Electrolyte additive, electrolyte and lithium ion battery

Abstract

In order to overcome the problem of poor cycle performance of lithium-ion batteries under high-voltage conditions in the prior art, the present invention provides an electrolyte additive, an electrolyte, and a lithium-ion battery; the electrolyte additive is selected from compound A shown in the following structure: In the electrolyte additive provided by the present invention, the imidazole group in compound A has strong water and acid removal performance, forming N + ions and form ion pairs with anions. At the same time, it can also complex transition metal ions to avoid HF damage to SEI and metal ion catalysis of the electrolyte system. In addition, the active groups in the imidazole ring derivatives can form SEI films at the positive and negative electrodes, improving the uniformity and conductivity of the SEI films. In addition, the conjugated structure of the SO2-N-SO2 group makes the anions have negative charge dispersion and good structural flexibility, which effectively alleviates the SEI film breakage caused by volume expansion of negative electrode materials such as silicon-carbon and silicon-oxygen, and can improve the cycle performance of batteries with silicon negative electrode materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium ion batteries, and in particular relates to an electrolyte additive, an electrolyte and a lithium ion battery. Background Art

[0002] Lithium-ion batteries are widely used in consumer electronics and power batteries due to their high specific energy, fast charge and discharge capabilities, and low self-discharge. As the operating conditions of electronic products and power batteries become increasingly complex, the requirements for lithium-ion batteries are also increasing, especially in terms of battery capacity and lifespan.

[0003] Lithium-ion secondary batteries typically use a mixed solution of cyclic and linear carbonates as the electrolyte solvent. During battery cycling and storage, the solvent undergoes irreversible redox reactions with the active surfaces of the electrode materials, leading to a decrease in battery performance. Therefore, functional additives are typically added to the electrolyte to form a protective film on the electrode surface, preventing the solvent-electrode reaction and improving cycling performance.

[0004] There are many types of electrolyte additives commonly used in the existing technology, including vinylene carbonate (VC), 1,3-propane sultone (PS), etc., which can form a protective film on the electrode surface. However, the stability of these protective films is insufficient. Especially during high-current charge and discharge cycles and high-temperature storage, some components of the protective film will decompose and lose their protective effect. The solvent will react with the electrode and be consumed, resulting in poor cycle performance of lithium-ion batteries at high voltages and a decrease in the overall electrical performance of lithium-ion batteries. Summary of the Invention

[0005] Aiming at the problem in the prior art that the cycle performance of lithium-ion batteries deteriorates under high-voltage conditions, an electrolyte additive, an electrolyte and a lithium-ion battery are provided.

[0006] The technical solutions adopted by the present invention to solve the above technical problems are as follows:

[0007] In one aspect, the present invention provides an electrolyte additive selected from compound A shown in the following structure;

[0008]

[0009] In one aspect, the present invention provides an electrolyte solution comprising an organic solvent, an electrolyte salt and the electrolyte solution additive.

[0010] Optionally, based on the total mass of the electrolyte being 100%, the mass percentage of the compound A is 0.01% to 8%.

[0011] Optionally, the electrolyte salt is a lithium salt, and the concentration of the lithium salt in the electrolyte is 0.5M to 2M.

[0012] Optionally, the additive further includes an auxiliary additive, and the mass percentage of the auxiliary additive is 0.1% to 10% based on the total mass of the electrolyte as 100%;

[0013] The auxiliary additive includes one or more of vinylene carbonate, vinyl ethylene carbonate, methylene ethylene carbonate, fluoroethylene carbonate and bisfluoroethylene carbonate.

[0014] In another aspect, the present invention provides a lithium-ion battery comprising a positive electrode, a negative electrode and the electrolyte.

[0015] Optionally, the positive electrode includes a positive electrode material layer, the positive electrode material layer includes a lithium supplement additive, and the lithium supplement additive includes Li x M y O z , where 1≤x≤6, 1≤y≤6, 2≤z≤12, and M includes one or more of Ni, Co, Fe, Cu, Al, Mn, Ti, P, Si, and C.

[0016] Optionally, the mass ratio of the lithium supplement additive in the positive electrode material layer is 0.01% to 5%.

[0017] Optionally, the lithium supplement additive is selected from Li2NiO2.

[0018] Optionally, the positive electrode material layer further includes a positive electrode active material, and the mass ratio of the positive electrode active material in the positive electrode material layer is 80% to 99%.

