Application of unsaturated silane compound in lithium ion battery, lithium ion battery and electric device

Abstract

The invention belongs to the field of battery materials, and particularly relates to application of an unsaturated silane compound in a lithium ion battery, the lithium ion battery and an electric device. The lithium ion battery comprises an electrolyte, and the electrolyte comprises a lithium salt, a solvent and an unsaturated silane compound. According to the invention, the unsaturated silane compound is added into the electrolyte, so that gas production of a lithium supplement system cell can be inhibited.

Description

Technical Field

[0001] The invention belongs to the field of battery materials, and in particular relates to the application of unsaturated silane compounds in lithium ion batteries, lithium ion batteries and electrical devices. Background Art

[0002] During the first charge and discharge process of lithium-ion batteries, some lithium ions will be irreversibly lost due to changes in the structure of the positive electrode material and the formation of a solid electrolyte interface (SEI) film on the electrode surface. Adding a lithium supplement can release additional lithium ions when the battery is first charged to compensate for this loss, thereby improving the battery's initial charge and discharge efficiency and increasing the battery's actual available capacity. By supplementing the lithium source, the positive electrode material can store and release more lithium ions in subsequent charge and discharge cycles, which helps to improve the overall energy density of the battery, allowing the battery to store more electrical energy at the same volume or weight, extending the battery's service life and range.

[0003] Li 5 FeO 4 It is an orthorhombic Pbca crystal type lithium-rich cathode material. Theoretically, each mole of Li 5 FeO 4 Can provide 5 Li + , the specific capacity can be as high as 867mAh / g, and the irreversible capacity is about 693mAh / g. By mixing a certain amount of Li 5 FeO 4 As a lithium supplement, it can significantly improve the initial efficiency and energy density of lithium-ion batteries.

[0004] Li 5 FeO 4 The following reactions mainly occur during the charging process of lithium-ion batteries: A two-phase reaction occurs at the first charging platform (3.5-4.0 V), and the antifluorite structure transforms into a pseudocubic structure: Li 5 FeO 4 → Li 3 FeO 3.5 + 0.25O 2 ↑ + 2Li + +2e - ; A single-phase reaction occurs at the second charging platform (4.0 V), and the pseudocubic structure transforms into another pseudocubic structure: Li 3 FeO 3.5 → LiFeO 2 + 0.75O 2 ↑ + 2Li + +2e - .

[0005] Therefore, Li 5 FeO 4 When lithium ions are decomposed and released, oxygen free radicals are generated to generate oxygen, which in turn oxidizes the electrolyte to generate CO. 2 , CO and H 2 O; Li 5 FeO 4 After decomposition, the structure is unstable, and side reactions with the electrolyte will occur during volume separation, high-temperature storage and circulation, leading to gas production.

[0006] Targeting Li 5 FeO 4 Regarding the existing gas production problem, CN116706285A proposes to use a small current formation in the charging voltage platform area to fully activate LFO to release oxygen, thereby reducing the battery storage gas production and improving the battery cycle performance. However, this method produces a large amount of gas in the formation stage, which is very likely to cause bubbles on the formation interface and prolong the formation time, which is not conducive to improving production efficiency. CN117393932A proposes to set a breathable member on the cover assembly of the battery cell so that the gas released by the lithium supplement during the sustained release process can be discharged from the battery cell, which to a certain extent improves the problem of excessive gas production during the sustained release of the lithium supplement causing the battery cell to open the valve in advance. However, this method does not fundamentally solve the oxygen released by the lithium supplement LFO, and the interface problem caused by the gas and the impact on the performance of the battery cell cannot be eliminated.

[0007] In summary, this field urgently needs to solve the gas production problem of LFO lithium supplement during high-temperature storage and cycling, improve the cycling performance and high-temperature storage performance of battery cells, and improve the dark lines on the negative electrode interface. Summary of the invention

[0008] In view of the above problems existing in the prior art, the present invention proposes the application of unsaturated silane compounds in lithium ion batteries, lithium ion batteries and electrical devices. The present invention adds unsaturated silane compounds to the electrolyte to suppress gas generation in lithium supplement system batteries.

[0009] Specifically, one aspect of the present invention provides an unsaturated silane compound in a Li-containing 5 FeO 4 Application in the electrolyte of lithium-ion batteries, or in electrolytes containing Li 5 FeO 4 Application in lithium-ion batteries, or in improving the 5 FeO 4 Application in gas production, cycle performance, storage performance and / or dark lines on negative electrode interface of lithium-ion batteries.

[0010] In one or more embodiments, the unsaturated silane compound is a compound of formula I: ; In Formula I, R 1 , R 2 , R 3 , R 4 are each independently selected from C1-C4 alkyl, C2-C4 alkenyl and C2-C4 alkynyl, and R 1 , R 2 , R 3 , R 4 They are not C1-C4 alkyl at the same time.

[0011] In one or more embodiments, R 1 , R 2 , R 3 , R 4 Each is independently selected from C1-C4 alkyl and C2-C4 alkenyl.

[0012] In one or more embodiments, R 1 , R 2 , R 3 , R 4 Each is independently selected from C1-C3 alkyl and C2-C3 alkenyl.

[0013] In one or more embodiments, R 1 , R 2 , R 3 , R 4 Each is independently selected from methyl, ethyl, vinyl and allyl.

[0014] In one or more embodiments, the unsaturated silane compound is selected from tetravinylsilane, vinyltrimethylsilane, divinyldimethylsilane, trivinylmethylsilane, allyltriethylsilane, diallyldiethylsilane, triallylethylsilane, and tetraallylsilane.

[0015] In one or more embodiments, the mass fraction of the unsaturated silane compound in the electrolyte is 0.001wt%-2wt%, preferably 0.01wt%-2wt%, more preferably 0.05wt%-2wt%, more preferably 0.1wt%-2wt%, for example 0.5wt%-1.5wt%, 0.8wt%-1wt%.

[0016] In one or more embodiments, the lithium-ion battery includes a positive electrode sheet, the positive electrode sheet includes a positive electrode material layer, the positive electrode material layer includes a positive electrode active material and Li 5 FeO 4 , Li 5 FeO 4 The quality and Li 5 FeO 4The ratio of the total mass of the positive electrode active material is 0.1wt%-5wt%, preferably 0.5wt%-4wt%, more preferably 1wt%-3.5wt%, for example 1.5wt%-2.5wt%.

[0017] In one or more embodiments, Li 5 FeO 4 The particle size D50 is 5-10μm.

[0018] In one or more embodiments, Li 5 FeO 4 The specific surface area is 0.3-5m 2 / g.

[0019] In one or more embodiments, the positive electrode material layer is disposed on one surface or both surfaces of the positive electrode current collector.

[0020] In one or more embodiments, the lithium-ion battery comprises a positive electrode sheet and an electrolyte, wherein the positive electrode sheet comprises a positive electrode material layer, wherein the positive electrode material layer comprises a positive electrode active material and Li 5 FeO 4 The electrolyte includes the unsaturated silane compound, Li 5 FeO 4 The quality and Li 5 FeO 4 The ratio of the total mass of the positive electrode active material is P, the mass fraction of the unsaturated silane compound in the electrolyte is Q, P / Q≤30; preferably, P / Q≤25; more preferably, P / Q≤10; more preferably, P / Q≤5; more preferably, P / Q≤2.5.

[0021] In one or more embodiments, the lithium-ion battery includes a positive electrode sheet, the positive electrode sheet includes a positive electrode material layer, the positive electrode material layer includes a positive electrode active material and Li 5 FeO 4 The positive electrode active material is selected from one or more of lithium iron phosphate, lithium manganese iron phosphate, lithium manganate, nickel-cobalt-manganese ternary positive electrode material, nickel-cobalt-aluminum ternary positive electrode material and nickel-cobalt-manganese-aluminum quaternary positive electrode material.

[0022] In one or more embodiments, the electrolyte does not contain cyclic lithium borate compounds, including lithium difluorooxalatoborate, lithium difluoromalonateborate, lithium bisoxalatoborate, and lithium difluorooxalatoborate.

[0023] Another aspect of the present invention provides a method for containing Li 5 FeO 4An electrolyte for a lithium-ion battery, the electrolyte comprising a lithium salt, a solvent and an unsaturated silane compound.

[0024] In one or more embodiments, the electrolyte comprises a lithium salt, a solvent, and an unsaturated silane compound, and the electrolyte does not comprise a cyclic lithium borate compound.

[0025] In one or more embodiments, the cyclic lithium borate compounds include lithium difluorooxalatoborate, lithium difluoromalonateborate, lithium bisoxalatoborate, and lithium difluorooxalatoborate.

[0026] In one or more embodiments, the unsaturated silane compound in the electrolyte is the unsaturated silane compound described in any embodiment herein.

[0027] In one or more embodiments, the lithium salt is selected from LiFSI, LiPF 6 , LiTFSI and LiBF 4 One or more of .

[0028] In one or more embodiments, the mass fraction of the lithium salt in the electrolyte is 6 wt %-20 wt %, preferably 8 wt %-15 wt %.

[0029] In one or more embodiments, the solvent is selected from one or more of ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, propylene carbonate, diethyl carbonate, ethyl acetate, and ethyl propionate.

[0030] In one or more embodiments, the mass fraction of the unsaturated silane compound in the electrolyte is 0.001wt%-2wt%, preferably 0.01wt%-2wt%, more preferably 0.05wt%-2wt%, more preferably 0.1wt%-2wt%, for example 0.5wt%-1.5wt%, 0.8wt%-1wt%.

[0031] In one or more embodiments, the electrolyte further comprises an additive, wherein the additive comprises one or more of an alkane film-forming additive, a silicon-based phosphate film-forming additive, a silicon-based phosphite film-forming additive, a silicon-based borate film-forming additive, a sulfur-based additive, and a lithium salt additive, wherein the alkane film-forming additive is preferably selected from one or more of vinylene carbonate, fluoroethylene carbonate, and vinyl ethylene carbonate, wherein the silicon-based phosphate additive is preferably selected from one or more of tris(trimethylsilane) phosphate, tris(vinyldimethylsilane) phosphate, and diethyltrimethylsilyl phosphate, wherein the silicon-based phosphite additive is selected from one or more of tris(trimethylsilane) phosphate, tris(vinyldimethylsilane) phosphate, and diethyltrimethylsilyl phosphate. The agent is preferably selected from one or more of tris(trimethylsilane)phosphite, tris(vinyldimethylsilane)phosphite and diethyltrimethylsilylphosphite, the silicon-based borate film-forming additive is preferably selected from one or more of tris(trimethylsilane)borate, tris(vinyldimethylsilane)borate and diethyltrimethylsilylborate, the sulfur-based additive is preferably selected from one or more of vinyl sulfate, vinyl sulfite, propenyl-1,3-sultone, methylene disulfonate, 1,3-propanesultone and 1,3-butanesultone, the lithium salt additive is preferably selected from lithium difluorophosphate (LiPO 2 F 2 ), one or more of lithium difluorooxalatoborate (LiODFB), lithium difluorooxalatophosphate (LiODFP) and lithium tetrafluorooxalatophosphate (LiOTFP), more preferably selected from LiPO 2 F 2 , LiODFP and LiOTFP, and the mass fraction of the additive in the electrolyte is preferably 0.1wt%-5wt%.

[0032] Another aspect of the present invention provides a secondary battery, the secondary battery comprising a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator, the positive electrode sheet comprising a positive electrode current collector and a positive electrode material layer, the positive electrode material layer comprising a positive electrode active material and a lithium supplement, the lithium supplement comprising Li 5 FeO 4 , the electrolyte comprises a lithium salt, a solvent and an unsaturated silane compound.

[0033] In one or more embodiments, the secondary battery is a lithium ion battery.

[0034] In one or more embodiments, the unsaturated silane compound is as described in any embodiment herein.

[0035] In one or more embodiments, the electrolyte is as described in any of the embodiments herein.

[0036] In one or more embodiments, the positive electrode active material is selected from one or more of lithium iron phosphate, lithium iron manganese phosphate, lithium manganate, nickel cobalt manganese ternary positive electrode material, nickel cobalt aluminum ternary positive electrode material and nickel cobalt manganese aluminum quaternary positive electrode material.

