Lithium-ion battery electrolyte and lithium-ion battery and lithium supplement method thereof

Abstract

The application provides a lithium ion battery electrolyte and a lithium ion battery and a lithium supplement method thereof, and particularly relates to the field of secondary batteries. The lithium ion battery electrolyte comprises an organic solvent, a lithium salt and a lithium supplement additive, the lithium salt and the lithium supplement additive are dissolved in the organic solvent, and the lithium supplement additive is selected from a lithium conjugated furan diol compound. When the battery is charged, the lithium conjugated furan diol compound can release lithium ions at the positive electrode, make up for the loss of active lithium at the negative electrode caused by side reactions or irreversibility, realize lithium supplement, and thus prolong the cycle life of the battery.

Description

Technical Field

[0001] This invention relates to the field of secondary battery technology, specifically to a lithium-ion battery electrolyte, a lithium-ion battery, and a method for replenishing lithium. Background Technology

[0002] Commercial lithium-ion batteries are striving for the ultimate in cell cycle life, with energy storage cell technology advancing towards 10,000 cycles and a capacity retention rate of over 80%. From the perspective of improving the chemical system, long cycle performance is closely related to the amount of active lithium remaining after each cycle. In power cells, silicon anode systems are favored due to their high energy density; however, the irreversible capacity loss in the first cycle of silicon-oxygen materials leads to significant active lithium loss, reducing capacity and worsening cycle performance. Therefore, various lithium replenishment technologies have been developed to replenish active lithium during battery formation or cycling, maintaining battery cycle performance and reducing irreversible losses.

[0003] Currently, lithium replenishment technology mainly focuses on positive electrode lithium replenishment and negative electrode lithium replenishment. Positive electrode lithium replenishment involves adding a material with a specific capacity much larger than that of the positive electrode and an extremely large irreversible capacity. In this way, during the first charge cycle, the positive electrode will release more lithium ions than the design limit, and the excess can fill the losses in the film formation reaction. Negative electrode lithium replenishment involves adding a portion of zero-valent lithium to the negative electrode beforehand, which is then re-oxidized into lithium ions during the first discharge cycle and reinserted into the positive electrode.

[0004] In summary, the core of lithium replenishment technology lies in compensating for the mismatch in charge states between the positive and negative electrodes during charging and discharging. Therefore, lithium replenishment technology either contributes substances that can be oxidized and release lithium ions to the positive electrode or contributes zero-valent lithium to the negative electrode. Currently, positive electrode lithium replenishment typically uses Li6CoO4, Li2NiO2, or Li5FeO4, commonly used in lithium iron phosphate energy storage systems. However, a large amount of active oxygen is generated after the first charge cycle. Some of this oxygen is released as oxygen, while the rest reacts with organic components in the electrolyte, damaging the electrolyte's stability and affecting cycle life. Negative electrode lithium replenishment is usually used on silicon anodes, where elemental lithium is incorporated into the silicon-carbon / silicon-oxygen anode through pre-lithiation. However, the anode is sensitive to water and oxygen in the air, making it extremely unstable and posing serious safety risks. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the present invention provides a lithium-ion battery electrolyte, a lithium-ion battery and a lithium replenishment method thereof, which improves the above-mentioned problems by adding lithium-containing additives to the lithium-ion battery electrolyte.

[0006] To achieve the above and other related objectives, the present invention provides a lithium-ion battery electrolyte comprising an organic solvent, a lithium salt, and a lithium-replenishing additive, wherein the lithium salt and the lithium-replenishing additive are dissolved in the organic solvent, and the lithium-replenishing additive releases lithium ions at the positive electrode during battery charging, wherein the lithium-replenishing additive is selected from conjugated furan glycol lithium compounds.

[0007] In one example of the present invention, the conjugated lithium furan glycol compound includes at least one of lithium 2,5-furan glycol and its derivatives, the general structural formula of the lithium 2,5-furan glycol derivatives being shown below:

[0008]

[0009] R1 and R2 are each independently selected from hydrogen atoms, halogen atoms, and carbon atoms. 1-12 Hydrocarbon group or hydrocarbon oxygen substituent, C 1-12 It contains any one of the following: carbonyl group, sulfonic acid group, sulfate ester group, and silyl vinyl substituent.

[0010] In one example of the present invention, the lithium supplementing additive is selected from at least one of the following compounds:

[0011]

[0012]

[0013]

[0014] In one example of the present invention, the amount of the lithium-replenishing additive is calculated according to its lithium-replenishing equivalent, and the lithium-replenishing equivalent of the lithium-ion battery electrolyte is 0.1 to 1 mmol / Ah relative to the battery capacity.

[0015] In one example of the present invention, the lithium salt includes LiPF6, and the concentration of the lithium salt in the lithium-ion battery electrolyte is 0.1 to 2 mol / L.

[0016] In one example of the present invention, the organic solvent includes cyclic carbonates and chain carbonates, wherein the cyclic carbonates include one or both of ethylene carbonate and propylene carbonate, and the chain carbonates include at least one of dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

[0017] In another aspect, the present invention provides a lithium-ion battery, the lithium-ion battery comprising a positive electrode, a negative electrode, a separator and the above-described lithium-ion battery electrolyte.

[0018] The present invention also provides a method for replenishing lithium in a lithium-ion battery, the method comprising injecting the above-mentioned lithium-ion battery electrolyte into the lithium-ion battery and charging the lithium-ion battery to replenish lithium.

[0019] In one example of the present invention, the charging voltage of the lithium-ion battery is 2.8 to 4.2V.

[0020] In one example of the present invention, during the charging process, the lithium replenishing additive in the lithium-ion battery electrolyte undergoes oxidation and lithium loss at the positive electrode of the lithium-ion battery, generating a conjugated carbonyl-olefin-carbonyl structure and releasing lithium ions.