[0019] The electrolyte additive provided by the present application includes compound A. The imidazole group in compound A has strong water and acid removal performance, forming N + ions and form ion pairs with anions. At the same time, it can also complex transition metal ions to avoid HF's destruction of SEI and the catalysis of metal ions on the electrolyte system. In addition, the active groups in the imidazole ring derivatives can form SEI films at the positive and negative electrodes, improving the uniformity and conductivity of the SEI films. In addition, the conjugated structure of the SO2-N-SO2 group makes the anions have negative charge dispersion and good structural flexibility, which effectively alleviates the SEI film breakage caused by the volume expansion of negative electrode materials such as silicon-carbon and silicon-oxygen, and can improve the cycle performance of batteries with silicon negative electrode materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 1 is a DQ / DV curve diagram of the electrolyte additive provided by Example 1 and Comparative Example 1 of the present invention (A is Comparative Example 1; B is Example 1). DETAILED DESCRIPTION

[0021] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the conductive agent embodiment. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0022] The present invention provides an electrolyte additive selected from compound A shown in the following structure:

[0023]

[0024] It's important to note that lithium-ion secondary batteries typically use a mixed solution of cyclic and linear carbonates as the electrolyte solvent. During battery cycling and storage, the solvent can undergo irreversible redox reactions with the active surfaces of the electrode materials, leading to a decrease in battery performance. Therefore, functional additives are typically added to the electrolyte to form a protective film on the electrode surface, preventing the solvent-electrode reaction and improving cycling performance.

[0025] There are many types of electrolyte additives commonly used in the existing technology, including vinylene carbonate (VC), 1,3-propane sultone (PS), etc., which can form a protective film on the electrode surface. However, the stability of these protective films is insufficient. Especially during high-current charge and discharge cycles and high-temperature storage, some components of the protective film will decompose and lose their protective effect. The solvent will react with the electrode and be consumed, resulting in poor cycle performance of lithium-ion batteries at high voltages and a decrease in the overall electrical performance of lithium-ion batteries.

[0026] The electrolyte additive provided by the present application includes compound A. The imidazole group in compound A has strong water and acid removal performance, forming N + ions and form ion pairs with anions. At the same time, it can also complex transition metal ions to avoid the damage of HF produced by the decomposition of lithium salts to SEI and the catalysis of metal ions on the electrolyte system. In addition, the active groups in the imidazole ring derivatives can form SEI films at the positive and negative electrodes, thereby improving the uniformity and conductivity of the SEI films. In addition, the conjugated structure of the SO2-N-SO2 group makes the anions have negative charge dispersion and good structural flexibility, which can effectively alleviate the SEI film breakage caused by the volume expansion of negative electrode materials such as silicon-carbon and silicon-oxygen, and can improve the cycle performance of batteries with silicon negative electrode materials.

[0027] Specifically, the synthetic route of compound A is as follows:

[0028]

[0029] Specifically, imidazole solution and triethylamine were added to a dichloromethane solution, stirred evenly, 1 mol of acyl chloride was added dropwise, and the mixture was reacted at 60° C. for 2 h to obtain compound a.

[0030] Compound a and allyl alcohol were added to a dichloromethane solvent, triethylamine was added as a catalyst, and the mixture was stirred evenly. A nucleophilic substitution reaction occurred at 60° C. to obtain compound b.

[0031] Compound b and triethylamine (catalyst) were added to dichloromethane solvent, and sulfonyl chloride was added dropwise. The mixture was stirred evenly and reacted at 60° C. to obtain compound c.

[0032] Compound c was added to dichloromethane solvent, mixed evenly, and then catalyst triethylamine was added, stirred evenly, and reacted at 60° C. to obtain compound d.

[0033] R1K was added to the solution of compound d, stirred evenly, and reacted in an ice-water bath for several hours. The reaction product, compound e, was collected, and then lithium hydroxide was added to obtain compound A.

[0034] Specifically, the compound A is in the form of a white powder, slightly soluble in water at 25°C, and has a density of 1.172 g / cm 3 .

[0035] In another embodiment of the present invention, an electrolyte is provided, comprising an organic solvent, an electrolyte salt, and an additive, wherein the additive comprises the electrolyte additive described in the present application.

[0036] Specifically, the organic solvent includes at least one of an ether solvent, a nitrile solvent, a carbonate solvent, and a carboxylate solvent; the organic solvent is selected from one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl formate, ethyl formate, ethyl propionate, propyl propionate, methyl butyrate, and tetrahydrofuran;

[0037] In one embodiment, based on the total mass of the electrolyte being 100%, the mass percentage of the compound A is 0.01% to 8%.

