Repair method of lithium battery positive electrode material and application thereof

Abstract

The invention provides a repairing method of a lithium battery positive electrode material, which comprises the following steps: S1, mixing raw materials including a quaternary ammonium salt compound, an amine compound and a lithium salt to prepare a eutectic solution; s2, immersing a positive plate of the lithium battery into the eutectic solution, and carrying out electrochemical treatment to obtain a lithium-supplemented positive plate; s3, separating the lithium-supplemented positive plate to obtain a lithium-supplemented positive electrode material, and calcining the lithium-supplemented positive electrode material to obtain a repaired positive electrode material; the repairing method provided by the invention can meet the requirements of different lithium supplementing amounts, so that the repaired positive electrode material has good electrochemical performance, and meanwhile, secondary pollution can be avoided.

Description

Technical Field

[0001] The present disclosure relates to the technical field of lithium battery materials, and in particular to a method for repairing a lithium battery positive electrode material and an application thereof. Background Art

[0002] Lithium batteries have the characteristics of high energy density, high coulomb efficiency and long cycle life, making them the main power source for portable electronic products and electric vehicles. It is expected that the global manufacturing capacity of lithium-ion batteries will increase significantly at a rate of hundreds of gigawatt-hours per year in the next five years. Waste lithium-ion batteries are not only a source of garbage pollution, but their heavy metal elements will cause great soil, water and air pollution if directly exposed to the natural environment. The recycling of scrapped lithium battery materials can effectively supplement the supply chain, make full use of metal material resources, and avoid waste and loss.

[0003] At present, the widely used battery recycling methods mainly include pyrometallurgy, hydrometallurgy and direct recycling to recycle lithium battery positive electrode materials. Pyrometallurgy requires high-temperature smelting and multi-stage purification and separation processes, which consumes a lot of energy; while hydrometallurgy requires acid leaching and complex extraction and precipitation steps to recover valuable metal elements, and there are a lot of wastewater treatment problems. The direct recovery method combines the physical separation process to separate and collect positive electrode materials, as well as the subsequent lithium replenishment process to repair the composition and structural defects of electrode materials, which greatly shortens the recycling process and reduces energy consumption and emissions. The current mainstream lithium replenishment technologies include solid sintering method, hydrothermal method, etc. Although the solid sintering method is widely used in the synthesis of positive electrode materials, it has extremely high precision requirements for the measurement of lithium deficiency in the material repair process. At present, ICP is generally used for quantitative element analysis, which has complex procedures, long time consumption, and difficult error control. In addition, due to the sensitivity of high-nickel ternary materials to water, the hydrothermal method has certain disadvantages and produces a large amount of sewage. Summary of the invention

[0004] In view of the problems existing in the prior art, the present disclosure aims to provide a method for repairing lithium battery positive electrode materials that does not require measuring the amount of lithium deficiency, can greatly simplify the recycling process and shorten the production cycle.

[0005] The present disclosure provides a method for repairing a positive electrode material of a lithium battery, the method comprising the following steps:

[0006] S1: mixing raw materials including a quaternary ammonium salt compound, an amine compound and a lithium salt to prepare a eutectic solution;

[0007] S2: immersing the positive electrode sheet of the lithium battery in the eutectic solution and performing electrochemical treatment to obtain a positive electrode sheet after lithium supplementation;

[0008] S3: separating the lithium-replenished positive electrode sheet to obtain a lithium-replenished positive electrode material, and then calcining the lithium-replenished positive electrode material to obtain a repaired positive electrode material.

[0009] In one aspect of the present disclosure, in S1, a mixture A comprising the quaternary ammonium salt compound and the amine compound is first mixed at 50°C-90°C to obtain a mixed solution, and then a mixture B comprising the lithium salt is added to the mixed solution to obtain the low eutectic solution.

[0010] In one aspect of the present disclosure, the molar ratio of the quaternary ammonium salt compound to the amine compound is 1:(0.5-5).

[0011] In one aspect of the present disclosure, in S1, the molar ratio of the quaternary ammonium salt compound, the amine compound and the lithium salt is 1:(0.5-5):(0.1-2).