[0021] This invention introduces a lithium-replenishing additive, a conjugated furan glycol lithium compound, into the electrolyte of a lithium-ion battery. During battery charging, this compound releases lithium ions through oxidation at the positive electrode, compensating for the loss of active lithium at the negative electrode due to side reactions or irreversible damage, thus achieving the purpose of replenishing lithium in the electrolyte. Furthermore, this lithium-replenishing additive generates a conjugated carbonyl-ene-carbonyl structure while releasing lithium ions. This structure diffuses to the negative electrode and participates in the formation of the SEI film. This process involves quenching free radicals or stabilizing negative ions; therefore, it does not consume the negative electrode charge and does not cause loss of active lithium. Simultaneously, it stabilizes the negative electrode SEI, enhancing the cycle stability of the battery. Additionally, according to the molecular design, the functional groups modified at the 3 and 4 positions of the five-membered ring of the furan backbone can introduce the SEI during negative electrode film formation along with the conjugated carbonyl-ene-carbonyl structure generated after oxidation. Its chlorinated, fluorinated, or sulfonate groups can increase the ionic conductivity of the SEI, further reducing polarization and extending cycle life. Detailed Implementation

[0022] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features can be combined with each other. It should also be understood that the terminology used in the embodiments of the present invention is for describing specific implementation schemes and not for limiting the scope of protection of the present invention. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or according to the conditions recommended by the respective manufacturers.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Unless otherwise stated or in case of conflict, the terms or phrases used herein have the following meanings: "a plurality of," "multiple," "repeatedly," etc., in this invention refer to a quantity greater than 2 or equal to 2 unless otherwise specified. For example, "one or more" means one or more of two.

[0024] In this document, terms such as "preferred," "better," "more suitable," and "ideal" are merely descriptions of more effective implementation methods or embodiments and should be understood not to limit the scope of protection of this invention. If multiple "preferred" terms appear in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "preferred" term shall be independent.

[0025] In this document, terms such as "further," "even further," and "particularly" are used for descriptive purposes to indicate differences in content, but should not be construed as limiting the scope of protection of this invention.

[0026] In this document, when referring to numerical ranges, unless otherwise specified, the distribution of selectable values ​​within a numerical range is considered continuous, including the two endpoints of the range (i.e., the minimum and maximum values), and every value between these two endpoints. When multiple numerical ranges are provided to describe a feature or property, these numerical ranges can be combined.

[0027] In this article, lithium replenishment equivalent refers to the actual amount of lithium ions that 1 mol of lithium replenishment additive can replenish in the electrolyte.

[0028] As is well known, film-forming side reactions occur during the first charge cycle of a lithium-ion battery. This process forms an SEI film, stabilizing the positive and negative electrode interface, but also consumes charge and reduces the amount of active lithium. Specifically, during charging, the positive electrode active material is oxidized, donating electrons and lithium ions, while the negative electrode is reduced and accepts electrons. It should be noted that due to the presence of film-forming side reactions, the graphite intercalation of lithium ions may not occur when the negative electrode is reduced. Therefore, during discharge, less lithium ions can be extracted from the negative electrode and returned to the positive electrode; this capacity difference between the positive electrode and the negative electrode is the so-called active lithium loss. This application provides a lithium-ion battery electrolyte, a lithium-ion battery, and a lithium replenishment method thereof. By introducing a lithium replenishment additive into the electrolyte, this additive releases lithium ions during battery charging through oxidation at the positive electrode, replenishing the active lithium loss at the negative electrode caused by side reactions or irreversible reactions, thus achieving lithium replenishment.

[0029] The lithium-ion battery electrolyte of this invention comprises an organic solvent, a lithium salt, and a lithium replenishing additive, wherein both the lithium salt and the lithium replenishing additive are soluble in the organic solvent. The lithium replenishing additive is selected from conjugated furan glycol lithium compounds. During the first charge of the battery, these compounds undergo lithium loss through oxidation at the positive electrode, generating a conjugated carbonyl-olefin-carbonyl structure and releasing lithium ions. This process achieves the release of extra lithium at the positive electrode, realizing lithium replenishment through the additive. Furthermore, the conjugated carbonyl-olefin-carbonyl structure generated by its oxidation can diffuse to the negative electrode and participate in the formation of the SEI film. This process is often accompanied by quenching free radicals or stabilizing negative ions, without consuming the negative electrode charge or causing loss of active lithium. Simultaneously, it can stabilize the negative electrode SEI and enhance the cycle stability of the battery.

[0030] In some embodiments, the conjugated lithium furanyl glycol compound includes at least one of lithium 2,5-furanyl glycol and its derivatives; that is, the conjugated lithium furanyl glycol compound may be selected from lithium 2,5-furanyl glycol, or from one or more derivatives of lithium 2,5-furanyl glycol, or from a composition of lithium 2,5-furanyl glycol and its derivatives. The general structural formula of the derivatives of lithium 2,5-furanyl glycol is shown below:

[0031]

[0032] In the formula, R1 and R2 are each independently selected from hydrogen atoms, halogen atoms, and carbon atoms. 1-12 Hydrocarbon group or hydrocarbon oxygen substituent, C 1-12 It contains any one of the following substituents: carbonyl group, sulfonic acid group, sulfate ester group, or silyl vinyl group. The halogen atom is selected from fluorine, chlorine, bromine, iodine, etc.; C 1-12 Hydrocarbon group or hydrocarbon oxygen substituent refers to a hydrocarbon group or hydrocarbon oxygen substituent having 1 to 12 carbon atoms, for example, a C1 hydrocarbon group, or a C5 hydrocarbon group, or a C8 hydrocarbon group, or a C 12 Hydrocarbon group, etc.; C 1-12 The carbonyl, sulfonic acid, sulfate, or silyl vinyl substituents represent substituents having 1 to 12 carbon atoms, and the substituents contain any one or more of carbonyl, sulfonic acid, sulfate, or silyl vinyl groups. For example, a C1 substituent may contain a carbonyl group; or a C3 substituent may contain both a sulfonic acid and a sulfate group; or a C7 substituent may contain a silyl vinyl group; C... 12The substituents, including those containing sulfonate groups, etc., will not be listed here. It should be noted that R1 and R2 can be the same group or different groups; for example, R1 can be a hydrogen atom and R2 a sulfonic acid group; or both R1 and R2 can be sulfate ester groups. Based on molecular design, the functional groups modified at the 3 and 4 positions of the five-membered ring of the furan backbone can introduce SEI during negative electrode film formation along with the conjugated carbonyl-ene-carbonyl structure generated after oxidation. Their chloro, fluorinated, or sulfonate groups can increase the ionic conductivity of the SEI, further reducing polarization and extending cycle life.

