Lithium-ion battery

Abstract

In order to solve the problems of the insufficient rate capability, high-temperature performance and low-temperature performance of existing lithium-ion batteries, a lithium-ion battery is provided. The lithium-ion battery comprises a positive electrode, a negative electrode and a non-aqueous electrolyte solution, wherein the negative electrode comprises a negative electrode material layer containing a negative electrode active material, and a negative electrode interface film formed on the surface of the negative electrode material layer, the negative electrode material layer having a specific surface area of 0.5-5 m2 / g and a median particle size of 8-17 μm; the non-aqueous electrolyte solution comprises a non-aqueous organic solvent, a lithium salt and an additive, the additive comprising a lithium salt additive and a compound as represented by structural formula (1): structural formula (1); and the lithium-ion battery satisfies the following condition: 0.5≤Wa / Wb≤10. By means of the intercoordination of the proportions of an organic matter component and an inorganic matter component in the negative electrode interface film of the lithium-ion battery, the interfacial transport channel of lithium ions can be optimized, and optimal high-temperature storage performance is obtained, while the low-temperature performance and the rate capability are improved.

Description

A lithium ion battery TECHNICAL FIELD

[0001] The application belongs to the technical field of energy storage components and specifically relates to a lithium ion battery. BACKGROUND

[0002] Lithium ion batteries (LIBs) have become a mainstream energy storage technology that is ubiquitous in portable electronic devices and electric vehicles (EVs). Despite the widespread application and associated advantages of LIBs, they still face significant challenges in terms of cycle stability, safety, and fast charging capability. These challenges are mainly due to the formation of a solid electrolyte interphase (SEI) layer on the graphite negative electrode. The SEI is formed by the irreversible decomposition of electrolyte components at the negative electrode / electrolyte interface and is a key component for maintaining the electrochemical stability of the negative electrode and preventing excessive electrolyte consumption. However, an undesirable SEI layer can have a negative impact on the graphite negative electrode. This is mainly due to two reasons. First, the SEI may not completely cover the graphite due to poor compatibility of the electrolyte / electrode interface. Second, the components of the SEI may not be stable. Especially in fast charging systems, the negative reaction between the electrolyte and the electrode is intensified at high rates, the electrode terminal interface polarization increases, and the battery produces uneven heat, which poses greater challenges to the negative electrode SEI. However, existing lithium ion batteries do not have specific rules for how to construct a stable, low-impedance, and uniform SEI layer, and there are significant differences between different lithium ion batteries. Therefore, how to construct a high-stability and low-DCIR SEI film is a problem that needs to be solved. SUMMARY

[0003] In view of the problems of insufficient rate performance, high-temperature performance and low-temperature performance of the existing lithium ion battery, the application provides a lithium ion battery.

[0004] The technical scheme adopted by the application to solve the above technical problems is as follows:

[0005] The application provides a lithium ion battery, which comprises a positive electrode, a negative electrode and a non-aqueous electrolyte, the negative electrode comprises a negative electrode material layer comprising a negative electrode active material and a negative electrode interfacial film formed on the surface of the negative electrode material layer, the specific surface area of the negative electrode material layer is 0.5-5 m 2 / g, the median particle size of the negative electrode material layer is 8-17 mu m, the non-aqueous electrolyte comprises a non-aqueous organic solvent, a lithium salt and an additive, the additive comprises a lithium salt type additive and a compound represented by structural formula 1.

[0006] wherein n is 0 or 1, A is selected from C or O, X is selected from R1, R2 are each independently selected from H, R1and R2are not simultaneously selected from H, and at least one of X, R1and R2contains a sulfur atom;

[0007] The ratio of the peak area Wa of the inorganic component with a binding energy of 680-685 eV to the peak area Wb of the organic component with a binding energy of 165-175 eV is 0.5≤Wa / Wb≤10.

[0008] Optionally, the lithium ion battery satisfies the following conditions:

[0009] 0.8≤Wa / Wb≤8.

[0010] Optionally, the mass percentage content of the compound represented by the structural formula 1 is 0.1%-3% based on the total mass of the non-aqueous electrolyte being 100%.

[0011] Optionally, the mass percentage content of the lithium salt type additive is 0.01%-2% based on the total mass of the non-aqueous electrolyte being 100%.

[0012] Optionally, the lithium salt type additive includes one or more of LiODFB (lithium difluoro(oxalato)borate) and LiODFP (lithium difluorophosphate).

[0013] Optionally, the compound represented by the structural formula 1 includes one or more of the following compounds:

[0014] Optionally, the specific surface area of the negative electrode material layer is 1.0-4 m 2 / g, and / or

[0015] The median particle size of the negative electrode material layer is 10-15 μm.

[0016] Optionally, the formation conditions of the lithium ion battery are as follows:

[0017] The formation temperature is 40-50℃, the formation pressure is 2-8 kg / cm 2 , the charging current is 0.05C-0.12C, and the discharging current is 0.1C-0.3C.

[0018] Optionally, the additive further includes at least one of a cyclic sulfate compound, a sulfonic acid lactone compound, a cyclic carbonate compound, a phosphate compound, a borate compound and a nitrile compound.

[0019] Optionally, the cyclic sulfate compound includes at least one of vinyl sulfate, 1,3,2-dioxathiane-2,2-dioxide, and methyl vinyl sulfate; and / or

[0020] The sulfonic acid lactone compound includes at least one of 1,3-propane sulfonic acid lactone, 1,4-butane sulfonic acid lactone, and 1,3-propylene sulfonic acid lactone; and / or

[0021] The cyclic carbonate compound includes at least one of vinylene carbonate, vinyl ethylene carbonate, methylene vinyl carbonate, or a compound represented by structural formula 2:

[0022] In the structural formula 2, R 21 , R 22 , R 23 , R 24 , R 25 , R 26 are each independently selected from one of a hydrogen atom, a halogen atom, and a C1-C5 group; and / or

[0023] The phosphate compound includes at least one of tris(trimethylsilyl)phosphate, tris(triethylsilyl)phosphate, or a compound represented by structural formula 3:

[0024] In the structural formula 3, R 31 , R 32 , R 33 are each independently selected from a C1-C5 saturated hydrocarbon group, a C1-C5 unsaturated hydrocarbon group, a C1-C5 halogenated hydrocarbon group, -Si(C m H 2m+1 )3, m is a natural number of 1 to 3, and at least one of R 31 , R 32 , R 33 is an unsaturated hydrocarbon group; and / or

[0025] The borate compound includes at least one of tris(trimethylsilyl)borate and tris(triethylsilyl)borate; and / or

[0026] The nitrile compound includes at least one of butanedinitrile, pentanedinitrile, hexanetristitnitrile, hexanedinitrile, heptanedinitrile, octanedinitrile, nonanedinitrile, and decanedinitrile.

