, electric trains, ships, satellites, energy storage systems, etc. Among them, mobile devices can be, for example, mobile phones, laptop computers, etc.; electric vehicles can be, for example, pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc., but are not limited to these.

[0104] As an electrical device, a battery can be selected according to its usage requirements.

[0105] FIG4 shows an example of an electric device 2. The electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the electric device's requirements for high power and high energy density, a battery pack or battery module may be used.

[0106] Another example device may be a mobile phone, a tablet computer, a laptop computer, etc. Such a device is usually required to be light and thin, and may use a battery as a power source.

[0107] In order to make the technical problems, technical solutions and beneficial effects solved by this application clearer, the application will be further described in detail below with reference to the embodiments and drawings. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present application and its applications. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0108] If no specific techniques or conditions are specified in the examples, the experiments were carried out according to the techniques or conditions described in the literature in the field or according to the product instructions. All reagents or instruments used without specifying the manufacturer are commercially available conventional products.

[0109] Example 1

[0110] This embodiment is a positive electrode sheet, as shown in FIG1 , comprising a PET layer 100 (8 μm thick), an Al layer 201 (1 μm thick) and an Al layer 202 (1 μm thick) disposed on opposite sides of the PET layer 100, and active material layers 301 and 302 disposed on the surfaces of the Al layer 201 and the Al layer 202, respectively. The active material layers 301 and 302 both comprise a positive electrode active material NCM in a weight ratio of 98:1:1. 9 / 0.5 / 0.5 , conductive carbon black SP and binder PVDF.

[0111] Among them, for each standard area of ​​the positive electrode sheet, the mass (a) of the current collector (PET layer + two Al layers) is 27 mg, the mass (b) of the two active material layers is 556 mg, a / b=0.0486; the mass (c) of the PET layer is 17.3 mg, the mass (d) of the two Al layers is 9.7 mg, c / d=1.7835.

[0112] In Comparative Example 1, pure Al foil with a thickness of 10 μm was used as the current collector of the positive electrode sheet.

[0113] The positive electrode sheets of Example 1 and Comparative Example 1 were respectively made into Battery 1 and Battery D1 according to conventional methods. The negative electrode sheet was pure copper foil, the isolation membrane was 12 μm thick polypropylene as the isolation membrane, the organic solvent of the electrolyte was a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC), the volume ratio of EC, EMC and DEC was 20:20:60, and the concentration of the lithium salt LiPF6 was 1 mol / L.

[0114] Example 2

[0115] This embodiment is a negative electrode sheet, as shown in Figure 1, including a PP layer 100 (thickness 4.5μm), a Cu layer 201 (thickness 1μm) and a Cu layer 202 (thickness 1μm) arranged on opposite sides of the PP layer 100, and an active material layer 301 and an active material layer 302 respectively arranged on the surfaces of the Cu layer 201 and the Cu layer 202. The active material layers 301 and 302 both include negative electrode active material graphite, thickener sodium carboxymethyl cellulose, binder styrene butadiene rubber, and conductive agent acetylene black in a weight ratio of 97:1:1:1.

[0116] Among them, for each standard area of ​​the negative electrode sheet, the mass (a) of the current collector (PP layer + two Cu layers) is 33.7 mg, the mass (b) of the two active material layers is 357.6 mg, a / b=0.0942; the mass (c) of the PP layer is 6.2 mg, the mass (d) of the two Cu layers is 27.5 mg, c / d=0.2255.

[0117] In Comparative Example 2, pure Cu foil with a thickness of 6.5 μm was used as the current collector of the negative electrode.

[0118] The negative electrode sheets of Example 2 and Comparative Example 2 were respectively made into Battery 2 and Battery D2 according to the traditional method. The positive electrode sheet was pure Al foil, the isolation membrane was 12 μm thick polypropylene as the isolation membrane, the organic solvent of the electrolyte was a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC), the volume ratio of EC, EMC and DEC was 20:20:60, and the concentration of lithium salt LiPF6 was 1 mol / L.