[0033] In some embodiments, the lithium supplementing additive may be selected from at least one of compounds A to L:

[0034]

[0035]

[0036] The lithium supplement additive can be any one of compounds A to L, such as compound A, compound B, or compound C; the lithium supplement additive can also be any combination of two or more of compounds A to L, such as a combination of compounds A and B, or a combination of compounds E and F, or a combination of compounds G, H and I, etc., which will not be listed here.

[0037] This invention calculates the lithium equivalent of compounds A to L in the electrolyte. The equivalent conversion of each compound is shown in Table 1.

[0038] Table 1: Lithium Equivalent Conversion Table for Compounds A to L

[0039]

[0040]

[0041] The amount of lithium-replenishing additive added to the electrolyte is calculated based on its lithium-replenishing equivalent. In some embodiments, the lithium-replenishing equivalent of the lithium-ion battery electrolyte is 0.1–1 mmol / Ah relative to the battery capacity, for example, 0.1 mmol / Ah, 0.5 mmol / Ah, 0.8 mmol / Ah, or 1 mmol / Ah, etc. The inventors have found that if the amount of lithium-replenishing additive added is too small, the lithium-replenishing effect will be insufficient; if the amount added is too large, the film-forming resistance of the product will be high, affecting the cycle performance of the battery. Therefore, only when the amount of lithium-replenishing additive added is within an appropriate range can optimal results be achieved.

[0042] Lithium salts, as electrolyte salts, release a large number of active lithium ions upon dissolution in organic solvents, resulting in electrolytes with good conductivity. To obtain optimal electrolytes, lithium salts typically possess the following characteristics: low dissociation energy, high solubility, good stability, excellent SEI film-forming properties, and good passivation of aluminum current collectors. Low dissociation energy ensures high conductivity in the electrolyte formed after lithium salt dissolution, enabling high battery rates; high solubility ensures sufficient lithium ions for transport within the electrolyte; good stability prevents lithium salts from reacting with other components when the battery operates at high voltage and high temperature; excellent SEI film-forming properties prevent continuous electrolyte consumption during subsequent cycles; good passivation of aluminum current collectors prevents corrosion of the aluminum foil under high voltage; and low cost, being non-toxic and pollution-free.

[0043] As an example, the lithium salt is selected from at least one of lithium hexafluorophosphate (LiPF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium tetrafluoroborate (LiBF4), lithium di(oxalato)borate (LiBOB), lithium di(oxalato)borate (LiDFOB), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and lithium difluorophosphate (LiPF2O2). That is, the lithium salt can be any one or more of the lithium salts listed above, for example, lithium hexafluorophosphate, or lithium bis(fluorosulfonyl)imide, or a combination of lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide in any proportion. Preferably, the lithium salt is selected from lithium hexafluorophosphate, which has good overall performance, or lithium hexafluorophosphate is the main component with appropriate amounts of other lithium salts added to take advantage of their strengths and improve electrolyte performance. The concentration of the lithium salt can be set according to conventional methods in the art. For example, the concentration of lithium salt in the electrolyte is 0.1–2 mol / L, further 0.5–1.0 mol / L, such as 0.5 mol / L, 0.8 mol / L, or 1.0 mol / L, etc. An organic solvent is used to dissolve the electrolyte salt and the lithium-replenishing additive; the organic solvent can be a combination of solvents conventional in the art. Preferably, the organic solvent includes cyclic carbonates and chain carbonates; the combined solvent can offer advantages over a single solvent, thus enhancing the performance of the electrolyte. As an example, the cyclic carbonate includes one or both of ethylene carbonate (EC) and propylene carbonate (PC). For example, the cyclic carbonate can be ethylene carbonate, propylene carbonate, or a mixture of ethylene carbonate and propylene carbonate in any proportion. Chain carbonates include at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC). That is, chain carbonates can be any of the types listed above, such as dimethyl carbonate, diethyl carbonate, or ethyl methyl carbonate; or they can be a combination of any two or three of the types listed above mixed in any proportion, such as a combination of dimethyl carbonate and diethyl carbonate, or a combination of diethyl carbonate and ethyl methyl carbonate, or a combination of dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0044] In some embodiments, functional additives may be added to the lithium-ion battery electrolyte, and the types of functional additives can be selected according to actual needs. For example, functional additives may be selected from one or more of vinylene carbonate (VC), fluoroethylene carbonate (FEC), 1,3-propanesulfonate lactone (PS), and vinyl sulfate (DTD). The addition of fluoroethylene carbonate improves the performance of the formed negative electrode interface film (SEI film), forming a dense structural layer without increasing impedance, preventing further decomposition of the electrolyte, and improving the low-temperature performance of the electrolyte. The addition of 1,3-propanesulfonate lactone helps improve the battery's cycle life and high-temperature performance and suppresses gas production. The addition of vinyl sulfate can suppress the initial capacity loss of the battery, reduce battery expansion after high-temperature storage, and improve battery charge-discharge performance and cycle life. In other embodiments, functional additives may also be the types of additives not disclosed above.

[0045] It should be noted that the lithium supplement additive of the present invention can be obtained through general commercial channels or prepared using conventional methods in the art.

[0046] The lithium-ion battery electrolyte of the present invention can be prepared according to conventional preparation methods in the art. For example, an organic solvent is prepared in a glove box with an argon atmosphere containing less than 10 ppm of water. The fully dried lithium salt is dissolved in the organic solvent, and a lithium supplementation additive is added and mixed evenly to obtain the electrolyte.