[0027] The lithium ion battery provided by the application adds the compound shown in structural formula 1 and the lithium salt type additive into the non-aqueous electrolyte, and the compound shown in structural formula 1 and the lithium salt type additive are decomposed together on the surface of the negative electrode material layer to form a negative electrode interface film containing organic components and inorganic components mixed with each other during the formation of the battery, and the inventor finds through a large number of researches that, by adjusting the proportion of the compound shown in structural formula 1 and the lithium salt type additive and controlling the specific surface area of the negative electrode material layer to be 0.5-5 m 2 / g and the median particle size of the negative electrode material layer to be 8-17 μm, and the inorganic component Wa of the negative electrode interface film on the surface of the negative electrode and the organic component Wb of the negative electrode interface film satisfy the condition 0.5≤Wa / Wb≤10, the obtained lithium ion battery can simultaneously have good high-temperature performance, low-temperature performance and high-rate charge-discharge performance, and it is speculated that, under the condition, a thinner, denser and more stable negative electrode interface film is formed, the proportion of the organic component and the inorganic component in the negative electrode interface film is coordinated with each other, the lithium ion interface transmission channel is optimized, the low-temperature performance and the high-rate performance are improved, and the high-temperature storage performance is optimal. DETAILED DESCRIPTION

[0028] In order to make the technical problems, technical solutions and beneficial effects of the present application clearer, the present application will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not used to limit the present application.

[0029] The embodiment of the present application provides a lithium ion battery, which comprises a positive electrode, a negative electrode and a non-aqueous electrolyte, the negative electrode comprises a negative electrode material layer comprising a negative electrode material layer and a negative electrode interface film formed on the surface of the negative electrode material layer, the specific surface area of the negative electrode material layer is 0.5-5 m 2 / g, the median particle size of the negative electrode material layer is 8-17 μm, the non-aqueous electrolyte comprises a non-aqueous organic solvent, a lithium salt and an additive, the additive comprises a lithium salt type additive and a compound shown in structural formula 1:

[0030] wherein n is 0 or 1, A is selected from C or O, X is selected from R1, R2 are each independently selected from H, R1 and R2 are not simultaneously selected from H, and at least one of X, R1 and R2 contains a sulfur atom;

[0031] The surface of the negative electrode is tested by an X-ray photoelectron spectrometer, and the ratio of the peak area Wa of the inorganic component with a binding energy of 680-685 eV to the peak area Wb of the organic component with a binding energy of 165-175 eV satisfies the condition 0.5≤Wa / Wb≤10.

[0032] The migration rate of lithium ions at the negative electrode interface is a key factor determining the low-temperature impedance, and the migration rate of lithium ions at the negative electrode interface is determined by the negative electrode interface film, and the formation path and composition of the negative electrode interface film are very complex, which are affected by many factors, such as the content of the additive in the electrolyte, the particle size and specific surface area of the negative electrode material layer, the cell preparation process parameters, and the battery formation conditions.

[0033] In the present application, during the battery formation stage, the compound represented by structural formula 1 and the lithium salt type additive will jointly decompose on the surface of the negative electrode material layer to form a negative electrode interface film containing organic and inorganic components mixed with each other, and the inventors have found through a large number of studies that by adjusting the ratio of the compound represented by structural formula 1 and the lithium salt type additive and controlling the specific surface area of the negative electrode material layer to be 0.5-5 m 2 / g, and the median particle size of the negative electrode material layer is 8-17 μm, when the inorganic component Wa of the negative electrode interface film and the organic component Wb of the negative electrode interface film satisfy the condition 0.5≤Wa / Wb≤10, the obtained lithium ion battery can simultaneously have better high-temperature performance and low-temperature performance, and it is speculated that under this condition, a thinner, denser and more stable negative electrode interface film can be formed, and the ratio of the organic component and the inorganic component in the negative electrode interface film is coordinated with each other, which can optimize the lithium ion interface transmission channel, improve the low-temperature performance and the rate performance, and at the same time, the high-temperature storage performance is optimal.

[0034] In some embodiments, the lithium ion battery satisfies the following conditions:

[0035] 0.8≤Wa / Wb≤8.

[0036] When the inorganic component Wa of the negative electrode interface film and the organic component Wb of the negative electrode interface film further satisfy the above conditions, the rate charge-discharge performance, the high-temperature performance and the low-temperature performance of the lithium ion battery can be further improved.

[0037] In some embodiments, the mass percentage content of the compound represented by structural formula 1 is 0.1%-3% based on 100% of the total mass of the non-aqueous electrolyte.

[0038] In preferred embodiments, the mass percentage content of the compound represented by structural formula 1 is 0.1%-2% based on 100% of the total mass of the non-aqueous electrolyte.

[0039] In specific embodiments, the mass percentage content of the compound represented by Structural Formula 1 can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.7%, 0.9%, 1%, 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%, 2.7%, or 3%, based on 100% of the total mass of the non-aqueous electrolyte.

[0040] By adding the compound represented by Structural Formula 1 centered on the S element atom, the compound is superior to general solvents and additives in film formation due to its excellent film formation performance, and can form a stable negative electrode interface film on the negative electrode. It is found through XPS testing that the compound represented by Structural Formula 1 promotes an increase in the content of a sulfur-containing organic matter film component in the composition of the negative electrode interface film. The increase in the organic component in the interface film is conducive to the improvement of electrochemical stability, and in turn is conducive to the inhibition of side reactions between the non-aqueous electrolyte and the negative electrode. In addition, the formed lithium sulfate has an advantage over alkoxy lithium in the transport of lithium ions. If the content of the compound represented by Structural Formula 1 in the non-aqueous electrolyte is too low, the film formation performance of the negative electrode interface film is limited in improvement. If the content of the compound represented by Structural Formula 1 in the non-aqueous electrolyte is too high, the negative electrode interface film will be too thick, the overall degradation resistance will be reduced based on the characteristics of the organic matter film, and the conduction of lithium ions will be adversely affected.

[0041] In some embodiments, the mass percentage content of the lithium salt type additive is 0.01%-2%, based on 100% of the total mass of the non-aqueous electrolyte.

[0042] In preferred embodiments, the mass percentage content of the lithium salt type additive is 0.01%-1%, based on 100% of the total mass of the non-aqueous electrolyte.

