Battery monomer, battery device and electric equipment

Abstract

The invention provides a battery monomer, a battery device and electric equipment, the battery monomer comprises an electrode assembly and an electrolyte, the electrode assembly comprises a positive pole piece, the positive pole piece comprises a positive current collector and a positive active material layer arranged on at least one side of the positive current collector, and the positive active material layer is arranged on the positive current collector. The size of the positive electrode active material layer along the length direction of the battery monomer is 300mm-950mm; the electrolyte comprises a lithium salt, and based on the total mass of the electrolyte, the mass ratio of the lithium salt is 10%-18%; the lithium salt comprises fluorine-containing sulfimide lithium salt and lithium hexafluorophosphate, based on the total mass of the electrolyte, the ratio of the mass ratio of the fluorine-containing sulfimide lithium salt to the mass ratio of the lithium hexafluorophosphate is 0.4-1, and the viscosity of the electrolyte at normal temperature is 2.3 mPa.s-3. 5 mPa.s.

Description

[0001] This application claims the priority of the PCT international application PCT / CN2025 / 086912, titled "Battery Cell, Battery Device, and Electrical Equipment", filed on April 2, 2025. The entire content of this application is incorporated herein by reference. Technical Field

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

[0003] Batteries are not only applied to energy storage power systems such as hydraulic, thermal, wind, and solar power stations, but also widely used in electric transportation such as electric bicycles, electric motorcycles, and electric vehicles, as well as in multiple fields such as military equipment and aerospace. By increasing the size of the positive active material layer on the positive electrode tab, the energy density of the battery cell can be improved. However, after the size of the positive active material layer increases, the difficulty of electrolyte infiltration increases, which affects the migration of lithium ions on the positive electrode tab and reduces the fast charging performance and cycle life of the battery cell. Summary of the Invention

[0004] In a first aspect of this application, a battery cell is provided. The battery cell includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode tab. Wherein, the positive electrode tab includes a positive current collector and a positive active material layer provided on at least one side of the positive current collector. The size of the positive active material layer along the length direction of the battery cell is 300 mm - 950 mm; the electrolyte includes a lithium salt, and based on the total mass of the electrolyte, the mass percentage of the lithium salt is 10% - 18%; the lithium salt includes lithium fluorosulfonylimide salt and lithium hexafluorophosphate. Based on the total mass of the electrolyte, the ratio of the mass percentage of the lithium fluorosulfonylimide salt to the mass percentage of the lithium hexafluorophosphate is 0.4 - 1, and the viscosity of the electrolyte at room temperature is 2.3 mPa·s - 3.5 mPa·s. Thus, the long electrode tab battery cell has a relatively high energy density. By controlling the viscosity of the electrolyte, the type and content of the lithium salt, the migration rate of lithium ions on the long electrode tab is increased, and the fast charging and cycle life of the battery cell are improved.

[0005] According to some embodiments of this application, the electrolyte includes a first solvent. The viscosity of the first solvent at room temperature is 0.3 mPa·s - 0.6 mPa·s, and based on the total mass of the electrolyte, the mass percentage of the first solvent is 8% - 60%. Thus, a low-viscosity first solvent is used as a co-solvent to reduce the overall viscosity of the electrolyte and increase the migration rate of lithium ions.

[0006] According to some embodiments of the present application, the size of the positive electrode active material layer in the length direction of the battery cell is 400 mm - 950 mm. Thereby, the energy density of the battery cell is increased.

[0007] According to some embodiments of the present application, the size of the positive electrode active material layer in the length direction of the battery cell is 500 mm - 950 mm. Thereby, the energy density of the battery cell is increased.

[0008] According to some embodiments of the present application, the first solvent includes a carboxylic acid ester solvent. Thereby, the conductivity of the electrolyte is increased, and the fast charging performance of the battery cell is improved.

[0009] According to some embodiments of the present application, the carboxylic acid ester solvent includes a compound represented by Formula I: Formula I, wherein R 5 includes any one of a hydrogen atom, a halogen atom, an alkyl group having 1 - 5 carbon atoms, and a halogenated alkyl group having 1 - 5 carbon atoms, and R 6 includes any one of an alkyl group having 1 - 5 carbon atoms and a halogenated alkyl group having 1 - 5 carbon atoms. Thereby, the carboxylic acid ester solvents of the above types have a relatively small molecular weight, which can increase the ionic conductivity of the electrolyte and improve the rate performance of the battery cell.

[0010] According to some embodiments of the present application, the carboxylic acid ester solvent includes one or more of methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, and ethyl butyrate. Thereby, the carboxylic acid ester solvents of the above types have a relatively small molecular weight, which can increase the ionic conductivity of the electrolyte and improve the rate performance of the battery cell.

[0011] According to some embodiments of the present application, based on the total mass of the electrolyte, the mass percentage of the first solvent is 30% - 60%. Thereby, the viscosity of the electrolyte is reduced.

[0012] According to some embodiments of the present application, the lithium fluorosulfonylimide salt includes one or more of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, and lithium perfluorobutanesulfonylimide. Thereby, the migration rate of lithium ions is increased.

[0013] According to some embodiments of the present application, based on the total mass of the electrolyte, the mass percentage of the lithium fluorosulfonylimide salt is 4% - 10%. Thereby, the migration rate of lithium ions and the stability of the electrolyte are improved.

[0014] According to some embodiments of the present application, based on the total mass of the electrolyte, the mass percentage of the lithium fluorosulfonylimide salt is 4% - 8%. Thereby, the migration rate of lithium ions and the stability of the electrolyte are improved.

[0015] According to some embodiments of the present application, based on the total mass of the electrolyte, the mass proportion of lithium hexafluorophosphate is 8% - 12%. Thereby, the migration rate of lithium ions is increased.

[0016] According to some embodiments of the present application, the electrolyte further includes a second solvent, the second solvent includes a carbonate solvent, and the carbonate solvent includes one or more of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate. Thereby, the dielectric constant of the electrolyte is increased.

[0017] According to some embodiments of the present application, based on the total mass of the electrolyte, the mass proportion of the carbonate solvent is 18% - 75%. Thereby, the ionic conductivity of the electrolyte is increased.

[0018] According to some embodiments of the present application, the electrolyte further includes an additive, and the additive includes one or more of a carbonate additive, a sulfur-containing additive, and a lithium salt additive. Thereby, the cycle performance and fast charging performance of the battery cell are improved.

[0019] According to some embodiments of the present application, the carbonate additive includes one or two of vinylene carbonate and ethylene carbonate derivatives. Thereby, the cycle life of the battery cell is increased.

[0020] According to some embodiments of the present application, based on the total mass of the electrolyte, the mass proportion of the carbonate additive is 3% - 8%. Thereby, while increasing the cycle life of the battery cell, the impedance of the battery cell is reduced.

[0021] According to some embodiments of the present application, based on the total mass of the electrolyte, the mass proportion of vinylene carbonate is 2% - 5%. Thereby, a stable SEI film is formed to improve the transport of lithium ions.

[0022] According to some embodiments of the present application, the ethylene carbonate derivative includes a compound represented by Formula II: Formula II, wherein, R 1 , R 2 , R 3 , R 4 each independently includes any one of a hydrogen atom, a halogen atom, an alkyl group having 1 - 5 carbon atoms, and a halogenated alkyl group having 1 - 5 carbon atoms, and R 1 , R 2 , R 3 , R 4 are not simultaneously hydrogen atoms. Thereby, the cycle life of the battery cell is increased.

[0023] According to some embodiments of the present application, based on the total mass of the electrolyte, the mass proportion of the ethylene carbonate derivative is 0% - 4%. Thereby, the uniformity and compactness of the SEI film are improved, and the side reactions between the electrolyte and the negative electrode surface are reduced.

[0024] According to some embodiments of the present application, based on the total mass of the electrolyte, the mass proportion of the ethylene carbonate derivative is 1.5% - 3.5%. Thereby, the uniformity and compactness of the SEI film are improved, and the side reactions between the electrolyte and the negative electrode surface are reduced.

[0025] According to some embodiments of the present application, the sulfur-containing additive includes one or more of vinylene sulfate, divinylene sulfate, 1,3 - propanesultone, butene sulfite, ethylene sulfite, methylene methanedisulfonate. Thereby, the impedance of the battery cell is reduced, and the fast charging performance of the battery cell is improved.

[0026] According to some embodiments of the present application, based on the total mass of the electrolyte, the mass proportion of the sulfur-containing additive is 0 - 2%. Thereby, while reducing the impedance of the battery cell, the gas generation of the battery cell is reduced.

[0027] According to some embodiments of the present application, based on the total mass of the electrolyte, the mass proportion of the sulfur-containing additive is 0.5% - 2%. Thereby, while reducing the impedance of the battery cell, the gas generation of the battery cell is reduced.

[0028] According to some embodiments of the present application, the lithium salt additive includes one or more of lithium difluorophosphate, lithium difluorooxalate borate, lithium tetrafluoroborate, lithium bis(oxalato)borate. Thereby, the gas generation of the battery cell under high temperature conditions is reduced.

[0029] According to some embodiments of the present application, based on the total mass of the electrolyte, the mass proportion of the lithium salt additive is 0 - 1%. Thereby, while reducing the gas generation of the battery cell, the film-forming impedance is reduced.

[0030] According to some embodiments of the present application, based on the total mass of the electrolyte, the mass proportion of the lithium salt additive is 0.2% - 1%. Thereby, while reducing the gas generation of the battery cell, the film-forming impedance is reduced.

[0031] According to some embodiments of the present application, the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material includes a lithium-containing phosphate. Thereby, the cycle life of the battery cell is improved.

[0032] According to some embodiments of the present application, the lithium-containing phosphate includes: a matrix; a first coating material, the first coating material is located on at least part of the surface of the matrix, and the first coating material contains carbon elements. Thereby, the conductivity of the lithium-containing phosphate is improved.

[0033] According to some embodiments of the present application, based on the total mass of the lithium-containing phosphate, the mass percentage of the carbon element is 0.8% - 2.3%. Thereby, while improving the conductivity of the lithium-containing phosphate, the loading of the lithium-containing phosphate on the positive electrode sheet is increased, and the energy density of the battery cell is increased.

[0034] According to some embodiments of the present application, the first coating material includes a compound represented by Formula III: Li 3-d1 Fe 2-d1 M1 d1 (PO m1 ) n1 Formula III, where 0 ≤ d 1 ≤ 1, 3 ≤ m 1 ≤ 5, 2 ≤ n 1 ≤ 4; M1 includes one or more of Ti, Zr, Hf, Ge, and Sn. Thereby, the ionic conductivity and specific capacity of the positive electrode active material are improved, and the fast charging performance and energy density of the battery cell are improved.

[0035] According to some embodiments of the present application, the matrix includes a compound represented by Formula IV: Li x1 A y1 Me a1 M2 b1 P 1-c1 X c1 Y z1 Formula IV, where 0.5 ≤ x 1 ≤ 1.3, 0 ≤ y 1 ≤ 1.3, 0.9 ≤ x 1 + y 1 ≤ 1.3; 0.9 ≤ a 1 ≤ 1.5, 0 ≤ b 1 ≤ 0.5, 0.9 ≤ a 1 + b 1 ≤ 1.5; 0 ≤ c 1 ≤ 0.5; 3 ≤ z 1 ≤ 5; wherein, A includes one or more of Na, K, and Mg; Me includes one or more of Mn, Fe, Co, and Ni; M2 includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; X includes one or more of S, Si, Cl, B, C, N, and P; Y includes one or more of O and F. Thereby, the cycle performance and safety of the battery cell are improved.

[0036] According to some embodiments of the present application, the matrix includes one or more of lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, lithium nickel phosphate, and lithium cobalt phosphate. Thereby, the cycle performance and safety of the battery cell are improved.

[0037] According to some embodiments of the present application, the powder compaction density of the positive electrode active material under 30,000 N is 2.43 g / cm 3 -2.85 g / cm 3 . Thereby, the energy density of the battery cell is improved.

