A lithium-ion battery

Abstract

To overcome the problem of Mn ion dissolution caused by changes in the valence level of Mn in the positive electrode of existing lithium-ion batteries, this invention provides a lithium-ion battery comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte. The positive electrode includes a positive electrode material layer containing a positive electrode active material, wherein the positive electrode active material comprises a manganese-containing positive electrode material, and the specific surface area of ​​the positive electrode active material is 0.5–1.5 m². 2 / g, the non-aqueous electrolyte comprises a non-aqueous organic solvent, additives, and a lithium salt, wherein the additives comprise compounds shown in structural formula 1; the lithium-ion battery satisfies the following conditions: 0.5≤(Vr / Vr*) / Wr≤12, and 0.4≤Vr / Vr*≤1.5, 0.1≤Wr≤3. The lithium-ion battery provided by this invention can effectively suppress the irreversible change in the valence of manganese ions during battery cycling of manganese-containing cathode materials, thereby reducing the dissolution of manganese ions from manganese-containing cathode materials.

Description

Technical Field

[0001] This invention belongs to the field of energy storage device technology, and specifically relates to a lithium-ion battery. Background Technology

[0002] Lithium-ion batteries boast advantages such as high operating voltage, high energy density, good safety performance, low self-discharge, fast charging capability, wide operating range, and long service life, dominating the global rechargeable battery market. In recent years, new energy electric vehicles have reached their peak of development. In lithium-ion battery technology, the cathode material is the decisive factor for lithium-ion voltage and capacity, determining the ceiling of lithium battery capacity, while the electrolyte is the lifeblood of the lithium battery to achieve the required capacity. However, regardless of whether it is a high-voltage system or a high-nickel system, ensuring the stability of the cathode material framework is a necessary condition for achieving its capacity ceiling. Macroscopic stability is determined by the microstructure of the cathode active material, such as the valence state of metal ions in the cathode material and the coordination state of the cathode metal ions with oxygen. Changes in these microscopic parameters can characterize the stability state of the cathode material. Currently, during the lithium insertion / extraction process of cathode materials, when lithium is inserted / extracted to a certain extent, the phase transition makes the cathode material framework unstable, and high-valence metal ions in the cathode are easily extracted. For example, during the charging process of lithium-ion batteries containing manganese-based cathodes, manganese dissolves, as Mn... 2+ The form migrates to the negative electrode and deposits there, causing a short circuit. In high-voltage and high-nickel systems, there is poor compatibility between the positive electrode material and the electrolyte, which is detrimental to lithium-ion transfer. The electrolyte provides poor protection for the positive electrode active material, exposing high-valence metal ions. These exposed high-valence metal ions have a catalytic effect on the electrolyte, causing catalytic oxidation and leading to lattice oxygen loss. This triggers the dissolution of Mn ions, causing structural collapse of the positive electrode active material and affecting battery performance. Furthermore, when the average valence of Mn is below +3.5, the crystal structure of the positive electrode active material transforms from a stable to an unstable structure, increasing electrode polarization and causing capacity decay and poor conductivity. Currently, many researchers are trying to enhance the conductivity of positive electrode active materials by adding conductive agents. While this improves conductivity to some extent, it also leads to a series of problems. The addition of conductive agents makes the stability of the positive electrode worse, makes Mn ions more easily dissolved, and further weakens the diffusion rate of lithium ions. At the same time, the compatibility between the positive electrode active material and the electrolyte becomes worse, which in turn degrades the cycle performance and storage performance of the battery under high and low temperature conditions. Summary of the Invention

[0003] To address the problem of Mn ion dissolution caused by changes in the valence of Mn in the cathode of existing lithium-ion batteries, this invention provides a lithium-ion battery.

[0004] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0005] This invention provides a lithium-ion battery, comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte. The positive electrode includes a positive electrode material layer containing a positive electrode active material, wherein the positive electrode active material includes a manganese-containing positive electrode material, and the specific surface area of ​​the positive electrode active material is 0.5–1.5 m². 2 / g, the non-aqueous electrolyte comprises a non-aqueous organic solvent, additives, and a lithium salt, wherein the additives comprise compounds represented by structural formula 1:

[0006]

[0007] Where n is 0 or 1, and X is selected from... R1 and R2 are each independently selected from H, halogens, and unsubstituted or halogenated C1-C5 hydrocarbon groups. And at least one sulfur atom is present in X, R1, and R2;

[0008] The lithium-ion battery meets the following conditions:

[0009] 0.5≤(Vr / Vr*) / Wr≤12, and 0.4≤Vr / Vr*≤1.5, 0.1≤Wr≤3;

[0010] Where Vr is the specific surface area of ​​the micropores in the positive electrode active material, in m³. 2 / g;

[0011] Vr* represents the mesoporous specific surface area of ​​the positive electrode active material, in m³. 2 / g;

[0012] Wr represents the mass percentage of the compound shown in structural formula 1 in the non-aqueous electrolyte, expressed as %.

[0013] Optionally, the lithium-ion battery meets the following conditions:

[0014] 1≤(Vr / Vr*) / Wr≤10.

[0015] Optionally, the ratio of the microporous specific surface area to the mesoporous specific surface area of ​​the positive electrode active material, Vr / Vr*, is 0.5 to 1.2.

[0016] Optionally, the microporous specific surface area Vr of the positive electrode active material is 0.2–0.7 m². 2 / g.

[0017] Optionally, the mesoporous specific surface area Vr* of the positive electrode active material is 0.14–1.4 m². 2 / g.

[0018] Optionally, the mass percentage Wr of the compound represented by structural formula 1 in the non-aqueous electrolyte is 0.1% to 2%.

[0019] Optionally, under the condition of 500 cycles at a high temperature of 40-60°C in the lithium-ion battery, the valence ratio of metal ions Mn in the positive electrode active material is 0.1 ≤ M 2+* / M 4+* ≤0.4, where M 2+* For Mn 2+ Content, M 4+* For Mn 4+ The content of.

[0020] Optionally, the compound represented by structural formula 1 includes at least one of the following compounds:

[0021]

[0022]

[0023] Optionally, the manganese-containing cathode material is selected from LiNi. x Co y Mn z L (1-x-y-z) At least one of O2, wherein L is Al, Sr, Mg, Ti, Ca, Zr, Zn, Si, Cu, V or Fe, and 0 <x≤1,0≤y≤1,0<z ≤1,0<x+y+z≤1。

[0024] Optionally, the additive further includes at least one of sulfonyl lactones, cyclic carbonates, phosphates, borates, and nitrile compounds;

[0025] Based on the total mass of the non-aqueous electrolyte as 100%, the amount of the additive added is 0.01% to 30%.