[0037] In one or more embodiments, the positive electrode material layer is disposed on one surface or both surfaces of the positive electrode current collector.

[0038] In one or more embodiments, the negative electrode sheet includes a negative electrode current collector and a negative electrode material layer, the negative electrode material layer includes a negative electrode active material, and the negative electrode active material is selected from one or more of graphite and silicon-carbon composite materials.

[0039] In one or more embodiments, the negative electrode material layer is disposed on one surface or both surfaces of the negative electrode collector.

[0040] In one or more embodiments, Li 5 FeO 4 The particle size D50 is 5-10μm.

[0041] In one or more embodiments, Li 5 FeO 4 The specific surface area is 0.3-5m 2 / g.

[0042] In one or more embodiments, Li 5 FeO 4 The quality and Li 5 FeO 4 The ratio of the total mass of the positive electrode active material is 0.1wt%-5wt%, preferably 0.5wt%-4wt%, more preferably 1wt%-3.5wt%, for example 1.5wt%-2.5wt%.

[0043] In one or more embodiments, the lithium supplement further comprises lithium nickelate (Li 2 NiO 2 ) and lithium oxalate (Li 2 C 2 O 4 ) or both.

[0044] In one or more embodiments, the lithium supplement further comprises Li 2 NiO 2 , Li 5 FeO 4 and Li 2 NiO 2 The mass ratio is preferably 1:(0.2-5), more preferably 1:(0.25-4).

[0045] In one or more embodiments, Li 2 NiO 2 The particle size D50 is 5-15μm.

[0046] In one or more embodiments, Li 2 NiO 2 The specific surface area is 0.1-1m 2 / g.

[0047] In one or more embodiments, the ratio of the mass of the lithium supplement agent to the total mass of the lithium supplement agent and the positive electrode active material is 0.1 wt % to 5 wt %.

[0048] In one or more embodiments, Li 5 FeO 4 The quality and Li 5 FeO 4 The ratio of the total mass of the positive electrode active material is P, the mass fraction of the unsaturated silane compound in the electrolyte is Q, P / Q≤30; preferably, P / Q≤25; more preferably, P / Q≤10; more preferably, P / Q≤5; more preferably, P / Q≤2.5.

[0049] In one or more embodiments, the electrolyte does not contain cyclic lithium borate compounds. Preferably, the cyclic lithium borate compounds include lithium difluorooxalatoborate, lithium difluoromalonateborate, lithium bisoxalatoborate and lithium difluorooxalatoborate.

[0050] Another aspect of the present invention provides an electric device, wherein the electric device comprises the secondary battery described in any one of the embodiments herein.

[0051] Another aspect of the present invention provides unsaturated silane compounds for improving the content of Li 5 FeO 4 The use of the present invention in improving the gas production, cycle performance, storage performance and / or dark lines on the negative electrode interface of a secondary battery.

[0052] In one or more embodiments, the unsaturated silane compound is as described in any embodiment herein.

[0053] In one or more embodiments, the secondary battery is as described in any of the embodiments herein.

[0054] The present invention has achieved the following beneficial effects: the present invention adds unsaturated silane compounds to the electrolyte to produce a multi-stage oxidation reaction, which can not only cause electron-loss oxidation reaction through the carbon-carbon double bond (oxygen free radical scavenging), but also combine with oxygen free radicals to form new organic silicon compounds (positive electrode film protection), thereby achieving the effects of inhibiting high-temperature storage and cycle gas production of lithium-supplemented system batteries, improving battery cell cycle performance and high-temperature storage performance, and improving dark lines on the negative electrode interface. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 This is a photo of the negative electrode sheet obtained after charging and disassembling the battery of Example 4.

[0056] Figure 2 This is a photo of the negative electrode sheet obtained after charging and disassembling the battery of Example 5.

[0057] Figure 3 This is a photo of the negative electrode sheet obtained after charging and disassembling the battery of Comparative Example 1. DETAILED DESCRIPTION

[0058] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in this document. Unless otherwise specified, all technical and scientific terms used in this document have the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definitions in this specification shall prevail.

[0059] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0060] Herein, “comprising”, “including”, “containing” and similar terms encompass the meanings of “consisting essentially of” and “consisting of”. For example, when “A comprises B and C” is disclosed herein, “A consists essentially of B and C” and “A consists of B and C” should be deemed to be disclosed herein.

[0061] In this article, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0062] In this document, unless otherwise specified, percentage refers to mass percentage and ratio refers to mass ratio.

[0063] Herein, the sum of the percentages of the various components of the composition is 100%.

[0064] Herein, when describing embodiments or examples, it should be understood that they are not used to limit the present invention to these embodiments or examples. On the contrary, all substitutes, modifications and equivalents of the methods and materials described in the present invention are all within the scope of the present invention.

[0065] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0066] use The present invention includes the use of unsaturated silane compounds in the electrolyte of secondary batteries. 5 FeO 4 The present invention includes the use of unsaturated silane compounds in improving the secondary battery containing Li 5 FeO 4 The invention relates to an application of the present invention in improving the gas production, cycle performance, storage performance and / or negative electrode interface dark lines of lithium-ion batteries. The secondary battery is preferably a lithium-ion battery. In the various uses provided by the present invention, the unsaturated silane compound can be as described in any embodiment of the present invention. In the various uses provided by the present invention, the electrolyte can be as described in any embodiment of the present invention. In the various uses provided by the present invention, the secondary battery can be as described in any embodiment of the present invention.

[0067] Unsaturated silane compounds In the present invention, the unsaturated silane compound refers to a compound formed by replacing the hydrogen atoms of silane with hydrocarbon groups, and at least one of the hydrocarbon groups serving as substituents is an unsaturated hydrocarbon group (eg, alkenyl, alkynyl).

[0068] In some embodiments, the unsaturated silane compound is a compound of formula I: ; In Formula I, R 1 , R 2 , R 3 , R 4 are each independently selected from C1-C4 alkyl, C2-C4 alkenyl and C2-C4 alkynyl, and R 1 , R 2 , R 3 , R 4 They are not C1-C4 alkyl at the same time.

[0069] In some preferred embodiments, R 1 , R 2 , R3 , R 4 Each is independently selected from C1-C4 alkyl and C2-C4 alkenyl. Exemplary C1-C4 alkyl includes methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl. Exemplary C2-C4 alkenyl includes vinyl, n-propenyl, n-allyl, 1-butenyl, 2-butenyl, isobutenyl, 3-methyl-1-propenyl.

[0070] In some preferred embodiments, R 1 , R 2 , R 3 , R 4 Each is independently selected from C1-C3 alkyl and C2-C3 alkenyl. Exemplary C1-C3 alkyl includes methyl, ethyl, n-propyl, isopropyl. Exemplary C2-C3 alkenyl includes vinyl, n-propenyl, n-allyl.

[0071] In some preferred embodiments, R 1 , R 2 , R 3 , R 4 Each is independently selected from methyl, ethyl, vinyl and allyl.

[0072] In some preferred embodiments, the unsaturated silane compound is selected from tetravinylsilane, vinyltrimethylsilane, divinyldimethylsilane, trivinylmethylsilane, allyltriethylsilane, diallyldiethylsilane, triallylethylsilane, and tetraallylsilane.

[0073] Electrolyte The electrolyte of the present invention comprises a lithium salt, a solvent and the unsaturated silane compound described in any embodiment of the present invention.

[0074] In some embodiments, the electrolyte of the present invention does not contain cyclic lithium borate compounds. The present invention finds that further adding cyclic lithium borate compounds (such as LiODFB) to the electrolyte containing unsaturated silane compounds will lead to an increase in cell impedance and deterioration in kinetics, thereby deteriorating the cycle life and high temperature storage performance of the cell, and the cyclic lithium borate compounds optimize Li 5 FeO 4 The gas production effect of the lithium supplement system is weak. Cyclic lithium borate compounds include lithium difluorooxalate borate, lithium difluoromalonate borate, lithium bisoxalate borate and lithium difluorooxalate borate.

[0075] In some embodiments, the lithium salt is selected from LiFSI, LiPF 6 、LiTFSI、LiBF 4 One or more of .

[0076] In some embodiments, the mass fraction of the lithium salt in the electrolyte is 6 wt%-20 wt%, for example 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, and 20 wt%.

[0077] In some embodiments, the solvent is selected from one or more of ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, propylene carbonate, diethyl carbonate, ethyl acetate, and ethyl propionate.

[0078] In some embodiments, the mass fraction of the unsaturated silane compound in the electrolyte is 0.001wt%-2wt%, preferably 0.01wt%-2wt%, 0.05wt%-2wt%, 0.1wt%-2wt%, for example 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.5wt%, 1.6wt%, 1.7wt%, 1.8wt%, 1.9wt%, 2wt%.

[0079] In some embodiments, the electrolyte further comprises an additive. The additive refers to other additives other than unsaturated silane compounds. The additive may include one or more of an alkane film-forming additive, a silicon-based phosphate film-forming additive, a silicon-based phosphite film-forming additive, a silicon-based borate film-forming additive, a sulfur-based additive, and a lithium salt additive. The alkane film-forming additive may be selected from one or more of vinylene carbonate, fluoroethylene carbonate, and vinyl ethylene carbonate. The silicon-based phosphate additive may be selected from one or more of tris(trimethylsilane) phosphate, tris(vinyldimethylsilane) phosphate, and diethyl trimethylsilyl phosphate. The silicon-based phosphite additive may be selected from one or more of tris(trimethylsilane) phosphite, tris(vinyldimethylsilane) phosphite, and diethyl trimethylsilyl phosphite. The silicon-based borate film-forming additive may be selected from one or more of tris(trimethylsilane) borate, tris(vinyldimethylsilane) borate, and diethyl trimethylsilyl borate. The sulfur additive may be selected from one or more of vinyl sulfate, vinyl sulfite, propenyl-1,3-sultone, methylene disulfonate, 1,3-propane sultone and 1,3-butane sultone. The lithium salt additive may be selected from LiPO 2 F 2 , LiODFP, LiODFB and LiOTFP. Preferably, the lithium salt additive does not include lithium borate compounds (such as LiODFB).

[0080] In some embodiments, the mass fraction of the additive in the electrolyte is 0.1 wt%-5 wt%, for example 0.1 wt%, 0.2 wt%, 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%.

[0081] Secondary battery The secondary battery of the present invention comprises a positive electrode plate, a negative electrode plate, an electrolyte and a separator. The electrolyte can be a semi-solid electrolyte or a liquid electrolyte. The liquid electrolyte is also called an electrolyte.

[0082] In some embodiments, the secondary battery of the present invention comprises a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator. In some embodiments, the secondary battery of the present invention is a lithium ion battery.

[0083] The electrolyte and the unsaturated silane compound in the secondary battery of the present invention are as described in any embodiment herein.

[0084] The positive electrode sheet includes a positive electrode current collector and a positive electrode material layer. In the present invention, the positive electrode material layer includes a positive electrode active material and a lithium supplement, and the lithium supplement includes Li 5 FeO 4 .

[0085] In the present invention, Li 5 FeO 4 The quality and Li 5 FeO 4 The ratio of the total mass of the positive electrode active material can be 0.1wt%-5wt%, preferably 0.5wt%-4wt%, more preferably 1wt%-3.5wt%, for example 1.5wt%-2.5wt%, for example 0.1wt%, 0.2wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%.

[0086] In the present invention, Li 5 FeO 4 The particle size D50 is preferably 5-10 μm, for example 6 μm, 7 μm, 8 μm, 8.5 μm, 8.7 μm, 9 μm. 5 FeO 4 The specific surface area is preferably 0.3-5m 2 / g, for example 0.5m 2 / g, 0.7m 2 / g, 0.8m 2 / g, 0.9m 2 / g, 1m 2 / g, 2m 2 / g, 3m2 / g, 4m 2 / g.

[0087] The positive electrode active material can be selected from one or more of lithium iron phosphate, lithium iron manganese phosphate, lithium manganate, nickel-cobalt-manganese ternary positive electrode material, nickel-cobalt-aluminum ternary positive electrode material and nickel-cobalt-manganese-aluminum quaternary positive electrode material.

