Battery cell, battery device, and electric device

Abstract

This application discloses a battery cell, a battery device, and an electrical appliance. The battery cell includes a positive electrode, which includes a positive current collector and a positive electrode film layer located on at least one side of the positive current collector. The positive electrode film layer includes lithium iron phosphate material and a lithium replenishing agent. Under the condition of discharging the battery to 2.5V at a rate of 0.04C, the lithium content is 4.0%-4.3% based on the total mass of the positive electrode film layer; a negative electrode; and a separator membrane located between the positive and negative electrode. Thus, a battery cell with both good cycle performance and energy density is obtained.

Description

[0001] This application is a divisional application of the invention patent application with application number 202411162604.6, application date August 22, 2024, entitled "Battery cell, battery device and electrical equipment". Technical Field

[0002] This application relates to the field of batteries, specifically to battery cells, battery devices, and electrical equipment. Background Technology

[0003] Batteries are used in energy storage power systems such as hydropower, thermal power, wind power, and solar power plants, and are also widely used in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in military equipment and aerospace. The two core requirements for energy storage batteries are high safety and long lifespan. However, the capacity of individual battery cells in related technologies decays rapidly in the early stages, which cannot meet customers' increasingly demanding requirements for lifespan. Summary of the Invention

[0004] The first aspect of this application provides a battery cell comprising a positive electrode, the positive electrode comprising a positive current collector and a positive electrode film layer located on at least one side of the positive current collector, the positive electrode film layer comprising lithium iron phosphate material and a lithium replenishing agent, wherein, under the condition of discharging the battery cell to 2.5V at a rate of 0.04C, the lithium content is 4.0%-4.3% based on the total mass of the positive electrode film layer; a negative electrode comprising a negative current collector and a negative electrode film layer located on at least one side of the negative current collector, the negative electrode film layer comprising a negative electrode active material, the negative electrode active material comprising graphite; and a separator located between the positive electrode and the negative electrode. Thus, a battery cell with both good cycle performance and energy density is obtained.

[0005] According to some embodiments of this application, when the battery cell is discharged to 2.5V at a rate of 0.04C, the lithium content is 4.0%-4.2% based on the total mass of the positive electrode film. This improves both the cycle performance and energy density of the battery cell.

[0006] According to some embodiments of this application, when the battery cell is discharged to 2.5V at a rate of 0.04C, the lithium content is 4.0%-4.1% based on the total mass of the positive electrode film. This improves both the cycle performance and energy density of the battery cell.

[0007] According to some embodiments of this application, a first gap, ranging from 50 nm to 500 nm, is formed between the lithium iron phosphate material and the lithium replenishing agent on a longitudinal section along the thickness direction of the positive electrode sheet. This improves the wetting effect of the electrolyte on the positive electrode sheet and enhances the kinetic performance of the battery cell.

[0008] According to some embodiments of this application, the positive electrode film layer includes at least the following lithium replenishing agent and lithium iron phosphate material: on a longitudinal section along the thickness direction of the positive electrode sheet, the average longest diameter of the lithium replenishing agent is *a*, and the average longest diameter of the lithium iron phosphate material is *b*, satisfying: 5 μm ≤ ab ≤ 11 μm. This increases the particle size of the lithium replenishing agent and decreases the particle size of the lithium iron phosphate material, thereby reducing side reactions of the lithium replenishing agent and improving the conductivity of the positive electrode active material.

[0009] According to some embodiments of this application, 1μm≤b≤2μm, 7μm≤a≤12μm. Therefore, by keeping a and b within the above ranges, the conductivity of the positive electrode active material is improved.

[0010] According to some embodiments of this application, the lithium supplement includes a matrix comprising Li x N y O z Where 1≤x≤6, 1≤y≤6, 2≤z≤12, and N includes one or more of the elements Na, Ni, Co, Mn, Al, and Fe.

[0011] According to some embodiments of this application, the lithium replenishing agent includes a matrix, which includes one or both of Li2NiO2 and Li5FeO4.

[0012] According to some embodiments of this application, the lithium supplement includes a matrix comprising Li n NiO m and Li e FeO f One or two of them, wherein 0 < m ≤ 2, 0 ≤ n ≤ 2, 0 ≤ e ≤ 5, and 0 < f ≤ 4.

[0013] According to some embodiments of this application, the lithium replenishing agent includes a matrix, the matrix comprising NiO. m and Li p FeO q One or two of them, where 0 < m ≤ 2, 0 ≤ p ≤ 1, and 0 < q ≤ 2.

[0014] Therefore, the decomposition of lithium replenishment agents can compensate for the active lithium ions consumed in the formation of SEI, thereby improving the energy density of individual battery cells.

[0015] According to some embodiments of this application, the molar content of Li in the lithium replenishing agent is greater than the molar content of Li in the lithium iron phosphate material. This improves the lithium replenishment effect and increases the energy density of the battery cell.

[0016] According to some embodiments of this application, at least a portion of the surface of the substrate has a coating layer, the coating layer comprising one or more of the elements C, Al, Zr, P, S, Si, and B. This improves the stability and ionic conductivity of the lithium replenishing agent, thereby enhancing the kinetic performance of the battery cell.

[0017] According to some embodiments of this application, the thickness of the coating layer is 10nm-200nm. This improves the stability and ionic conductivity of the lithium replenishing agent, thereby enhancing the kinetic performance of the battery cell.