[0038] According to some embodiments of the present application, the single-sided coating weight of the positive electrode active material layer is 200 mg / 1540.25 mm 2 -350 mg / 1540.25 mm 2 . Thereby, the energy density of the battery cell is improved.

[0039] According to some embodiments of the present application, the electrode assembly further includes a negative electrode plate, the negative electrode plate includes a negative electrode current collector and a negative electrode active material layer provided on at least one side of the negative electrode current collector, the negative electrode active material layer includes a negative electrode active material, and the negative electrode active material includes a carbon-based material and / or a silicon-based material. Thereby, the energy density and cycle performance of the battery cell are improved.

[0040] According to some embodiments of the present application, the carbon-based material includes graphite. Thereby, the cycle performance of the battery cell is improved.

[0041] According to some embodiments of the present application, the graphite is secondary particles formed by aggregation of primary particles, and at least part of the surface of the secondary particles has a second coating material, and the second coating material includes amorphous carbon. Thereby, the side reaction between the negative electrode surface and the electrolyte is reduced, and the cycle performance of the battery cell is improved.

[0042] According to some embodiments of the present application, based on the total mass of the graphite, the mass ratio of the second coating material is 2%-5%. Thereby, while improving the cycle performance of the battery cell, the energy density of the battery cell is improved.

[0043] According to some embodiments of the present application, the volume average particle size Dv50 of the graphite is 8.5 μm - 13.8 μm. Thereby, the migration path of lithium ions in the solid phase is shortened, and the fast charging ability of the battery cell is improved; at the same time, the side reaction between graphite and the electrolyte is reduced.

[0044] According to some embodiments of the present application, based on the total mass of the negative electrode active material layer, the mass ratio of silicon element is 0.3%-5% Thereby, the energy density of the battery cell is improved.

[0045] According to some embodiments of the present application, the single-sided coating weight of the negative electrode active material layer is 90 mg / 1540.25 mm 2 -140 mg / 1540.25 mm 2 . Thereby, the energy density of the battery cell is increased.

[0046] According to some embodiments of the present application, along the length direction of the battery cell, the size of the negative electrode active material layer is larger than the size of the positive electrode active material layer, and the difference between the size of the negative electrode active material layer and the size of the positive electrode active material layer is OH 1 ; along the width direction of the battery cell, the size of the negative electrode active material layer is larger than the size of the positive electrode active material layer, and the difference between the size of the negative electrode active material layer and the size of the positive electrode active material layer is OH 2 , where OH 1 is greater than or equal to OH 2 . Thereby, while increasing the energy density of the battery cell, the lithium deposition on the negative electrode is reduced.

[0047] According to some embodiments of the present application, 1 mm ≤ OH 1 ≤ 4 mm, 1 mm ≤ OH 2 ≤ 3 mm. Thereby, while increasing the energy density of the battery cell, the lithium deposition on the negative electrode is reduced.

[0048] According to some embodiments of the present application, a positive electrode tab is provided on the positive electrode plate, and a negative electrode tab is provided on the negative electrode plate. The positive electrode tab extends along the length direction or the width direction of the positive electrode plate; and / or the negative electrode tab extends along the length direction or the width direction of the negative electrode plate. Thereby, the current transmission efficiency is improved, the resistance of the battery cell is reduced, and the rate performance of the battery cell is improved.

[0049] According to some embodiments of the present application, along the length direction of the battery cell, the length of the positive electrode active material layer is greater than 500 mm, and the positive electrode tab extends at both ends or one end in the length direction or the width direction of the positive electrode plate. Thereby, when charging and discharging at a relatively high rate, the current can be dispersed, and the risk of lithium deposition is reduced.

[0050] According to some embodiments of the present application, along the length direction of the battery cell, the length of the positive electrode active material layer is less than or equal to 500 mm, and the positive electrode tab extends at one end or both ends in the length direction or the width direction of the positive electrode plate, or the positive electrode tab extends at both ends or one end in the length direction or the width direction of the positive electrode plate. Thereby, the current guiding ability of the positive electrode plate is improved.

[0051] According to some embodiments of the present application, the electrode assembly further includes a separator, and the porosity of the separator is 20% - 70%. Thereby, the transmission efficiency of lithium ions is improved, and the rate performance of the battery cell is improved.

[0052] According to some embodiments of the present application, the porosity of the separator is 35% - 60%. Thereby, the transmission efficiency of lithium ions is improved, and the rate performance of the battery cell is improved.

[0053] According to some embodiments of the present application, the separator includes: a base film; a first functional layer located on at least one side of the base film, the first functional layer including a first inorganic substance; and a second functional layer located on the side of the first functional layer away from the base film, the second functional layer including a second inorganic substance and a non-fluoropolymer. Thereby, the heat resistance of the separator is improved, and the safety of the battery cell is improved.

[0054] According to some embodiments of the present application, the non-fluoropolymer includes an acrylate copolymer. Thereby, the adhesiveness of the non-fluoropolymer is improved, and the risk of the second functional layer peeling off is reduced.

[0055] According to some embodiments of the present application, the first inorganic substance and the second inorganic substance each independently include one or more of silicon oxide, aluminum oxide, boehmite, barium sulfate, calcium oxide, titanium oxide, zinc oxide, magnesium oxide, zirconium oxide, and tin oxide. Thereby, the heat resistance of the separator is improved, and the safety of the battery cell is improved.

[0056] According to some embodiments of the present application, the thickness of the base film is 4μm - 12μm. Thereby, while reducing the short circuit between the positive and negative electrodes, the volume occupied by the separator in the battery cell is reduced, and the volume energy density of the battery cell is improved.

[0057] According to some embodiments of the present application, the battery cell includes a housing and a cover assembly, the cover assembly is disposed at at least one end of the housing, the housing and the cover assembly define a receiving cavity, the electrode assembly is disposed in the receiving cavity, and the thickness of the housing on the large surface of the battery cell is 0.1mm - 0.5mm. Thereby, the energy density of the battery cell is improved.

[0058] According to some embodiments of the present application, the thickness of the housing on the large surface of the battery cell is 0.2mm - 0.35mm. Thereby, the energy density of the battery cell is improved.

[0059] According to some embodiments of the present application, the cover plate assembly includes a first cover plate assembly and a second cover plate assembly. The first cover plate assembly and the second cover plate assembly are disposed at two ends in the length direction or the width direction of the housing. The first cover plate assembly includes a first cover plate and a first electrode terminal, and the second cover plate assembly includes a second cover plate and a second electrode terminal. The polarities of the first electrode terminal and the second electrode terminal are opposite. Thereby, during charging, the temperature rise of the battery cell is reduced, and further the impedance of the battery cell is reduced.

[0060] According to some embodiments of the present application, the minimum cross-sectional area of the first electrode terminal and / or the second electrode terminal is S, and it satisfies 150 mm 2 ≤ S ≤ 1000 mm 2 . Thereby, the overcurrent capacity of the battery cell is improved.

[0061] According to some embodiments of the present application, the volumetric energy density of the battery cell is 400 Wh / L - 530 Wh / L.

[0062] According to some embodiments of the present application, the charging time of the battery cell from 10% SOC to 80% SOC is 5 min - 15 min.

[0063] The second aspect of the present application provides a battery device, including the battery cell provided in the first aspect of the present application. The battery device is one or more of a battery module, a battery pack, and an energy storage device.

[0064] The third aspect of the present application provides an electrical device, including the battery cell provided in the first aspect of the present application or the battery device provided in the second aspect of the present application. The battery cell or the battery device provides electrical energy for the electrical device.

[0065] The additional aspects and advantages of the present application will be partially given in the following description, partially become apparent from the following description, or be understood through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] By reading the following detailed description of the preferred embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present application. Moreover, in all the drawings, the same reference numerals are used to represent the same components. In the drawings: Figure 1 is a schematic structural diagram of a housing according to an embodiment of the present application.

[0067] Figure 2 is a schematic structural diagram of a positive electrode plate according to an embodiment of the present application.

[0068] Figure 3It is a schematic structural diagram of a positive electrode active material layer and a negative electrode active material layer according to an embodiment of the present application.

[0069] Figure 4 It is a schematic structural diagram of a positive electrode sheet according to an embodiment of the present application.

[0070] Figure 5 It is a schematic structural diagram of a positive electrode sheet according to another embodiment of the present application.

[0071] Figure 6 It is a schematic structural diagram of a positive electrode sheet according to another embodiment of the present application.

[0072] Figure 7 It is a schematic structural diagram of a positive electrode sheet according to another embodiment of the present application.

[0073] Figure 8 It is a schematic structural diagram of a negative electrode sheet according to an embodiment of the present application.

[0074] Figure 9 It is a schematic structural diagram of a negative electrode sheet according to another embodiment of the present application.

[0075] Figure 10 It is a schematic structural diagram of a negative electrode sheet according to another embodiment of the present application.

[0076] Figure 11 It is a schematic structural diagram of a negative electrode sheet according to another embodiment of the present application.

[0077] Figure 12 It is a schematic structural diagram of a separator according to an embodiment of the present application.

[0078] Figure 13 It is a schematic structural diagram of a battery cell according to an embodiment of the present application.

[0079] Figure 14 It is a schematic structural diagram of an electrical device according to an embodiment of the present application.

[0080] Description of reference numerals: 1 Battery cell; 11 Housing; 111 Large-surface housing; 121 Positive electrode sheet; 1210 Positive electrode tab; 1212 Positive electrode active material layer; 122 Negative electrode sheet; 1220 Negative electrode tab; 1222 Negative electrode active material layer; 123 Separator; 1231 Base film; 1232 First functional layer; 1233 Second functional layer. Detailed description of the specific implementation

[0081] The embodiments of the technical solutions of the present application will be described in detail below. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, so they are only examples and cannot be used to limit the protection scope of the present application.

[0082] References to "embodiments" in this specification mean that a particular feature, structure, or characteristic described in connection with the embodiments can be included in at least one embodiment of the present application. The phrase appears in various places in the specification and is not necessarily referring to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0083] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0084] Unless otherwise specified, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0085] Unless otherwise specified, all steps of the present application can be carried out in sequence or randomly, preferably in sequence. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) carried out in sequence, or may also include steps (b) and (a) carried out in sequence. For example, it is mentioned that the method may further include step (c), which means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or may also include steps (a), (c), and (b), or may also include steps (c), (a), and (b), etc.

[0086] Currently, from the perspective of the development of the market situation, the application of batteries is becoming more and more extensive. Batteries are not only applied to energy storage power systems such as hydropower, thermal power, wind power, and solar power stations, but also widely applied to electric transportation means such as electric bicycles, electric motorcycles, and electric vehicles, as well as multiple fields such as military equipment and aerospace. With the continuous expansion of the battery application field, the market demand is also continuously increasing. The battery monomers in the related technologies cannot simultaneously meet the requirements of high energy density, fast charging, and long cycle life.

[0087] In a first aspect of the present application, a battery monomer is provided. The battery monomer includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode tab, wherein, The positive electrode tab includes a positive electrode current collector and a positive electrode active material layer provided on at least one side of the positive electrode current collector. The size of the positive electrode active material layer in the length direction of the battery monomer is 300 mm - 950 mm; The electrolyte includes a lithium salt. Based on the total mass of the electrolyte, the mass proportion of the lithium salt is 10% - 18%; the lithium salt includes lithium fluorosulfonylimide salt and lithium hexafluorophosphate. Based on the total mass of the electrolyte, the ratio of the mass proportion of the lithium fluorosulfonylimide salt to the mass proportion of the lithium hexafluorophosphate is 0.4 - 1, and the viscosity of the electrolyte at room temperature is 2.3 mPa·s - 3.5 mPa·s.

[0088] In this application, with reference to Figure 1 and Figure 2 , the battery cell includes a housing 11. The length direction and width direction of the battery cell are as Figure 1 shown. The positive electrode plate 121 includes a positive electrode current collector 1211 and a positive electrode active material layer 1212 provided on at least one side of the positive electrode current collector 1211. The dimension of the positive electrode active material layer 1212 in the length direction of the battery cell is as shown by L in the figure. The dimension of L can be measured with a ruler.