[0119] Test example:

[0120] The test method is as follows:

[0121] (1) DCR test method:

[0122] At 25°C, adjust the battery cell to 50% SOC and discharge it at 500A DC for 10 seconds. Measure the open circuit voltage before and after discharge, and calculate the discharge DC resistance (DCR) using Ohm's law. The steps are as follows:

[0123] 1) Let it stand for 5 minutes;

[0124] 2) 1 / 3C constant current charging to 4.25V and then constant voltage holding until the current drops to 0.05C;

[0125] 3) Let it stand for 30 minutes;

[0126] 4) 1C constant current discharge for 30 minutes (adjust to 50% SOC);

[0127] 5) Let stand for 60 minutes;

[0128] 6) 500A constant current discharge for 10s;

[0129] 7) Let it stand for 30 minutes.

[0130] The calculation formula is as follows:

[0131] DCR (unit: mΩ) = (open-circuit voltage in the last 1 second of step 5 - open-circuit voltage in the last 1 second of step 6) / average current in step 7 * 1000.

[0132] (2) Calculation method of pole piece weight reduction:

[0133] Example 1 pole piece weight reduction = Example 1 pole piece weight - Comparative Example 1 pole piece weight

[0134] Example 2 pole piece weight reduction = Example 2 pole piece weight - Comparative Example 2 pole piece weight

[0135] The test results are shown in Table 1 below:

[0136] Table 1

[0137] It can be seen that the electrode of the embodiment has a battery internal resistance that is equivalent to or lower than that of the comparative example, and is lighter in weight.

[0138] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0139] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A pole piece comprising a current collector and an active material layer disposed on at least one surface of the current collector; within each standard area, the mass of the current collector is a, the mass of the active material layer is b, and a and b satisfy: 0.02≤a / b≤0.

3.

2. The pole piece according to claim 1, wherein: The mass of the current collector in each standard area is 16 mg to 40 mg.

3. The pole piece according to claim 1 or 2, wherein: The mass of the active material layer per standard area is 130 mg to 660 mg.

4. The pole piece according to any one of claims 1 to 3, wherein: The current collector includes a polymer material base layer and a metal layer located on at least one surface of the polymer material base layer, and the active material layer is disposed on the surface of the metal layer.

5. The pole piece according to claim 4, wherein: In each standard area, the mass of the polymer material base layer is c, the mass of the metal layer is d, and c and d satisfy: 0.1≤c / d≤5.

6. The pole piece according to claim 4 or 5, wherein: In each standard area, the mass of the polymer material base layer is 3 mg to 20 mg.

7. The pole piece according to any one of claims 4 to 6, wherein: The mass of the metal layer in each standard area is 4 mg to 30 mg.

8. The pole piece according to any one of claims 4 to 7, wherein: The polymer material base layer includes a polypropylene layer, a polyethylene terephthalate layer, a polybutylene terephthalate layer, a polystyrene layer, a polyethylene layer, or a composite layer formed by stacking any two or more of the aforementioned layers.

9. The pole piece according to any one of claims 4 to 8, wherein: The metal layer includes an aluminum layer, an aluminum alloy layer, a nickel layer, a nickel alloy layer, a titanium layer, a titanium alloy layer, a silver layer, a silver alloy layer, or a composite layer formed by stacking any two or more of the foregoing layers; or the metal layer includes a copper layer, a copper alloy layer, a nickel layer, a nickel alloy layer, a titanium layer, a titanium alloy layer, a silver layer, a silver alloy layer, or a composite layer formed by stacking any two or more of the foregoing layers.

10. A battery cell comprising the electrode according to any one of claims 1 to 9.

11. The battery cell according to claim 10, wherein: The battery cell includes a shell, the shell is used to accommodate an electrode assembly, and the electrode assembly includes the electrode sheet.

12. The battery cell according to claim 11, wherein: The housing is square in shape, and comprises a shell and at least one end cover, wherein only one end of the shell has an opening, and the end cover covers the opening; or Both ends of the shell have openings, and the two end covers cover the two openings respectively.

13. The battery cell according to claim 11 or 12, wherein: The shell is a soft package structure and comprises an aluminum-plastic film.

14. The battery cell according to claim 11, wherein The outer shell is in the shape of a cylinder and comprises a shell and at least one end cover, wherein the end cover covers an opening of the shell, and an outer diameter of the cylinder is greater than or equal to 30 mm.

15. A battery comprising the battery cell according to any one of claims 10 to 14.

16. An electrical device comprising the electrode according to any one of claims 1 to 9, the battery cell according to any one of claims 10 to 14, or the battery according to claim 15.

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