[0018] According to some embodiments of this application, a second gap, 5nm-50nm in size, is provided between the substrate and the coating layer. This second gap allows for the filling of more electrolyte, enhancing the electrolyte retention capacity of the positive electrode and reducing the internal resistance of the battery cell.

[0019] According to some embodiments of this application, the matrix includes a doping element, which includes one or more of Al, Mn, Ti, Ni, Si, B, S, and P. This improves the structural stability of the lithium replenisher and reduces side reactions between the lithium replenisher and the electrolyte.

[0020] According to some embodiments of this application, the mass percentage of the dopant element is 0.01%-0.2% based on the total mass of the matrix. This improves the structural stability of the lithium replenishing agent and reduces side reactions between the lithium replenishing agent and the electrolyte.

[0021] According to some embodiments of this application, N includes the element Fe, and the molar ratio of Fe atoms to O atoms in the lithium replenisher is 1:(2-2.5). Specifically, the lithium replenisher decomposes to release oxygen. The molar ratio of Fe atoms to O atoms varies with the degree of decomposition. The released oxygen opens the explosion-proof valve, thereby improving the safety of the battery cell.

[0022] According to some embodiments of this application, the positive electrode film layer further includes a conductive agent, which includes one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. This improves the conductivity of the positive electrode sheet.

[0023] According to some embodiments of this application, when the battery is charged to 4.5V at a rate of 0.05C, gas is generated in the battery cell, the gas including oxygen, and the mass percentage of oxygen is 30%-80% based on the total mass of the gas. Therefore, in the event of overcharging, the released oxygen can open the explosion-proof valve, improving the safety of the battery cell.

[0024] According to some embodiments of this application, the battery further includes: an electrolyte comprising a solvent, an electrolyte salt, and additives; the molar concentration of the electrolyte salt in the electrolyte is 1.1 mol / L-1.5 mol / L; the additives include one or more of phosphorus-containing additives, fluorine-containing additives, and sulfur-containing additives; and the solvent includes cyclic carbonates and linear carbonates. This reduces Li loss during the SEI film formation process, increases the energy density of the battery cell, and simultaneously improves the stability of the positive electrode active material and the SEI film, thereby enhancing the cycle performance of the battery cell.

[0025] The second aspect of this application provides a battery device, including the battery cell provided in the first aspect of this application.

[0026] A third aspect of this application provides an electrical device including a battery cell provided in the first aspect of this application, the battery cell being used to provide electrical energy.

[0027] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0028] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 A longitudinal section SEM image of the positive electrode sheet according to one embodiment of this application.

[0029] Figure 2 This is a schematic diagram of a battery cell according to one embodiment of this application.

[0030] Figure 3 yes Figure 2 An exploded view of a battery cell according to one embodiment of this application is shown.

[0031] Figure 4 This is a schematic diagram of a battery module according to one embodiment of this application.

[0032] Figure 5 This is a schematic diagram of a battery pack according to one embodiment of this application.

[0033] Figure 6 yes Figure 5 An exploded view of a battery pack according to one embodiment of this application is shown.

[0034] Figure 7 This is a schematic diagram of an electrical device using a battery device as a power source according to an embodiment of this application.

[0035] Explanation of reference numerals in the attached figures: 1 Battery pack; 2 Upper housing; 3 Lower housing; 4 Battery module; 5 Battery cell; 51 Housing; 52 Electrode assembly; 53 Cover plate; 6 Lithium iron phosphate particles; 71 Lithium replenishing agent matrix; 72 Lithium replenishing agent coating layer; 73 Second gap. Detailed Implementation

[0036] The embodiments of the technical solution of this application are described in detail below. The following embodiments are only used to illustrate the technical solution of this application more clearly, and are therefore only examples, and should not be used to limit the scope of protection of this application.

[0037] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0038] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0039] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0040] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0041] Currently, judging from the development of the market, batteries are being used more and more widely, and can be applied to energy storage power systems such as hydropower, thermal power, wind power and solar power plants. However, the energy storage batteries in related technologies cannot simultaneously meet the requirements of high energy density and long cycle life.

[0042] This application aims to develop battery cells with both excellent energy density and cycle performance. The energy density of the battery cell is improved by incorporating a lithium supplement in the positive electrode film. Furthermore, by controlling the lithium content in the positive electrode film under conditions of 0.04C discharge to 2.5V, the utilization rate of the positive electrode active material is improved, thereby increasing the cycle life of the battery cell.

[0043] The battery cells proposed in this application can be used in electrical devices that use the battery cells as a power source or in various energy storage systems that use the battery cells as energy storage elements. Electrical devices can include, but are not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Among them, electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc., and spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0044] The first aspect of this application discloses a battery cell, the battery cell comprising a positive electrode sheet, the positive electrode sheet comprising a positive current collector and a positive electrode film layer located on at least one side of the positive current collector, the positive electrode film layer comprising lithium iron phosphate material and a lithium replenishing agent, and wherein, under the condition of discharging the battery cell to 2.5V at a rate of 0.04C, the lithium content is 4.0%-4.3% based on the total mass of the positive electrode film layer; a negative electrode sheet, the negative electrode sheet comprising a negative current collector and a negative electrode film layer located on at least one side of the negative current collector, the negative electrode film layer comprising a negative electrode active material, the negative electrode active material comprising graphite; and a separator, the separator being located between the positive electrode sheet and the negative electrode sheet.