[0089] As an example, the dimension of the positive electrode active material layer in the length direction of the battery cell can be 300 mm, 500 mm, 700 mm, 900 mm, 950 mm, etc., or can be a range composed of any of the above values.

[0090] In this application, the test of the contents of lithium fluorosulfonylimide salt and lithium hexafluorophosphate can refer to the standard JY / T 020 - 2002 General Rules for Ion Chromatographic Analysis Methods. For example, freshly prepared electrolyte can be taken as a sample, or free electrolyte of a fresh battery can be taken as a sample, or a battery cell that has been fully discharged (discharged to the discharge cut-off voltage so that the charged state of the battery cell is approximately 0% SOC) can be disassembled in reverse, and the free electrolyte obtained from the battery cell is taken as a sample. The ion chromatographic analysis method is used for detection, the inorganic ion chromatogram is tested, the corresponding inorganic substances are compared according to the chromatographic peak positions, and the percentage of the content of the corresponding inorganic ions is calculated according to the peak areas, and then the ratio of the mass proportion of lithium fluorosulfonylimide to the mass proportion of lithium hexafluorophosphate is calculated.

[0091] As an example, based on the total mass of the electrolyte, the mass proportion of the lithium salt can be 10%, 12%, 14%, 16%, 18%, etc., or can be a range composed of any of the above values.

[0092] As an example, the ratio of the mass proportion of the lithium fluorosulfonylimide salt in the electrolyte to the mass proportion of the lithium hexafluorophosphate in the electrolyte can be 0.4, 0.6, 0.8, 1, etc., or can be a range composed of any of the above values.

[0093] In this application, the viscosity of the electrolyte at room temperature is determined by the rotational viscometer method provided in the national standard GB / T 10247-2008 "Viscosity Measurement Method". Specifically, a certain mass of electrolyte sample is placed in a sample container and placed in a hydrothermal bath for constant temperature and static standing for 10-20 minutes. After the sample temperature is the same as the hydrothermal temperature, a rotational viscometer with the instrument model DV2TLV produced by Brookfield Company is used for testing. When the 18th rotor rotates continuously at a constant speed of 70 r in the sample, the shear force generates a torque on the spring. The torque is proportional to the viscosity, and the viscosity value is obtained. Five samples are tested, and the viscosity is the average value of the five samples. The test equipment meets the following test environmental conditions: 1. External environment of the equipment: temperature is 15-28 °C, humidity is RH < 80%; 2. Internal environment of the equipment: 2 / 3 of the sample container is immersed in a water bath, the medium is water, and the water is used to keep the sample at a constant temperature. The hydrothermal temperature is 25 °C ± 3 °C.

[0094] As an example, the viscosity of the electrolyte at room temperature can be 2.3 mPa·s, 2.5 mPa·s, 2.7 mPa·s, 2.9 mPa·s, 3.1 mPa·s, 3.3 mPa·s, 3.5 mPa·s, etc., or can be a range composed of any of the above values.

[0095] For the battery cell proposed in this application, the energy density of the battery cell is increased by extending the length of the positive electrode active material layer. After the length of the positive electrode plate increases, in the length direction of the battery cell, it is difficult for the electrolyte to infiltrate, which affects the fast charging and cycle life of the battery cell. Therefore, in this application, by controlling the viscosity of the electrolyte, the infiltration effect of the electrolyte on the long electrode plate is improved. However, for the long electrode plate, the electron and ion transmission paths are longer on the side far from the tab, and the transmission impedance is larger, reducing the fast charging performance of the battery cell. In response to this, a lithium fluorosulfonylimide salt with a large lithium ion transference number is added to the electrolyte. The sufficient infiltration of the electrolyte provides a continuous channel for the transmission of lithium ions. On the basis of the unobstructed channel, using a lithium salt with a large ion transference number can further improve the migration rate of lithium ions. In this application, further by controlling the contents of the lithium fluorosulfonylimide salt and lithium hexafluorophosphate, the viscosity of the electrolyte is reduced, so that both the viscosity of the electrolyte and the lithium ion migration rate are maintained within a suitable range to meet the requirements of the long electrode plate battery cell for fast charging and cycle life.

[0096] According to some embodiments of the present application, based on the total mass of the electrolyte, the mass ratio of the lithium fluorosulfonylimide salt is 4%-10%. For example, it can be 4%, 6%, 8%, 10%, etc., or can be a range composed of any of the above values. Thereby, the migration rate of lithium ions is increased. According to some embodiments of the present application, based on the total mass of the electrolyte, the mass ratio of the lithium fluorosulfonylimide salt is 4%-8%.

[0097] According to some embodiments of the present application, based on the total mass of the electrolyte, the mass proportion of lithium hexafluorophosphate is 8% - 12%. For example, it can be 8%, 9%, 10%, 11%, 12%, etc., or it can be a range composed of any of the above values. Thereby, the migration rate of lithium ions and the stability of the electrolyte are improved, and the viscosity of the electrolyte is reduced.

[0098] Thereby, a battery cell with both high energy density, excellent fast charging performance and cycle life is obtained.

[0099] According to some specific embodiments of the present application, the size of the positive electrode active material layer along the length direction of the battery cell is 400 mm - 950 mm.

[0100] According to some specific embodiments of the present application, the size of the positive electrode active material layer along the length direction of the battery cell is 500 mm - 950 mm.

[0101] According to some embodiments of the present application, the electrolyte includes a first solvent, the viscosity of the first solvent at room temperature is 0.3 mPa·s - 0.6 mPa·s, and based on the total mass of the electrolyte, the mass proportion of the first solvent is 8% - 60%. That is to say, the type of the first solvent is not particularly limited as long as the viscosity at room temperature is within the above range. Thereby, a low-viscosity first solvent is used as a co-solvent to reduce the overall viscosity of the electrolyte and improve the migration rate of lithium ions.

[0102] Non-limitingly, referring to GB / T 9722 - 2023 General Rules for Chemical Reagents - Gas Chromatography, qualitative and quantitative analysis of the solvents in the electrolyte is carried out by gas chromatography, and whether the solvent includes the first solvent with a viscosity of 0.3 mPa·s - 0.6 mPa·s under room temperature conditions is judged through the types of solvents measured. For example: an unformed lithium-ion battery can be disassembled, or a fresh battery after formation and without charge-discharge cycles can be used to determine the types of organic solvents in the electrolyte of the lithium-ion battery by gas chromatography, and the same organic solvents are used to replace the organic solvents in the electrolyte for viscosity testing. Specifically, the test method for measuring the viscosity of the electrolyte at 25 °C described above can be referred to. For example: the viscosity of ethyl acetate (EA) at room temperature is about 0.45 mPa·s, the viscosity of methyl formate at room temperature is about 0.33 mPa·s, and the viscosity of methyl acetate at room temperature is about 0.40 mPa·s.

[0103] As an example, the viscosity of the first solvent at room temperature can be 0.3 mPa·s, 0.4 mPa·s, 0.45 mPa·s, 0.5 mPa·s, 0.55 mPa·s, 0.6 mPa·s, etc., or it can be a range composed of any of the above values.

[0104] As an example, the mass percentage of the first solvent may be 8%, 10%, 20%, 30%, 40%, 50%, 60%, etc., or may be a range composed of any of the above values.

[0105] According to some embodiments of the present application, the first solvent may include a carboxylic acid ester solvent. Thereby, the conductivity of the electrolyte is improved, and the fast charging performance of the battery cell is improved.

[0106] According to some embodiments of the present application, the carboxylic acid ester solvent includes a compound represented by Formula I: Formula I wherein, R 5 includes any one of a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, and a halogenated alkyl group having 1 to 5 carbon atoms, and R 6 includes any one of an alkyl group having 1 to 5 carbon atoms and a halogenated alkyl group having 1 to 5 carbon atoms. Thereby, the carboxylic acid ester solvents of the above types have a relatively small molecular weight, which can improve the ionic conductivity of the electrolyte and the rate performance of the battery cell.

[0107] As an example, the carboxylic acid ester solvent includes one or more of methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, and ethyl butyrate. Thereby, the carboxylic acid ester solvents of the above types have a relatively small molecular weight, which can improve the ionic conductivity of the electrolyte and the rate performance of the battery cell.

[0108] According to some embodiments of the present application, based on the total mass of the electrolyte, the mass percentage of the first solvent is 30% - 60%. For example, it may be 30%, 40%, 50%, 60%, etc., or may be a range composed of any of the above values. Thereby, the viscosity of the electrolyte is reduced. When the first solvent is a carboxylic acid ester solvent, by making the content of the carboxylic acid ester solvent within the above range, on the one hand, the viscosity of the electrolyte can be reduced, the internal resistance of the battery cell can be reduced, the migration rate of lithium ions can be increased, and the fast charging performance of the battery cell can be improved; on the other hand, the risk of gas generation of the electrolyte under high temperature conditions can be reduced, and the high temperature cycle life of the battery cell can be improved, thereby obtaining a battery cell with both excellent fast charging performance and high temperature cycle life.

[0109] According to some embodiments of the present application, the electrolyte further includes a second solvent, the second solvent includes a carbonate solvent, and the carbonate solvent includes one or more of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. Thereby, the dielectric constant of the electrolyte is improved.

[0110] According to some embodiments of the present application, based on the total mass of the electrolyte, the mass proportion of the carbonate solvent may be 18% - 75%. For example, it may be 18%, 20%, 30%, 40%, 50%, 60%, 70%, 75%, etc., or may be a range composed of any of the above values. Thereby, the ionic conductivity of the electrolyte is improved.

[0111] According to some embodiments of the present application, the electrolyte further includes additives, and the additives include one or more of carbonate additives, sulfur-containing additives, and lithium salt additives. Thereby, the cycle performance and fast charging performance of the battery cell are improved.

[0112] Additives refer to components with relatively low content in the electrolyte, generally with a mass proportion in the electrolyte not exceeding 10%, and have the characteristics of strong pertinence and small dosage. Without changing the production process, they can significantly optimize a certain aspect of the battery performance.

[0113] In the present application, after disassembling the battery cell to obtain the electrolyte, reference can be made to GB / T9722 - 2023 "General Rules for Chemical Reagents - Gas Chromatography" to qualitatively and quantitatively analyze the additives in the electrolyte by gas chromatography.

[0114] According to some embodiments of the present application, based on the total mass of the electrolyte, the mass proportion of the carbonate additive is 3% - 8%. For example, it may be 3%, 4%, 5%, 6%, 7%, 8%, etc., or may be a range composed of any of the above values. Thereby, while improving the cycle life of the battery cell, the viscosity of the electrolyte is reduced, and the internal resistance of the battery cell is reduced.

[0115] According to some embodiments of the present application, the carbonate additive includes one or two of vinylene carbonate and ethylene carbonate derivatives. Thereby, the carbonate additives of the above types can form a stable interfacial film on the electrode surface, reduce the side reaction between the electrolyte and the electrode surface, and improve the cycle life of the battery cell.

[0116] According to some embodiments of the present application, the mass proportion of the vinylene carbonate is 2% - 5%. For example, it may be 2%, 3%, 4%, 5%, etc., or may be a range composed of any of the above values. Thereby, the reaction activity of vinylene carbonate is relatively high, and a uniform and dense SEI film can be formed on the negative electrode surface during the first charge and discharge process of the battery, improving the stability of the SEI film. Moreover, the SEI film formed by vinylene carbonate (abbreviation: VC) has good ionic conductivity, which can enable lithium ions to be rapidly transmitted between the electrode and the electrolyte, improving the charge and discharge efficiency of the battery.

[0117] According to some embodiments of the present application, the ethylene carbonate derivative includes the compound shown in Formula II: Formula II wherein R 1 , R 2 , R 3 , R 4 each independently includes any one of a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, and a halogenated alkyl group having 1 to 5 carbon atoms, and R 1 , R 2 , R 3 , R 4 are not simultaneously hydrogen atoms. Thereby, the cycle life of the battery cell is improved.