[0088] In the present invention, the lithium supplement may optionally include a lithium removal agent. 5 FeO 4 Other lithium supplements other than lithium oxalate may include, for example, one or both of lithium nickelate and lithium oxalate.

[0089] In some embodiments, the lithium supplement further comprises Li 2 NiO 2 , Li 5 FeO 4 and Li 2 NiO 2 The mass ratio of is preferably 1:(0.2-5), more preferably 1:(0.25-4), for example 1:0.25, 1:0.5, 1:1, 1:2, 1:3, 1:4.

[0090] In the present invention, Li 2 NiO 2 The particle size D50 is preferably 5-15 μm, for example 6 μm, 8 μm, 10 μm, 12 μm, 14 μm, 14.5 μm, 14.8 μm. 2 NiO 2 The specific surface area is preferably 0.1-1m 2 / g, for example 0.2m 2 / g, 0.23m 2 / g, 0.25m 2 / g, 0.3m 2 / g, 0.5m 2 / g, 0.7m 2 / g, 0.9m 2 / g.

[0091] In the present invention, the ratio of the mass of the lithium supplement agent to the total mass of the lithium supplement agent and the positive electrode active material can be 0.1wt%-5wt%, for example 0.1wt%, 0.2wt%, 0.5wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%.

[0092] In the present invention, Li 5 FeO 4 The quality and Li 5 FeO 4The ratio of the total mass of the unsaturated silane compound to the total mass of the positive electrode active material is recorded as P, and the mass fraction of the unsaturated silane compound in the electrolyte is recorded as Q. P / Q is preferably ≤30, such as ≤25, ≤20, ≤15, ≤10, ≤8.4, ≤5, ≤3.2. The effect of reducing the dark lines on the negative electrode interface can be further achieved by controlling the P / Q ratio within the above range. More preferably, P / Q is controlled to ≤2.5, so that the effect of eliminating the dark lines on the negative electrode interface can be achieved.

[0093] The positive electrode material layer generally also includes a conductive agent and a binder. The positive electrode material layer is obtained by coating a positive electrode slurry containing a positive electrode active material, a conductive agent, a binder and a solvent onto a positive electrode current collector, and then drying and pressing. The positive electrode current collector may be an aluminum foil. The solvent of the positive electrode slurry may be N-methylpyrrolidone (NMP). The conductive agent of the positive electrode may be conductive carbon black (SP), and the binder may be polyvinylidene fluoride (PVDF). The mass ratio of each component in the positive electrode material layer may be conventional. For example, in the positive electrode material layer, the mass fraction of the positive electrode active material may be 90wt%-98wt%, the mass fraction of the conductive agent may be 0.5wt%-4wt%, and the mass fraction of the binder may be 0.5wt%-4wt%.

[0094] The negative electrode sheet includes a negative electrode current collector and a negative electrode material layer. The negative electrode current collector may be a copper foil. The negative electrode material layer includes a negative electrode active material. The negative electrode active material may include lithium metal, structured lithium metal, natural graphite, artificial graphite, mesophase carbon spheres, hard carbon, soft carbon, silicon, silicon-carbon composite materials, Li-Sn alloy, Li-Sn-O alloy, spinel structured lithiated TiO 2 -Li 4 Ti 5 O, Li-Al alloy or more.

[0095] The negative electrode material layer may also include one or both of a conductive agent and a binder. The conductive agent is used to improve the conductivity of the electrode. Conductive agents that can be used for the negative electrode include conductive carbon black, acetylene black, carbon nanotubes, carbon nanowires, carbon microspheres, carbon fibers, graphene, etc. The binder of the negative electrode is used to improve the bonding properties between the negative electrode active material particles and between the negative electrode active material particles and the current collector. Binders that can be used for the negative electrode include polyvinylidene fluoride, polytetrafluoroethylene, acrylonitrile multipolymers, polyacrylic acid (PAA), polyacrylic acid butyl, polyacrylonitrile, styrene-butadiene rubber (SBR), etc. The negative electrode material layer may also include a thickener, such as carboxymethyl cellulose (CMC). In some embodiments, the conductive agent in the negative electrode material layer is conductive carbon black, the binder is SBR, and the thickener is CMC. The mass ratio of each component in the negative electrode material layer can be conventional. For example, in the negative electrode material layer, the mass fraction of the negative electrode active material may be 90wt%-98wt%, the mass fraction of the conductive agent may be 0.5wt%-4wt%, the mass fraction of the binder may be 0.5wt%-4wt%, and the mass fraction of the thickener may be 1wt%-4wt%.

[0096] The negative electrode material layer is obtained by coating the negative electrode slurry containing the components of the negative electrode material layer and a solvent onto the negative electrode current collector, followed by drying and pressing. The solvent of the negative electrode slurry can be water.

[0097] The positive electrode sheet, the negative electrode sheet and the separator are stacked and / or wound so that the separator is between the positive electrode sheet and the negative electrode sheet, and then encapsulated in a shell. After drying, liquid injection (electrolyte injection), sealing, standing, forming, and capacity separation, a secondary battery, such as a lithium-ion battery, can be obtained.

[0098] Electrical devices The present invention also includes an electrical device containing the secondary battery of the present invention. In some embodiments, the secondary battery of the present invention can be used for, but is not limited to, the following electrical devices: laptop computers, pen-type computers, mobile computers, electronic book players, portable phones, portable fax machines, portable copiers, portable printers, head-mounted stereo headphones, video recorders, LCD televisions, portable cleaners, portable CD players, mini-discs, transceivers, electronic notepads, calculators, memory cards, portable recorders, radios, backup power supplies, motors, cars, motorcycles, power-assisted bicycles, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries, drones, and lithium ion capacitors.

[0099] The present invention will be described below in the form of specific examples. It should be understood that these examples are merely illustrative and are not intended to limit the scope of the present invention. The methods, reagents and materials used in the examples and comparative examples are, unless otherwise stated, conventional methods, reagents and materials in the art. The raw material compounds in the examples and comparative examples can all be purchased through commercial routes.

[0100] The gram capacity of the silicon-carbon composite material used in the embodiment is 1200 mAh / g, and the silicon content is 30 wt %.

[0101] Li used in the examples and comparative examples 5 FeO 4 The particle size D50 is 8.73 μm and the specific surface area is 0.786 m 2 / g (measured by BET method). Li used in the examples and comparative examples 2 NiO 2 The particle size D50 is 14.99 μm and the specific surface area is 0.230 m 2 / g (measured by BET method).

[0102] Electrolyte Preparation Example (1) Preparation of basic electrolyte 1 Lithium-ion battery electrolyte was prepared in a glove box (water content <0.01ppm, oxygen content <0.01ppm): first, ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were uniformly mixed in a mass ratio of 3:7, and 2wt% of film-forming additive vinylene carbonate (VC), 1wt% of film-forming additive fluoroethylene carbonate (FEC), 0.5wt% of vinyl sulfate (DTD), 7wt% LiFSI, and 7wt% LiPF were added thereto. 6 , and mix them evenly to obtain the required basic electrolyte 1. The mass percentage of the above-mentioned components is the ratio of the mass of the component to the total mass of the basic electrolyte.

[0103] (2) Preparation of basic electrolyte 2 Lithium-ion battery electrolyte was prepared in a glove box (water content <0.01ppm, oxygen content <0.01ppm): first, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) were uniformly mixed in a mass ratio of 3:3:4, and 2wt% of film-forming additive vinylene carbonate (VC), 1wt% of film-forming additive fluoroethylene carbonate (FEC), 0.5wt% of vinyl sulfate (DTD), 7wt% LiFSI, and 7wt% LiPF were added thereto. 6 , and mix evenly to obtain the required basic electrolyte 2, wherein the mass percentage of the aforementioned components is the ratio of the mass of the component to the total mass of the basic electrolyte.

[0104] (3) Preparation of basic electrolyte 3 Lithium-ion battery electrolyte was prepared in a glove box (water content <0.01ppm, oxygen content <0.01ppm): first, ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) were uniformly mixed in a mass ratio of 2.5:0.5:3:4, and 2wt% of film-forming additive vinylene carbonate (VC), 1wt% of film-forming additive fluoroethylene carbonate (FEC), 0.5wt% of vinyl sulfate (DTD), 7wt% LiFSI, and 7wt% LiPF were added thereto. 6 , and the required basic electrolyte 3 is obtained after uniform mixing. The mass percentage of the above-mentioned components is the ratio of the mass of the component to the total mass of the basic electrolyte.

[0105] (4) Preparation of basic electrolyte 4 Lithium-ion battery electrolyte was prepared in a glove box (water content <0.01ppm, oxygen content <0.01ppm): first, ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were uniformly mixed in a mass ratio of 3:7, and 2wt% of film-forming additive vinylene carbonate (VC), 1wt% of film-forming additive fluoroethylene carbonate (FEC), 0.5wt% of vinyl sulfate (DTD), and 13.8wt% of LiFSI were added thereto, and the required basic electrolyte 4 was obtained after mixing evenly. The mass percentage of the aforementioned components is the ratio of the mass of the component to the total mass of the basic electrolyte.

[0106] (5) Preparation of basic electrolyte 5 Lithium-ion battery electrolyte was prepared in a glove box (water content <0.01ppm, oxygen content <0.01ppm): first, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) were uniformly mixed in a mass ratio of 3:3:4, and 2wt% of film-forming additive vinylene carbonate (VC), 1wt% of film-forming additive fluoroethylene carbonate (FEC), 0.5wt% of vinyl sulfate (DTD), and 12.5wt% of LiPF were added thereto. 6 , and the required basic electrolyte 5 is obtained after uniform mixing. The mass percentage of the aforementioned components is the ratio of the mass of the component to the total mass of the basic electrolyte.

[0107] (6) Preparation of basic electrolyte 6 Lithium-ion battery electrolyte was prepared in a glove box (water content <0.01ppm, oxygen content <0.01ppm): first, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) were uniformly mixed in a mass ratio of 3:3:4, and 2wt% of film-forming additive vinylene carbonate (VC), 1wt% of film-forming additive fluoroethylene carbonate (FEC), 0.5wt% of vinyl sulfate (DTD), 0.25wt% of tris(trimethylsilyl) phosphate (TMSP), and 0.25wt% of LiPO were added thereto. 2 F 2 、7wt%LiFSI、7wt%LiPF 6 , and mixed evenly to obtain the required basic electrolyte 6, wherein the mass percentage of the aforementioned components is the ratio of the mass of the component to the total mass of the basic electrolyte.

[0108] (7) Preparation of basic electrolyte 7 Lithium-ion battery electrolyte was prepared in a glove box (water content <0.01ppm, oxygen content <0.01ppm): first, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) were uniformly mixed in a mass ratio of 3:3:4, and 2wt% of film-forming additive vinylene carbonate (VC), 1wt% of film-forming additive fluoroethylene carbonate (FEC), 0.5wt% of methylene disulfonate (MMDS), 0.25wt% TMSP, and 0.25wt% LiPO were added thereto. 2 F 2 、7wt%LiFSI、7wt%LiPF 6 , and mixed evenly to obtain the required basic electrolyte 7, wherein the mass percentage of the aforementioned components is the ratio of the mass of the component to the total mass of the basic electrolyte.

[0109] (8) Preparation of basic electrolyte 8 Lithium-ion battery electrolyte was prepared in a glove box (water content <0.01ppm, oxygen content <0.01ppm): first, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) were uniformly mixed in a mass ratio of 3:3:4, and 2wt% of film-forming additive vinylene carbonate (VC), 1wt% of film-forming additive fluoroethylene carbonate (FEC), 0.5wt% MMDS, 0.25wt% TMSP, 0.25wt% LiODFB, 7wt% LiFSI, and 7wt% LiPF were added thereto. 6 , and the required basic electrolyte 8 is obtained after uniform mixing. The mass percentage of the above-mentioned components is the ratio of the mass of the component to the total mass of the basic electrolyte.