[0038] Specifically, the mass percentage of the compound A in the electrolyte can be 0.01%, 0.05%, 0.1%, 2%, 3%, 5%, 6% or 8%; preferably, the mass percentage of the compound A in the electrolyte is 0.05% to 5%, and the mass percentage of the compound A in the electrolyte can be 0.05%, 0.1%, 2%, 3% or 5%.

[0039] In one embodiment, the electrolyte salt is a lithium salt, and the concentration of the lithium salt in the electrolyte is 0.5M to 2M.

[0040] Specifically, when the lithium salt concentration is too low, the conductivity of the electrolyte will also decrease, thereby affecting the rate and cycle performance of the entire battery system. When the lithium salt concentration is too high, the viscosity of the electrolyte is too high, which is also not conducive to improving the rate of the battery system. In a preferred embodiment, the lithium salt concentration is 0.9M~1.3M.

[0041] Specifically, the lithium salt is selected from one or more of an organic electrolyte salt and an inorganic electrolyte salt; the inorganic lithium salt includes but is not limited to LiPF6, LiBF4, LiSbF6, LiAsF6, LiTaF6, LiAlCl4, Li2B 10 Cl 10 、Li2B 10 F 10 , LiClO4, LiCF3SO3, chelated orthoborate and chelated orthophosphate lithium salts; organic lithium salts include but are not limited to lithium bis(oxalatoborate) [LiB(C2O4)2], lithium bis(malonate) borate [LiB(O2CCH2CO2)2], lithium bis(difluoromalonate) borate [LiB(O2CCF2CO2)2], lithium (malonate oxalate) borate [LiB(C2O4)(O2CCH2CO2)], lithium (difluoromalonate oxalate) borate [LiB(C2O4)(O2CCH2CO2)], lithium (difluoromalonate oxalate) borate [LiB(C2O4) 4) (O2CCF2CO2)], lithium trioxalatophosphate [LiP(C2O4)3], and lithium tris(difluoromalonate)phosphate [LiP(O2CCF2CO2)3].

[0042] In other embodiments, the lithium salt is selected from fluorine-containing lithium salts, including but not limited to hexafluorophosphate, hexafluoroarsenate, perchlorate, trifluorosulfonyl lithium, difluoro(trifluoromethylsulfonyl)imide lithium, bis(fluorosulfonyl)imide lithium, and tris(trifluoromethylsulfonyl)methyl lithium.

[0043] In one embodiment, the additive further includes an auxiliary additive, and the mass percentage of the auxiliary additive is 0.1% to 10% based on the total mass of the electrolyte being 100%;

[0044] The electrolyte auxiliary additive is an indispensable component of lithium battery electrolyte. The auxiliary additive improves the electrochemical performance of the battery and extends the service life of the battery. Specifically, the auxiliary additive forms a protective film on the electrode surface, which can effectively prevent direct contact between the electrode material and the electrolyte, reduce the occurrence of side reactions, and thus improve the stability and safety of the battery.

[0045] The auxiliary additives include but are not limited to vinylene carbonate and its derivatives, ethylene carbonate derivatives having non-conjugated unsaturated bonds in their side chains, cyclic carbonates substituted by halogens, and salts of chelated orthoborates and chelated orthophosphates. Specifically, the auxiliary additives include one or more of vinylene carbonate, vinyl ethylene carbonate, methylene carbonate, fluoroethylene carbonate, and difluoroethylene carbonate. The addition of the auxiliary additives promotes the formation of the SEI film.

[0046] In another embodiment of the present invention, a lithium-ion battery is provided, comprising a positive electrode, a negative electrode, and the above-mentioned electrolyte.

[0047] The lithium-ion battery further includes a negative electrode and a separator. The separator is placed between the positive electrode and the negative electrode. The lithium-ion battery is prepared by a winding process / lamination process.

[0048] The negative electrode includes a negative electrode material layer, which includes a negative electrode active material, a negative electrode binder and a negative electrode conductor. The negative electrode active material includes at least one of a carbon-based negative electrode, a silicon-based negative electrode, a tin-based negative electrode and a lithium negative electrode.

[0049] The electrolyte includes the electrolyte additive described in the present application. The electrolyte additive provided in the present application includes compound A. The imidazole group in compound A has strong water and acid removal properties, forms N+ ions, and forms ion pairs with anions. At the same time, it can also complex transition metal ions to avoid HF damage to SEI and metal ion catalysis of the electrolyte system. In addition, the active groups in the imidazole ring derivatives can form SEI films at the positive and negative electrodes, thereby improving the uniformity and conductivity of the SEI film.