[0045] This application aims to develop a battery cell with both good cycle performance and energy density. By incorporating a lithium replenishing agent in the positive electrode film, the lithium loss caused by the formation of the SEI film during the formation stage is compensated, thereby improving the energy density of the battery cell. By controlling the lithium content in the positive electrode film within a suitable range under 0.04C discharge to 2.5V conditions, the number of lithium ions in the positive electrode film is increased, thereby improving the specific capacity of the positive electrode active material and enhancing the energy density and cycle life of the battery cell. Specifically, when the lower limit of the lithium content in the positive electrode film is below 4.0% under 0.04C discharge to 2.5V conditions, the battery cell cannot simultaneously achieve high energy density and cycle life; the upper limit of the lithium content in the positive electrode film under 0.04C discharge to 2.5V conditions is 4.3%. Further increasing the lithium replenishing agent content at this level, although resulting in better cycle performance, reduces the mass proportion of LFP material, thus lowering the energy density of the battery cell.

[0046] In this application, the lithium content is tested under the condition of discharging the battery cell to 2.5V at a rate of 0.04C as follows: after discharging the battery cell to 2.5V at a rate of 0.04C, the battery cell is disassembled, the positive electrode is removed and cleaned with dimethyl carbonate (DMC) solvent, dried and the positive electrode powder is scraped off, and the lithium content in the positive electrode can be tested using a Thermo ICAP7400 inductively coupled plasma-emitting emission spectrometer (ICP-OES).

[0047] As an example, under the condition of discharging the battery cell to 2.5V at a rate of 0.04C, the lithium content based on the total mass of the positive electrode film is 4.0%, 4.05%, 4.1%, 4.12%, 4.15%, 4.18%, 4.2%, 4.22%, 4.3%, etc., or can be any range of the above values.

[0048] According to some specific embodiments of this application, when the battery cell is discharged to 2.5V at a rate of 0.04C, the lithium content is 4.0%-4.2% based on the total mass of the positive electrode film. This improves both the cycle performance and energy density of the battery cell.

[0049] According to some specific embodiments of this application, when the battery cell is discharged to 2.5V at a rate of 0.04C, the lithium content is 4.0%-4.1% based on the total mass of the positive electrode film. This improves both the cycle performance and energy density of the battery cell.

[0050]

Positive Electrode

[0051] In some embodiments, the positive 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 substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0052] According to some embodiments of this application, a first gap exists between the lithium iron phosphate material and the lithium replenishing agent on a longitudinal section along the thickness direction of the positive electrode sheet. This first gap can be 50nm-500nm. Specifically, after the lithium iron phosphate material and the lithium replenishing agent are mixed, the first gap is formed at the interface between them. The presence of this first gap can improve the wetting effect of the electrolyte on the positive electrode sheet and enhance the kinetic performance of the battery cell.

[0053] In this application, the test method for the first gap is to use plasma to cut the positive electrode sheet along its thickness direction to obtain the cross-section of the positive electrode sheet, and to obtain the cross-sectional image by scanning electron microscopy (SEM observation). After selecting the lithium replenishing agent particles, it can be observed that there is a gap at the interface between them and the surrounding active particles. Then, the maximum distance between the edge of the lithium replenishing agent and the edge of the lithium iron phosphate material is measured, which is the size of the first gap.

[0054] As an example, the first gap can be 50nm, 100nm, 200nm, 300nm, 400nm or 500nm, or a range of any of the above values.

[0055] According to some embodiments of this application, on a longitudinal section along the thickness direction of the positive electrode sheet, the average value of the longest diameter of the lithium replenishing agent is 'a', and the average value of the longest diameter of the lithium iron phosphate material is 'b', satisfying the condition: 5μm≤ab≤11μm. Therefore, by ensuring that the difference between 'a' and 'b' is within the aforementioned range, a first gap is formed at the interface between the positive electrode active material and the lithium replenishing agent, thereby improving the wetting effect of the electrolyte on the positive electrode sheet.

[0056] As an example, ab can be 5μm, 6μm, 7μm, 8μm, 9μm, 10μm or 11μm, or a range of any of the above values.

[0057] The longest diameter of the lithium supplement and lithium iron phosphate material in this application is defined as follows: The positive electrode sheet, comprising lithium replenishing agent particles and lithium iron phosphate material, was cut along its thickness direction to expose the longitudinal section of the positive electrode film. Scanning electron microscopy (SEM) was used to analyze the longitudinal section of the positive electrode film to determine the longest diameters of the lithium replenishing agent and lithium iron phosphate material. Specifically, the longest diameter of the lithium replenishing agent is defined as the longest straight line passing through its center point and extending to the outer periphery of the particle; the longest diameter of the lithium iron phosphate material is defined as the longest straight line passing through its center point and extending to the outer periphery of the particle.

[0058] In this application, the average length of the longest diameter of the lithium supplement and the lithium iron phosphate material is calculated as follows: In the longitudinal section of the positive electrode film, arbitrarily select 30 lithium replenishing agent particles, measure the longest diameter of each of the 30 lithium replenishing agent particles, and take their average value; in the longitudinal section of the positive electrode film, arbitrarily select 30 lithium iron phosphate material particles, measure the longest diameter of each of the 30 lithium iron phosphate material particles, and take their average value.