[0118] According to some embodiments of the present application, the mass percentage of the ethylene carbonate derivative is 0-4%. For example, it can be 0.5%, 1%, 2%, 3%, 4%, etc., or can be a range composed of any of the above values. According to some specific embodiments of the present application, the mass percentage of the ethylene carbonate derivative is 1.5%-3.5%. Thereby, the interfacial resistance of the SEI film is reduced, the charge and discharge efficiency of the battery is improved, and when used in combination with VC, the stability and integrity of the SEI film can also be enhanced.

[0119] It should be noted that as the battery cell is charged and discharged, when the addition amount of the ethylene carbonate derivative is small, after disassembling the battery cell to obtain the electrolyte and testing the content of the ethylene carbonate derivative by gas chromatography, the content may be 0.

[0120] According to some embodiments of the present application, the sulfur-containing additive includes one or more of vinylene sulfate, bis(vinylsulfate), 1,3-propane sultone, butene sulfite, ethylene sulfite, and methylene methanedisulfonate. Thereby, additives of the above types can form an SEI film with high ionic conductivity on the surface of the negative electrode, reduce the resistance of lithium ion transmission at the electrode-electrolyte interface, reduce the impedance of the battery cell, and improve the fast charging performance of the battery cell.

[0121] According to some embodiments of the present application, based on the total mass of the electrolyte, the mass percentage of the sulfur-containing additive is 0-2%. For example, it can be 0.5%, 1%, 1.5%, 2%, etc., or can be a range composed of any of the above values. Thereby, while reducing the impedance of the battery cell, the risk of oxidation of the battery cell at a high potential to generate sulfur-containing free radicals is reduced, thereby reducing the decomposition of the solvent caused by the sulfur-containing free radicals and reducing the gas generation of the battery cell. According to some embodiments of the present application, the mass percentage of the sulfur-containing additive can be 0.5%-2%.

[0122] According to some embodiments of the present application, the lithium salt additives include one or more of lithium difluorophosphate, lithium difluorooxalate borate, lithium tetrafluoroborate, and lithium bis(oxalate) borate. Thus, the lithium salt additives of the above types can form a stable SEI film on the surface of the negative electrode, reduce the side reactions between the electrolyte and the electrode surface, reduce the decomposition of the electrolyte, and reduce the gas generation of the battery cell under high-temperature conditions.

[0123] According to some embodiments of the present application, based on the total mass of the electrolyte, the mass percentage of the lithium salt additives is 0-1%. For example, it can be 0.2%, 0.4%, 0.6%, 0.8%, 1%, etc., or it can be a range composed of any of the above values. Thus, while reducing the gas generation of the battery cell, the content of inorganic components in the SEI film is reduced, and the film-forming impedance is reduced. According to some embodiments of the present application, the mass percentage of the lithium salt additives can be 0.2%-1%.

[0124] It should be noted that since the additives in the electrolyte will be consumed to some extent during the formation and charge-discharge cycling processes to generate the relevant components in the SEI film and / or CEI film, when the content of the sulfur-containing additives and the lithium salt additives is tested by gas chromatography after disassembling the battery cell to obtain the electrolyte, the content may be 0.

[0125] Specifically, taking the case where the mass content of the sulfur-containing additive is 0 as an example, it may be that the sulfur-containing additive is not added to the freshly prepared electrolyte, or the electrolyte obtained after disassembling the battery cell does not contain the sulfur-containing additive. This situation may be that the freshly prepared electrolyte does not add the sulfur-containing additive, or a small amount of the sulfur-containing additive is added, but it participates in the film-forming reaction of the SEI film during the formation process of the battery cell, resulting in a mass content of 0 for the sulfur-containing additive during the detection process. Optionally, the freshly prepared electrolyte includes the sulfur-containing additive.

[0126] Furthermore, for adding certain substances, such as additives, to the electrolyte, due to the characteristic that the additives play a role by participating in the film formation on the surface of the active material, the content of the additives in the electrolyte of the battery cell is related to the formation, different battery life cycles, or different battery storage states. Therefore, there may be a difference in the content of the additives between the freshly prepared electrolyte and the electrolyte obtained by reverse-disassembling the battery cell. However, those skilled in the art can know the approximate range of the content of the relevant substances in the corresponding freshly prepared electrolyte according to the performance expression level (such as the number of cycling times), residual content, etc. of the battery cell. Similarly, those skilled in the art can also know the approximate range of the content of the non-freshly prepared (i.e., reverse) electrolyte corresponding to the freshly prepared additive content according to the performance requirements and storage environment of the battery cell.

[0127] Therefore, the additive content mentioned in the technical solution of the present application can be the content of the additive actively added to the fresh electrolyte, or the content of the residual additive detected reversely according to the actual battery state.

[0128] According to some embodiments of the present application, the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material includes a lithium-containing phosphate. Thereby, the cycle life of the battery cell is improved.

[0129] According to some embodiments of the present application, the lithium-containing phosphate includes: a matrix; a first coating material located on at least a part of the surface of the matrix, and the first coating material contains carbon elements. Thereby, a good conductive network is formed between the lithium-containing phosphate particles, and the electronic conductivity of the lithium-containing phosphate is improved.

[0130] According to some embodiments of the present application, based on the total mass of the lithium-containing phosphate, the mass ratio of the carbon element is 0.8% - 2.3%. For example, it can be 0.8%, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.3%, etc., or it can be a range composed of any of the above values. Thereby, while improving the electronic conductivity of the lithium-containing phosphate, the influence on lithium ion transmission is reduced, the loading of the lithium-containing phosphate on the positive electrode sheet is increased, and the energy density of the battery cell is improved.

[0131] According to some embodiments of the present application, the first coating material includes a compound shown in Formula III: Li 3-d1 Fe 2-d1 M1 d1 (PO m1 ) n1 Formula III, wherein, 0 ≤ d 1 ≤ 1, 3 ≤ m 1 ≤ 5, 2 ≤ n 1 ≤ 4; M1 includes one or more of Ti, Zr, Hf, Ge, and Sn.

[0132] The compound shown in Formula III has excellent ionic conductivity, and together with the carbon element with excellent conductivity in the first coating material, it improves the conductivity and ionic conductivity of the lithium-containing phosphate, which is beneficial to improving the fast charging performance of the battery.

[0133] According to some embodiments of the present application, the matrix includes a compound shown in Formula IV: Li x1 A y1 Me a1 M2 b1 P 1-c1 X c1 Y z1 Formula IV, wherein, 0.5 ≤ x 1 ≤ 1.3, 0 ≤ y 1 ≤ 1.3, 0.9 ≤ x 1 + y 1 ≤ 1.3; 0.9 ≤ a 1 ≤ 1.5, 0 ≤ b 1 ≤ 0.5, 0.9 ≤ a 1 + b 1 ≤ 1.5; 0 ≤ c 1 ≤ 0.5; 3 ≤ z 1 ≤ 5; wherein, A includes one or more of Na, K, and Mg; Me includes one or more of Mn, Fe, Co, and Ni; M2 includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; X includes one or more of S, Si, Cl, B, C, N, and P; Y includes one or more of O and F. Thus, the cycle performance and safety of the battery cell are improved.

[0134] As an example, x 1 can be 0.5, 0.7, 0.9, 1.1, 1.3, etc., or can be a range composed of any of the above values.

[0135] It should be noted that since the lithium ions will be consumed during the processes such as formation and cycling of the battery cell, there will be a situation where the content x of lithium element in the positive active material measured is 1 less than 1. At the same time, if a lithium supplement agent is used in the positive electrode plate and the negative electrode plate, after the battery undergoes processes such as formation and cycling, there will be a situation where the content x of lithium element in the positive active material measured is 1 greater than 1.

[0136] As an example, y 1 can be 0, 0.3, 0.6, 0.9, 1.3, etc., or can be a range composed of any of the above values.

[0137] As an example, a 1 can be 0.9, 1.1, 1.3, 1.5, etc., or can be a range composed of any of the above values.

[0138] As an example, b 1 can be 0, 0.2, 0.4, 0.5, etc., or can be a range composed of any of the above values.

[0139] As an example, c 1 can be 0, 0.2, 0.4, 0.5, etc., or can be a range composed of any of the above values.

[0140] As an example, z 1 can be 3, 4, 5, etc., or can be a range composed of any of the above numerical values.

[0141] According to some embodiments of the present application, the matrix includes one or more of lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, lithium nickel phosphate, and lithium cobalt phosphate. Thereby, the cycling performance and safety of the battery cell are improved.

[0142] According to some embodiments of the present application, the powder compaction density of the positive electrode active material under 30000N can be 2.43 g / cm 3 -2.85 g / cm 3 . For example, it can be 2.43 g / cm 3 , 2.5 g / cm 3 , 2.6 g / cm 3 , 2.7 g / cm 3 , 2.8 g / cm 3 , 2.85 g / cm 3 etc., or can be a range composed of any of the above numerical values. Thereby, the energy density of the battery cell is improved.

[0143] In the present application, the powder compaction density of the material has the meaning well-known in the art, and can be detected by methods and equipment well-known in the art. For example, it can be detected according to the test standard GB / T24533-2019. Specifically, a certain amount of positive electrode active material is taken as a sample and added to a mold with a bottom area of 1.327 cm 2 in a UTM7305 type electronic pressure testing machine, pressurized to 3000 kg (equivalent to 30000 N), kept under pressure for 30 s, then depressurized, kept for 10 s, and then the powder compaction density of the positive electrode active material under the action of 30000 N is recorded and calculated.

[0144] According to some embodiments of the present application, the single-sided coating weight of the positive electrode active material layer can be 200 mg / 1540.25 mm 2 -350 mg / 1540.25 mm 2 . For example, it can be 200 mg / 1540.25 mm 2 , 250 mg / 1540.25 mm 2 , 300 mg / 1540.25 mm 2 , 350 mg / 1540.25 mm 2 etc., or can be a range composed of any of the above numerical values. Thereby, the energy density of the battery cell is improved.

[0145] The present application provides a method for testing the coating weight of a positive electrode active material layer: disassemble the positive electrode sheet from a battery cell. For example, take a positive electrode sheet with single-sided coating (if it is a double-sided coated sheet, the positive electrode active material layer on one side can be wiped off first), and punch it into small round pieces with an area of S 1 and weigh them, record it as M 1 . Then wipe off the positive electrode active material layer of the above-mentioned weighed positive electrode sheet, weigh the weight of the positive electrode current collector, and record it as M 0 . The single-sided coating weight of the positive electrode active material layer = (M 1 - M 0 ) / S 1 .

[0146] According to some embodiments of the present application, the electrode assembly further includes a negative electrode sheet. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer provided on at least one side of the negative electrode current collector. The negative electrode active material layer includes a negative electrode active material, and the negative electrode active material includes a carbon-based material and / or a silicon-based material. Thereby, the energy density and cycle performance of the battery cell are improved.

[0147] According to some embodiments of the present application, the carbon-based material includes graphite. Thereby, the cycle performance of the battery cell is improved.

[0148] According to some embodiments of the present application, the graphite is secondary particles formed by aggregation of primary particles, and at least part of the surface of the secondary particles has a second coating material.

[0149] Secondary particles refer to particles formed by aggregation of two or more primary particles.

[0150] In this article, amorphous carbon refers to a transitional carbon material with a very low degree of graphitization crystallization, approximately an amorphous form (or a structure without a fixed shape and periodic structural rules). In the present application, amorphous carbon refers to the product after carbonization treatment of an organic carbon source, which has more end faces and defects and more lithium ion sites.

[0151] The secondary particles can improve the migration rate of lithium ions, improve the transmission performance of lithium ions, are beneficial to the insertion and extraction of lithium ions, are beneficial to improving the ionic conductivity of the material. The second coating material includes amorphous carbon, which can improve the conductivity of the composite graphite particles. The secondary particles in the core and the coating layer of amorphous carbon jointly improve the electronic conduction performance and ionic conduction performance of the material, and contribute to improving the fast charging performance of the battery cell.

[0152] According to some embodiments of the present application, based on the total mass of the graphite, the mass proportion of the second coating material is 2% - 5%. For example, it can be 2%, 3%, 4%, 5%, etc., or it can be a range composed of any of the above values. Controlling the mass content of the second coating material within a suitable range can improve the conductivity of the material and the fast charging performance of the battery.