[0047] This invention also provides a lithium-ion battery, comprising a positive electrode, a negative electrode, a separator, and an electrolyte. The separator is disposed between the positive and negative electrodes, serving as an isolation layer; the electrolyte conducts ions between the positive and negative electrodes. During charging and discharging, lithium ions repeatedly insert and extract between the positive and negative electrodes. The electrolyte is the lithium-ion battery electrolyte described above. Due to the presence of a lithium-replenishing additive in the electrolyte, during charging, the additive releases lithium ions through oxidation at the positive electrode, compensating for the loss of active lithium at the negative electrode due to side reactions or irreversible damage, thus achieving lithium replenishment.

[0048] Specifically, the positive electrode includes a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector. The positive current collector can be made of a material with good conductivity and mechanical strength, such as aluminum foil. The positive current collector has two surfaces opposite each other in its thickness direction, and the positive active material layer is disposed on either or both of these opposing surfaces. The positive active material layer includes a positive electrode material, a positive electrode conductive agent, and a positive electrode binder. No specific limitations are placed on the positive electrode material, positive electrode conductive agent, and positive electrode binder here; those skilled in the art can select them according to actual needs. As an example, the positive electrode material can be selected from ternary materials or lithium-containing phosphates. Ternary materials include lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese oxide doped with metal ions, lithium nickel cobalt aluminum oxide doped with metal ions, etc.; lithium-containing phosphates include lithium manganese iron phosphate, lithium iron phosphate, lithium manganese phosphate, etc. The positive electrode binder is selected, for example, from polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE). The positive electrode conductive agent is selected from one of carbon black, acetylene black, graphene, carbon nanotubes, carbon nanofibers, etc., or a combination of two or more in any proportion.

[0049] The negative electrode sheet includes a negative current collector and a negative active material layer disposed on at least one surface of the negative current collector. The negative current collector can be made of a material with good conductivity and mechanical strength, such as copper foil. The negative current collector has two surfaces opposite each other in its own thickness direction, and the negative active material layer is disposed on either or both of the two opposite surfaces of the negative current collector. The negative active material layer includes a negative electrode material, a negative electrode conductive agent, a negative electrode binder, and a thickener. The specific types of negative electrode material, negative electrode conductive agent, negative electrode binder, and thickener are not specifically limited here; those skilled in the art can select them according to actual needs.

[0050] As an example, the negative electrode material is selected from carbon and / or silicon negative electrode materials, such as elemental silicon, silicon oxides, silicon carbide, graphite, etc., where graphite can be natural graphite, artificial graphite, soft carbon, hard carbon, etc. The negative electrode conductive agent is selected from one of carbon black, acetylene black, graphene, carbon nanotubes, carbon nanofibers, etc., or a combination of two or more in any proportion. The negative electrode binder is selected from any one of polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), styrene-butadiene rubber (SBR), or a combination of several in any proportion; the thickener is selected from carboxymethyl cellulose (CMC).

[0051] The membrane is selected from conventional types in the art, such as a 12μm polypropylene (PP) porous membrane.

[0052] The preparation of lithium-ion batteries follows conventional methods, as illustrated below:

[0053] Preparation of the positive electrode sheet: The positive electrode material, positive electrode conductive agent, and positive electrode binder are dispersed in a solvent (e.g., N-methylpyrrolidone, abbreviated as NMP) to form a uniform positive electrode slurry. The positive electrode slurry is coated onto the positive electrode current collector, and after drying, cold pressing, and other processes, the positive electrode sheet is obtained. The proportions of the components in the positive electrode slurry can be set according to conventional proportions and are not limited here.

[0054] Preparation of the negative electrode sheet: The negative electrode material, negative electrode binder, thickener, and negative electrode conductive agent are dispersed in deionized water to form a uniform negative electrode slurry; the negative electrode slurry is coated onto the negative electrode current collector, and after drying, cold pressing, and other processes, the negative electrode sheet is obtained. The proportions of the components in the negative electrode slurry can be set according to conventional proportions and are not limited here.

[0055] Battery assembly: The prepared negative electrode sheet, separator, and positive electrode sheet are stacked in sequence, with the separator positioned between the positive and negative electrode sheets to provide isolation. Then, an aluminum-plastic film is wrapped around the separator to obtain a dry cell. The dry cell is then transferred to a vacuum oven and dried at 120°C. The prepared electrolyte is injected into the dry cell and sealed. After processes such as standing, hot and cold pressing, formation, clamping, and capacity testing, the finished lithium-ion battery is obtained.

[0056] This invention also provides a method for replenishing lithium in a lithium-ion battery. The method includes: injecting the aforementioned lithium-ion battery electrolyte into an assembled lithium-ion battery, and replenishing lithium by charging the battery. The assembled lithium-ion battery refers to a dry cell formed by stacking a positive electrode, a negative electrode, and a separator, and then encasing them in an aluminum-plastic film. During electrolyte injection, the amount of electrolyte injected is determined by the battery capacity. Typically, the amount of electrolyte injected is 3–10 g / Ah; in this application, the amount of electrolyte injected is 3.6 g / Ah. The voltage for the initial charging of the battery is 2.8–4.2 V. This potential range does not exceed the battery's own operating voltage range; therefore, electrolyte decomposition is reduced.

[0057] During battery charging, the lithium-replenishing additive in the electrolyte is oxidized at the positive electrode to generate a conjugated carbonyl-olefin-carbonyl structure and release lithium ions, thereby achieving additional lithium release at the positive electrode. Furthermore, the conjugated carbonyl-olefin-carbonyl structure participates in the film-forming reaction of the SEI film at the negative electrode, enhancing the stability of the SEI film and thus improving the cycle stability of the battery.

[0058] The technical solution of the present invention will be described in detail below through several specific embodiments and comparative examples. Unless otherwise stated, the raw materials and reagents used in the following embodiments are commercially available products or can be prepared by conventional methods in the art.

