Battery cell, battery, and electric device

Abstract

A battery cell, a battery, and an electric device. The battery cell comprises a positive electrode sheet and a negative electrode sheet. The positive electrode sheet comprises a positive electrode active material, wherein the positive electrode active material at least comprises two types of positive electrode active materials; and the positive electrode active material at least comprises a ternary material, and the mass ratio of the ternary material is A on the basis of the total mass of the positive electrode active material. The negative electrode sheet comprises a negative electrode active material, wherein the negative electrode active material comprises a first negative electrode active material, and the capacity of the first negative electrode active material is greater than 375 mAh / g; and the mass ratio of the first negative electrode active material is B on the basis of the total mass of the negative electrode active material. The range of A:B is (10-200):1. By means of this arrangement, the dynamics of the positive electrode side can be effectively improved, and the deterioration of the dynamics of the negative electrode side can be alleviated, thereby improving the internal resistance of the battery cell.

Description

Battery cell, battery and electric device

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese Patent Application No. 202411095274.3, filed on August 9, 2024, entitled “Battery cell, battery and electric device”, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present application relates to the field of new energy technology, in particular to a battery cell, a battery and an electric device. BACKGROUND

[0004] With the development of modern science and technology, lithium ion batteries are considered to be the first choice of green and environmentally friendly batteries due to their high energy density, long cycle life, good environmental protection and other advantages. Lithium ion batteries can be widely used in energy storage power supply systems such as hydraulic, thermal, wind and solar power stations, and in many fields such as electric vehicles, electric tools, military equipment and aerospace.

[0005] In order to improve the capacity of the negative electrode in the lithium ion battery, a high-capacity negative electrode active material is usually mixed in the negative electrode active material, but this can cause other performance of the battery to deteriorate, such as poor kinetics, deteriorated internal resistance, etc. The above statements are only used to provide background technical information related to the present application, and do not necessarily constitute the prior art. SUMMARY

[0006] The technical problem solved by the present application is to provide a battery cell, a battery and an electric device, which can improve the internal resistance of the battery.

[0007] To solve the above technical problem, one technical solution adopted by the present application is to provide a battery cell, the battery cell comprising a positive electrode sheet and a negative electrode sheet, the positive electrode sheet comprising a positive electrode active layer, the positive electrode active layer comprising a positive electrode active material, the positive electrode active material comprising at least a ternary material, the mass fraction of the ternary material being A based on the total mass of the positive electrode active material in the positive electrode active layer; the negative electrode sheet comprising a negative electrode active layer, the negative electrode active layer comprising a first negative electrode active material, the capacity of the first negative electrode active material being greater than 375 mAh / g, the mass fraction of the first negative electrode active material being B based on the total mass of the negative electrode active material in the negative electrode active layer; wherein the range of A:B is (10-200):1. Through the above setting, the kinetics of the positive electrode side and the negative electrode side can be balanced, and the internal resistance of the battery cell can be improved.

[0008] In an embodiment, the range of A:B is (32.5-160):1. Through the above setting, the cooperation effect of the positive electrode active material and the negative electrode active material can be further enhanced, and the internal resistance of the battery cell can be improved.

[0009] In an embodiment, B ranges from 0.1% to 5%; and / or A ranges from 50% to 95%. By the above setting, the kinetic performance of the positive electrode tab is improved, and the problem of poor kinetic performance caused by high-capacity negative electrode active material is alleviated; the internal resistance of the battery cell is improved.

[0010] In an embodiment, B ranges from 0.5% to 2%; and / or A ranges from 65% to 80%. By the above setting, the kinetic performance of the positive electrode tab is improved, and the problem of poor kinetic performance caused by high-capacity negative electrode active material is alleviated; the internal resistance of the battery cell is improved.

[0011] In an embodiment, the positive electrode active material of the positive electrode active layer at least includes nickel element and cobalt element, wherein the total amount of the nickel element and the cobalt element accounts for 23%-35% of the total amount of metal elements in the positive electrode active material of the positive electrode active layer. By this setting, the internal resistance of the battery cell can be improved.

[0012] In an embodiment, the positive electrode active layer includes a first ternary material, the first ternary material at least includes nickel element, wherein the mass fraction of the nickel element in the total amount of metal elements is ≥0.7; and / or the positive electrode active layer includes a second ternary material, the second ternary material at least includes nickel element, wherein the mass fraction of the nickel element in the total amount of metal elements is 0.3-0.7. By this setting, the kinetic performance of the positive electrode tab can be improved, thereby effectively alleviating the negative kinetic deterioration and improving the internal resistance of the battery cell.

[0013] In an embodiment, the positive electrode active layer includes a third ternary material, the third ternary material at least includes cobalt element, wherein the mass fraction of the cobalt element in the total amount of metal elements is 5%-30%. Appropriately increasing the proportion of cobalt element can improve the kinetic performance of the positive electrode tab, thereby effectively alleviating the negative kinetic deterioration and improving the internal resistance of the battery cell.

[0014] In an embodiment, the positive electrode active layer includes a first polyanion material, the first polyanion material includes manganese element, wherein the mass fraction of the manganese element in the total amount of metal elements is 0.05-0.75. By limiting the content of Mn in the polyanion material, the conductivity of the positive electrode active layer can be effectively improved, and the internal resistance of the battery cell is improved.

[0015] In an embodiment, the mass fraction of the manganese element in the total amount of metal elements in the first polyanion material is 0.15-0.65. By limiting the content of Mn in the polyanion material, the conductivity of the positive electrode active layer can be effectively improved, and the internal resistance of the battery cell is improved.

[0016] In an embodiment, the first negative active material comprises a silicon-based negative active material. The silicon-based negative active material has a higher capacity than the carbon-based negative active material, and thus the above arrangement can significantly increase the capacity of the negative electrode sheet.

[0017] In an embodiment, the negative active layer further comprises a binder, and the mass percentage of the binder in the total mass of the negative active layer is C; wherein the range of C:B is (0.17-2):1. The content of the binder and the first negative active material on the negative electrode sheet is matched, which is beneficial to improve the electrical contact of the negative electrode sheet, maintain the integrity of the conductive network in the negative electrode sheet, and improve the internal resistance of the battery cell.

[0018] In an embodiment, the range of C is 1%-3%. Through the above arrangement, the matching degree of the content of the binder and the content of the first negative active material can be further improved, and the conductivity can be improved and the internal resistance of the battery cell can be reduced.