[0050] In one embodiment, the positive electrode includes a positive electrode material layer, the positive electrode material layer includes a lithium supplement additive, and the lithium supplement additive includes Li x M y O z , where 1≤x≤6, 1≤y≤6, 2≤z≤12, and M includes one or more of Ni, Co, Fe, Cu, Al, Mn, Ti, P, Si, and C.

[0051] Li is added to the positive electrode material layer x M y O z It can provide lithium source during the first charge to compensate for the lithium consumed by the SEI film and improve the first coulomb efficiency. It is especially suitable for negative electrode materials with low first coulomb efficiency such as silicon carbon and silicon oxygen. x M y O z As the amount of added increases, the initial efficiency of the battery increases, but Li x M y Oz The structure of positive electrode lithium supplement additives such as (Li2NiO2) is unstable after delithiation, and it is easy to react with the electrolyte at high potential, causing the electrode interface impedance to increase and deteriorate the battery performance. At this time, the electrolyte additive (compound A) is added to the electrolyte of the lithium ion battery including the above additives. The electrolyte additive has strong dehydration and deacidification performance to form N + ions, and form ion pairs with anions, and at the same time can complex transition metal ions, avoid HF damage to SEI and metal ion catalysis of the electrolyte system. The active groups in the imidazole ring derivatives can form SEI films at the positive and negative electrodes, improve the uniformity and conductivity of the SEI film, and alleviate the side reactions of the positive electrode lithium supplement additive and the electrolyte under high voltage. In addition, the conjugated structure of the SO2-N-SO2 group makes the anion have negative charge dispersion and good structural flexibility, which effectively alleviates the SEI film breakage caused by volume expansion of negative electrode materials such as silicon carbon and silicon oxygen, thereby improving the cycle performance of silicon negative electrode material batteries; in summary, the electrolyte additive and the lithium supplement additive in the lithium ion battery provided by the present application are used simultaneously, which can effectively make up for the defect of structural instability of the lithium supplement additive at high potential after delithiation, and jointly promote the formation of a more flexible and more stable SEI film at the negative electrode interface, while effectively improving the first effect of the battery, and improving the battery cycle performance and high voltage performance.

[0052] In one embodiment, the mass ratio of the lithium supplement additive in the positive electrode material layer is 0.01% to 5%.

[0053] Specifically, the mass ratio of the lithium supplement additive described in the present application in the positive electrode material layer can be 0.01%, 0.05%, 0.1%, 0.5%, 1%, 2%, 3%, 4% or 5%.

[0054] In one embodiment, the lithium supplement additive is selected from Li2NiO2.

[0055] Specifically, adding the lithium supplement additive Li2NiO2 to the positive electrode material layer can provide a lithium source during the first charge of the battery, compensate for the lithium consumed by the SEI film, improve the initial coulombic efficiency, and x M y O z As the amount of addition increases, the initial efficiency of the battery also improves.

[0056] In one embodiment, the positive electrode material layer further includes a positive electrode active material, and the mass ratio of the positive electrode active material in the positive electrode material layer is 80% to 99%.

[0057] The positive electrode active material in the positive electrode material layer is a key component of the lithium-ion battery and directly affects the performance of the battery. Specifically, the positive electrode active material is the component in the lithium battery responsible for providing lithium ions, and realizes energy storage and release through the insertion and deinsertion of lithium ions during the charge and discharge process. There is no special restriction on the type and content of the positive electrode active material, and it can be selected according to actual needs, as long as the positive electrode active material can reversibly insert / deinserte lithium ions.

[0058] In a preferred embodiment, the positive electrode active material may be, but is not limited to, lithium iron phosphate, lithium manganese iron phosphate, lithium cobalt oxide, and ternary LiNi a Co b Mn c At least one of the O2 materials (where a+b+c=1, a≥b).

[0059] The present invention is further described below with reference to the following examples.

[0060] The types and contents of the lithium supplement additives and compound A in the following examples and comparative examples are shown in Table 1.

[0061] Table 1

[0062]

[0063]

[0064] Example 1

[0065] This embodiment is used to illustrate an electrolyte additive, electrolyte, and lithium-ion battery disclosed in the present invention, and includes the following steps:

[0066] Preparation of electrolyte: EC (ethylene carbonate), DEC (diethyl carbonate), and PP (propyl propionate) were mixed in a mass ratio of 1:1:1 as an organic solvent, compound A was added to the organic solvent in a mass percentage as shown in Example 1 in Table 1, and after mixing evenly, LiPF6 was added to obtain an electrolyte with a LiPF6 concentration of 1.15 mol / L.

