Electrolyte additive, electrolyte and lithium ion battery

Abstract

The application relates to the field of batteries, and specifically provides an electrolyte additive, an electrolyte and a lithium ion battery. The electrolyte additive has a -N-Si- structure in the molecule, can react with water and HF in the electrolyte, inhibits the decomposition of PF5, the N atom of the pyridine ring contains a lone pair of electrons, can react with HF, can play an acid-removing role, and protects the SEI film. The electrolyte additive can reduce the water content and the HF content of the electrolyte, form a stable SEI film, can also inhibit the dissolution of transition metal ions, and improves the stability of the battery.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of batteries, and specifically provides an electrolyte additive, an electrolyte and a lithium ion battery. BACKGROUND

[0002] Ternary cathode lithium ion batteries, as an important part of modern battery technology, play a key role in mobile devices, electric vehicles and renewable energy storage. Among them, energy density is an important indicator to measure the performance of the battery, which determines the amount of electrical energy that the battery can store. In the exploration of improving energy density, increasing the nickel content in the cathode material is considered an effective means.

[0003] Nickel plays an important role in ternary cathode materials, it can improve the energy density of the material, thereby increasing the endurance of the battery. However, with the increase of nickel content, a series of challenges have also been brought. In a high-pressure environment, the oxidation ability of the cathode material will significantly increase, which increases the risk of metal ion dissolution during charging and discharging. Once the metal ions are dissolved, they can destroy the layered structure of the cathode, causing the overall structure of the battery to become unstable, and thus affecting the cycle life of the battery.

[0004] In addition, lithium ion batteries are extremely sensitive to water content, which is also an important factor affecting their performance stability. During the manufacturing and use of the battery, if the moisture control is not proper, it can react with lithium hexafluorophosphate in the electrolyte. This reaction will generate harmful substances such as PF5 and HF. Among them, PF5 will also generate HF (hydrofluoric acid) in the process of further decomposition.

[0005] HF can react with the SEI (solid electrolyte interface) film of the battery, causing the structure of the SEI film to be destroyed. The SEI film is an important structure in the battery that protects the electrode and prevents the electrolyte from directly contacting the electrode. Once it is damaged, the internal resistance of the battery will increase significantly, and the kinetic performance will also deteriorate. This will cause the battery to decline in performance prematurely during the cycle, a phenomenon known as "premature cycle diving".

[0006] At the same time, HF will also cause the dissolution of transition metals in the cathode material, further deteriorating the internal resistance and cycle performance of the battery.

[0007] In order to improve the stability of ternary lithium ion batteries, it is necessary to strictly control the water content of the battery. On the one hand, the environmental humidity of the production process is controlled, and the baking efficiency and time of the battery are improved. However, the production of lithium ion batteries involves many processes, and it is difficult to eliminate the influence of water by controlling the environmental humidity alone. On the other hand, a water removal additive is introduced into the electrolyte. Although the existing water removal additive can improve the cycle performance of the lithium iron phosphate material battery by removing water and acid and forming a dense and stable SEI film on the negative electrode surface to a certain extent, it does not provide an effective solution to the key problems such as active oxygen and transition metal ion dissolution that may be faced by the ternary material battery with higher voltage. SUMMARY

[0008] In order to overcome the above-mentioned defects, the present application provides an electrolyte additive, an electrolyte and a lithium ion battery. The electrolyte additive can reduce the water content and HF content of the electrolyte, form a stable SEI film, and inhibit the dissolution of transition metal ions, thereby improving the stability of the battery.

[0009] In a first aspect, the present application provides an electrolyte additive, the structure of which is as follows:

[0010] wherein R1, R2, R3, R4, R5 and R6 are any one of hydrogen atom, alkenyl, alkynyl, substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted aryl, oxygen-containing group, halogen atom and amino group.

[0011] Further, at least one of R1, R2 and R3 is a hydrogen atom.

[0012] Further, R1, R2 and R3 include a group composed of one or more atoms of N, O, S, F, Cl, Br and I.

[0013] Further, the additive is at least one of the following structural formulas,

[0014]

[0015] In a second aspect, the present application provides an electrolyte, which comprises the electrolyte additive of the first aspect.

[0016] Further, the mass fraction of the electrolyte additive in the electrolyte is 0.1% to 5%.

[0017] Further, the electrolyte further comprises a lithium salt and an organic solvent.