[0019] In an embodiment, the positive active layer comprises a compound of Li 1+x Mn 1-y A y P 1-z E z O4, wherein x is any value in the range of -0.100-0.100, y is any value in the range of 0.001-1.000, z is any value in the range of 0.001-0.100, A is selected from one or more elements of Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb and Ge, and E is selected from one or more elements of B, Si, N, S, F, Cl and Br. Through this arrangement, the structural stability of the lithium manganese iron phosphate positive active material can be improved, the dissolution of manganese can be greatly reduced and the oxygen activity on the particle surface can be reduced; the lithium ion migration is promoted, and the rate performance of the battery cell is improved.

[0020] In an embodiment, A is selected from one or more elements of Fe, Ti, V, Ni, Co and Mg; and / or E is selected from one element of B, Si, N and S. Through this arrangement, the structural stability of the positive active material and the rate performance of the battery cell can be further improved.

[0021] In an embodiment, the positive active material has a core-shell structure, and the coating shell layer of the core-shell structure comprises one or more layers of pyrophosphate, phosphate and carbon, and the core layer of the core-shell structure comprises the active material Li 1+x Mn 1-y A y P 1-z E z O4. Through this arrangement, the Li 1+x Mn 1-yA y P 1-z E z O4 material, reducing its dissolution in the electrolyte or corrosion of the electrolyte, which is conducive to improving the stability of the battery monomer and prolonging the cycle life of the battery monomer.

[0022] To solve the above technical problems, another technical solution adopted by the present application is to provide a battery, the battery comprising the battery monomer of any one of the above, the battery at least having the same advantages as the battery monomer.

[0023] To solve the above technical problems, another technical solution adopted by the present application is to provide a battery, the battery comprising the battery monomer of any one of the above, the battery at least having the same advantages as the battery monomer.

[0024] The above description is only a summary of the technical solutions of the present application, in order to enable the technical means of the present application to be more clearly understood, and to be implemented in accordance with the content of the description, and in order to enable the above and other purposes, features and advantages of the present application to be more apparent and easy to understand, the following specific embodiments of the present application are described. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0026] Fig. 1 is an exploded structural schematic diagram of a battery according to one or more embodiments;

[0027] Fig. 2 is an exploded structural schematic diagram of a battery monomer according to one or more embodiments;

[0028] Fig. 3 is a structural schematic diagram of a vehicle according to one or more embodiments.

[0029] In the drawings: 1000, vehicle; 300, motor; 200, controller; 100, battery; 10, box body; 11, first part; 12, second part; 20, battery monomer; 21, end cover; 21a, electrode terminal; 22, shell; 23, electrode assembly. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and effects of the present application more clear and explicit, the following will describe the embodiments of the technical solutions of the present application in detail in conjunction with the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, therefore only serve as examples, and cannot limit the protection scope of the present application.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application; the use of the terms "including," "comprising," or "having" and variations thereof herein is intended to be broad and encompass the terms "consisting of" and "consisting essentially of" and variations thereof, unless otherwise noted.

[0032] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the term "a plurality of" refers to two or more (including two), and similarly, "a plurality of groups" refers to two or more groups (including two groups), and "a plurality of pieces" refers to two or more pieces (including two pieces), unless otherwise explicitly and specifically limited.

[0033] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase that the phrase in the specification do not all necessarily refer to the same embodiment, nor are they necessarily mutually exclusive or alternative embodiments to one another. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0034] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " in this paper generally represents that the front and rear associated objects are a "or" relationship.

[0035] Quantities, ratios, and other numerical values are presented herein in a range format. It is to be understood that such range format is used merely for the convenience of the reader and is not intended to limit the actual scope of such quantities, ratios, and other numerical values. It is to be further understood that such a range format is used merely for the convenience of the reader and is not intended to limit the actual scope of such quantities, ratios, and other numerical values, which will be encompassed by the description below.

[0036] If not specified, all steps of the present application can be carried out in sequence, randomly, or in parallel, preferably in sequence. For example, the method comprises steps (a) and (b), indicating that the method can comprise steps (a) and (b) in sequence, steps (b) and (a) in sequence, or steps (a) and (b) in parallel. For example, the method can also comprise step (c), indicating that step (c) can be added to the method in any order. For example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0037] Lithium-ion batteries, as a new type of green secondary battery, are widely used in electric vehicles, energy storage systems and renewable energy fields. With the new development of lithium-ion batteries in China, lithium-ion batteries will achieve improvement in many aspects. From the technical aspect, in the improvement process, "high efficiency", "high long life" and "low cost" will be the core scheme and pursuit target of the development of power battery technology.

[0038] The present application provides a battery, please refer to Figure 1, Figure 1 is an exploded structural schematic diagram of a battery according to one or more embodiments. The battery 100 comprises a box 10 and a battery cell 20, the battery cell 20 is contained in the box 10. Among them, the box 10 is used to provide a containing space for the battery cell 20, the box 10 can adopt a variety of structures. In some embodiments, the box 10 can comprise a first part 11 and a second part 12, the first part 11 and the second part 12 are mutually covered, the first part 11 and the second part 12 jointly define a containing space for containing the battery cell 20. The second part 12 can be a hollow structure with one end open, the first part 11 can be a plate structure, the first part 11 covers the open side of the second part 12, so that the first part 11 and the second part 12 jointly define a containing space; the first part 11 and the second part 12 can also be hollow structures with one side open, the open side of the first part 11 covers the open side of the second part 12. Of course, the box 10 formed by the first part 11 and the second part 12 can be a variety of shapes, such as cylinder, cuboid, etc.

[0039] In the battery 100, the battery cells 20 can be multiple, and the multiple battery cells 20 can be connected in series, in parallel, or in a mixed manner. The mixed manner means that the multiple battery cells 20 are connected in series and in parallel. The multiple battery cells 20 can be directly connected in series, in parallel, or in a mixed manner, and the whole of the multiple battery cells 20 is accommodated in the case 10. Of course, the battery 100 can also be in a form that the multiple battery cells 20 are connected in series, in parallel, or in a mixed manner to form a battery module, and the multiple battery modules are connected in series, in parallel, or in a mixed manner to form a whole, and the whole is accommodated in the case 10. The battery 100 can also include other structures. For example, the battery 100 can also include a current collecting member for electrically connecting the multiple battery cells 20.

[0040] Each of the battery cells 20 can be a secondary battery or a primary battery, and can also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 20 can be in a shape of a cylinder, a flat body, a cuboid, or other shapes.

[0041] The present application also provides a battery cell. Please refer to FIG. 2, which is an exploded structural schematic diagram of a battery cell according to one or more embodiments. The battery cell 20 refers to the smallest unit that constitutes a battery. As shown in FIG. 2, the battery cell 20 includes an end cover 21, a shell 22, an electrode assembly 23, and other functional components.

