Battery, method of manufacturing the same, and electric device including the same

Abstract

The application provides a battery, a preparation method thereof, and a power utilization device comprising the same. The battery comprises a positive electrode sheet and an electrolyte. The positive electrode sheet comprises a positive electrode current collector, and the positive electrode current collector comprises a conductive layer. The electrolyte comprises a first anion and a second anion. The first anion comprises a hexafluorophosphate anion. The second anion comprises one or more selected from anions represented by formula 1 and anions represented by formula 2. The thickness of the conductive layer is H1 μm. The concentration of the first anion in the electrolyte is C1 mol / L, and the concentration of the second anion is C2 mol / L. The battery satisfies 0.2 x (C2 / C1) ≤ H1 ≤ (C2 / C1) + 3. The application can improve the safety performance of the battery while ensuring good electrochemical performance of the battery.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of batteries, and particularly relates to a battery, a preparation method thereof, and an electric device comprising the same. BACKGROUND

[0002] In recent years, batteries are widely used in energy storage power systems such as hydroelectric, thermal, wind and solar power stations, and in many fields such as electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc. With the application and promotion of batteries, more and more attention is paid to their safety. If the safety of a battery cannot be guaranteed, the battery cannot be used. Therefore, how to enhance the safety performance of the battery while not affecting the electrochemical performance of the battery is a technical problem to be solved at present. SUMMARY

[0003] The present application aims to provide a battery, a preparation method thereof, and an electric device comprising the same, which can reduce the influence of positive electrode current collector corrosion on the safety performance and electrochemical performance of the battery, thereby improving the safety performance of the battery while ensuring good electrochemical performance.

[0004] The first aspect of the present application provides a battery comprising a positive electrode sheet and an electrolyte, wherein the positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer arranged on at least one surface of the positive electrode current collector, the positive electrode current collector comprises a conductive layer, the electrolyte comprises a solvent and a solute, the solute is an ionic salt formed by a cation and an anion, the cation comprises one or more selected from alkali metal cations and alkaline earth metal cations, and optionally comprises one or more selected from lithium ions, sodium ions and potassium ions, the anion comprises a first anion and a second anion, the first anion comprises a hexafluorophosphate anion, the second anion comprises one or more selected from anions represented by Formula 1 and anions represented by Formula 2, R1, R2 and R3 independently represent a fluorine atom or a C1-C5 fluorine-containing alkyl group, R1 and R2 can also be bonded to form a ring, the thickness of the conductive layer is H1 μm, the concentration of the first anion in the electrolyte is C1 mol / L, the concentration of the second anion is C2 mol / L, and the battery satisfies 0.2 x (C2 / C1) ≤ H1 ≤ (C2 / C1) + 3.

[0005]

[0006] The inventors of the present application surprisingly found through a large number of experiments that by adjusting the thickness H1 of the conductive layer, the relationship between the concentration C1 of the first anion and the concentration C2 of the second anion to satisfy 0.2 x (C2 / C1) ≤ H1 ≤ (C2 / C1) + 3, the influence of the corrosion of the conductive layer on the safety performance and electrochemical performance of the battery can be reduced, thereby the battery can have good electrochemical performance while improving the safety performance of the battery, for example, the battery can have a longer service life.

[0007] In any embodiment of the present application, 0.2 x (C2 / C1) + 0.2 ≤ H1 ≤ (C2 / C1) + 2. Thereby, the influence of the corrosion of the conductive layer on the safety performance and electrochemical performance of the battery can be further reduced.

[0008] In any embodiment of the present application, 0.2 ≤ H1 ≤ 8, and optionally, 1 ≤ H1 ≤ 5. Thereby, the battery can have good electrochemical performance while improving the safety performance of the battery.

[0009] In any embodiment of the present application, 0.1 ≤ C1 ≤ 1. The first anion helps to improve the ionic conductivity of the electrolyte, accelerate ion transmission, and improve the capacity of the battery.

[0010] In any embodiment of the present application, 0.1 ≤ C2 ≤ 1.5, and optionally, 0.5 ≤ C2 ≤ 1.5. The second anion can improve the ionic dissociation degree of the electrolyte, reduce the viscosity of the electrolyte, improve the ionic conductivity of the electrolyte, and in addition, the second anion also has the characteristics of good high-temperature resistance and not easy to hydrolyze, thereby the cycle performance of the battery can be improved.

[0011] In any embodiment of the present application, 0.6 ≤ C1 + C2 ≤ 2.5, and optionally, 0.6 ≤ C1 + C2 ≤ 2.0.

[0012] In any embodiment of the present application, 0.1 ≤ C2 / C1 ≤ 5, and optionally, 0.5 ≤ C2 / C1 ≤ 5.

[0013] When the concentration of the first anion and the concentration of the second anion satisfy 0.6 ≤ C1 + C2 ≤ 2.5 and / or 0.1 ≤ C2 / C1 ≤ 5, the corrosion of the conductive layer can be inhibited to a certain extent, the safety performance of the battery can be improved, and at the same time, the battery can also maintain excellent cycle performance.

[0014] In any embodiment of the present application, the positive current collector further comprises an organic support layer, the conductive layer is disposed on at least one surface of the organic support layer, and the conductive layer is further disposed between the organic support layer and the positive active material layer. In this way, the safety performance of the battery can be further improved, and the problem of thermal runaway caused by short circuit between the positive electrode and the negative electrode can be avoided.

[0015] In any embodiment of the present application, the thickness of the organic support layer is H2μm, and the battery satisfies 0.1≤H1 / H2≤1, and optionally, 0.2≤H1 / H2≤0.6. In this way, the battery can have good electrochemical performance while improving the safety performance of the battery.

[0016] In any embodiment of the present application, the thickness of the organic support layer is H2μm, and 1≤H2≤10, and optionally, 4≤H2≤7. In this way, the battery can have high energy density while improving the safety performance of the battery.

[0017] In any embodiment of the present application, the total thickness of the positive current collector is H0μm, and 5≤H0≤15, and optionally, 9≤H0≤15.

[0018] In any embodiment of the present application, the total thickness of the positive current collector is H0μm, the positive current collector has an elongation at break S0, and the battery satisfies 5S0–(H0 / 10)≤C1 / C2≤100S0+(H0 / 9). When the battery further satisfies 5S0–(H0 / 10)≤C1 / C2≤100S0+(H0 / 9), the influence of corrosion of the conductive layer on the safety performance and electrochemical performance of the battery can be further reduced, and thus the battery can have better safety performance and electrochemical cycle performance.

[0019] In any embodiment of the present application, 2%≤S0≤3.5%.

[0020] In any embodiment of the present application, the organic support layer comprises one or more of a high polymer material and a high polymer-based composite material.

[0021] In any embodiment of the present application, the high molecular material includes one or more selected from the group consisting of polyolefins, polyacetylenes, polyesters, polycarbonates, polyacrylates, polyamides, polyimides, polyethers, polyalcohols, polysulfones, polythia sulfides, polysaccharide polymers, amino acid polymers, aromatic ring polymers, aromatic heterocyclic polymers, epoxy resins, phenol resins, polyurethanes, thermoplastic elastomers, rubbers, derivatives of the above materials, cross-linked products of the above materials, and copolymers of the above materials, and optionally includes one or more selected from the group consisting of polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, polyacetylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polymethyl methacrylate, polycaprolactam, polyhexamethylene adipamide, poly-para-phenyleneterephthalamide, polyformaldehyde, polyphenylene ether, polyphenylene sulfide, polyethylene glycol, polyvinyl alcohol, poly-4-hydroxybenzoic acid, poly-2-hydroxy-6-naphthoic acid, polyaniline, polypyrrole, polythiophene, polyphenyl, polystyrene sulfonate sodium, cellulose, starch, acrylonitrile-butadiene-styrene copolymer, derivatives of the above materials, cross-linked products of the above materials, and copolymers of the above materials,

[0022] In any embodiment of the present application, the high molecular-based composite material includes the high molecular material and an additive, and the additive includes one or more selected from the group consisting of metal materials and inorganic non-metal materials.

[0023] In any embodiment of the present application, the conductive layer includes one or more selected from the group consisting of metal materials, and optionally includes one or more selected from the group consisting of aluminum, silver, nickel, titanium, stainless steel, aluminum alloy, silver alloy, nickel alloy, and titanium alloy.

[0024] In any embodiment of the present application, R1, R2, and R3 each independently represent a fluorine atom, a trifluoromethyl group, a pentafluoroethyl group, or a heptafluoropropyl group.

[0025] In any embodiment of the present application, R1 and R2 are the same.

