阅读说明：本技术 一种锂离子电池 (Lithium ion battery ) 是由 胡时光 钱韫娴 张正生 向晓霞 邓永红 于 2021-07-30 设计创作，主要内容包括：本发明涉及电化学技术领域,具体涉及一种锂离子电池,包括正极、负极和电解液,正极包括正极活性材料和导电剂；正极活性材料为含锰正极材料；电解液包括下述结构式1所示的化合物：正极活性材料、导电剂和结构式1所示的化合物满足如下关系：其中,Dr和Tr分别为正极活性材料与导电剂的平均粒径及比表面积的比值；w为结构式1所示的化合物相对于电解液的质量百分比,单位为％。本发明在调控正极活性材料与导电剂的比表面积及粒径比的情况下,在电解液中加入结构式1所示的化合物,三者之间通过界面协同效应强化正极材料的结构,同时弱化正极材料与电解液间的界面阻抗,减少锰的溶出,使锂电池具有良好的高温存储性能和高温循环性能。(The invention relates to the technical field of electrochemistry, in particular to a lithium ion battery which comprises a positive electrode, a negative electrode and electrolyte, wherein the positive electrode comprises a positive active material and a conductive agent; the positive electrode active material is a manganese-containing positive electrode material; the electrolyte includes a compound represented by the following structural formula 1: the positive electrode active material, the conductive agent, and the compound represented by structural formula 1 satisfy the following relationship:)

1. A lithium ion battery comprises a positive electrode, a negative electrode and electrolyte, and is characterized in that the positive electrode comprises a positive active material and a conductive agent;

the positive electrode active material is a manganese-containing positive electrode material;

the electrolyte includes a compound represented by the following structural formula 1:

wherein R is₁、R₂、R₃、R₄、R₅、R₆Each independently selected from one of hydrogen atom, fluorine atom or group containing 1-5 carbon atoms;

the positive electrode active material, the conductive agent, and the compound represented by the structural formula 1 satisfy the following relationship:

wherein Dr is a ratio of an average particle diameter of the positive electrode active material to an average particle diameter of the conductive agent; tr is a ratio of a specific surface area of the positive electrode active material to a specific surface area of the conductive agent; w is the mass percentage of the compound shown in the structural formula 1 relative to the electrolyte, and the unit is%.

2. The lithium ion battery according to claim 1, wherein the mass percentage w of the compound represented by the structural formula 1 relative to the electrolyte is 100% of the total mass of the electrolyte and satisfies: w is more than or equal to 0.1 percent and less than or equal to 5 percent.

3. The lithium ion battery according to claim 1, wherein a ratio Dr of an average particle diameter of the positive electrode active material to an average particle diameter of the conductive agent satisfies: dr is more than or equal to 1.3 and less than or equal to 3.8; a ratio Tr of a specific surface area of the positive electrode active material to a specific surface area of the conductive agent satisfies: tr is more than or equal to 0.25 and less than or equal to 1.

4. The lithium ion battery according to claim 3, wherein a ratio Dr of an average particle diameter of the positive electrode active material to an average particle diameter of the conductive agent satisfies: dr is more than or equal to 1.5 and less than or equal to 2.5; a ratio Tr of a specific surface area of the positive electrode active material to a specific surface area of the conductive agent satisfies: tr is more than or equal to 0.3 and less than or equal to 0.8.

5. The lithium ion battery according to claim 1, wherein the compound represented by the structural formula 1 comprises the following compounds:

6. the lithium ion battery of claim 1, wherein the positive electrode active material is selected from one or more of the following materials:

spinel LiMn₂O₄；

LiNi_xMn_yO₄Wherein x is more than or equal to 0.5<1，1.5≤y<2.0；

LiNi_zMn_1-zO₂Wherein z is more than or equal to 0.1<1；

aLi₂MnO₃·(1-a)LiMO₂Wherein 0 is<a is less than or equal to 1, and M is selected from one or more of Ni, Co and Mn.

7. The lithium ion battery of claim 1, wherein the conductive agent is selected from one or more of acetylene black, SuperP, graphene, Ketjen black, SFG-6, carbon nanotubes, and graphdine.

8. The lithium ion battery of claim 1, wherein the electrolyte further comprises a lithium salt, the lithium saltSelected from LiPF₆、LiPO₂F₂、LiBF₄、LiBOB、LiSbF₆、LiAsF₆、LiCF₃SO₃、LiDFOB、LiN(SO₂CF₃)₂、LiC(SO₂CF₃)₃、LiN(SO₂C₂F₅)₂、LiN(SO₂F)₂、LiCl、LiBr、LiI、LiClO₄、LiBF₄、LiB₁₀Cl₁₀、LiAlCl₄And LiBETI.