[0153] According to some embodiments of the present application, the volume average particle size Dv50 of the graphite can be 8.5μm - 13.8μm. For example, it can be 8.5μm, 9.5μm, 10.5μm, 11.5μm, 12.5μm, 13.8μm, etc., or it can be a range composed of any of the above values. Thus, the volume average particle size of the graphite is relatively small, which can shorten the solid-phase migration path of lithium ions and improve the fast charging ability of the battery cell. At the same time, by making the volume average particle size within the above range, the side reaction between the graphite negative electrode and the electrolyte can also be reduced.

[0154] In the present application, Dv50 refers to the particle size corresponding to when the cumulative volume distribution percentage reaches 50%. For example, referring to the standard GB / T 19077 - 2016 / ISO 13320:2009, it is measured using a laser particle size analyzer (Malvern MasterSize 2000). The specific test process is as follows: Discharge the battery cell to 0% SOC, then disassemble it to take the negative electrode plate, scrape a certain amount of powder on the electrode plate with a blade, then use deionized water to wash it repeatedly by shaking 5 - 10 times. After drying, sinter it in a tube furnace at 400°C for 2h. After sintering, take an appropriate amount of the sample to be measured (the sample concentration should ensure a light transmittance of 8% - 12%), add deionized water, and at the same time perform ultrasonic dispersion to ensure that the sample is completely dispersed. Then, measure the sample according to the standard GB / T19077 - 2016 / ISO 13320:2009.

[0155] According to some embodiments of the present application, based on the total mass of the negative electrode active material layer, the mass proportion of silicon element can be 0.3% - 5%. For example, it can be 0.3%, 1%, 3%, 5%, etc., or it can be a range composed of any of the above values. Thereby, the energy density of the battery cell is improved.

[0156] The mass content of silicon element in the negative electrode active material layer has the meaning well-known in the art and can be detected by using the equipment and methods well-known in the art. For example, the negative electrode sheet is placed in a solvent such as water for soaking to separate the negative electrode active material from the negative electrode current collector, and each substance in the negative electrode film layer is obtained by suction filtration and used as a test sample. The test sample is analyzed by using an inductively coupled plasma - emission spectrometer of model ICAP7400 produced by Thermo Fisher Scientific Company of the United States with reference to the standard of GB / T30902 - 2014, and the silicon element content can be obtained.

[0157] According to some embodiments of the present application, the single - side coating weight of the negative electrode active material layer can be 90mg / 1540.25mm 2 -140mg / 1540.25mm 2 . For example, it can be 90mg / 1540.25mm 2 、110mg / 1540.25mm 2 、125mg / 1540.25mm 2 、140mg / 1540.25mm 2 etc., thereby improving the energy density of the battery cell.

[0158] The present application provides a method for testing the coating weight of the negative electrode active material layer: the negative electrode sheet is disassembled from the battery cell. For example, a single - side coated negative electrode sheet is taken (if it is a double - side coated sheet, the negative electrode active material layer on one side can be wiped off first), and it is punched into small round pieces with an area of S 2 , and its weight is weighed and recorded as M 3 . Then, the negative electrode active material layer of the above - weighed negative electrode sheet is wiped off, and the weight of the negative electrode current collector is weighed and recorded as M 2 . The single - side coating weight of the negative electrode active material layer = (M 3 - M 2 ) / S 2 .

[0159] According to some embodiments of the present application, along the length direction of the battery cell, the size of the negative electrode active material layer is larger than the size of the positive electrode active material layer, and the difference between the size of the negative electrode active material layer and the size of the positive electrode active material layer is OH 1 ; along the width direction of the battery cell, the size of the negative electrode active material layer is larger than the size of the positive electrode active material layer, and the difference between the size of the negative electrode active material layer and the size of the positive electrode active material layer is OH 2 , where OH 1 is greater than or equal to OH 2 .

[0160] During fast charging, the current flowing through the electrode tab side of the electrode is large, the temperature is higher, the migration rate of lithium ions is faster than that of other parts, and lithium deposition is likely to occur. By making the size of the negative electrode active material layer larger than that of the positive electrode active material layer, more negative electrode active material layers can receive lithium ions, improving lithium deposition. And because the lithium ion diffusion path is longer in the length direction of the battery cell, by making OH 1 greater than or equal to OH 2 , more negative electrode active material layers can receive lithium ions in the length direction, reducing the risk of lithium deposition at the edge.

[0161] Specifically, referring to Figure 3 , along the length direction of the battery cell, the size of the positive electrode active material layer is OH 11 , the size of the negative electrode active material layer is OH 21 , and the difference between the size of the negative electrode active material layer and the size of the positive electrode active material layer is OH 1 =OH 21 -OH 11 .

[0162] Referring to Figure 3 , along the width direction of the battery cell, the size of the positive electrode active material layer is OH 12 , the size of the negative electrode active material layer is OH 22 , and the difference between the size of the negative electrode active material layer and the size of the positive electrode active material layer is OH 2 =OH 22 -OH 12 .

[0163] Thus, while increasing the energy density of the battery cell, lithium deposition on the negative electrode is reduced.

[0164] In the present application, the sizes of the positive electrode active material layer and the negative electrode active material layer can be measured with a ruler.

[0165] According to some embodiments of the present application, 1 mm ≤ OH 1 ≤ 4 mm. For example, it can be 1 mm, 2 mm, 3 mm, 4 mm, etc., or it can be a range composed of any of the above values.

[0166] According to some embodiments of the present application, 1 mm ≤ OH 2 ≤ 3 mm. For example, it can be 1 mm, 2 mm, 3 mm, etc., or it can be a range composed of any of the above values. Thus, while increasing the energy density of the battery cell, lithium deposition on the negative electrode is reduced.

[0167] According to some embodiments of the present application, a positive electrode tab is provided on the positive electrode plate, a negative electrode tab is provided on the negative electrode plate, and the positive electrode tab extends out along the length direction or the width direction of the positive electrode plate.

[0168] According to some embodiments of the present application, the negative electrode tab extends out along the length direction or the width direction of the negative electrode plate.

[0169] Thereby, the current transmission efficiency is improved, the resistance of the battery cell is reduced, and the rate performance of the battery cell is improved.

[0170] Reference Figure 4 , only one positive electrode tab 1210 extends out along the length direction of the positive electrode plate 121, reference Figure 5 , positive electrode tabs 1210 extend out at both ends along the length direction of the positive electrode plate 121.

[0171] Reference Figure 6 , only one positive electrode tab 1210 extends out along the width direction of the positive electrode plate 121, reference Figure 7 , positive electrode tabs 1210 extend out at both ends along the width direction of the positive electrode plate 121.

[0172] Reference Figure 8 , only one negative electrode tab 1220 extends out along the length direction of the negative electrode plate 122, reference Figure 9 , negative electrode tabs 1220 extend out at both ends along the length direction of the negative electrode plate 122.

[0173] Reference Figure 10 , only one negative electrode tab 1220 extends out along the width direction of the negative electrode plate 122, reference Figure 11 , negative electrode tabs 1220 extend out at both ends along the width direction of the negative electrode plate 122.

[0174] According to some embodiments of the present application, along the length direction of the battery cell, the length of the positive electrode active material layer is greater than 500 mm, and the positive electrode tab extends out at both ends or at both ends in the width direction of the positive electrode plate. Thereby, when charging and discharging at a relatively high rate, the current can be dispersed and the risk of lithium plating can be reduced.

[0175] According to some embodiments of the present application, along the length direction of the battery cell, the length of the positive electrode active material layer is less than or equal to 500 mm, the positive electrode tab extends out at one end in the length direction or at one end in the width direction of the positive electrode plate, or the positive electrode tab extends out at both ends or at both ends in the width direction of the positive electrode plate. Thereby, the current guiding ability of the positive electrode plate is improved.

[0176] According to some embodiments of the present application, the electrode assembly further comprises a separator, and the porosity of the separator is 20%-70%. For example, it can be 20%, 30%, 40%, 50%, 60%, 70%, etc., or can be a range composed of any of the above values. Thus, the transmission efficiency of lithium ions is improved and the rate performance of the battery cell is improved. According to some embodiments of the present application, the porosity of the separator is 35%-60%.

[0177] In this application, porosity refers to the percentage of the pore volume in the separator to the total volume of the separator. The porosity can be tested in accordance with the standard GB / T 36363-2018 "Polyolefin separator for battery monomers". It should be noted that the actual test process can be slightly different from the standard test process to obtain a more accurate test value based on the differences in test instruments, test errors, and in order to eliminate the test effects on porosity as much as possible.

[0178] According to some embodiments of the present application, reference Figure 12 The isolation film 123 includes: a base film 1231; a first functional layer 1232 located on at least one side of the base film 1231, the first functional layer 1232 including a first inorganic substance; and a second functional layer 1233 located on a side of the first functional layer 1232 away from the base film 1231, the second functional layer 1233 including a second inorganic substance and a non-fluorinated polymer. Thus, the heat resistance of the isolation film is improved, and the safety of the battery cell is improved.

[0179] According to some embodiments of the present application, the non-fluorine polymer includes an acrylic copolymer, thereby improving the adhesion of the non-fluorine polymer and reducing the risk of the second functional layer falling off.

[0180] According to some embodiments of the present application, the first inorganic substance and the second inorganic substance independently include one or more of silicon oxide, aluminum oxide, boehmite, barium sulfate, calcium oxide, titanium oxide, zinc oxide, magnesium oxide, zirconium oxide, and tin oxide, thereby improving the heat resistance of the isolation membrane and the safety of the battery cell.

[0181] According to some embodiments of the present application, the thickness of the base film is 4μm-12μm. For example, it can be 4μm, 6μm, 8μm, 10μm, 12μm, etc., or it can be a range composed of any of the above values. Thus, while reducing the short circuit of the positive and negative electrodes, the volume occupied by the isolation film in the battery cell is reduced, and the energy density of the battery cell is increased. According to some embodiments of the present application, the thickness of the base film is 5μm-9μm.

[0182] In the present application, the thickness of the base film can be tested by a micrometer.

[0183] According to some embodiments of the present application, the battery cell includes a housing and a cover plate assembly. The cover plate assembly is disposed at at least one end of the housing. The housing and the cover plate assembly define a receiving cavity, and the electrode assembly is disposed in the receiving cavity. Refer to Figure 1 , the battery cell includes a housing 11, and the thickness of the housing 111 on the large surface of the battery cell is 0.1 mm - 0.5 mm. Thereby, the energy density of the battery cell is increased.

[0184] According to some embodiments of the present application, the thickness of the housing 111 on the large surface of the battery cell is 0.2 mm - 0.35 mm. Thereby, the energy density of the battery cell is increased.

[0185] According to some embodiments of the present application, the cover plate assembly includes a first cover plate assembly and a second cover plate assembly. The first cover plate assembly and the second cover plate assembly are disposed at two ends of the housing in the length direction or the width direction. The first cover plate assembly includes a first cover plate and a first electrode terminal, and the second cover plate assembly includes a second cover plate and a second electrode terminal. The polarities of the first electrode terminal and the second electrode terminal are opposite. Thereby, during charging, the temperature rise of the battery cell is reduced, and further the impedance of the battery cell is reduced.

[0186] According to some embodiments of the present application, refer to Figure 13 , the battery cell 1 includes a first cover plate assembly and a second cover plate assembly. The first cover plate assembly includes a first cover plate, a first electrode terminal 131, and a third electrode terminal 133. The polarities of the first electrode terminal 131 and the third electrode terminal 133 are opposite. The second cover plate assembly includes a second cover plate, a second electrode terminal 132, and a fourth electrode terminal 134. The polarities of the second electrode terminal 132 and the fourth electrode terminal 134 are opposite.

[0187] According to some embodiments of the present application, the minimum cross-sectional area of the first electrode terminal and / or the second electrode terminal is S, and it satisfies 150 mm 2 ≤ S ≤ 1000 mm 2 . Thereby, the overcurrent capacity of the battery cell is increased, the heat generation of the electrode terminal is reduced, the internal resistance of the battery cell is reduced, and the cycle performance of the battery cell is improved.

