WO2024074151A1

WO2024074151A1 - High-voltage battery

Info

Publication number: WO2024074151A1
Application number: PCT/CN2023/123455
Authority: WO
Inventors: 曾长安
Original assignee: 珠海冠宇电池股份有限公司
Priority date: 2022-10-08
Filing date: 2023-10-08
Publication date: 2024-04-11
Also published as: CN117894993A

Abstract

A high-voltage battery, comprising a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte solution, wherein the positive electrode sheet comprises a positive current collector, a protective layer and a positive active material layer; the protective layer is disposed on at least one side surface of the positive current collector; the electrolyte solution comprises an organic solvent and a lithium salt, and the lithium salt comprises lithium bis(fluorosulfonyl)imide and/or lithium bis(trifluoromethylsulfonyl)imide. By coating the positive current collector with the protective layer having a certain thickness, the corrosion of lithium bis(fluorosulfonyl)imide and/or lithium bis(trifluoromethylsulfonyl)imide to the positive current collector can be avoided, such that the problem of a high-voltage battery having poor normal-temperature cycling performance, high-temperature cycling performance, high-temperature storage performance and interval cycling performance at 45ºC is solved.

Description

A high voltage battery

Technical Field

The present disclosure belongs to the field of battery technology, and specifically relates to a high-voltage battery, and in particular to a high-voltage battery with good high-temperature performance.

Background technique

Since the commercialization of lithium-ion batteries, they have been widely used in digital, energy storage, power, military aerospace and communication equipment due to their light weight, high specific energy, no memory effect and good cycle performance. With the widespread application of lithium-ion batteries, consumers have put forward higher requirements for the energy density, cycle life, high temperature performance, safety and other performance of lithium-ion batteries. In order to improve the energy density, the charging voltage of the positive electrode can be increased. However, with the increase of the positive electrode voltage, the oxidation of the transition metal on the surface of the positive electrode becomes higher, and the electrolyte is prone to oxidation and decomposition reaction on the surface of the positive electrode. At the same time, the electrolyte will produce hydrofluoric acid (HF), which will corrode the positive electrode, causing the dissolution of the transition metal ions of the positive electrode. The dissolved transition metal ions migrate to the negative electrode, which will destroy the SEI film of the negative electrode, resulting in the deterioration of the battery cycle and 45°C interval cycle performance or even diving.

Summary of the invention

In order to improve the deficiencies of the prior art, the present disclosure provides a high-voltage battery. The present disclosure solves the problem of poor room temperature cycle performance, high temperature cycle performance, high temperature storage performance and 45°C interval cycle performance of high-voltage (4.45V or above) batteries due to the presence of hydrofluoric acid (HF) in the electrolyte system by using a specially treated positive electrode current collector.

The present disclosure is achieved through the following technical solutions:

A high voltage battery, comprising a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte; the positive electrode sheet comprises a positive electrode current collector, a protective layer and a positive electrode active material layer; the protective layer is arranged on at least one side of the positive electrode current collector, and the positive electrode active material layer is arranged on the surface of the protective layer; the electrolyte comprises an organic solvent and a lithium salt, and the high voltage battery meets the following requirements:

1≤a≤5;

0.05≤b≤4;

Wherein, a is the thickness of the protective layer, in μm; b is the concentration of the lithium salt in the electrolyte, in mol/L (abbreviated as M).

According to an embodiment of the present disclosure, when the lithium salt includes two or more substances, b is the sum of the concentrations of all lithium salts in the electrolyte.

According to the embodiments of the present disclosure, a is 1, 2, 3, 4, 5, or a range consisting of two or more of the above values. Arbitrary point value. When a<1, the protective layer is too thin to completely prevent the electrolyte from corroding the positive electrode current collector (such as aluminum foil), and the improvement effect on the high temperature cycle performance and 45°C interval cycle performance of the battery is not obvious, but it will deteriorate the performance of the battery; when a>5, the protective layer is thicker, which will affect the energy density of the battery.

According to an embodiment of the present disclosure, 0.5≤b≤3; for example, b is 0.5, 0.8, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.8, 2, 2.5, 2.8, 3 or any point value in the range consisting of any two of the above point values. Preferably, 1≤b≤2.