[0026] In any embodiment of the present application, the electrolyte further includes a third anion, and the third anion includes one or more selected from the group consisting of tetrafluoroborate anion, difluoro oxalate borate anion, di-oxalate borate anion, difluorophosphate anion, difluoro di-oxalate phosphate anion, and tetrafluoro oxalate phosphate anion. These anions help to form a protective film with excellent performance on the surface of the positive electrode and / or the negative electrode, thereby further improving at least one of the cycle performance, the rate performance, the storage performance, and the like of the battery.

[0027] In any embodiment of the present application, the battery further includes a negative electrode sheet and a separator film, and the separator film is located between the positive electrode sheet and the negative electrode sheet.

[0028] The second aspect of the present application provides a method for preparing a battery, comprising the following steps 1 and 2.

[0029] Step 1, assembling a battery by using a positive electrode sheet, a separator, a negative electrode sheet and an electrolyte.

[0030] The positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer arranged on at least one surface of the positive electrode current collector, and the positive electrode current collector comprises a conductive layer.

[0031] The electrolyte comprises a solvent and a solute, and the solute is an ionic salt formed by a cation and an anion, the cation comprises one or more selected from alkali metal cations and alkaline earth metal cations, and optionally comprises one or more selected from lithium ions, sodium ions and potassium ions, and the anion comprises a first anion and a second anion, the first anion comprises a hexafluorophosphate anion, and the second anion comprises one or more selected from anions represented by Formula 1 and anions represented by Formula 2, R1, R2 and R3 independently represent a fluorine atom or a C1-C5 fluorine-containing alkyl group, and R1 and R2 can also be bonded to form a ring.

[0032]

[0033] The thickness of the conductive layer is H1 μm, the concentration of the first anion in the electrolyte is C1 mol / L, and the concentration of the second anion is C2 mol / L.

[0034] Step 2, screening the battery from the battery obtained in step 1 to meet 0.2×(C2 / C1)≤H1≤(C2 / C1)+3, and optionally to meet 0.2×(C2 / C1)+0.2≤H1≤(C2 / C1)+2.

[0035] In any embodiment of the present application, the method further comprises step 3, screening the battery from the battery obtained in step 2 to meet at least one of the following conditions (1) to (9),

[0036] (1) 0.2≤H1≤8,

[0037] (2) 1≤H1≤5,

[0038] (3) 0.1≤C1≤1,

[0039] (4) 0.1≤C2≤1.5,

[0040] (5) 0.5≤C2≤1.5,

[0041] (6) 0.6≤C1+C2≤2.5,

[0042] (7) 0.6 ≤ C1 + C2 ≤ 2.0,

[0043] (8) 0.1 ≤ C2 / C1 ≤ 5,

[0044] (9) 0.5 ≤ C2 / C1 ≤ 5.

[0045] In any embodiment of the present application, in step 1, the positive current collector further comprises an organic support layer, the conductive layer is disposed on at least one surface of the organic support layer, and the conductive layer is also disposed between the organic support layer and the positive active material layer, the thickness of the organic support layer is H2μm, the total thickness of the positive current collector is H0μm, and the breaking elongation of the positive current collector is S0.

[0046] In any embodiment of the present application, the method further comprises: step 4, screening the battery obtained from step 2 or step 3 to obtain a battery satisfying at least one of the following conditions (1) to (8),

[0047] (1) 5S0–(H0 / 10) ≤ C1 / C2 ≤ 100S0+(H0 / 9),

[0048] (2) 0.1 ≤ H1 / H2 ≤ 1,

[0049] (3) 0.2 ≤ H1 / H2 ≤ 0.6,

[0050] (4) 1 ≤ H2 ≤ 10,

[0051] (5) 4 ≤ H2 ≤ 7,

[0052] (6) 5 ≤ H0 ≤ 15,

[0053] (7) 9 ≤ H0 ≤ 15,

[0054] (8) 2% ≤ S0 ≤ 3.5%.

[0055] The battery obtained by the preparation method of the present application has high safety performance and good electrochemical performance.

[0056] The third aspect of the present application provides a power utilization device comprising the battery of the first aspect of the present application or the battery prepared by the method of the second aspect of the present application.

[0057] The inventors of the present application surprisingly found through a large number of experiments that by adjusting the thickness H1 of the conductive layer, the relationship between the concentration C1 of the first anion and the concentration C2 of the second anion to satisfy 0.2 x (C2 / C1) ≤ H1 ≤ (C2 / C1) + 3, the influence of the corrosion of the conductive layer on the safety performance and electrochemical performance of the battery can be reduced, thereby improving the safety performance of the battery while ensuring good electrochemical performance. The power device of the present application comprises the battery provided by the present application, and thus at least has the same advantages as the battery. BRIEF DESCRIPTION OF DRAWINGS

[0058] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments of the present application will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by the drawings without creative labor for those skilled in the art.

[0059] Figure 1 is a schematic diagram of an embodiment of the battery cell of the present application.

[0060] Figure 2 is an exploded schematic diagram of an embodiment of the battery cell of the present application.

[0061] Figure 3 is a schematic diagram of an embodiment of the battery module of the present application.

[0062] Figure 4 is a schematic diagram of an embodiment of the battery pack of the present application.

[0063] Figure 5 is an exploded schematic diagram of an embodiment of the battery pack shown in Figure 4

[0064] Figure 6 is a schematic diagram of an embodiment of the positive electrode sheet of the present application.

[0065] Figure 7 is a schematic diagram of another embodiment of the positive electrode sheet of the present application.

[0066] Figure 8 is a schematic diagram of an embodiment of the power device comprising the battery of the present application as a power supply.

[0067] In the drawings, the drawings are not necessarily drawn according to the actual scale. The reference signs are explained as follows: 101 positive current collector, 102 positive active material layer, 1011 conductive layer, 1012 organic support layer, 1 battery pack, 2 upper box body, 3 lower box body, 4 battery module, 5 battery cell, 51 shell, 52 electrode assembly, 53 cover plate. ​DETAILED DESCRIPTION

[0068] Hereinafter, specific embodiments of the battery, the method of manufacturing the same, and the electric device including the same according to the present application will be described in detail with appropriate reference to the accompanying drawings. However, it will be understood that the detailed description is given to avoid unnecessarily obscuring the present application as required. For example, there will be omitted detailed description of matters well known to one of ordinary skill in the art, and repeated description of substantially the same structure. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by one of ordinary skill in the art. In addition, the accompanying drawings and the following description are provided to enable those skilled in the art to sufficiently understand the present application, and are not intended to limit the subject matter recited in the claims.

[0069] The ranges disclosed herein are defined by their lower and upper limits. Ranges created by combining these upper and lower limits are also part of the disclosure. For example, if a range is from 1 to 10, then 5-9 is also explicitly stated as part of the range. Moreover, the explicit combination of any two of the specified ranges and the inclusion of one or more of either or both of the stated limits for the two ranges is also within the scope of the disclosure. For example, if a range is from 1 to 10 and another range is from 4 to 12, then 4-8, 5-9, and 6- 10 are also explicitly stated as part of the range. Additionally, if a range is from 1 to 5 and another range is from 6 to 12, then 6- 10 is also explicitly stated as part of the range. Furthermore, where a range includes one or both of the stated limits, for example 2-10, it is explicitly disclosed that 2 is included in the range and 10 is included in the range. It is also disclosed that 2 and 10 are each excluded. For example, if a range is from 2-10 it is explicitly disclosed that 2 and 10 are each excluded from the range. In addition, the statements of a range include both the endpoints and all the numbers between and leading up to each endpoint. For example, a range of 4-8 includes 4, 5, 6, and 7, and also includes 4, 5, 6 and 7. Furthermore, it is specifically intended that the description of a range include all of the possible sub-ranges as is within the purview of one of ordinary skill in the art. For example, a range of "1 to 10" is intended to include any and all sub-ranges between (and including) the recited minimum value of 1 and the recited maximum value of 10, that is, all sub-ranges having a limit of 1 or higher and a limit of 10 or lower, in increments of one, including by way of example only 3-7, 5-11, 10-5, 9-9, 2-2, 7-3, and 1-10. In certain embodiments, a range is limited to the narrower of the two ranges, even if that narrower range is not expressly stated. For example, a range of "about 1.5 to 10" is intended to include all sub-ranges between (and including) the recited minimum value of about 1.5 and the recited maximum value of 10, and is also intended to

[0070] If not specifically explained, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present application.

[0071] If not specifically explained, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present application.

[0072] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0073] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0074] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0075] In this application, the terms "multiple" or "various" refer to two or more kinds of things.

