WO2019210559A1 - Non-aqueous electrolyte for lithium ion battery and lithium ion battery - Google Patents

Abstract

In order to overcome the problems of insufficient cycle performance and temperature storage performance in existing lithium ion batteries, the present invention provides a non-aqueous electrolyte for a lithium ion battery, comprising a solvent, lithium salts, and one or more of compounds presented by structural formula 1. In structure formula 1, R is a single bond or methylene; R₁ is represented by formula (II), (III), or (IV); R₂ and R₃ are selected from hydrogen or halogen; and m is an integer ranging from 1 to 4, and n is an integer ranging from 0 to 2. Moreover, also disclosed in the present invention is a lithium ion battery comprising the non-aqueous electrolyte. The non-aqueous electrolyte for a lithium ion battery provided by the present invention facilitates the improvement of the high-temperature storage performance and the high-temperature cycle performance of a battery.

Description

Lithium ion battery non-aqueous electrolyte and lithium ion battery Technical field

The invention belongs to the technical field of lithium ion batteries, and particularly relates to a lithium ion battery non-aqueous electrolyte and a lithium ion battery.

Background technique

Compared with lead-acid batteries, nickel-hydrogen batteries or nickel-cadmium batteries, lithium-ion batteries have made great progress in the field of portable electronic products due to their high operating voltage, high safety, long life and no memory effect. With the development of new energy vehicles, lithium-ion batteries have great application prospects in power supply systems for new energy vehicles.

The lithium ion battery electrolyte consists of a solute and an organic solvent, the solute is mainly lithium hexafluorophosphate, and the organic solvent is mainly composed of a cyclic carbonate and a linear carbonate. During the first charging of the lithium ion battery, the lithium salt and the organic solvent undergo a reductive decomposition reaction on the surface of the negative electrode, and the decomposition product forms a passivation film on the surface of the negative electrode, and the passivation film is called a solid electrolyte interface film (SEI). The formed passivation film can effectively inhibit further decomposition of the organic solvent and the lithium salt, and the formed passivation film is ion-conducting and electrons are not conductive.

During the subsequent high-temperature storage or high-temperature cycle of the lithium-ion battery, the SEI film is continuously destroyed and repaired, and the electrolyte is continuously consumed and the internal resistance of the battery is gradually increased, eventually leading to battery performance diving. Many researchers have improved the performance of SEI membranes by adding different negative film-forming additives (such as vinylene carbonate, vinyl fluorocarbonate, ethylene ethylene carbonate) to the electrolyte to improve the performance of the battery. For example, it is proposed in Japanese Patent Laid-Open Publication No. 2000-123867 to improve battery characteristics by adding vinylene carbonate to an electrolytic solution. The vinylene carbonate can preferentially decompose and decompose on the surface of the negative electrode by the solvent molecule, and can form a passivation film on the surface of the negative electrode to prevent the electrolyte from further decomposing on the surface of the electrode, thereby improving the cycle performance of the battery. However, after the addition of vinylene carbonate, the battery is prone to generate gas during high-temperature storage, causing the battery to swell. In addition, the passivation film formed by vinylene carbonate has a large impedance, especially under low temperature conditions, it is prone to low-temperature charge and lithium deposition, which affects battery safety. The fluoroethylene carbonate can also form a passivation film on the surface of the negative electrode to improve the cycle performance of the battery, and the passivation film formed has a relatively low impedance, which can improve the low-temperature discharge performance of the battery. However, fluoroethylene carbonate produces more gas at high temperature storage, which significantly reduces the high temperature storage performance of the battery.

Summary of the invention

In view of the problem that the existing lithium ion battery has insufficient cycle performance and temperature storage performance, the present invention provides a lithium ion battery nonaqueous electrolyte and a lithium ion battery.

The technical solution adopted by the present invention to solve the above technical problems is as follows:

In one aspect, the present invention provides a lithium ion battery nonaqueous electrolyte comprising a solvent, a lithium salt, and one or more selected from the group consisting of compounds of Structural Formula 1;

In Structural Formula 1, R is a single bond or a methylene group, and R ₁ is

R ₂ and R _{3 are} selected from hydrogen or halogen, and m is selected from an integer of 1 to 4, and n is selected from an integer of 0 to 2.

Alternatively, the compound represented by Structural Formula 1 is selected from the following compounds:

Optionally, the compound represented by the structural formula 1 has a mass percentage of 0.1% to 5% based on 100% of the total mass of the nonaqueous electrolyte of the lithium ion battery.