[0012] In one aspect of the present disclosure, the quaternary ammonium salt compound includes at least one of choline chloride, choline acetate and acetylcholine.

[0013] In one aspect of the present disclosure, the amine compound includes at least one of urea, ethanolamine and triethanolamine.

[0014] In one aspect of the present disclosure, the lithium salt includes at least one of lithium chloride, lithium bromide, lithium iodide, lithium hydroxide, lithium nitrate, lithium carbonate and lithium perchlorate.

[0015] In one aspect of the present disclosure, wherein, in S2,

[0016] First, immerse the positive electrode sheet of the lithium battery in the low eutectic solution, and connect the positive electrode sheet of the lithium battery to the working electrode of the main repair equipment;

[0017] The main repair device is discharged at room temperature, and after the voltage is constant, it is maintained for 5-10 hours to obtain a positive electrode sheet after electrochemical treatment; then the positive electrode sheet after electrochemical treatment is taken out, washed and dried to obtain the positive electrode sheet after lithium supplementation.

[0018] In another aspect of the present disclosure, wherein, in S2,

[0019] First, immerse the positive electrode of the lithium battery in a eutectic solution of lithium chloride, and connect the positive electrode of the lithium battery to the working electrode of the main repair equipment;

[0020] At room temperature, the main repair device is discharged, and after the voltage is constant, it is maintained for 5-10 hours to obtain a positive electrode sheet after electrochemical treatment;

[0021] The positive electrode sheet after the electrochemical treatment is taken out, washed and dried to obtain the positive electrode sheet after lithium supplementation.

[0022] In one aspect of the present disclosure, in S2, the main repair device is selected from one of a charging and discharging device, a voltage and current stabilizing device, or an electrochemical workstation.

[0023] In one aspect of the present disclosure, in S2, a discharge current of the primary repair device is less than or equal to 5 mA.

[0024] In one aspect of the present disclosure, preferably, in S2, the discharge current of the primary repair device is 0.01-0.5 mA.

[0025] In one aspect of the present disclosure, more preferably, in S2, the discharge current of the primary repair device is 0.1-0.3 mA.

[0026] In one aspect of the present disclosure, in S3, an organic solvent is used to immerse the positive electrode sheet after lithium replenishment to separate the positive electrode material after lithium replenishment; the positive electrode material after lithium replenishment is then filtered and dried, and then calcined at 700°C-1000°C for 2-5 hours to obtain the repaired positive electrode material.

[0027] In one aspect of the present disclosure, the positive electrode sheet of the waste lithium battery includes a positive electrode active material, and the positive electrode active material includes one or more of lithium transition metal oxides, olivine-structured lithium-containing phosphates and their respective modified compounds.

[0028] In one aspect of the present disclosure, the lithium transition metal oxide is selected from the general formula Li a Ni x Co y M z O 2 One or more of the lithium transition metal oxides, wherein M includes at least one of Mn, Al, Mg, Cr, Ca, Zr, Mo, Ag, and Nb, 0.9≤a≤1.1, 0≤x<1, and 0≤y≤1.

[0029] In one aspect of the present disclosure, the olivine-structured lithium-containing phosphate is selected from the group consisting of LiM x Fe 1-x PO 4 At least one of the lithium-containing phosphates.

[0030] In one aspect of the present disclosure, the organic solvent is selected from N-methylpyrrolidone.

[0031] In one aspect of the present disclosure, the repair method comprises

[0032] S1: Mix choline chloride and urea, stir at 50°C-90°C for 20-60 minutes, then add lithium chloride, and continue stirring until the lithium chloride is completely dissolved to obtain a low eutectic solution of lithium chloride;

[0033] S2: immersing the positive electrode in a low eutectic solution of lithium chloride and connecting it to the working electrode of the electrochemical workstation. At room temperature, the electrochemical workstation is discharged at a current of less than 5 mA. After the voltage is constant, it is maintained for 5-10 hours to obtain an electrochemically treated positive electrode sheet. The electrochemically treated positive electrode sheet is taken out, washed and dried to obtain a lithium-supplemented positive electrode sheet.