[0188] In the present application, the minimum cross-sectional area of the first electrode terminal refers to the minimum cross-sectional area of the first electrode terminal along the direction perpendicular to the current flowing direction, and the minimum cross-sectional area of the second electrode terminal refers to the minimum cross-sectional area of the second electrode terminal along the direction perpendicular to the current flowing direction.

[0189] In this application, when testing the minimum cross-sectional area of the first electrode terminal and / or the second electrode terminal, the calculation can be performed according to the shape of the minimum cross-section and its area calculation formula. For example, if the minimum cross-section of the electrode terminal is circular, the minimum cross-sectional area can be obtained by measuring the radius of the circle. If the minimum cross-section is square, the minimum cross-sectional area can be obtained by measuring the length and width of the square.

[0190] As an example, the minimum cross-sectional area S of the first electrode terminal and / or the second electrode terminal can be 150 mm 2 、300 mm 2 、450 mm 2 、600 mm 2 、750 mm 2 、900 mm 2 、1000 mm 2 etc., or can be a range composed of any of the above values.

[0191] According to some embodiments of the present application, the volumetric energy density of the battery cell is 400 Wh / L - 530 Wh / L.

[0192] In this application, when testing the volumetric energy density of the battery cell, the battery cell is placed at 25°C and charged at a constant current of 0.33C to 3.65V, then charged at a constant voltage of 3.65V to 0.05C and left standing for 30 min; discharged at a constant current of 0.33C to 2.0V, and record the discharge capacity A at this time 0 , unit: Ah; use a caliper to measure the length, width, and height of the battery cell, and calculate the volume V of the single battery cell 0 , unit L; the volumetric energy density VED of the battery cell = (A 0 × discharge platform voltage) / V 0 , unit Wh / L.

[0193] According to some embodiments of the present application, the charging time of the battery cell from 10% SOC to 80% SOC is 5 min - 15 min.

[0194] The battery cell proposed in this application can be used in electrical equipment using the battery cell as a power source or various energy storage systems using the battery as an energy storage element. The electrical equipment can include but is not limited to mobile phones, tablets, laptop computers, electric toys, power tools, battery cars, electric vehicles, ships, spacecraft, etc. Among them, the electric toys can include fixed or mobile electric toys, such as game consoles, electric vehicle toys, electric ship toys, and electric aircraft toys, etc. The spacecraft can include airplanes, rockets, space shuttles, and spaceships, etc.

[0195] The second aspect of the present application provides a battery device, including the battery cell provided by the first aspect of the present application, and the battery device is one or more of a battery module, a battery pack, and an energy storage device.

[0196] The third aspect of the present application provides an electrical device, including the battery cell provided by the first aspect of the present application or the battery device provided by the second aspect of the present application, and the battery cell or the battery device provides electrical energy for the electrical device.

[0197] The electrical device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc., but is not limited thereto.

[0198] As the electrical device, the battery device can be selected according to its usage requirements.

[0199] Figure 14 is an electrical device as an example. The electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the high power and high energy density requirements of the electrical device for the battery, a battery pack or a battery module can be used.

[0200] Another example of the device can be a mobile phone, a tablet computer, a laptop computer, etc. This device usually requires thin and light design, and a battery cell can be used as the power source.

[0201] 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 embodiments and drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and shall in no way be construed as a limitation to 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 efforts shall fall within the protection scope of the present application.

[0202] Embodiment 1 1. Preparation of the positive electrode sheet The positive electrode sheet includes a positive electrode current collector, a positive electrode active material layer, and a positive electrode conductive layer. The positive electrode active material layer is disposed on both sides of the positive electrode current collector, and the positive electrode conductive layer is located between the positive electrode current collector and the positive electrode active material layer. The positive electrode current collector is aluminum foil.

[0203] The positive electrode conductive layer on the positive electrode current collector is a film layer formed by uniformly mixing a positive electrode conductive agent, superconducting carbon, a positive electrode binder, polyvinylidene fluoride (PVDF), and a solvent, N-methylpyrrolidone (NMP), and then coating and drying on the surface of the positive electrode current collector. The thickness is 1 μm. The mass content of the positive electrode conductive agent in the positive electrode conductive layer is 40%, and the mass content of the positive electrode binder is 60%.

[0204] The positive electrode active material layer includes a film layer formed by uniformly coating a positive electrode paste (with the solvent being NMP) on the surface of the positive electrode conductive layer, followed by drying and cold pressing. The positive electrode active material layer includes a positive electrode active material, a binder polyvinylidene fluoride (PVDF), and a conductive agent acetylene black with a mass ratio of 97:2:1. Along the length direction of the battery cell, the size of the positive electrode active material layer is 300 mm.

[0205] The positive electrode active material includes lithium iron phosphate particles and a first coating material. The first coating material coats the surface of the lithium iron phosphate particles. The first coating material includes lithium 2 FeTi(PO 4 ) 3 and carbon, and the mass content of carbon element is 1.12%.

[0206] The single-sided coating weight of the positive electrode active material layer is 263 mg / 1540.25 mm 2 .

[0207] The compaction density of the positive electrode active material layer is 2.46 g / cm 3 .

[0208] 2. Preparation of the negative electrode tab The negative electrode tab includes a negative electrode current collector, a negative electrode active material layer, and a negative electrode conductive layer. The negative electrode active material layer is arranged on both sides of the negative electrode current collector, and the negative electrode conductive layer is located between the negative electrode current collector and the negative electrode active material layer. The negative electrode current collector is a copper foil.

[0209] The negative electrode conductive layer on the negative electrode current collector is a film layer formed by uniformly mixing a negative electrode conductive agent, superconducting carbon, a negative electrode binder, styrene-butadiene rubber (SBR), a thickening agent, sodium carboxymethyl cellulose (CMC-Na), and a solvent, water, and then coating and drying on the surface of the negative electrode current collector. The thickness is 1 μm. The mass content of the negative electrode conductive agent in the negative electrode conductive layer is 35%, the mass content of the negative electrode binder in the negative electrode conductive layer is 60%, and the mass content of the thickening agent in the negative electrode conductive layer is 5%.

[0210] The negative electrode active material layer includes a film layer formed by uniformly coating a negative electrode paste (with the solvent being deionized water) on the surface of the negative electrode conductive layer, followed by drying and cold pressing.

[0211] The negative electrode active material layer comprises a negative electrode active material, acetylene black as a conductive agent, styrene-butadiene rubber as a negative electrode binder, and sodium carboxymethyl cellulose as a thickening agent, with a mass ratio of 96.5:0.5:2:1. The graphite particles include artificial graphite and a second coating material, and the second coating material coats the surface of the artificial graphite. The mass content of carbon element in the second coating material is 3.5%, and the Dv50 of the graphite particles is 11.3 μm.

[0212] The single-sided coating weight of the negative electrode active material layer is 120 mg / 1540.25 mm 2 。

[0213] The tap density of the negative electrode active material layer is 1.35 g / cm 3 。

[0214] The length of the negative electrode active material layer is 4 mm larger than that of the positive electrode active material layer, and the width of the negative electrode active material layer is 3 mm larger than that of the positive electrode active material layer.

[0215] 3. Separator The separator includes a base film and functional layers provided on both sides of the base film. The base film includes a 7-μm polyethylene film layer with a porosity of 42%; The functional layer includes a first functional layer and a second functional layer. The first functional layer includes alumina particles and polyvinylidene fluoride as a binder. The first functional layer is a film layer formed by coating a first slurry on one side of the base film, with a thickness of 1 μm and an average particle size of 10 nm for the alumina particles; among them, the first slurry includes alumina particles and polyvinylidene fluoride as a binder; The second functional layer is a composite particle formed by polyacrylate and calcium oxide particles dispersed on the polyacrylate. The second functional layer is a film layer formed by coating a second slurry on the other side of the base film, with a thickness of 5 μm and an average particle size of 10 nm for the calcium oxide particles; the second slurry includes the composite particles.

[0216] 4. Preparation of electrolyte The electrolyte includes an organic solvent, a lithium salt, and an additive.

[0217] After mixing the components of each organic solvent, a lithium salt and an additive are added to prepare the electrolyte.

[0218] The organic solvent includes a chain carboxylic ester solvent (ethyl acetate) with a mass content of 39%, ethylene carbonate EC with a mass content of 27.3%, and dimethyl carbonate with a mass content of 11.7%. The mass contents of each component in the organic solvent are calculated based on the mass of the electrolyte.

[0219] The mass content of the additive is 7%, and it includes vinylene carbonate VC, fluoroethylene carbonate FEC, ethylene sulfite ES, and lithium difluorooxalate borate LiDFOB with a mass ratio of 4:2:0.5:0.5.

[0220] The lithium salt includes 6% by mass of lithium bis(fluorosulfonyl)imide LiFSI and 9% of lithium hexafluorophosphate LiPF 6 , and the mass content of the lithium salt is calculated based on the mass of the electrolyte solution.

[0221] The viscosity of the electrolyte solution at room temperature is 2.72 mPa·s.

[0222] 5. Preparation of the battery cell Stack the above-mentioned positive electrode sheet, separator, and negative electrode sheet in sequence, with the separator placed between the positive electrode sheet and the negative electrode sheet to play an isolation role, obtaining a stacked electrode assembly. Place the electrode assembly in a housing, and positive and negative terminals are provided on the housing. After baking, inject the electrolyte solution, and through processes such as vacuum packaging, standing, formation, and shaping, a battery cell is obtained.

[0223] The housing is an aluminum shell with a cuboid structure, and the thickness of the shell corresponding to the face with the largest area of the cuboid structure is 0.5 mm.

[0224] Performance test 1. Volume energy density Place the battery cell in Example 1 at 25°C, charge it at a constant current of 0.33C to 3.65V, then charge it at a constant voltage of 3.65V to 0.05C, and let it stand for 30 min; discharge it at a constant current of 0.33C to 2.0V, and record the discharge capacity A at this time 0 , unit: Ah; use a caliper to measure the length, width, and height of the battery cell, and calculate the volume V of the single battery 0 , unit L; the volume energy density VED of the battery cell = (A 0 × discharge platform voltage) / V 0 , unit Wh / L.

[0225] 2. Fast charging performance At 30°C, after cycling the battery cell in Example 1 200 times according to their respective charge and discharge strategies, then fully charge it to 100% SOC according to the corresponding charging strategy, disassemble the negative electrode sheet, unfold the negative electrode sheet, observe the lithium deposition area (grayish-white area), and measure the lithium deposition area. The degree of lithium deposition is as follows: No lithium deposition: lithium deposition area < 0.05%.

[0226] Slight lithium deposition: lithium deposition area < 2%.

[0227] Severe lithium deposition: lithium deposition area ≥ 2%.

[0228] Charge the battery cell, and the charging steps include the following steps: Charge from 0% SOC to 40% SOC at a constant current of 5.0C; charge from 40% SOC to 45% SOC at a constant current of 4.6C; charge from 45% SOC to 50% SOC at a constant current of 4.3C; charge from 50% SOC to 55% SOC at a constant current of 4.0C; charge from 55% SOC to 60% SOC at a constant current of 3.7C; charge from 60% SOC to 65% SOC at a constant current of 3.4C; charge from 65% SOC to 70% SOC at a constant current of 3.1C; charge from 70% SOC to 75% SOC at a constant current of 2.9C; charge from 75% SOC to 80% SOC at a constant current of 2.7C; charge from 80% SOC to 85% SOC at a constant current of 1.8C; charge from 85% SOC to 90% SOC at a constant current of 1.3C; charge from 90% SOC to 95% SOC at a constant current of 0.7C; charge from 95% SOC to 98% SOC at a constant current of 0.33C; charge from 98% SOC to 100% SOC at a constant current of 0.1C.

[0229] The cut-off voltage of the last charging step in the above charging steps is 3.65V.

[0230] The discharging strategy is as follows: discharge at a constant current of 0.33C to the cut-off voltage, such as 2.0V.