[0018] Further, the lithium salt comprises one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(oxalato)borate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium difluorobis(oxalato)phosphate.

[0019] Further, the organic solvent comprises one or more of ethylene carbonate, propylene carbonate, butylene carbonate, gamma-butyrolactone, methyl ethyl carbonate, dimethyl carbonate, diethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, ethyl acetate, methyl acetate, propyl acetate, propyl propionate, methyl acetate, ethyl butyrate.

[0020] Further, the electrolyte further comprises a functional additive.

[0021] Further, the functional additive comprises one or more of vinylene carbonate, fluoroethylene carbonate, vinyl ethylene carbonate, vinyl sulfate, 1,3 propanesultone, lithium difluorophosphate, lithium bis(oxalato)borate, lithium difluoro bis(oxalato)borate.

[0022] In a third aspect, the present application provides a lithium ion battery, wherein the lithium ion battery comprises the electrolyte according to the second aspect.

[0023] Further, the positive electrode material of the lithium ion battery is a nickel-cobalt-manganese ternary material.

[0024] The above one or more technical solutions of the present application have at least one or more of the following beneficial effects:

[0025] In the implementation of the technical solutions of the present application, the electrolyte additive of the present application not only can reduce the water content and HF content in the electrolyte to form a stable SEI film, but also can stabilize the positive electrode CEI film and inhibit the dissolution of transition metal ions.

[0026] After the electrolyte additive of the present application is added to the electrolyte, the stability of the lithium ion battery, especially the ternary lithium ion battery, can be improved. DETAILED DESCRIPTION

[0027] Some embodiments of the present application are described below. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present application, and are not intended to limit the protection scope of the present application.

[0028] The present application provides an electrolyte additive, wherein the structure of the electrolyte additive is:

[0029]

[0030] Wherein, R1, R2, R3, R4, R5 and R6 are any one of hydrogen atom, alkenyl, alkynyl, substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted aryl, oxygen-containing group, halogen atom and amino group.

[0031] The electrolyte additive has a lower lowest unoccupied molecular orbital (LUMO) and a higher highest occupied molecular orbital (HOMO), can preferentially gain or lose electrons to react in the process of the first charge and discharge, generate a more stable interface film, especially for silane compound molecules, the film forming is more uniform, can maintain the stability of the positive electrode structure, and inhibit the dissolution of transition metal ions.

[0032] The additive molecule has -N-Si- structure, can react with water and HF in the electrolyte, and inhibit the decomposition of PF5.

[0033] The electrolyte additive can occur oxidation reaction on the positive electrode surface at a lower voltage, form a dense CEI film, maintain the stability of the positive electrode structure, and inhibit the dissolution of transition metal ions.

[0034] In one embodiment, at least one of R1, R2 and R3 is hydrogen atom. In this way, the N atom of the pyridine ring contains lone pair electrons, can react with HF, and can play an acid-removing role to protect the SEI film.

[0035] In one embodiment, R1, R2 and R3 include a group composed of one or more atoms of N, O, S, F, Cl, Br and I. Since the atoms contain more lone pair electrons, the polarity is stronger, the electron cloud density is larger, and it is easier to react with electron-deficient H + , and the acid-removing effect is stronger.

[0036] In one embodiment, the additive is at least one of the following structural formulae,

[0037]

[0038] The above components can be used alone or in combination.

[0039] The application provides an electrolyte, which comprises the electrolyte additive.

[0040] In one embodiment, the mass fraction of the electrolyte additive in the electrolyte is 0.1% to 5%.

[0041] By adding an appropriate amount of the additive of the application to the existing electrolyte, not only water and acid can be removed, but also the electrochemical performance of the battery can be improved.

[0042] In one embodiment, the electrolyte further comprises a lithium salt and an organic solvent.

[0043] In one embodiment, the lithium salt comprises one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(oxalato)borate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium difluorobis(oxalato)phosphate.

[0044] In one embodiment, the organic solvent comprises one or more of ethylene carbonate, propylene carbonate, butylene carbonate, gamma-butyrolactone, methyl ethyl carbonate, dimethyl carbonate, diethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, ethyl acetate, methyl acetate, propyl acetate, propyl propionate, methyl acetate, ethyl butyrate.

[0045] In one embodiment, the electrolyte further comprises a functional additive.

[0046] The functional additive can be selected as a film-forming additive and / or a safety additive as needed.