According to an embodiment of the present disclosure, the protective layer includes a protective material, and the protective material is selected from one or more of the following substances: carbon, Al ₂ O ₃ , TiO ₂ , MgO, FeO, Fe ₂ O ₃ , Fe ₃ O ₄ , Cr ₂ O ₃ , CoO, Ce ₂ O ₃ , In ₂ O ₃ , Ti ₂ O ₃ , V ₂ O ₅ , WO ₃ , ZnO, Nb ₂ O ₅ , NiO, SnO ₂ and AlF ₃ , wherein some substances may contain multiple isomers, such as the isomers of Al ₂ O ₃ include α-Al ₂ O ₃ , β-Al ₂ O ₃ and γ-Al ₂ O ₃ , wherein the carbon may be amorphous carbon, carbon black, hard carbon, soft carbon, carbon nanotubes, conductive graphite, and the like.

According to an embodiment of the present disclosure, the protective layer may further include at least one of a first conductive agent and a first adhesive. The conductive agent and the adhesive are defined as follows.

According to an embodiment of the present disclosure, the mass percentage of each component in the protective layer is: 90wt% to 100wt% of the protective material (for example, 90wt%, 91wt%, 92wt%, 93wt%, 94wt%, 95wt%, 96wt%, 97wt%, 98wt%, 99wt% or 100wt%), 0wt% to 5wt% of the first conductive agent (for example, 5wt%, 4.5wt%, 4wt%, 3.5wt%, 3wt%, 2.5wt%, 2wt%, 1.5wt%, 1wt%, 0.5wt% or 0wt%), and 0wt% to 5wt% of the first binder (for example, 5wt%, 4.5wt%, 4wt%, 3.5wt%, 3wt%, 2.5wt%, 2wt%, 1.5wt%, 1wt%, 0.5wt% or 0wt%).

According to an embodiment of the present disclosure, the organic solvent is selected from one or more of carbonates and/or carboxylates.

Illustratively, the carbonate is selected from one or more of the following fluorinated or unsubstituted solvents: ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate.

Illustratively, the carboxylic acid ester is selected from one or more of the following fluorinated or unsubstituted solvents: propyl acetate, n-butyl acetate, isobutyl acetate, n-amyl acetate, isoamyl acetate, ethyl propionate, n-propyl propionate, methyl butyrate and ethyl butyrate.

According to an embodiment of the present disclosure, the electrolyte further includes one or more of the following additives: vinylene carbonate, vinyl carbonate, fluoroethylene carbonate, vinyl sulfite, lithium difluorophosphate, methylene disulfonate, vinyl sulfate, succinonitrile, glutaronitrile, adiponitrile, pimelonitrile, suberonitrile, sunflower dinitrile, 1,3,6-hexanetrinitrile, 3-methoxypropionitrile, glycerol trinitrile, 1,2-bis(2-cyanoethoxy)ethane, 1,3-propane sultone and propenyl-1,3-sultone.

According to an embodiment of the present disclosure, the lithium salt includes lithium bis(fluorosulfonyl)imide and/or lithium bis(trifluoromethylsulfonyl)imide.

According to an embodiment of the present disclosure, the lithium salt further comprises lithium hexafluorophosphate, lithium difluorophosphate and tetrafluoroborate. One or more of lithium oxides.

According to an embodiment of the present disclosure, the positive electrode active material layer includes a positive electrode active material, a second conductive agent, and a second binder.

According to an embodiment of the present disclosure, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer coated on one or both sides of the negative electrode current collector, and the negative electrode active material layer includes a negative electrode active material, a third conductive agent and a third binder.

According to an embodiment of the present disclosure, the mass percentage of each component in the positive electrode active material layer is: 80wt% to 99.8wt% of the positive electrode active material (for example, 80wt%, 85wt%, 90wt%, 95wt% or 99.8wt%), 0.1wt% to 10wt% of the second conductive agent (for example, 10wt%, 7.5wt%, 5wt%, 2.5wt% or 0.1wt%), and 0.1wt% to 10wt% of the second binder (for example, 10wt%, 7.5wt%, 5wt%, 2.5wt% or 0.1wt%).

