Pole piece, battery monomer comprising pole piece, battery and electric device

Abstract

The utility model provides a pole piece, a battery monomer comprising the pole piece, a battery and an electric device. The pole piece comprises a current collector and an active material layer arranged on at least one surface of the current collector, and in each standard area, the mass of the current collector is a, the mass of the active material layer is b, and a and b meet the condition that a / b is more than or equal to 0.02 and less than or equal to 0.3. The battery with the composite current collector is small in internal resistance and light in weight.

Description

Technical Field

[0001] 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

[0002] The statements herein merely provide background information related to the present application and do not necessarily constitute prior art.

[0003] In recent years, lithium-ion batteries have been widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles and other fields, and their application range is becoming more and more extensive. As lithium-ion batteries have made great progress, the requirements for their performance are becoming more and more personalized. In addition to the traditional energy density, cycle performance and safety performance improvements, the demand for lightweight batteries is also increasing.

[0004] The composite current collector includes a polymer material base and a metal layer disposed on at least one surface of the polymer material base. Compared with the traditional pure metal current collector, the polymer material base is lighter, so the overall weight of the pole piece can be reduced. However, the introduction of the polymer material base also increases the battery DC resistance (DCR), making it difficult to match the fast charging requirements. Utility Model Content

[0005] 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 comprising the pole piece.

[0006] 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.

[0007] 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.

[0008] In some of the embodiments, the mass of the current collector is 16 mg to 40 mg per standard area.

[0009] In some embodiments, the mass of the active material layer per standard area is 130 mg to 660 mg.

[0010] 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.

[0011] In some embodiments, within 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. 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 and the weight of the pole piece.

[0012] In some of the embodiments, the mass of the polymer material base layer is 3 mg to 20 mg per standard area.

[0013] In some of the embodiments, the mass of the metal layer per standard area is 4 mg to 30 mg.

[0014] In some of the 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.

[0015] 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.

[0016] A second aspect of the present application provides a battery cell, comprising the pole piece described in the first aspect.

[0017] In some embodiments, the battery cell includes a housing for accommodating an electrode assembly, and the electrode assembly includes the electrode sheet.

[0018] In some embodiments, the outer shell 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 respectively cover the two openings.

[0019] In some embodiments, the shell is a soft package structure, and the shell includes an aluminum-plastic film.

[0020] 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.

[0021] A third aspect of the present application provides a battery, comprising the battery cell described in the second aspect.

[0022] A fourth aspect of the present application provides an electrical device, comprising the pole piece 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

[0023] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings used in the present application. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on the drawings without creative work.

[0024] Figure 1 A schematic diagram of a pole piece according to an embodiment of the present application.

[0025] Figure 2 It is a schematic diagram of a battery cell according to an embodiment of the present application.

[0026] Figure 3 for Figure 2 An exploded view of a battery according to an embodiment of the present application is shown.

[0027] Figure 4 A schematic diagram of an electrical device using a battery as a power source according to an embodiment of the present application.

[0028] Description of reference numerals:

[0029] 1. Battery; 11. Shell; 12. Electrode assembly; 13. Cover plate; 2. Electrical device.

[0030] In order to better describe and illustrate the embodiments and / or examples of the utility models disclosed herein, reference may be made to one or more drawings. The additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed utility models, the embodiments and / or examples currently described, and the best modes of these utility models currently understood. DETAILED DESCRIPTION

[0031] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present application are given in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which the present application belongs. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0033] The "range" disclosed in the present application can be defined in the form of a lower limit and an upper limit, and 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 a particular range. The range defined in this way can be inclusive or exclusive of the end values, and 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 a range of 60 to 120 and 80 to 110 is listed for a specific parameter, it is understood that the range of 60 to 110 and 80 to 120 is 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 can all be expected: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4 and 2 to 5. In the present application, unless otherwise specified, the numerical range "a to b" represents an abbreviation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to listing the parameter as, for example, integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For example, when a parameter is expressed as an integer selected from "2-10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9 and 10.

[0034] In the present application, "plurality", "multiple" and the like, unless otherwise specified, refer to a number greater than or equal to 2. For example, "one or more" means one or greater than or equal to two.