[0047] In one embodiment, the functional additive comprises one or more of vinylene carbonate, fluoroethylene carbonate, vinyl ethylene carbonate, vinyl sulfate, 1,3 propyl sulfonic acid lactone, lithium difluorophosphate, lithium bis(oxalato)borate, lithium difluoro bis(oxalato)borate.

[0048] The functional additive can be added or not added in the electrolyte.

[0049] The ratio of the lithium salt, the organic solvent and the functional additive can be selected as appropriate according to actual needs.

[0050] In one embodiment, the organic solvent in the electrolyte comprises ethylene carbonate and methyl ethyl carbonate, wherein the ethylene carbonate and the methyl ethyl carbonate are uniformly mixed in a mass ratio of 3:7.

[0051] The functional additive is selected as vinylene carbonate (VC). As the electrolyte of the lithium ion battery, the vinylene carbonate can improve the high and low temperature performance of the electrolyte, improve the specific capacity and cycle life of the battery, has the effect of overcharge protection, and has good compatibility with the positive electrode without side effects.

[0052] The lithium salt is lithium hexafluorophosphate.

[0053] Vinylene carbonate and LiPF6 are added in the organic solvent to form a mixture, the mass fraction of the vinylene carbonate in the mixture is 3%, and the mass fraction of the LiPF6 is 12.5%.

[0054] The application also provides a lithium ion battery comprising the electrolyte.

[0055] The electrolyte is added with the electrolyte additive of the application.

[0056] The person skilled in the art knows that, in addition to the electrolyte, there are also positive electrodes, negative electrodes and separators in conventional lithium ion batteries.

[0057] The positive electrode material of the lithium ion battery is a nickel-cobalt-manganese ternary material. The nickel-cobalt-manganese ternary material refers to lithium nickel cobalt manganese oxide Li(NiCoMn)O2. The stable valence of nickel in the material is +2, so the Ni 3+ will spontaneously transform into Ni 2+ , and O 2- is released at the same time. The higher the content of nickel in the material, such as NCM811, NCA and the like, the more than 80% of which the proportion of nickel accounts for, the more easily the material reacts with carbon dioxide and water in the air when exposed to the air. Therefore, when the electrolyte additive of the present application is used in a battery with a nickel-cobalt-manganese ternary material as the positive electrode material, the water content and HF content in the electrolyte can be reduced, a stable SEI film can be formed, and the positive CEI film can also be stabilized, the dissolution of transition metal ions can be inhibited, the ternary electrode material can be stabilized, and the stability of the ternary lithium ion battery can be improved.

[0058] The negative electrode material of the lithium ion battery can be selected from graphite, lithium metal or silicon-carbon material.

[0059] The effect of the electrolyte of the present application will be described below in conjunction with examples.

[0060] I. Preparation of electrolyte

[0061] Comparative Example 1

[0062] In an argon-filled glove box (moisture <10 ppm, oxygen <10 ppm), organic solvents ethylene carbonate and methyl ethyl carbonate were mixed uniformly in a mass ratio of 3:7 to form a mixed solution, and vinylene carbonate and LiPF6 were slowly added to the mixed solution, wherein the mass fraction of vinylene carbonate was 3%, and the mass fraction of LiPF6 was 12.5%. After stirring until complete dissolution, a basic electrolyte for lithium ion batteries was obtained.

[0063] Comparative Example 2

[0064] A sulfonic acid pyridine lipid compound with the following structure was added to the basic electrolyte of Comparative Example 1 to obtain the electrolyte of Comparative Example 2, wherein the mass fraction of the sulfonic acid pyridine lipid compound with the following structure in the electrolyte of Comparative Example 2 was 0.5%.

[0065]

[0066] Example 1

[0067] Compound I was added to the basic electrolyte of Comparative Example 1, and the structural formula is as follows:

[0068]

[0069] An electrolyte of Example 2 was obtained in which the mass fraction of compound II in the electrolyte of Example 2 was 0.5%.

[0070] Example 2

[0071] In the base electrolyte of Comparative Example 1, compound II was added, which has the following structure:

[0072]

[0073] An electrolyte of Example 2 was obtained in which the mass fraction of compound II in the electrolyte of Example 2 was 0.5%.

[0074] Example 3

[0075] In the base electrolyte of Comparative Example 1, compound III was added, which has the following structure:

[0076]

[0077] An electrolyte of Example 3 was obtained in which the mass fraction of compound III in the electrolyte of Example 3 was 0.5%.