[0026] The sulfonyl lactones are selected from 1,3-propanesulfonyl lactone, 1,4-butanesulfonyl lactone, and 1,3-propenesulfonyl lactone. At least one of them;

[0027] The cyclic carbonate compounds are selected from vinylene carbonate, ethylene ethylene carbonate, methylene carbonate, fluoroethylene carbonate, trifluoromethyl ethylene carbonate, difluoroethylene carbonate, or other compounds with the following structure.

[0028] At least one of the compounds shown in Formula 2:

[0029]

[0030] In structural formula 2, R 21 R22 R 23 R 24 R 25 R 26 Each is independently selected from one of the following: hydrogen atom, halogen atom, or C1-C5 group;

[0031] The phosphate ester compound is selected from at least one of tris(trimethylsilane) phosphate, tris(trimethylsilane) phosphite, or the compound shown in structural formula 3:

[0032]

[0033] In structural formula 3, R 31 R 32 R 33 Each is independently selected from C1-C5 saturated hydrocarbon groups, unsaturated hydrocarbon groups, halohydrocarbon groups, and -Si(C m H 2m+1 )3, m is a natural number from 1 to 3, and R 31 R 32 R 33 At least one of them is an unsaturated hydrocarbon group;

[0034] The borate ester compound is selected from at least one of tris(trimethylsilane)borate ester and tris(triethylsilane)borate ester;

[0035] The nitrile compound is selected from at least one of butadionitrile, glutaronitrile, ethylene glycol bis(propionitrile) ether, hexanetrionitrile, adiponitrile, heptanonitrile, octadionitrile, nonadionitrile, and sebaconitrile.

[0036] According to the lithium-ion battery provided by the present invention, the compound shown in Formula 1 can decompose on the surface of the positive electrode to form an interface film. This interface film can isolate the positive electrode active material and the non-aqueous electrolyte, thereby reducing the decomposition of the non-aqueous electrolyte on the surface of the positive electrode active material. Furthermore, the inventors have discovered that, when controlling the specific surface area of ​​the positive electrode active material, the quality of the interface film formed on the surface of the positive electrode active material is related to the ratio of the micropore specific surface area to the mesopore specific surface area of ​​the positive electrode active material and the content of the compound shown in Formula 1 in the non-aqueous electrolyte. By selecting a positive electrode active material with a specific range of micropore specific surface area to mesopore specific surface area ratio, and adjusting the content of the compound shown in Formula 1, the desired results can be achieved. The condition 0.5≤(Vr / Vr*) / Wr≤12 can effectively suppress the irreversible change in the valence of manganese ions during battery cycling, thereby reducing the dissolution of manganese ions in the manganese-containing cathode material. It is speculated that this is because, under the ratio range of microporous specific surface area and mesoporous specific surface area and the content of the compound shown in structural formula 1, the interfacial film formed by the compound shown in structural formula 1 has a better coordination effect with the manganese element on the surface of the manganese-containing cathode material. A specific network conductive interface is formed at the interface between the cathode active material and the electrolyte phase, which serves as a special lithium ion transport channel, which is conducive to the desorption and transfer of lithium ions. At the same time, it keeps the coordination between metallic manganese ions and O six-coordinate, maintaining the three-dimensional structure of the cathode active material. Detailed Implementation

[0037] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0038] This invention provides a lithium-ion battery, comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte. The positive electrode includes a positive electrode material layer containing a positive electrode active material, wherein the positive electrode active material includes a manganese-containing positive electrode material, and the specific surface area of ​​the positive electrode active material is 0.5–1.5 m². 2 / g, the non-aqueous electrolyte comprises a non-aqueous organic solvent, additives, and a lithium salt, wherein the additives comprise compounds shown in structural formula 1:

[0039]

[0040] Where n is 0 or 1, and X is selected from... R1 and R2 are each independently selected from H, halogens, and unsubstituted or halogenated C1-C5 hydrocarbon groups. And at least one sulfur atom is present in X, R1, and R2;

[0041] The lithium-ion battery meets the following conditions:

[0042] 0.5≤(Vr / Vr*) / Wr≤12, and 0.4≤Vr / Vr*≤1.5, 0.1≤Wr≤3;

[0043] Where Vr is the specific surface area of ​​the micropores in the positive electrode active material, in m³. 2 / g;

[0044] Vr* represents the mesoporous specific surface area of ​​the positive electrode active material, in m³. 2 / g;

[0045] Wr represents the mass percentage of the compound shown in structural formula 1 in the non-aqueous electrolyte, expressed as %.

[0046] The inventors discovered that, under controlled specific surface area of ​​the positive electrode active material, the quality of the interfacial film formed on the surface of the positive electrode active material is related to the ratio of the micropore specific surface area to the mesopore specific surface area of ​​the positive electrode active material and the content of the compound represented by structural formula 1 in the non-aqueous electrolyte. By selecting a positive electrode active material with a specific range of micropore specific surface area to mesopore specific surface area ratio, and in conjunction with structural formula 1... Adjusting the content of the compound shown to satisfy the condition 0.5≤(Vr / Vr*) / Wr≤12 can effectively suppress the irreversible change in the valence of manganese ions during battery cycling, thereby reducing the dissolution of manganese ions in the manganese-containing cathode material. It is speculated that this is because, under the range of the ratio of microporous specific surface area to mesoporous specific surface area and the content of the compound shown in structural formula 1, the interfacial film formed by the compound shown in structural formula 1 has a better coordination effect with the manganese element on the surface of the manganese-containing cathode material. It forms a specific network conductive interface at the interface between the cathode active material and the electrolyte phase, which serves as a special lithium ion transport channel, which is conducive to the desorption and transfer of lithium ions. At the same time, it maintains the six-coordinate relationship between metallic manganese ions and O, thus maintaining the three-dimensional structure of the cathode active material.

[0047] In a preferred embodiment, the lithium-ion battery satisfies the following conditions:

[0048] 1≤(Vr / Vr*) / Wr≤10.

[0049] By further defining the above relationships, the effects of the microporous specific surface area Vr of the positive electrode active material, the mesoporous specific surface area Vr* of the positive electrode active material, and the mass percentage Wr of the compound shown in structural formula 1 in the non-aqueous electrolyte on the dissolution of manganese ions in the manganese-containing positive electrode material can be comprehensively considered, and a stable interfacial film can be formed on the surface of the manganese-containing positive electrode material. The main functions are: 1. It can reduce the impact of polarization; 2. It acts as a barrier to the dissolution of manganese metal ions in the positive electrode, reducing the dissolution of manganese metal ions in the positive electrode; 3. It strengthens the structure of the positive electrode active material through interfacial synergistic effect, while weakening the interfacial impedance between the positive electrode active material and the non-aqueous electrolyte, so that the lithium battery has good rate performance, high-temperature storage performance and high-temperature cycle performance.