Optionally, the non-aqueous electrolyte further comprises one or more of an unsaturated cyclic carbonate, a fluorinated cyclic carbonate, a cyclic sultone, and a cyclic sulfate.

Optionally, the unsaturated cyclic carbonate includes one or more of vinylene carbonate, ethylene carbonate, and methylene carbonate;

The fluorinated cyclic carbonate includes one or more of fluoroethylene carbonate, trifluoromethyl ethylene carbonate, and difluoroethylene carbonate;

The cyclic sultone lactone includes one or more of 1,3-propane sultone, 1,4-butane sultone and acryl-1,3- sultone;

The cyclic sulfate is selected from one or more of the group consisting of vinyl sulfate and 4-methylsulfate.

Optionally, in the non-aqueous electrolyte, the content of the unsaturated cyclic carbonate is 0.01%-10%; the content of the fluorinated cyclic carbonate is 0.01%-30%; the content of the cyclic sultone It is 0.01% to 10%; the content of the cyclic sulfate is 0.01% to 10%.

Optionally, the solvent is a mixture of a cyclic carbonate and a chain carbonate;

The cyclic carbonate is selected from one or more of the group consisting of ethylene carbonate, propylene carbonate, and butylene carbonate;

The chain carbonate is selected from one or more of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and methyl propyl carbonate.

Optionally, the lithium salt is selected from one or more of LiPF ₆ , LiBF ₄ , LiBOB, LiDFOB, LiN(SO ₂ CF ₃ ) ₂ and LiN(SO ₂ F) ₂ .

In another aspect, the present invention also provides a lithium ion battery comprising a positive electrode, a negative electrode, and a lithium ion battery nonaqueous electrolyte as described above.

Optionally, the positive electrode comprises a positive active material, and the active material of the positive electrode is LiNi _x Co _y MnzL _(1-xyz) O ₂ , LiCo _x′ L _(1-x′) O ₂ , LiNi _x” L′ At least one of _y' Mn _(2-x"-y') O ₄ and Li _{z '} MPO ₄ ; wherein L is at least at least one of Al, Sr, Mg, Ti, Ca, Zr, Zn, Si or Fe One; 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, 0 ≤ z ≤ 1, 0 < x + y + z ≤ 1, 0 < x ' ≤ 1, 0.3 ≤ x" ≤ 0.6, 0.01 ≤ y' ≤ 0.2; L' is at least one of Co, Al, Sr, Mg, Ti, Ca, Zr, Zn, Si, Fe; 0.5 ≤ z' ≤ 1, and M is at least one of Fe, Mn, and Co.

According to the nonaqueous electrolyte of the lithium ion battery provided by the present invention, the cyclic carbonate compound represented by the structural formula 1 is added, and the inventors have found through a large number of experiments that the structural formula 1 provided by the present invention is compared with the existing electrolyte additive. The cyclic carbonate compound is more favorable for the formation of a passivation film on the surface of the negative electrode, and the cyclic carbonate compound can form a passivation film on the surface of the negative electrode to form a passivation film, and the two cyclic carbonates pass through a spiro bond, a single bond, and sulfuric acid. The root functional groups link to form a more efficient passivation film, thus improving the high temperature storage and cycling performance of the battery.

detailed description

In order to make the technical problems, technical solutions and beneficial effects of the present invention more clear, the present invention will be further described in detail below with reference to the embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

An embodiment of the present invention provides a lithium ion battery non-aqueous electrolyte, comprising a solvent, a lithium salt, and one or more selected from the group consisting of compounds of Structural Formula 1;

In Structural Formula 1, R is a single bond or a methylene group; R ₁ is

or

R ₂ and R _{3 are} selected from hydrogen or halogen, and m is selected from an integer of 1 to 4, and n is selected from an integer of 0 to 2.

The inventors have found through a large number of experiments that the cyclic carbonate compound represented by Structural Formula 1 provided by the present invention is more advantageous for the formation of a passivation film on the surface of the negative electrode than the conventional electrolyte additive, and the cyclic carbonate compound can be in the negative electrode. A ring-opening reaction occurs on the surface to form a passivation film. The two cyclic carbonates are linked by a spiro bond, a single bond, and a sulfate functional group to form a more effective passivation film, thereby improving the high-temperature storage and cycle performance of the battery.