[0110] (9) Preparation of basic electrolyte 9 Lithium-ion battery electrolyte was prepared in a glove box (water content <0.01ppm, oxygen content <0.01ppm): first, ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were uniformly mixed in a mass ratio of 3:7, and 2wt% of film-forming additive vinylene carbonate (VC), 1wt% of film-forming additive fluoroethylene carbonate (FEC), 7wt% LiFSI, and 7wt% LiPF were added thereto. 6 , and the required basic electrolyte 9 is obtained after uniform mixing. The mass percentage of the above-mentioned components is the ratio of the mass of the component to the total mass of the basic electrolyte.

[0111] Example 1 Preparation of the electrolyte used in Example 1: Prepare a lithium-ion battery electrolyte in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and mix 99.9 wt % of the basic electrolyte 1 and 0.1 wt % of tetravinylsilane (TVSI for short, CAS: 1112-55-6) to obtain the desired electrolyte.

[0112] The preparation process of the battery of Example 1 is as follows: (1) Preparation of positive electrode: Dissolve 190g of PVDF powder in 2531g of NMP and stir evenly to obtain a PVDF gel solution with a solid content of 7wt% for use. 5 FeO 4 The PVDF glue prepared above was added to the mixed dry materials, stirred evenly, and then the slurry was adjusted to a suitable coating viscosity and solid content, and then coated on both sides of a 13 μm thick aluminum foil current collector. After drying and compaction, a positive electrode sheet was obtained. The single-sided surface density of the positive electrode material layer on the positive electrode sheet was 17.97 mg / cm 2 , compacted density is 2.55g / cm 3 .

[0113] (2) Preparation of negative electrode: 72g of CMC powder was dissolved in 3928g of deionized water to prepare a slurry with a solid content of 1.8wt% for use. 5kg of artificial graphite and 0.17kg of conductive carbon black (SP) were mixed and stirred evenly, and then appropriate amounts of CMC slurry (solid content 1.8wt%) and SBR slurry (solid content 40wt%) were added to make the composition of the negative electrode material layer meet 96.2wt% graphite + 1.2wt% SP + 0.6wt% CMC + 2wt% SBR. After stirring evenly, the slurry was adjusted to a suitable coating viscosity and solid content, and then coated on both sides of a 6μm thick copper foil current collector. After drying and compaction, a negative electrode sheet was obtained. The single-sided surface density of the negative electrode material layer on the negative electrode sheet was 9.22 mg / cm 2 , compacted density is 1.55g / cm3 .

[0114] (3) The positive and negative electrode sheets are sequentially subjected to die-cutting, drying, winding, assembly, primary liquid injection (injection of electrolyte), primary sealing, formation, and capacity separation to obtain a 4060D0-2.0Ah square soft-pack lithium-ion battery.

[0115] Example 2 Preparation of the electrolyte used in Example 2: Prepare the lithium-ion battery electrolyte in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and mix 99.7 wt % of the basic electrolyte 1 and 0.3 wt % of tetravinylsilane (TVSI) to obtain the desired electrolyte.

[0116] The preparation process of the battery of Example 2 is the same as that of Example 1.

[0117] The battery of Example 2 is different from that of Example 1 only in the electrolyte.

[0118] Example 3 Preparation of the electrolyte used in Example 3: Prepare the lithium-ion battery electrolyte in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and mix 99.5 wt % of the basic electrolyte 1 and 0.5 wt % of tetravinylsilane (TVSI) to obtain the desired electrolyte.

[0119] The preparation process of the battery of Example 3 is the same as that of Example 1.

[0120] The battery of Example 3 is different from that of Example 1 only in the electrolyte.

[0121] Example 4 Preparation of the electrolyte used in Example 4: Prepare the lithium-ion battery electrolyte in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and mix 99.2 wt % of the basic electrolyte 1 and 0.8 wt % of tetravinylsilane (TVSI) to obtain the desired electrolyte.

[0122] The preparation process of the battery of Example 4 is the same as that of Example 1.

[0123] The battery of Example 4 is different from that of Example 1 only in the electrolyte.

[0124] Example 5 Preparation of the electrolyte used in Example 5: Prepare the lithium-ion battery electrolyte in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and mix 99.0 wt % of the basic electrolyte 1 and 1.0 wt % of tetravinylsilane (TVSI) to obtain the desired electrolyte.

[0125] The preparation process of the battery of Example 5 is the same as that of Example 1.

[0126] The battery of Example 5 is different from that of Example 1 only in the electrolyte.

[0127] Example 6 Preparation of the electrolyte used in Example 6: Prepare the lithium-ion battery electrolyte in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and mix 98.5 wt % of the basic electrolyte 1 and 1.5 wt % of tetravinylsilane (TVSI) to obtain the desired electrolyte.

[0128] The preparation process of the battery of Example 6 is the same as that of Example 1.

[0129] The battery of Example 6 differs from that of Example 1 only in the electrolyte.

[0130] Example 7 Preparation of the electrolyte used in Example 7: Lithium-ion battery electrolyte was prepared in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and 98.0 wt % of basic electrolyte 1 and 2.0 wt % of tetravinylsilane (TVSI) were mixed evenly to obtain the desired electrolyte.

[0131] The preparation process of the battery of Example 7 is the same as that of Example 1.

[0132] The battery of Example 7 is different from that of Example 1 only in the electrolyte.

[0133] Example 8 Preparation of the electrolyte used in Example 8: Prepare the lithium-ion battery electrolyte in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and mix 99.0 wt % of the basic electrolyte 1 and 1.0 wt % of tetravinylsilane (TVSI) to obtain the desired electrolyte.

[0134] The preparation process of the battery of Example 8 is as follows: (1) Preparation of positive electrode: Dissolve 190g of PVDF powder in 2531g of NMP and stir evenly to obtain a PVDF gel solution with a solid content of 7wt% for use. 5 FeO 4 The PVDF glue prepared above was added to the mixed dry materials, stirred evenly, and then the slurry was adjusted to a suitable coating viscosity and solid content, and then coated on both sides of a 13 μm thick aluminum foil current collector. After drying and compaction, a positive electrode sheet was obtained. The single-sided surface density of the positive electrode material layer on the positive electrode sheet was 20.00 mg / cm 2, compacted density is 2.20g / cm 3 .

[0135] (2) Preparation of negative electrode: 72g of CMC powder was dissolved in 3928g of deionized water to prepare a slurry with a solid content of 1.8wt% for use. 5kg of artificial graphite and 0.17kg of conductive carbon black (SP) were dry-mixed and stirred evenly, and then appropriate amounts of CMC slurry (solid content 1.8wt%) and SBR slurry (solid content 40wt%) were added to make the composition of the negative electrode material layer meet 96.2wt% graphite + 1.2wt% SP + 0.6wt% CMC + 2wt% SBR. After stirring evenly, the slurry was adjusted to a suitable coating viscosity and solid content, and then coated on both sides of a 6μm thick copper foil current collector. After drying and compaction, a negative electrode sheet was obtained. The single-sided surface density of the negative electrode material layer on the negative electrode sheet was 9.60 mg / cm 2 , compacted density is 1.55g / cm 3 .

[0136] (3) The positive and negative electrode sheets are sequentially subjected to die-cutting, drying, winding, assembly, primary liquid injection (injection of electrolyte), primary sealing, formation, and capacity separation to obtain a 4060D0-2.0Ah square soft-pack lithium-ion battery.

[0137] Example 9 Preparation of the electrolyte used in Example 9: Prepare the lithium-ion battery electrolyte in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and mix 99.0 wt % of the basic electrolyte 1 and 1.0 wt % of tetravinylsilane (TVSI) to obtain the desired electrolyte.

[0138] The preparation process of the battery of Example 9 is as follows: (1) Preparation of positive electrode: Dissolve 190g of PVDF powder in 2531g of NMP and stir evenly to obtain a PVDF gel solution with a solid content of 7wt% for use. 5 FeO 4 The PVDF glue prepared above was added to the mixed dry materials, stirred evenly, and then the slurry was adjusted to a suitable coating viscosity and solid content, and then coated on both sides of a 13 μm thick aluminum foil current collector. After drying and compaction, a positive electrode sheet was obtained. The single-sided surface density of the positive electrode material layer on the positive electrode sheet was 15.00 mg / cm 2 , compacted density is 2.80g / cm 3 .

[0139] (2) Preparation of negative electrode: 72g of CMC powder was dissolved in 3928g of deionized water to prepare a 1.8wt% solid content glue for use. 5kg of artificial graphite and 0.17kg of conductive carbon black (SP) were mixed and stirred evenly, and then appropriate amounts of CMC glue (solid content 1.8wt%) and SBR glue (solid content 40wt%) were added to make the composition of the negative electrode material layer meet 96.2wt% graphite + 1.2wt% SP + 0.6wt% CMC + 2wt% SBR. After stirring evenly, the slurry was adjusted to a suitable coating viscosity and solid content, and then coated on both sides of a 6μm thick copper foil current collector. After drying and compaction, a negative electrode sheet was obtained. The single-sided surface density of the negative electrode material layer on the negative electrode sheet was 10.30 mg / cm 2 , compacted density is 1.55g / cm 3 .

[0140] (3) The positive and negative electrode sheets are sequentially subjected to die-cutting, drying, winding, assembly, primary liquid injection (injection of electrolyte), primary sealing, formation, and capacity separation to obtain a 4060D0-2.0Ah square soft-pack lithium-ion battery.

[0141] Example 10 Preparation of the electrolyte used in Example 10: Prepare the lithium-ion battery electrolyte in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and mix 99.0 wt % of the basic electrolyte 1 and 1.0 wt % of tetravinylsilane (TVSI) to obtain the desired electrolyte.

[0142] The preparation process of the battery of Example 10 is as follows: (1) Preparation of positive electrode: Dissolve 190g of PVDF powder in 2531g of NMP and stir evenly to obtain a PVDF gel solution with a solid content of 7wt% for use. 5 FeO 4 The PVDF glue prepared above was added to the mixed dry materials, stirred evenly, and then the slurry was adjusted to a suitable coating viscosity and solid content, and then coated on both sides of a 13 μm thick aluminum foil current collector. After drying and compaction, a positive electrode sheet was obtained. The single-sided surface density of the positive electrode material layer on the positive electrode sheet was 17.00 mg / cm 2 , compacted density is 3.20g / cm 3 .

[0143] (2) Preparation of negative electrode: 72g of CMC powder was dissolved in 3928g of deionized water to prepare a slurry with a solid content of 1.8wt% for use. 5kg of artificial graphite and 0.17kg of conductive carbon black (SP) were mixed and stirred evenly, and then appropriate amounts of CMC slurry (solid content 1.8wt%) and SBR slurry (solid content 40wt%) were added to make the composition of the negative electrode material layer meet 96.2wt% graphite + 1.2wt% SP + 0.6wt% CMC + 2wt% SBR. After stirring evenly, the slurry was adjusted to a suitable coating viscosity and solid content, and then coated on both sides of a 6μm thick copper foil current collector. After drying and compaction, a negative electrode sheet was obtained. The single-sided surface density of the negative electrode material layer on the negative electrode sheet was 10.20 mg / cm 2 , compacted density is 1.55g / cm 3 .

[0144] (3) The positive and negative electrode sheets are sequentially subjected to die-cutting, drying, winding, assembly, primary liquid injection (injection of electrolyte), primary sealing, formation, and capacity separation to obtain a 4060D0-2.0Ah square soft-pack lithium-ion battery.

[0145] Embodiment 11 Preparation of the electrolyte used in Example 11: Prepare the lithium-ion battery electrolyte in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and mix 99.0 wt % of the basic electrolyte 1 and 1.0 wt % of tetravinylsilane (TVSI) to obtain the desired electrolyte.

[0146] The preparation process of the battery of Example 11 is as follows: (1) Preparation of positive electrode: Dissolve 190g of PVDF powder in 2531g of NMP and stir evenly to obtain a PVDF gel solution with a solid content of 7wt% for use. 5 FeO 4 The PVDF glue prepared above was added to the mixed dry materials, stirred evenly, and then the slurry was adjusted to a suitable coating viscosity and solid content, and then coated on both sides of a 13 μm thick aluminum foil current collector. After drying and compaction, a positive electrode sheet was obtained. The single-sided surface density of the positive electrode material layer on the positive electrode sheet was 15.00 mg / cm 2 , compacted density is 2.80g / cm 3 .