[0042] The end cover 21 refers to a component that covers the opening of the shell 22 to isolate the internal environment of the battery cell 20 from the external environment. Without limitation, the shape of the end cover 21 can be adapted to the shape of the shell 22 to fit the shell 22. Optionally, the end cover 21 can be made of a material with certain hardness and strength (such as aluminum alloy), so that the end cover 21 is not easy to deform when subjected to extrusion and collision, so that the battery cell 20 can have higher structural strength, and the safety performance can also be improved. The end cover 21 can be provided with functional components such as an electrode terminal 21a. The electrode terminal 21a can be used to electrically connect with the electrode assembly 23 for outputting or inputting the electric energy of the battery cell 20. In some embodiments, the end cover 21 can also be provided with a pressure relief mechanism for relieving the internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold value. The material of the end cover 21 can also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application do not make special limitations thereon. In some embodiments, an insulating piece can also be provided on the inner side of the end cover 21, which can be used to isolate the electrical connection components in the shell 22 from the end cover 21 to reduce the risk of short circuit. Exemplarily, the insulating piece can be plastic, rubber, etc.

[0043] The shell 22 is a component used in cooperation with the end cover 21 to form an internal environment of the battery cell 20, and the formed internal environment can be used to accommodate the electrode assembly 23, electrolyte, and other components. The shell 22 and the end cover 21 can be independent components, and an opening can be provided on the shell 22, and the end cover 21 is used to cover the opening to form the internal environment of the battery cell 20. Without limitation, the end cover 21 and the shell 22 can also be integrated, specifically, the end cover 21 and the shell 22 can form a common connecting surface before other components enter the shell, and when it is necessary to seal the internal environment of the shell 22, the end cover 21 is used to cover the shell 22. The shell 22 can be of various shapes and sizes, such as a cuboid, a cylinder, a hexagonal prism, etc. Specifically, the shape of the shell 22 can be determined according to the specific shape and size of the electrode assembly 23. The material of the shell 22 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application do not make special limitations thereto.

[0044] The electrode assembly 23 is a component in which electrochemical reactions occur in the battery cell 100. One or more electrode assemblies 23 can be contained in the shell 22. The electrode assembly 23 is mainly formed by winding or stacking a positive electrode sheet and a negative electrode sheet, and a separator is usually provided between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet and the negative electrode sheet have a portion with active material constituting a main body of the electrode assembly, and a portion without active material of the positive electrode sheet and the negative electrode sheet respectively constituting a tab 23a. The positive electrode tab and the negative electrode tab can be located together at one end of the main body or respectively at both ends of the main body. In the charging and discharging process of the battery, the positive active material and the negative active material react with the electrolyte, and the tab 23a connects the electrode terminal to form a current loop.

[0045] In some embodiments, the positive electrode sheet includes a current collector and a positive active layer disposed on the current collector.

[0046] The positive active layer includes a positive active material, which can include at least one of a lithium-containing phosphate with an olivine structure, a lithium transition metal oxide, and a modified compound of each of them. However, the present application is not limited to these materials, and other conventional materials that can be used as positive active materials for batteries can also be used. These positive active materials can be used alone or in combination with two or more. Among them, examples of lithium transition metal oxides can include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 ), LiNi 0.5Co 0.2 Mn 0.3 O2(also can be referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2(also can be referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2(also can be referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2(also can be referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2), and modified compounds thereof. Examples of lithium-containing phosphates of olivine structure can include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4(also can be referred to as LFP)), a composite of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite of lithium manganese phosphate and carbon, lithium manganese iron phosphate, a composite of lithium manganese iron phosphate and carbon.

[0047] In an embodiment, the active layer of the cathode material further includes a conductive agent and a binder.

[0048] The conductive agent imparts electrical conductivity to the electrode. The cathode conductive material can include any electrically conductive material so long as it does not cause chemical changes. Non-limiting examples of cathode conductive materials include carbon-based materials (e.g., natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fibers, etc.), metal-based materials (e.g., metal powders, metal fibers, etc., including, for example, copper, nickel, aluminum, silver, etc.), conductive polymers (e.g., polyphenylene derivatives), and mixtures thereof. Optionally, the conductive agent includes one or more of conductive carbon black, conductive graphite, carbon fibers, carbon nanotubes, graphene, ketjen black, and acetylene black.

[0049] The binder improves the adhesion stability of the active layer and reduces the probability of powder falling. The binder can be one or more of styrene butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB). Optionally, the binder includes one or more of polyvinylidene fluoride, polytetrafluoroethylene, acrylate, polyurethane.

[0050] In an embodiment, the positive active layer further comprises other optional additives, which can be thickening and dispersing agents (such as sodium carboxymethyl cellulose CMC-Na), PTC thermistor materials.

[0051] In some embodiments, the negative electrode tab comprises a current collector and a negative active layer disposed on the current collector.

[0052] The negative active layer comprises a negative active material, which includes but is not limited to carbon-based negative materials, silicon-based negative materials, tin-based negative materials, lithium titanate negative materials, metal lithium negative materials, etc.; specifically includes but is not limited to graphite materials, silicon-carbon materials, graphite-silicon monoxide materials, nano-silicon materials, silicon monoxide materials, and tin-based materials; more specifically includes natural graphite, artificial graphite, mesophase carbon microbeads (MCMB for short), hard carbon, soft carbon, silicon, silicon-carbon composites, Li-Sn alloys, Li-Sn-O alloys, Sn, SnO, SnO2, spinel-structured Li4Ti5O12, and Li-Al alloys. 12

[0053] In some embodiments, the negative active layer can further comprise a binder, a conductive agent, and other optional additives. As an example, the conductive agent can be one or more of super conductive carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, Super P (SP), graphene, and carbon nanofibers. As an example, the binder can be one or more of styrene-butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB). As an example, the other optional additives can be thickening and dispersing agents (such as sodium carboxymethyl cellulose CMC-Na), PTC thermistor materials.

[0054] In some embodiments, the material of the separator film can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator film can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator film is a multi-layer composite film, the materials of the respective layers can be the same or different, without particular limitation.

[0055] In an embodiment, the electrolyte comprises one or more of carbonate solvents and ether solvents.

[0056] ​The carbonate is typically a small molecule cyclic or chain carbonate; including but not limited to one or more of ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, methyl propyl carbonate, dipropyl carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, one or more of fluoro-carbonate esters; can also be at least one ester solvent of gamma-butyrolactone, dimethyl sulfite, ethyl acetate, methyl acetate, methyl butyrate, ethyl butyrate, methyl propionate, ethyl propionate, propyl acetate, fluoro-carboxylate esters.