[0076] To improve battery safety, in addition to enhancing the thermal safety of the materials themselves, optimizations are being made to the electrode assembly design, such as the use of composite current collectors. Composite current collectors typically consist of an organic support layer (or insulating layer) between two conductive layers (e.g., a metal layer). This improves battery safety and prevents thermal runaway caused by short circuits between the positive and negative electrodes. However, to avoid sacrificing battery energy density and to reduce production costs, current technologies typically reduce the thickness of the conductive layer.

[0077] When the electrolyte contains fluorine-containing sulfonimide salt or fluorine-containing sulfonic acid salt, the electrolyte can corrode the conductive layer (e.g., which can be an aluminum foil). When the conductive layer is thick, the corrosion of the electrolyte is not enough to significantly affect the performance of the battery. However, the inventors of the present application found in the research process that when the thickness of the conductive layer is reduced, the slight corrosion of the electrolyte can significantly affect the performance of the battery. At this time, the fluorine-containing sulfonimide salt or fluorine-containing sulfonic acid salt in the electrolyte can undergo an oxidation reaction at the positive electrode, and the oxidation product can combine with the metal (e.g., aluminum) in the conductive layer, and the combined product can further dissolve into the electrolyte, thereby leaving corrosion pits on the surface of the conductive layer, which can cause the positive electrode tab to break, and even seriously threaten the safety performance and service life of the battery.

[0078] Battery

[0079] In view of the above problems, the embodiments of the present application provide a battery, which includes a positive electrode tab, a negative electrode tab, a separator, and an electrolyte. The present application does not have special restrictions on the type of battery, for example, the battery can be a lithium ion battery, a sodium ion battery, etc., and in particular, the battery can be a lithium ion secondary battery.

[0080] The battery mentioned in the embodiments or embodiments of the present application refers to a single physical module including one or more battery monomers to provide higher voltage and capacity. For example, the battery mentioned in the present application can include a battery monomer, a battery module, or a battery pack, etc. The battery monomer is the smallest unit that makes up the battery, which can realize the function of charging and discharging by itself. The present application does not have special restrictions on the shape of the battery monomer, which can be cylindrical, square or any other shape. For example, Figure 1 is a battery monomer 5 of a square structure as an example.

[0081] In some embodiments, the battery monomer includes an electrode assembly, and the monomer battery can also include an outer package. The electrode assembly can be made of a positive electrode tab, a negative electrode tab, a separator, etc. by a winding process and / or a stacking process, and the outer package can be used to package the above-mentioned electrode assembly and electrolyte. The outer package can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package can also be a soft package, such as a bag-type soft package. The material of the soft package can be plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0082] In some embodiments, as Figure 2As shown, the outer package can include a housing 51 and a cover plate 53. The housing 51 can include a bottom plate and side plates connected to the bottom plate, which enclose a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 is used to cover the opening to close the receiving cavity. The electrode assembly 52 is packaged in the receiving cavity. The number of electrode assemblies 52 contained in the battery cell 5 can be one or more, which can be adjusted according to requirements.

[0083] In some embodiments of the present application, the battery cell can be assembled into a battery module, and the number of battery cells contained in the battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module. Figure 3 is a schematic diagram of a battery module 4 as an example. As shown, Figure 3 In the battery module 4, a plurality of battery cells 5 can be arranged in sequence along the length direction of the battery module 4. Of course, other arbitrary arrangements can also be used. Further, the plurality of battery cells 5 can be fixed by fasteners.

[0084] Optionally, the battery module 4 can also include a housing having a receiving space, and the plurality of battery cells 5 are received in the receiving space.

[0085] In some embodiments, the above-mentioned battery module can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack. Figure 4 and Figure 5 is a schematic diagram of a battery pack 1 as an example. As shown, Figure 4 and Figure 5 As shown, the battery pack 1 can include a battery box and a plurality of battery modules 4 arranged in the battery box. The battery box includes an upper box body 2 and a lower box body 3, and the upper box body 2 is used to cover the lower box body 3 and form a closed space for receiving the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0086] [Electrolyte]

[0087] The electrolyte includes a solvent and a solute, the solute is an ionic salt formed by a cation and an anion, the cation includes one or more selected from alkali metal cations and alkaline earth metal cations, the anion includes a first anion and a second anion, the first anion includes a hexafluorophosphate anion, and the second anion includes one or more selected from a formula 1 anion (containing fluorosulfonylimide anion) and a formula 2 anion (containing fluorosulfonate anion), R1, R2, R3 independently represent a fluorine atom or a C1-C5 fluorine-containing alkyl group, and R1, R2 can also be bonded into a ring.

[0088]

[0089]

[0090] The most widely used non-aqueous electrolyte system in current commercial applications is a mixture of hexafluorophosphate and carbonate, but hexafluorophosphate has poor thermal stability at high temperatures and will decompose to generate PF5 at high temperatures. PF5 has strong Lewis acidity and will react with the lone pair of electrons on the oxygen atom in the solvent molecule to cause decomposition of the solvent. In addition, PF5 has high sensitivity to trace amounts of water in the non-aqueous electrolyte and will produce HF when it comes into contact with water. Fluorosulfonylimide salts and fluorosulfonate salts have the advantages of high thermal stability and insensitivity to water, and the combination of hexafluorophosphate and fluorosulfonylimide salts or fluorosulfonate salts can improve the thermal stability and cycle performance of the battery.

[0091] In the present application, "fluorine-containing alkyl" refers to a group in which at least one hydrogen atom in the alkyl group is replaced by a fluorine atom, which can be a partially fluorinated alkyl group or a perfluoroalkyl group.

[0092] In some embodiments, optionally, R1, R2, R3 each independently represents a fluorine atom, a trifluoromethyl group, a pentafluoroethyl group, a heptafluoropropyl group or a nonafluorobutyl group.

[0093] In some embodiments, optionally, the second anion comprises one or more selected from the group consisting of difluorosulfonylimide anion, bis(trifluoromethylsulfonyl)imide anion, bis(pentafluoroethylsulfonyl)imide anion, bis(nonafluorobutylsulfonyl)imide anion, (trifluoromethylsulfonyl)(nonafluorobutylsulfonyl)imide anion, (fluorosulfonyl)(trifluoromethylsulfonyl)imide anion, perfluoropropanedisulfonylimide anion, fluorosulfonate anion and trifluoromethylsulfonate anion.

[0094] In some embodiments, optionally, R1 and R2 are the same.

[0095] In the present application, the cation comprises one or more selected from the group consisting of alkali metal cations and alkaline earth metal cations. Optionally, the alkali metal cation comprises one or more selected from the group consisting of lithium ion, sodium ion and potassium ion. Optionally, the alkaline earth metal cation comprises one or more selected from the group consisting of magnesium ion, calcium ion or a combination thereof.

[0096] In some embodiments, optionally, the cation comprises one or more selected from the group consisting of lithium ion, sodium ion and potassium ion, and more optionally comprises lithium ion, sodium ion or a combination thereof.

[0097] In some embodiments, the electrolyte further comprises a third anion, wherein the third anion comprises one or more selected from the group consisting of tetrafluoroborate anion (BF4 - ), difluoro(oxalato)borate anion (DFOB -one or more of bisoxalate borate anion (BOB - ), difluorophosphate anion (PO2F2 - ), difluorodioxalate phosphate anion (DFOP - ), and tetrafluorooxalate phosphate anion (TFOP - ). These anions help form a protective film with excellent performance on the surface of the positive electrode and / or the negative electrode, thereby further improving at least one of the cycle performance, rate capability, storage performance, and the like of the battery.

[0098] The kind of the solvent is not specifically limited in the present application, and can be selected according to actual needs. In some embodiments, the solvent can include one or more selected from ethylene carbonate (EC), propylene carbonate (PC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), diethyl sulfone (ESE), fluoroethylene carbonate (FEC), vinyl carbonate (VC), vinyl sulfate (DTD), and 1,3-propane sultone (PS).

[0099] In some embodiments, the electrolyte can also optionally include an additive. For example, the additive can include a negative electrode film-forming additive, can also include a positive electrode film-forming additive, and can also include an additive capable of improving certain performance of the battery, such as an additive capable of improving overcharge performance of the battery, an additive capable of improving high-temperature performance of the battery, an additive capable of improving low-temperature power performance of the battery, and the like.

[0100] In the present application, each component in the electrolyte and its specific content can be determined according to methods known in the art. For example, it can be determined by gas chromatography-mass spectrometry (GC-MS), ion chromatography (IC), liquid chromatography (LC), nuclear magnetic resonance spectroscopy (NMR), and inductively coupled plasma optical emission spectrometry (ICP-OES).