Preferably, the mass percentage of each component in the positive electrode active material layer is: 90wt% to 99.6wt% of the positive electrode active material, 0.2wt% to 5wt% of the second conductive agent, and 0.2wt% to 5wt% of the second binder.

According to an embodiment of the present disclosure, the mass percentage of each component in the negative electrode active material layer is: 80wt% to 99.8wt% of the negative electrode active material (for example, 80wt%, 85wt%, 90wt%, 95wt% or 99.8wt%), 0.1wt% to 10wt% of the third conductive agent (for example, 10wt%, 7.5wt%, 5wt%, 2.5wt% or 0.1wt%), and 0.1wt% to 10wt% of the third binder (for example, 10wt%, 7.5wt%, 5wt%, 2.5wt% or 0.1wt%).

Preferably, the mass percentage of each component in the negative electrode active material layer is: 90wt% to 99.6wt% of the negative electrode active material, 0.2wt% to 5wt% of the third conductive agent, and 0.2wt% to 5wt% of the third binder.

According to an embodiment of the present disclosure, the negative electrode active material layer may further include a thickener, and the mass percentage of each component in the negative electrode active material layer is: 80wt% to 99.8wt% of the negative electrode active material (for example, 80wt%, 85wt%, 90wt%, 95wt% or 99.8wt%), 0.05wt% to 10wt% of the third conductive agent (for example, 10wt%, 5wt%, 1wt% or 0.05wt%), 0.05wt% to 5wt% of the third binder (for example, 5wt%, 1wt% or 0.05wt%) and 0.1wt% to 5wt% of the thickener (for example, 10wt%, 5wt%, 1wt% or 0.1wt%).

Preferably, the mass percentage of each component in the negative electrode active material layer is: 91wt% to 99wt% of negative electrode active material, 0.1wt% to 4wt% of the third conductive agent, 0.1wt% to 2.5wt% of the third binder and 0.1wt% to 2.5wt% of the thickener.

According to an embodiment of the present disclosure, the first conductive agent, the second conductive agent and the third conductive agent are each independently selected from at least one of conductive carbon black, acetylene black, Ketjen black, conductive graphite, conductive carbon fiber, carbon nanotubes and metal powder.

According to an embodiment of the present disclosure, the first binder, the second binder and the third binder are each independently selected from at least one of sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, styrene-butadiene rubber, polytetrafluoroethylene, polyvinylidene fluoride and polyethylene oxide.

According to an embodiment of the present disclosure, the positive electrode active material in the positive electrode active material layer is selected from one or more of layered lithium composite oxides, lithium manganate and ternary materials. The formula is Li _(1+x) Ni _y Co _z M _(1-yz) O ₂ , wherein -0.1≤x≤1; 0≤y≤1, 0≤z≤1, and 0≤y+z≤1; wherein M is one or more of Mg, Zn, Ga, Ba, Al, Fe, Cr, Sn, V, Mn, Sc, Ti, Nb, Mo and Zr.

According to an embodiment of the present disclosure, the negative electrode active material in the negative electrode active material layer is selected from one or more of carbon-based negative electrode materials, silicon-based negative electrode materials, tin-based negative electrode materials or their corresponding alloy materials.

According to an embodiment of the present disclosure, the carbon-based negative electrode material includes at least one of artificial graphite, natural graphite, mesophase carbon microbeads, hard carbon and soft carbon.

According to an embodiment of the present disclosure, the silicon-based negative electrode material is selected from at least one of nano-silicon (Si), silicon-oxygen negative electrode material (SiOx (0<x<2)) and silicon-carbon negative electrode material.

According to an embodiment of the present disclosure, the tin-based negative electrode material is selected from one or more of metallic tin, tin oxide, tin alloy material and tin-based composite oxide.

According to an embodiment of the present disclosure, the operating cut-off voltage of the high voltage battery is 4.45V and above.