[0057] The ether solvent includes but is not limited to one or more of dimethyl ether, diethyl ether, tetrahydrofuran, methyl tetrahydrofuran, oxirane, 1,3-dioxolane, fluoro-ether, DME (ethylene glycol dimethyl ether), DEE (ethylene glycol diethyl ether), DEGDME (diethylene glycol dimethyl ether), TRGDME (triethylene glycol dimethyl ether), TEGDME (tetraethylene glycol dimethyl ether), dipropyl ether, and dibutyl ether.

[0058] In other embodiments, the electrolyte can also include any one or mixture of several of an amine solvent, a sulfone solvent, and a nitrile solvent. The amine solvent includes at least one of N-methylacetamide, N-methylformamide, dimethylformamide, diethylformamide. The sulfone solvent includes at least one of dimethyl sulfoxide, sulfolane, diphenyl sulfoxide, chlorosulfoxide, dipropyl sulfone. The nitrile solvent includes at least one of acetonitrile, butanedinitrile, hexanedinitrile, pentanedinitrile. The electrolyte is preferably a high-voltage electrolyte, which has reduced acidity at high voltage, can facilitate the transport of active ions, significantly reduces the side reactions on the electrode surface, and improves the stability of the battery.

[0059] In some embodiments, the electrolyte further includes an electrolyte salt, which can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonylimide, lithium bistrifluoromethylsulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorobisoxalate borate, lithium bisoxalate borate, lithium difluorobisoxalate phosphate, and lithium tetrafluorobisoxalate phosphate.

[0060] In some embodiments, the electrolyte can optionally further include an additive. For example, the additive can include a negative electrode film-forming additive, a positive electrode film-forming additive, and can also include an additive that can improve certain performance of the battery, such as an additive that improves the overcharge performance of the battery, an additive that improves the high-temperature or low-temperature performance of the battery, etc.

[0061] In the design of the negative active layer, in order to improve the capacity of the battery monomer, a material with relatively high capacity is selected, such as a silicon-based material, but the kinetics of silicon itself is poor, and if the silicon content is increased, the internal resistance of the battery monomer will deteriorate. Specifically, the silicon electrode material will pulverize and peel off from the current collector during the charging and discharging process, causing the active material to lose electrical contact between the active material and the active material, and the active material and the current collector, while continuously forming a new solid electrolyte layer, leading to the deterioration of the battery internal resistance and the reduction of the kinetics.

[0062] Based on the above technical problems, the present application provides a battery monomer, which comprises a positive electrode sheet and a negative electrode sheet. The positive electrode sheet comprises a positive active layer, and the positive active layer comprises a positive active material, wherein the positive active material at least comprises a ternary material, and the mass fraction of the ternary material is A based on the total mass of the positive active material in the positive active layer; the negative electrode sheet comprises a negative active layer, and the negative active layer comprises a first negative active material, wherein the capacity of the first negative active material is greater than 375 mAh / g, and the mass fraction of the first negative active material is B based on the total mass of the negative active material in the negative active layer; and the ratio of A to B is in the range of (10-200):1.

[0063] The negative active layer at least selects a high-capacity active material, and specifically selects an active material with a capacity of greater than 375 mAh / g, such as a silicon particle material with a capacity of 4200 mAh / g. The high-capacity silicon-based negative electrode material can improve the capacity of the negative active layer, but the kinetics of silicon itself is poor, and the increase of the silicon content in the negative electrode will easily cause the deterioration of the internal resistance of the battery monomer. In other embodiments, the negative active material comprises one or more of a silicon particle material, a silicon-oxygen material, a silicon-carbon material, and a lithium metal material. That is, the negative active material with a capacity of greater than 375 mAh / g comprises one or more of a silicon particle material with a capacity of 4200 mAh / g, a silicon-oxygen material with a capacity of 2600 mAh / g, a silicon-carbon material with a capacity of 1800 mAh / g, and a lithium metal material with a capacity of 3860 mAh / g. It can also be one or more of a carbon-based negative electrode, a sulfur-containing negative electrode, a metal negative electrode, an alloy negative electrode, and an oxide negative electrode.

[0064] Based on this, in the present embodiment, a ternary material is added to the positive active layer. The kinetics of the ternary material is good, and the use of the ternary material as the positive active material, in combination with the high-capacity negative electrode material, can improve the positive kinetics, alleviate the deterioration of the negative kinetics, and improve the internal resistance of the battery monomer.

[0065] Further, the range of A:B is (10-200):1, which can be 10:1, 15:1, 50:1, 100:1, 120:1, 200:1, or a range formed by any two of the above values, such as (10-15):1, (15-20):1, (50-100):1, (120-200):1, and the like. Through the above setting, the ratio of the ternary material and the first negative active material is optimized, the capacity of the battery monomer is improved, the kinetic performance of the battery monomer is improved, the matching of the positive active material and the negative active material is realized, and the specific embodiment is that the more the high-capacity first negative active material in the negative active material, the content of the high-kinetic-performance ternary material in the positive active material can be correspondingly increased.

[0066] In an embodiment, the range of A:B is (32.5-160):1. For example, it can be 32.5:1, 50:1, 60:1, 80:1, 100:1, 160:1, or a range formed by any two of the above values, such as (32.5-50):1, (32.5-80):1, (80-100):1, (100-160):1, and the like. Through the above setting, the matching effect of the positive active material and the negative active material can be further improved, the kinetic performance of the battery monomer can be improved, and the internal resistance can be reduced.

[0067] In an embodiment, the range of B is 0.1%-5%. For example, it can be 0.1%, 1%, 2%, 4%, 5%, or a range formed by any two of the above values, such as 1%-2%, 2%-5%, and the like. By limiting the proportion of the first negative active material in the negative active material within the above range, the capacity of the negative electrode sheet can be improved, and the problem of poor kinetic performance caused by the high-capacity negative active material can be alleviated.

[0068] Preferably, the range of B is 0.5%-2%. For example, it can be 0.5%, 0.6%, 1%, 1.5%, 2%, or a range formed by any two of the above values, such as 0.5%-0.6%, 1%-1.5%, 1.5%-2%, and the like. Through the above setting, the accuracy of the first negative active material addition amount can be improved, the capacity of the negative electrode sheet can be improved, and the problem of poor kinetic performance caused by the high-capacity negative active material can be alleviated.