[0101] [Positive electrode tab]

[0102] The positive electrode tab includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector. For example, the positive electrode current collector has two surfaces opposite in the thickness direction of itself, and the positive electrode active material layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.

[0103] In some embodiments, the positive electrode current collector comprises an electrically conductive layer.

[0104] In some embodiments, the positive electrode current collector can only consist of an electrically conductive layer, or, in some embodiments, the positive electrode current collector can comprise an organic support layer in addition to the electrically conductive layer, the electrically conductive layer being disposed on at least one surface of the organic support layer, and the electrically conductive layer also being disposed between the organic support layer and the positive electrode active material layer. For example, the organic support layer has two surfaces opposite in the thickness direction of the organic support layer, and the electrically conductive layer is disposed on either one or both of the two opposite surfaces of the organic support layer to form a composite current collector. In this way, the safety performance of the battery can be further improved, and the problem of thermal runaway caused by short circuit between the positive electrode and the negative electrode can be avoided.

[0105] When the positive electrode current collector only consists of an electrically conductive layer, the thickness of the electrically conductive layer is reduced, the cross-sectional area is reduced, and the resistance is increased, thereby also playing a role in improving the safety performance of the battery, and at the same time, the energy density of the battery can also be improved. In addition, after the thickness of the electrically conductive layer is reduced, the flexibility is better, and thus the risk of positive electrode tab breakage (such as winding breakage) that can occur during the preparation of the battery can also be reduced. However, at this time, the electronic conduction properties of the positive electrode current collector are poor, the polarization of the battery is easily increased, which is not conducive to the cycle performance and rate performance of the battery, and at the same time, the improvement effect on the safety performance of the battery is weak.

[0106] In some embodiments, the positive electrode current collector comprises an organic support layer and an electrically conductive layer disposed on at least one surface of the organic support layer, and the electrically conductive layer is disposed between the organic support layer and the positive electrode active material layer. In this way, the safety performance of the battery can be significantly improved.

[0107] In the present application, the electrically conductive layer can be directly disposed on at least one surface of the organic support layer, or indirectly disposed on at least one surface of the organic support layer, for example, other layers can also be disposed between the electrically conductive layer and the organic support layer.

[0108] In some embodiments, the thickness of the electrically conductive layer is H1 μm, the concentration of the first anion in the electrolyte is C1 mol / L, the concentration of the second anion is C2 mol / L, and the battery satisfies 0.2×(C2 / C1)≤H1≤(C2 / C1)+3.

[0109] Compared with the first anion, the second anion (fluorine-containing sulfimide radical anion and / or fluorine-containing sulfonate radical anion) in the electrolyte has the advantages of high thermal stability and insensitivity to water, can improve the ion dissociation degree of the electrolyte, improve the ionic conductivity of the electrolyte, and further improve the cycle performance of the battery. However, during the charging process, the second anion will undergo an oxidation reaction at the positive electrode, and the oxidation product will combine with the metal (such as aluminum) in the conductive layer, and the combined product will further dissolve into the electrolyte, thereby causing corrosion of the conductive layer.

[0110] In particular, when the positive electrode current collector only uses a relatively thin conductive layer, or the positive electrode current collector uses a composite current collector formed by a relatively thin conductive layer and an organic support layer, since the conductive layer is thinner in the thickness direction than the conventional positive electrode current collector (for example, the thickness is about 12 μm-20 μm), its ability to withstand electrolyte corrosion is weaker, thereby causing the influence of positive electrode current collector corrosion on the safety performance and electrochemical performance of the battery to be more significant, for example, corrosion pits can be formed on the surface of the conductive layer of the positive electrode current collector, thereby causing problems such as shortening of the service life of the battery and significant reduction in safety performance. The decomposition product (such as fluorine-containing lithium salt) of the first anion (or hexafluorophosphate) can be deposited on the surface of the conductive layer of the positive electrode current collector, thereby inhibiting the corrosion of the conductive layer by the second anion and playing a protective role for the conductive layer, but its protective effect on the conductive layer is limited and is not sufficient to compensate for the corrosion of the conductive layer by the second anion.

[0111] Therefore, in the design of the prior art, when the electrolyte does not contain the second anion, the thermal stability of the electrolyte is poor, resulting in suboptimal cycle performance of the battery; when the electrolyte contains the second anion, it will corrode the conductive layer, especially having a serious impact on a relatively thin conductive layer, for example, corrosion pits can be formed on the surface of the relatively thin conductive layer, thereby causing problems such as shortening of the service life of the battery and significant reduction in safety performance. However, some relatively thin conductive layers are currently required to be used alone as the positive electrode current collector, or a composite current collector formed by a relatively thin conductive layer and an organic support layer, etc., in order to increase the safety performance of the battery.

[0112] The inventors of the present application have surprisingly found through a large number of experiments that by adjusting the relationship between the thickness H1 μm of the conductive layer, the concentration C1 mol / L of the first anion and the concentration C2 mol / L of the second anion to satisfy 0.2×(C2 / C1)≤H1≤(C2 / C1)+3, the influence of corrosion of the conductive layer on the safety performance and electrochemical performance of the battery can be reduced, thereby enabling the battery to have good electrochemical performance while improving the safety performance of the battery, for example, the battery can have a longer service life.

[0113] In some embodiments, optionally, 0.2 x (C2 / C1) + 0.2 < H1 < (C2 / C1) + 2. Thereby, the influence of the corrosion of the conductive layer on the safety performance and electrochemical performance of the battery can be further reduced.

[0114] The first anion helps to increase the ionic conductivity of the electrolyte, accelerate ion transmission, and improve the capacity performance of the battery. In some embodiments, the concentration of the first anion in the electrolyte is C1 mol / L, and optionally, 0.1 < C1 < 1. For example, C1 can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, or any range derived from any of these values.

[0115] The second anion can increase the ionic dissociation degree of the electrolyte, reduce the viscosity of the electrolyte, and improve the ionic conductivity of the electrolyte. In addition, the second anion has good high-temperature resistance and is not prone to hydrolysis, thereby improving the cycle performance of the battery. In some embodiments, the concentration of the second anion in the electrolyte is C2 mol / L, and optionally, 0.1 < C2 < 1.5. For example, C2 can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, or any range derived from any of these values. More optionally, 0.5 < C2 < 1.5.

[0116] In some embodiments, optionally, 0.6 < C1 + C2 < 2.5. For example, C1 + C2 can be 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, or any range derived from any of these values. More optionally, 0.6 < C1 + C2 < 2.0.

[0117] In some embodiments, optionally, 0.1 < C2 / C1 < 5. For example, C2 / C1 can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, or any range derived from any of these values. More optionally, 0.5 < C2 / C1 < 5, 1 < C2 / C1 < 5.

[0118] In some embodiments, optionally, the electrolyte satisfies both 0.6 < C1 + C2 < 2.5 and 0.1 < C2 / C1 < 5, and more optionally, the electrolyte satisfies both 0.6 < C1 + C2 < 2.0 and 0.5 < C2 / C1 < 5.

[0119] The inventors of the present application found through a large number of experiments that when the concentration of the first anion and the concentration of the second anion satisfy 0.6≤C1+C2≤2.5 and / or 0.1≤C2 / C1≤5, the corrosion of the conductive layer can be inhibited to some extent, the safety performance of the battery can be improved, and the battery can also maintain excellent cycle performance.

[0120] In some embodiments, the conductive layer can include one or more selected from metal materials, optionally one or more selected from aluminum, silver, nickel, titanium, stainless steel, aluminum alloy, silver alloy, nickel alloy, and titanium alloy, and more optionally aluminum or aluminum alloy. Aluminum has good electrical conductivity and flexibility, is convenient for electron conduction and processing, and fresh aluminum foil is easy to be oxidized in air, thereby a protective film can be formed on the surface to block the corrosion of external moisture and air on aluminum, so that the aluminum foil or aluminum alloy foil is more stable in thermodynamic performance.

[0121] In some embodiments, the organic support layer can include one or more of high molecular materials and high molecular-based composite materials.

[0122] In some embodiments, the high molecular material includes one or more selected from polyolefins, polyacetylenes, polyesters, polycarbonates, polyacrylates, polyamides, polyimides, polyethers, polyalcohols, polysulfones, polythionyls, polysaccharide polymers, amino acid polymers, aromatic ring polymers, aromatic heterocyclic polymers, epoxy resins, phenolic resins, polyurethanes, thermoplastic elastomers, rubbers, derivatives of the above materials, crosslinked products of the above materials, and copolymers of the above materials.