[0035] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0036] Reference to "embodiments" herein means 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 the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments. The "implementation methods" mentioned herein have a similar understanding.

[0037] Those skilled in the art will appreciate that, in the methods of each embodiment or example, the order in which each step is written does not mean 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 internal logic. If there is no special explanation, all steps of the present application can 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 also include step (c), indicating that step (c) can 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.

[0038] In this application, in the open technical features or technical solutions described by the words "contain", "include", "include", etc., if there is no other explanation, additional members other than the listed members are not excluded, and it can be regarded as providing both closed features or solutions consisting of the listed members and open features or solutions including additional members in addition to the listed members. For example, A includes a1, a2 and a3. If there is no other explanation, it may also include other members or may not include additional members. It 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".

[0039] 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.

[0040] An 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.

[0041] The above-mentioned pole piece can reduce the direct current resistance (DCR) of the battery by reasonably controlling the mass ratio of the current collector to the active material layer on the basis of using a lighter current collector such as a composite current collector, thereby achieving a lightweight design while having good fast charging performance.

[0042] 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 1540.25mm 2 .

[0043] 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.

[0044] In some embodiments, the mass of the current collector is 16 mg to 40 mg per standard area. 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.

[0045] In some embodiments, the mass of the active material layer is 130 mg to 660 mg per standard area. 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.

[0046] 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. Without limitation, the structure of the pole piece is as follows Figure 1 As shown, it includes a polymer material base layer 100, metal layers 201 and 202 arranged on opposite sides of the polymer material base layer 100, and active material layers 301 and 302 arranged on the surfaces of the metal layer 201 and 202 respectively.

[0047] In some embodiments, within 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. 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 a 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 pole piece.

[0048] 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.

[0049] In some embodiments, the mass of the metal layer is 4 mg to 30 mg per standard area. 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.

[0050] It can be understood that the mass of the current collector, the active material layer, the polymer material base layer, and the active material layer can be adjusted by adjusting the thickness thereof.

[0051] Furthermore, the pole piece is a positive pole piece, and the active material layer is a positive electrode active material layer.

[0052] 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.

[0053] Furthermore, the pole piece is a negative pole piece, and the active material layer is a negative electrode active material layer.

[0054] 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.

[0055] Another embodiment of the present application provides a battery cell. The battery cell includes the above-mentioned pole piece.

[0056] In some embodiments, the battery cell includes a housing for accommodating an electrode assembly, and the electrode assembly includes the electrode sheet.

[0057] In some embodiments, the outer shell 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 respectively cover the two openings.

[0058] In some embodiments, the shell is a soft package structure, and the shell includes an aluminum-plastic film.

[0059] 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.

[0060] Another embodiment of the present application provides a battery, which includes the above-mentioned battery cell.

[0061] Another embodiment of the present application provides an electrical device, which includes the above-mentioned pole piece, the above-mentioned battery cell or the above-mentioned battery.

[0062] The battery and the electrical device of the present application will be described below with reference to the accompanying drawings as appropriate.

[0063] Generally, a battery cell includes a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator. During the battery charging and discharging process, active ions are embedded and released back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte plays the role of conducting ions between the positive electrode sheet and the negative electrode sheet. The separator is set between the positive electrode sheet and the negative electrode sheet, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing ions to pass through.

[0064] The positive electrode sheet 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 can be understood that the positive electrode sheet can be a conventional positive electrode sheet in the art, or can be a positive electrode sheet as described above.

[0065] As a non-limiting example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode active material layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.

[0066] 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.