9. The lithium ion battery of claim 1, wherein the electrolyte further comprises one or more of a cyclic sulfate compound, a cyclic sulfonate compound, and a cyclic carbonate compound;

the cyclic sulfate compound comprises one or more of vinyl sulfate, allyl sulfate or methyl vinyl sulfate;

the cyclic sulfonate compound comprises one or more of 1, 3-propane sultone, 1, 4-butane sultone and 1, 3-propylene sultone;

the cyclic carbonate compound comprises one or more of vinylene carbonate, ethylene carbonate, methylene ethylene carbonate, fluoroethylene carbonate, trifluoromethyl ethylene carbonate and difluoroethylene carbonate.

10. The lithium ion battery of claim 1, wherein the electrolyte further comprises a non-aqueous organic solvent comprising at least one of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, or propyl methyl carbonate.

Technical Field

The invention relates to the technical field of electrochemistry, in particular to a lithium ion battery.

Background

Lithium ion batteries, as the main product of the fourth industrial revolution, mark the global entrance into a new era with new energy as the theme. The lithium ion battery has the advantages of high working voltage, wide working range, large specific energy, no pollution, long service life and the like, occupies a leading position in the global secondary battery market, and is widely applied to the fields of electric automobiles and the like in recent years. In the lithium ion battery technology, the positive electrode material is a decisive factor of the lithium ion voltage and the capacity, and determines the ceiling of the lithium battery capacity.

In the prior art, spinel lithium manganate, high-nickel cobalt-free and lithium-rich manganese materials and the like which are novel materials are widely used as the anode of lithium ion battery materials due to the advantages of wide voltage bearing window, large capacity and the like. But meanwhile, when the materials are used as a battery material anode, the common problems of the materials are that: poor conductivity, easy dissolution of manganese ions, easy collapse of the structure of the positive electrode material and the like. The specific reasons are as follows: in terms of microstructure, the crystal structure of the material has abundant lithium ion transmission channels, and simultaneously, manganese ions are respectively positioned on crystal structure points, so that the material plays an important role in the structural stability of crystals; in the aspect of electrochemical performance, the voltage window is wider, and the multiplying power performance is good under a certain condition; in the high-temperature circulation process, the anode active material has a certain catalytic action on the electrolyte, so that the catalytic oxidation of the electrolyte is caused, lattice oxygen is further lost,the dissolution of manganese ions is initiated to cause the structural collapse of the anode material, and the performance of the battery is influenced; mn in positive electrode active material³⁺Easily disproportionate with HF in electrolyte to generate Mn²⁺And Mn⁴⁺Dissolving bivalent manganese to destroy the structure of the positive electrode material; in the course of charging, Mn²⁺Migration to the negative electrode, deposition causing short circuits; when the average valence of manganese in the anode material is lower than +3.5, the crystal structure of the anode material is transformed from a stable structure to an unstable structure, so that the polarization effect of the electrode is enhanced, and the defects of capacity attenuation, poor conductivity and the like are caused.

At present, many researchers add a conductive agent into a positive electrode material to enhance the conductivity of the positive electrode material, and the conductivity is improved to a certain extent, for example, carbon coating is performed on the surface of spinel lithium nickel manganese oxide to enhance the conductivity of the positive electrode, or nano LiFePO is constructed on the surface of a lithium iron phosphate positive electrode material₄And crystal grains for reducing diffusion distance of lithium ions in the crystal grains to enhance diffusion of the lithium ions. However, while solving the problem of positive electrode conductivity, a series of problems are introduced: the addition of the conductive agent leads the stability of the positive electrode to be poor, manganese ions are dissolved out more easily, the diffusion rate of lithium ions is further weakened, and meanwhile, the compatibility between the positive electrode material and the electrolyte is further poor, so that the cycle performance and the storage performance of the battery are deteriorated under the high-temperature condition. Therefore, how to develop a lithium ion battery that can solve both the problem of positive electrode conductivity and a series of problems caused thereby is a technical problem to be solved in the field.

Disclosure of Invention

In order to solve the problems, the invention provides a lithium ion battery, and under the condition of regulating and controlling the specific surface area and the particle diameter ratio of a positive electrode active material and a conductive agent, the compound shown in the structural formula 1 is added into an electrolyte, so that the stability of the positive electrode material can be enhanced on the basis of ensuring and improving the conductive performance, and the compatibility problem of the positive electrode material and an electrolyte can be obviously improved.