[0043] In specific embodiments, the mass percentage content of the lithium salt type additive can be 0.01%, 0.03%, 0.05%, 0.06%, 0.08%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.7%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, or 2.0%, based on 100% of the total mass of the non-aqueous electrolyte.

[0044] The lithium salt type additive has similar kinetics to the compound shown in structural formula 1 after forming a film on the negative electrode, and the lithium salt type additive increases the inorganic component of the negative electrode interfacial film after forming a film on the negative electrode. The increase in the inorganic component significantly improves the thermal stability of the interfacial film and facilitates the conduction of lithium ions. The lithium salt type additive forms a film in an area that overlaps with the compound shown in structural formula 1, which also causes the inorganic and organic components in the negative electrode interfacial film to be stacked in an interleaved manner, without causing the organic and inorganic components to be stacked separately. If the content of the lithium salt type additive in the non-aqueous electrolyte is too low, it is difficult to improve the thermal stability of the negative electrode interfacial film. If the content of the lithium salt type additive in the non-aqueous electrolyte is too high, it is not conducive to the kinetic stability of the interfacial film, and the non-aqueous electrolyte will produce gas and impedance during storage.

[0045] It should be noted that the mass percentage content of the compound shown in structural formula 1 and the mass percentage content of the lithium salt type additive in the non-aqueous electrolyte affect the content of the decomposition products of the compound shown in structural formula 1 and the lithium salt type additive in the negative electrode interfacial film, but are not the only influencing factors. For example, due to the different decomposition potentials of the compound shown in structural formula 1 and the lithium salt type additive, changes in the formation conditions can cause differences in the decomposition of the compound shown in structural formula 1 and the lithium salt type additive, and thus the formation conditions can be used to regulate the ratio of the organic and inorganic components in the negative electrode interfacial film. For another example, the morphology of the negative electrode active material affects the formation of the negative electrode interfacial film. Under different specific surface areas of the negative electrode material layer and particle sizes of the negative electrode material layer, the ratio of the organic and inorganic components in the negative electrode interfacial film obtained is different.

[0046] In some embodiments, the lithium salt type additive includes one or more of LiODFB and LiODFP.

[0047] In some embodiments, the compound shown in structural formula 1 includes one or more of the following compounds:

[0048] In specific embodiments, the specific surface area of the negative electrode material layer can be 0.5 m 2 / g, 0.7 m 2 / g, 0.9 m 2 / g, 1 m 2 / g, 1.1 m 2 / g, 1.2 m 2 / g, 1.3 m 2 / g, 1.4 m 2 / g, 1.5 m 2 / g, 1.8 m 2 / g, 2 m 2 / g, 2.2 m2 / g, 2.5m 2 / g, 2.8m 2 / g, 3m 2 / g, 3.2m 2 / g, 3.5m 2 / g, 3.8m 2 / g, 4m 2 / g, 4.2m 2 / g, 4.5m 2 / g, 4.8m 2 / g or 5m 2 / g.

[0049] In a preferred embodiment, the specific surface area of the negative electrode material layer is 1.0-4m 2 / g.

[0050] The testing method of the specific surface area of the negative electrode material layer is as follows:

[0051] (1) The negative electrode sheet is disassembled from the battery, soaked and cleaned with DMC (dimethyl carbonate), dried in a glove box for 24 hours, and then scraped off from the negative electrode current collector to form a powder. Then the powder is added with a small amount of DMC and dispersed by using an ultrasonic device. After drying, 30-500 mg (different according to the specific surface area of the sample) is loaded into a sample tube.

[0052] (2) The sample tube is loaded into a degassing station, and the sample is heated and vacuum degassed to remove the gas adsorbed on the surface of the material.

[0053] (3) After degassing, the mass of the sample is measured.

[0054] (4) Then the sample is tested for adsorption and desorption by using a BET analyzer (model: JW-BK112, manufacturer: Jingwei Gaobotele).

[0055] (5) The specific surface area is calculated from the adsorption isotherm by computer processing data.

[0056] In a specific embodiment, the median particle size of the negative electrode material layer can be 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm or 17 μm.

[0057] In a preferred embodiment, the median particle size of the negative electrode material layer is 10 μm-15 μm.

[0058] The test method of the median particle size of the negative electrode material layer is as follows: the negative electrode sheet is disassembled from the battery, soaked and cleaned with DMC (dimethyl carbonate), dried in a glove box for 24 h, the negative electrode material layer is scraped off from the negative electrode current collector to form a powder, then the powder is added with a small amount of DMC and dispersed using an ultrasonic device, dried, and then the Dv50 particle size (median particle size) of the negative electrode is tested using a particle size analyzer (model Mastersizer 2000).

[0059] The specific surface area of the negative electrode material layer and the median particle size of the negative electrode material layer both affect the film forming quality of the negative electrode interface film on the surface of the negative electrode material layer and the proportion of organic and inorganic components, specifically, the specific surface area of the negative electrode material layer and the median particle size of the negative electrode material layer affect the contact area between the non-aqueous electrolyte and the negative electrode material layer, under the same formation conditions, affect the consumption rate of the lithium salt type additive and the compound represented by structural formula 1 in the non-aqueous electrolyte, and further control the formation of the negative electrode interface film with different proportions of organic and inorganic components.

[0060] In some embodiments, the negative active material includes at least one of a carbon-based negative electrode, a silicon-based negative electrode, a tin-based negative electrode, and a lithium negative electrode. The carbon-based negative electrode can include graphite, hard carbon, soft carbon, graphene, mesocarbon microbeads, etc.; the silicon-based negative electrode can include silicon material, silicon oxide, silicon-carbon composite material, and silicon alloy material, etc.; the tin-based negative electrode can include tin, tin-carbon, tin-oxygen, tin metal compound; the lithium negative electrode can include metal lithium or lithium alloy. The lithium alloy can be at least one of lithium-silicon alloy, lithium-sodium alloy, lithium-potassium alloy, lithium-aluminum alloy, lithium-tin alloy, and lithium-indium alloy.

[0061] In more preferred embodiments, the negative active material includes at least one of graphite, hard carbon, soft carbon, graphene, and silicon-carbon composite material.

[0062] In some embodiments, the silicon material is one or more of silicon nanoparticles, silicon nanowires, silicon nanotubes, silicon thin films, 3D porous silicon, and hollow porous silicon.

[0063] In some embodiments, the negative electrode further includes a negative electrode current collector, and the negative electrode material layer is covered on the surface of the negative electrode current collector. The negative electrode current collector includes a metal material capable of conducting electrons, preferably, the negative electrode current collector includes at least one of Al, Ni, tin, copper, and stainless steel, and in more preferred embodiments, the negative electrode current collector is selected from copper foil.