Beneficial effects of the present disclosure:

The present disclosure provides a high-voltage battery. The high-voltage battery of the present disclosure can solve the corrosion of HF generated by the decomposition of lithium hexafluorophosphate to the positive transition metal ions. At the same time, compared with lithium hexafluorophosphate, when the electrolyte includes lithium bis(fluorosulfonyl)imide and/or lithium bis(trifluoromethylsulfonyl)imide, no hydrofluoric acid is generated, so that the positive transition metal will not be corroded, and the transition metal ions will not be dissolved. In addition, the side reactions on the positive electrode surface and the gas production and interface protection layer destruction and phase change caused by the side reactions can be reduced. However, lithium bis(fluorosulfonyl)imide and lithium bis(trifluoromethylsulfonyl)imide as the main lithium salts may cause certain corrosion to the positive current collector. Coating a protective layer of a certain thickness on the positive current collector can solve the problem of corrosion to the positive current collector. Therefore, through the above-mentioned synergistic effect, the problems of poor normal temperature cycle performance, high temperature cycle performance, high temperature storage performance and 45°C interval cycle performance of the high-voltage battery are solved.

Detailed ways

The present disclosure will be further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only exemplary illustrations and explanations of the present disclosure and should not be construed as limiting the scope of protection of the present disclosure. All technologies implemented based on the above content of the present disclosure are included in the scope of protection intended by the present disclosure.

Unless otherwise specified, the experimental methods used in the following examples are all conventional methods; the reagents, materials, etc. used in the following examples, unless otherwise specified, can be obtained from commercial channels.

Comparative Example 1

(1) Preparation of positive electrode

The positive electrode active material 4.5V lithium cobalt oxide (LCO), the binder polyvinylidene fluoride (PVDF) and the conductive agent Acetylene black is mixed in a weight ratio of 98:1.5:0.5, N-methylpyrrolidone (NMP) is added, and the mixture is stirred under the action of a vacuum stirrer until the mixed system becomes a positive electrode slurry with uniform fluidity; the positive electrode slurry is evenly coated on an aluminum foil with a thickness of 9 μm; the coated aluminum foil is baked in an oven with 5 different temperature gradients, and then dried in an oven at 120°C for 8 hours, and then rolled and cut to obtain a positive electrode sheet.

(2) Negative electrode preparation

The negative electrode active material graphite (artificial graphite), the thickener sodium carboxymethyl cellulose (CMC-Na), the binder styrene butadiene rubber and the conductive agent acetylene black were mixed in a weight ratio of 97:1:1:1, and deionized water was added to obtain a negative electrode slurry under the action of a vacuum mixer; the negative electrode slurry was evenly coated on a copper foil with a thickness of 8 μm; the copper foil was dried at room temperature and then transferred to an oven at 80°C for drying for 10 hours, and then cold pressed and cut to obtain a negative electrode sheet, the compaction density of the negative electrode sheet was 1.80 g/ ^cm3 , and the surface density was 9.5 mg/ ^cm2 .

(3) Preparation of electrolyte

In a glove box filled with argon and having a qualified water and oxygen content, ethylene carbonate, propylene carbonate and n-propyl propionate are mixed evenly in a mass ratio of 15:15:70 (the solvent and the additive need to be normalized together), the solvent is frozen at a low temperature of about -10°C for 2-5h, and then a fully dried lithium salt (as shown in Table 1) is quickly added thereto, stirred evenly, and then 8wt% of fluoroethylene carbonate, 4wt% of 1,3-propane sultone, 1wt% of succinonitrile, 1wt% of adiponitrile, 3wt% of 1,3,6-hexanetrinitrile, and 0.3wt% of lithium difluorophosphate are added, and stirred again until uniform. After the moisture and free acid tests are qualified, the electrolyte of Comparative Example 1 is obtained.

(4) Preparation of diaphragm

A polyethylene diaphragm with a thickness of 8 μm (provided by Asahi Kasei Corporation) was selected.

(5) Preparation of lithium-ion batteries

The positive electrode sheet, separator and negative electrode sheet prepared above are stacked in order, ensuring that the separator is between the positive and negative electrode sheets to play an isolating role, and then a bare battery cell without liquid injection is obtained by winding; the bare battery cell is placed in an outer packaging foil, and the prepared electrolyte is injected into the dried bare battery cell. After vacuum packaging, standing, forming, shaping, sorting and other processes, the required lithium-ion battery is obtained.