A lithium ion battery comprises a positive electrode, a negative electrode and an electrolyte, wherein the positive electrode comprises a positive active material and a conductive agent;

the positive electrode active material is a manganese-containing positive electrode material;

the electrolyte includes a compound represented by the following structural formula 1:

wherein R is₁、R₂、R₃、R₄、R₅、R₆Each independently selected from one of hydrogen atom, fluorine atom or group containing 1-5 carbon atoms;

the positive electrode active material, the conductive agent, and the compound represented by the structural formula 1 satisfy the following relationship:

wherein Dr is a ratio of an average particle diameter of the positive electrode active material to an average particle diameter of the conductive agent; tr is a ratio of a specific surface area of the positive electrode active material to a specific surface area of the conductive agent; w is the mass percentage of the compound shown in the structural formula 1 relative to the electrolyte, and the unit is%.

According to the lithium ion battery, the compound shown in the structural formula 1 is added into the electrolyte, the particle diameter ratio and the specific surface area ratio between the conductive agent and the positive active material are regulated and controlled, and the addition amount of the compound shown in the structural formula 1 is controlled, so that the performance of the battery can be optimized and improved to the maximum extent, the connection between the electrolyte interface strengthening conductive agent and the positive active material is fully exerted, and the structure of the positive material is more stable on the basis of ensuring the conductive performance.

Specifically, it is assumed that the compound represented by formula 1 can be decomposed on the positive electrode to form a specific film, and the film and a specific conductive agent with a regular size can enhance the stability of the positive electrode material in the positive electrode active material through an interfacial synergistic effect, so that a stable conductive network can be formed between the conductive agent and the positive electrode active material, and a lithium ion transport channel can be enhanced. The positive electrode material is used in a high-voltage system, manganese ions can be easily dissolved out due to the characteristic of the manganese-rich system, and the compound shown in the structural formula 1 forms a barrier of metal ions (except lithium ions) between the positive electrode material and an electrolyte, so that the compound can perform a complexing action on the manganese ions, and can inhibit the dissolution of the manganese ions from the positive electrode and the deposition of the manganese ions on the negative electrode; the occurrence of side reactions and the loss of electrolyte are reduced, so that the high-temperature cycle performance of the battery is obviously improved; the compound shown in the structural formula 1 can weaken the interface impedance between the anode material and the electrolyte, realize the protection of the anode material and the cathode material, and simultaneously can obviously reduce the ballooning effect of the battery under the high-temperature condition, thereby improving the high-temperature storage performance and the high-temperature cycle performance of the battery.

Preferably, the positive electrode active material, the conductive agent, and the compound represented by structural formula 1 satisfy the following relationship:

preferably, the group containing 1 to 5 carbon atoms is one selected from a hydrocarbon group, a halogenated hydrocarbon group, an oxygen-containing hydrocarbon group, a silicon-containing hydrocarbon group and a cyano-containing hydrocarbon group.

Preferably, R₁、R₂、R₃、R₄、R₅、R₆Each independently selected from one of a hydrogen atom, a fluorine atom, a methyl group, an ethyl group, a trimethylsiloxy group, a cyano group or a trifluoromethyl group.

Preferably, the compound represented by the structural formula 1 includes the following compounds:

further, the mass percentage w of the compound shown in the structural formula 1 relative to the electrolyte is 100 percent of the total mass of the electrolyte, and satisfies the following condition: w is more than or equal to 0.1 percent and less than or equal to 5 percent. Preferably, the mass percentage w of the compound represented by the structural formula 1 relative to the electrolyte satisfies: w is more than or equal to 0.1 percent and less than or equal to 2 percent.

Further, a ratio Dr of the average particle diameter of the positive electrode active material to the average particle diameter of the conductive agent satisfies: dr is more than or equal to 1.3 and less than or equal to 3.8; a ratio Tr of a specific surface area of the positive electrode active material to a specific surface area of the conductive agent satisfies: tr is more than or equal to 0.25 and less than or equal to 1. Preferably, a ratio Dr of the average particle diameter of the positive electrode active material to the average particle diameter of the conductive agent satisfies: dr is more than or equal to 1.5 and less than or equal to 2.5; a ratio Tr of a specific surface area of the positive electrode active material to a specific surface area of the conductive agent satisfies: tr is more than or equal to 0.3 and less than or equal to 0.8.