[0064] In some embodiments, the negative electrode material layer further includes a negative electrode binder and a negative electrode conductive agent, and the negative active material, the negative electrode binder, and the negative electrode conductive agent are blended to obtain the negative electrode material layer.

[0065] The negative electrode binder includes at least one of polyvinylidene fluoride, a copolymer of vinylidene fluoride, polytetrafluoroethylene, a copolymer of vinylidene fluoride-hexafluoropropylene, a copolymer of tetrafluoroethylene-hexafluoropropylene, a copolymer of tetrafluoroethylene-perfluoroalkyl vinyl ether, a copolymer of ethylene-tetrafluoroethylene, a copolymer of vinylidene fluoride-tetrafluoroethylene, a copolymer of vinylidene fluoride-trifluoroethylene, a copolymer of vinylidene fluoride-trichloroethylene, a copolymer of vinylidene fluoride-fluoroethylene, a copolymer of vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene, a thermoplastic polyimide, a thermoplastic resin such as polyethylene and polypropylene, an acrylic resin, and a styrene butadiene rubber.

[0066] The negative electrode conductive agent includes at least one of conductive carbon black, conductive carbon spheres, conductive graphite, conductive carbon fibers, carbon nanotubes, graphene, or reduced graphene oxide.

[0067] In some embodiments, the formation condition of the lithium ion battery is:

[0068] The formation temperature is 40℃ to 50℃, the formation pressure is 2 to 8 kg / cm 2 , the charging current is 0.05C to 0.12C, and the discharging current is 0.1C to 0.3C.

[0069] In some embodiments, the additive further includes at least one of a cyclic sulfate compound, a sulfonic acid lactone compound, a cyclic carbonate compound, a phosphate compound, a borate compound, and a nitrile compound.

[0070] In some embodiments, the content of the additive is 0.01% to 10% based on 100% of the total mass of the non-aqueous electrolyte solution.

[0071] In some embodiments, the cyclic sulfate compound includes at least one of vinyl ethylene sulfate, 1,3,2-dioxathiane-2,2-dioxide, and methyl vinyl ethylene sulfate.

[0072] In some embodiments, the sulfonic acid lactone compound includes at least one of 1,3-propane sulfonic acid lactone, 1,4-butane sulfonic acid lactone, and 1,3-propylene sulfonic acid lactone.

[0073] In some embodiments, the cyclic carbonate compound includes at least one of vinylene carbonate, vinyl ethylene carbonate, methylene vinyl ethylene carbonate, or a compound represented by Structural Formula 2:

[0074] In the Structural Formula 2, R 21 , R 22 , R 23 , R 24 , R 25 , R26 each independently selected from a hydrogen atom, a halogen atom, and one of C1-C5 groups.

[0075] In some embodiments, the phosphate compound includes at least one of tris(trimethylsilyl) phosphate, tris(triethylsilyl) phosphate, or a compound of structural formula 3:

[0076] In the structural formula 3, R 31 , R 32 , R 33 each independently selected from C1-C5 saturated hydrocarbon groups, C1-C5 unsaturated hydrocarbon groups, C1-C5 halogenated hydrocarbon groups, -Si(C m H 2m+1 )3, m is a natural number of 1-3, and R 31 , R 32 , R 33 at least one of which is an unsaturated hydrocarbon group.

[0077] In preferred embodiments, the phosphate compound of structural formula 3 can be at least one of tripropargyl phosphate, dipropargyl methyl phosphate, dipropargyl ethyl phosphate, dipropargyl propyl phosphate, dipropargyl trifluoromethyl phosphate, dipropargyl-2,2,2-trifluoroethyl phosphate, dipropargyl-3,3,3-trifluoropropyl phosphate, dipropargyl hexafluoroisopropyl phosphate, triallyl phosphate, diallyl methyl phosphate, diallyl ethyl phosphate, diallyl propyl phosphate, diallyl trifluoromethyl phosphate, diallyl-2,2,2-trifluoroethyl phosphate, diallyl-3,3,3-trifluoropropyl phosphate, diallyl hexafluoroisopropyl phosphate.

[0078] In some embodiments, the borate compound includes at least one of tris(trimethylsilyl) borate and tris(triethylsilyl) borate.

[0079] In some embodiments, the nitrile compound includes at least one of butanedinitrile, pentanedinitrile, hexanetristitnitrile, hexanedinitrile, heptanedinitrile, octanedinitrile, nonanedinitrile, decanedinitrile.

[0080] In other embodiments, the additive can further include other additives that can improve the performance of the battery, such as additives that can improve the safety performance of the battery, such as flame-retardant additives such as fluorinated phosphate, cyclic phosphazene, or overcharge-prevention additives such as tert-amylbenzene, tert-butylbenzene, and the like.

[0081] It should be noted that, unless otherwise specified, the content of any one of the optional substances in the nonaqueous electrolyte is less than 10%, preferably, the content is 0.01-5%, more preferably, the content is 0.1%-2%. Specifically, the content of any one of the optional substances in the additive can be 0.01%, 0.05%, 0.08%, 0.1%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 7.8%, 8%, 8.5%, 9%, 9.5%, 10%.

[0082] In some embodiments, the additive comprises fluoroethylene carbonate, and the content of the fluoroethylene carbonate is 0.01%-30% based on the total mass of the nonaqueous electrolyte.

[0083] In some embodiments, the lithium salt comprises at least one of LiPF6, LiBOB, LiPO2F2, LiBF4, LiSbF6, LiAsF6, LiN(SO2F)2, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiC(SO2CF3)3, LiClO4, LiAlCl4, LiCF3SO3, LiSO3F, Li2B 10 Cl 10 , lithium chloroborane, lithium trisoxalate phosphate, lithium lower aliphatic carboxylate having 4 or less carbon atoms, or lithium tetraphenylborate.

[0084] In some embodiments, the concentration of the lithium salt in the nonaqueous electrolyte is 0.1 mol / L-4 mol / L. In preferred embodiments, the concentration of the lithium salt in the nonaqueous electrolyte is 0.5 mol / L-2.5 mol / L. Specifically, the concentration of the lithium salt in the nonaqueous electrolyte can be 0.5 mol / L, 0.55 mol / L, 0.6 mol / L, 0.65 mol / L, 0.7 mol / L, 0.8 mol / L, 0.85 mol / L, 0.9 mol / L, 0.95 mol / L, 1.0 mol / L, 1.1 mol / L, 1.15 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.45 mol / L, 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L, 1.9 mol / L, 2.0 mol / L, 2.1 mol / L, 2.2 mol / L, 2.3 mol / L, 2.4 mol / L, or 2.5 mol / L.