In some embodiments, the compound of Structural Formula 1 is selected from the group consisting of:

With respect to the compound represented by Structural Formula 1, a person skilled in the art of chemical synthesis can easily think of the synthetic route of the corresponding compound based on the structural formula of the above compound. For example, the compound 1 can be prepared by the following synthetic route:

The compound 2 can be prepared by the following synthetic route:

The compound 3 can be prepared by the following synthetic route:

It is to be noted that the above are some of the compounds claimed in the present invention, but are not limited thereto, and should not be construed as limiting the present invention.

In some embodiments, the compound represented by the structural formula 1 has a mass percentage of 0.1% to 5%, based on 100% by mass of the total mass of the lithium ion battery non-aqueous electrolyte. Specifically, the structural formula The mass percentage of the compound shown by 1 may be 0.3%, 0.6%, 1%, 1.2%, 1.5%, 1.8%, 2.0%, 2.3%, 2.6%, 2.9%, 3.1%, 3.5%, 3.7%. , 4.0%, 4.3%, 4.5% or 4.8%.

In some embodiments, the non-aqueous electrolyte further comprises one or more of an unsaturated cyclic carbonate, a fluorocyclic carbonate, a cyclic sultone, and a cyclic sulfate.

In a more preferred embodiment, the unsaturated cyclic carbonate includes vinylene carbonate (CAS: 872-36-6), ethylene carbonate (CAS: 4427-96-7), methylene carbonate One or more of vinyl esters (CAS: 124222-05-5). Preferably, in the nonaqueous electrolytic solution, the content of the unsaturated cyclic carbonate is from 0.01% to 10%, more preferably from 0.1% to 5%.

The fluorinated cyclic carbonate includes fluoroethylene carbonate (CAS: 114435-02-8), trifluoromethyl ethylene carbonate (CAS: 167951-80-6), and bisfluoroethylene carbonate (CAS: One or more of 311810-76-1). Preferably, in the nonaqueous electrolytic solution, the content of the fluorinated cyclic carbonate is from 0.01% to 30%, more preferably from 0.1% to 3%.

The cyclic sultone lactone includes 1,3-propane sultone (CAS: 1120-71-4), 1,4-butane sultone (CAS: 1633-83-6), and propylene-1 One or more of 3-sulfonate (CAS: 21806-61-1). Preferably, in the nonaqueous electrolytic solution, the content of the cyclic sultone is from 0.01% to 10%, more preferably from 0.1% to 5%.

The cyclic sulfate is selected from one or more of the group consisting of vinyl sulfate (CAS: 1072-53-3) and 4-methylsulfate (CAS: 5689-83-8). Preferably, in the nonaqueous electrolytic solution, the content of the cyclic sulfate is 0.01% to 10%, more preferably 0.1% to 5%.

As in the prior art, the lithium ion battery non-aqueous electrolyte solution contains a solvent and a lithium salt, and the solvent type and content are not particularly limited in the embodiment of the present invention.

In some preferred embodiments, the solvent of the lithium ion battery nonaqueous electrolyte is a mixture of a cyclic carbonate and a chain carbonate.

Preferably, the cyclic carbonate is selected from one or more of the group consisting of ethylene carbonate, propylene carbonate and butylene carbonate.

The chain carbonate is selected from one or more of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and methyl propyl carbonate.

The lithium salt is not particularly limited in the present invention, and various existing ones can be used.

In some preferred embodiments, the lithium salt is selected from one or more of LiPF ₆ , LiBF ₄ , LiBOB, LiDFOB, LiN(SO ₂ CF ₃ ) _{2 ,} and LiN(SO ₂ F) ₂ .

The content of the lithium salt may vary within a wide range. Preferably, the lithium ion battery has a lithium salt content of 0.1-15% in the nonaqueous electrolyte.

Another embodiment of the present invention discloses a lithium ion battery comprising a positive electrode, a negative electrode, and a lithium ion battery nonaqueous electrolyte as described above.

The positive electrode includes a positive electrode active material, and the active material of the positive electrode is LiNi _x Co _y MnzL _(1-xyz) O ₂ , LiCo _{x '} L _(1-x') O ₂ , LiNi _x" L'_y' Mn ₍ At least one of _2-x"-y') O ₄ , Li _{z '} MPO ₄ ; wherein L is at least one of Al, Sr, Mg, Ti, Ca, Zr, Zn, Si or Fe; ≤ x ≤ 1, 0 ≤ y ≤ 1, 0 ≤ z ≤ 1, 0 < x + y + z ≤ 1, 0 < x ' ≤ 1, 0.3 ≤ x" ≤ 0.6, 0.01 ≤ y' ≤ 0.2; L' It is at least one of Co, Al, Sr, Mg, Ti, Ca, Zr, Zn, Si, and Fe; 0.5 ≤ z' ≤ 1, and M is at least one of Fe, Mn, and Co.