(6) 25℃ normal temperature cycling experiment and post-cycling anatomy

Before the test, the thickness D ₀ of the fully charged cell was tested. The battery was placed in a (25±3)℃ environment and left to stand for 3 hours. When the cell body reached (25±3)℃, the battery was charged to 4.2V at 1C, then charged to 4.5V at 0.7C, then charged to a cut-off current of 0.05C at 4.5V constant voltage, and then discharged to 3V at 0.5C. The initial capacity Q ₀ was recorded. When the cycle reached the required number of times, the discharge capacity was used as the battery capacity Q ₂ , and the capacity retention rate (%) was calculated. The battery was fully charged again, the cell was taken out, and left to stand at room temperature for 3 hours. The fully charged thickness D ₂ was tested, and the thickness change rate (%) was calculated. The results were recorded as shown in Table 2. The calculation formula used is as follows:

Thickness change rate (%) = (D ₂ - D ₀ )/D ₀ × 100%; Capacity retention rate (%) = Q ₂ /Q ₀ × 100%.

After the cycle, the battery is fully charged and disassembled to determine whether its aluminum foil is corroded.

(7) 45℃ high temperature cycle test

Before the test, the thickness D ₀ of the fully charged cell was tested. The battery was placed in a (45±3)℃ environment and left to stand for 3 hours. When the cell body reached (45±3)℃, the battery was charged to 4.5V at a constant current of 0.7C, and charged to a cut-off current of 0.05C at a constant voltage of 4.5V, and then discharged at 0.5C, and the initial capacity Q ₀ was recorded. This cycle was repeated. When the cycle reached the required number of times, the discharge capacity was used as the capacity Q ₃ of the battery, and the capacity retention rate (%) was calculated. The battery was fully charged again, the cell was taken out, and left to stand at room temperature for 3 hours. The fully charged thickness D ₃ was tested at this time, and the thickness change rate (%) was calculated. The results were recorded as shown in Table 2. The calculation formula used is as follows:

Thickness change rate (%) = (D ₃ - D ₀ )/D ₀ × 100%; Capacity retention rate (%) = Q ₃ /Q ₀ × 100%.

(8) 45℃ interval cycle test

Before the test, the thickness D ₀ of the fully charged battery cell was tested. The battery was placed in a (45±3)℃ environment and left to stand for 3 hours. When the battery cell reached (45±3)℃, the battery was charged to 4.5V at a constant current of 0.7C, and charged to a cut-off current of 0.05C at a constant voltage of 4.5V. The battery was left to stand at 45℃ for a certain period of time to ensure that the constant current and constant voltage charging time plus the standing time was 24H. The battery was then discharged at 0.5C and the initial energy E ₀ was recorded. The cycle was repeated in this way. When the cycle reached the required number of times, the discharge energy was used as the battery energy E ₁ , and the energy retention rate (%) was calculated. The battery was then fully charged, the core was taken out, and left to stand at room temperature for 3 hours. The fully charged thickness D ₄ was tested at this time, and the thickness change rate (%) was calculated. The results were recorded as shown in Table 2. The calculation formula used is as follows:

Thickness change rate (%) = (D ₄ - _{D 0} )/D ₀ × 100%; Energy retention rate (%) = E ₁ /E ₀ × 100%.

(9) 60℃ high temperature storage test

At 25°C, the thickness D ₀ of the fully charged cell was tested. The sorted battery was charged to 4.5V at 0.7C, then charged to a cut-off current of 0.05C at 4.5V constant voltage, then discharged to 3.0V at 0.5C constant current, then charged to 4.5V at 0.7C, then charged to a cut-off current of 0.05C at 4.5V constant voltage, and then placed in a 60°C environment for 35 days. The fully charged thickness D ₅ was tested, and the thickness change rate (%) was calculated. The results are recorded as shown in Table 2. The calculation formula used is as follows:

Thickness change rate (%) = (D ₅ -D ₀ )/D ₀ × 100%.