[0123] Optionally, the high molecular material includes one or more selected from polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyacetylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polycarbonate (PC), polymethyl methacrylate (PMMA), polycaprolactam (PA6), poly(hexamethylene) adipamide (PA66), poly(p-phenylene terephthalamide) (PPTA), polyoxymethylene (POM), polyphenylene oxide (PPO), polyphenylene sulfide (PPS), polyethylene glycol (PEG), polyvinyl alcohol (PVA), poly-4-hydroxybenzoic acid, poly-2-hydroxy-6-naphthoic acid, polyaniline (PAN), polypyrrole (PPy), polythiophene (PT), polybenzene, polystyrene sulfonate sodium (PSS), cellulose, starch, silicone rubber, acrylonitrile-butadiene-styrene copolymer (ABS), derivatives of the above materials, crosslinked products of the above materials, and copolymers of the above materials.

[0124] In some embodiments, the high-molecular-based composite material comprises the high-molecular material and an additive, and the additive comprises one or more selected from metal materials and inorganic non-metal materials. The application does not have specific limitations on the types of metal materials and inorganic non-metal materials, which can be selected according to actual needs.

[0125] In some embodiments, optionally, the thickness H1 of the conductive layer satisfies 0.2≤H1≤8. For example, H1 can be 0.2, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8 or any range consisting of any of the above values. More optionally, 1≤H1≤5. In this way, the battery can have good electrochemical performance while improving the safety performance of the battery, for example, the battery can have a longer service life. And it can effectively avoid the following situations: when the conductive layer is too thin, on the one hand, it is not conducive to production and preparation, and on the other hand, there is a risk of being crushed during cold pressing; when the conductive layer is too thick, it may not effectively improve the safety performance of the battery.

[0126] The positive current collector can only consist of the conductive layer, or the positive current collector can comprise an organic support layer in addition to the conductive layer, and the conductive layer is arranged on at least one surface of the organic support layer. In some embodiments, the conductive layer is arranged on one surface of the organic support layer. In some embodiments, the conductive layer is arranged on both surfaces of the organic support layer. It should be noted that the thickness parameter of the conductive layer refers to the thickness parameter of the conductive layer on one side of the organic support layer, or when the positive current collector only consists of the conductive layer, the thickness parameter of the conductive layer is the thickness parameter of the positive current collector. When the conductive layer is arranged on both sides of the organic support layer, the thickness of the conductive layer on both sides can be the same or different; the materials of the conductive layer on both sides can be the same or different. In addition, when the conductive layer is arranged on both sides of the organic support layer, the parameters (such as thickness, material, etc.) of the conductive layer on any one side meet the application, which is considered to fall within the protection scope of the application.

[0127] In some embodiments, optionally, the thickness H1 of the conductive layer and the thickness H2 of the organic support layer satisfy 0.1≤H1 / H2≤1. For example, H1 / H2 can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, or any range derived from any of these values. More optionally, 0.1≤H1 / H2≤0.8, 0.2≤H1 / H2≤0.6. In this way, the battery can have good electrochemical performance, for example, the battery can have a longer service life, while improving the safety performance of the battery. And it can effectively avoid the following situations: when H1 / H2 is too small, there is a risk that the composite current collector will be crushed during the cold pressing process; when H1 / H2 is too large, the safety performance of the battery may not be effectively improved.

[0128] In some embodiments, optionally, the thickness H2 of the organic support layer satisfies 1≤H2≤10. For example, H2 can be 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, or any range derived from any of these values. Optionally, 4≤H2≤7. In this way, the battery can have high energy density, while improving the safety performance of the battery.

[0129] In some embodiments, optionally, the total thickness H0 of the positive electrode current collector satisfies 5≤H0≤15. For example, H0 can be 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, or any range derived from any of these values. More optionally, 9≤H0≤15. In this application, the total thickness of the positive electrode current collector refers to the sum of the thicknesses of the organic support layer and the conductive layers on both sides of the organic support layer.

[0130] The inventors of the present application have also found that the fracture elongation S0 of the positive electrode current collector is related to the total thickness H0 of the positive electrode current collector, the concentration C1 of the first anion, and the concentration C2 of the second anion, when C1 / C2 is larger, H0 is larger, and the fracture elongation S0 of the positive electrode current collector is larger.

[0131] The fracture elongation of the positive electrode current collector refers to the rate of change of the length of the positive electrode current collector when it is stretched at the time of fracture. By comparing the normal positive electrode current collector and the corroded positive electrode current collector, it can be found that when the stretching force is the same, the corroded positive electrode current collector will break when the stretched length is small due to its own defects, so the fracture elongation is small. In addition to being related to whether the positive electrode current collector is corroded, the fracture elongation of the positive electrode current collector is also related to its own thickness. The thicker the positive electrode current collector, the greater the fracture elongation. When the fracture elongation of the positive electrode current collector in the battery is small, it indicates that under the same force, the positive electrode sheet is more likely to break. After the positive electrode sheet breaks, the positive electrode active material on the positive electrode sheet can no longer be used, thereby causing the capacity of the battery to decrease significantly and the cycle performance to decline significantly. In addition, the broken positive electrode sheet has conductivity, and when it comes into contact with the negative electrode sheet, it can directly cause a short circuit in the battery, posing a safety hazard and affecting the safety performance of the battery.

[0132] The inventors of the present application also unexpectedly found during research that when the battery also satisfies 5S0–(H0 / 10)≤C1 / C2≤100S0+(H0 / 9), the influence of corrosion of the conductive layer on the safety performance and electrochemical performance of the battery can be further reduced, thereby enabling the battery to have better safety performance and electrochemical cycle performance.

[0133] In some embodiments, optionally, the fracture elongation S0 of the positive electrode current collector satisfies 2%≤S0≤3.5%. For example, S0 can be 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5% or any range formed by any of the above values.

[0134] In some embodiments, the positive electrode active material layer comprises a positive electrode active material.

[0135] When the battery of the present application is a lithium ion battery, the positive electrode active material can include, but is not limited to, one or more of a lithium-containing transition metal oxide, a lithium-containing phosphate and a modified compound of each thereof. Examples of the lithium-containing transition metal oxide can include, but are not limited to, one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide and a modified compound of each thereof. Examples of the lithium-containing phosphate can include, but are not limited to, one or more of lithium iron phosphate, a composite of lithium iron phosphate and carbon, lithium manganese phosphate, a composite of lithium manganese phosphate and carbon, lithium manganese iron phosphate, a composite of lithium manganese iron phosphate and carbon and a modified compound of each thereof.

[0136] In some embodiments, in order to further improve the energy density of the battery, the positive electrode active material for a lithium ion battery can include a compound represented by the general formula LiNix Co y M z O 2-p A p LiNiO2, LiMn2O4, Li2MnO3, LiMnO2, LiFePO4, and LiMnPO4. In some embodiments, the cathode active material can include one or more of LiCoO2, LiNiO2, LiMn2O4, Li2MnO3, LiMnO2, LiFePO4, and LiMnPO4. x Co y M z O 2-p A p In some embodiments, M includes one or more selected from the group consisting of Mn, Al, Mg, Cu, Zn, Zr, Fe, Sn, B, Ga, Cr, Sr, V, and Ti, A includes one or more selected from the group consisting of N, F, S, and Cl, 0≤x≤1, 0≤y≤1, 0≤z≤1, x+y+z=1, 0≤p≤1. In some embodiments, Q includes one or more selected from the group consisting of Ni, Co, Mn, Fe, Ti, Cr, and Zr, 0

[0137] As an example, the cathode active material for a lithium ion battery can include LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM811), LiNi 0.85 Co 0.15 Al 0.05 O2, LiMn2O4, aLi2MnO3·(1-a)LiMnO2, LiFePO4, and LiMnPO4.

[0138] When the battery of the present application is a sodium ion battery, the cathode active material can include, but is not limited to, one or more of sodium-containing transition metal oxides, polyanion materials (such as phosphates, fluorophosphates, pyrophosphates, sulfates, etc.), and Prussian blue type materials.

[0139] As an example, the cathode active material for a sodium ion battery can include NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, NaNi 1 / 2 Ti1 / 2 O2, NaNi 1 / 2 Mn 1 / 2 O2, Na 2 / 3 Fe 1 / 3 Mn 2 / 3 O2, NaNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, NaFePO4, NaMnPO4, NaCoPO4, Prussian blue-based materials, materials of general formula X p M’ q (PO4) r O x Y 3-x . In the general formula X p M’ q (PO4) r O x Y 3-x , 0 < p < 4, 0 < q < 2, 1 < r < 3, 0 < x < 2, X includes one or more selected from H + , Li + , Na + , K + , and NH4 + , M’ is a transition metal cation, optionally including one or more selected from V, Ti, Mn, Fe, Co, Ni, Cu, and Zn, and Y is a halide anion, optionally including one or more selected from F, Cl, and Br.