[0147] (2) Preparation of negative electrode: 72g of CMC powder was dissolved in 3928g of deionized water to prepare a slurry with a solid content of 1.8wt% for use. 4.35kg of artificial graphite, 0.65kg of silicon carbon and 0.17kg of conductive carbon black (SP) were mixed and stirred evenly, and then appropriate amounts of CMC slurry (solid content 1.8wt%) and SBR slurry (solid content 40wt%) were added to make the composition of the negative electrode material layer meet 83.7wt% graphite + 12.5wt% silicon carbon + 1.2wt% SP + 0.6wt% CMC + 2wt% SBR. After stirring evenly, the slurry was adjusted to a suitable coating viscosity and solid content, and then coated on both sides of a 6μm thick copper foil current collector. After drying and compaction, a negative electrode sheet was obtained. The single-sided surface density of the negative electrode material layer on the negative electrode sheet was 7.75 mg / cm 2 , compacted density is 1.55g / cm 3 .

[0148] (3) The positive and negative electrode sheets are sequentially subjected to die-cutting, drying, winding, assembly, primary liquid injection (injection of electrolyte), primary sealing, formation, and capacity separation to obtain a 4060D0-2.0Ah square soft-pack lithium-ion battery.

[0149] Example 12 Preparation of the electrolyte used in Example 12: Prepare the lithium-ion battery electrolyte in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and mix 99.0 wt % of the basic electrolyte 1 and 1.0 wt % of tetravinylsilane (TVSI) to obtain the desired electrolyte.

[0150] The preparation process of the battery of Example 12 is basically the same as that of Example 1, except that: in the preparation of the positive electrode, 10 kg lithium iron phosphate + 0.265 kg Li 5 FeO 4 Replaced with 10kg lithium iron phosphate + 0.212kg lithium nickel oxide + 0.053kg Li 5 FeO 4 .

[0151] Example 13 Preparation of the electrolyte used in Example 13: Prepare the lithium-ion battery electrolyte in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and mix 99.0 wt % of the basic electrolyte 1 and 1.0 wt % of tetravinylsilane (TVSI) to obtain the desired electrolyte.

[0152] The preparation process of the battery of Example 13 is basically the same as that of Example 1, except that: in the preparation of the positive electrode, 10 kg lithium iron phosphate + 0.265 kg Li 5 FeO 4Replaced with 9.894kg lithium iron phosphate + 0.317kg lithium nickel oxide + 0.053kg Li 5 FeO 4 .

[0153] Embodiment 14 Preparation of the electrolyte used in Example 14: Prepare the lithium-ion battery electrolyte in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and mix 99.0 wt % of the basic electrolyte 1 and 1.0 wt % of tetravinylsilane (TVSI) to obtain the desired electrolyte.

[0154] The preparation process of the battery of Example 14 is basically the same as that of Example 1, except that: in the preparation of the positive electrode, 10 kg lithium iron phosphate + 0.265 kg Li 5 FeO 4 Replaced with 9.788kg lithium iron phosphate + 0.423kg lithium nickel oxide + 0.053kgLi 5 FeO 4 .

[0155] Embodiment 15 Preparation of the electrolyte used in Example 15: Prepare the lithium-ion battery electrolyte in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and mix 99.0 wt % of the basic electrolyte 1 and 1.0 wt % of tetravinylsilane (TVSI) to obtain the desired electrolyte.

[0156] The preparation process of the battery of Example 15 is basically the same as that of Example 1, except that: in the preparation of the positive electrode, 10 kg lithium iron phosphate + 0.265 kg Li 5 FeO 4 Replaced with 10kg lithium iron phosphate + 0.106kg lithium nickel oxide + 0.159kg Li 5 FeO 4 .

[0157] Example 16 Preparation of the electrolyte used in Example 16: Prepare the lithium-ion battery electrolyte in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and mix 99.0 wt % of the basic electrolyte 1 and 1.0 wt % of tetravinylsilane (TVSI) to obtain the desired electrolyte.

[0158] The preparation process of the battery of Example 16 is basically the same as that of Example 1, except that: in the preparation of the positive electrode, 10 kg lithium iron phosphate + 0.265 kg Li 5 FeO 4 Replaced with 10kg lithium iron phosphate + 0.053kg lithium nickel oxide + 0.212kg Li5 FeO 4 。

[0159] Example 17 Preparation of the electrolyte used in Example 17: In a glove box (with moisture < 0.01 ppm and oxygen content < 0.01 ppm), prepare the lithium-ion battery electrolyte by mixing 99.0 wt% of basic electrolyte 1 and 1.0 wt% of tetravinylsilane (TVSI) uniformly to obtain the required electrolyte.

[0160] The preparation process of the battery in Example 17 is basically the same as that in Example 1, with the only difference being that in the preparation of the positive electrode, 10 kg of lithium iron phosphate + 0.265 kg of Li 5 FeO 4 is replaced with 10.212 kg of lithium iron phosphate + 0.053 kg of Li 5 FeO 4 。

[0161] Example 18 Preparation of the electrolyte used in Example 18: In a glove box (with moisture < 0.01 ppm and oxygen content < 0.01 ppm), prepare the lithium-ion battery electrolyte by mixing 99.0 wt% of basic electrolyte 1 and 1.0 wt% of tetravinylsilane (TVSI) uniformly to obtain the required electrolyte.

[0162] The preparation process of the battery in Example 18 is basically the same as that in Example 1, with the only difference being that in the preparation of the positive electrode, 10 kg of lithium iron phosphate + 0.265 kg of Li 5 FeO 4 is replaced with 10.159 kg of lithium iron phosphate + 0.106 kg of Li 5 FeO 4 。

[0163] Example 19 Preparation of the electrolyte used in Example 19: In a glove box (with moisture < 0.01 ppm and oxygen content < 0.01 ppm), prepare the lithium-ion battery electrolyte by mixing 99.0 wt% of basic electrolyte 1 and 1.0 wt% of tetravinylsilane (TVSI) uniformly to obtain the required electrolyte.

[0164] The preparation process of the battery in Example 19 is basically the same as that in Example 1, with the only difference being that in the preparation of the positive electrode, 10 kg of lithium iron phosphate + 0.265 kg of Li 5 FeO 4 is replaced with 9.894 kg of lithium iron phosphate + 0.370 kg of Li 5 FeO 4 。

[0165] Example 20 Preparation of the electrolyte used in Example 20: Prepare the lithium-ion battery electrolyte in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and mix 99.0 wt % of the basic electrolyte 1 and 1.0 wt % of tetravinylsilane (TVSI) to obtain the desired electrolyte.

[0166] The preparation process of the battery of Example 20 is basically the same as that of Example 1, except that: in the preparation of the positive electrode, 10 kg lithium iron phosphate + 0.265 kg Li 5 FeO 4 Replaced with 9.841kg lithium iron phosphate + 0.423kg Li 5 FeO 4 .

[0167] Embodiment 21 Preparation of the electrolyte used in Example 21: Prepare the lithium-ion battery electrolyte in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and mix 99.0 wt % of the basic electrolyte 2 and 1.0 wt % of tetravinylsilane (TVSI) to obtain the desired electrolyte.

[0168] The preparation process of the battery of Example 21 is the same as that of Example 1.

[0169] The battery of Example 21 differs from that of Example 1 only in the electrolyte.

[0170] Embodiment 22 Preparation of the electrolyte used in Example 22: Prepare the lithium-ion battery electrolyte in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and mix 99.0 wt % of the basic electrolyte 3 and 1.0 wt % of tetravinylsilane (TVSI) to obtain the desired electrolyte.

[0171] The preparation process of the battery of Example 22 is the same as that of Example 1.

[0172] The battery of Example 22 differs from that of Example 1 only in the electrolyte.

[0173] Embodiment 23 Preparation of the electrolyte used in Example 23: Prepare the lithium-ion battery electrolyte in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and mix 99.0 wt % of the basic electrolyte 4 and 1.0 wt % of tetravinylsilane (TVSI) to obtain the desired electrolyte.

[0174] The preparation process of the battery of Example 23 is the same as that of Example 1.

[0175] The battery of Example 23 differs from that of Example 1 only in the electrolyte.

[0176] Embodiment 24 Preparation of the electrolyte used in Example 24: Prepare the lithium-ion battery electrolyte in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and mix 99.0 wt % of the basic electrolyte 5 and 1.0 wt % of tetravinylsilane (TVSI) to obtain the desired electrolyte.

[0177] The preparation process of the battery of Example 24 is the same as that of Example 1.

[0178] The battery of Example 24 differs from that of Example 1 only in the electrolyte.

[0179] Embodiment 25 Preparation of the electrolyte used in Example 25: Prepare the lithium-ion battery electrolyte in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and mix 99.0 wt % of the basic electrolyte 6 and 1.0 wt % of tetravinylsilane (TVSI) to obtain the desired electrolyte.

[0180] The preparation process of the battery of Example 25 is the same as that of Example 1.

[0181] The battery of Example 25 differs from that of Example 1 only in the electrolyte.

[0182] Embodiment 26 Preparation of the electrolyte used in Example 26: Prepare the lithium-ion battery electrolyte in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and mix 99.0 wt % of the basic electrolyte 7 and 1.0 wt % of tetravinylsilane (TVSI) to obtain the desired electrolyte.

[0183] The preparation process of the battery of Example 26 is the same as that of Example 1.

[0184] The battery of Example 26 differs from that of Example 1 only in the electrolyte. Example

[0185] Preparation of the electrolyte used in Example 27: Prepare the lithium-ion battery electrolyte in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and mix 99.0 wt % of the basic electrolyte 8 and 1.0 wt % of tetravinylsilane (TVSI) to obtain the desired electrolyte.

[0186] The preparation process of the battery of Example 27 is the same as that of Example 1.

[0187] The battery of Example 27 differs from that of Example 1 only in the electrolyte.

[0188] Embodiment 28 Preparation of the electrolyte used in Example 28: Prepare the lithium-ion battery electrolyte in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and mix 99.0 wt % of the basic electrolyte 9 and 1.0 wt % of tetravinylsilane (TVSI) to obtain the desired electrolyte.

[0189] The preparation process of the battery of Example 28 is the same as that of Example 1.

[0190] The battery of Example 28 differs from that of Example 1 only in the electrolyte.

[0191] Embodiment 29 Preparation of the electrolyte used in Example 29: Prepare the lithium-ion battery electrolyte in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and mix 99.0 wt % of the basic electrolyte 1 and 1.0 wt % of vinyltrimethylsilane (CAS: 754-05-2) to obtain the desired electrolyte.

[0192] The preparation process of the battery of Example 29 is the same as that of Example 1.

[0193] The battery of Example 29 differs from that of Example 1 only in the electrolyte.

[0194] Embodiment 30 Preparation of the electrolyte used in Example 30: Prepare the lithium-ion battery electrolyte in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and mix 99.0 wt % of the basic electrolyte 1 and 1.0 wt % of divinyldimethylsilane (CAS: 10519-87-6) to obtain the desired electrolyte.

[0195] The preparation process of the battery of Example 30 is the same as that of Example 1.

[0196] The battery of Example 30 differs from that of Example 1 only in the electrolyte.

[0197] Embodiment 31 Preparation of the electrolyte used in Example 31: Prepare the lithium-ion battery electrolyte in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and mix 99.0 wt % of the basic electrolyte 1 and 1.0 wt % of trivinylmethylsilane (CAS: 18244-95-6) to obtain the desired electrolyte.

[0198] The preparation process of the battery of Example 31 is the same as that of Example 1.

[0199] The battery of Example 31 differs from that of Example 1 only in the electrolyte.

[0200] Embodiment 32 Preparation of the electrolyte used in Example 32: Prepare the lithium-ion battery electrolyte in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and mix 99.0 wt % of the basic electrolyte 1 and 1.0 wt % of allyltriethylsilane (CAS: 17898-21-4) to obtain the desired electrolyte.