The negative electrode includes a negative active material, which may be made of a carbon material, a metal alloy, a lithium-containing oxide, and a silicon-containing material.

In some embodiments, a separator is further disposed between the positive electrode and the negative electrode, and the separator is a conventional separator in the field of lithium ion batteries, and thus will not be described again.

The lithium ion battery provided by the embodiment of the invention has better high temperature cycle performance and high temperature storage performance because it contains the above nonaqueous electrolyte.

The invention is further illustrated by the following examples.

Example 1

This embodiment is used to illustrate the lithium ion battery non-aqueous electrolyte, the lithium ion battery and the preparation method thereof, and the following steps are included in the following steps:

Preparation of non-aqueous electrolyte: mixing ethylene carbonate (EC), diethyl carbonate (DEC) and ethyl methyl carbonate (EMC) by mass ratio EC:DEC:EMC=1:1:1, then adding Lithium hexafluorophosphate (LiPF ₆ ) to a molar concentration of 1 mol/L, and a component of the mass percentage shown in Table 1 was added in an amount of 100% based on the total mass of the nonaqueous electrolytic solution.

Preparation of positive electrode plate: mixed positive electrode active material lithium nickel cobalt manganese oxide LiNi _0.5 Co _0.2 Mn _0.3 O ₂ , conductive carbon black Super-P and binder polyvinylidene fluoride (PVDF) at a mass ratio of 93:4:3 Then, the mixture was dispersed in N-methyl-2-pyrrolidone (NMP) to obtain a positive electrode slurry. The positive electrode slurry was uniformly coated on both sides of the aluminum foil, dried, calendered and vacuum dried, and the aluminum lead wire was welded by an ultrasonic welder to obtain a positive electrode plate having a thickness of 120-150 μm.

Preparation of negative electrode plate: mixed negative electrode active material artificial graphite, conductive carbon black Super-P, binder styrene butadiene rubber (SBR) and carboxymethyl cellulose (CMC) at a mass ratio of 94:1:2.5:2.5, and then The mixture was dispersed in deionized water to obtain a negative electrode slurry. The negative electrode slurry was coated on both sides of the copper foil, dried, calendered, and vacuum dried, and the nickel lead wire was welded by an ultrasonic welder to obtain a negative electrode plate having a thickness of 120-150 μm.

Preparation of the separator: a three-layer separator was used, and the thickness was 20 μm.

Preparation of the battery cell: three layers of separator are placed between the positive electrode plate and the negative electrode plate, and then the sandwich structure composed of the positive electrode plate, the negative electrode plate and the separator is wound, and then the wound body is flattened and placed in an aluminum foil packaging bag. Bake at 85 ° C for 24 h under vacuum to obtain a cell to be injected.

The electrolyte prepared above was injected into the cell in a glove box with a dew point control below -40 ° C, and vacuum-packed and allowed to stand for 24 h.

Then follow the steps below to carry out the normalization of the first charge: 0.05C constant current charging for 180min, 0.2C constant current charging to 3.95V, secondary vacuum sealing, and then further constant current charging to 4.2V with 0.2C current, after standing at normal temperature for 24h The current was discharged at a constant current of 0.2 C to 3.0 V to obtain a 4.2 V LiNi _0.5 Co _0.2 Mn _0.3 O ₂ /artificial graphite lithium ion battery.

Examples 2 to 11

Embodiments 2 to 11 are for explaining the lithium ion battery nonaqueous electrolyte, the lithium ion battery and the preparation method thereof, and the method for preparing the same, including most of the operation steps in the embodiment 1, and the difference is:

In the non-aqueous electrolyte preparation step:

The non-aqueous electrolyte was added to the components of the mass percentages shown in Examples 2 to 11 of Table 1 based on 100% by mass of the total mass of the non-aqueous electrolyte.

Examples 12 to 14

Embodiments 12 to 14 are for explaining a lithium ion battery nonaqueous electrolyte, a lithium ion battery, and a preparation method thereof according to the present invention, and include most of the operation steps in Embodiment 1, the differences being:

In the non-aqueous electrolyte preparation step, the non-aqueous electrolyte is added to the group of the mass percentages shown in Examples 12 to 14 in Table 2, based on 100% of the total mass of the non-aqueous electrolyte. Minute.

In the preparation step of the positive electrode plate, LiCoO _{2 is} used as the active positive electrode material.