[0069] In an embodiment, the negative active layer further comprises a carbon-based negative material, such as a graphite material; that is, the negative active layer comprises a mixture of multiple materials, such as a mixture of a silicon material and a graphite material. Alternatively, the negative active layer does not consist entirely of a negative active material with a capacity greater than 375 mAh / g, but can also contain an active material with a relatively low capacity, such as a graphite material (discharge capacity of about 320-380 mAh / g, charge capacity of about 350-400 mAh / g). The carbon-based negative material refers to a negative material with carbon as the main component, including graphite, carbon black, etc., and has a longer cycle life, higher safety, and relatively low price, but has a lower capacity (the theoretical gram capacity of carbon is about 372 mAh / g); the silicon-based negative material refers to a negative material with silicon as the main component, has a high capacity (the theoretical gram capacity of silicon is about 4200 mAh / g), good safety, and abundant reserves, but has low stability and poor kinetics. In the mixed material, the content of the silicon material is controlled to be 0.01%-5.5%. By mixing the carbon-based material and the silicon-based material, the capacity and stability of the negative electrode sheet can be improved. Different negative active materials can be selected according to the selection of the positive active material.

[0070] In an embodiment, A is in the range of 50%-95%. For example, it can be 50%, 55%, 60%, 80%, 90%, 95%, or a range composed of any two of the above values, such as 50%-60%, 55%-80%, 90%-95%, etc. By limiting the proportion of the ternary material in the positive active material to the above range, the kinetics of the positive electrode sheet is improved, the safety of the positive electrode sheet is improved, the energy density is improved, the cost is reduced, and the controllability of the production process is improved.

[0071] Preferably, A is in the range of 65%-80%. For example, it can be 65%, 67%, 72%, 75%, 80%, or a range composed of any two of the above values, such as 65%-67%, 67%-75%, 75%-80%, etc. By the above setting, the accuracy of the amount of ternary material added can be improved, the positive kinetics can be further improved, the deterioration of the negative kinetics can be alleviated, and the internal resistance of the battery cell can be improved.

[0072] In the formula, the positive active material at least includes two types of positive active materials, for convenience, the two types of positive active materials are referred to as the first positive active material and the second positive active material, and the ternary material is referred to as the first positive active material.

[0073] In an embodiment, the second positive active material comprises a polyanion type phosphate compound. The polyanion type phosphate compound type positive active material has a phosphate ion (PO4 3-) is the main structural unit, including lithium iron phosphate LiFePO4, also known as lithium iron phosphate (LFP); lithium manganese iron phosphate (LMAP) and the like. The polyanionic phosphate compound has good thermal stability and structural stability, which helps to improve the safety of the battery; generally shows good cycle life, is relatively stable in charge and discharge cycles, and can maintain a long battery life; the preparation process is relatively simple, and the raw materials are relatively inexpensive. The polyanionic phosphate compound is mixed with the ternary material in a proper ratio, which is conducive to the exertion of the advantages of the two positive electrode active materials, can improve the energy density of the positive electrode active material, improve the safety performance of the positive electrode sheet, and at the same time reduce the material cost.

[0074] In an embodiment, the positive electrode active material of the positive electrode active layer at least includes nickel element and cobalt element, wherein the total amount of nickel element and cobalt element accounts for 23%-35% of the total amount of metal elements in the positive electrode active material of the positive electrode active layer. For example, it can be 23%, 25%, 28%, 31%, 33%, 35%, or a range composed of any two of the above values, such as 23%-28%, 28%-31%, 31%-35%, etc.

[0075] In an embodiment, the positive electrode active layer includes a first ternary material, and the first ternary material at least includes nickel element, wherein the mass fraction of nickel element in the total amount of metal elements is ≥0.7.

[0076] In an embodiment, the positive electrode active layer includes a first ternary material, and the first ternary material at least includes nickel element, wherein the mass fraction of nickel element in the total amount of metal elements is ≥0.7.

[0077] The ternary material type positive electrode active material refers to a compound containing nickel (Ni), cobalt (Co), and manganese (Mn) (NCM), or a compound containing nickel (Ni), cobalt (Co), and aluminum (Al), including lithium nickel cobalt manganese oxide material (NCM) and the like. Due to the combination of the advantages of different metal elements and the relatively high voltage platform, the ternary material type positive electrode active material generally has a high energy density; at the same time, the kinetic performance is better. Each element in the ternary material plays an important role, and at the same time, the characteristics of each element also restrict the battery performance. Taking nickel cobalt manganese ternary material as an example: Ni shows high capacity and low safety; Co shows high cost and high stability, Co can stabilize the layered structure of the material, and can improve the cycle and rate performance of the material; Mn shows high safety and low cost.

[0078] Specifically, the increase of the content of nickel element can improve the capacity, but high-nickel material can reduce the cycle life and stability; manganese is electrochemically inert, and the increase of the content of manganese element can improve the structural stability and safety performance, but too high content is easy to appear spinel form, which can destroy the layered structure of the material and reduce the capacity; cobalt element can not only stabilize the layered structure of the material, but also reduce the cation mixing, which is beneficial to the cycle performance of the battery and the conductivity of the material, but too high content can reduce the reversible lithium intercalation capacity and increase the cost. By designing the ratio of the three elements, different nickel-cobalt-manganese ternary materials with different performances can be obtained. When the first kind of ternary material with high nickel content is selected as the positive active layer, the larger the capacity of the positive active layer is, the better the kinetic performance is, and more content of silicon-based material can be matched on the negative side.

[0079] In an embodiment, the positive active layer comprises the third kind of ternary material, and the third kind of ternary material comprises at least cobalt element, wherein the mass ratio of the cobalt element in the total amount of metal elements is 3%-15%. For example, it can be 3%, 5%, 8%, 10%, 12%, 15%, or a range formed by any two of the above values, such as 3%-5%, 3%-8%, 10%-12%, 12%-15%, etc.

[0080] Among them, the kinetics of the ternary material is good, the Co content can affect the NCM kinetics level, and adjusting the Co content in the ternary material can enhance the rate performance of the ternary material and improve the kinetic performance. Therefore, appropriately increasing the proportion of cobalt element can significantly improve the kinetic performance of the positive active material, thereby effectively alleviating the deterioration of the negative kinetics and improving the internal resistance of the battery cell. At the same time, considering the battery capacity and material cost, the proportion of cobalt element should not be too high, which should not exceed 30%.

[0081] In an embodiment, the positive active layer comprises the first kind of polyanion material, and the first kind of polyanion material comprises manganese element, wherein the mass ratio of the manganese element in the total amount of metal elements is 0.05-0.75; optionally, the mass ratio of the manganese element in the total amount of metal elements is 0.15-0.65. For example, it can be 0.05, 0.08, 0.10, 0.13, 0.15, 0.18, 0.20, 0.23, 0.25, 0.28, 0.30, 0.33, 0.35, 0.38, 0.40, 0.43, 0.45, 0.48, 0.50, 0.53, 0.55, 0.58, 0.60, 0.63, 0.65, 0.68, 0.70, 0.73, 0.75, etc.