Further, the average particle size of the positive electrode active material is 1-10 μm, and the average particle size of the conductive agent is smaller than 8 μm. Preferably, the average particle size of the positive electrode active material is 2-7 μm, and the average particle size of the conductive agent is less than 3 μm.

Further, the specific surface area of the positive active material is 0.5-1.5 m²The specific surface area of the conductive agent is 1.5-20 m²/g。

Further, the positive active material is selected from one or more of the following materials:

spinel LiMn₂O₄；

LiNi_xMn_yO₄Wherein x is more than or equal to 0.5<1，1.5≤y<2.0；

LiNi_zMn_1-zO₂Wherein z is more than or equal to 0.1<1；

aLi₂MnO₃·(1-a)LiMO₂Wherein 0 is<a is less than or equal to 1, and M is selected from one or more of Ni, Co and Mn.

Further, the conductive agent is selected from one or more of acetylene black, SuperP, graphene, Ketjen black, SFG-6, carbon nanotubes and graphdine.

Further, the negative electrode comprises a negative active material, and the negative active material comprises one or more of a carbon-based negative electrode, a silicon-based negative electrode, a tin-based negative electrode, and a lithium negative electrode.

Further, the positive electrode conductive agent and the negative electrode conductive agent may be the same or different, and those skilled in the art may select a suitable conductive agent material according to the specific application.

Further, the electrolyte also comprises a lithium salt, and the lithium salt is selected from LiPF₆、LiPO₂F₂、LiBF₄、LiBOB、LiSbF₆、LiAsF₆、LiCF₃SO₃、LiDFOB、LiN(SO₂CF₃)₂、LiC(SO₂CF₃)₃、LiN(SO₂C₂F₅)₂、LiN(SO₂F)₂、LiCl、LiBr、LiI、LiClO₄、LiBF₄、LiB₁₀Cl₁₀、LiAlCl₄And LiBETI.

Further, the electrolyte also comprises one or more of cyclic sulfate compounds, cyclic sulfonate compounds and cyclic carbonate compounds;

preferably, the cyclic sulfate compound comprises one or more of vinyl sulfate, allyl sulfate or vinyl methyl sulfate; the mass percent is 0.01-10%, preferably 0.1-5.0%.

The cyclic sulfonate compound comprises one or more of 1, 3-propane sultone (1,3-PS), 1, 4-Butane Sultone (BS) and 1, 3-Propylene Sultone (PST); the mass percent is 0.01-10%, preferably 0.1-5.0%.

The cyclic carbonate compound comprises one or more of Vinylene Carbonate (VC), ethylene carbonate (VEC), methylene ethylene carbonate, fluoroethylene carbonate (FEC), trifluoromethyl ethylene carbonate and difluoroethylene carbonate; the mass percent of the methylene ethylene carbonate, VC and VEC is 0.01-10%, preferably 0.1-5.0%; the mass percentage of FEC, trifluoromethyl ethylene carbonate and difluoroethylene carbonate is 0.01-30%, preferably 0.1-5%.

Further, the electrolyte also comprises a non-aqueous organic solvent, and the non-aqueous organic solvent comprises at least one of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate or propyl methyl carbonate.

Furthermore, the lithium ion battery further comprises a separator arranged between the positive electrode and the negative electrode, and the separator can be any known separator, which is not limited in the invention.

Furthermore, the voltage interval of the lithium ion battery is between 2.0V and 4.8V.

Compared with the prior art, the invention achieves the following beneficial effects:

according to the lithium ion battery, the compound shown in the structural formula 1 is added into the electrolyte, the ratio of the particle diameter ratio of the conductive agent to the positive active material and the ratio of the specific surface area are regulated, the addition amount of the compound shown in the structural formula 1 is controlled, the performance of the battery can be optimized and improved to the maximum extent, the contact between the electrolyte interface and the positive active material is fully exerted, the structure of the positive material is more stable on the basis of ensuring the conductive performance, the dissolution of manganese is reduced, and therefore the high-temperature storage performance and the high-temperature cycle performance of the battery are improved.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The present invention will be further illustrated by the following examples.

TABLE 1

Note: the compounds used in the following examples and comparative examples were selected from table 1.

Example 1

Preparation of lithium ion battery

(1) Preparation of the electrolyte

Ethylene Carbonate (EC), diethyl carbonate (DEC) and Ethyl Methyl Carbonate (EMC) were mixed in a mass ratio of EC: DEC: EMC ═ 1:1:1, and then lithium hexafluorophosphate (LiPF) was added₆) To a molar concentration of 1mol/L, the compound of formula 1 was added in an amount shown in example 1 of Table 1.