[0067] In some of the embodiments, the positive electrode active material may be a positive electrode active material for a battery known in the art. As a non-limiting example, the positive electrode active material may include one or more of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries 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, lithium cobalt oxides (such as LiCoO 2 ), one or more of 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 modified compounds thereof. Non-limiting examples of lithium phosphates containing an olivine structure 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 LiCoO 2 Non-limiting examples of lithium nickel oxides may include LiNiO 2 Non-limiting examples of lithium manganese oxides may include LiMnO 2 、LiMn 2 O 4 etc.; Non-limiting examples of lithium nickel cobalt manganese oxides may include LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 (Also referred to as NCM 333)、LiNi 0.5 Co 0.2 Mn 0.3 O 2 (Also referred to as NCM 523 )、LiNi 0.5 Co 0.25 Mn 0.25 O 2 (Also referred to as NCM 211 )、LiNi 0.6 Co 0.2 Mn 0.2 O 2 (Also referred to as NCM 622 )、LiNi 0.8 Co 0.1 Mn 0.1 O 2 (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 O 2 .

[0068] In some of these embodiments, the positive electrode active material layer may also optionally include a binder. As a non-limiting example, the binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0069] 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.

[0070] In some of the embodiments, the positive electrode sheet can be prepared in the following manner: 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 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 not limited to any one of the aforementioned embodiments, such as N-methylpyrrolidone (NMP). The surface of the positive electrode collector coated with the positive electrode slurry can be on a single surface of the positive electrode collector or on both surfaces of the positive electrode collector. The surface of the positive electrode collector coated with the positive electrode slurry can be on a single surface of the positive electrode collector or on both surfaces of the positive electrode collector. The solid content of the positive electrode slurry can be 40wt% to 80wt%. The viscosity of the positive electrode slurry at room temperature can be adjusted to 5000mPa·s to 25000mPa·s. When applying the positive electrode slurry, the coating unit surface density based on dry weight (excluding solvent) can be 15 mg / cm 2 ~35mg / cm 2 The compaction density of the positive electrode can be 3.0g / cm 3 ~3.6g / cm 3 , optional 3.3g / cm 3 ~3.5g / cm 3 .

[0071] 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 can be understood that the negative electrode plate can be a conventional negative electrode plate in the art, or can be a negative electrode plate as described above.

[0072] As a non-limiting example, the negative electrode current collector has two surfaces opposite to each other in its own thickness direction, and the negative electrode active material layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.

[0073] In some of the 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), etc.

[0074] In some of the embodiments, the negative electrode active material may adopt the negative electrode active material for batteries 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. The silicon-based material may include one or more of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may include one or more of elemental tin, tin oxide compounds, 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.

[0075] 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).

[0076] 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.

[0077] In some of the embodiments, the negative electrode active material layer may further include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0078] In some of the 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 surface of the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained. The surface of the negative electrode collector coated with the negative electrode slurry can be on a single surface of the negative electrode collector or on both surfaces of the negative electrode 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 sheet can be 1.0g / cm 3 ~1.8g / cm 3 .

[0079] The electrolyte has the function of conducting ions between the positive electrode and the negative electrode. The present application has no particular restrictions on the type of electrolyte, which can be selected according to needs. For example, the electrolyte can be liquid, gel or all-solid.

[0080] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.

[0081] In some embodiments, the electrolyte salt may include lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium perchlorate (LiClO 4 ) lithium hexafluoroarsenate (LiAsF 6 ), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorophosphate (LiPO 2 F 2 ), one or more of lithium difluorooxalatoborate (LiDFOB), lithium dioxalatoborate (LiBOB), lithium difluorobisoxalatophosphate (LiDFOP) and lithium tetrafluorooxalatophosphate (LiTFOP).

[0082] 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, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0083] In some embodiments, the electrolyte may further include additives, such as 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, additives that improve battery high or low temperature performance, etc.

[0084] 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.

[0085] In some embodiments, the battery cell further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical stability and mechanical stability can be selected.

[0086] In some embodiments, the material of the isolation membrane may include one or more of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The isolation membrane may be a single-layer film or a multi-layer composite film, without particular limitation. When the isolation membrane is a multi-layer composite film, the materials of each layer may be the same or different, without particular limitation.

[0087] In some embodiments, the isolation film has a thickness of 6 μm to 40 μm, and may be 12 μm to 20 μm.

[0088] In some of the embodiments, the positive electrode sheet, the negative electrode sheet and the separator can be formed into an electrode assembly by a winding process or a lamination process.

[0089] In some embodiments, the battery cell may include an outer packaging, which may be used to encapsulate the electrode assembly and the electrolyte.