[0050] In the description of this invention, "micropore" refers to a pore with a diameter of less than 2 nm, and "mesopore" refers to a pore with a diameter of 2 nm or greater, preferably a pore with a diameter of 2 to 50 nm.

[0051] The terms “microporous specific surface area”, “mesoporous specific surface area”, and “specific surface area of ​​positive electrode active material” can be measured by the nitrogen adsorption BET specific surface area method.

[0052] In some embodiments, the ratio Vr / Vr* of the microporous specific surface area and the mesoporous specific surface area of ​​the positive electrode active material is 0.4, 0.45, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1 or 1.2.

[0053] In a preferred embodiment, the ratio of the microporous specific surface area to the mesoporous specific surface area of ​​the positive electrode active material, Vr / Vr*, is 0.5 to 1.2.

[0054] The ratio of the micropore specific surface area to the mesopore specific surface area of ​​the positive electrode active material, Vr / Vr*, affects the wetting effect of the non-aqueous electrolyte on the positive electrode material layer and also affects the liquid retention in the positive electrode active material. During the initial formation, the liquid retention in the positive electrode active material is related to the thickness of the formed interface film. If the thickness of the formed interface film is too high, it will block some micropores, reduce the actual contact area between the positive electrode active material and the non-aqueous electrolyte, and affect the lithium ion intercalation / deintercalation between the non-aqueous electrolyte and the positive electrode active material. If the thickness of the formed interface film is too low, it will lead to severe side reactions of the non-aqueous electrolyte on the surface of the positive electrode active material and make it difficult to suppress the dissolution of manganese ions. In the battery system of the present invention, when the ratio of the micropore specific surface area to the mesopore specific surface area of ​​the positive electrode active material, Vr / Vr*, is within the above range, it is beneficial to generate an interface film with appropriate thickness and good ionic conductivity, effectively suppressing the valence change of manganese ions and avoiding the impact on battery impedance.

[0055] In some embodiments, the microporous specific surface area Vr of the positive electrode active material is 0.2–0.7 m². 2 / g.

[0056] In some embodiments, the microporous specific surface area Vr of the positive electrode active material can be 0.2 m². 2 / g, 0.4m 2 / g, 0.5m 2 / g, 0.6m 2 / g, 0.7m 2 / g.

[0057] In some embodiments, the mesoporous specific surface area Vr* of the positive electrode active material is 0.14–1.4 m². 2 / g.

[0058] In some embodiments, the mesoporous specific surface area Vr* of the positive electrode active material can be 0.14 m². 2 / g, 0.16m 2 / g, 0.2m 2 / g, 0.3m 2 / g, 0.4m 2 / g, 0.5m 2 / g, 0.6m 2 / g, 0.7m 2 / g, 0.8m 2 / g, 0.9m 2 / g、 1m 2 / g, 1.1m 2 / g, 1.2m 2 / g, 1.3m 2 / g or 1.4m 2 / g.

[0059] In some embodiments, the mass percentage Wr of the compound represented by structural formula 1 in the non-aqueous electrolyte can be 0.1%, 0.2%, 0.4%, 0.5%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.3%, 1.5%, 1.8%, 2.0%, 2.3%, 2.5%, 2.7%, 2.8%, 2.9%, or 3.0%.

[0060] In a preferred embodiment, the mass percentage Wr of the compound represented by structural formula 1 in the non-aqueous electrolyte is 0.1% to 2%.

[0061] The compound shown in Structural Formula 1, within the aforementioned mass percentage range, can decompose on the surface of manganese-containing cathode materials to form a special interfacial film. This interfacial film, through interfacial synergy with the cathode active material with a specific specific surface area, enhances the stability of the manganese-containing cathode material and strengthens the lithium-ion transport channel. In both high-voltage and high-nickel systems, manganese-containing cathode materials are characterized by the easy dissolution of Mn ions. The compound shown in Structural Formula 1 forms a barrier of metal ions (excluding lithium ions) between the manganese-containing cathode material and the non-aqueous electrolyte, which can complex manganese ions, inhibiting their dissolution from the cathode and deposition on the anode; it also shields the contact with the non-aqueous electrolyte, thereby reducing the occurrence of side reactions and the loss of non-aqueous electrolyte, thus significantly improving the high-temperature cycle performance of the battery. The compound shown in Structural Formula 1 weakens the interfacial impedance between the cathode material and the electrolyte, achieving protection for both the cathode and anode materials. At the same time, it can significantly reduce the gas expansion effect of the battery under high-temperature conditions, thereby improving the high-temperature storage performance and high-temperature cycle performance of the battery.

[0062] In some embodiments, under the condition of 500 cycles at a high temperature of 40–60°C, the valence ratio of metal ions Mn in the positive electrode active material is 0.1 ≤ M 2+* / M 4+* ≤0.4, where M 2+* For Mn 2+ Content, M 4+* For Mn 4+ The content of.

[0063] The valence ratio of metal ions Mn in the positive electrode active material can be obtained by testing the following method:

[0064] X-ray photoelectron spectroscopy (XPS) analysis of the cathode revealed a peak with a peak value of 653.1–653.7 eV, representing Mn. 2+ The corresponding 2p¹ / ² peak, the peak area of ​​which corresponds to Mn 2+ The content, with peak values ​​of 653.8–654.2 eV representing Mn. 4+ The corresponding 2p¹ / ² peak, the peak area of ​​which corresponds to Mn 4+ The content was determined by calculating the valence ratio of metal ions Mn in the positive electrode active material through the ratio of the two peak areas.

[0065] In some embodiments, the compound represented by structural formula 1 includes at least one of the following compounds:

[0066]

[0067]

[0068] It should be noted that the above are only preferred compounds of the present invention and do not represent a limitation on the present invention.

[0069] Those skilled in the art, knowing the structural formula of the compound shown in structural formula 1, can understand the preparation method of the above-mentioned compound based on common knowledge in the field of chemical synthesis. For example, compound 15 can be prepared by the following method:

[0070] Sorbitol, dimethyl carbonate, methanol, potassium hydroxide catalyst, and organic solvents such as DMF were placed in a reaction vessel and reacted under heating conditions for several hours. Then, a certain amount of oxalic acid was added to adjust the pH to neutral. After filtration and recrystallization, intermediate product 1 was obtained. Then, intermediate product 1, carbonate, thionyl chloride, etc. were subjected to esterification reaction under high temperature conditions to obtain intermediate product 2. Then, intermediate product 2 was oxidized with an oxidizing agent such as sodium periodate to obtain compound 15.