[0085] In some embodiments, the non-aqueous organic solvent has a mass content of 65% to 90% based on 100% of the total mass of the non-aqueous electrolyte.

[0086] Specifically, the non-aqueous organic solvent has a mass content of 65%, 68%, 71%, 74%, 76%, 78%, 79%, 80%, 81.5%, 82%, 84%, 85%, 86%, 87%, 89%, 90% based on 100% of the total mass of the non-aqueous electrolyte.

[0087] In some embodiments, the non-aqueous organic solvent includes at least one of an ether-based solvent, a nitrile-based solvent, a carbonate-based solvent, a carboxylate-based solvent, and a sulfone-based solvent.

[0088] In some embodiments, the ether-based solvent includes a cyclic ether or a chain ether, preferably a chain ether having 3 to 10 carbon atoms and a cyclic ether having 3 to 6 carbon atoms, and the cyclic ether specifically but not exclusively includes at least one of 1,3-dioxolane (DOL), 1,4-dioxane (DX), a crown ether, tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-CH3-THF), and 2-trifluoromethyltetrahydrofuran (2-CF3-THF); and the chain ether specifically but not exclusively includes dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethyleneglycol di-n-propyl ether, ethyleneglycol di-n-butyl ether, and diethylene glycol dimethyl ether. Since the chain ether has high solvating ability for lithium ions and can improve ion dissociation, dimethoxymethane, diethoxymethane, and ethoxymethoxymethane, which have low viscosity and can impart high ionic conductivity, are particularly preferred. The ether-based compound can be used alone or in combination of two or more in any combination and ratio. The amount of the ether-based compound added is not particularly limited and is arbitrary within a range that does not significantly impair the effects of the high-density lithium ion battery according to the present application, and is typically 1% or more by volume, preferably 2% or more by volume, and more preferably 3% or more by volume, in 100% of the non-aqueous solvent, and is typically 30% or less by volume, preferably 25% or less by volume, and more preferably 20% or less by volume.

[0089] In some embodiments, the nitrile-based solvent specifically but not exclusively includes at least one of acetonitrile, glutaronitrile, and malononitrile.

[0090] In some embodiments, the carbonate-based solvent includes a cyclic carbonate or a chain carbonate, and the cyclic carbonate can specifically but not exclusively be at least one of ethylene carbonate (EC), propylene carbonate (PC), γ-butyrolactone (GBL), or butylene carbonate (BC), and the chain carbonate can specifically but not exclusively be at least one of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), or dipropyl carbonate (DPC). The content of the cyclic carbonate is not particularly limited and is arbitrary within a range that does not significantly impair the effects of the lithium ion battery of the present application, but in the case of using one alone, the lower limit of the content is generally 3% by volume or more, and preferably 5% by volume or more, relative to the total amount of the solvent of the nonaqueous electrolyte. By setting this range, it is possible to avoid a decrease in the electric conductivity due to a decrease in the dielectric constant of the nonaqueous electrolyte, and to easily bring the large-current discharge characteristics, the stability with respect to the negative electrode, and the cycle characteristics of the nonaqueous electrolyte battery to a good range. In addition, the upper limit is generally 90% by volume or less, preferably 85% by volume or less, and more preferably 80% by volume or less. By setting this range, it is possible to improve the oxidation / reduction resistance of the nonaqueous electrolyte, thereby contributing to an improvement in the stability during high-temperature storage. The content of the chain carbonate is not particularly limited and is generally 15% by volume or more, preferably 20% by volume or more, and more preferably 25% by volume or more, relative to the total amount of the solvent of the nonaqueous electrolyte. In addition, it is generally 90% by volume or less, preferably 85% by volume or less, and more preferably 80% by volume or less. By bringing the content of the chain carbonate within the above range, it is possible to easily bring the viscosity of the nonaqueous electrolyte to an appropriate range, to suppress a decrease in the ionic conductivity, and to further contribute to bringing the output characteristics of the nonaqueous electrolyte battery to a good range. In the case of using two or more chain carbonates in combination, it is sufficient to bring the total amount of the chain carbonates to the above range.

[0091] In some embodiments, it can also be preferable to use a chain carbonate having a fluorine atom (hereinafter referred to simply as "fluorinated chain carbonate"). The number of fluorine atoms possessed by the fluorinated chain carbonate is not particularly limited as long as it is one or more, but is generally six or less, and preferably four or less. In the case where the fluorinated chain carbonate has a plurality of fluorine atoms, these fluorine atoms can be bonded to the same carbon or to different carbons. As the fluorinated chain carbonate, there can be mentioned, for example, a fluorinated dimethyl carbonate derivative, a fluorinated ethyl methyl carbonate derivative, a fluorinated diethyl carbonate derivative, and the like.

[0092] The carboxylic acid ester-based solvent includes a cyclic carboxylic acid ester and / or a chain carbonate. As examples of the cyclic carboxylic acid ester, there can be mentioned, for example, at least one of γ-butyrolactone, γ-valerolactone, δ-valerolactone, and the like. As examples of the chain carbonate, there can be mentioned, for example, at least one of methyl acetate (MA), ethyl acetate (EA), propyl acetate (EP), butyl acetate, propyl propionate (PP), butyl propionate, and the like.

[0093] In some embodiments, the sulfone-based solvent includes cyclic sulfones and chain sulfones, preferably, in the case of cyclic sulfones, compounds having generally 3 to 6 carbon atoms, preferably 3 to 5 carbon atoms, and in the case of chain sulfones, compounds having generally 2 to 6 carbon atoms, preferably 2 to 5 carbon atoms. The amount of the sulfone-based solvent added is not particularly limited and is arbitrary within a range that does not significantly impair the effects of the lithium ion battery of the present application, and is generally 0.3% by volume or more, preferably 0.5% by volume or more, more preferably 1% by volume or more, and, in addition, is generally 40% by volume or less, preferably 35% by volume or less, more preferably 30% by volume or less, with respect to the total amount of the solvent of the nonaqueous electrolyte. In the case where two or more kinds of sulfone-based solvents are used in combination, the total amount of the sulfone-based solvents is made to satisfy the above range. When the amount of the sulfone-based solvent added is within the above range, a nonaqueous electrolyte excellent in high-temperature storage stability tends to be obtained.

[0094] In preferred embodiments, the nonaqueous organic solvent includes a mixture of cyclic carbonates and chain carbonates.