[0067] Preparation of the positive electrode: The positive electrode active material lithium cobalt oxide (LiCoO2), the conductive agent CNT (carbon nanotube), and the binder PVDF (polyvinylidene fluoride) are mixed in a mass ratio of 95:1.5:1.5, and the total amount of the positive electrode active material is 97%; the mixture is fully stirred and mixed in N-methylpyrrolidone solvent to form a uniform positive electrode slurry, and the slurry is coated on the positive electrode current collector aluminum foil, dried, and cold pressed to obtain the positive electrode.

[0068] Preparation of the negative electrode: The negative electrode active material artificial graphite, the conductive agent acetylene black, the binder styrene-butadiene rubber, and the thickener sodium carboxymethyl cellulose were fully stirred and mixed in a deionized water solvent in a mass ratio of 96:1.2:1.5:1.3 to form a uniform negative electrode slurry, and the slurry was coated on the negative electrode current collector copper foil, dried, and cold pressed to obtain the negative electrode.

[0069] Preparation of lithium-ion batteries: Using PE porous polymer film as the separator, stack the positive electrode, separator and negative electrode in order, with the separator placed between the positive and negative electrodes, then wind the electrode and separator to obtain a roll core, place the roll core in an aluminum-plastic film bag that has been punched and formed, and inject the above-prepared electrolyte into the baked and dried battery cells. After vacuum packaging, standing, formation and other processes, a lithium-ion battery is obtained.

[0070] Examples 2 to 4

[0071] Examples 2 to 4 are used to illustrate an electrolyte additive, electrolyte, and lithium-ion battery disclosed in the present invention, and include most of the operations in Example 1, except that:

[0072] The content of compound A was added according to the content of Examples 2 to 4 in Table 1.

[0073] Examples 5 to 15

[0074] Examples 5 to 15 are used to illustrate an electrolyte additive, electrolyte, and lithium-ion battery disclosed in the present invention, and include most of the operations in Example 1, except that:

[0075] The lithium supplement additive and its content as well as compound A and its content were added according to Examples 5 to 15 described in Table 1.

[0076] Comparative Examples 1-2

[0077] Comparative Examples 1 and 2 are used to compare and illustrate an electrolyte additive, electrolyte, and lithium-ion battery disclosed in the present invention, including most of the operations in Example 1, except that:

[0078] In Comparative Example 1, no lithium supplement additive and compound A were added.

[0079] The added substances and their contents were added according to Comparative Examples 1 and 2 shown in Table 1.

[0080] Performance Testing

[0081] The following performance tests were performed on Examples 1 to 15 and Comparative Examples 1 to 2 prepared above:

[0082] First battery efficiency test

[0083] After the battery is filled with electrolyte and allowed to rest for a period of time, it is charged at 25±2°C. First, charge at a current of 0.02C for 2 hours. Then, charge at a current of 0.1C for 5 hours. Finally, charge at a constant current and constant voltage of 0.5C to 4.45V with a cutoff current of 0.02C. Discharge at a current of 0.2C until the cutoff voltage reaches 3.0V. Final initial efficiency = discharge capacity / (constant current capacity + constant voltage capacity).

[0084] 45℃ cycle test

[0085] The test method is as follows: In a constant temperature chamber at 45±2°C, charge the lithium-ion battery at a constant current and constant voltage of 1C to 4.45V, then set the cutoff current at 0.05C, then discharge it at 1C to 3V. Repeat these charge and discharge conditions multiple times. Calculate the capacity retention after 600 cycles, with three batteries per group. Record the average value.

[0086] Capacity retention rate (%) = 600 cycle discharge capacity (mAh) / third cycle discharge capacity (mAh) * 100%

[0087] Internal resistance increase rate (%) = internal resistance of the battery cell after 600 cycles / internal resistance of the battery cell before cycle * 100% - 1.

[0088] DQ / DV test was performed on Example 1 and Comparative Example 1, and the results were Figure 1 ;

[0089] Depend on Figure 1 It can be clearly seen from the dQ-dV curve that Example 1 with the addition of Compound A has a significant reduction peak at around 3.05V. It is preliminarily judged that Example 1 undergoes a reduction reaction at around 3.05V, that is, it is further believed that Compound A can participate in the negative electrode SEI film formation reaction, improve the uniformity and conductivity of the SEI film, and thus improve the cycle performance of the battery with silicon negative electrode material.