[0201] The preparation process of the battery of Example 32 is the same as that of Example 1.

[0202] The battery of Example 32 differs from that of Example 1 only in the electrolyte.

[0203] Embodiment 33 Preparation of the electrolyte used in Example 33: Prepare the lithium-ion battery electrolyte in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and mix 99.0 wt % of the basic electrolyte 1 and 1.0 wt % of diallyldiethylsilane (CAS: 2186-42-7) to obtain the desired electrolyte.

[0204] The preparation process of the battery of Example 33 is the same as that of Example 1.

[0205] The battery of Example 33 differs from that of Example 1 only in the electrolyte.

[0206] Embodiment 34 Preparation of the electrolyte used in Example 34: Prepare the lithium-ion battery electrolyte in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and mix 99.0 wt % of the basic electrolyte 1 and 1.0 wt % of triallylethylsilane (CAS: 17963-25-6) to obtain the desired electrolyte.

[0207] The preparation process of the battery of Example 34 is the same as that of Example 1.

[0208] The battery of Example 34 differs from that of Example 1 only in the electrolyte.

[0209] Embodiment 35 Preparation of the electrolyte used in Example 35: Prepare the lithium-ion battery electrolyte in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and mix 99.0 wt % of the basic electrolyte 1 and 1.0 wt % of tetraallylsilane (CAS: 1112-66-9) to obtain the desired electrolyte.

[0210] The preparation process of the battery of Example 35 is the same as that of Example 1.

[0211] The battery of Example 35 differs from that of Example 1 only in the electrolyte.

[0212] Embodiment 36 Preparation of the electrolyte used in Example 36: Lithium-ion battery electrolyte was prepared in a glove box (water content <0.01ppm, oxygen content <0.01ppm): first, ethylene carbonate (EC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) were uniformly mixed in a mass ratio of 30:45:15, and 0.5wt% of film-forming additive fluoroethylene carbonate (FEC), 2.5wt% of film-forming additive vinylene carbonate (VC), 0.5wt% of methylene disulfonate (MMDS), 0.2wt% of tetravinylsilane (TVSI), 3wt% LiFSI, and 5wt% LiPF were added thereto. 6 , and the desired electrolyte is obtained after uniform mixing. The mass percentage of the aforementioned components is the ratio of the mass of the component to the total mass of the electrolyte.

[0213] The preparation process of the battery of Example 36 is as follows: (1) Preparation of positive electrode: Dissolve 190g of PVDF powder in 2531g of NMP and stir evenly to obtain a PVDF gel solution with a solid content of 7wt% for use. 5 FeO 4 The conductive carbon black (SP) and the dry materials are mixed and stirred evenly, and then the PVDF glue prepared above is added to the mixed dry materials so that the composition of the positive electrode material layer meets 96.9wt% lithium iron phosphate + 0.5wt% Li 5 FeO 4 +0.8wt%SP+1.8wt%PVDF, stir evenly and adjust the slurry to a suitable coating viscosity and solid content, then double-sidedly coat it on a 13μm thick aluminum foil current collector, dry and compact to obtain a positive electrode sheet. The single-sided surface density of the positive electrode material layer on the positive electrode sheet is 19.67mg / cm 2 , compacted density is 2.6g / cm 3 .

[0214] (2) Preparation of negative electrode: 72g of CMC powder was dissolved in 3928g of deionized water to prepare a slurry with a solid content of 1.8wt%. Graphite and conductive carbon black (SP) were mixed and stirred evenly, and then appropriate amounts of CMC slurry (solid content 1.8wt%), SBR slurry (solid content 40wt%) and PAA slurry (solid content 6wt%) were added to make the composition of the negative electrode material layer meet 96.2wt% graphite + 1.2wt% SP + 0.6wt% CMC + 1.2wt% SBR + 0.8wt% PAA. After stirring evenly, the slurry was adjusted to a suitable coating viscosity and solid content, and then coated on both sides of a 6μm thick copper foil current collector. After drying and compaction, a negative electrode sheet was obtained. The single-sided surface density of the negative electrode material layer on the negative electrode sheet was 9.87mg / cm 2 , compacted density is 1.61g / cm 3 .

[0215] (3) The positive and negative electrode sheets are sequentially subjected to die-cutting, drying, winding, assembly, primary liquid injection (injection of electrolyte), primary sealing, formation, and capacity separation to obtain a 4060D0-2.0Ah square soft-pack lithium-ion battery.

[0216] Comparative Example 1 The electrolyte used in Comparative Example 1 is Basic Electrolyte 1.

[0217] The preparation process of the battery of Comparative Example 1 is the same as that of Example 1.

[0218] The battery of Comparative Example 1 is different from that of Example 1 only in the electrolyte.

[0219] Comparative Example 2 Preparation of the electrolyte used in Comparative Example 2: Lithium-ion battery electrolyte was prepared in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and 99.0 wt % of basic electrolyte 1 and 1.0 wt % of tetravinylsilane (TVSI) were mixed uniformly to obtain the desired electrolyte.

[0220] The preparation process of the battery in Comparative Example 2 is basically the same as that in Example 1, except that: in the preparation of the positive electrode, 10 kg lithium iron phosphate + 0.265 kg Li 5 FeO 4 Replaced with 10.256kg lithium iron phosphate.

[0221] Comparative Example 3 The electrolyte used in Comparative Example 3 is Basic Electrolyte 1.

[0222] The preparation process of the battery in Comparative Example 3 is basically the same as that in Example 1, except that: in the preparation of the positive electrode, 10 kg lithium iron phosphate + 0.265 kg Li 5 FeO4 Replaced with 10.256kg lithium iron phosphate.

[0223] Comparative Example 4 The electrolyte used in Comparative Example 4 is Basic Electrolyte 1.

[0224] The preparation process of the battery of Comparative Example 4 is the same as that of Example 8.

[0225] Comparative Example 5 The electrolyte used in Comparative Example 5 is Basic Electrolyte 1.

[0226] The preparation process of the battery of Comparative Example 5 is the same as that of Example 9.

[0227] Comparative Example 6 The electrolyte used in Comparative Example 6 is Basic Electrolyte 1.

[0228] The preparation process of the battery of Comparative Example 6 is the same as that of Example 10.

[0229] Comparative Example 7 The electrolyte used in Comparative Example 7 is Basic Electrolyte 1.

[0230] The preparation process of the battery of Comparative Example 7 is the same as that of Example 11.

[0231] Comparative Example 8 Preparation of the electrolyte used in Comparative Example 8: Lithium-ion battery electrolyte was prepared in a glove box (water content <0.01 ppm, oxygen content <0.01 ppm), and 97.0 wt % of basic electrolyte 1, 1.0 wt % of tetravinylsilane (TVSI), and 2.0 wt % of LiODFB were mixed uniformly to obtain the desired electrolyte.

[0232] The preparation process of the battery of Comparative Example 8 is the same as that of Example 1.

[0233] The battery of Comparative Example 8 is different from that of Example 1 only in the electrolyte.

[0234] Comparative Example 9 The electrolyte used in Comparative Example 9 differs from the electrolyte used in Example 36 only in that the electrolyte used in Comparative Example 9 does not contain TVSI.

[0235] The preparation process of the battery of Comparative Example 9 is the same as that of Example 36.

[0236] The battery of Comparative Example 9 differs from that of Example 36 only in the electrolyte.

[0237] Test Example 1 The following tests were performed on the batteries of Examples 1-35 and Comparative Examples 1-8. The results are shown in Table 1.

[0238] 1. Battery cycle test For the system where the positive electrode active material / negative electrode active material is lithium iron phosphate / graphite: (1) At 35°C, charge the lithium-ion battery to 3.65V at 1P constant power (constant voltage cutoff current 0.02C), let it stand for 10 minutes, then discharge it to 2.0V at 1P constant power, let it stand for 10 minutes, and repeat the charging and discharging process. Calculate the capacity retention rate of the lithium-ion battery after 1000 cycles. (2) The capacity retention rate of a lithium-ion battery after n cycles = (discharge capacity after the nth cycle / discharge capacity of the first cycle) * 100%. The average value of the capacity retention rates of three lithium-ion batteries in each group after the nth cycle is taken as the capacity retention rate of the lithium-ion battery after n cycles.

[0239] For the system where the positive electrode active material / negative electrode active material is NCM523 / graphite, NCM811 / graphite, NCM811 / (graphite + silicon-carbon composite material): the cycle test method, and the 60°C high-temperature storage for 30 days test method, DC internal resistance test method and energy efficiency test method mentioned later are basically the same as those of the lithium iron phosphate / graphite system. The only difference is that the upper and lower limit voltages of charge and discharge for the NCM523 / graphite, NCM811 / graphite, NCM811 / (graphite + silicon-carbon composite material) system are 2.75-4.2V.

[0240] For the system where the positive electrode active material / negative electrode active material is lithium iron manganese phosphate / graphite: the cycle test method, and the 60°C high temperature storage for 30 days test method, DC internal resistance test method and energy efficiency test method mentioned later are basically the same as those of the lithium iron phosphate / graphite system. The only difference is that the upper and lower limit voltages of the lithium iron phosphate / graphite system for charge and discharge are 2.5-4.3V.

[0241] (II) 60℃ high temperature storage test for 30 days For systems where the cathode active material is lithium iron phosphate: (1) Charge the battery to 3.65V at 0.5C constant current and constant voltage at room temperature (constant voltage cutoff current 0.02C), let it stand for 10 minutes, discharge it to 2.0V at 1C constant current, let it stand for 10 minutes, and record this step capacity as the original capacity C 0 ; (2) Place the 100% SOC (battery state of charge) battery in a 60°C constant temperature box and store it for 30 days; (3) After high-temperature storage, take out the battery, place it at room temperature for 8 hours, and then discharge it to 2.0V at a constant current of 1C. The capacity is recorded as C. 1Then charge to 3.65V at 0.5C constant current and constant voltage (constant voltage cut-off current 0.02C), let stand for 10 minutes, discharge to 2.0V at 1C constant current, let stand for 10 minutes, charge and discharge in this way 3 times, and record the maximum discharge capacity as C 2 ; (4) Capacity retention rate = C 1 / C 0 × 100%, capacity recovery rate = C 2 / C 0 × 100%, and the average value of the capacity retention rate / capacity recovery rate of the three lithium-ion batteries in each group is taken as the capacity retention rate / capacity recovery rate of the lithium-ion batteries in that group.

[0242] (III) Volume expansion rate test (1) Test the volume V of the battery using the Archimedean displacement method 0 .

[0243] (2) Perform high temperature storage / cycling tests on the battery.

[0244] (3) After high-temperature storage / cycling, remove the battery and test its volume V using the Archimedes displacement method. 1 .

[0245] (4) Volume expansion rate = (V 1 / V 0 -1)×100%.

[0246] (IV) DCR (DC internal resistance) test For systems where the cathode active material is lithium iron phosphate: (1) Discharge the battery at room temperature at a constant current of 0.5C to 2.0V, let it stand for 10 minutes, charge it at a constant current and voltage of 0.5C to 3.65V (constant voltage cutoff current 0.05C), let it stand for 10 minutes, and discharge it at a constant current of 0.5C to 2.0V. Record the capacity at this step as capacity C. 0 ; (2) Charge the battery at room temperature at a constant current and voltage of 0.5C to 3.65V (constant voltage cut-off current 0.05C), let it stand for 10 minutes, and discharge it at a constant current of 0.5C until 48.9% of the voltage is released. 0 Cut off after capacity; (3) After standing for 10 minutes, record the voltage as V 0 ; (4) Discharge the battery at 4C for 10 seconds and record the voltage V 1 , record the average current of the discharge process as I; (5) DCR = (V 1 -V 0 ) / I, and the average value of the DCR of each group of 3 lithium-ion batteries is taken as the DCR of the group of lithium-ion batteries.