[0059] Example 1

[0060] An organic solvent was prepared by uniformly mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio of 20:20:60 in an argon-atmosphere glove box with a water content of <10 ppm. Fully dried lithium salt lithium hexafluorophosphate (LiPF6) was added to the organic solvent and mixed thoroughly. Then, lithium-replenishing additive compound A was added and mixed thoroughly to obtain the electrolyte. The concentration of LiPF6 was 1 mol / L. The actual amount of compound A added was 0.05 mmol / Ah, and its lithium-replenishing equivalent was 0.1 mmol / Ah.

[0061] Example 2

[0062] The difference between this embodiment and Example 1 is that the actual amount of compound A added is 0.25 mmol / Ah, and its lithium equivalent is 0.5 mmol / Ah.

[0063] Example 3

[0064] The difference between this embodiment and Example 1 is that the actual amount of compound A added is 0.5 mmol / Ah, and its lithium equivalent is 1 mmol / Ah.

[0065] Comparative Example 1

[0066] The difference between this comparative example and Example 1 is that compound A was not added.

[0067] Comparative Example 2

[0068] The difference between this comparative example and Example 1 is that the actual amount of compound A added is 0.005 mmol / Ah, and its lithium equivalent is 0.01 mmol / Ah.

[0069] Comparative Example 3

[0070] The difference between this comparative example and Example 1 is that the actual amount of compound A added is 0.75 mmol / Ah, and its lithium equivalent is 1.5 mmol / Ah.

[0071] Example 4

[0072] An organic solvent was prepared by uniformly mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio of 20:20:60 in an argon-atmosphere glove box with a water content of <10 ppm. Fully dried lithium salt lithium hexafluorophosphate (LiPF6) was added to the organic solvent and mixed thoroughly. Then, lithium-replenishing additive compound B was added and mixed thoroughly to obtain the electrolyte. The concentration of LiPF6 was 1 mol / L; the actual amount of compound B added was 0.05 mmol / Ah, and its lithium-replenishing equivalent was 0.1 mmol / Ah.

[0073] Example 5

[0074] The difference between this embodiment and Example 4 is that the actual amount of compound B added is 0.25 mmol / Ah, and its lithium equivalent is 0.5 mmol / Ah.

[0075] Example 6

[0076] The difference between this embodiment and Example 4 is that the actual amount of compound B added is 0.5 mmol / Ah, and its lithium equivalent is 1 mmol / Ah.

[0077] Comparative Example 4

[0078] The difference between this comparative example and Example 4 is that the actual amount of compound B added is 0.005 mmol / Ah, and its lithium equivalent is 0.01 mmol / Ah.

[0079] Comparative Example 5

[0080] The difference between this comparative example and Example 4 is that the actual amount of compound B added is 0.75 mmol / Ah, and its lithium equivalent is 1.5 mmol / Ah.

[0081] Example 7

[0082] An organic solvent was prepared by uniformly mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a glove box under an argon atmosphere with a water content of <10 ppm at a volume ratio of 20:20:60. Fully dried lithium salt lithium hexafluorophosphate (LiPF6) was added to the organic solvent and mixed thoroughly. Then, lithium-replenishing additive compound C was added and mixed thoroughly to obtain the electrolyte. The concentration of LiPF6 was 1 mol / L; the actual amount of compound C added was 0.05 mmol / Ah, and its lithium-replenishing equivalent was 0.1 mmol / Ah.

[0083] Example 8

[0084] The difference between this embodiment and Example 7 is that the actual amount of compound C added is 0.25 mmol / Ah, and its lithium equivalent is 0.5 mmol / Ah.

[0085] Example 9

[0086] The difference between this embodiment and Example 7 is that the actual amount of compound C added is 0.5 mmol / Ah, and its lithium equivalent is 1 mmol / Ah.

[0087] Comparative Example 6

[0088] The difference between this comparative example and Example 7 is that the actual amount of compound C added is 0.005 mmol / Ah, and its lithium equivalent is 0.01 mmol / Ah.

[0089] Comparative Example 7

[0090] The difference between this comparative example and Example 7 is that the actual amount of compound C added is 0.75 mmol / Ah, and its lithium equivalent is 1.5 mmol / Ah.

[0091] Example 10

[0092] An organic solvent was prepared by uniformly mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a glove box under an argon atmosphere with a water content of <10 ppm at a volume ratio of 20:20:60. Fully dried lithium salt lithium hexafluorophosphate (LiPF6) was added to the organic solvent and mixed thoroughly. Then, lithium-replenishing additive compound D was added and mixed thoroughly to obtain the electrolyte. The concentration of LiPF6 was 1 mol / L; the actual amount of compound D added was 0.05 mmol / Ah, and its lithium-replenishing equivalent was 0.1 mmol / Ah.

[0093] Example 11

[0094] The difference between this embodiment and Example 10 is that the actual amount of compound D added is 0.25 mmol / Ah, and its lithium equivalent is 0.5 mmol / Ah.

[0095] Example 12

[0096] The difference between this embodiment and Example 10 is that the actual amount of compound D added is 0.5 mmol / Ah, and its lithium equivalent is 1 mmol / Ah.

[0097] Comparative Example 8

[0098] The difference between this comparative example and Example 10 is that the actual amount of compound D added is 0.005 mmol / Ah, and its lithium equivalent is 0.01 mmol / Ah.

[0099] Comparative Example 9

[0100] The difference between this comparative example and Example 10 is that the actual amount of compound D added is 0.75 mmol / Ah, and its lithium equivalent is 1.5 mmol / Ah.

[0101] Example 13

[0102] An organic solvent was prepared by uniformly mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a glove box under an argon atmosphere with a water content of <10 ppm at a volume ratio of 20:20:60. Fully dried lithium salt lithium hexafluorophosphate (LiPF6) was added to the organic solvent and mixed thoroughly. Then, lithium-replenishing additive compound E was added and mixed thoroughly to obtain the electrolyte. The concentration of LiPF6 was 1 mol / L; the actual amount of compound E added was 0.05 mmol / Ah, and its lithium-replenishing equivalent was 0.1 mmol / Ah.