[0034] S3: using an organic solvent to soak the positive electrode sheet after lithium supplementation to separate the positive electrode material after lithium supplementation; filtering and drying the positive electrode material after lithium supplementation, and then calcining it at 700° C.-1000° C. for 2-5 hours to obtain a repaired positive electrode material.

[0035] In one aspect of the present disclosure, the repair method comprises

[0036] S1: Mix choline chloride and urea, stir at 80°C for 30 minutes, then add lithium chloride, and continue stirring until the lithium chloride is completely dissolved to obtain a low eutectic solution of lithium chloride;

[0037] S2: immersing the positive electrode in a low eutectic solution of lithium chloride and connecting it to the working electrode of the electrochemical workstation. At room temperature, the electrochemical workstation is discharged at a current of less than 5 mA. After the voltage is constant, it is maintained for 6-8 hours to obtain an electrochemically treated positive electrode sheet. The electrochemically treated positive electrode sheet is taken out, washed with ethanol, and then vacuum dried to obtain a lithium-supplemented positive electrode sheet.

[0038] S3: using N-methylpyrrolidone to soak the lithium-supplemented positive electrode sheet to separate the lithium-supplemented positive electrode material; filtering and drying the lithium-supplemented positive electrode material, and then calcining it at 800° C. for 3 hours to obtain a repaired positive electrode material.

[0039] In one aspect of the present disclosure, the primary repair device is selected from an electrochemical workstation.

[0040] In one aspect of the present disclosure, in S2, when the primary repair device is an electrochemical workstation, the counter electrode is selected from a graphite electrode, and the reference electrode is selected from an Ag / AgCl electrode.

[0041] The present disclosure also provides a lithium battery positive electrode material, which is obtained by the above-mentioned repair method.

[0042] The present disclosure also provides a lithium battery, which includes a positive electrode sheet and a negative electrode sheet. The positive electrode sheet includes a positive electrode collector and a positive electrode active material layer disposed on the positive electrode collector. The positive electrode active material layer includes the above-mentioned lithium battery positive electrode material.

[0043] The present disclosure utilizes the adaptability of electrochemical lithium supplementation, and utilizes the electrochemical characteristics of the positive electrode material to supplement the missing lithium ions in the crystal structure, while avoiding the error and time consumption caused by ICP measurement of the missing amount of lithium, and ensuring the rationality of the amount of lithium supplementation (neither too little nor too much). In addition, the present disclosure can also provide an anhydrous lithium supplementation environment for ternary high-nickel materials, avoiding the side reactions that produce a negative impact on their structural morphology during the recovery process.

[0044] Beneficial effects:

[0045] (1) Compared with the pyrometallurgy and hydrometallurgy used in the prior art, the repair method provided by the present disclosure can be implemented at room temperature and does not require acid leaching, which can effectively reduce costs and energy consumption. The low eutectic solution involved in the present disclosure is degradable to avoid secondary pollution.

[0046] (2) The repair method provided by the present disclosure does not require the measurement of the amount of lithium deficiency in the positive electrode sheet, and is adaptive and can meet different requirements for lithium replenishment.

[0047] (3) The low eutectic solution used in the present invention avoids the surface damage of the aqueous solution to the ternary material, and can also avoid the side reaction of the aqueous solution on the surface of the high-nickel ternary material, so that the repaired positive electrode material has good electrochemical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 A schematic diagram of the electrochemical lithium replenishment of Example 1 is shown;

[0049] Figure 2 The curve showing the voltage change over time of the electrochemical workstation during the electrochemical lithium replenishment process of Example 1 is shown. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solution and advantages of the present disclosure clearer, the technical solution of the present disclosure will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all the embodiments. The relevant embodiments described herein are illustrative and are used to provide a basic understanding of the present disclosure. The embodiments of the present disclosure should not be interpreted as limiting the present disclosure.

[0051] the term:

[0052] For simplicity, only some numerical ranges are specifically disclosed herein. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, and any upper limit can be combined with any other upper limit to form an unspecified range. In addition, each separately disclosed point or single value can itself be combined as a lower limit or upper limit with any other point or single value or with other lower limits or upper limits to form an unspecified range.

[0053] In this article, the terms "comprises", "comprising" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device that includes the element.