[0078] Example 4

[0079] In the base electrolyte of Comparative Example 1, compound IV was added, which has the following structure:

[0080]

[0081] An electrolyte of Example 4 was obtained in which the mass fraction of compound IV in the electrolyte of Example 4 was 0.5%.

[0082] Example 5

[0083] In the base electrolyte of Comparative Example 1, compound V was added, which has the following structure:

[0084]

[0085] An electrolyte of Example 5 was obtained in which the mass fraction of compound V in the electrolyte of Example 5 was 0.5%.

[0086] Example 6

[0087] In the base electrolyte of Comparative Example 1, compound VI was added, which has the following structure:

[0088]

[0089] An electrolyte of Example 6 was obtained in which the mass fraction of compound VI in the electrolyte of Example 6 was 0.5%.

[0090] Example 7

[0091] Example 7 electrolyte was prepared by adding compound VI to the base electrolyte of Comparative Example 1, wherein the mass fraction of compound VI in the electrolyte of Example 7 was 0.1%.

[0092] Example 8

[0093] Example 8 electrolyte was prepared by adding compound VI to the base electrolyte of Comparative Example 1, wherein the mass fraction of compound VI in the electrolyte of Example 8 was 0.3%.

[0094] Example 9

[0095] Example 9 electrolyte was prepared by adding compound VI to the base electrolyte of Comparative Example 1, wherein the mass fraction of compound VI in the electrolyte of Example 9 was 0.7%.

[0096] Example 10

[0097] Example 10 electrolyte was prepared by adding compound VI to the base electrolyte of Comparative Example 1, wherein the mass fraction of compound VI in the electrolyte of Example 10 was 1.0%.

[0098] Example 11

[0099] Example 11 electrolyte was prepared by adding compound VI to the base electrolyte of Comparative Example 1, wherein the mass fraction of compound VI in the electrolyte of Example 11 was 5.0%.

[0100] II. Preparation of lithium ion battery

[0101] (1) Preparation of positive electrode sheet: LiNi 0.8 Co 0.1 Mn 0.1 O2 positive electrode active material, polyvinylidene fluoride binder (PVDF), conductive carbon (SP) were mixed in a certain weight ratio, and a proper amount of N-methyl pyrrolidone (NMP) was added to stir for a proper time to form a uniform positive electrode slurry; the positive electrode slurry was uniformly coated on an aluminum foil and dried in a vacuum oven at 100°C, and then rolled and cut to obtain a positive electrode sheet.

[0102] (2) Preparation of negative electrode sheet: artificial graphite, conductive agent carbon black, binder styrene-butadiene rubber (SBR), thickening agent sodium hydroxymethyl cellulose (CMC) were mixed in a certain weight ratio, and a proper amount of deionized water was added to stir for a proper time to form a uniform negative electrode slurry; the negative electrode slurry was uniformly coated on a copper foil and dried in a vacuum oven at 100°C, and then rolled and cut to obtain a negative electrode sheet.

[0103] (3) Battery preparation:

[0104] The prepared positive and negative electrode sheets, polyethylene separator were assembled into soft package battery and baked at 100°C for 48h to ensure the water content of the positive and negative electrode sheets and the separator was below 200ppm. Then the battery was transferred to the glove box for liquid injection, and the electrolyte used was the electrolyte in the above comparative example 1-2 and example 1-11. After the liquid injection, the battery was subjected to the steps of standing, formation, aging, shaping and capacity distribution to obtain a complete lithium ion battery.

[0105] III. Test of electrolyte:

[0106] The electrolyte in the above comparative example 1-2 and example 1-11 was placed in the glove box for storage for 14 days, and the HF content of the electrolyte before and after storage was tested, and the test results were as follows:

[0107] Table 1 Change of HF content in electrolyte before and after storage

[0108] Group HF content before storage / ppm HF content after storage / ppm Comparative Example 1 15.2 21.4 Comparative Example 2 16.4 10.1 Example 1 14.8 9.5 Example 2 14.7 9.8 Example 3 14.8 8.6 Example 4 14.7 8.4 Example 5 15.3 7.9 Example 6 14.9 7.7 Example 7 15.1 9.2 Example 8 15.4 8.5 Example 9 14.8 7.5 Example 10 14.6 7.5 Example 11 15.4 7.3

[0109] HF content is an important indicator of the stability of the electrolyte. The level of HF content not only relates to the capacity and energy density of the battery, but also is closely related to its safety and life. Therefore, the test of the HF content of the electrolyte is of great significance.