[0095] In some embodiments, the positive electrode material layer includes a positive electrode active material, the positive electrode material layer includes a positive electrode active material, the positive electrode active material is selected from at least one of LiFe 1-x’ M’ x’ PO4, LiMn 2-y’ M y’ O4, and LiNi x Co y Mn z M 1-x-y-z O2, wherein M’ is selected from at least one of Mn, Mg, Co, Ni, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, Zr, W, V, or Ti, M is selected from at least one of Fe, Co, Ni, Mn, Mg, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, Zr, W, V, or Ti, and 0≤x’<1, 0≤y’≤1, 0≤y≤1, 0≤x≤1, 0≤z≤1, x+y+z≤1.

[0096] In some embodiments, the molar ratio of Ni element in the positive electrode active material is ≥0.3.

[0097] In preferred embodiments, the molar ratio of Ni element in the positive electrode active material is 0.3 to 0.7.

[0098] In some embodiments, the positive electrode material layer further includes a positive electrode binder and a positive electrode conductive agent, and the positive electrode active material, the positive electrode binder, and the positive electrode conductive agent are blended to obtain the positive electrode material layer.

[0099] The positive electrode binder includes at least one of polyvinylidene fluoride, a copolymer of vinylidene fluoride, polytetrafluoroethylene, a copolymer of vinylidene fluoride-hexafluoropropylene, a copolymer of tetrafluoroethylene-hexafluoropropylene, a copolymer of tetrafluoroethylene-perfluoroalkyl vinyl ether, a copolymer of ethylene-tetrafluoroethylene, a copolymer of vinylidene fluoride-tetrafluoroethylene, a copolymer of vinylidene fluoride-trifluoroethylene, a copolymer of vinylidene fluoride-trichloroethylene, a copolymer of vinylidene fluoride-vinylidene fluoride, a copolymer of vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene, a thermoplastic polyimide, a thermoplastic resin such as polyethylene and polypropylene, an acrylic resin, and a styrene butadiene rubber.

[0100] The positive electrode conductive agent includes at least one of conductive carbon black, conductive carbon spheres, conductive graphite, conductive carbon fibers, carbon nanotubes, graphene, or reduced graphene oxide.

[0101] In some embodiments, the positive electrode current collector includes an electron-conducting metal material, preferably, the positive electrode current collector includes at least one of Al, Ni, tin, copper, and stainless steel, and in more preferred embodiments, the positive electrode current collector is selected from an aluminum foil.

[0102] In some embodiments, the lithium ion battery further includes a separator between the positive electrode and the negative electrode.

[0103] The separator can be a conventional separator, and can be a ceramic separator, a polymer separator, a non-woven fabric, an inorganic-organic composite separator, etc., including but not limited to a single-layer PP (polypropylene) separator, a single-layer PE (polyethylene) separator, a double-layer PP / PE separator, a double-layer PP / PP separator, and a three-layer PP / PE / PP separator.

[0104] In some embodiments, the lithium ion battery has a charge cut-off voltage of ≥4.35 V.

[0105] In preferred embodiments, the lithium ion battery has a charge cut-off voltage of 4.35 V to 4.5 V.

[0106] The application is further described below by way of examples.

[0107] Table 1

[0108] Example 1

[0109] This example is used to illustrate the preparation method of the lithium ion battery disclosed in the application, which includes the following operation steps:

[0110] 1) Preparation of electrolyte

[0111] Ethylene carbonate (EC), diethyl carbonate (DEC) and ethylmethyl carbonate (EMC) were mixed in a mass ratio of EC:DEC:EMC = 1:1:1, then lithium hexafluorophosphate (LiPF6) was added to a molar concentration of 1 mol / L, and the additives shown in Table 1 were added in an amount of 5% by mass based on the total mass of the electrolyte.

[0112] 2) Preparation of positive electrode sheet

[0113] A positive electrode active material LiNi 0.6 Co 0.2 Mn 0.2 O2, conductive carbon black (Super-P) and a binder polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 93:4:3, and then dispersed in N-methyl-2-pyrrolidone (NMP) to obtain a positive electrode slurry. The slurry was uniformly coated on both sides of an aluminum foil, dried, calendered and vacuum-dried, and then an aluminum lead wire was welded thereto using an ultrasonic welder to obtain a positive electrode sheet having a thickness of 120-150 μm.

[0114] 3) Preparation of negative electrode sheet

[0115] A negative electrode active material artificial graphite, conductive carbon black Super-P, a binder styrene-butadiene rubber (SBR) and carboxymethyl cellulose (CMC) were mixed in a mass ratio of 94:1:2.5:2.5, and then dispersed in deionized water to obtain a negative electrode slurry. The slurry was coated on both sides of a copper foil, dried, calendered and vacuum-dried, and then a nickel lead wire was welded thereto using an ultrasonic welder to obtain a negative electrode sheet having a thickness of 120-150 μm, and the median particle diameter and specific surface area of the negative electrode material layer were as shown in Table 1.

[0116] 4) Preparation of battery cell

[0117] A three-layer separator having a thickness of 20 μm was placed between the positive electrode sheet and the negative electrode sheet, and then the sandwich structure of the positive electrode sheet, the negative electrode sheet and the separator was wound, and the wound body was flattened and placed in an aluminum foil packaging bag, and vacuum baked at 75°C for 48 h to obtain a battery cell to be impregnated with electrolyte.

[0118] 5) Impregnation of battery cell with electrolyte and formation

[0119] The electrolyte prepared as described above was impregnated into the battery cell in a glove box in which the dew point was controlled to be below -40°C, and vacuum packaged, and then allowed to stand for 24 h. Then, first charge formation was performed under the following conditions: formation temperature of 45°C, formation pressure of 4 kg / cm 2 , charge current of 0.1C and discharge current of 0.2C.

[0120] Examples 2 to 45

[0121] Examples 2 to 45 are used to illustrate the preparation method of the lithium ion battery disclosed in the present application, including most of the operation steps in Example 1, the difference is that:

[0122] The positive active material type, the additive and its additive amount in the non-aqueous electrolyte, the median particle size of the negative electrode material layer, and the specific surface area of the negative electrode material layer are shown in Table 1.

[0123] The positive active material in Example 39 is LiNi 0.5 Co 0.25 Mn 0.3 O2, the positive active material in Example 40 is LiNi 0.7 Co 0.1 Mn 0.2 O2, the positive active material in Example 41 is LiNi 0.6 Co 0.2 Al 0.2 O2, the positive active material in Example 42 is LiNi 0.6 Co 0.2 Mn 0.05 Al 0.05 O2.