[0103] Example 14

[0104] The difference between this embodiment and Example 13 is that the actual amount of compound E added is 0.25 mmol / Ah, and its lithium equivalent is 0.5 mmol / Ah.

[0105] Example 15

[0106] The difference between this embodiment and Example 13 is that the actual amount of compound E added is 0.5 mmol / Ah, and its lithium equivalent is 1 mmol / Ah.

[0107] Comparative Example 10

[0108] The difference between this comparative example and Example 13 is that the actual amount of compound E added is 0.005 mmol / Ah, and its lithium equivalent is 0.01 mmol / Ah.

[0109] Comparative Example 11

[0110] The difference between this comparative example and Example 13 is that the actual amount of compound E added is 0.75 mmol / Ah, and its lithium equivalent is 1.5 mmol / Ah.

[0111] Example 16

[0112] An organic solvent was prepared by uniformly mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a glove box under an argon atmosphere with a water content of <10 ppm at a volume ratio of 20:20:60. Fully dried lithium salt lithium hexafluorophosphate (LiPF6) was added to the organic solvent and mixed thoroughly. Then, lithium-replenishing additive compound F was added and mixed thoroughly to obtain the electrolyte. The concentration of LiPF6 was 1 mol / L; the actual amount of compound F added was 0.05 mmol / Ah, and its lithium-replenishing equivalent was 0.1 mmol / Ah.

[0113] Example 17

[0114] The difference between this embodiment and Example 16 is that the actual amount of compound F added is 0.25 mmol / Ah, and its lithium equivalent is 0.5 mmol / Ah.

[0115] Example 18

[0116] The difference between this embodiment and Example 16 is that the actual amount of compound F added is 0.5 mmol / Ah, and its lithium equivalent is 1 mmol / Ah.

[0117] Comparative Example 12

[0118] The difference between this comparative example and Example 16 is that the actual amount of compound F added was 0.005 mmol / Ah, and its lithium equivalent was 0.01 mmol / Ah.

[0119] Comparative Example 13

[0120] The difference between this comparative example and Example 16 is that the actual amount of compound F added was 0.75 mmol / Ah, and its lithium equivalent was 1.5 mmol / Ah.

[0121] Example 19

[0122] An organic solvent was prepared by uniformly mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio of 20:20:60 in an argon-atmosphere glove box with a water content of <10 ppm. Fully dried lithium salt lithium hexafluorophosphate (LiPF6) was added to the organic solvent and mixed thoroughly. Then, lithium-replenishing additive compound G was added and mixed thoroughly to obtain the electrolyte. The concentration of LiPF6 was 1 mol / L; the actual amount of compound G added was 0.05 mmol / Ah, and its lithium-replenishing equivalent was 0.1 mmol / Ah.

[0123] Example 20

[0124] The difference between this embodiment and Example 19 is that the actual amount of compound G added is 0.25 mmol / Ah, and its lithium equivalent is 0.5 mmol / Ah.

[0125] Example 21

[0126] The difference between this embodiment and Example 19 is that the actual amount of compound G added is 0.5 mmol / Ah, and its lithium equivalent is 1 mmol / Ah.

[0127] Comparative Example 14

[0128] The difference between this comparative example and Example 19 is that the actual amount of compound G added is 0.005 mmol / Ah, and its lithium equivalent is 0.01 mmol / Ah.

[0129] Comparative Example 15

[0130] The difference between this comparative example and Example 19 is that the actual amount of compound G added was 0.75 mmol / Ah, and its lithium equivalent was 1.5 mmol / Ah.

[0131] Example 22

[0132] An organic solvent was prepared by uniformly mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio of 20:20:60 in an argon-atmosphere glove box with a water content of <10 ppm. Fully dried lithium salt lithium hexafluorophosphate (LiPF6) was added to the organic solvent and mixed thoroughly. Then, lithium-replenishing additive compound H was added and mixed thoroughly to obtain the electrolyte. The concentration of LiPF6 was 1 mol / L; the actual amount of compound H added was 0.05 mmol / Ah, and its lithium-replenishing equivalent was 0.1 mmol / Ah.

[0133] Example 23

[0134] The difference between this embodiment and Example 22 is that the actual amount of compound H added is 0.25 mmol / Ah, and its lithium equivalent is 0.5 mmol / Ah.

[0135] Example 24

[0136] The difference between this embodiment and Example 22 is that the actual amount of compound H added is 0.5 mmol / Ah, and its lithium equivalent is 1 mmol / Ah.

[0137] Comparative Example 16

[0138] The difference between this comparative example and Example 22 is that the actual amount of compound H added is 0.005 mmol / Ah, and its lithium equivalent is 0.01 mmol / Ah.

[0139] Comparative Example 17

[0140] The difference between this comparative example and Example 22 is that the actual amount of compound H added was 0.75 mmol / Ah, and its lithium equivalent was 1.5 mmol / Ah.

[0141] Example 25

[0142] An organic solvent was prepared by uniformly mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a glove box under an argon atmosphere with a water content of <10 ppm at a volume ratio of 20:20:60. Fully dried lithium salt lithium hexafluorophosphate (LiPF6) was added to the organic solvent and mixed thoroughly. Then, lithium-replenishing additive compound I was added and mixed thoroughly to obtain the electrolyte. The concentration of LiPF6 was 1 mol / L. The actual amount of compound I added was 0.025 mmol / Ah, and its lithium-replenishing equivalent was 0.1 mmol / Ah.

[0143] Example 26

[0144] The difference between this embodiment and Example 25 is that the actual amount of compound I added is 0.125 mmol / Ah, and its lithium equivalent is 0.5 mmol / Ah.

[0145] Example 27

[0146] The difference between this embodiment and Example 25 is that the actual amount of compound I added is 0.25 mmol / Ah, and its lithium equivalent is 1 mmol / Ah.

[0147] Comparative Example 18

[0148] The difference between this comparative example and Example 25 is that the actual amount of compound I added was 0.0025 mmol / Ah, and its lithium equivalent was 0.01 mmol / Ah.