Examples 1-11 and Comparative Examples 2-4

The preparation process of Examples 1-11 and Comparative Examples 2-4 is the same as that of Comparative Example 1, except that the aluminum foil contains a protective layer and the content and type of the lithium salt in the electrolyte are different, specifically:

A protective layer is coated on the surface of the aluminum foil. The material forming the protective layer is shown in Table 1. The thickness of the protective layer is 2 μm. The preparation of the electrolyte is the same as that of Comparative Example 1, except that the amount and type of lithium salt added are different, as shown in Table 1.

Table 1 Composition of the protective layer and the electrolyte in the electrolyte of the embodiment and the comparative example

It can be seen from Table 2 that the batteries prepared in the embodiments of the present application have achieved better electrical performance. The improvement in the capacity retention rate and thickness expansion rate during the battery cycle can prove the effect achieved by the cathode current collector of the present application using a special protective coating, a combination and a special lithium salt or a lithium salt combination electrolyte. The specific analysis is as follows:

By comparing Comparative Examples 2-4 with Comparative Example 1, it can be found that when there is no coating on the positive electrode current collector aluminum foil, when lithium bis(fluorosulfonyl)imide or lithium bis(trifluoromethylsulfonyl)imide is used as the lithium salt, there is a problem of corrosion of the aluminum foil and deterioration of the cycle performance and storage performance.

By comparing Examples 1-2, 9 and Comparative Examples 2-3, or Examples 3-4, 10 and Comparative Examples 2-3, or Examples 5-6, 11 and Comparative Examples 2-3, or Example 7 and Comparative Example 4, it can be found that when a protective layer such as carbon _, _Al2O3 or _TiO2 is coated on the positive electrode current collector aluminum foil, compared with lithium hexafluorophosphate, when lithium bis(fluorosulfonyl)imide or lithium bis(trifluoromethylsulfonyl)imide is used as the lithium salt, the room temperature cycle performance, 45°C cycle performance, 45°C interval cycle performance and 60°C storage performance of the battery are all improved.

By comparing Example 8 with Example 3, it can be found that appropriately increasing the content of lithium bis(fluorosulfonyl)imide has little effect on battery performance.

Table 2 Comparison of experimental results of batteries of embodiment and comparative example

The above describes the implementation methods of the present disclosure. However, the present disclosure is not limited to the above implementation methods. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

A high voltage battery, characterized in that the high voltage battery comprises a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte; the positive electrode sheet comprises a positive electrode current collector, a protective layer and a positive electrode active material layer; the protective layer is arranged on at least one side of the positive electrode current collector, and the positive electrode active material layer is arranged on the surface of the protective layer; the electrolyte comprises an organic solvent and a lithium salt;

The high voltage battery satisfies the following relationship:
1≤a≤5;
0.05≤b≤4;

Wherein, a is the thickness of the protective layer, in μm; b is the concentration of the lithium salt in the electrolyte, in mol/L.
The high voltage battery according to claim 1, characterized in that 0.5≤b≤3; preferably 1≤b≤2.
The high voltage battery according to claim 1 or 2, characterized in that the lithium salt comprises lithium bis(fluorosulfonyl)imide and/or lithium bis(trifluoromethylsulfonyl)imide.
The high voltage battery according to any one of claims 1 to 3, characterized in that the protective layer comprises a protective material, and the protective material is selected from one or more of the following substances: carbon, Al 2 O 3 , TiO 2 , MgO, FeO, Fe 2 O 3 , Fe 3 O 4 , Cr 2 O 3 , CoO, Ce 2 O 3 , In 2 O 3 , Ti 2 O 3 , V 2 O 5 , WO 3 , ZnO, Nb 2 O 5 , NiO, SnO 2 and AlF 3 .
The high voltage battery according to claim 4, characterized in that the Al 2 O 3 comprises at least one of α-Al 2 O 3 , β-Al 2 O 3 and γ-Al 2 O 3 ;

And/or, the carbon includes at least one of amorphous carbon, carbon black, hard carbon, soft carbon, carbon nanotubes and conductive graphite.
The high voltage battery according to any one of claims 1 to 5, characterized in that the protective layer further comprises at least one of a first conductive agent and a first binder;