[0231] When performing charge and discharge tests on the battery cell, the battery cell can be assembled in a battery device, and the required charge and discharge strategies can be regulated through the battery management system for testing.

[0232] 3. Cycling performance At 60°C, charge the battery cell at a constant current of 0.8C to the charge cut-off voltage of 3.6V, then charge at a constant current of 0.1C to the charge cut-off voltage of 3.65V, and let it stand for 30 min; discharge at a constant current of 1C to 3.1V and let it stand for 30 min. This is one charge and discharge cycle. Repeat the above charge and discharge cycle steps until the cycle capacity retention rate (i.e., C n / C 0 ×100%) is 70%, and record the number of cycles. The more the number of cycles, the better the cycling performance of the battery cell.

[0233] 4. Mass ratio of lithium fluorosulfonylimide and lithium hexafluorophosphate Disassemble the battery cell that has been discharged (discharged to the discharge cut-off voltage so that the charged state of the battery cell is approximately 0% SOC). The free electrolyte obtained from the battery cell is used as a sample, and it is detected by ion chromatography analysis method. Refer to the standard JY / T020 - 1996 "General Rules for Ion Chromatography Analysis Method", and then calculate the ratio of the mass ratio of lithium fluorosulfonylimide to the mass ratio of lithium hexafluorophosphate.

[0234] 5. Viscosity of the electrolyte Determine the viscosity of the electrolyte at room temperature by the rotational viscometer method provided in the national standard GB / T 10247-2008 "Viscosity Measurement Method". Specifically, take a certain mass of electrolyte sample and place it in a sample container, and place it in a hydrothermal bath for constant temperature and static placement for 10-20 minutes. Wait until the sample temperature is the same as the hydrothermal temperature, and use a rotational viscometer with the model DV2TLV produced by Brookfield Company for testing. When the 18th rotor rotates continuously in the sample at a constant speed of 70 r, the shear force generates torque on the spring, and the torque is proportional to the viscosity, obtaining the viscosity value. Test 5 samples, and the viscosity is the average value of the 5 samples. The test equipment meets the following test environmental conditions: 1. Equipment external environment: temperature is 15-28 °C, humidity is RH < 80%; 2. Equipment internal environment: 2 / 3 of the sample container is immersed in the water bath pot, the medium is water, and water is used to keep the sample at a constant temperature, and the hydrothermal temperature is room temperature.

[0235] Example 2 The preparation method of the battery cell is the same as that of Example 1, except that the size of the positive active material layer is 400 mm.

[0236] Example 3 The preparation method of the battery cell is the same as that of Example 1, except that the size of the positive active material layer is 500 mm.

[0237] Example 4 The preparation method of the battery cell is the same as that of Example 1, except that the size of the positive active material layer is 950 mm.

[0238] Comparative Example 1 The preparation method of the battery cell is the same as that of Example 1, except that the size of the positive active material layer is 200 mm.

[0239] Comparative Example 2 The preparation method of the battery cell is the same as that of Example 1, except that the size of the positive active material layer is 1050 mm.

[0240] The test results of the battery cells in Examples 1-4, Comparative Example 1, and Comparative Example 2 are shown in Table 1.

[0241] Table 1

[0242] As can be seen from Table 1, when the content of lithium salt, the ratio of the content of lithium fluorosulfonylimide to the content of lithium hexafluorophosphate, and the viscosity of the electrolyte in the electrolyte are within the protection scope of the present application, by adjusting the size of the positive electrode active material layer, a battery cell with a relatively high energy density and a good cycle life can be obtained. If the size of the positive electrode active material layer is too small, although the cycle life of the battery cell is good, the volumetric energy density of the battery cell is relatively low; if the size of the positive electrode active material layer is too large, although the volumetric energy density of the battery cell is relatively high, the positive electrode tab is long, and the transmission paths of electrons and ions on the side far from the tab are long, resulting in serious lithium deposition, which will reduce the fast charging performance and cycle performance of the battery cell.

[0243] Comparative Example 3 The preparation method of the battery cell is the same as that of Example 1, except that the size of the positive electrode active material layer is 610 mm, the electrolyte does not contain lithium fluorosulfonylimide salt, the mass ratio of lithium hexafluorophosphate is 15%, and the viscosity of the electrolyte is 2.73 mPa·s.

[0244] Example 5 The preparation method of the battery cell is the same as that of Example 1, except that the size of the positive electrode active material layer is 610 mm, the mass ratio of LiFSI in the electrolyte is 4%, the mass ratio of lithium hexafluorophosphate is 10%, the ratio of the mass ratio of LiFSI to lithium hexafluorophosphate is 0.4, and the mass ratio of dimethyl carbonate is 12.7%.

[0245] Example 6 The preparation method of the battery cell is the same as that of Example 1, except that the size of the positive electrode active material layer is 610 mm, the mass ratio of LiFSI in the electrolyte is 8%, the mass ratio of lithium hexafluorophosphate is 10%, the ratio of the mass ratio of LiFSI to lithium hexafluorophosphate is 0.8, and the mass ratio of dimethyl carbonate is 8.7%.

[0246] Example 7 The preparation method of the battery cell is the same as that of Example 1, except that the size of the positive electrode active material layer is 610 mm, and the type of lithium bis(fluorosulfonyl)imide salt in the electrolyte is LiTFSI.

[0247] Comparative Example 4 The preparation method of the battery cell is the same as that of Example 1, except that the size of the positive electrode active material layer is 610 mm, the mass ratio of LiFSI in the electrolyte is 4%, the mass ratio of lithium hexafluorophosphate is 4%, the ratio of the mass ratio of LiFSI to lithium hexafluorophosphate is 1, and the mass ratio of dimethyl carbonate is 18.7%.

[0248] Comparative Example 5 The preparation method of the battery cell is the same as that of Example 1, except that the size of the positive active material layer is 610 mm, the mass ratio of LiFSI in the electrolyte is 2%, the mass ratio of lithium hexafluorophosphate is 8%, the ratio of the mass ratio of LiFSI to the mass ratio of lithium hexafluorophosphate is 0.25, and the mass ratio of dimethyl carbonate is 16.7%.

[0249] Comparative Example 6 The preparation method of the battery cell is the same as that of Example 1, except that the size of the positive active material layer is 610 mm, the mass ratio of LiFSI in the electrolyte is 6%, the mass ratio of lithium hexafluorophosphate is 14%, the ratio of the mass ratio of LiFSI to the mass ratio of lithium hexafluorophosphate is 0.43, and the mass ratio of dimethyl carbonate is 6.7%.

[0250] The test results of the battery cells in Examples 5 - 7 and Comparative Examples 3 - 6 are shown in Table 2.

[0251] Table 2

[0252] As can be seen from Table 2, when the size of the positive active material layer is within the range defined in this application, if the electrolyte does not contain lithium fluorosulfonylimide salt or the ratio of the content of lithium fluorosulfonylimide salt to the content of lithium hexafluorophosphate is small, due to the long length of the electrode sheet, the wetting effect of the electrolyte on the long electrode sheet is limited, which will cause serious lithium deposition. By increasing the content of lithium fluorosulfonylimide salt in the electrolyte, since the ion transference number of lithium fluorosulfonylimide salt is large, the migration rate of lithium ions in the electrolyte can be increased, the probability of lithium deposition can be reduced, and a battery cell with good fast charging performance and cycle life can be obtained. If the content of lithium fluorosulfonylimide salt in the electrolyte is too much, the severity of thermal runaway of lithium fluorosulfonylimide salt is more intense than that of lithium hexafluorophosphate, which will reduce the safety of the battery cell.

[0253] As can be seen from Example 7, different types of lithium fluorosulfonylimide salts can all play a role in increasing the migration rate of lithium ions and improving the wetting effect of the electrolyte on the positive electrode sheet, thereby reducing the occurrence of lithium deposition.

[0254] Example 8 The preparation method of the battery cell is the same as that of Example 1, except that the size of the positive active material layer is 610 mm and the type of the first solvent is methyl acetate.

[0255] Comparative Example 7 The preparation method of the battery cell is the same as that of Example 1, except that the mass ratio of LiFSI is 4%, the mass ratio of lithium hexafluorophosphate is 8%, the mass ratio of ethyl acetate is 2%, the mass ratio of ethylene carbonate is 23.3%, and the mass ratio of dimethyl carbonate is 55.7%.

[0256] Example 9 The preparation method of the battery cell is the same as that of Example 1, except that the mass ratio of LiFSI is 4%, the mass ratio of lithium hexafluorophosphate is 8%, the mass ratio of ethyl acetate is 8%, the mass ratio of ethylene carbonate is 23.3%, and the mass ratio of dimethyl carbonate is 49.7%.

[0257] Example 10 The preparation method of the battery cell is the same as that of Example 1, except that the mass ratio of ethyl acetate is 30% and the mass ratio of dimethyl carbonate is 20.7%.

[0258] Example 11 The preparation method of the battery cell is the same as that of Example 1, except that the mass ratio of ethyl acetate is 60%, the mass ratio of ethylene carbonate is 18%, and the electrolyte does not contain dimethyl carbonate.

[0259] The detailed differences and test results of the battery cells in Examples 8 - 11 and Comparative Example 5 are shown in Tables 3 and 4.

[0260] Table 3

[0261] Table 4

[0262] As can be seen from Table 4, as the content of the first solvent increases, the viscosity of the electrolyte gradually decreases, which can improve the migration rate of lithium ions. By adjusting the contents of the first solvent and the second solvent in the electrolyte, the cycle performance of the battery cell can be improved, and the occurrence of lithium plating can be reduced. In addition, by comparing Example 9 with Example 5, it can be known that the viscosity of the electrolyte is 2.3 mPa·s - 3.5 mPa·s, which can improve the fast charging performance and cycle life of the battery.

[0263] Example 12 The preparation method of the battery cell is the same as that of Example 1, except that the size of the positive electrode active material layer is 610 mm, the mass ratio of dimethyl carbonate is 9.7%, the mass ratio of VC is 5%, and the mass ratio of FEC is 3%.

[0264] Example 13 The preparation method of the battery cell is the same as that of Example 1, except that the size of the positive electrode active material layer is 610 mm, the mass ratio of dimethyl carbonate is 10.2%, and the mass ratio of ES is 2%.

[0265] Example 14 The preparation method of the battery cell is the same as that of Example 1, except that the size of the positive active material layer is 610 mm, the mass ratio of dimethyl carbonate is 12%, and the mass ratio of LiDFOB is 0.2%.

[0266] Example 15 The preparation method of the battery cell is the same as that of Example 1, except that the size of the positive active material layer is 610 mm, the mass ratio of dimethyl carbonate is 11.2%, and the mass ratio of LiDFOB is 1%.

[0267] The detailed differences and test results of the battery cells in Examples 12 - 15 are shown in Tables 5 and 6.

[0268] Table 5

[0269] Table 6

[0270] As can be seen from Tables 5 and 6, when the size of the positive active material layer, the ratio of the mass ratios of lithium fluorosulfonylimide salt and lithium hexafluorophosphate, the content of the lithium salt, and the viscosity of the electrolyte are within the ranges defined in this application, the contents of the carbonate additive, the sulfur - containing additive, and the lithium - salt additive in the electrolyte can be adjusted. The additives can improve the stability of the SEI film, thereby improving the cycle life of the battery cell.

Claims

1. A battery cell, comprising an electrode assembly and an electrolyte, wherein the electrode assembly comprises a positive electrode sheet, characterized in that: The positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer disposed on at least one side of the positive electrode current collector, and the size of the positive electrode active material layer along the length direction of the battery cell is 300 mm-950 mm; The electrolyte includes a lithium salt, and based on the total mass of the electrolyte, the mass proportion of the lithium salt is 10%-18%; the lithium salt includes a fluorinated sulfonyl imide lithium salt and lithium hexafluorophosphate, and based on the total mass of the electrolyte, the ratio of the mass proportion of the fluorinated sulfonyl imide lithium salt to the mass proportion of the lithium hexafluorophosphate is 0.4-1.0, and the viscosity of the electrolyte at room temperature is 2.3mPa·s-3.5mPa·s.