(2) Preparation of Positive plate

LiNi, a positive electrode active material, was mixed in a mass ratio of 93:4:3_0.5Mn_1.5O₄Conductive carbon black Super-P and a binder polyvinylidene fluoride (PVDF), and then dispersed in N-methyl-2-pyrrolidone (NMP) to obtain a positive electrode slurry. And uniformly coating the slurry on two sides of the aluminum foil, drying, rolling and vacuum drying, and welding an aluminum outgoing line by using an ultrasonic welding machine to obtain the positive plate, wherein the thickness of the positive plate is 120-.

(3) Preparation of negative plate

Mixing artificial graphite serving as a negative electrode active material, conductive carbon black Super-P, Styrene Butadiene Rubber (SBR) serving as a binder and carboxymethyl cellulose (CMC) according to a mass ratio of 94:1:2.5:2.5, and dispersing the materials in deionized water to obtain negative electrode slurry. Coating the slurry on two sides of the copper foil, drying, rolling and vacuum drying, and welding a nickel outgoing line by using an ultrasonic welding machine to obtain a negative plate, wherein the thickness of the negative plate is 120-150 mu m.

(4) Preparation of cell

And placing three layers of polypropylene microporous diaphragms with the thickness of 20 mu m between the positive plate and the negative plate, then winding the sandwich structure consisting of the positive plate, the negative plate and the diaphragms, flattening the wound body, then placing the flattened wound body into an aluminum foil packaging bag, and baking the flattened wound body in vacuum at 75 ℃ for 48 hours to obtain the battery cell to be injected with liquid.

(5) Liquid injection and formation of battery core

And (3) in a glove box with the dew point controlled below-40 ℃, injecting the prepared electrolyte into the battery cell, carrying out vacuum packaging, and standing for 24 hours.

LiNi_0.5Mn_1.5O₄The battery is subjected to the first charging routine according to the following steps: charging at 0.05C for 180min, charging at 0.2C to 3.85V, vacuum sealing for the second time, further charging at 0.2C to 4.4V, standing at room temperature for 24hr, and discharging at 0.2C to 3.0V.

Second, testing the battery performance

(1) High temperature cycle performance test

The cell was placed in an oven at a constant temperature of 45 ℃ and charged to 4.4V (LiNi) with a constant current of 1C_0.5Mn_1.5O₄Artificial graphite battery), then charged at constant voltage until the current drops to 0.02C, and then discharged at constant current of 1C to 3.0V. The 1 st discharge capacity and the last discharge capacity were recorded in this cycle, and the capacity retention rate in the high-temperature cycle was calculated as follows:

capacity retention (%) — last discharge capacity/1 st discharge capacity × 100%;

(2) high temperature storage Performance test

The lithium ion battery after being formed is charged to 4.4V (LiNi) by a 1C constant current and a constant voltage at normal temperature_0.5Mn_1.5O₄Artificial graphite battery), and then discharged to 3V at 1C after storage for 30 days in an environment of 60C, and the retention capacity and recovery capacity of the battery and the thickness of the battery after storage were measured. The calculation formula is as follows:

battery capacity retention (%) — retention capacity/initial capacity × 100%;

battery capacity recovery (%) — recovery capacity/initial capacity × 100%;

thickness expansion (%) (battery thickness after storage-initial battery thickness)/initial battery thickness × 100%.

Examples 2 to 16

Examples 2-16 are intended to illustrate a lithium ion battery of the present disclosure, including most of the operating steps of example 1, with the following differences:

the compound represented by the structural formula 1 in the content shown in table 1 was added during the preparation of the electrolyte, and the average particle diameter ratio and specific surface area ratio of the positive electrode active material and the conductive agent during the preparation of the positive electrode plate are shown in table 2. The test results are shown in Table 3.

Comparative examples 1 to 4

Comparative examples 1-4 are illustrative of lithium ion batteries of the present disclosure, including most of the operating steps of example 1, with the following exceptions:

the compound represented by the structural formula 1 in the content shown in table 1 was added during the preparation of the electrolyte, and the average particle diameter ratio and specific surface area ratio of the positive electrode active material and the conductive agent during the preparation of the positive electrode plate are shown in table 2. The test results are shown in Table 3.