[0071] In some embodiments, the lithium-ion battery is a pouch battery or a hard-shell battery.

[0072] In some embodiments, the manganese-containing cathode material is selected from LiNi. x Co y Mn z L (1-x-y-z) At least one of O2, wherein L is Al, Sr, Mg, Ti, Ca, Zr, Zn, Si, Cu, V or Fe, and 0 <x≤1,0 ≤y≤1,0<z≤1,0<x+y+z≤1。

[0073] In some embodiments, the positive electrode material layer further includes a positive electrode binder, which includes at least one of polyvinylidene fluoride, copolymers of polyvinylidene fluoride, polytetrafluoroethylene, copolymers of polyvinylidene fluoride-hexafluoropropylene, copolymers of tetrafluoroethylene-hexafluoropropylene, copolymers of tetrafluoroethylene-perfluoroalkyl vinyl ethers, copolymers of ethylene-tetrafluoroethylene, copolymers of polyvinylidene fluoride-tetrafluoroethylene, copolymers of polyvinylidene fluoride-trifluoroethylene, copolymers of polyvinylidene fluoride-trichloroethylene, copolymers of polyvinylidene fluoride-fluorinated vinylidene, copolymers of polyvinylidene fluoride-hexafluoropropylene-tetrafluoroethylene, thermoplastic polyimide, polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, etc.; acrylic resins; sodium hydroxymethyl cellulose; nitrile rubber, polybutadiene rubber, ethylene-propylene rubber, styrene-butadiene-styrene block copolymers or their hydrides, ethylene-propylene-diene terpolymers, polyvinyl acetate, syndiotactic-1,2-polybutadiene, and ethylene-vinyl acetate.

[0074] In some embodiments, the positive electrode material layer further includes a positive electrode conductive agent, which includes at least one of conductive carbon black, conductive carbon spheres, conductive graphite, conductive carbon fiber, carbon nanotubes, graphene, or reduced graphene oxide.

[0075] In some embodiments, the positive current collector is selected from a metallic material that can conduct electrons. Preferably, the positive current collector includes at least one of Al, Ni, tin, copper, and stainless steel. In a more preferred embodiment, the positive current collector is selected from aluminum foil.

[0076] In some embodiments, the negative electrode includes a negative electrode material layer, and the negative electrode material layer includes a negative electrode active material.

[0077] In a preferred embodiment, the negative electrode active material includes at least one of carbon-based, silicon-based, tin-based, and lithium-based negative electrodes. The carbon-based negative electrode may include graphite, hard carbon, soft carbon, graphene, mesophase carbon microspheres, etc.; the silicon-based negative electrode may include silicon materials, silicon oxides, silicon-carbon composite materials, and silicon alloy materials, etc.; the tin-based negative electrode may include tin, tin-carbon, tin oxide, and tin metal compounds; and the lithium-based negative electrode may include metallic lithium or lithium alloys. Specifically, the lithium alloy may be at least one of lithium-silicon alloys, lithium-sodium alloys, lithium-potassium alloys, lithium-aluminum alloys, lithium-tin alloys, and lithium-indium alloys.

[0078] In some embodiments, the negative electrode material layer further includes a negative electrode binder and a negative electrode conductive agent, and the negative electrode active material, the negative electrode binder and the negative electrode conductive agent are blended to obtain the negative electrode material layer.

[0079] The selectable ranges of the negative electrode adhesive and negative electrode conductive agent are the same as those of the positive electrode adhesive and positive electrode conductive agent, and will not be repeated here.

[0080] In some embodiments, the negative electrode further includes a negative electrode current collector, and the negative electrode material layer is formed on the surface of the negative electrode current collector.

[0081] The negative electrode current collector is selected from a metallic material that can conduct electrons. Preferably, the negative electrode current collector includes at least one of Al, Ni, tin, copper, and stainless steel. In a more preferred embodiment, the negative electrode current collector is selected from copper foil.

[0082] In some embodiments, the lithium salt includes LiPF6, LiBOB, LiDFOB, LiPO2F2, LiBF4, LiSbF6, LiAsF6, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiC(SO2CF3)3, LiN(SO2F)2, LiClO4, LiAlCl4, LiCF3SO3, and Li2B. 10 Cl 10At least one of LiSO3F, LiTOP, LiDODFP, LiOTF, and lower aliphatic carboxylic acid lithium salts.

[0083] In some embodiments, the concentration of the lithium salt in the non-aqueous electrolyte is 0.1 mol / L to 8 mol / L. In a preferred embodiment, the concentration of the lithium salt in the non-aqueous electrolyte is 0.5 mol / L to 2.5 mol / L. Specifically, the concentration of the lithium salt in the non-aqueous electrolyte can be 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, or 2.5 mol / L.

[0084] In some embodiments, the non-aqueous organic solvent includes at least one of ether solvents, nitrile solvents, carbonate solvents, and carboxylic acid ester solvents.

[0085] In some embodiments, the ether solvent includes cyclic ethers or chain ethers, preferably chain ethers with 3 to 10 carbon atoms and cyclic ethers with 3 to 6 carbon atoms. The cyclic ethers may specifically include, but are not limited to, at least one of 1,3-dioxolane (DOL), 1,4-dioxane (DX), crown ethers, tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-CH3-THF), and 2-trifluoromethyltetrahydrofuran (2-CF3-THF). The chain ethers may specifically include, but are not limited to, dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, and diethylene glycol dimethyl ether. Because chain ethers have high solvation ability with lithium ions and can improve ion dissociation, dimethoxymethane, diethoxymethane, and ethoxymethoxymethane, which have low viscosity and can impart high ionic conductivity, are particularly preferred. Ether compounds can be used alone or in any combination and ratio of two or more. The content of ether compounds is not particularly limited and is arbitrary as long as it does not significantly impair the performance of the high-pressure lithium-ion battery of this invention. Typically, the volume ratio is 1% or more, preferably 2% or more, and more preferably 3% or more when the non-aqueous solvent volume ratio is 100%. Furthermore, the volume ratio is typically 30% or less, preferably 25% or less, and more preferably 20% or less. When using two or more ether compounds in combination, the total amount of ether compounds should meet the above-mentioned range. When the content of ether compounds is within the above-mentioned preferred range, it is easy to ensure the improved ionic conductivity resulting from the increased lithium-ion dissociation degree and reduced viscosity of the chain ethers. In addition, when the negative electrode active material is a carbon-based material, the phenomenon of co-intercalation between the chain ethers and lithium ions can be suppressed, thus enabling the input / output characteristics and charge / discharge rate characteristics to reach an appropriate range.