[0149] Comparative Example 19

[0150] The difference between this comparative example and Example 25 is that the actual amount of compound I added was 0.375 mmol / Ah, and its lithium equivalent was 1.5 mmol / Ah.

[0151] Example 28

[0152] An organic solvent was prepared by uniformly mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a glove box under an argon atmosphere with a water content of <10 ppm at a volume ratio of 20:20:60. Fully dried lithium salt lithium hexafluorophosphate (LiPF6) was added to the organic solvent and mixed thoroughly. Then, lithium-replenishing additive compound J was added and mixed thoroughly to obtain the electrolyte. The concentration of LiPF6 was 1 mol / L. The actual amount of compound J added was 0.025 mmol / Ah, and its lithium-replenishing equivalent was 0.1 mmol / Ah.

[0153] Example 29

[0154] The difference between this embodiment and Example 28 is that the actual amount of compound J added is 0.125 mmol / Ah, and its lithium equivalent is 0.5 mmol / Ah.

[0155] Example 30

[0156] The difference between this embodiment and Example 28 is that the actual amount of compound J added is 0.25 mmol / Ah, and its lithium equivalent is 1 mmol / Ah.

[0157] Comparative Example 20

[0158] The difference between this comparative example and Example 28 is that the actual amount of compound J added was 0.0025 mmol / Ah, and its lithium equivalent was 0.01 mmol / Ah.

[0159] Comparative Example 21

[0160] The difference between this comparative example and Example 28 is that the actual amount of compound J added was 0.375 mmol / Ah, and its lithium equivalent was 1.5 mmol / Ah.

[0161] Example 31

[0162] An organic solvent was prepared by uniformly mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a glove box under an argon atmosphere with a water content of <10 ppm at a volume ratio of 20:20:60. Fully dried lithium salt lithium hexafluorophosphate (LiPF6) was added to the organic solvent and mixed thoroughly. Then, lithium-replenishing additive compound K was added and mixed thoroughly to obtain the electrolyte. The concentration of LiPF6 was 1 mol / L; the actual amount of compound K added was 0.025 mmol / Ah, and its lithium-replenishing equivalent was 0.1 mmol / Ah.

[0163] Example 32

[0164] The difference between this embodiment and Example 25 is that the actual amount of compound K added is 0.125 mmol / Ah, and its lithium equivalent is 0.5 mmol / Ah.

[0165] Example 33

[0166] The difference between this embodiment and Example 25 is that the actual amount of compound K added is 0.25 mmol / Ah, and its lithium equivalent is 1 mmol / Ah.

[0167] Comparative Example 22

[0168] The difference between this comparative example and Example 25 is that the actual amount of compound K added was 0.0025 mmol / Ah, and its lithium equivalent was 0.01 mmol / Ah.

[0169] Comparative Example 23

[0170] The difference between this comparative example and Example 25 is that the actual amount of compound K added was 0.375 mmol / Ah, and its lithium equivalent was 1.5 mmol / Ah.

[0171] Example 34

[0172] An organic solvent was prepared by uniformly mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a glove box under an argon atmosphere with a water content of <10 ppm at a volume ratio of 20:20:60. Fully dried lithium salt lithium hexafluorophosphate (LiPF6) was added to the organic solvent and mixed thoroughly. Then, lithium-replenishing additive compound L was added and mixed thoroughly to obtain the electrolyte. The concentration of LiPF6 was 1 mol / L; the actual amount of compound L added was 0.025 mmol / Ah, and its lithium-replenishing equivalent was 0.1 mmol / Ah.

[0173] Example 35

[0174] The difference between this embodiment and Example 34 is that the actual amount of compound L added is 0.125 mmol / Ah, and its lithium equivalent is 0.5 mmol / Ah.

[0175] Example 36

[0176] The difference between this embodiment and Example 34 is that the actual amount of compound L added is 0.25 mmol / Ah, and its lithium equivalent is 1 mmol / Ah.

[0177] Comparative Example 24

[0178] The difference between this comparative example and Example 34 is that the actual amount of compound L added was 0.0025 mmol / Ah, and its lithium equivalent was 0.01 mmol / Ah.

[0179] Comparative Example 25

[0180] The difference between this comparative example and Example 34 is that the actual amount of compound L added was 0.375 mmol / Ah, and its lithium equivalent was 1.5 mmol / Ah.

[0181] To verify the technical effect of this application, the electrolytes prepared in Examples 1 to 36 and Comparative Examples 1 to 25 were injected into lithium iron phosphate batteries and high-nickel high-silicon batteries, respectively, and their cycle performance was tested. The test results are shown in Table 2.

[0182] The configuration process for high-nickel, high-silicon batteries is as follows:

[0183] (1) Cathode preparation: The cathode active material LiNi is prepared. 0.8 Co 0.1 Mn 0.1 O2, binder polyvinylidene fluoride (PVDF), and conductive agent acetylene black are mixed in a mass ratio of 98:1:1. N-methylpyrrolidone (NMP) solvent is added and the mixture is stirred in a vacuum mixer until the system is homogeneous and transparent to obtain a positive electrode slurry. The positive electrode slurry is uniformly coated onto a 16μm aluminum foil current collector, dried at room temperature, and then transferred to an oven for drying. After cold pressing and slitting, the positive electrode sheet is obtained.

[0184] (2) Negative electrode preparation: The negative electrode active material artificial graphite and silicon oxide compound, conductive agent Ketjen black, binder styrene-butadiene rubber, and thickener sodium carboxymethyl cellulose are mixed in a mass ratio of 87:9:2:1:1. Deionized water is added and the mixture is stirred thoroughly under vacuum to obtain a negative electrode slurry. The negative electrode slurry is uniformly coated on an 8μm copper foil current collector, dried at room temperature, transferred to an oven for drying, and then cold-pressed and slit to obtain a negative electrode sheet.

[0185] (3) Separator: Polypropylene film (PP) with a thickness of 12μm.