[0247] (V) Energy efficiency test For systems where the cathode active material is lithium iron phosphate: (1) Place the battery in a 30°C constant temperature box for 8 hours; (2) Charge the battery to 3.65V at 0.5P constant power in a 30℃ constant temperature box, let it stand for 10 minutes, then charge it to 2.0V at 0.5P constant power, let it stand for 10 minutes, and repeat this process three times. The energy of the third constant power charge is recorded as E 0 , the third constant power discharge energy is recorded as E 1 ; (3) Energy efficiency = E 1 / E 0 , the average value of the energy efficiency of each group of 3 lithium-ion batteries is taken as the energy efficiency of the group of lithium-ion batteries.

[0248] (VI) Dark lines on the negative electrode interface The negative electrode interface observation method is as follows: (1) The battery cell is charged to 3.65V at 0.5C constant current and constant voltage (constant voltage cut-off current 0.05C); (2) When the ambient humidity is less than 2%, the negative electrode sheet is disassembled, peeled off and unfolded, and photographed from a 90° top angle for observation.

[0249] The negative electrode interface photos of Example 4, Example 5 and Comparative Example 1 are shown as follows: Figure 1-Figure 3 As shown. It can be seen that the negative electrode sheet of Example 5 has no dark lines, the negative electrode sheet of Example 4 has slight dark lines in the middle, and the negative electrode sheet of Comparative Example 1 has obvious dark lines in the middle. It should be noted that the 100SOC% initial interface is bright yellow, and the color will gradually fade after contact with air. The overall color of Example 5 is darker than that of Example 4 due to the shooting time and air humidity, and does not mean that there are dark lines in Example 5.

[0250] Table 1: Battery performance test results 35℃-1P / 1P1000cls cycle capacity retention rate Capacity retention rate after 30-day storage at 60℃ Capacity recovery rate after 30-day storage at 60°C DCR (mΩ) Energy efficiency Volume expansion rate after 30-day storage at 60℃ Dark lines on negative electrode interface Example 1 97.07% 95.33% 95.49% 44.16 94.91% 7.86% slight Example 2 97.64% 95.45% 95.60% 45.68 94.48% 6.05% slight Example 3 98.20% 95.59% 95.77% 48.85 94.33% 4.50% slight Example 4 98.47% 95.77% 95.90% 50.02 94.18% 3.79% slight Example 5 98.65% 95.86% 96.00% 51.19 94.12% 2.44% none Example 6 98.43% 95.03% 95.05% 55.23 94.00% 1.91% none Example 7 96.63% 94.28% 94.77% 57.20 93.87% 1.49% none Example 8 90.21% 90.33% 90.79% 59.07 94.02% 2.79% none Example 9 91.27% 95.71% 95.35% 39.70 95.20% 4.42% none Example 10 95.46% 93.23% 93.64% 42.32 94.30% 3.76% none Embodiment 11 83.79% 94.06% 95.17% 50.77 93.07% 6.06% none Example 12 97.81% 95.32% 95.64% 54.93 93.40% 1.22% none Example 13 98.23% 95.46% 95.23% 55.69 93.24% 1.33% none Embodiment 14 98.76% 95.87% 95.51% 57.05 93.08% 1.79% none Embodiment 15 98.02% 95.53% 95.74% 53.42 93.64% 1.95% none Example 16 98.32% 95.69% 95.80% 52.44 93.95% 2.21% none Embodiment 17 96.32% 94.48% 94.69% 54.32 94.42% 0.97% none Embodiment 18 97.53% 95.07% 95.43% 54.13 94.63% 1.20% none Embodiment 19 99.87% 96.11% 96.36% 54.05 94.76% 4.25% slight Embodiment 20 100.08% 96.75% 97.04% 53.86 94.91% 5.42% slight Embodiment 21 98.60% 95.55% 95.81% 47.06 94.47% 3.04% none Embodiment 22 98.59% 95.58% 95.84% 48.07 94.40% 2.80% none Embodiment 23 99.74% 96.21% 96.47% 47.00 94.46% 2.17% none Embodiment 24 96.57% 95.14% 95.33% 50.49 93.88% 3.57% none Embodiment 25 98.79% 95.80% 96.00% 45.02 94.50% 1.59% none Embodiment 26 99.05% 96.05% 96.25% 50.84 94.15% 2.36% none Embodiment 27 96.50% 94.10% 95.30% 47.12 94.43% 2.24% none Embodiment 28 98.12% 95.43% 95.69% 53.20 94.00% 2.66% none Embodiment 29 95.96% 93.04% 93.37% 45.50 94.49% 6.11% slight Embodiment 30 96.34% 94.17% 94.60% 48.80 94.31% 4.77% slight Embodiment 31 97.06% 95.28% 95.39% 50.09 94.25% 3.58% slight Embodiment 32 95.79% 93.02% 93.28% 47.80 94.22% 7.78% slight Embodiment 33 96.07% 94.11% 94.34% 50.53 94.17% 5.95% slight Embodiment 34 96.91% 95.19% 95.25% 55.78 93.85% 5.02% slight Embodiment 35 97.00% 95.25% 95.68% 58.84 92.19% 3.29% none Comparative Example 1 95.22% 92.26% 92.56% 43.10 95.27% 17.85% serious Comparative Example 2 88.58% 91.78% 92.05% 60.97 93.92% 0.57% none Comparative Example 3 91.74% 90.22% 90.48% 48.46 94.89% 3.33% none Comparative Example 4 87.88% 88.56% 89.07% 55.24 94.90% 21.77% serious Comparative Example 5 87.05% 92.76% 93.35% 35.22 94.18% 24.36% serious Comparative Example 6 91.77% 91.59% 92.03% 47.98 93.59% 20.55% serious Comparative Example 7 79.85% 90.57% 91.98% 42.55 93.44% 29.69% serious Comparative Example 8 87.58% 90.77% 91.15% 70.01 91.45% 2.11% none

[0251] From the experimental results of implementation 1-7 in Table 1, it can be seen that when the content of unsaturated silane compounds in the electrolyte is 0.1wt%-2.0wt%, the unsaturated silane compounds have the effects of inhibiting the high-temperature storage gas production of lithium-supplemented battery cells, improving the battery cell cycle performance and high-temperature storage performance, and improving the dark lines on the negative electrode interface. The higher the content of unsaturated silane compounds in the electrolyte, the better the effect of improving the high-temperature storage gas production of the battery cell. The improvement effect of the high-temperature storage performance and cycle performance of the battery cell increases first and then decreases with the addition amount of unsaturated silane compounds.

[0252] It is worth noting that the long-term cycling process of the battery cell essentially includes long-term storage. Therefore, from the experimental results of reduced gas production during high-temperature long-term storage in Table 1, it can be expected that the addition of unsaturated silane compounds to the electrolyte in the present invention can achieve the effect of reducing cyclic gas production.

[0253] It can be seen from the experimental results of Example 5 and Examples 12-16 in Table 1 that in different lithium supplement agent formulation systems, adding unsaturated silane compounds to the electrolyte has the effect of inhibiting the gas production of lithium supplement system battery cells during high-temperature storage, improving the battery cell cycle performance and high-temperature storage performance, and improving the dark lines on the negative electrode interface.

[0254] From the experimental results of Example 5 and Examples 17-20 in Table 1, it can be seen that when the ratio of P / Q is ≤2.5, the dark lines on the negative electrode interface disappear, P is the ratio of the mass of the lithium supplement agent to the total mass of the lithium supplement agent and the positive electrode active material, and Q is the mass fraction of the unsaturated silane compound in the electrolyte.

[0255] It can be seen from the experimental results of Example 5 and Examples 21-28 in Table 1 that adding unsaturated silane compounds to different electrolyte formulations has the effect of inhibiting gas production during high-temperature storage of lithium-supplemented system batteries, improving the cycle performance and high-temperature storage performance of the batteries, and improving dark lines on the negative electrode interface.

[0256] It can be seen from the experimental results of Example 5 and Examples 29-35 in Table 1 that unsaturated silane compounds such as tetravinylsilane, vinyltrimethylsilane, divinyldimethylsilane, trivinylmethylsilane, allyltriethylsilane, diallyldiethylsilane, triallylethylsilane, and tetraallylsilane can improve the cycle capacity retention rate, improve the high-temperature storage capacity retention rate and recovery rate, reduce high-temperature storage gas production, and reduce dark lines on the negative electrode interface for lithium supplements. The present invention also found that: (1) the carbon chain length of the unsaturated hydrocarbon group attached to the Si central atom will affect the viscosity of the electrolyte and the film formation impedance. Therefore, under the premise of the same number of unsaturated hydrocarbon groups, the shorter the unsaturated hydrocarbon group chain length on the Si atom, the better the effect of the unsaturated silane compound. For example, the effect of tetravinylsilane is better than that of tetrapropylenesilane. (2) When the carbon chain length of the unsaturated hydrocarbon group attached to the Si central atom is the same, for example, they are all two C olefin groups, then the number of unsaturated hydrocarbon groups is positively correlated with the effect. For example, the effect of tetravinylsilane is greater than that of trivinylsilane, greater than that of divinylsilane, and greater than that of monovinylsilane.

[0257] By comparing the experimental results of Example 5 and Comparative Example 1 in Table 1, it can be seen that the addition of unsaturated silane compounds has the effect of effectively inhibiting the gas production of lithium-supplemented system batteries during high-temperature storage, improving the battery cycle performance and high-temperature storage performance, and improving the dark lines on the negative electrode interface.

[0258] By comparing the experimental results of Example 5, Comparative Example 2 and Comparative Example 3 in Table 1, it can be seen that the non-lithium-supplemented lithium iron phosphate system itself produces less gas. Therefore, although the addition of unsaturated silane compounds still has the effect of optimizing gas production in the non-lithium-supplemented lithium iron phosphate system, it will lead to higher impedance. Therefore, unsaturated silane compounds are preferably used as electrolyte additives in lithium-supplemented systems.

[0259] By comparing the experimental results of Examples 8-11 and Comparative Examples 4-7 in Table 1, it can be seen that the unsaturated silane compounds can improve the cycle capacity retention rate, improve the high-temperature storage capacity retention rate and recovery rate, reduce high-temperature storage gas production, and reduce dark lines on the negative electrode interface in different systems of positive electrode active materials.

[0260] By comparing the experimental results of Example 5 and Comparative Example 8 in Table 1, it can be seen that further adding cyclic lithium borate compounds to the electrolyte containing unsaturated silane compounds will lead to an increase in battery cell impedance and deterioration in kinetics, thereby deteriorating the battery cell cycle life and high-temperature storage performance.

[0261] Test Example 2 The following tests were performed on the batteries of Example 36 and Comparative Example 9, and the results are shown in Table 2.

[0262] 1. Battery cycle test The only difference from Test Example 1 is that all charge and discharge currents are adjusted to 0.25P. The number of cycles is 200.

[0263] (II) 60℃ high temperature storage test for 30 days The only difference from Test Example 1 is that all parts involving charge and discharge current are adjusted to 0.25P.

[0264] (III) Volume expansion rate test The test method is the same as that of Test Example 1.

[0265] (IV) DCR test The only difference from Test Example 1 is that all charge and discharge currents in step (1) and step (2) are adjusted to 0.25C.

[0266] (V) Energy efficiency test The only difference from Test Example 1 is that all parts involving charge and discharge current are adjusted to 0.25P.

[0267] Table 2: Battery performance test results 35℃-0.25P / 0.25P200cls cycle capacity retention rate Capacity retention rate after 30-day storage at 60℃ Capacity recovery rate after 30-day storage at 60°C DCR (mΩ) Energy efficiency Volume expansion rate after 30-day storage at 60℃ Dark lines on negative electrode interface Embodiment 36 94.85% 95.16% 95.53% 58.86 97.02% 1.73% none Comparative Example 9 94.29% 94.72% 95.04% 55.06 97.09% 4.27% slight

[0268] It can be seen from Table 2 that for battery systems with low lithium salt content and low rate, the addition of unsaturated silane compounds can effectively inhibit the gas production of lithium-supplemented system cells during high-temperature storage, improve the cycle performance and high-temperature storage performance of the cells, and improve the dark lines on the negative electrode interface.