[0086] In some embodiments, the nitrile solvent may be, but is not limited to, at least one of acetonitrile, glutaronitrile, and malononitrile.

[0087] In some embodiments, the carbonate solvent includes cyclic carbonates or chain carbonates. Cyclic carbonates may specifically include, but are not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), γ-butyrolactone (GBL), and butylene carbonate (BC); chain carbonates may specifically include, but are not limited to, at least one of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and dipropyl carbonate (DPC). The content of cyclic carbonates is not particularly limited and is arbitrary within a range that does not significantly impair the performance of the lithium-ion battery of the present invention. However, when using only one type, its content is typically 3% or more, preferably 5% or more, by volume relative to the total amount of solvent in the non-aqueous electrolyte. By setting this range, a decrease in conductivity due to a decrease in the dielectric constant of the non-aqueous electrolyte can be avoided, making it easier to achieve good high-current discharge characteristics, stability relative to the negative electrode, and cycle characteristics of the non-aqueous electrolyte battery. Furthermore, the upper limit is typically 90% or less by volume, preferably 85% or less, and more preferably 80% or less by volume. By setting this range, the oxidation / reduction resistance of the non-aqueous electrolyte can be improved, thereby contributing to enhanced stability during high-temperature storage. The content of the chain carbonate is not particularly limited, but relative to the total amount of solvent in the non-aqueous electrolyte, it is typically 15% or more by volume, preferably 20% or more, and more preferably 25% or more. Furthermore, it is typically 90% or less by volume, preferably 85% or less, and more preferably 80% or less. By keeping the chain carbonate content within the above range, it is easier to achieve an appropriate viscosity for the non-aqueous electrolyte, suppressing the decrease in ionic conductivity, and thus contributing to achieving a favorable range of output characteristics for the non-aqueous electrolyte battery. When using two or more chain carbonates in combination, it is sufficient to ensure that the total amount of chain carbonate meets the above range.

[0088] In some embodiments, fluorine-containing chain carbonates (hereinafter referred to as "fluorinated chain carbonates") are also preferably used. There is no particular limitation on the number of fluorine atoms in a fluorinated chain carbonate as long as it is 1 or more, but it is generally 6 or less, preferably 4 or less. When a fluorinated chain carbonate has multiple fluorine atoms, these fluorine atoms can be bonded to the same carbon atom or to different carbon atoms. Examples of fluorinated chain carbonates include dimethyl fluorinated carbonate derivatives, methyl ethyl fluorinated carbonate derivatives, and diethyl fluorinated carbonate derivatives.

[0089] Carboxylic acid ester solvents include cyclic carboxylic acid esters and / or chain carbonates. Examples of cyclic carboxylic acid esters include at least one of γ-butyrolactone, γ-valerolactone, and δ-valerolactone. Examples of chain carbonates include at least one of methyl acetate (MA), ethyl acetate (EA), propyl acetate (EP), butyl acetate, propyl propionate (PP), and butyl propionate.

[0090] In some embodiments, the sulfone solvent includes cyclic sulfones and chain sulfones. Preferably, in the case of cyclic sulfones, it is typically a compound with 3 to 6 carbon atoms, more preferably 3 to 5 carbon atoms; in the case of chain sulfones, it is typically a compound with 2 to 6 carbon atoms, more preferably 2 to 5 carbon atoms. The content of the sulfone solvent is not particularly limited and is arbitrary within a range that does not significantly impair the performance of the lithium-ion battery of the present invention. Relative to the total amount of solvent in the non-aqueous electrolyte, it is typically 0.3% or more by volume, preferably 0.5% or more by volume, more preferably 1% or more by volume. Furthermore, it is typically 40% or less by volume, preferably 35% or less by volume, more preferably 30% or less by volume. When using two or more sulfone solvents in combination, the total amount of sulfone solvent should satisfy the above range. When the content of the sulfone solvent is within the above range, a non-aqueous electrolyte with excellent high-temperature storage stability is preferred.

[0091] In the preferred embodiment, the non-aqueous organic solvent includes at least one of ethylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, propylene carbonate, butyl acetate, γ-butyrolactone, propyl propionate, ethyl propionate, ethyl butyrate, methyl acetate, ethyl acetate, ethyl fluoroacetate, and fluoroether.

[0092] In a preferred embodiment, the non-aqueous organic solvent is a mixture of cyclic carbonates and chain carbonates.

[0093] In some embodiments, the additive further includes at least one of sulfonyl lactones, cyclic carbonates, phosphates, borates, and nitrile compounds;

[0094] Preferably, the content of the additive is 0.01% to 30% based on the total mass of the non-aqueous electrolyte (100%).

[0095] In some embodiments, the sulfonyl lactone compound is selected from at least one of 1,3-propanesulfonyl lactone, 1,4-butanesulfonyl lactone, and 1,3-propenesulfonyl lactone.

[0096] The cyclic carbonate compounds are selected from vinylene carbonate, ethylene ethylene carbonate, methylene carbonate, fluoroethylene carbonate, trifluoromethyl ethylene carbonate, difluoroethylene carbonate, or other compounds with the following structure.

[0097] At least one of the compounds shown in Formula 2:

[0098]

[0099] In structural formula 2, R 21 R 22 R 23 R 24 R 25 R 26 Each is independently selected from one of the following: hydrogen atom, halogen atom, or C1-C5 group;

[0100] The phosphate ester compound is selected from at least one of tris(trimethylsilane) phosphate, tris(trimethylsilane) phosphite, or the compound shown in structural formula 3:

[0101]

[0102] In structural formula 3, R 31 R 32 R 33 Each is independently selected from C1-C5 saturated hydrocarbon groups, unsaturated hydrocarbon groups, halohydrocarbon groups, and -Si(C m H 2m+1 )3, m is a natural number from 1 to 3, and R 31 R 32 R 33 At least one of them is an unsaturated hydrocarbon group;

[0103] In a preferred embodiment, the phosphate ester compound represented by structural formula 3 may be at least one of the following: triargyl phosphate, diallyl methyl phosphate, diallyl ethyl phosphate, diallyl propyl phosphate, diallyl trifluoromethyl phosphate, diallyl-2,2,2-trifluoroethyl phosphate, diallyl-3,3,3-trifluoropropyl phosphate, diallyl hexafluoroisopropyl phosphate, triallyl phosphate, diallyl methyl phosphate, diallyl ethyl phosphate, diallyl propyl phosphate, diallyl trifluoromethyl phosphate, diallyl-2,2,2-trifluoroethyl phosphate, diallyl-3,3,3-trifluoropropyl phosphate, and diallyl hexafluoroisopropyl phosphate.