[0186] (4) Assembly: The positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes to provide isolation. Then, an aluminum-plastic film is wrapped around the separator and transferred to a vacuum oven at 120°C for drying. 3.6g of electrolyte (corresponding to 3mL of electrolyte) is injected and the separator is sealed. After standing, hot and cold pressing, formation, clamping, and capacity testing, a soft-pack battery (i.e., lithium-ion battery) with a capacity of 1Ah is finally prepared.

[0187] The specific steps and conditions for formation are as follows: After injecting the electrolyte, maintain a hot pressure environment of 0.1 MPa, charge at 0.02C for 17 minutes at 45°C in a static state, let it stand for 5 minutes, and then charge it to 0.3Ah at 0.02C. After that, cut off the gas bag and vacuum seal it, and let it stand at room temperature for 48 hours to complete the formation of the electrolyte.

[0188] The configuration process of lithium iron phosphate batteries is similar to that of high-nickel and high-silicon batteries, except that the ratio of the positive electrode material layer is as follows: positive electrode active material lithium iron phosphate, binder PVDF, and conductive agent acetylene black are in a mass ratio of 98:1:1.

[0189] The negative electrode active material layer was prepared by mixing graphite (negative electrode active material), acetylene black (conductive agent), styrene-butadiene rubber (binder), and sodium carboxymethyl cellulose (CMC) solution (thickener) in a mass ratio of 97:1:1:1. The performance of the prepared pouch cells was tested under the conditions shown below, and the results are shown in Table 2.

[0190] Loop testing:

[0191] At 45℃, the lithium-ion battery was cycled with a 1C / 1C current in the potential range of 2.8V to 4.2V. The discharge capacity of each cycle was recorded. When the battery capacity reached 80% of the capacity of the first cycle, the test was ended and the number of cycles was counted.

[0192] Table 2: High-temperature cycling performance of lithium-ion batteries prepared with electrolytes from Examples 1 to 36 and Comparative Examples 1 to 25

[0193]

[0194]

[0195]

[0196] As shown in Table 2, adding an appropriate amount of any one of the lithium-ion compounds (A-L) to the electrolyte significantly improved the high-temperature cycle performance of both lithium iron phosphate (LiFePO4) and high-silicon, high-nickel batteries compared to Comparative Example 1 (without lithium-ion additive). This indicates that the lithium-ion additive of this application achieved the lithium-ion replenishment effect of the electrolyte, thereby improving the cycle stability of the battery. Furthermore, the inventors also studied the effect of the amount of compounds (A-L) added on battery performance. The results in Table 2 show that as the amount of compound added to the electrolyte increases, the battery cycle performance initially improves gradually. However, once a certain amount is reached, the cycle performance begins to decline with further increases in the amount of compound added. This is because if the amount of lithium-ion additive added is too small, the amount of lithium replenishment is insufficient to compensate for the lithium loss at the negative electrode due to side reactions or irreversible losses; if the amount of lithium-ion additive added is too large, the film-forming resistance of its oxidation products is high, which in turn affects the battery cycle performance.

[0197] This invention adds a conjugated furan glycol lithium compound as a lithium replenishing additive to the electrolyte. During battery charging, the conjugated furan glycol lithium compound releases lithium ions through oxidation at the positive electrode, replenishing the active lithium lost at the negative electrode due to side reactions or irreversible damage, thus achieving lithium replenishment. This invention, through electrolyte lithium replenishment, can be used in lithium iron phosphate batteries and high-silicon, high-nickel batteries, achieving the purpose of lithium replenishment without compromising battery safety and stability. Therefore, this invention effectively overcomes some practical problems in existing technologies, thus possessing high utilization value and practical significance.

[0198] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A lithium-ion battery electrolyte, characterized in that, include: Organic solvents; Lithium salt, soluble in the organic solvent; and A lithium supplement additive, dissolved in the organic solvent, wherein the lithium supplement additive is selected from conjugated furan glycol lithium compounds.

2. The lithium-ion battery electrolyte according to claim 1, characterized in that, The conjugated lithium furan glycol compounds include at least one of lithium 2,5-furan glycol and its derivatives, the general structural formula of the lithium 2,5-furan glycol derivatives being shown below: R1 and R2 are each independently selected from hydrogen atoms, halogen atoms, and carbon atoms. 1-12 Hydrocarbon group or hydrocarbon oxygen substituent, C 1-12 It contains any one of the following: carbonyl group, sulfonic acid group, sulfate ester group, and silyl vinyl substituent.

3. The lithium-ion battery electrolyte according to claim 1, characterized in that, The lithium supplementation additive is selected from at least one of the following compounds:

4. The lithium-ion battery electrolyte according to claim 1, characterized in that, The amount of the lithium-replenishing additive added is calculated based on its lithium-replenishing equivalent, and the lithium-replenishing equivalent of the lithium-ion battery electrolyte is 0.1 to 1 mmol / Ah relative to the battery capacity.

5. The lithium-ion battery electrolyte according to claim 1, characterized in that, The lithium salt includes LiPF6, and the concentration of the lithium salt in the lithium-ion battery electrolyte is 0.1–2 mol / L.

6. The lithium-ion battery electrolyte according to claim 1, characterized in that, The organic solvent includes cyclic carbonates and chain carbonates, wherein the cyclic carbonates include one or both of ethylene carbonate and propylene carbonate, and the chain carbonates include at least one of dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

7. A lithium-ion battery, characterized in that, It includes a positive electrode, a negative electrode, a separator, and the lithium-ion battery electrolyte as described in any one of claims 1 to 6.

8. A method for replenishing lithium in a lithium-ion battery, characterized in that, include: The lithium-ion battery electrolyte according to any one of claims 1 to 6 is injected into the lithium-ion battery to replenish lithium during charging.

9. The lithium replenishment method according to claim 8, characterized in that, The charging voltage of the lithium-ion battery is 2.8 to 4.2V.

10. The lithium replenishment method according to claim 8, characterized in that, During charging, the lithium-ion battery electrolyte contains lithium-ion battery additives that are oxidized at the positive electrode of the lithium-ion battery to generate a conjugated carbonyl-olefin-carbonyl structure and release lithium ions.

Images