[0082] The content of Mn in the polyanion material is limited, which can effectively improve the conductivity of the positive active layer. The increase of the content of Mn will reduce the conductivity of the polyanion material to some extent, and will worsen the internal resistance of the positive active layer. Therefore, the mass fraction of manganese in the total amount of metal elements in the first polyanion material is controlled to be 0.05-0.75, so as to improve the internal resistance of the battery cell.

[0083] In an embodiment, the positive active layer comprises a compound Li 1+x Mn 1-y A y P 1-z E z O4, wherein x is any number in the range of -0.100-0.100, y is any number in the range of 0.001-1.000, z is any number in the range of 0.001-0.100, A is one or more elements selected from Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb and Ge, and E is one or more elements selected from B, Si, N, S, F, Cl and Br.

[0084] Through the above settings, the values of x, y and z satisfy the following conditions: to keep the chemical formula electrically neutral. The element A doped at the manganese site of lithium manganese iron phosphate helps to reduce the lattice change rate of lithium manganese iron phosphate during lithium extraction, improve the structural stability of lithium manganese iron phosphate positive material, greatly reduce the dissolution of manganese and reduce the oxygen activity on the surface of the particles. The element E doped at the phosphorus site helps to change the difficulty of the change of Mn-O bond length, thereby reducing the lithium ion migration barrier, promoting lithium ion migration, and improving the rate performance of the battery cell.

[0085] In an embodiment, A is one or more elements selected from Fe, Ti, V, Ni, Co and Mg; and / or E is one element selected from B, Si, N and S. Through the above settings, the structural stability of the positive active material and the rate performance of the battery cell can be further improved.

[0086] In an embodiment, the positive active material has a core-shell structure, and the functional coating layer of the core-shell structure is one or more layers of pyrophosphate, phosphate, or carbon. With this arrangement, the dissolution of transition metal can be effectively inhibited due to the high migration barrier (>1eV) of transition metal in pyrophosphate. The phosphate has excellent lithium ion conductivity and can reduce the content of surface lithium impurities. The carbon layer can effectively improve the conductivity and desolvation ability of LiMnPO4, and also can play a "barrier" role to further hinder the migration of manganese ions into the electrolyte and reduce the corrosion of the electrolyte to the active material; at the same time, the carbon layer in the mixture can also optimize the conductive network around the ternary material, and improve the mixing uniformity of the phosphate-based positive active material and the ternary material.

[0087] When the first negative active material includes a silicon-based negative active material, the silicon-based negative active material itself has poor conductivity, and the severe volume change that occurs during the charging and discharging cycle of the battery eventually leads to the rapid irreversible degradation of the conductive network in the negative electrode sheet, resulting in capacity loss. Research has found that the active material, conductive agent, current collector, etc. in the negative active layer can be maintained by the binder to maintain effective electrical contact between them and maintain the integrity of the conductive network in the electrode and the stability of the charging and discharging cycle, thereby effectively alleviating the rapid decay of the silicon-based negative capacity and prolonging the cycle life of the battery.

[0088] In an embodiment, the negative active layer further includes a binder, and the mass fraction of the binder based on the total mass of the negative active layer is C; wherein the range of C:B is (0.17-2):1. For example, it can be (0.17:1), (0.2:1), (0.5:1), (1:1), (2:1), etc., or a range composed of any two of the above values, which can be (0.17-0.2):1, (0.17-0.5):1, (0.2-0.5):1, (1-2):1, etc.

[0089] The content of the binder increases with the content of the silicon-based negative active material, which promotes the adhesion between the silicon materials, is conducive to improving the electrical contact of the negative electrode sheet, maintaining the integrity of the conductive network in the negative electrode sheet and the stability of the charging and discharging cycle, and thus improving the internal resistance of the battery monomer.

[0090] In an embodiment, the range of C is 1%-3%. For example, it can be 1%, 1.2%, 1.5%, 2%, 2.8%, 3%, etc., or a range composed of any two of the above values, which can be 1%-1.2%, 1.2%-1.5%, 2%-2.8%, 2.8%-3%, etc. The content of the binder is within the above range, which further improves the matching degree of the content of the binder and the first negative active material, can form a good conductive network, promote more effective conduction of electrons, and thus improve the electrical conductivity of the electrode and reduce the internal resistance of the battery monomer.

[0091] The battery provided in the present application includes the battery monomer provided in any of the above embodiments.

[0092] The present application also provides an electrochemical device, which includes the battery provided in the present application.

[0093] In some embodiments, the use of the electrochemical device of the present application is not particularly limited, and it can be used in any electronic device known in the prior art. The battery disclosed in the embodiments of the present application can be used in a power consumption device using a battery as a power source or a variety of energy storage systems using a battery as an energy storage element. That is, a power consumption device is provided, and in some embodiments, the power consumption device of the present application can be used, but is not limited to, a notebook computer, a pen input computer, a mobile computer, an electronic book player, a portable telephone, a portable facsimile machine, a portable copying machine, a portable printer, a head-mounted stereo headphone, a video recorder, a liquid crystal television, a portable cleaner, a portable CD player, a mini disc, a transceiver, an electronic organizer, a calculator, a memory card, a portable recorder, a radio, a backup power supply, an electric motor, an automobile, a motorcycle, a power-assisted bicycle, a bicycle, a ship, a spacecraft, a lighting appliance, a toy, a game machine, a clock, an electric tool, a flashlight, a camera, a household large storage battery, and a lithium ion capacitor, etc.

[0094] The power consumption device can select a battery monomer, a battery module or a battery pack according to its use requirements.

[0095] Please refer to FIG. 3, which is a structural schematic diagram of a vehicle according to one or more embodiments. The vehicle 1000 can be a fuel automobile, a gas automobile or a new energy automobile, and the new energy automobile can be a pure electric automobile, a hybrid electric automobile or a range extended automobile, etc. The vehicle 1000 is internally provided with a battery 100, which can be arranged at the bottom, the head or the tail of the vehicle 1000. The battery 100 can be used for power supply of the vehicle 1000, for example, the battery 100 can be used as an operating power source of the vehicle 1000. The vehicle 1000 can further include a controller 200 and a motor 300, and the controller 200 is used to control the battery 100 to supply power to the motor 300, for example, for the working power demand of the vehicle 1000 during starting, navigation and driving.

[0096] In some embodiments of the present application, the battery 100 can not only be used as an operating power source of the vehicle 1000, but also be used as a driving power source of the vehicle 1000, instead of or partially instead of fuel or natural gas to provide driving power for the vehicle 1000.

[0097] The beneficial effects of the present application are further illustrated below in combination with embodiments.