[0104] The borate ester compound is selected from at least one of tris(trimethylsilane)borate ester and tris(triethylsilane)borate ester;

[0105] The nitrile compound is selected from at least one of butadionitrile, glutaronitrile, ethylene glycol bis(propionitrile) ether, hexanetrionitrile, adiponitrile, heptanonitrile, octadionitrile, nonadionitrile, and sebaconitrile.

[0106] In other embodiments, the additive may also include other additives that can improve battery performance: for example, additives that improve battery safety performance, such as flame retardant additives like fluorophosphates and cyclophosphonitriles, or overcharge prevention additives like tert-amylbenzene and tert-butylbenzene.

[0107] It should be noted that, unless otherwise specified, the content of any optional substance in the additive in the non-aqueous electrolyte is generally less than 10%, preferably 0.1-5%, and more preferably 0.1% to 2%. Specifically, the content of any optional substance in the additive can be 0.05%, 0.08%, 0.1%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 7.8%, 8%, 8.5%, 9%, 9.5%, or 10%.

[0108] In some embodiments, when the additive is selected from fluoroethylene carbonate, the content of fluoroethylene carbonate is 0.05% to 30% based on 100% of the total mass of the non-aqueous electrolyte.

[0109] In some embodiments, the lithium-ion battery further includes a separator located between the positive electrode and the negative electrode.

[0110] The diaphragm can be a conventional diaphragm, such as a ceramic diaphragm, a polymer diaphragm, a non-woven fabric, or an inorganic-organic composite diaphragm. The polymer diaphragm is selected from one or more of polyolefins, polyamides, polysulfones, polyphosphazenes, polyethersulfones, polyetheretherketones, polyetheramides, and polyacrylonitriles, including but not limited to single-layer PP (polypropylene), single-layer PE (polyethylene), double-layer PP / PE, double-layer PP / PP, and triple-layer PP / PE / PP diaphragms.

[0111] In a preferred embodiment, the diaphragm includes a substrate diaphragm and a surface coating, wherein the surface coating is inorganic particles or an organic gel or a mixture thereof and is coated on at least one side of the substrate diaphragm.

[0112] The present invention will be further illustrated by the following examples.

[0113] The compounds involved in the following examples and comparative examples are shown in the table below:

[0114] Table 1

[0115]

[0116]

[0117] Table 2. Parameter Design for Examples and Comparative Examples

[0118]

[0119]

[0120] Example 1

[0121] This embodiment illustrates the lithium-ion battery and its preparation method disclosed in this invention, and includes the following steps:

[0122] 1) Preparation of electrolyte

[0123] Ethylene carbonate (EC), diethyl carbonate (DEC), and methyl ethyl carbonate (EMC) were mixed in a mass ratio of EC:DEC:EMC = 1:1:1. Then, lithium hexafluorophosphate (LiPF6) was added to a molar concentration of 1 mol / L. Additives were then added and mixed thoroughly. The types and contents of additives are shown in Table 2.

[0124] 2) Preparation of positive electrode sheet

[0125] Polyvinylidene fluoride (PVDF), a positive electrode active material, a conductive agent, and a binder, were mixed in a mass ratio of 93:4:3. The types and specific surface areas of the positive electrode active material, as well as the ratio of microporous to mesoporous specific surface areas, are shown in Table 2. These materials were then dispersed in N-methyl-2-pyrrolidone (NMP) to obtain a positive electrode slurry. The slurry was uniformly coated on both sides of an aluminum foil, and after drying, calendering, and vacuum drying, aluminum leads were welded on using an ultrasonic welder to obtain the positive electrode sheet. The thickness of the electrode sheet was 120-150 μm.

[0126] 3) Preparation of negative electrode sheet

[0127] Artificial graphite, conductive carbon black Super-P, styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC) were mixed in a mass ratio of 94:1:2.5:2.5 and then dispersed in deionized water to obtain a negative electrode slurry. The slurry was coated on both sides of a copper foil, dried, calendered, and vacuum dried, and then nickel leads were welded on using an ultrasonic welder to obtain a negative electrode sheet with a thickness of 120-150 μm.

[0128] 4) Cell fabrication

[0129] A three-layer separator with a thickness of 20 μm is placed between the positive electrode and the negative electrode. Then, the sandwich structure composed of the positive electrode, the negative electrode and the separator is wound up. The wound body is then flattened and placed in an aluminum foil packaging bag. It is then vacuum baked at 75°C for 48 hours to obtain the battery cell to be injected with electrolyte.

[0130] 5) Electrolyte injection and formation of battery cells

[0131] In a glove box with the dew point controlled below -40°C, the electrolyte prepared above was injected into the battery cell, vacuum sealed, and left to stand for 24 hours. Then, the first charge was performed according to the following steps: constant current charging at 0.05C for 180 minutes, constant current charging at 0.1C for 100 minutes, constant current charging at 0.2C to 3.95V, vacuum sealing for the second time, and then further constant current charging at 0.2C to 4.4V. After being left to stand at room temperature for 12 hours, constant current discharging at 0.2C to 3.0V.

[0132] Examples 2-28

[0133] Examples 2-28 illustrate the lithium-ion battery and its preparation method disclosed in this invention, including most of the operational steps in Example 1, with the following differences:

[0134] The additives and their contents, the types of positive electrode active materials, the specific surface area, and the ratio of microporous specific surface area to mesoporous specific surface area of ​​the positive electrode active materials shown in Examples 2-28 of Table 2 were used.

[0135] Comparative Examples 1-8

[0136] Comparative Examples 1-8 are used to compare and illustrate the lithium-ion battery and its preparation method disclosed in this invention, including most of the operation steps in Example 1, with the following differences:

[0137] The additives and their contents, the types of positive electrode active materials, specific surface areas, and the ratio of microporous specific surface area to mesoporous specific surface area of ​​the positive electrode active materials shown in Comparative Examples 1 to 8 in Table 2 were used.