Claims

1. Application of unsaturated silane compounds in lithium ion batteries containing Li5FeO4, wherein the unsaturated silane compounds are compounds of formula I: ； In Formula I, R1, R2, R3, and R4 are each independently selected from C1-C4 alkyl, C2-C4 alkenyl, and C2-C4 alkynyl, and R1, R2, R3, and R4 are not C1-C4 alkyl at the same time; The lithium-ion battery comprises a positive electrode plate and an electrolyte, wherein the positive electrode plate comprises a positive electrode material layer, wherein the positive electrode material layer comprises a positive electrode active material and Li5FeO4, wherein the electrolyte comprises the unsaturated silane compound, wherein the ratio of the mass of Li5FeO4 to the total mass of Li5FeO4 and the positive electrode active material is P, and the mass fraction of the unsaturated silane compound in the electrolyte is Q, wherein P / Q≤30.

2. The use according to claim 1, characterized in that R1, R2, R3, R4 are each independently selected from C1-C4 alkyl and C2-C4 alkenyl; Preferably, R1, R2, R3, and R4 are each independently selected from C1-C3 alkyl and C2-C3 alkenyl; Preferably, R1, R2, R3, and R4 are each independently selected from methyl, ethyl, vinyl, and allyl; Preferably, the unsaturated silane compound is selected from tetravinylsilane, vinyltrimethylsilane, divinyldimethylsilane, trivinylmethylsilane, allyltriethylsilane, diallyldiethylsilane, triallylethylsilane and tetraallylsilane.

3. The use according to claim 1, characterized in that The application has one or more of the following characteristics: The particle size D50 of Li5FeO4 is 5-10 μm; The specific surface area of ​​Li5FeO4 is 0.3-5m 2 / g; The positive electrode material layer is disposed on one surface or both surfaces of the positive electrode current collector; The mass fraction of the unsaturated silane compound in the electrolyte is 0.001wt%-2wt%, preferably 0.01wt%-2wt%, more preferably 0.05wt%-2wt%, more preferably 0.1wt%-2wt%, for example 0.5wt%-1.5wt%, 0.8wt%-1wt%; The ratio of the mass of Li5FeO4 to the total mass of Li5FeO4 and the positive electrode active material is 0.1wt%-5wt%, preferably 0.5wt%-4wt%, more preferably 1wt%-3.5wt%, for example 1.5wt%-2.5wt%; P / Q≤25; more preferably, P / Q≤10; more preferably, P / Q≤5; more preferably, P / Q≤2.5; The positive electrode active material is selected from one or more of lithium iron phosphate, lithium iron manganese phosphate, lithium manganate, nickel-cobalt-manganese ternary positive electrode material, nickel-cobalt-aluminum ternary positive electrode material and nickel-cobalt-manganese-aluminum quaternary positive electrode material; The electrolyte does not contain cyclic lithium borate compounds, and the cyclic lithium borate compounds include lithium difluorooxalatoborate, lithium difluoromalonateborate, lithium bisoxalatoborate and lithium difluorooxalatoborate.

4. Application of unsaturated silane compounds in improving gas production, cycle performance, storage performance and / or dark lines on the negative electrode interface of lithium ion batteries containing Li5FeO4, wherein the unsaturated silane compound is a compound of formula I: ； In Formula I, R1, R2, R3, and R4 are each independently selected from C1-C4 alkyl, C2-C4 alkenyl, and C2-C4 alkynyl, and R1, R2, R3, and R4 are not C1-C4 alkyl at the same time; The lithium-ion battery comprises a positive electrode plate and an electrolyte, wherein the positive electrode plate comprises a positive electrode material layer, wherein the positive electrode material layer comprises a positive electrode active material and Li5FeO4, wherein the electrolyte comprises the unsaturated silane compound, wherein the ratio of the mass of Li5FeO4 to the total mass of Li5FeO4 and the positive electrode active material is P, and the mass fraction of the unsaturated silane compound in the electrolyte is Q, wherein P / Q≤30.

5. The use according to claim 4, characterized in that R1, R2, R3, R4 are each independently selected from C1-C4 alkyl and C2-C4 alkenyl; Preferably, R1, R2, R3, and R4 are each independently selected from C1-C3 alkyl and C2-C3 alkenyl; Preferably, R1, R2, R3, and R4 are each independently selected from methyl, ethyl, vinyl, and allyl; Preferably, the unsaturated silane compound is selected from tetravinylsilane, vinyltrimethylsilane, divinyldimethylsilane, trivinylmethylsilane, allyltriethylsilane, diallyldiethylsilane, triallylethylsilane and tetraallylsilane.

6. The use according to claim 4, characterized in that The application has one or more of the following characteristics: The particle size D50 of Li5FeO4 is 5-10 μm; The specific surface area of ​​Li5FeO4 is 0.3-5m 2 / g; The positive electrode material layer is disposed on one surface or both surfaces of the positive electrode current collector; The mass fraction of the unsaturated silane compound in the electrolyte is 0.001wt%-2wt%, preferably 0.01wt%-2wt%, more preferably 0.05wt%-2wt%, more preferably 0.1wt%-2wt%, for example 0.5wt%-1.5wt%, 0.8wt%-1wt%; The ratio of the mass of Li5FeO4 to the total mass of Li5FeO4 and the positive electrode active material is 0.1wt%-5wt%, preferably 0.5wt%-4wt%, more preferably 1wt%-3.5wt%, for example 1.5wt%-2.5wt%; P / Q≤25; more preferably, P / Q≤10; more preferably, P / Q≤5; more preferably, P / Q≤2.5; The positive electrode active material is selected from one or more of lithium iron phosphate, lithium iron manganese phosphate, lithium manganate, nickel-cobalt-manganese ternary positive electrode material, nickel-cobalt-aluminum ternary positive electrode material and nickel-cobalt-manganese-aluminum quaternary positive electrode material; The electrolyte does not contain cyclic lithium borate compounds, and the cyclic lithium borate compounds include lithium difluorooxalatoborate, lithium difluoromalonateborate, lithium bisoxalatoborate and lithium difluorooxalatoborate.

7. A lithium ion battery, characterized in that: The lithium-ion battery comprises a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator, the positive electrode sheet comprises a positive electrode current collector and a positive electrode material layer, the positive electrode material layer comprises a positive electrode active material and a lithium supplement, the lithium supplement comprises Li5FeO4, and the electrolyte comprises a lithium salt, a solvent and an unsaturated silane compound; The unsaturated silane compound is a compound of formula I: ； In Formula I, R1, R2, R3, and R4 are each independently selected from C1-C4 alkyl, C2-C4 alkenyl, and C2-C4 alkynyl, and R1, R2, R3, and R4 are not C1-C4 alkyl at the same time; The ratio of the mass of Li5FeO4 to the total mass of Li5FeO4 and the positive electrode active material is P, the mass fraction of the unsaturated silane compound in the electrolyte is Q, and P / Q≤30.

8. The lithium ion battery according to claim 7, characterized in that R1, R2, R3, R4 are each independently selected from C1-C4 alkyl and C2-C4 alkenyl; Preferably, R1, R2, R3, and R4 are each independently selected from C1-C3 alkyl and C2-C3 alkenyl; Preferably, R1, R2, R3, and R4 are each independently selected from methyl, ethyl, vinyl, and allyl; Preferably, the unsaturated silane compound is selected from tetravinylsilane, vinyltrimethylsilane, divinyldimethylsilane, trivinylmethylsilane, allyltriethylsilane, diallyldiethylsilane, triallylethylsilane and tetraallylsilane.

9. The lithium ion battery according to claim 7, characterized in that The mass fraction of the unsaturated silane compound in the electrolyte is 0.001wt%-2wt%, preferably 0.01wt%-2wt%, more preferably 0.05wt%-2wt%, more preferably 0.1wt%-2wt%, for example 0.5wt%-1.5wt%, 0.8wt%-1wt%.

10. The lithium ion battery according to claim 7, characterized in that The ratio of the mass of Li5FeO4 to the total mass of Li5FeO4 and the positive electrode active material is 0.1wt%-5wt%, preferably 0.5wt%-4wt%, more preferably 1wt%-3.5wt%, for example 1.5wt%-2.5wt%.

11. The lithium ion battery according to claim 7, characterized in that: P / Q≤25; more preferably, P / Q≤10; more preferably, P / Q≤5; more preferably, P / Q≤2.

5.

12. The lithium ion battery according to claim 7, characterized in that The positive electrode active material is selected from one or more of lithium iron phosphate, lithium manganese iron phosphate, lithium manganate, nickel-cobalt-manganese ternary positive electrode material, nickel-cobalt-aluminum ternary positive electrode material and nickel-cobalt-manganese-aluminum quaternary positive electrode material.

13. The lithium ion battery according to claim 7, characterized in that The lithium-ion battery has one or more of the following features: The particle size D50 of Li5FeO4 is 5-10 μm; The specific surface area of ​​Li5FeO4 is 0.3-5m 2 / g; The lithium salt is selected from one or more of LiFSI, LiPF6, LiTFSI and LiBF4; The mass fraction of the lithium salt in the electrolyte is 6wt%-20wt%, preferably 8wt%-15wt%; The solvent is selected from one or more of ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, propylene carbonate, diethyl carbonate, ethyl acetate and ethyl propionate; The electrolyte further comprises an additive, wherein the additive comprises one or more of an alkane film-forming additive, a silicon-based phosphate film-forming additive, a silicon-based phosphite film-forming additive, a silicon-based borate film-forming additive, a sulfur-based additive and a lithium salt additive, wherein the alkane film-forming additive is preferably selected from one or more of vinylene carbonate, fluoroethylene carbonate and vinyl ethylene carbonate, wherein the silicon-based phosphate additive is preferably selected from one or more of tris(trimethylsilane)phosphate, tris(vinyldimethylsilane)phosphate and diethyltrimethylsilylphosphate, wherein the silicon-based phosphite additive is preferably selected from one or more of tris(trimethylsilane)phosphite, tris(vinyldimethylsilane)phosphite and diethyltrimethylsilylphosphite, wherein the The silicon-based borate film-forming additive is preferably selected from one or more of tri(trimethylsilane)borate, tri(vinyldimethylsilane)borate and diethyltrimethylsilylborate, the sulfur-based additive is preferably selected from one or more of vinyl sulfate, vinyl sulfite, propenyl-1,3-sultone, methylene disulfonate, 1,3-propane sultone and 1,3-butane sultone, the lithium salt additive is preferably selected from one or more of lithium difluorophosphate, lithium difluorooxalatoborate, lithium difluorobisoxalate phosphate and lithium tetrafluorooxalate phosphate, the lithium salt additive is more preferably selected from one or more of lithium difluorophosphate, lithium difluorobisoxalate phosphate and lithium tetrafluorooxalate phosphate, and the mass fraction of the additive in the electrolyte is 0.1wt%-5wt%; The positive electrode material layer is disposed on one surface or both surfaces of the positive electrode current collector; The negative electrode sheet comprises a negative electrode current collector and a negative electrode material layer, wherein the negative electrode material layer comprises a negative electrode active material, wherein the negative electrode active material is selected from one or more of graphite and silicon-carbon composite materials, and the negative electrode material layer is arranged on one surface or both surfaces of the negative electrode current collector; The lithium supplement agent further comprises one or both of Li2NiO2 and Li2C2O4; the lithium supplement agent preferably further comprises Li2NiO2, and the mass ratio of Li5FeO4 to Li2NiO2 is preferably 1:(0.2-5), more preferably 1:(0.25-4); preferably, the particle size D50 of Li2NiO2 is 5-15 μm; preferably, the specific surface area of ​​Li2NiO2 is 0.1-1 m 2 / g; The ratio of the mass of the lithium supplement agent to the total mass of the lithium supplement agent and the positive electrode active material is 0.1 wt % to 5 wt %.

14. The lithium ion battery according to claim 7, characterized in that The electrolyte does not contain cyclic lithium borate compounds. Preferably, the cyclic lithium borate compounds include lithium difluorooxalatoborate, lithium difluoromalonateborate, lithium bisoxalatoborate and lithium difluorooxalatoborate.

15. An electrical device, characterized in that: The electrical device comprises the lithium-ion battery according to any one of claims 7 to 14.

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