[0059] According to some embodiments of this application, the average longest diameter of the lithium iron phosphate material can be 1 μm-2 μm, for example, it can be 1 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm or 2 μm, or any range of the above values. This reduces the particle size of the positive electrode active material, increases the rate of lithium ion extraction from the positive electrode active material, and improves the conductivity of the positive electrode active material.

[0060] According to some embodiments of this application, the average longest diameter of the lithium replenishing agent can be 7μm-12μm, for example, it can be 7μm, 7.5μm, 8μm, 8.5μm, 9μm, 9.5μm, 10μm, 10.5μm, 11μm, 11.5μm, or 12μm, or it can be any range of the above values. This increases the particle size of the lithium replenishing agent, reduces its specific surface area, reduces the number of active sites on the surface of the lithium replenishing agent, reduces side reactions between the lithium replenishing agent and the electrolyte, improves the stability of the electrolyte under high voltage conditions, and increases the lifespan of the battery cell.

[0061] According to some embodiments of this application, the lithium iron phosphate material includes lithium iron phosphate material with an olivine structure. Therefore, the positive electrode active material structure is relatively stable, reducing the probability of collapse of the positive electrode active material during battery cell cycling, and improving the stability and safety of the battery cell.

[0062] According to some embodiments of this application, the lithium supplement includes a matrix comprising Li x N y O zWhere 1≤x≤6, 1≤y≤6, 2≤z≤12, and N includes one or more of the elements Na, Ni, Co, Mn, Al, and Fe. Therefore, the decomposition of the lithium replenishment agent can compensate for the active lithium ions consumed in the formation of the SEI film, thereby improving the initial efficiency and energy density of the battery cell.

[0063] As an example, x can be 1, 2, 3, 4, 5 or 6, or a range of any of the above values.

[0064] As an example, y can be 1, 2, 3, 4, 5 or 6, or a range of any of the above values.

[0065] As an example, z can be 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, or a range of any of the above values.

[0066] According to some embodiments of this application, the lithium replenishing agent includes one or both of Li2NiO2 and Li5FeO4. This improves the lithium replenishment effect.

[0067] According to some embodiments of this application, when all or part of the lithium in the lithium replenishing agent is extracted, the lithium replenishing agent includes Li n NiO m and Li e FeO f One or two of them, wherein 0 < m ≤ 2, 0 ≤ n ≤ 2, 0 ≤ e ≤ 5, and 0 < f ≤ 4.

[0068] As an example, m can be 0.5, 1, 1.5 or 2, or a range of any of the above values.

[0069] As an example, n can be 0, 0.5, 1, 1.5 or 2, or a range of any of the above values.

[0070] As an example, e can be 0, 1, 2, 3, 4 or 5, or a range of any of the above values.

[0071] As an example, f can be 1, 2, 3, or 4, or a range of any of the above values.

[0072] According to some embodiments of this application, when all the lithium in the lithium replenishing agent is released, the lithium replenishing agent includes NiO. m and Li p FeO q One or two of them, where 0 < m ≤ 2, 0 ≤ p ≤ 1, and 0 < q ≤ 2.

[0073] As an example, m can be 0.5, 1, 1.5 or 2, or a range of any of the above values.

[0074] As an example, p can be 0, 0.2, 0.4, 0.6, 0.8 or 1, or a range of any of the above values.

[0075] As an example, q can be 0.5, 1, 1.5 or 2, or a range of any of the above values.

[0076] According to some embodiments of this application, when the lithium replenishing agent in the positive electrode film layer is not completely decomposed, the molar content of Li element in the lithium replenishing agent is greater than the molar content of Li element in the lithium iron phosphate material. According to some embodiments of this application, at least a portion of the surface of the substrate has a coating layer, which includes one or more of the elements C, Al, Zr, P, S, Si, and B. Therefore, the coating layer can reduce the probability of the substrate being in direct contact with air, reduce the probability of the substrate reacting with water and carbon dioxide in the air, improve the air stability of the substrate, reduce the formation of impurity lithium on the substrate surface, and simultaneously improve the conductivity of the substrate and increase the utilization rate of active lithium ions.

[0077] According to some embodiments of this application, the thickness of the coating layer can be 10nm-200nm. For example, it can be 10nm, 50nm, 100nm, 150nm, or 200nm, or any range of the above values. This reduces the probability of active lithium ion release due to excessive coating layer thickness, improves the decomposition efficiency of the substrate, and enhances the lithium replenishment effect.

[0078] In this application, the method for testing the thickness of the coating layer is to cut the positive electrode sheet, which includes lithium replenishing particles and lithium iron phosphate material, along the thickness direction of the electrode sheet to expose the longitudinal section of the positive electrode film. By performing SEM testing on the longitudinal section of the positive electrode film, after selecting the lithium replenishing particles, it can be observed that the lithium replenishing particles have a core-shell structure. The thickness of the shell layer is then measured as the thickness of the coating layer.

[0079] According to some embodiments of this application, after the lithium replenishment agent undergoes delithiation, the crystal lattice shrinks, and a second gap exists between the substrate and the coating layer. This second gap can be 5nm-50nm. For example, the second gap can be 5nm, 10nm, 20nm, 30nm, 40nm, or 50nm, or any range of the aforementioned values. This improves the liquid retention capacity of the positive electrode, enhances the transport efficiency of active lithium ions, and reduces the internal resistance of the battery.