Preferably, the mass percentage of each component in the protective layer is: 90wt% to 100wt% of the protective material, 0wt% to 5wt% of the first conductive agent and 0wt% to 5wt% of the first binder.
The high voltage battery according to any one of claims 1 to 6, characterized in that the lithium salt further comprises one or more of lithium hexafluorophosphate, lithium difluorophosphate and lithium tetrafluoroborate.
The high voltage battery according to any one of claims 1 to 7, characterized in that the organic solvent is selected from one or more of carbonates and/or carboxylates;

Preferably, the carbonate is selected from one or more of the following fluorinated or unsubstituted solvents: ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate;

Preferably, the carboxylic acid ester is selected from one or more of the following fluorinated or unsubstituted solvents: propyl acetate, n-butyl acetate, isobutyl acetate, n-amyl acetate, isoamyl acetate, ethyl propionate, n-propyl propionate, Esters, methyl butyrate and ethyl butyrate.
The high-voltage battery according to any one of claims 1 to 8, characterized in that the electrolyte further comprises one or more of the following additives: vinylene carbonate, vinyl carbonate, fluoroethylene carbonate, vinyl sulfite, lithium difluorophosphate, methylene methanedisulfonate, vinyl sulfate, succinonitrile, glutaronitrile, adiponitrile, pimelonitrile, suberonitrile, sunflower dinitrile, 1,3,6-hexanetrinitrile, 3-methoxypropionitrile, glycerol trinitrile, 1,2-bis(2-cyanoethoxy)ethane, 1,3-propanesultone and propenyl-1,3-sultone.
The high voltage battery according to any one of claims 1 to 9, characterized in that the positive electrode active material in the positive electrode active material layer is selected from one or more of layered lithium composite oxides, lithium manganese oxide and ternary materials;

Preferably, the chemical formula of the layered lithium composite oxide is Li (1+x) Ni y Co z M (1-yz) O 2 , wherein -0.1≤x≤1; 0≤y≤1, 0≤z≤1, and 0≤y+z≤1; wherein M is one or more of Mg, Zn, Ga, Ba, Al, Fe, Cr, Sn, V, Mn, Sc, Ti, Nb, Mo and Zr.
The high-voltage battery according to any one of claims 1 to 10, characterized in that the negative electrode sheet comprises a negative electrode current collector and a negative electrode active material layer coated on one side or both sides of the negative electrode current collector, and the negative electrode active material layer comprises a negative electrode active material.
The high-voltage battery according to claim 11 is characterized in that the negative electrode active material is selected from one or more of a carbon-based negative electrode material, a silicon-based negative electrode material, a tin-based negative electrode material or their corresponding alloy materials.
The high voltage battery according to claim 12, characterized in that the carbon-based negative electrode material comprises at least one of artificial graphite, natural graphite, mesophase carbon microbeads, hard carbon and soft carbon;

And/or, the silicon-based negative electrode material is selected from at least one of nano-silicon, silicon-oxygen negative electrode material (SiOx (0<x<2)) and silicon-carbon negative electrode material;

And/or, the tin-based negative electrode material is selected from at least one of metallic tin, tin oxide, tin alloy material and tin-based composite oxide.
The high-voltage battery according to any one of claims 1 to 13, characterized in that the thickness change rate of the high-voltage battery after 1000 cycles at 25°C is ≤11.5%, and the capacity retention rate of the high-voltage battery after 1000 cycles at 25°C is ≥72.1%;

And/or, the thickness change rate of the high-voltage battery after 500 cycles at 45°C is ≤12.5%, and the capacity retention rate of the high-voltage battery after 500 cycles at 45°C is ≥74.2%;

And/or, the thickness change rate of the high voltage battery after 100 cycles at 45°C is ≤13.0%, and the energy retention rate of the high voltage battery after 100 cycles at 45°C is ≥75.4%;

And/or, the thickness change rate of the high voltage battery after being stored at 60° C. for 35 days is ≤9.2%.
The high-voltage battery according to any one of claims 1-14, characterized in that the operating cut-off voltage of the high-voltage battery is 4.45V and above.