[0054] In the description herein, unless otherwise specified, “above” and “below” include the number.

[0055] Unless otherwise specified, the terms used in this disclosure have the well-known meanings commonly understood by those skilled in the art. Unless otherwise specified, the numerical values ​​of the various parameters mentioned in this disclosure can be measured using various measurement methods commonly used in the art (for example, they can be tested according to the methods given in the embodiments of this disclosure).

[0056] The term "about" is used to describe and illustrate small changes. When used in conjunction with an event or situation, the term may refer to an example in which the event or situation occurs precisely and an example in which the event or situation occurs very approximately. For example, when used in conjunction with a numerical value, the term may refer to a range of variation of less than or equal to ±10% of the numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. In addition, amounts, ratios, and other numerical values ​​are sometimes presented in this article in a range format. It should be understood that such a range format is for convenience and simplicity, and should be flexibly understood to include not only numerical values ​​explicitly designated as range limits, but also all individual numerical values ​​or subranges encompassed within the range, as if each numerical value and subrange were explicitly designated.

[0057] A list of items connected by the terms "at least one of," "at least one of," "at least one of," or other similar terms may mean any combination of the listed items. For example, if items A and B are listed, the phrase "at least one of A and B" means only A; only B; or A and B. In another example, if items A, B, and C are listed, the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may contain a single component or multiple components. Item B may contain a single component or multiple components. Item C may contain a single component or multiple components.

[0058] Herein, the term "DES" is an abbreviation of Deep Eutectic Solvent, which means a eutectic solution.

[0059] The present disclosure is further described below in conjunction with specific embodiments. It should be understood that these specific embodiments are only used to illustrate the present disclosure and are not used to limit the scope of the present disclosure.

[0061] How to fix it:

[0062] In some embodiments of the present disclosure, taking the waste ternary lithium-ion battery as an example, the waste ternary lithium-ion battery is first discharged, and then the waste ternary lithium-ion battery is disassembled into three parts, namely ① shell and diaphragm, etc.; ② positive electrode sheet of the waste lithium battery and ③ negative electrode sheet of the waste lithium battery. Among them, ① shell and diaphragm, etc. and ③ negative electrode sheet of the waste lithium battery are recycled and processed separately by other methods.

[0063] In the present disclosure, the positive electrode sheets of the aforementioned waste lithium batteries and / or the positive electrode sheets used in the production line experiment or the positive electrode sheets in other cases are repaired according to the following steps:

[0064] S1: mixing raw materials including a quaternary ammonium salt compound, an amine compound and a lithium salt to prepare a eutectic solution;

[0065] S2: immersing the positive electrode sheet of the lithium battery in the eutectic solution and performing electrochemical treatment to obtain a positive electrode sheet after lithium supplementation;

[0066] S3: separating the lithium-replenished positive electrode sheet to obtain a lithium-replenished positive electrode material, and then calcining the lithium-replenished positive electrode material to obtain a repaired positive electrode material.

[0067] In the present disclosure, urea and choline chloride are combined as a hydrogen bond donor and a hydrogen bond acceptor, respectively, to form a low eutectic solution system, which can be used as a solvent to dissolve lithium salts; lithium chloride is dissolved in the low eutectic solution system as a lithium source, has good solubility and stability, and provides a lithium replenishment environment for the positive electrode of waste lithium batteries.

[0068] In some preferred embodiments of the present disclosure, in S1, a mixture A comprising the quaternary ammonium salt compound and the amine compound is first mixed at 50°C-90°C to obtain a mixed solution, and then a mixture B comprising the lithium salt is added to the mixed solution to obtain a low eutectic solution; the quaternary ammonium salt compound and the amine compound can be stirred and mixed at, for example, 50°C, 60°C, 70°C, 80°C or 90°C; heating within a certain range can promote the dissolution of the lithium salt in the low eutectic solution.

[0069] In some embodiments of the present disclosure, in S1, the molar ratio of the quaternary ammonium salt compound, the amine compound and the lithium salt is 1:(0.5-5):(0.1-2).