[0140] In the present application, the modified compound of each of the above positive electrode active materials can be a doping modification and / or a surface coating modification to the positive electrode active material.

[0141] In some embodiments, the positive electrode active material layer can further include a positive electrode conductive agent. The present application does not have a particular limitation on the type of the positive electrode conductive agent, and as an example, the positive electrode conductive agent includes one or more of super P, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0142] In some embodiments, the positive electrode active material layer can further include a positive electrode binder. The present application does not have a particular limitation on the type of the positive electrode binder, and as an example, the positive electrode binder can include one or more of polyvinylidene fluoride, polytetrafluoroethylene, a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylic ester-based resin.

[0143] The positive electrode active material layer is typically formed by coating a positive electrode slurry on a positive electrode current collector, drying, and cold-pressing. The positive electrode slurry is typically formed by dispersing a positive electrode active material, an optional conductive agent, an optional binder, and any other components in a solvent and stirring them uniformly. The solvent can be N-methylpyrrolidone, but is not limited thereto.

[0144] FIG. 1 is a schematic view of a positive electrode tab according to an embodiment of the present application.

[0145] Figure 6 FIG. 1 is a schematic view of a positive electrode tab according to an embodiment of the present application. Figure 6 As shown in FIG. 1, the positive electrode tab 10 includes a positive electrode current collector 101 and a positive electrode active material layer 102 disposed on both surfaces of the positive electrode current collector 101. The positive electrode current collector 101 includes an organic support layer 1012 and a conductive layer 1011 disposed on both surfaces of the organic support layer 1012. The conductive layer 1011 is disposed between the organic support layer 1012 and the positive electrode active material layer 102.

[0146] Figure 7 FIG. 2 is a schematic view of another embodiment of the positive electrode tab 10 according to the present application. Figure 7 As shown in FIG. 2, the positive electrode tab 10 includes a positive electrode current collector 101 and a positive electrode active material layer 102 disposed on one surface of the positive electrode current collector 101. The positive electrode current collector 101 includes an organic support layer 1012 and a conductive layer 1011 disposed on one surface of the organic support layer 1012. The conductive layer 1011 is disposed between the organic support layer 1012 and the positive electrode active material layer 102.

[0147] [Negative electrode tab]

[0148] The negative electrode tab includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector. For example, the negative electrode current collector has two surfaces opposite in the thickness direction thereof, and the negative electrode active material layer is disposed on either one or both of the two opposite surfaces of the negative electrode current collector.

[0149] In some embodiments, the negative electrode active material layer includes a negative electrode active material. The negative electrode active material can be any known in the art for use in a battery. As an example, the negative electrode active material can include, but is not limited to, one or more of natural graphite, artificial graphite, meso-carbon microbead, soft carbon, hard carbon, silicon-based material, tin-based material, lithium titanate, and lithium-aluminum alloy. The silicon-based material can include one or more selected from elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy material. The tin-based material can include one or more selected from elemental tin, tin oxide (e.g., SnO, SnO2), and tin alloy material (e.g., Li-Sn alloy, Li-Sn-O alloy).

[0150] In some embodiments, the negative active material layer can further include a negative conductive agent. The present application does not have a particular limitation on the kind of the negative conductive agent, which may, for example, include one or more selected from super P, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0151] In some embodiments, the negative active material layer can further include a negative binder. The present application does not have a particular limitation on the kind of the negative binder, which may, for example, include one or more selected from styrene butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-based acrylic resin (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0152] In some embodiments, the negative active material layer can further include other auxiliary agents. For example, the other auxiliary agents can include a thickening agent, such as sodium carboxymethyl cellulose (CMC), PTC thermistor material, etc.

[0153] In some embodiments, the negative current collector can be a metal foil or a composite current collector. As an example of the metal foil, a copper foil can be used. The composite current collector can include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material can include one or more of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer can include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0154] The negative active material layer is generally formed by coating a negative slurry on a negative current collector, drying, and cold-pressing. The negative slurry is generally formed by dispersing a negative active material, an optional conductive agent, an optional binder, and an optional auxiliary agent in a solvent and stirring uniformly. The solvent can be N-methyl pyrrolidone or deionized water, but is not limited thereto.

[0155] The negative electrode sheet does not exclude other additional functional layers other than the negative active material layer. For example, in some embodiments, the negative electrode sheet described in the present application further includes a conductive primer layer (e.g., composed of a conductive agent and a binder) disposed on the surface of the negative current collector, sandwiched between the negative current collector and the negative active material layer; in some embodiments, the negative electrode sheet described in the present application further includes a protective layer covering the surface of the negative active material layer.

[0156] [Separator]

[0157] The separator is located between the positive electrode tab and the negative electrode tab, mainly to prevent the positive electrode and the negative electrode from short-circuiting, while allowing active ions to pass through. The type of the separator is not particularly limited in the present application, and any known porous structure separator with good chemical stability and mechanical stability can be selected.

[0158] In some embodiments, the material of the separator can include one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of the layers can be the same or different.

[0159] Preparation method

[0160] The present application also provides a method for preparing a battery, comprising the following steps 1 and step 2.

[0161] Step 1, assembling a positive electrode tab, a separator, a negative electrode tab, and an electrolyte into a battery.

[0162] The positive electrode tab includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector, and the positive electrode current collector includes a conductive layer.

[0163] The electrolyte includes a solvent and a solute, and the solute is an ionic salt formed by a cation and an anion, the cation includes one or more selected from alkali metal cations and alkaline earth metal cations, and optionally includes one or more selected from lithium ions, sodium ions, and potassium ions, and the anion includes a first anion and a second anion, the first anion includes a hexafluorophosphate anion, and the second anion includes one or more selected from anions represented by Formula 1 and anions represented by Formula 2, R1, R2, and R3 each independently represent a fluorine atom or a C1-C5 fluorine-containing alkyl group, and R1 and R2 can also be bonded to form a ring.

[0164] The thickness of the conductive layer is H1 μm, and the concentration of the first anion in the electrolyte is C1 mol / L and the concentration of the second anion is C2 mol / L.

[0165]

[0166] Step 2, selecting a battery that satisfies 0.2×(C2 / C1)≤H1≤(C2 / C1)+3, and optionally satisfies 0.2×(C2 / C1)+0.2≤H1≤(C2 / C1)+2, from the battery obtained in step 1.

[0167] In some embodiments, in step 1, the positive electrode current collector further comprises an organic support layer, the conductive layer is provided on at least one surface of the organic support layer, and the conductive layer is also provided between the organic support layer and the positive electrode active material layer, the thickness of the organic support layer is H2μm, the total thickness of the positive electrode current collector is H0μm, and the breaking elongation of the positive electrode current collector is S0.

[0168] In some embodiments, the method further comprises: step 3, screening the battery obtained in step 2 to obtain a battery satisfying at least one of conditions (1) to (9) below,

[0169] (1) 0.2≤H1≤8,

[0170] (2) 1≤H1≤5,

[0171] (3) 0.1≤C1≤1,

[0172] (4) 0.1≤C2≤1.5,

[0173] (5) 0.5≤C2≤1.5,

[0174] (6) 0.6≤C1+C2≤2.5,

[0175] (7) 0.6≤C1+C2≤2.0,

[0176] (8) 0.1≤C2 / C1≤5,

[0177] (9) 0.5≤C2 / C1≤5.

[0178] In some embodiments, the method further comprises: step 4, screening the battery obtained in step 2 or step 3 to obtain a battery satisfying at least one of conditions (1) to (8) below,

[0179] (1) 5S0–(H0 / 10)≤C1 / C2≤100S0+(H0 / 9),

[0180] (2) 0.1≤H1 / H2≤1,

[0181] (3) 0.2≤H1 / H2≤0.6,

[0182] (4) 1≤H2≤10,

[0183] (5) 4≤H2≤7,

[0184] (6) 5≤H0≤15,

[0185] (7) 9≤H0≤15,

[0186] (8) 2%≤S0≤3.5%.

[0187] The battery obtained by the preparation method of the present application has high safety performance and good electrochemical performance.