[0090] In some embodiments, the outer packaging of the battery cell may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the battery cell may also be a soft package, such as a bag-type soft package. The material of the soft package may be plastic, and further, non-limiting examples of plastic may include one or more of polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0091] The battery includes at least one battery cell. The battery may include one or more battery cells.

[0092] In this application, unless otherwise specified, "battery cell" refers to a basic unit that can realize the mutual conversion of chemical energy and electrical energy, and further, generally speaking, at least includes a positive electrode sheet, a negative electrode sheet and an electrolyte. During the battery charging and discharging process, active ions are embedded and released back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte plays the role of conducting active ions between the positive electrode sheet and the negative electrode sheet.

[0093] The present application has no particular limitation on the shape of the battery cell, which may be cylindrical, square or any other shape. Figure 2 The battery cell 1 is a square structure as an example.

[0094] In some of these embodiments, reference Figure 3, the outer packaging may include a shell 11 and a cover plate 13. Among them, the shell 11 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate 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 form 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.

[0095] The battery may be a battery module or a battery pack.

[0096] The battery module includes at least one battery cell. The number of battery cells contained in the battery module can be one or more, and those skilled in the art can select a suitable number according to the application and capacity of the battery module.

[0097] In the battery module, the plurality of battery cells may be arranged in sequence along the length direction of the battery module. Of course, they may also be arranged in any other manner. Further, the plurality of battery cells may be fixed by fasteners.

[0098] Optionally, the battery module may further include a housing having an accommodation space, and the plurality of battery cells are accommodated in the accommodation space.

[0099] In some of the 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 a suitable number according to the application and capacity of the battery pack.

[0100] The battery pack may include a battery box and a plurality of battery modules disposed in the battery box. The battery box includes an upper box body and a lower box body, and the upper box body can be covered on the lower box body to form a closed space for accommodating the battery modules. The plurality of battery modules can be arranged in the battery box in any manner.

[0101] In addition, the present application also provides an electrical device, which includes the battery provided in the present application. The battery can be used as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device may include mobile devices, electric vehicles, electric trains, ships and satellites, energy storage systems, etc., but are not limited thereto. Among them, the mobile device may be, for example, a mobile phone, a laptop computer, etc.; the electric vehicle may be, for example, a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc., but are not limited thereto.

[0102] As an electrical device, a battery can be selected according to its usage requirements.

[0103] Figure 4 The power consumption device 2 is taken as an example. The power consumption device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the power consumption device's requirements for high power and high energy density of the battery, a battery pack or a battery module can be used.

[0104] As another example, the device may be a mobile phone, a tablet computer, a notebook computer, etc. The device is usually required to be light and thin, and a battery may be used as a power source.

[0105] In order to make the technical problems, technical solutions and beneficial effects solved by the present application clearer, the present application will be further described in detail below in conjunction with the embodiments and drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present application and its applications. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0106] If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the field or the product instructions are used. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0107] Example 1

[0108] This embodiment is a positive electrode sheet, such as Figure 1 As shown, it includes a PET layer 100 (with a thickness of 8 μm), an Al layer 201 (with a thickness of 1 μm) and an Al layer 202 (with a thickness of 1 μm) disposed on opposite sides of the PET layer 100, and an active material layer 301 and an active material layer 302 disposed on the surfaces of the Al layer 201 and the Al layer 202, respectively. The active material layers 301 and 302 both include a positive electrode active material NCM with a weight ratio of 98:1:1. 9 / 0.5 / 0.5 , conductive carbon black SP and binder PVDF.

[0109] Among them, for each standard area of ​​the positive electrode sheet, the mass of the current collector (PET layer + two Al layers) (a) is 27 mg, the mass of the two active material layers (b) is 556 mg, a / b=0.0486; the mass of the PET layer (c) is 17.3 mg, the mass of the two Al layers (d) is 9.7 mg, c / d=1.7835.

[0110] In Comparative Example 1, pure Al foil with a thickness of 10 μm was used as the current collector of the positive electrode sheet.