[0070] In some preferred embodiments of the present disclosure, in S2,

[0071] First, immerse the positive electrode sheet of the lithium battery in the low eutectic solution, and connect the positive electrode sheet of the lithium battery to the working electrode of the main repair equipment;

[0072] At room temperature, the main repair device is discharged, and after the voltage is constant, it is maintained for 5-10 hours to obtain a positive electrode sheet after electrochemical treatment;

[0073] The positive electrode sheet after the electrochemical treatment is taken out, washed and dried to obtain the positive electrode sheet after lithium supplementation.

[0074] In some embodiments of the present disclosure, the main repair device is selected from a charging and discharging device, a voltage and current stabilizing device, or an electrochemical workstation.

[0075] In some preferred embodiments of the present disclosure, the primary repair device is selected from an electrochemical workstation.

[0076] In some embodiments of the present disclosure, in S2, the discharge current of the primary repair device is less than or equal to 5 mA.

[0077] In some embodiments of the present disclosure, the positive electrode sheet of the waste lithium battery includes a positive electrode active material, and the positive electrode active material includes one or more of lithium transition metal oxides, olivine-structured lithium-containing phosphates and their respective modified compounds.

[0078] In some embodiments of the present disclosure, the lithium transition metal oxide is selected from the general formula Li a Ni x Co y M z O 2One or more of the lithium transition metal oxides, wherein M includes at least one of Mn, Al, Mg, Cr, Ca, Zr, Mo, Ag, and Nb, 0.9≤a≤1.1, 0≤x<1, and 0≤y≤1.

[0079] In some embodiments of the present disclosure, the olivine-structured lithium-containing phosphate is selected from the general formula LiM x Fe 1- x PO 4 At least one of the lithium-containing phosphates.

[0080] Lithium battery:

[0081] In some embodiments of the present disclosure, a lithium battery is provided, which includes a positive electrode and a negative electrode, the positive electrode includes a positive electrode sheet, the positive electrode sheet includes a positive electrode collector and a positive electrode active material layer arranged on the positive electrode collector, and the positive electrode active material layer includes the aforementioned repaired lithium battery positive electrode material.

[0082] The present disclosure is further described below in conjunction with the examples. It should be understood that these examples are only used to illustrate the present disclosure and are not used to limit the scope of the present disclosure.

[0083] Example:

[0084] Test method:

[0085] ICP element test:

[0086] Place a certain amount of sample in a digestion container, add acid solution (such as hydrochloric acid, nitric acid or sulfuric acid), seal it, and heat digest it in a microwave digester or oven. After the digestion is completed, transfer the digestion solution to a volumetric flask, perform the volume adjustment and shake steps; use ICP-OES (inductively coupled plasma emission spectrometer) equipment to test the trace element content of the digestion solution.

[0087] Charge and discharge test:

[0088] In an argon-filled glove box, the positive electrode sheet, negative electrode lithium sheet and Cellgard 2400 polypropylene film were assembled into a 2032 button cell, and then the electrochemical performance of the cell was tested at a constant temperature of 25°C. The cell was charged and discharged twice at a C / 5 rate in the voltage range of 2.7-4.25V, and then cycled at a 1C rate.

[0089] Embodiment 1:

[0090] Embodiment 1 is divided into the following steps:

[0091] 1. Disassemble the positive electrode sheet: First, discharge the waste ternary lithium-ion battery, and then disassemble the waste ternary lithium-ion battery into three parts, namely ① shell and diaphragm, etc.; ② positive electrode sheet of the waste lithium battery and ③ negative electrode sheet of the waste lithium battery; among them, ① shell and diaphragm, etc. and ③ negative electrode sheet of the waste lithium battery are recycled and processed by other means, and the positive electrode sheet of ② waste lithium battery is selected, in which the positive active material of the positive electrode sheet is NCM523.

[0092] 2. Preparation of eutectic solution DES: 400 g of choline chloride and 340 g of urea were mixed and stirred at 80°C for about 30 minutes. After the liquid became clear, 35 g of lithium chloride was added and stirred for 10 hours. After all the lithium chloride was dissolved, the preparation of the eutectic solution of lithium chloride was completed.