[0110] During the storage process, the glove box was used to simulate the storage conditions of the electrolyte in actual application. The glove box has the characteristics of good sealing and stable environment, which can effectively isolate the external air and moisture, so as to ensure that the electrolyte will not be disturbed by external factors during storage.

[0111] Analyzing the experimental data in Table 1, first, compared with the electrolyte in comparative example 1, examples 1 to 11 and comparative example 2, the HF content of the electrolyte after 14 days of storage has a significant downward trend. This significant change shows that after adding the additive to the electrolyte, the content of HF is indeed reduced, that is, the acid removal effect is achieved.

[0112] Further analysis of the data of examples 1 to 6, under the condition of the same content of the additive, the compounds III-IV with substituents on the pyridine ring that meet the priority condition show more excellent acid removal effect, which has obvious advantages compared with compounds I and II.

[0113] And in the experiments of examples 7 to 11, it can be seen that with the gradual increase of the content of the additive, the acid removal effect of the electrolyte is also continuously improved. Especially worth mentioning is that when the content of the additive increases from 0.1% to 0.5%, the improvement of the acid removal effect is particularly significant.

[0114] However, when the additive content is further increased to 5.0%, the improvement of acid removal effect is not obvious. This phenomenon may mean that after reaching a certain additive concentration, further increasing its content will not bring obvious improvement of acid removal effect.

[0115] In summary, adding an appropriate amount of additive to the electrolyte can effectively reduce the HF content during storage, thereby improving the performance of the electrolyte. In the selection of additives, the inventive additive compounds, especially compounds III-IV with substituents on the pyridine ring, perform better. However, although increasing the content can bring better acid removal effect, too high a content may not lead to obvious improvement of the effect.

[0116] IV. Test of lithium ion battery:

[0117] (1) Initial DC resistance (DCR) test:

[0118] The initial DC resistance (DCR) test is one of the key items for evaluating the performance of lithium ion batteries, which helps to understand the resistance characteristics of the battery under certain conditions.

[0119] During the initial DC resistance test, the battery is charged to 50% state of charge, and after the charging is completed, the battery is left for 30 minutes to ensure that the internal battery reaches a stable state. Next, the battery is discharged at a current of 2C (denoted as I) for 30 seconds. During this process, the voltage change of the battery is observed. Before discharging, the initial voltage V1 of the battery is recorded; immediately after discharging, the terminal voltage V2 of the battery is recorded. These two voltage values will be used to calculate the initial DC resistance. The initial DC resistance is calculated by the following formula: DCR = (V1-V2) / I.

[0120] (2) 25℃ cycle test:

[0121] The lithium ion battery is subjected to charge-discharge cycle test at 1C / 1C rate, and the charge-discharge voltage interval is 2.8-4.2V. The cycle capacity retention rate is the last cycle discharge capacity after cycling / first cycle discharge capacity.

[0122] (3) Transition metal leaching test:

[0123] In the research of lithium ion battery negative electrode sheet, inductively coupled plasma optical emission spectrometry (ICP-OES) technology is a commonly used analysis method. ICP-OES technology excites elements in the sample by high temperature, atomizes and emits light of specific wavelength, and by measuring the intensity of these light, the content of elements in the sample can be accurately determined.

[0124] After the lithium ion battery after circulation is disassembled to obtain the negative electrode sheet, a certain amount of negative electrode sheet is taken for inductively coupled plasma optical emission spectrometry (ICP-OES) test. By testing the content of Ni element in the negative electrode sheet, the dissolution of the transition metal in the positive electrode can be understood.

[0125] The test results of the lithium ion batteries made of the electrolytes of Comparative Example 1-2 and Example 1-11 are shown in Table 2.

[0126] Table 2 Electrochemical test results of the batteries corresponding to Comparative Example 1-2 and Example 1-11

[0127]

[0128] Through in-depth analysis of Table 2, it can be seen that, compared with Comparative Example 1, the capacity retention rates of the batteries corresponding to the electrolytes of Comparative Example 2 and Example 1-11 after cycling all show a higher level. The content of Ni element in the negative electrode is lower, and the results show that the additives of the present application and Comparative Example 1 have certain effect on inhibiting the dissolution of transition metal.