TABLE 2 compositions of lithium ion batteries in examples 1-16 and comparative examples 1-4

Table 4 electrochemical performance test results of the lithium ion batteries of examples 1 to 16 and comparative examples 1 to 4

As seen from examples 1 to 16 and comparative examples 1 to 4, the compound represented by the formula 1 was added to the electrolyte, and the average particle diameter ratio and the specific surface area ratio between the positive electrode active material and the conductive agent were adjusted so as to satisfy the requirement for the addition amount of the compound represented by the formula 1 to the addition amount of the compound represented by the formula 1When it is needed toThe stability of the anode material is strengthened on the basis of ensuring the improvement of the conductivity, and the compatibility problem of the anode material and the electrolyte is obviously improved. The addition of the compound shown in the structural formula 1 constructs a barrier for metal ion dissolution between the electrolyte and the anode material, so that the problem of manganese ion dissolution can be obviously improved, and the high-temperature cycle and storage performance of the battery can be obviously improved. Preferably, when it is satisfiedThe compound of formula 1 may have a moderate specific film thickness formed at the positive electrode and may have an optimal synergistic effect with the conductive agent in the positive electrode active material.

Examples 17 to 21

Examples 17-21 illustrate a lithium ion battery of the present disclosure, including most of the operating steps of example 1, with the following differences:

during the preparation of the electrolyte, different compounds of formula 1 were added in the amounts shown in examples 17-21 in Table 4. The results are shown in Table 5.

TABLE 4 lithium ion battery compositions of examples 3, 17-21

Table 5 electrochemical performance test results of lithium ion batteries of examples 3, 17 to 21

Examples 22 to 25

Examples 22-25 illustrate a lithium ion battery of the present disclosure, including most of the operating steps of example 1, with the following exceptions:

the positive electrode active materials shown in examples 22 to 25 in table 6 were added during the preparation of the positive electrode. The results are shown in Table 7.

TABLE 6 lithium ion cell compositions of examples 3, 22-25

Table 7 electrochemical performance test results of the lithium ion batteries of examples 3, 22 to 25

From the test results, the compound shown in the structural formula 1 is matched with the traditional Vinylene Carbonate (VC), fluoroethylene carbonate (FEC), vinyl sulfate (DTD) and 1, 3-Propane Sultone (PS) for use, so that the high-temperature performance of the lithium ion battery can be further improved.

Examples 26 to 34

Examples 26-34 are provided to illustrate a lithium ion battery of the present disclosure, including most of the operating steps of example 1, with the following differences:

the positive electrode active materials and additives shown in examples 26 to 34 in table 8 were added during the preparation of the positive electrode. The results are shown in Table 9.

Comparative examples 5 to 10

Comparative examples 5-10 illustrate a lithium ion battery of the present disclosure, including most of the operating steps of example 1, except that:

the substances added during the preparation of the electrolyte are shown in table 8. The results are shown in Table 9.

TABLE 8 compositions of lithium ion batteries of examples 26-34 and comparative examples 5-10

TABLE 9 electrochemical Performance test results of the lithium ion batteries of examples 26 to 34 and comparative examples 5 to 10

According to test results, the lithium ion battery provided by the invention has a good matching effect with different manganese-containing cathode active materials due to the fact that the compound shown in the structural formula 1 is added into the electrolyte, the average particle diameter ratio and the specific surface area ratio between the cathode active material and the conductive agent are regulated, and the dissolution of Mn ions can be effectively inhibited only by regulating the relation between the average particle diameter ratio and the specific surface area ratio between the cathode active material and the conductive agent and the content of the compound shown in the structural formula 1, so that the high-temperature cycle performance and the high-temperature storage performance of the lithium ion battery are improved.

In summary, the invention provides a lithium ion battery, under the condition of regulating and controlling the specific surface area and the particle diameter ratio of the positive electrode active material and the conductive agent, the compound shown in the structural formula 1 with specific content is added into the electrolyte, so as to meet the requirement of regulating and controlling the specific surface area and the particle diameter ratio of the positive electrode active material and the conductive agentIn the relation, the structure of the positive electrode material is strengthened by the interface synergistic effect between the compound shown in the structural formula 1 and the added conductive agent as well as the positive electrode material, the interface impedance between the positive electrode material and the electrolyte is weakened, the lithium ion mobility is effectively improved, and the lithium battery has good rate capability, high-temperature storage performance and high-temperature cycle performance under the condition that the conductivity of the battery is not deteriorated.

The present invention has been further described with reference to specific embodiments, but it should be understood that the detailed description should not be construed as limiting the spirit and scope of the present invention, and various modifications made to the above-described embodiments by those of ordinary skill in the art after reading this specification are within the scope of the present invention.