[0080] In this application, the test method for the second gap involves cutting the positive electrode sheet, which includes lithium replenishing agent particles and lithium iron phosphate material, along the thickness direction of the electrode sheet to expose the longitudinal section of the positive electrode film. By performing SEM testing on the longitudinal section of the positive electrode film, after the lithium replenishing agent decomposes, a gap can be observed between the matrix of the lithium replenishing agent particles and the coating layer in the longitudinal section image. The maximum distance between the edge of the lithium replenishing agent matrix and the inner edge of the coating layer is measured, which is the size of the second gap. The existence of the second gap helps to ensure sufficient contact between the electrolyte and the lithium replenishing agent matrix during cycling, and facilitates the full release of lithium ions by the lithium replenishing agent.

[0081] refer to Figure 1 , Figure 1 This is a SEM image of a longitudinal section of the positive electrode sheet, including lithium iron phosphate particles 6 and lithium replenishing agent particles. The lithium replenishing agent particles are Li5FeO4. Figure 1 It can be seen that there is a second gap 73 between the lithium replenishing agent matrix 71 and the lithium replenishing agent coating layer 72.

[0082] According to some embodiments of this application, the substrate includes a dopant element, which includes one or more of Al, Mn, Ti, Ni, Si, B, S, and P. Therefore, the dopant element can improve the structural stability of the substrate, reduce the probability of the substrate structure being damaged by lithium ion extraction and thus generating grain boundary cracks, reduce side reactions between the substrate and the electrolyte, and reduce the dissolution of nitrogen from the substrate.

[0083] According to some embodiments of this application, the mass percentage of the dopant element can be 0.01%-0.2% based on the total mass of the substrate. For example, it can be 0.01%, 0.05%, 0.1%, 0.15%, or 0.2%, or any range of the above values. This improves the structural stability of the substrate.

[0084] According to some embodiments of this application, N includes the element Fe, and the molar ratio of Fe atoms to O atoms in the lithium replenisher is 1:(2-2.5). Specifically, the lithium replenisher decomposes to produce oxygen, and the molar ratio of Fe atoms to O atoms in the lithium replenisher varies depending on the degree of decomposition. Therefore, after the lithium replenisher decomposes and releases oxygen, when the internal pressure or temperature of the battery is too high, the oxygen can open the explosion-proof valve, improving battery safety. According to some embodiments of this application, the positive electrode film layer further includes a conductive agent. This improves the conductivity of the positive electrode film layer.

[0085] As an example, the conductive agent includes one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0086] In some embodiments, the positive electrode film layer may optionally include a binder. As an example, the binder may include at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0087] [Negative electrode plate] The negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector, the negative electrode film layer including a negative electrode active material.

[0088] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0089] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0090] In some embodiments, the negative electrode film layer may optionally include an adhesive. The adhesive may be selected from at least one 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).

[0091] In some embodiments, the negative electrode film may optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0092] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0093] In some embodiments, the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto a negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0094] [Electrolytes] The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not specify any particular type of electrolyte; it can be selected according to requirements.

[0095] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes a solvent, an electrolyte salt, and additives. The molar concentration of the electrolyte salt in the electrolyte solution is 1.1 mol / L to 1.5 mol / L. The additives include one or more of phosphorus-containing additives, fluorine-containing additives, and sulfur-containing additives. The solvent includes cyclic carbonates and linear carbonates.

[0096] According to some embodiments of this application, the molar concentration of the electrolyte salt in the electrolyte can be 1.1 mol / L-1.5 mol / L, for example, it can be 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L or 1.5 mol / L, or it can be any range of the above values.

[0097] In some embodiments, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0098] According to some embodiments of this application, the additive includes one or more of phosphorus-containing additives, fluorine-containing additives, and sulfur-containing additives. Based on the total mass of the electrolyte, the sum of the masses of the phosphorus-containing additive, the fluorine-containing additive, and the sulfur-containing additive can be 0.2%-2%, for example, 0.2%, 0.4%, 0.6%, 0.8%, 1%, 1.2%, 1.4%, 1.6%, 1.8%, or 2%, or a range of any of the above values.

[0099] According to some embodiments of this application, the phosphorus-containing additive includes one or more of lithium difluorophosphate (LiDFP), tris(trimethylsilane) phosphate (TMSP), triphenylphosphine oxide (TPPO), triethyl phosphate (TEP), trimethylolpropane (TMP), and ethylene trifluoroethyl phosphate (TFEOP).

[0100] According to some embodiments of this application, the fluorinated additive includes one or more of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), and perfluoroalkyl ethylene carbonate.

[0101] According to some embodiments of this application, the electrolyte further includes boron-containing additives, which include one or more of tris(trimethylsilane)borate (TMSB), lithium tetrafluoroborate (LiBF4), lithium dioxalate borate (LiBOB), and lithium difluorooxalate borate (LiDFOB).

[0102] According to some embodiments of this application, the sulfur-containing additive includes one or more of vinyl sulfite (ES), propylene sulfite (PS), vinyl sulfate (DTD), 4-methylethylene sulfate (PCS), and 1,3-propenesulfonyl lactone (PST).

[0103] According to some embodiments of this application, the additives also include carbonate additives.

[0104] According to some embodiments of this application, the carbonate additives include vinylene carbonate (VC).