[0090] The test results are entered in Table 2.

[0091] Table 2

[0092]

[0093] From the test results in Table 2, it can be seen that compared with Comparative Example 1, Example 1 has a slightly higher first efficiency and cycle capacity retention rate than Comparative Example 1. This is because Compound A is added in Example 1, thereby improving the first efficiency and cycle performance of the battery. Since the content of Compound A in the embodiment is only 0.01%, the first efficiency and cycle performance are not significantly improved. Compared with Comparative Example 1, after Comparative Example 2 adds 1% of the lithium supplement additive Li2NiO2, the first efficiency of the battery is improved, the cycle performance is slightly improved, and the internal resistance increase rate is deteriorated. This is because the positive electrode lithium supplement additive is unstable at high potential and is prone to side reactions with the electrolyte, increasing the electrode interface impedance and deteriorating. Compared with Examples 5 to 8, Examples 1 to 4 have better first efficiency and cycle performance than Examples 1 to 4. This is because Examples 5 to 8 simultaneously add the lithium supplement additive Li2NiO2 and Compound A, which can effectively make up for the defect of the lithium supplement additive being structurally unstable at high potential after delithiation. The two synergistically promote the formation of a more flexible and structurally stable SEI film at the negative electrode interface, thereby improving the battery cycle performance and improving the battery performance. The first efficiency of the battery; from the test results of Examples 5, 9 to 11, it can be seen that as the content of compound A in the electrolyte increases, its cycle performance is improved; the first efficiency of Examples 12 to 13 is lower than that of other examples, because the content of the lithium supplement additive is relatively low; in Examples 14 to 15, due to the low content of compound A, the cycle performance of the lithium ion battery is also relatively poor; In summary, the imidazole group of compound A in the electrolyte additive of the present application has strong water and acid removal performance, forms N+ ions, and forms ion pairs with anions, and can also complex transition Metal ions can avoid the damage of HF to SEI and the catalysis of metal ions on the electrolyte system. In addition, the active groups in the imidazole ring derivatives can form SEI films at the positive and negative electrodes, thereby improving the uniformity and conductivity of the SEI films. In addition, in the lithium-ion battery provided by the present application, when compound A is used together with the lithium replenishing additive, it can effectively make up for the defect of structural instability of the positive electrode lithium replenishing additive at high potential after delithiation, and jointly promote the formation of a more flexible and structurally stable SEI film at the negative electrode interface, while effectively improving the battery's first efficiency, and improving the battery's cycle performance and high-voltage performance.

[0094] 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 in the scope of protection of the present invention.

Claims

1. A lithium-ion battery, characterized in that: The electrolyte comprises an electrolyte and a positive electrode, wherein the electrolyte comprises an electrolyte additive, an organic solvent and an electrolyte salt, and the electrolyte additive is selected from the compound A shown in the following structure: ； The positive electrode includes a positive electrode material layer, the positive electrode material layer includes a lithium supplement additive, and the lithium supplement additive includes Li x M y O z , where 1≤x≤6, 1≤y≤6, 2≤z≤12, and M is Ni.

2. A lithium-ion battery according to claim 1, characterized in that: Based on the total mass of the electrolyte being 100%, the mass percentage of the compound A is 0.01% to 8%.

3. A lithium-ion battery according to claim 1, characterized in that: The electrolyte salt is a lithium salt, and the concentration of the lithium salt in the electrolyte is 0.5M~2M.

4. A lithium-ion battery according to claim 1, characterized in that: The additives also include auxiliary additives, and the mass percentage of the auxiliary additives is 0.1% to 10% based on the total mass of the electrolyte as 100%; The auxiliary additive includes one or more of vinylene carbonate, vinyl ethylene carbonate, methylene ethylene carbonate, fluoroethylene carbonate and bisfluoroethylene carbonate.

5. The lithium-ion battery according to claim 1, wherein: The mass ratio of the lithium supplement additive in the positive electrode material layer is 0.01% to 5%.

6. The lithium-ion battery according to claim 1, characterized in that: The lithium supplement additive is selected from Li2NiO2.

7. The lithium-ion battery according to claim 1, characterized in that: The positive electrode material layer further includes a positive electrode active material, and the mass ratio of the positive electrode active material in the positive electrode material layer is 80% to 99%.

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