[0188] In some embodiments, in step 1, the preparation method of the battery is known. As an example, the positive electrode sheet, the separator film, and the negative electrode sheet can be wound and / or laminated to form an electrode assembly, the electrode assembly can be placed in an outer package, and the battery monomer can be obtained after drying, injecting electrolyte, vacuum packaging, standing, formation, shaping, and other processes. A plurality of battery monomers can further be connected in series or in parallel or in a hybrid manner to form a battery module. A plurality of battery modules can further be connected in series or in parallel or in a hybrid manner to form a battery pack. In some embodiments, a plurality of battery monomers can also be directly connected to form a battery pack.

[0189] Electric device

[0190] The present application also provides a power utilization device comprising the battery of the present application. The battery can be used as a power source of the power utilization device, or as an energy storage unit of the power utilization device. The power utilization device can be, but is not limited to, a mobile device (such as a mobile phone, a tablet computer, a notebook computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, etc.

[0191] The specific type of the battery (such as a battery monomer, a battery module, or a battery pack) can be selected according to the use requirements of the power utilization device.

[0192] Figure 8 is a schematic diagram of a power utilization device as an example. The power utilization device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the requirements of high power and high energy density of the power utilization device, a battery pack or a battery module can be used as a power source.

[0193] The power utilization device as another example can be a mobile phone, a tablet computer, a notebook computer, etc. The power utilization device usually requires thinning, and a battery monomer can be used as a power source.

[0194] Embodiment

[0195] The present application is described in more detail by the following examples, which are merely illustrative and not limiting the scope of the present application, since various modifications and changes in the examples obviously can be made by those skilled in the art. Unless otherwise indicated, all parts, percentages, and ratios reported in the following examples are on a mass basis, and all reagents used in the examples are commercially available or synthesized according to conventional methods and used as received without further purification, and the instruments used in the examples are commercially available.

[0196] The batteries of Examples 1-17 and Comparative Examples 1-3 were prepared as follows.

[0197] Preparation of electrolyte

[0198] In an argon-filled glove box (water content < 10 ppm, oxygen content < 1 ppm), ethylene carbonate (EC) and methyl ethyl carbonate (EMC) were mixed in a mass ratio of 30:70 to obtain an organic solvent, then 2 wt% of vinylene carbonate (VC) was added to the organic solvent, and then a fully dried lithium salt was added to the organic solvent to prepare an electrolyte. The types and concentrations of the lithium salts are shown in Table 1.

[0199] Preparation of positive electrode sheet

[0200] The aluminum foil was placed in a mechanical roller and rolled into a predetermined thickness of a conductive layer by applying a pressure of 20-40 tons; then a mixed solution of polyvinylidene fluoride (PVDF) and NMP was coated on the surface of an organic support layer of surface-cleaned polyethylene terephthalate (PET); and finally the conductive layer of the predetermined thickness was bonded to both surfaces of the organic support layer and dried to obtain a positive current collector. The specific thickness parameters of the conductive layer and the organic support layer are shown in Table 2.

[0201] The positive active material LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM523), a conductive agent carbon black (Super P), and a binder polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 80:10:10 in an appropriate amount of solvent NMP to form a positive electrode slurry with a solid content of 50 wt%; the positive electrode slurry was uniformly coated on the surface of the positive current collector prepared above, and after drying and cold pressing, a positive electrode sheet was obtained.

[0202] Preparation of negative electrode sheet

[0203] The negative active material graphite, the conductive agent carbon black (Super P), the thickening agent sodium carboxymethyl cellulose (CMC) and the binder styrene-butadiene rubber (SBR) are mixed in a proper amount of solvent deionized water in a mass ratio of 80:15:3:2, to form a negative slurry with a solid content of 30wt%; the negative slurry is uniformly coated on the surface of the negative current collector copper foil, and after drying and cold pressing, a negative electrode sheet is obtained.

[0204] Preparation of separator

[0205] A porous polyethylene film with a thickness of 16 μm is used as the separator film.

[0206] Preparation of battery

[0207] The positive electrode sheet, the separator film and the negative electrode sheet are stacked and wound in sequence to obtain an electrode assembly; the electrode assembly is placed in an outer package, and after drying, an electrolyte is injected; after vacuum packaging, standing, formation and shaping processes, a soft-packaged battery is obtained.

[0208] Table 1

[0209]

[0210] Table 2

[0211]

[0212] Test section

[0213] (1) Needle puncture test

[0214] At 25℃, the battery is charged at 1C constant current to 4.2V, and then charged at 4.2V constant voltage to a current less than or equal to 0.05C, and a high-temperature-resistant steel needle with a diameter of 3mm is used to puncture from the center of the large surface of the battery to the battery out of control at a speed of 0.1mm / s, and the state of the battery at thermal runaway is recorded.

[0215] (2) Cycle performance test

[0216] ​The battery was charged at 1C constant current to 4.2V at 25℃, then charged at 4.2V constant voltage until the current was less than or equal to 0.05C, at this time the battery was full, and the charge capacity at this time was recorded, which was the charge capacity of the first cycle; the battery was allowed to stand for 5min, then discharged at 1C constant current to 2.8V, which was one cycle of charge and discharge, and the discharge capacity at this time was recorded, which was the discharge capacity of the first cycle. The battery was subjected to cycle charge and discharge test according to the above method, and the discharge capacity after each cycle was recorded. The capacity retention rate (%) of the battery at 25℃ after 500 cycles = the discharge capacity after 500 cycles / the discharge capacity of the first cycle x 100%. For accuracy, the average value of 5 parallel samples was taken as the test result.

[0217] Table 3

[0218]

[0219] From the test results in Table 3, it can be seen that when the relationship between the thickness H1 of the conductive layer, the concentration C1 of the first anion and the concentration C2 of the second anion satisfies 0.2 x (C2 / C1) ≤ H1 ≤ (C2 / C1) + 3, and optionally satisfies 0.2 x (C2 / C1) + 0.2 ≤ H1 ≤ (C2 / C1) + 2, the safety performance and the cycle performance of the battery can be significantly improved, at this time the probability of the battery catching fire is significantly reduced, and at the same time the adverse effects of the increased corrosion caused by the reduced thickness of the conductive layer on the cycle performance of the battery can also be significantly reduced.

[0220] From the test results of Example 1, Example 11 and Comparative Example 1, it can be seen that when the electrolyte composition is the same, the safety performance and the cycle performance of the battery are significantly affected by the slight corrosion of the conductive layer by the electrolyte, because the conductive layer of Comparative Example 1 is relatively thin.

[0221] From the test results of Example 3, Examples 6-9 and Comparative Example 2, it can be seen that when the electrolyte composition is the same, the safety performance of the battery is poor because the conductive layer of Comparative Example 2 is relatively thick, which does not satisfy 0.2 x (C2 / C1) + 0.2 ≤ H1 ≤ (C2 / C1) + 2, and the conductivity of the positive current collector is relatively strong, even if an organic support layer is used, it cannot effectively prevent the short circuit between the positive electrode and the negative electrode, and thus the safety performance of the battery is poor; in addition, the thickness of the conductive layer of Comparative Example 2 is relatively thick, which is not conducive to heat dissipation during the cycle, at this time there are more side reactions inside the battery, and thus the cycle performance of the battery is also poor.

[0222] The ordinary 12 μm thick aluminum foil was used as the positive current collector in Comparative Example 3, which has small resistance and good conductivity. Thus, short circuit between the positive electrode and the negative electrode easily occurred during the needle-punching test, which resulted in poor safety performance of the battery. Meanwhile, compared with the composite current collector formed by the conductive layer and the organic support layer, the positive current collector using the pure aluminum foil has poor heat preservation performance, which further results in poor kinetics performance of the positive electrode side of the battery. During the charge and discharge, the positive electrode has large resistance for lithium intercalation and deintercalation, which easily causes more side reactions, and thus the battery has poor cycle performance.

[0223] It can also be known from the test results of Examples 1-17 that, when the battery further satisfies 5S0–(H0 / 10)≤C1 / C2≤100S0+(H0 / 9), the safety performance and the cycle performance of the battery are further improved.

[0224] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and embodiments having substantially the same configuration and playing the same role and effect as the technical idea within the scope of the technical solutions of the present application are all included in the technical scope of the present application. In addition, within the scope of the main idea of the present application, various modifications of the embodiments that can be thought of by those skilled in the art, and other ways constructed by combining part of the constituent elements of the embodiments are also included in the scope of the present application.