[0105] According to some embodiments of this application, the solvent includes cyclic carbonates and linear carbonates, with the cyclic carbonates accounting for 15%-25% of the total mass of the electrolyte and the linear carbonates accounting for 50%-70% of the total mass. This improves the stability of the electrolyte.

[0106] According to some embodiments of this application, the cyclic carbonate includes at least one of ethylene carbonate (EC) or propylene carbonate.

[0107] According to some embodiments of this application, the linear carbonate includes at least one of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and diethyl carbonate.

[0108] [Isolation membrane] According to some embodiments of this application, the separator includes: a base film made of polyethylene; an adhesive layer located on at least one side of the base film; and a ceramic layer located on the side of the adhesive layer away from the base film. Thus, the adhesive layer reduces the probability of wrinkles in the base film, and the ceramic layer reduces the risk of puncture in the separator, improving battery safety.

[0109] According to some embodiments of this application, the separator is disposed between the positive electrode and the negative electrode, with the ceramic layer close to the positive electrode. This reduces the probability of the base film being oxidized under high voltage conditions.

[0110] [Battery cell] In some embodiments, the battery may include an outer packaging. This outer packaging may be used to encapsulate the electrode assembly and electrolyte described above.

[0111] According to some embodiments of this application, when the battery cell is charged to 4.5V at a rate of 0.05C, gas is generated in the battery cell, including oxygen, and the mass percentage of oxygen is 30%-80% based on the total mass of the gas. Therefore, when the battery is overcharged, the lithium replenishing agent decomposes to generate a large amount of oxygen, which can open the explosion-proof valve, improving the safety of the battery cell.

[0112] As an example, the oxygen content can be 30%, 40%, 50%, 60%, 70%, or 80%, or a range of any of the above values.

[0113] In this application, the method for testing oxygen content is to remove the liquid injection hole of the battery cell, collect the gas generated by 4.5V overcharging through an external gas tube, and measure the oxygen content in the gas using a JJG 700-1999 gas chromatograph.

[0114] In some implementations, the battery's outer packaging can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The battery's outer packaging can also be a soft pack, such as a pouch. The soft pack can be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0115] This application does not impose any particular limitation on the shape of the battery; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 2 The example shown is a square-structured battery cell 5.

[0116] In some implementations, refer to Figure 3 The outer packaging may include a housing 51 and a cover plate 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be placed over the opening to close the receiving cavity. The positive electrode sheet, negative electrode sheet, and separator can be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in a single battery cell 5 can be one or more, which can be selected by those skilled in the art according to specific practical needs.

[0117] In some implementations, the batteries can be assembled into battery modules, and the number of batteries contained in a battery module can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery module.

[0118] Figure 4 This is battery module 4, used as an example. (See reference...) Figure 4In battery module 4, multiple battery cells 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, these multiple battery cells 5 can be fixed in place using fasteners.

[0119] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple battery cells 5 are received.

[0120] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0121] The second aspect of this application provides a battery device, including the battery cell provided in the first aspect of this application.

[0122] Figure 5 and Figure 6 This is battery pack 1 as an example. (See reference...) Figure 5 and Figure 6 The battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper body 2 and a lower body 3, with the upper body 2 covering the lower body 3 to form a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0123] In addition, this application also provides an electrical device, which includes at least one of the battery cell, battery module, or battery pack provided in this application. The battery cell, battery module, and battery pack are used to provide electrical energy. The battery, battery module, or battery pack 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, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0124] As the electrical equipment, battery cells, battery modules, or battery packs can be selected according to their usage requirements.

[0125] Figure 7 This is an example of an electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the device's requirements for high power and high energy density batteries, a battery pack or battery module can be used.

[0126] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can be powered by a battery.

[0127] To make the technical problems, technical solutions, and beneficial effects solved by the embodiments of this application clearer, the following will provide a more detailed description in conjunction with the embodiments and accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its applications. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0128] Example 1 1. Positive electrode sheet The positive electrode sheet includes a positive current collector aluminum foil, with a positive electrode film layer on both surfaces. The thickness of the positive electrode film layer on one side is 100 μm, and the compaction density is 2.4 g / cm³. 3 The coating weight of the single-sided positive electrode film is 24 mg / cm³. 2 Based on the total mass of the single-sided positive electrode film, the positive electrode film includes lithium iron phosphate material accounting for 95.3% by mass, lithium supplementing agent Li5FeO4 (with carbon material coated on the surface, with a thickness of about 100nm, and the coating layer accounts for 2.5% by mass based on the total mass of the lithium supplementing agent), conductive agent carbon black, and binder polyvinylidene fluoride (PVDF) accounting for 1.8% by mass.

[0129] 2. Negative electrode plate The negative electrode sheet includes a negative current collector copper foil, with a negative electrode film layer on both surfaces. The thickness of the negative electrode film layer on one side is 57 μm, and the compaction density is 1.44 g / cm³. 3 The coating weight of the single-sided negative electrode film is 8.2 mg / cm³. 2 Based on the total mass of the single-sided negative electrode film, the negative electrode film includes 97.2% artificial graphite (94% graphitization degree), 0.8% conductive carbon black, 0.8% binder styrene-butadiene rubber (SBR), and 1.2% thickener sodium carboxymethyl cellulose (CMC-Na).