[0138] Performance testing

[0139] The lithium-ion batteries prepared above were subjected to the following performance tests:

[0140] I. High-Temperature Cyclic Performance Test

[0141] The lithium-ion battery was placed in a constant-temperature oven at 45°C and charged at a constant current of 1C to 4.4V (LiNi). 0.5 Co 0.2 Mn 0.3 O2 / artificial graphite battery) or 4.4V (0.4Li2MnO3□0.6LiNiO2 / artificial graphite battery) or 4.8V (LiNi 0.4 Mn 0.6 The O2 / artificial graphite battery is charged at a constant voltage until the current drops to 0.02C, and then discharged at a constant current of 1C to 3.0V. This cycle is repeated, and the discharge capacity of the first and last discharge cycles is recorded.

[0142] Calculate the capacity retention during high-temperature cycling using the following formula:

[0143] Capacity retention rate (%) = (Final discharge capacity / First discharge capacity) × 100%.

[0144] II. High-Temperature Storage Performance Test

[0145] The formed lithium-ion battery was charged to 4.4V (LiNi) at room temperature using a 1C constant current and constant voltage method. 0.5 Co 0.2 Mn 0.3 O2 / artificial graphite battery) or 4.4V (0.4Li2MnO3□0.6LiNiO2 / artificial graphite battery) or 4.8V (LiNi 0.4 Mn 0.6 (O2 / artificial graphite battery) was used to measure the initial discharge capacity and initial battery thickness. After storing the battery at 60℃ for 30 days, it was discharged at 1C to 3V, and the retention capacity, recovery capacity, and post-storage battery thickness were measured. The calculation formula is as follows:

[0146] Battery capacity retention rate (%) = Retained capacity / Initial capacity × 100%;

[0147] Battery capacity recovery rate (%) = Recovered capacity / Initial capacity × 100%;

[0148] Thickness expansion rate (%) = (Battery thickness after storage - Initial battery thickness) / Initial battery thickness × 100%.

[0149] III. Manganese ion leaching detection

[0150] The electrolyte in the cycled battery was collected, and the content (ppm) of Mn element in the electrolyte was detected by inductively coupled plasma optical emission spectrometry (ICP-OES).

[0151] IV. Detection of the valence ratio of metal ions Mn in positive electrode active materials

[0152] After the lithium-ion battery underwent 500 cycles at 40–60°C, it was disassembled, the positive electrode was removed and cleaned, and the positive electrode was tested using X-ray photoelectron spectroscopy (XPS). A peak with a peak value of 653.1–653.7 eV represented Mn. 2+ The corresponding 2p¹ / ² peak, the peak area of ​​which corresponds to Mn 2+ The content, with peak values ​​of 653.8–654.2 eV representing Mn. 4+ The corresponding 2p¹ / ² peak, the peak area of ​​which corresponds to Mn 4+ The content was determined by calculating the valence ratio of metal ions Mn in the positive electrode active material through the ratio of the two peak areas.

[0153] (1) The test results obtained from Examples 1 to 17 and Comparative Examples 1 to 4 are filled in Table 3.

[0154] Table 3

[0155]

[0156] The test results from Examples 1-17 and Comparative Examples 1-4 show that, when the type of positive electrode active material used is the same, the ratio of the microporous specific surface area to the mesoporous specific surface area of ​​the positive electrode active material, Vr / Vr*, and the mass percentage content Wr of the compound shown in structural formula 1 in the non-aqueous electrolyte, satisfy the preset relationship 0.5 ≤ When (Vr / Vr*) / Wr≤12, and 0.4≤Vr / Vr*≤1.5, 0.1≤Wr≤3, lithium-ion batteries exhibit excellent high-temperature cycling and high-temperature storage performance. This is presumably because, within the range of the ratio of microporous surface area to mesoporous surface area and the content of the compound shown in Structural Formula 1, the interfacial film formed by the compound in Structural Formula 1 has a better coordination effect with the manganese element on the surface of the manganese-containing cathode material. This forms a specific network conductive interface at the interface between the cathode active material and the electrolyte phase, serving as a special lithium-ion transport channel, which is beneficial for the desorption and transfer of lithium ions. At the same time, it maintains the six-coordinate relationship between metallic manganese ions and O, preserving the three-dimensional structure of the cathode active material, thereby inhibiting the dissolution of manganese ions in the manganese-containing cathode material and avoiding irreversible changes in the valence of manganese ions during battery cycling.

[0157] The test results from Examples 1 to 17 show that when the ratio of the microporous specific surface area to the mesoporous specific surface area of ​​the positive electrode active material, Vr / Vr*, and the mass percentage content of the compound shown in Structural Formula 1 in the non-aqueous electrolyte, Wr, further satisfies 1≤(Vr / Vr*) / Wr≤10, and 0.5≤Vr / Vr*≤1.2, 0.1≤Wr≤2, the lithium-ion secondary battery exhibits the best high-temperature cycle capacity retention rate, high-temperature storage capacity retention rate, capacity recovery rate, and low thickness expansion rate. It is speculated that the interface film obtained at this time can more effectively reduce the impact of polarization and suppress the dissolution of manganese metal ions from the positive electrode.

[0158] The test results of Comparative Examples 1 to 4 show that when the (Vr / Vr*) / Wr value is greater than or less than the limiting conditions of this battery system, it will lead to a decrease in the stability of the interfacial film formed by the compound shown in Structural Formula 1, which in turn leads to changes in the valence of manganese ions and dissolution, further causing performance degradation of the lithium-ion battery.

[0159] (2) The test results obtained in Examples 4 and 18-22 are filled in Table 4.

[0160] Table 4

[0161]

[0162] The test results of Examples 4 and 18-22 show that, in the lithium-ion battery system provided by the present invention, for different compounds represented by structural formula 1, when the ratio of the microporous specific surface area to the mesoporous specific surface area of ​​the positive electrode active material Vr / Vr*, and the mass percentage content Wr of the compound represented by structural formula 1 in the non-aqueous electrolyte, satisfy the preset relationship 0.5≤(Vr / Vr*) / Wr≤12, they have similar effects and all have a certain improvement effect on the high-temperature cycle performance and high-temperature storage performance of lithium-ion batteries. This indicates that the relationship provided by the present invention is applicable to different compounds represented by structural formula 1.

[0163] (3) The test results obtained in Examples 4 and 23-26 are filled in Table 5.

[0164] Table 5

[0165]

[0166] As can be seen from the test results of Examples 4 and 18-22, in the lithium-ion battery system provided by the present invention, the addition of the above-mentioned additives VC (ethylene carbonate), FEC (fluoroethylene carbonate), PS (1,3-propane sulfonyl lactone), or TMSP (tris(trimethylsilane) phosphate) to the non-aqueous electrolyte can further improve the high-temperature cycle performance and high-temperature storage performance of the battery. It is speculated that this is because the compound shown in structural formula 1 and the above-mentioned additives jointly participate in the formation of the passivation film on the electrode surface, resulting in a passivation film with excellent thermal stability, thereby effectively inhibiting the dissolution of manganese ions, reducing the reaction of the electrolyte on the electrode surface, and improving the electrochemical performance of the battery.