[0124] Comparative Examples 1 to 12

[0125] Comparative Examples 1 to 12 are used to compare the preparation method of the lithium ion battery disclosed in the present application, including most of the operation steps in Example 1, the difference is that:

[0126] The additive and its additive amount in the non-aqueous electrolyte, the median particle size of the negative electrode material layer, and the specific surface area of the negative electrode material layer are shown in Table 1.

[0127] Performance test

[0128] The lithium ion battery prepared above is subjected to the following performance test:

[0129] I. Test by X-ray photoelectron spectrometer (XPS)

[0130] The lithium ion battery was discharged to 2.5V at a current of 0.1C, and the negative electrode sheet was obtained by disassembling the lithium ion battery in an argon-filled glove box. The obtained negative electrode sheet was cut into a test sample with a size of 5mm x 5mm, and was soaked and cleaned with a low-boiling-point dimethyl carbonate (DMC) solvent for 30 seconds. After drying completely, the negative electrode material layer was pasted on the sample table of the XPS with the surface away from the current collector facing upward, and the measurement was carried out without exposure to the atmosphere. The specific test conditions and steps are as follows: etching was carried out using an Ar ion gun at a speed of 10nm / min, the etching power was 1kV, the data at an etching time of 0s were selected for data processing, the peak area of the inorganic component at a binding energy of 680-685eV was taken, and the peak area of the organic component at a binding energy of 165-175eV was taken. The background was deducted and the peaks were synthesized to calculate the ratio of the peak area Wa of the inorganic component to the peak area Wb of the organic component in the negative electrode interfacial film. The test results were filled in Table 1.

[0131] II. High-temperature cycle performance test

[0132] The lithium ion battery after formation was placed in an oven at a constant temperature of 45℃, and was charged to the cut-off voltage at a current of 1C, and then was charged at a constant voltage until the current decreased to 0.02C, and then was discharged to 3.0V at a current of 1C. The discharge capacity of the first cycle and the discharge capacity of the last cycle were recorded.

[0133] The capacity retention rate of high-temperature cycle was calculated according to the following formula:

[0134] The capacity retention rate (%) = the discharge capacity of the last cycle / the discharge capacity of the first cycle x 100%.

[0135] III. Rate cycle performance test

[0136] The lithium ion battery after formation was placed in an oven at a constant temperature of 25℃, and was charged to 80% SOC at a current of 4C, and then was charged at a constant current and constant voltage to the cut-off voltage at a current of 1C, and then was discharged to 3.0V at a current of 1C. The discharge capacity of the first cycle and the discharge capacity of the last cycle were recorded.

[0137] The capacity retention rate of rate cycle was calculated according to the following formula:

[0138] The capacity retention rate (%) = the discharge capacity of the last cycle / the discharge capacity of the first cycle x 100%.

[0139] IV. High-temperature storage performance test

[0140] The lithium ion battery after formation is charged at room temperature with 0.5C constant current and constant voltage to the cut-off voltage, the initial discharge capacity and initial battery thickness of the battery are measured, then after 30 days of storage in 60°C environment, the battery is discharged at 1C to 3V, the retention capacity and recovery capacity of the battery and the battery thickness after storage are measured. The calculation formula is as follows:

[0141] Battery capacity retention rate (%) = retention capacity / initial capacity x 100%;

[0142] Battery capacity recovery rate (%) = recovery capacity / initial capacity x 100%;

[0143] Thickness expansion rate (%) = (battery thickness after storage-initial battery thickness) / initial battery thickness x 100%.

[0144] V. Low temperature performance test

[0145] At 25°C, the battery after formation is charged with 1C constant current and constant voltage to the cut-off voltage, then discharged with 1C constant current to 3.0V, and the discharge capacity is recorded. Then charged with 1C constant current and constant voltage to the cut-off voltage, placed in an environment of-20°C for 12h, and discharged with 0.5C constant current to 3.0V, and the discharge capacity is recorded.

[0146] Low temperature discharge efficiency value at-20°C (%) = 0.5C discharge capacity(-20°C) / 1C discharge capacity(25°C) x 100%.

[0147] (1) The test results of examples 1-30 and comparative examples 1-12 are filled in table 2.

[0148] Table 2

[0149] From the test results of examples 1-30 and comparative examples 1-12, in the battery system added with the compound shown in structural formula 1 and the lithium salt type additive, by controlling the ratio of the compound shown in structural formula 1 and the lithium salt type additive and the specific surface area of the negative electrode material layer to be 0.5-5m 2 / g, the median particle size of the negative electrode material layer to be 8μm-17μm, and the inorganic component Wa of the negative electrode interface film and the organic component Wb of the negative electrode interface film satisfy the condition 0.5≤Wa / Wb≤10, the obtained lithium ion battery simultaneously has better high temperature performance, low temperature performance and high rate charge-discharge performance, it is speculated that under this condition, a thinner, denser and more stable negative electrode interface film can be formed, and the ratio of the organic component and the inorganic component in the negative electrode interface film is coordinated with each other, which can optimize the lithium ion interface transmission channel, improve the low temperature performance and the rate performance, and the high temperature storage performance reaches the optimum.

[0150] From the test results of Examples 1-30, when the inorganic component Wa of the negative electrode interface film and the organic component Wb of the negative electrode interface film further satisfy the condition 0.8≤Wa / Wb≤8, the high-temperature stability and ion conductivity of the solid electrolyte film on the surface of the negative electrode material layer are further improved, and the high-temperature performance, low-temperature performance, and rate performance of the battery all reach a high level.

[0151] From the test results of Comparative Examples 5-12, when the value of Wa / Wb does not satisfy the limitation 0.5≤Wa / Wb≤10, even if the compound of structural formula 1 and the lithium salt type additive are added and the addition amount of the compound of structural formula 1 and the lithium salt type additive satisfies the range limitation, the obtained lithium ion battery still cannot balance the high and low temperature performance, which shows that through the adjustment of the specific surface area of the negative electrode material layer and the median particle size of the negative electrode material layer, the ratio of the organic component and the inorganic component in the negative electrode interface film will also be affected, and only when the multiple influencing factors reach a better balance state, the high-temperature stability and ion conductivity of the negative electrode interface film of the negative electrode material layer interface can be improved.