Claims

1. A battery comprising a positive electrode sheet and an electrolyte, wherein the positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer provided on at least one surface of the positive electrode current collector, the positive electrode current collector comprises an electrically conductive layer, the electrolyte comprises a solvent and a solute, the solute is an ionic salt formed from a cation and an anion, the cation comprises one or more selected from alkali metal cations and alkaline earth metal cations, the anion comprises a first anion and a second anion, the first anion comprises a hexafluorophosphate anion, the second anion comprises one or more selected from anions represented by Formula 1 and anions represented by Formula 2, R1, R2, R3 each independently represent a fluorine atom or a C1-C5 fluorine-containing alkyl group, R1, R2 can also be bonded to form a ring, Formula 1 Formula 2 a thickness of the electrically conductive layer is H1 μm, a concentration of the first anion in the electrolyte is C1 mol / L and a concentration of the second anion is C2 mol / L, 0.2 < C1 ≤ 1, and the battery satisfies 0.2 x (C2 / C1) ≤ H1 ≤ (C2 / C1) + 3; the positive electrode current collector further comprises an organic support layer, the electrically conductive layer is provided on at least one surface of the organic support layer, and the electrically conductive layer is further provided between the organic support layer and the positive electrode active material layer.

2. The battery of claim 1, wherein, the cation comprises one or more selected from lithium ions, sodium ions, and potassium ions.

3. The battery of claim 1, wherein, 0.2 x (C2 / C1) + 0.2 ≤ H1 ≤ (C2 / C1) + 2.

4. The battery according to any one of claims 1 to 3, wherein 0.2 ≤ H1 ≤ 8; and / or, 0.1≤C2≤1.5。 5. The battery according to any one of claims 1 to 3, wherein 1≤H1≤5。 6. The battery of any one of claims 1-3, wherein, 0.5≤C2≤1.5。 7. The battery according to claim 1, wherein 0.6 ≤ C1 + C2 ≤ 2.5; and / or, 0.1 ≤ C2 / C1 ≤ 5.

8. The battery of claim 1, wherein, 0.6 ≤ C1 + C2 ≤ 2.

0.

9. The battery of claim 1, wherein, 0.5 ≤ C2 / C1 ≤ 5.

10. The battery of claim 1, wherein, a thickness of the organic support layer is H2 μm, and the battery satisfies 0.1 ≤ H1 / H2 ≤ 1.

11. The battery of claim 10, wherein, 0.2 ≤ H1 / H2 ≤ 0.

6.

12. The battery of claim 1, wherein, a thickness of the organic support layer is H2 μm, 1 ≤ H2 ≤ 10.

13. The battery of claim 12, wherein, 4≤H2≤7。 14. The battery of claim 1, wherein, a total thickness of the positive electrode current collector is H0 μm, 5 ≤ H0 ≤ 15.

15. The battery of claim 14, wherein, 9≤H0≤15。 16. The battery of claim 1, wherein, a total thickness of the positive electrode current collector is H0 μm, an elongation at break of the positive electrode current collector is S0, and the battery satisfies 5S0 - (H0 / 10) ≤ C1 / C2 ≤ 100S0 + (H0 / 9).

17. The battery of claim 15, wherein, 2%≤S0≤3.5%。 18. The battery of claim 1, wherein, the organic support layer comprises one or more of a high molecular material and a high molecular-based composite material, the high molecular material comprises one or more selected from polyolefins, polyacetylenes, polyesters, polycarbonates, polyacrylates, polyamides, polyimides, polyethers, polyalcohols, polysulfones, polythiazenes, polysaccharide polymers, amino acid polymers, aromatic ring polymers, aromatic heterocyclic polymers, epoxy resins, phenol resins, polyurethanes, thermoplastic elastomers, rubbers, derivatives of the above materials, crosslinked products of the above materials, and copolymers of the above materials. The high polymer-based composite includes the high polymer material and an additive, and the additive includes one or more selected from a metal material and an inorganic non-metal material.

19. The battery of claim 18, wherein, The high polymer material includes one or more selected from polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, polyacetylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polymethyl methacrylate, polycaprolactam, polyhexamethylene adipamide, poly-para-phenyleneterephthalamide, polyformaldehyde, polyphenylene ether, polyphenylene sulfide, polyethylene glycol, polyvinyl alcohol, poly-4-hydroxybenzoic acid, poly-2-hydroxy-6-naphthoic acid, polyaniline, polypyrrole, polythiophene, polyphenyl, polystyrene sulfonate sodium, cellulose, starch, silicone rubber, acrylonitrile-butadiene-styrene copolymer, derivatives of the above-mentioned materials, cross-linked materials of the above-mentioned materials, and copolymers of the above-mentioned materials.

20. The battery of claim 1, wherein, The conductive layer includes a metal material.

21. The battery of claim 1, wherein, The conductive layer includes one or more selected from aluminum, silver, nickel, titanium, stainless steel, aluminum alloy, silver alloy, nickel alloy, and titanium alloy.

22. The battery according to claim 1, wherein, R1, R2, R3 each independently represent a fluorine atom, a trifluoromethyl group, a pentafluoroethyl group, or a heptafluoropropyl group; and / or, R1 and R2 are the same.

23. The battery of claim 1, wherein, The electrolyte further includes a third anion, and the third anion includes one or more selected from a tetrafluoroborate anion, a difluoro oxalate borate anion, a di-oxalate borate anion, a difluorophosphate anion, a difluoro di-oxalate phosphate anion, and a tetrafluoro oxalate phosphate anion.

24. The battery of claim 1, wherein, The battery further includes a negative electrode sheet and a separator, and the separator is located between the positive electrode sheet and the negative electrode sheet.

25. A method for manufacturing a battery, comprising the following steps: Step 1, assembling a positive electrode sheet, a separator, a negative electrode sheet, and an electrolyte into a battery, The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer provided on at least one surface of the positive electrode current collector, and the positive electrode current collector includes a conductive layer, The electrolyte includes a solvent and a solute, and the solute is an ionic salt formed by a cation and an anion, the cation includes one or more selected from an alkali metal cation and an alkaline earth metal cation, and the anion includes a first anion and a second anion, the first anion includes a hexafluorophosphate anion, and the second anion includes one or more selected from an anion represented by Formula 1 and an anion represented by Formula 2, R1, R2, R3 each independently represent a fluorine atom or a C1-C5 fluorine-containing alkyl group, and R1 and R2 can also be bonded into a ring, Formula 1 Formula 2 The thickness of the conductive layer is H1 μm, the concentration of the first anion in the electrolyte is C1 mol / L, the concentration of the second anion is C2 mol / L, and 0.2 < C1 ≤ 1. In step 1, the positive current collector further comprises an organic support layer, the conductive layer is disposed on at least one surface of the organic support layer, and the conductive layer is also disposed between the organic support layer and the positive active material layer, the thickness of the organic support layer is H2 μm, the total thickness of the positive current collector is H0 μm, and the breaking elongation of the positive current collector is S0; Step 2: selecting a battery from the battery obtained in step 1 that satisfies 0.2×(C2 / C1)≤H1≤(C2 / C1) + 3.

26. The method of claim 25, wherein, The cation comprises one or more selected from lithium ion, sodium ion and potassium ion.

27. The method of claim 25, wherein, Step 2: selecting a battery from the battery obtained in step 1 that satisfies 0.2×(C2 / C1) + 0.2≤H1≤(C2 / C1) + 2.

28. The method of claim 25, wherein, The method further comprises: step 3, selecting a battery from the battery obtained in step 2 that satisfies at least one of conditions (1), (3), (5) and (7), （1）0.2≤H1≤8， （3）0.1≤C2≤1.5， (5) 0.6≤C1+C2≤2.5, (7) 0.1≤C2 / C1≤5.

29. The method of claim 25, wherein, The method further comprises: step 3, selecting a battery from the battery obtained in step 2 that satisfies at least one of conditions (2), (4), (6) and (8), （2）1≤H1≤5， （4）0.5≤C2≤1.5， (6) 0.6≤C1+C2≤2.0, (8) 0.5≤C2 / C1≤5.

30. The method of claim 25, wherein, The method further comprises: step 4, selecting a battery from the battery obtained in step 2 or step 3 that satisfies at least one of conditions (1), (2), (4), (6) and (8), (1) 5S0 – (H0 / 10)≤C1 / C2≤100S0 + (H0 / 9), (2) 0.1≤H1 / H2≤1, （4）1≤H2≤10， （6）5≤H0≤15， （8）2%≤S0≤3.5%。 31. The method of claim 25, wherein, The method further comprises: step 4, selecting a battery from the battery obtained in step 2 or step 3 that satisfies at least one of conditions (3), (5) and (7), (3) 0.2≤H1 / H2≤0.6, （5）4≤H2≤7， （7）9≤H0≤15。 32. An electrical device comprising the battery of any one of claims 1-24 or the battery prepared by the method of any one of claims 25-31.

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