[0129] The significant reduction of the content of Ni in the negative electrode sheet of Example 1-11 compared with Comparative Example 2 after cycling. This improvement is achieved on the one hand due to the reduction of the content of HF in the electrolyte. HF, as a strong acid, has strong corrosiveness to metal materials in the battery, so reducing its content can effectively reduce the dissolution of transition metal. On the other hand, this is also closely related to the improvement of the stability of the positive electrode structure. The positive electrode material of the battery corresponding to the electrolyte of Example 1-11 is more stable, and the stability is better, thereby reducing the dissolution of transition metal during cycling.

[0130] Although the sulfonic acid pyridine lipid compound in Comparative Example 2 shows certain effect in inhibiting acid, it is inferior to silane molecules in promoting film uniformity. This leads to its poor effect in inhibiting the dissolution of transition metal, and the cycle stability of the battery is also poor.

[0131] In the design of battery materials, not only the improvement of single function should be concerned, but also the optimization of overall performance should be focused on.

[0132] In addition, from the results of Examples 6-8, it can be seen that when the content of the additive is in the range of 0.1% to 0.5%, the DCR of the battery has been significantly reduced compared with Comparative Example 1 without additive. This shows that the additive plays an active role in the process of forming positive and negative electrodes, which helps to reduce the DCR of the battery, thereby improving the kinetic performance of the battery.

[0133] However, when the additive content continues to increase to a certain extent, the impedance involved in film formation becomes large, and both DCR and capacity retention become small. Thus, in optimizing battery performance, the amount of additive is not the more the better, but a suitable balance point needs to be found to maximize performance.

[0134] The electrolyte additive of the present application has a -N-Si- structure, can react with water and HF in the electrolyte, inhibit the decomposition of PF5, significantly reduce the corrosion of acidic impurities on the electrode material, thereby prolonging the service life of the battery.

[0135] In the electrolyte additive, the more atomic lone pair of electrons, the stronger the deacidification effect.

[0136] The addition amount of the electrolyte additive in the electrolyte is within a certain range, which can play a better effect.

[0137] It should be noted that although the above embodiments describe each step in a specific order, those skilled in the art can understand that in order to achieve the effect of the present application, the different steps do not necessarily have to be executed in such an order, they can be executed simultaneously (in parallel) or in other order, and these changes are within the protection scope of the present application.

[0138] So far, the technical solutions of the present application have been described in combination with preferred embodiments, but those skilled in the art can easily understand that the protection scope of the present application is obviously not limited to these specific embodiments. Those skilled in the art can make equivalent changes or replacements to the related technical features without departing from the principles of the present application, and the technical solutions after these changes or replacements will fall within the protection scope of the present application.

Claims

1. The application of an electrolyte additive in lithium-ion battery electrolytes, characterized in that, The electrolyte additive is at least one of the following structural formulas. 。 2. A lithium-ion battery electrolyte, characterized in that, The lithium-ion battery electrolyte includes an electrolyte additive, which is at least one of the following structural formulas. 。 3. The lithium-ion battery electrolyte according to claim 2, characterized in that, The electrolyte additive has a mass fraction of 0.1% to 5% in the lithium-ion battery electrolyte.

4. The lithium-ion battery electrolyte according to claim 3, characterized in that, The lithium-ion battery electrolyte also includes lithium salt and organic solvent.

5. The lithium-ion battery electrolyte according to claim 4, characterized in that, The lithium salt includes one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(oxalate)borate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, and lithium difluorobis(oxalate)phosphate.

6. The lithium-ion battery electrolyte according to claim 4, characterized in that, The organic solvent includes one or more of the following: ethylene carbonate, propylene carbonate, butene carbonate, γ-butyrolactone, methyl ethyl carbonate, dimethyl carbonate, diethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, ethyl acetate, methyl acetate, propyl acetate, propyl propionate, methyl acetate, and ethyl butyrate.

7. The lithium-ion battery electrolyte according to claim 6, characterized in that, The lithium-ion battery electrolyte further includes: functional additives; the functional additives include one or more of the following: vinylene carbonate, fluoroethylene carbonate, ethylene ethylene carbonate, ethylene sulfate, 1,3-propyl sulfonate lactone, lithium difluorophosphate, lithium dioxalate borate, and lithium difluorooxalate borate.

8. A lithium-ion battery, characterized in that, The lithium-ion battery includes the lithium-ion battery electrolyte according to any one of claims 2-7.

9. The lithium-ion battery according to claim 8, characterized in that, The positive electrode material of the lithium-ion battery is a nickel-cobalt-manganese ternary material.

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