[0098] In order to make the technical problems, technical solutions and beneficial effects solved by the embodiments of the present application clearer, the following will be further described in detail in combination with the embodiments and drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. The description of the at least one exemplary embodiment below is actually only illustrative, but not as any limitation on the present application and its application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0099] I. Preparation of battery monomer

[0100] Embodiment 1:

[0101] (1) Preparation of positive electrode sheet

[0102] The positive electrode active material, polyvinylidene fluoride (PVDF) and conductive carbon are added into a certain amount of N-methyl pyrrolidone (NMP), the positive electrode active material is a mixed material of ternary material and manganese iron lithium phosphate, the ternary material is a 5-series ternary material, the nickel accounts for 55% of the total mass of metal elements, the cobalt accounts for 5% of the total mass of metal elements, and the manganese accounts for 40% of the total mass of metal elements, the manganese in the manganese iron lithium phosphate accounts for 60% of the total mass of metal elements, and the mass ratio of the positive electrode active material, the binder and the conductive agent is 96:3:1. A uniform slurry is prepared by stirring in a drying room, and the viscosity is controlled to be 3000 mPa·S-10000 mPa·S. The above slurry is coated on the positive electrode substrate, and the positive electrode sheet is prepared after drying treatment.

[0103] (2) Preparation of negative electrode sheet

[0104] The negative electrode active material, carboxymethyl cellulose sodium (CMC), styrene butadiene rubber (SBR) and conductive carbon are added into a certain amount of deionized water, the negative electrode active material is a mixed material of graphite and silicon-oxygen material, the specific capacity of the silicon-oxygen material is 406 mAh / g, and the mass ratio of the negative electrode active material, carboxymethyl cellulose sodium, styrene butadiene rubber and conductive agent is 97:1:1:1. A uniform slurry is prepared by stirring, and the viscosity is controlled to be 3000 mPa·S-10000 mPa·S. The above slurry is coated on the copper foil, and the negative electrode sheet is prepared after drying treatment.

[0105] (3) Preparation of battery monomer

[0106] The prepared positive electrode sheet, negative electrode sheet and separator (polyethylene porous polymer film) are wound to form a corresponding battery monomer, the battery monomer is hot-pressed at 90°C, and then the positive and negative electrode tabs are ultrasonically welded, the positive electrode uses an aluminum tab, the negative electrode uses a copper tab, the positive and negative electrode tabs are located on the same side of the battery monomer, the battery monomer after tab welding is loaded into an aluminum shell of appropriate size for soft linking and top cover welding, the battery monomer is vacuum dried at 175°C for 24 hours, then electrolyte is injected and sealed to obtain a non-charged battery. The non-charged battery is sequentially subjected to the processes of standing, formation, aging, degassing, two-sealing, capacity testing and the like to obtain a lithium ion battery product.

[0107] Example 2-8:

[0108] The proportion of active materials in the positive electrode sheet and the negative electrode sheet is changed based on Example 1, and the details are shown in Table 1.

[0109] Comparative Example 1:

[0110] The proportion of active materials in the positive electrode sheet and the negative electrode sheet is changed based on Example 1, and the details are shown in Table 1.

[0111] II. Performance Test

[0112] (1) Internal resistance test

[0113] The internal resistance of the battery is measured by a battery internal resistance tester (Anber ATS21 model). After the battery internal resistance tester probe is clamped on both sides of the battery for 5 seconds, the resistance value is read when the tester reading is stable.

[0114] (2) Element (nickel, cobalt, manganese, silicon) content test in active material

[0115] ICP (Inductive Coupled Plasma Emission Spectrometer) is used for testing. The specific operation is as follows: the powder to be tested is placed in a microwave digestion instrument (such as CEM-Mars6) for digestion, and the solution after digestion is introduced into an ICP tester (such as ICAP7400), and the element content in the material is calculated by comparing the element concentration in the standard solution.

[0116] ICP can also calculate the proportion of two materials in the mixed positive electrode. By dividing the ICP test result by the element molar mass, the corresponding proportion of each element can be calculated, and then the proportion of each material can be determined, and then the proportion of each element in the NCM material can be calculated.

[0117] The battery is disassembled to obtain the electrode sheet, the coating layer material of the electrode sheet is scraped, and the binder, dispersant and other organic materials in the material are removed by using an organic solvent or by burning to obtain inorganic materials containing active materials; the scanning electron microscope analysis or the particle size analysis is used to determine that the material contains several active materials, and the material type is qualitatively determined; the content of part of characteristic elements in the material is tested, and the proportion of each material is calculated according to the element content. For the negative electrode sheet, the proportion of the silicon negative electrode can be obtained by testing the content of carbon element and silicon element; for the positive electrode sheet, if it is a mixed positive electrode of lithium iron phosphate and lithium manganese iron phosphate, the proportion of lithium iron phosphate and lithium manganese iron phosphate can be calculated according to the content of manganese element and iron; for the ternary material, the content of the ternary material can be calculated according to the content of nickel element.

[0118] (3) Binder content test

[0119] Thermogravimetric Analysis-Mass Spectrometry (TG-MS) is an analytical technique that combines thermogravimetric analysis (TGA) with mass spectrometry (MS); TGA is used to measure the mass change of a sample during heating or cooling, while MS is used to detect the gases or volatile substances released by the sample; the electrode sheet is disassembled to test the binder content by using a TG-MS thermal gravimetric analyzer.

[0120] III. Test result analysis

[0121] Table 1 Structure and performance of battery cells of each example and comparative example

[0122] Note: "positive electrode material" refers to the positive active material contained in the positive active layer; "negative electrode material" refers to the negative active material contained in the negative active layer, A is the mass proportion of ternary material in the positive active material, B is the mass proportion of silicon-oxygen material in the negative active material, NCM is a 5-series ternary material, nickel accounts for 55% of the total mass of metal elements in the 5-series ternary material, cobalt accounts for 5% of the total mass of metal elements, and manganese accounts for 40% of the total mass of metal elements; LMAP is lithium manganese iron phosphate, manganese accounts for 60% of the total mass of metal elements in lithium manganese iron phosphate, and the internal resistance is the internal resistance of the battery cell.

[0123] As can be seen from the above example results, by adjusting the mixing type and proportion of the positive active material and the negative active material, the kinetic performance of the battery cell can be improved and the internal resistance can be reduced.

[0124] Examples 9-13:

[0125] On the basis of Example 2, the proportion of active material and binder in the negative electrode sheet is changed, which is shown in detail in Table 2.

[0126] Comparative Example 2:

[0127] The proportion of active material and binder in the negative electrode sheet was changed based on Example 2, and the details are shown in Table 2.