[0167] (4) The test results obtained from Examples 27-28 and Comparative Examples 5-8 are filled in Table 6.

[0168] Table 6

[0169]

[0170] The test results of Examples 27-28 and Comparative Examples 5-8 show that when other manganese-containing materials are used as positive electrode active materials, and the ratio of the micropore specific surface area to the mesopore specific surface area of ​​the positive electrode active material (Vr / Vr*) and the mass percentage content (Wr) of the compound shown in Structural Formula 1 in the non-aqueous electrolyte satisfy the preset relationship 0.5≤(Vr / Vr*) / Wr≤12, 0.4≤Vr / Vr*≤1.5, and 0.1≤Wr≤3, the battery also has good high-temperature cycle performance and high-temperature storage performance, and the dissolution inhibition effect of manganese ions is obvious. This indicates that the relationship provided by the present invention has a universal improvement on the high-temperature performance of lithium-ion batteries using different manganese-containing positive electrode materials.

[0171] The above description is only a 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 within the protection scope of the present invention.

Claims

1. A lithium-ion battery, characterized by, A non-aqueous electrolyte secondary battery includes a positive electrode, a negative electrode, and a non-aqueous electrolyte, the positive electrode includes a positive electrode material layer containing a positive electrode active material, the positive electrode active material includes a manganese-containing positive electrode material, the specific surface area of the positive electrode active material is 0.5-1.5 m 2 / g, the non-aqueous electrolyte includes a non-aqueous organic solvent, an additive, and a lithium salt, the additive includes a compound represented by structural formula 1: Structural Formula 1 wherein n is 0 or 1 and X is selected from or R1, R2are each independently selected from H, halogen, unsubstituted or halogen-substituted C1-C5alkyl, , or and at least one of X, R1and R2contains a sulfur atom; The lithium ion battery satisfies the following conditions: 0.5≤(Vr / Vr*) / Wr≤12, and 0.4≤Vr / Vr*≤1.5, 0.1≤Wr≤3; Wherein, Vr / Vr* is the ratio of the micropore specific surface area to the mesopore specific surface area of the positive electrode active material; Wr is the mass percentage content of the compound shown in Structural Formula 1 in the non-aqueous electrolyte, in %.

2. The lithium-ion battery of claim 1, wherein, The lithium ion battery satisfies the following conditions: 1≤(Vr / Vr*) / Wr≤10.

3. The lithium-ion battery of claim 1, wherein, The ratio Vr / Vr* of the micropore specific surface area to the mesopore specific surface area of the positive electrode active material is 0.5-1.

2.

4. The lithium-ion battery of claim 1, wherein, The micropore specific surface area Vr of the positive electrode active material is 0.2 to 0.7 m 2 / g.

5. The lithium-ion battery of claim 1, wherein, The mesopore specific surface area Vr* of the positive electrode active material is 0.14 to 1.4 m 2 / g.

6. The lithium-ion battery of claim 1, wherein, The mass percentage content Wr of the compound shown in Structural Formula 1 in the non-aqueous electrolyte is 0.1%-2%.

7. The lithium-ion battery of claim 1, wherein, The ratio of valence states of metal ions Mn in the positive electrode active material is 0.1≤M 2+* / M 4+* ≤0.4, wherein M 2+* is the content of Mn 2+ , and M 4+* is the content of Mn 4+ .

8. The lithium-ion battery of claim 1, wherein, The compound shown in Structural Formula 1 includes at least one of the following compounds: Compound 1 Compound 2 Compound 3 Compound 4 Compound 5 Compound 6 Compound 7 Compound 8 Compound 9 Compound 10 Compound 11 Compound 12 Compound 13 Compound 14 Compound 15 Compound 16 Compound 17 Compound 18 Compound 19 Compound 20 Compound 21 Compound 22 Compound 23 Compound 24.

9. The lithium-ion battery of claim 1, wherein, The manganese-containing cathode material is selected from LiNi x Co y Mn z L (1-x-y-z) O2, wherein L is Al, Sr, Mg, Ti, Ca, Zr, Zn, Si, Cu, V, or Fe, 0 < x ≤ 1, 0 ≤ y ≤ 1, 0 < z ≤ 1, 0 < x + y + z ≤ 1.

10. The lithium-ion battery of claim 1, wherein, The additive further includes at least one of a sulfonic acid lactone compound, a cyclic carbonate compound, a phosphate compound, a borate compound, and a nitrile compound; The additive is added in an amount of 0.01%-30% based on the total mass of the non-aqueous electrolyte being 100%.

11. The lithium-ion battery of claim 10, wherein, the sulfolane compound is selected from at least one of 1,3-propane sulfolane, 1,4-butane sulfolane, 1,3-propene sulfolane, 1,4-butene sulfolane, 1,3-propane sulfone, 1,4-butane sulfone, 1,3-propene sulfone, The cyclic carbonate compound is selected from at least one of vinylene carbonate, vinyl ethylene carbonate, methylene vinyl carbonate, fluoro vinyl carbonate, trifluoromethyl vinyl carbonate, difluoro vinyl carbonate, or a compound shown in Structural Formula 2: Structural Formula 2 In the structural formula 2, R 21 , R 22 , R 23 , R 24 , R 25 , R 26 each is independently selected from a hydrogen atom, a halogen atom, one of C1-C5 groups; The phosphate compound is selected from at least one of tris(trimethylsilyl) phosphate, tris(trimethylsilyl) phosphite, or a compound shown in Structural Formula 3: Structural Formula 3 R 31 , R 32 , R 33 are each independently selected from the group consisting of C1-C5 saturated hydrocarbon group, unsaturated hydrocarbon group, halogenated hydrocarbon group, -Si(C m H 2m+1 )3, m is a natural number from 1 to 3, and R 31 , R 32 , R 33 at least one of which is an unsaturated hydrocarbon group; The borate compound is selected from at least one of tris(trimethylsilyl) borate and tris(triethylsilyl) borate; The nitrile compound is selected from at least one of butanedinitrile, pentanedinitrile, ethylene glycol bis(propionitrile) ether, hexanetristitnitrile, hexanedinitrile, heptanedinitrile, octanedinitrile, nonanedinitrile, decanedinitrile.

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