2. The battery cell according to claim 1, characterized in that: The electrolyte includes a first solvent, the viscosity of the first solvent at room temperature is 0.3 mPa·s-0.6 mPa·s, and based on the total mass of the electrolyte, the mass proportion of the first solvent is 8%-60%.

3. The battery cell according to claim 1, characterized in that: The dimension of the positive electrode active material layer along the length direction of the battery cell is 400 mm to 950 mm.

4. The battery cell according to claim 1, characterized in that: The dimension of the positive electrode active material layer along the length direction of the battery cell is 500 mm to 950 mm.

5. The battery cell according to claim 2, characterized in that: The first solvent includes a carboxylate solvent.

6. The battery cell according to claim 5, characterized in that: The carboxylate solvent includes a compound shown in Formula I: Formula I, Among them, R5 includes any one of a hydrogen atom, a halogen atom, a C1-C5 alkyl group, and a C1-C5 halogenated alkyl group, and R6 includes any one of a C1-C5 alkyl group and a C1-C5 halogenated alkyl group.

7. The battery cell according to claim 5, characterized in that: The carboxylate solvent includes one or more of methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, and ethyl butyrate.

8. The battery cell according to claim 2, characterized in that: Based on the total mass of the electrolyte, the mass proportion of the first solvent is 30%-60%.

9. The battery cell according to claim 1, characterized in that: The fluorine-containing lithium sulfonyl imide salt includes one or more of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, and lithium perfluorobutylsulfonyl imide.

10. The battery cell according to claim 1, characterized in that: Based on the total mass of the electrolyte, the mass proportion of the fluorinated sulfonyl imide lithium salt is 4%-10%.

11. The battery cell according to claim 1, characterized in that: Based on the total mass of the electrolyte, the mass proportion of the fluorinated sulfonyl imide lithium salt is 4%-8%.

12. The battery cell according to claim 1, characterized in that: Based on the total mass of the electrolyte, the mass proportion of the lithium hexafluorophosphate is 8%-12%.

13. The battery cell according to claim 1, characterized in that: The electrolyte further includes a second solvent, the second solvent includes a carbonate solvent, and the carbonate solvent includes one or more of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

14. The battery cell according to claim 13, characterized in that: Based on the total mass of the electrolyte, the mass proportion of the carbonate solvent is 18%-75%.

15. The battery cell according to claim 1, characterized in that: The electrolyte further includes additives, and the additives include one or more of carbonate additives, sulfur-containing additives, and lithium salt additives.

16. The battery cell according to claim 15, characterized in that: The carbonate additive includes one or both of vinylene carbonate and vinyl carbonate derivatives.

17. The battery cell according to claim 15, characterized in that: Based on the total mass of the electrolyte, the mass proportion of the carbonate additive is 3%-8%.

18. The battery cell according to claim 16, characterized in that: Based on the total mass of the electrolyte, the mass proportion of the vinylene carbonate is 2%-5%.

19. The battery cell according to claim 16, characterized in that: The ethylene carbonate derivatives include compounds shown in formula II: Formula II, Wherein, R1, R2, R3, and R4 each independently include any one of a hydrogen atom, a halogen atom, a C1-C5 alkyl group, and a C1-C5 halogenated alkyl group, and R1, R2, R3, and R4 are not hydrogen atoms at the same time.

20. The battery cell according to claim 16, characterized in that: Based on the total mass of the electrolyte, the mass proportion of the ethylene carbonate derivative is 0%-4%.

21. The battery cell according to claim 16, characterized in that: Based on the total mass of the electrolyte, the mass proportion of the ethylene carbonate derivative is 1.5%-3.5%.

22. The battery cell according to claim 15, characterized in that: The sulfur-containing additive includes one or more of vinyl sulfate, vinyl disulfate, 1,3-propane sultone, butylene sulfite, vinyl sulfite, and methylene disulfonate.

23. The battery cell according to claim 15, characterized in that: Based on the total mass of the electrolyte, the mass proportion of the sulfur-containing additive is 0-2%.

24. The battery cell according to claim 15, characterized in that: Based on the total mass of the electrolyte, the mass proportion of the sulfur-containing additive is 0.5%-2%.

25. The battery cell according to claim 15, characterized in that: The lithium salt additive includes one or more of lithium difluorophosphate, lithium difluorooxalatoborate, lithium tetrafluoroborate, and lithium bis(oxalatoborate).

26. The battery cell according to claim 15, characterized in that: Based on the total mass of the electrolyte, the mass proportion of the lithium salt additive is 0-1%.

27. The battery cell according to claim 15, characterized in that: Based on the total mass of the electrolyte, the mass proportion of the lithium salt additive is 0.2%-1%.

28. The battery cell according to claim 1, characterized in that: The positive electrode active material layer includes a positive electrode active material, and the positive electrode active material includes a lithium-containing phosphate.

29. The battery cell according to claim 28, characterized in that: The lithium-containing phosphate comprises: matrix; A first coating material is located on at least a portion of the surface of the substrate, and the first coating material contains carbon.

30. The battery cell according to claim 29, characterized in that Based on the total mass of the lithium-containing phosphate, the mass proportion of the carbon element is 0.8%-2.3%.

31. The battery cell according to claim 29, characterized in that: The first coating material includes a compound shown in formula III: Li 3-d1 Fe 2-d1 M1 d1 (PO m1 ) n1 Formula III Among them, 0≤d1≤1, 3≤m1≤5, 2≤n1≤4; M1 includes one or more of Ti, Zr, Hf, Ge, and Sn.

32. The battery cell according to claim 29, characterized in that: The matrix includes a compound shown in formula IV: Li x1 A y1 Me a1 M2 b1 P 1-c1 X c1 Y z1 Formula IV Among them, 0.5≤x1≤1.3, 0≤y1≤1.3, 0.9≤x1+y1≤1.3; 0.9≤a1≤1.5, 0≤b1≤0.5, 0.9≤a1+b1≤1.5; 0≤c1≤0.5; 3≤z1≤5; Among them, A includes one or more of Na, K, and Mg; Me includes one or more of Mn, Fe, Co, and Ni; M2 includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; X includes one or more of S, Si, Cl, B, C, N, and P; and Y includes one or more of O and F.

33. The battery cell according to claim 29, characterized in that: The matrix includes one or more of lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, lithium nickel phosphate, and lithium cobalt phosphate.

34. The battery cell according to claim 1, characterized in that The powder compaction density of the positive electrode active material at 30000N is 2.43g / cm 3 -2.85g / cm 3 .

35. The battery cell according to claim 1, characterized in that The single-sided coating weight of the positive electrode active material layer is 200 mg / 1540.25 mm 2 -350mg / 1540.25mm 2 .

36. The battery cell according to claim 1, characterized in that The electrode assembly also includes a negative electrode plate, which includes a negative electrode collector and a negative electrode active material layer arranged on at least one side of the negative electrode collector. The negative electrode active material layer includes a negative electrode active material, and the negative electrode active material includes a carbon-based material and / or a silicon-based material.

37. The battery cell according to claim 36, characterized in that: The carbon-based material includes graphite.

38. The battery cell according to claim 37, characterized in that: The graphite is a secondary particle formed by aggregation of primary particles, at least a portion of the surface of the secondary particle has a second coating material, and the second coating material includes amorphous carbon.

39. The battery cell according to claim 38, characterized in that Based on the total mass of the graphite, the mass proportion of the second coating material is 2%-5%.

40. The battery cell according to claim 37, characterized in that The volume average particle size Dv50 of the graphite is 8.5 μm-13.8 μm.

41. The battery cell according to claim 36, characterized in that Based on the total mass of the negative electrode active material layer, the mass proportion of silicon element is 0.3%-5%.

42. The battery cell according to claim 36, characterized in that The single-sided coating weight of the negative electrode active material layer is 90 mg / 1540.25 mm 2 -140mg / 1540.25mm 2 .

43. The battery cell according to claim 36, characterized in that Along the length direction of the battery cell, the size of the negative electrode active material layer is greater than the size of the positive electrode active material layer, and the difference between the size of the negative electrode active material layer and the size of the positive electrode active material layer is OH1; Along the width direction of the battery cell, the size of the negative electrode active material layer is larger than the size of the positive electrode active material layer, and the difference between the size of the negative electrode active material layer and the size of the positive electrode active material layer is OH2, Among them, OH1 is greater than or equal to OH2.

44. The battery cell according to claim 43, characterized in that 1mm≤OH1≤4mm, 1mm≤OH2≤3mm.

45. The battery cell according to claim 36, characterized in that The positive electrode sheet is provided with a positive electrode tab, and the negative electrode sheet is provided with a negative electrode tab, the positive electrode tab extends along the length direction of the positive electrode sheet or along its width direction; and / or the negative electrode tab extends along the length direction of the negative electrode sheet or along its width direction.

46. ​​The battery cell according to claim 45, characterized in that Along the length direction of the battery cell, the length of the positive electrode active material layer is greater than 500 mm, and the positive electrode tabs extend from both ends in the length direction or both ends in the width direction of the positive electrode sheet.

47. The battery cell according to claim 45, characterized in that Along the length direction of the battery cell, the length of the positive electrode active material layer is less than or equal to 500 mm, and the positive electrode tab extends from one end in the length direction or one end in the width direction of the positive electrode sheet, or the positive electrode tab extends from both ends in the length direction or both ends in the width direction of the positive electrode sheet.

48. The battery cell according to claim 1, characterized in that The electrode assembly further includes a separator having a porosity of 20% to 70%.

49. The battery cell according to claim 48, characterized in that The porosity of the isolation membrane is 35%-60%.

50. The battery cell according to claim 48, characterized in that The isolation film comprises: Basement membrane; A first functional layer, located on at least one side of the base film, wherein the first functional layer comprises a first inorganic substance; The second functional layer is located on a side of the first functional layer away from the base film, and the second functional layer includes a second inorganic substance and a non-fluorine polymer.

51. The battery cell according to claim 50, characterized in that The non-fluorine polymer includes an acrylic copolymer.

52. The battery cell according to claim 50, characterized in that The first inorganic substance and the second inorganic substance independently include one or more of silicon oxide, aluminum oxide, boehmite, barium sulfate, calcium oxide, titanium oxide, zinc oxide, magnesium oxide, zirconium oxide, and tin oxide.

53. The battery cell according to claim 50, characterized in that The base film has a thickness of 4 μm-12 μm.

54. The battery cell according to claim 1, characterized in that The battery cell comprises a shell and a cover assembly, wherein the cover assembly is arranged at at least one end of the shell, the shell and the cover assembly define a receiving cavity, the electrode assembly is arranged in the receiving cavity, and the shell thickness of the large surface of the battery cell is 0.1mm-0.5mm.

55. The battery cell according to claim 54, characterized in that The shell thickness of the large surface of the battery cell is 0.2mm-0.35mm.

56. The battery cell according to claim 54, characterized in that The cover plate assembly includes a first cover plate assembly and a second cover plate assembly, the first cover plate assembly and the second cover plate assembly are arranged at both ends of the length direction or the width direction of the shell, the first cover plate assembly includes a first cover plate and a first electrode terminal, the second cover plate assembly includes a second cover plate and a second electrode terminal, and the polarities of the first electrode terminal and the second electrode terminal are opposite.

57. The battery cell according to claim 56, characterized in that The minimum cross-sectional area of ​​the first electrode terminal and / or the second electrode terminal is S and meets the requirement of 150 mm 2 ≤S≤1000mm 2 .

58. The battery cell according to claim 1, characterized in that The volume energy density of the battery cell is 400Wh / L-530Wh / L.

59. The battery cell according to claim 1, characterized in that The charging time of the battery cell from 10% SOC to 80% SOC is 5 min-15 min.

60. A battery device, characterized in that: Comprising the battery monomer described in any one of claims 1-59, the battery device is one or more of a battery module, a battery pack, and an energy storage device.

61. An electrical device, characterized in that: The battery cell comprises the battery cell described in any one of claims 1 to 59 or the battery device described in claim 60, wherein the battery cell or the battery device provides electrical energy for the electrical equipment.

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