[0128] Structure and performance of the battery cells of each example and comparative example in Table 2

[0129] Note: "positive electrode material" refers to the positive electrode active material contained in the positive electrode active layer; "negative electrode material" refers to the negative electrode active material contained in the negative electrode active layer, C is the mass percentage of the binder in the negative electrode active layer, B is the mass percentage of the silicon-oxygen material in the negative electrode active material, NCM is a 5-series ternary material, the nickel content in the 5-series ternary material accounts for 55% of the total mass of metal elements, the cobalt content accounts for 5% of the total mass of metal elements, and the manganese content accounts for 40% of the total mass of metal elements; LMAP is lithium manganese iron phosphate, the manganese content in lithium manganese iron phosphate accounts for 60% of the total mass of metal elements, and the internal resistance is the internal resistance of the battery cell.

[0130] As can be seen from the above example results, by adjusting the content of the binder and the first negative electrode active material on the negative electrode sheet, the electrical contact of the negative electrode sheet can be improved, the integrity of the conductive network in the negative electrode sheet can be maintained, the capacity decay of the negative electrode sheet can be alleviated, the internal resistance can be reduced, and the storage life and cycle life of the battery cell can be prolonged. However, if the amount of binder added is too much, the amount of insulating components will also be too much, and the internal resistance will also increase.

[0131] Examples 14-18:

[0132] The proportion of metal elements in the positive electrode active material in the positive electrode sheet was changed based on Example 2, and the details are shown in Table 3.

[0133] Comparative Example 3:

[0134] The proportion of metal elements in the positive electrode active material in the positive electrode sheet was changed based on Example 2, and the details are shown in Table 3.

[0135] Structure and performance of the battery cells of each example and comparative example in Table 3

[0136] Note: "positive electrode material" refers to the positive electrode active material contained in the positive electrode active layer; "negative electrode material" refers to the negative electrode active material contained in the negative electrode active layer, NCM is a 5-series ternary material, the nickel content in the 5-series ternary material accounts for 55% of the total mass of metal elements, the cobalt content accounts for 5% of the total mass of metal elements, and the manganese content accounts for 40% of the total mass of metal elements; LMAP is lithium manganese iron phosphate, the manganese content in lithium manganese iron phosphate accounts for 60% of the total mass of metal elements, the (Ni+Co) content in the positive electrode sheet refers to the total amount of nickel and cobalt elements accounting for the mass percentage of the total amount of metal elements in the positive electrode active material, and the internal resistance is the internal resistance of the battery cell.

[0137] The above embodiment results show that appropriately increasing the ratio of cobalt element and nickel element can significantly improve the kinetic performance of the positive active material, thereby effectively alleviating the negative kinetic deterioration and improving the battery cell internal resistance.

[0138] The above is only an embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation using the content of the present application specification and drawings, or direct or indirect application in other related technical fields, is also included in the patent protection scope of the present application.

Claims

1. A battery cell, wherein, Comprise: a positive electrode tab comprising a positive electrode active layer, the positive electrode active layer comprising a positive electrode active material, the positive electrode active material comprising at least a ternary material, a mass fraction of the ternary material being A based on a total mass of the positive electrode active material in the positive electrode active layer; a negative electrode tab comprising a negative electrode active layer, the negative electrode active layer comprising a first negative electrode active material, a capacity of the first negative electrode active material being greater than 375 mAh / g, a mass fraction of the first negative electrode active material being B based on a total mass of the negative electrode active material in the negative electrode active layer; wherein a range of A:B is (10-200):

1.

2. The battery cell of claim 1, wherein, The range of A:B is (32.5-160):

1.

3. The battery cell according to any one of claims 1 or 2, wherein, the range of B is 0.1%-5%; and / or the range of A is 50%-95%.

4. The battery cell according to claim 3, wherein, the range of B is 0.5%-2%; and / or the range of A is 65%-80%.

5. The battery cell according to any one of claims 1 to 4, wherein, the positive electrode active material in the positive electrode active layer comprises at least a nickel element and a cobalt element, wherein a total amount of the nickel element and the cobalt element accounts for a mass fraction of 23%-35% of a total amount of metal elements in the positive electrode active material of the positive electrode active layer.

6. The battery cell according to any one of claims 1 to 5, wherein, the positive electrode active layer comprises a first ternary material, the first ternary material comprising at least a nickel element, wherein a mass fraction of the nickel element in a total amount of metal elements is greater than 0.7; and / or the positive electrode active layer comprises a second ternary material, the second ternary material comprising at least a nickel element, wherein a mass fraction of the nickel element in a total amount of metal elements is 0.3-0.

7.

7. The battery cell according to any one of claims 1 to 6, wherein, the positive electrode active layer comprises a third ternary material, the third ternary material comprising at least a cobalt element, wherein a mass fraction of the cobalt element in a total amount of metal elements is 5%-30%.

8. The battery cell according to any one of claims 1 to 7, wherein, the positive electrode active layer comprises a first polyanion material, the first polyanion material comprising a manganese element, wherein a mass fraction of the manganese element in a total amount of metal elements is 0.05-0.

75.

9. The battery cell according to claim 8, wherein, the mass fraction of the manganese element in a total amount of metal elements in the first polyanion material is 0.15-0.

65.

10. The battery cell according to any one of claims 1 to 9, wherein, the first negative electrode active material comprises a silicon-based negative electrode material.

11. The battery cell according to any one of claims 1 to 10, wherein, the negative electrode active layer further comprises a binder, a mass fraction of the binder being C based on a total mass of the negative electrode active layer; wherein a range of C:B is (0.17-2):

1.

12. The battery cell of claim 11, wherein, the range of C is 1%-3%.

13. The battery cell according to any one of claims 1 to 12, wherein, The positive electrode active layer further includes a compound of formula Li 1+x Mn 1-y A y P 1-z E z O4, wherein x is any number in the range of -0.100 to 0.100, y is any number in the range of 0.001 to 1.000, z is any number in the range of 0.001 to 0.100, A is selected from one or more elements of Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb, and Ge, and E is selected from one or more elements of B, Si, N, S, F, Cl, and Br.

14. The battery cell according to claim 13, wherein, said A is selected from one or more elements of Fe, Ti, V, Ni, Co and Mg; and / or said E is selected from one element of B, Si, N and S.

15. The battery cell according to claim 13 or 14, wherein, The positive electrode active material has a core-shell structure, the cladding shell layer of the core-shell structure includes one or more layers of pyrophosphate, phosphate, carbon, the core layer of the core-shell structure includes active material Li 1+x Mn 1-y A y P 1-z E z O4.

16. A battery, wherein, comprising a battery cell as defined in any one of claims 1 to 15.

17. An electrical device, comprising: comprising a battery as defined in claim 16.

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