[0152] From the test results of Comparative Examples 1-4, when the compound of structural formula 1 and the lithium salt type additive are not used as electrolyte additives at the same time, even if the value of Wa / Wb is adjusted to satisfy the limitation 0.5≤Wa / Wb≤10, it will lead to the deterioration of the high-temperature performance, low-temperature performance, and rate performance of the lithium ion battery, which shows that the condition limitation of the battery system is only applicable to the electrolyte system with the compound of structural formula 1 and the lithium salt type additive, and the performance improvement is directly related to the compound of structural formula 1 and the lithium salt type additive.

[0153] (2) The test results of Examples 1, 31-38 are filled in Table 3.

[0154] Table 3

[0155] From the test results of Examples 1, 31-38, when different compounds of structural formula 1 and lithium salt type additives are used, under the condition of satisfying 0.5≤Wa / Wb≤10, lithium ion batteries with excellent high-temperature storage performance, large-rate charge and discharge performance, and low-temperature discharge capacity retention rate can be obtained, which shows that the battery system provided by the application is suitable for different compounds of structural formula 1 and lithium salt type additives.

[0156] (3) The test results of Examples 1, 39-42 are filled in Table 4.

[0157] Table 4

[0158] From the test results of Examples 1, 39-42, it can be seen that in the battery system provided by the present application, when different positive active materials are used, the performances of the lithium ion battery will be affected to some extent, but generally, the lithium ion battery satisfying the condition 0.5≤Wa / Wb≤10 maintains a relatively optimal level in high-temperature performance, low-temperature performance and rate performance.

[0159] (4) The test results obtained from Examples 1, 43-45 are filled in Table 5.

[0160] Table 5

[0161] From the test results of Examples 1, 43-45, it can be seen that when DTD (vinyl sulfate), PS (1, 3-propane sulfone lactone) or FEC (fluorinated ethylene carbonate) is used in combination with the compound shown in structural formula 1 and the lithium salt type additive, the high and low temperature performances of the lithium ion battery are improved to some extent, which is presumably due to the fact that the improvement mechanisms of the other additives on the battery performance are different from those of the compound shown in structural formula 1 and the lithium salt type additive, and the three additives have a complementary effect on film formation, thereby improving the stability of the interface film on the surface of the negative electrode material layer and further improving the cycle stability and high and low temperature performances of the battery.

[0162] The above only describes the preferred embodiments of the present application and should not be used to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A lithium-ion battery, characterized by, A non-aqueous electrolyte secondary battery includes a positive electrode, a negative electrode, and a non-aqueous electrolyte. The negative electrode includes a negative electrode material layer including a negative electrode active material and a negative electrode interface film formed on a surface of the negative electrode material layer. The specific surface area of the negative electrode material layer is 0.5 to 5 m 2 / g. The median particle diameter of the negative electrode material layer is 8 μm to 17 μm. The non-aqueous electrolyte includes a non-aqueous organic solvent, a lithium salt, and an additive. The additive includes a lithium salt type additive and a compound represented by Structural Formula 1: wherein n is 0 or 1, A is selected from C or O, and X is selected from R1, R2are each independently selected from H, R1 and R2 are not simultaneously selected from H, and X, R1 and R2 contain at least one sulfur atom; The ratio of the peak area Wa of the inorganic component with a binding energy of 680-685 eV to the peak area Wb of the organic component with a binding energy of 165-175 eV meets the condition: 0.5≤Wa / Wb≤10.

2. The lithium-ion battery of claim 1, wherein, The lithium ion battery meets the following conditions: 0.8≤Wa / Wb≤8.

3. The lithium-ion battery of claim 1, wherein, The mass percentage content of the compound represented by the structural formula 1 is 0.1%-3% based on the total mass of the non-aqueous electrolyte being 100%.

4. The lithium-ion battery of claim 1, wherein, The mass percentage content of the lithium salt type additive is 0.01%-2% based on the total mass of the non-aqueous electrolyte being 100%.

5. The lithium-ion battery of claim 1 or 4, wherein, The lithium salt type additive comprises one or more of LiODFB and LiODFP.

6. The lithium-ion battery of claim 1, wherein, The compound of Structural Formula 1 includes one or more of the following compounds:

7. The lithium-ion battery of claim 1, wherein, The specific surface area of the negative electrode material layer is 1.0-4 m 2 / g.

8. The lithium-ion battery of claim 1, wherein, The median particle size of the negative electrode material layer is 10-15 μm.

9. The lithium-ion battery of claim 1, wherein, The formation conditions of the lithium ion battery are: The formation temperature is 40-50°C, the formation pressure is 2-8 kg / cm 2 , the charging current is 0.05-0.12 C, and the discharging current is 0.1-0.3 C.

10. The lithium-ion battery of claim 1, wherein, The additive further comprises at least one of a cyclic sulfate compound, a sulfonic acid lactone compound, a cyclic carbonate compound, a phosphate compound, a borate compound and a nitrile compound.

11. The lithium-ion battery of claim 10, wherein, The cyclic sulfate compound comprises at least one of vinyl sulfate, 1,3,2-dioxathiane-2,2-dioxide and methyl vinyl sulfate.

12. The lithium-ion battery of claim 10, wherein, The sulfonic acid lactone compound comprises at least one of 1,3-propane sulfonic acid lactone, 1,4-butane sulfonic acid lactone and 1,3-propylene sulfonic acid lactone.

13. The lithium-ion battery of claim 10, wherein, The cyclic carbonate compound includes at least one of vinylene carbonate, vinyl ethylene carbonate, methylene vinyl carbonate, or a compound represented by Structural Formula 2: In the structural formula 2, R 21 , R 22 , R 23 , R 24 , R 25 , R 26 is independently selected from a hydrogen atom, a halogen atom, one of C1-C5 groups.

14. The lithium-ion battery of claim 10, wherein, The phosphate compound includes at least one of tris(trimethylsilyl)phosphate, tris(triethylsilyl)phosphate, or a compound of Formula 3: In the structural formula 3, R 31 , R 32 , R 33 are each independently selected from a C1-C5 saturated hydrocarbon group, a C1-C5 unsaturated hydrocarbon group, a C1-C5 halogenated hydrocarbon group, -Si(C m H 2m+1 )3, m is a natural number of 1 to 3, and R 31 , R 32 , R 33 at least one of which is an unsaturated hydrocarbon group.

15. The lithium-ion battery of claim 10, wherein, The borate compound comprises at least one of tris(trimethylsilyl) borate and tris(triethylsilyl) borate.

16. The lithium-ion battery of claim 10, wherein, The nitrile compound comprises at least one of butanedinitrile, pentanedinitrile, hexanetristitnitrile, hexanedinitrile, heptanedinitrile, octanedinitrile, nonanedinitrile and decanedinitrile.

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