[0130] 3. Electrolyte The electrolyte comprises solvents, electrolyte salts, and additives. The solvents include EC, DMC, and EMC, with a mass ratio of 31:32:37. The electrolyte salt is LiPF6 with a molar concentration of 1.2 mol / L. The additives include LiDFP, FEC, LIDFOB, LiBF4, PS, and VC. Based on the total mass of the electrolyte, the mass percentages are as follows: LiDFP 0.039%, FEC 0.23%, LIDFOB 0.0246%, LiBF4 0.0091%, PS 0.54%, and VC 3.34%.

[0131] 4. Separating membrane Polyethylene film.

[0132] 5. Battery cell It includes the positive electrode, the separator, the negative electrode, and the electrolyte.

[0133] Performance testing 1. Energy density At 25℃, a lithium-ion battery was charged at a constant current of 1 / 3C to 3.65V, then charged at a constant voltage of 3.65V to a current of 0.05C. After resting for 5 minutes, it was discharged at 1 / 3C to 2.5V, and the discharge capacity was recorded as C. The volume of the battery cell was calculated as V after measuring its dimensions, thus its volumetric energy density was determined to be 3.22. C / V.

[0134] 2.45℃ Cyclic Capacity Retention At 45°C, the lithium-ion battery was charged at a constant current of 1 / 3C to 3.65V, charged at a constant voltage of 3.65V to a current of 0.05C, left to stand for 5 minutes, and then discharged at 1 / 3C to 2.5V. The discharge capacity C0 was recorded. (2) The lithium-ion battery was then charged at a constant current of 1.0C to 3.65V, left to stand for 5 minutes, and then discharged at 1 / 3C to 2.5V. The discharge capacity C1 was recorded. The above steps (2) were repeated 300 times, and the discharge capacity C of the lithium-ion battery after the 300th cycle was recorded. 300 Capacity retention rate P 300 =C 300 / C0×100%.

[0135] 3. Test method for lithium content in positive electrode film After discharging the battery cell to 2.5V at a rate of 0.04C, the battery cell is disassembled, the positive electrode is removed and cleaned with dimethyl carbonate (DMC) solvent, dried and the positive electrode powder is scraped off. The lithium content in the positive electrode can be tested using a Thermo ICAP7400 inductively coupled plasma-emission spectrometer (ICP-OES).

[0136] Examples 2-5 The negative electrode and electrolyte in the battery cell are the same as in Example 1, except that the content of lithium replenishing agent in the positive electrode film is different.

[0137] Comparative Example 1 The negative electrode and electrolyte in the battery cell are the same as in Example 1, except that the positive electrode film does not contain lithium replenishing agent.

[0138] Example 6 The negative electrode and electrolyte in the battery cell are the same as in Example 1, except that the type of lithium replenishing agent in the positive electrode film is different.

[0139] The differences between Examples 1-6 and Comparative Example 1 are detailed in Table 1.

[0140] Table 1

[0141] As can be seen from Examples 1-5, the battery cell proposed in this application has both high energy density and cycle capacity retention, indicating that by adding different masses of lithium supplementing agent to the positive electrode film, this application can adjust the lithium content in the positive electrode film and improve the cycle life and energy density of the battery cell.

[0142] As can be seen from the comparison of Example 1, Example 2 and Comparative Example 1, when there is no lithium replenishment agent in the positive electrode film, the energy density and cycle capacity retention of the battery cell are both low; when the lithium content in the positive electrode film is 1.5%-1.9%, compared with not adding lithium replenishment agent to the positive electrode film, the energy density and cycle performance of the battery cell can be improved at the same time.

[0143] As can be seen from Examples 3-5 and Comparative Example 1, as the lithium content in the positive electrode film gradually increases, the energy density of the battery cell decreases slightly, while the cycle performance gradually improves. This is because as the content of the lithium replenishing agent in the positive electrode film gradually increases, the mass proportion of lithium iron phosphate material gradually decreases, leading to a slight decrease in the energy density of the battery cell. However, it is still possible to obtain battery cells with an energy density greater than or equal to 410 Wh / L and a cycle capacity retention rate greater than or equal to 97.3%.

[0144] As can be seen from Examples 1-3, when the lithium content in the positive electrode film is 4.0%-4.2%, the energy density of the battery cell is greater than or equal to 420Wh / L and the cycle capacity retention rate is greater than or equal to 93%. This indicates that when the lithium replenishment content in the positive electrode film is 1.5%-2.5%, a battery cell with both high energy density and high cycle performance can be obtained.

[0145] As can be seen from Examples 1 and 6, different types of lithium replenishing agents can be selected, and the lithium content in the positive electrode film can be controlled by adjusting the amount of lithium replenishing agent added, thereby obtaining a battery cell with both good cycle performance and energy density.

[0146] Example 7, Example 8 The negative electrode and electrolyte in the battery cell are the same as in Example 1, except that the particle size of lithium iron phosphate is different.

[0147] Example 9, Example 10 The negative electrode and electrolyte in the battery cell are the same as in Example 1, except that the particle size of the lithium replenishing agent is different.

[0148] Example 11, Example 12 The negative electrode and electrolyte in the battery cell are the same as in Example 1, except that the thickness of the coating layer on the surface of the lithium replenishing agent is different.

[0149] The differences between Examples 7-12 are detailed in Table 2.

[0150] Table 2

[0151] As can be seen from Examples 7-10, when the lithium content in the positive electrode film is within a suitable range, positive electrode active materials and lithium supplements of different particle sizes can all yield battery cells with high energy density and cycle performance. Furthermore, adjusting the particle size of the positive electrode active material can increase the lithium insertion / extraction rate and improve the conductivity of the positive electrode active material; adjusting the particle size of the lithium supplement can reduce the specific surface area of ​​the lithium supplement and decrease side reactions between the lithium supplement and the electrolyte.