[0111] The positive electrode plates of Example 1 and Comparative Example 1 were respectively made into Battery 1 and Battery D1 according to conventional methods. The negative electrode plates were 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.

[0112] Example 2

[0113] This embodiment is a negative electrode sheet, such as Figure 1 As shown, it includes a PP layer 100 (with a thickness of 4.5 μm), a Cu layer 201 (with a thickness of 1 μm) and a Cu layer 202 (with a thickness of 1 μm) arranged on the opposite side surfaces 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, wherein the active material layers 301 and 302 both include negative electrode active material graphite, thickener sodium carboxymethyl cellulose, adhesive styrene butadiene rubber and conductive agent acetylene black in a weight ratio of 97:1:1:1.

[0114] Among them, for each standard area of ​​the negative electrode sheet, the mass of the current collector (PP layer + two Cu layers) (a) is 33.7 mg, the mass of the two active material layers (b) is 357.6 mg, a / b=0.0942; the mass of the PP layer (c) is 6.2 mg, the mass of the two Cu layers (d) is 27.5 mg, c / d=0.2255.

[0115] In Comparative Example 2, pure Cu foil with a thickness of 6.5 μm was used as the current collector of the negative electrode.

[0116] The negative electrode plates of Example 2 and Comparative Example 2 were respectively made into Battery 2 and Battery D2 according to the conventional method. The positive electrode plate 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 the lithium salt LiPF6 was 1 mol / L.

[0117] Test example:

[0118] The test method is as follows:

[0119] (1) DCR test method:

[0120] At 25°C, adjust the battery cell to 50% SOC and discharge it at 500A DC for 10s. 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:

[0121] 1) Let stand for 5 minutes;

[0122] 2) 1 / 3C constant current charging to 4.25V and then constant voltage maintained until the current drops to 0.05C;

[0123] 3) Let stand for 30 minutes;

[0124] 4) 1C constant current discharge for 30 minutes (adjust to 50% SOC);

[0125] 5) Let stand for 60 minutes;

[0126] 6) 500A constant current discharge for 10s;

[0127] 7) Let stand for 30 minutes.

[0128] The calculation formula is as follows:

[0129] DCR (unit: mΩ) = (open circuit voltage in the last 1s of step 5 – open circuit voltage in the last 1s of step 6) / average current in step 7 * 1000.

[0130] (2) Calculation method of pole piece weight reduction:

[0131] Example 1 pole piece weight reduction = Example 1 pole piece weight - Comparative Example 1 pole piece weight

[0132] Example 2 pole piece weight reduction = Example 2 pole piece weight - Comparative Example 2 pole piece weight

[0133] The test results are shown in Table 1 below:

[0134] Table 1

[0135] DCR / mΩ Pole weight reduction Example 1 0.499 16.0mg Comparative Example 1 0.502 - Example 2 0.561 55.5mg Comparative Example 2 0.559 -

[0136] It can be seen that the pole piece 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.

[0137] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described 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.

[0138] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the utility model patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A pole piece, characterized in that: It comprises 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.

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

3. The pole piece according to claim 2, characterized in that: 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, characterized in that: 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, characterized in that: 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 5, characterized in that: In each standard area, the mass of the polymer material base layer is 3 mg to 20 mg.

7. The pole piece according to claim 5, characterized in that: The mass of the metal layer is 4 mg to 30 mg per standard area.

8. The pole piece according to claim 4, characterized in that: 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 aforementioned layers.

9. The pole piece according to claim 4, characterized in that: 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, characterized in that: A pole piece comprising any one of claims 1 to 9.

11. The battery cell according to claim 10, characterized in that: The battery cell comprises a shell, the shell is used to accommodate an electrode assembly, and the electrode assembly comprises the electrode sheet.

12. The battery cell according to claim 11, characterized in that: The outer shell is in a square 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, characterized in that: The shell is a soft package structure, and the shell comprises an aluminum-plastic film.

14. The battery cell according to claim 11, characterized in that: 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, characterized in that: A battery cell comprising the battery cell according to any one of claims 10 to 14.

16. An electrical device, characterized in that: It comprises the pole piece 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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