In the preparation step of the battery cell, the following steps are performed to perform the normalization of the first charging: 0.05 C constant current charging for 180 min, 0.2 C constant current charging to 3.95 V, secondary vacuum sealing, and then further charging with a constant current of 0.2 C. To 4.4V, after standing at room temperature for 24 hours, it was discharged at a constant current of 0.2 C to 3.0 V to obtain a 4.4 V LiCoO ₂ /artificial graphite lithium ion battery.

Comparative examples 1 to 6

Comparative Examples 1 to 6 are used for comparative description of the lithium ion battery nonaqueous electrolyte, the lithium ion battery and the preparation method thereof, and include most of the operation steps in Embodiment 1, the differences being:

In the non-aqueous electrolyte preparation step:

The non-aqueous electrolyte was added to the components of the mass percentages shown in Comparative Example 1 to Comparative Example 6 in Table 1 in terms of 100% by weight based on the total weight of the non-aqueous electrolyte.

Comparative example 7

Comparative Example 7 is used to compare and explain the lithium ion battery non-aqueous electrolyte, the lithium ion battery and the preparation method thereof, including the majority of the operation steps in Embodiment 1, except that:

In the non-aqueous electrolyte preparation step, the non-aqueous electrolyte solution is added to the mass percentage component shown in Comparative Example 7 in Table 2, based on 100% by weight of the total weight of the non-aqueous electrolyte solution.

In the preparation step of the positive electrode plate, LiCoO _{2 is} used as the active positive electrode material.

In the preparation step of the battery cell, the following steps are performed to perform the normalization of the first charging: 0.05 C constant current charging for 180 min, 0.2 C constant current charging to 3.95 V, secondary vacuum sealing, and then further charging with a constant current of 0.2 C. To 4.4V, after standing at room temperature for 24 hours, it was discharged at a constant current of 0.2 C to 3.0 V to obtain a 4.4 V LiCoO ₂ /artificial graphite lithium ion battery.

Performance Testing

The lithium ion batteries prepared in the above Examples 1 to 14 and Comparative Examples 1 to 7 were subjected to the following performance tests:

1) High temperature cycle performance test

At 45 ° C, the formed battery was charged to 4.2 V (LiNi _0.5 Co _0.2 Mn _0.3 O ₂ /artificial graphite battery) or 4.4 V (LiCoO ₂ /artificial graphite battery) with a constant current of 1 C, and the off current was 0.01. C, then discharged to 3.0V with a constant current of 1C. After the N cycles of charging/discharging, the retention of the capacity after the Nth cycle was calculated to evaluate the high temperature cycle performance.

The calculation formula of the N-time capacity retention rate at 45 °C 1C cycle is as follows:

The Nth cycle capacity retention ratio (%) = (the Nth cycle discharge capacity / the first cycle discharge capacity) × 100%.

2) 60 ° C high temperature storage performance test

The formed battery was charged to 4.2 V (LiNi _0.5 Co _0.2 Mn _0.3 O ₂ /artificial graphite battery) or 4.4 V (LiCoO ₂ /artificial graphite battery) at a normal temperature with a constant current of 1 C, and the off current was 0.01 C. Then use 1C constant current discharge to 3.0V, measure the initial discharge capacity of the battery, and then charge to 4.2V (LiNi _0.5 Co _0.2 Mn _0.3 O ₂ / artificial graphite battery) or 4.4V (LiCoO ₂ / artificial graphite) with 1C constant current and constant voltage. Battery), the off current is 0.01C, measure the initial thickness of the battery, then store the battery at 60 ° C for N days, measure the thickness of the battery, and then discharge to 3.0V with a constant current of 1C, measure the holding capacity of the battery, and then use 1C constant Flow constant voltage charging to 4.2V (LiNi _0.5 Co _0.2 Mn _0.3 O ₂ / artificial graphite battery) or 4.4V (LiCoO ₂ / artificial graphite battery), the off current is 0.01C, and then discharged to 3.0V with 1C constant current, measuring Restore capacity. The formula for calculating the capacity retention rate and capacity recovery rate is as follows:

Battery capacity retention rate (%) = retention capacity / initial capacity × 100%;

Battery capacity recovery rate (%) = recovery capacity / initial capacity × 100%;

Battery thickness expansion ratio (%) = (thickness after N days - initial thickness) / initial thickness × 100%.

The test results obtained are filled in Tables 1 and 2.