[0152] As can be seen from Examples 11 and 12, the surface of the lithium replenishing agent can also have a carbon coating layer of different thicknesses. By adjusting the thickness of the coating layer, the lithium ion extraction rate can be increased, thereby improving the lithium replenishment effect.

[0153] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized in that, include: A positive electrode sheet, comprising a positive current collector and a positive electrode film layer located on at least one side of the positive current collector, the positive electrode film layer comprising lithium iron phosphate material and a lithium replenishing agent, wherein, under the condition of discharging the battery cell to 2.5V at a rate of 0.04C, the lithium content is 4.0%-4.3% based on the total mass of the positive electrode film layer; On the longitudinal section along the thickness direction of the positive electrode sheet, there is a first gap between the lithium iron phosphate material and the lithium replenishing agent, the first gap being 50nm-500nm; A negative electrode sheet, the negative electrode sheet comprising a negative current collector and a negative electrode film layer located on at least one side of the negative current collector, the negative electrode film layer comprising a negative electrode active material, the negative electrode active material comprising graphite.

2. The battery cell according to claim 1, characterized in that, When the battery cell is discharged to 2.5V at a rate of 0.04C, the lithium content is 4.0%-4.2% based on the total mass of the positive electrode film.

3. The battery cell according to claim 1 or 2, characterized in that, When the battery cell is discharged to 2.5V at a rate of 0.04C, the lithium content is 4.0%-4.1% based on the total mass of the positive electrode film.

4. The battery cell according to any one of claims 1-3, characterized in that, The positive electrode film layer includes at least the following lithium replenishing agent and the lithium iron phosphate material: On the longitudinal section along the thickness direction of the positive electrode sheet, the average length of the longest diameter of the lithium replenishing agent is a, and the average length of the longest diameter of the lithium iron phosphate material is b, and both satisfy: 5μm≤ab≤11μm.

5. The battery cell according to claim 4, characterized in that, 1μm≤b≤2μm, 7μm≤a≤12μm.

6. The battery cell according to any one of claims 1-5, characterized in that, The lithium supplement includes a matrix comprising Li x N y O z , Wherein, 1≤x≤6, 1≤y≤6, 2≤z≤12, and N includes one or more of the elements Na, Ni, Co, Mn, Al, and Fe.

7. The battery cell according to any one of claims 1-5, characterized in that, The lithium replenishing agent includes a matrix, which includes one or both of Li2NiO2 and Li5FeO4.

8. The battery cell according to any one of claims 1-5, characterized in that, The lithium supplement includes a matrix comprising Li n NiO m and Li e FeO f One or two of them, wherein 0 < m ≤ 2, 0 ≤ n ≤ 2, 0 ≤ e ≤ 5, and 0 < f ≤ 4.

9. The battery cell according to any one of claims 1-5, characterized in that, The lithium supplement includes a matrix comprising NiO. m and Li p FeO q One or two of them, where 0 < m ≤ 2, 0 ≤ p ≤ 1, and 0 < q ≤ 2.

10. The battery cell according to any one of claims 1-9, characterized in that, The molar content of Li in the lithium replenishing agent is greater than the molar content of Li in the lithium iron phosphate material.

11. The battery cell according to any one of claims 6-9, characterized in that, At least a portion of the surface of the substrate has a coating layer, which includes one or more of the elements C, Al, Zr, P, S, Si, and B.

12. The battery cell according to claim 11, characterized in that, The thickness of the coating layer is 10nm-200nm.

13. The battery cell according to claim 11 or 12, characterized in that, There is a second gap between the substrate and the coating layer, the second gap being 5nm-50nm.

14. The battery cell according to any one of claims 11-13, characterized in that, The matrix includes doping elements, which include one or more of Al, Mn, Ti, Ni, Si, B, S, and P.

15. The battery cell according to claim 14, characterized in that, Based on the total mass of the matrix, the mass percentage of the dopant element is 0.01%-0.2%.

16. The battery cell according to claim 6, characterized in that, N includes the element Fe, and the molar ratio of Fe atoms to O atoms in the lithium replenisher is 1:(2-2.5).

17. The battery cell according to any one of claims 1-16, characterized in that, The positive electrode film layer also includes a conductive agent, which includes one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

18. The battery cell according to any one of claims 1-17, characterized in that, When the battery cell is charged to 4.5V at a rate of 0.05C, gas is generated in the battery cell. The gas includes oxygen, and the mass percentage of oxygen is 30%-80% based on the total mass of the gas.

19. The battery cell according to any one of claims 1-18, characterized in that, Also includes: An electrolyte comprising a solvent, an electrolyte salt, and additives, wherein the molar concentration of the electrolyte salt in the electrolyte is 1.1 mol / L to 1.5 mol / L, the additives include one or more of phosphorus-containing additives, fluorine-containing additives, and sulfur-containing additives, and the solvent includes cyclic carbonates and linear carbonates.

20. A battery device, characterized in that, Includes the battery cell as described in any one of claims 1-19.

21. An electrical appliance, characterized in that, Includes the battery cell according to any one of claims 1-19, the battery cell being used to provide electrical energy.

Images