Table 1 The positive active materials are all LiNi _0.5 Co _0.2 Mn _0.3 O ₂

Table 2 The positive active materials are all LiCoO ₂

It can be seen from the test results of Examples 1 to 14 and Comparative Examples 1 to 7 in Tables 1 and 2 that the addition of the compound of Structural Formula 1 provided by the present invention to the non-aqueous electrolyte can effectively improve the high temperature cycle of the battery. Performance and high temperature storage performance.

From the test results of Table 1, it is known that in the electrolyte system of vinylene carbonate, fluoroethylene carbonate, 1,3-propane sultone, or LiN(SO ₂ F) ₂ , the structural formula 1 is added. The compound's high temperature cycle performance and high temperature storage performance have been further improved.

The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. Within the scope.

Claims (10)

1. A lithium ion battery nonaqueous electrolyte characterized by comprising a solvent, a lithium salt, and one or more selected from the group consisting of compounds of Structural Formula 1;

   

   In Structural Formula 1, R is a single bond or a methylene group; R _{1 is} selected from

   

   

   R ₂ and R ₃ are each independently selected from hydrogen or halogen; and m is selected from an integer of 1 to 4, and n is selected from an integer of 0 to 2.
2. The nonaqueous electrolyte for a lithium ion battery according to claim 1, wherein the compound represented by Structural Formula 1 is selected from the group consisting of the following compounds:

   
3. The nonaqueous electrolyte for a lithium ion battery according to claim 1, wherein the mass percentage of the compound represented by the structural formula 1 is 100% based on the total mass of the nonaqueous electrolyte of the lithium ion battery. It is 0.1% to 5%.
4. The nonaqueous electrolyte for a lithium ion battery according to claim 1, wherein the nonaqueous electrolyte further comprises an unsaturated cyclic carbonate, a fluorinated cyclic carbonate, a cyclic sultone and a ring. One or more of the sulfates.
5. The nonaqueous electrolyte for a lithium ion battery according to claim 4, wherein the unsaturated cyclic carbonate comprises one of vinylene carbonate, ethylene carbonate, and methylene ethylene carbonate. Multiple

   The fluorinated cyclic carbonate includes one or more of fluoroethylene carbonate, trifluoromethyl ethylene carbonate, and difluoroethylene carbonate;

   The cyclic sultone lactone includes one or more of 1,3-propane sultone, 1,4-butane sultone and propylene-1,3- sultone;

   The cyclic sulfate is selected from one or more of the group consisting of vinyl sulfate and 4-methylsulfate.
6. The nonaqueous electrolyte for a lithium ion battery according to claim 4 or 5, wherein the content of the unsaturated cyclic carbonate in the nonaqueous electrolytic solution is 0.01% to 10%; the fluorocyclic carbonate The content is 0.01%-30%; the content of the cyclic sultone is 0.01%-10%; and the content of the cyclic sulfate is 0.01%-10%.
7. The nonaqueous electrolyte for a lithium ion battery according to claim 1, wherein the solvent is a mixture of a cyclic carbonate and a chain carbonate;

   The cyclic carbonate is selected from one or more of the group consisting of ethylene carbonate, propylene carbonate, and butylene carbonate;

   The chain carbonate is selected from one or more of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and methyl propyl carbonate.
8. The nonaqueous electrolyte for a lithium ion battery according to claim 1, wherein the lithium salt is selected from the group consisting of LiPF ₆ , LiBF ₄ , LiBOB, LiDFOB, LiN(SO ₂ CF ₃ ) ₂ and LiN(SO ₂ F). one or more of the _two.
9. A lithium ion battery comprising a positive electrode, a negative electrode, and a lithium ion battery nonaqueous electrolyte according to any one of claims 1-8.
10. The lithium ion battery according to claim 9, wherein the positive electrode comprises a positive electrode active material, and the active material of the positive electrode is LiNi _x Co _y MnzL _(1-xyz) O ₂ , LiCo _x' L _{(1- x') at least one of} O ₂ , LiNi _x" L'_y' Mn _(2-x"-y') O ₄ , Li _{z '} MPO ₄ ; wherein L is Al, Sr, Mg, Ti, Ca At least one of Zr, Zn, Si or Fe; 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, 0 ≤ z ≤ 1, 0 < x + y + z ≤ 1, 0 <x' ≤ 1, 0.3 ≤ x" ≤ 0.6, 0.01 ≤ y' ≤ 0.2; L' is at least one of Co, Al, Sr, Mg, Ti, Ca, Zr, Zn, Si, Fe; 0.5 ≤ z' ≤ 1, M is At least one of Fe, Mn, and Co.