[0093] 3. Electrochemical lithium replenishment and calcination process: Take 100 g of the positive electrode sheet of the waste lithium battery of ②, connect it to the working electrode (WE) of the electrochemical workstation, and immerse it in the aforementioned low eutectic solution DES, wherein the counter electrode (CE) is a graphite carbon electrode, and the reference electrode (RE) is an Ag / AgCl electrode, such as Figure 1 As shown; Under room temperature conditions, the electrochemical workstation starts to discharge at a current of 0.2 mA. After the voltage drops to a platform (6-8 hours), Figure 2 As shown, the electrode sheet is taken out, washed with ethanol and then vacuum dried for 1 hour to obtain a lithium-replenished positive electrode sheet; the lithium-replenished positive electrode sheet is soaked with NMP to separate the lithium-replenished positive electrode material, the lithium-replenished positive electrode material is filtered and dried, and then heated at 800°C in a muffle furnace for 3 hours to obtain the repaired positive electrode material.

[0094] 4. Preparation process of lithium battery: The repaired positive electrode material, carbon black conductive agent (SP) and binder polyvinylidene fluoride (PVDF) are mixed in a weight ratio of 8:1:1, and then 120% of the weight of the mixture is added as N-methylpyrrolidone (NMP) as a solvent, mixed, and made into a 2024 button battery. The charging specific capacity is tested to be 190.4mAh / g, and the discharge specific capacity is 161.1mAh / g.

[0095] Embodiment 2:

[0096] The steps of Example 2 are the same as those of Example 1, except that the positive electrode material in the positive electrode sheet of the selected waste lithium battery is NCM111.

[0097] Embodiment 3:

[0098] The steps of Example 3 are the same as those of Example 1, except that the eutectic solution DES used has a ratio of: 400 g of choline chloride, 340 g of urea and 3.5 g of lithium chloride.

[0099] Embodiment 4:

[0100] The steps of Example 4 are the same as those of Example 1, except that the discharge current of the electrochemical workstation is 0.05 mA when lithium is replenished.

[0101] Comparative Example 1:

[0102] Take 100g of retired NCM523 positive electrode sheet of ternary lithium-ion battery, immerse it in NMP solvent for ultrasonic cleaning to separate the active material from the current collector, and obtain the positive electrode waste black powder after centrifugal drying. According to the amount of lithium supplement measured by ICP, add an appropriate amount of lithium carbonate to the black powder for uniform mixing, put it in a muffle furnace and sinter it at 900℃ in air atmosphere for 12 hours to obtain the repaired positive electrode powder material.

[0103] ICP element test:

[0104] The ICP element tests of the repaired positive electrode materials obtained in Example 1-x and Comparative Example 1 are shown in Table 1:

[0105] [Table 1]

[0106]

[0107] Electrochemical testing:

[0108] The electrochemical tests of the repaired positive electrode materials obtained in Examples 1-4 and Comparative Example 1 are shown in Table 2:

[0109] [Table 2]

[0110]

[0111]

[0112] It can be seen that the use of low eutectic solution as a lithium replenishment solvent medium and the use of electrochemical energy for precise driving can effectively realize the lithium replenishment and repair of waste positive electrode materials at the electrode level. Combined with the subsequent short sintering process, its electrochemical properties can be efficiently regenerated to achieve characteristics matching those of commercial new materials. Compared with other lithium replenishment methods, this solution can more accurately control energy consumption and costs, and avoid ICP element quantitative detection based on the adaptive characteristics of the material structure. In addition, the use of low eutectic solutions can effectively circumvent the sensitivity of ternary materials to moisture. Low eutectic solutions can be fully degraded, reducing wastewater discharge and environmental protection costs, and are an ideal recycling solution.

[0113] Although illustrative embodiments have been shown and described, those skilled in the art should understand that the above embodiments should not be construed as limitations on the present disclosure, and that changes, substitutions and modifications may be made to the embodiments without departing from the spirit, principles and scope of the present disclosure.

Claims

1. A method for repairing a positive electrode material of a lithium battery, characterized in that: The repair method comprises S1: mixing raw materials including a quaternary ammonium salt compound, an amine compound and a lithium salt to prepare a eutectic solution; S2: immersing the positive electrode sheet of the lithium battery in the eutectic solution and performing electrochemical treatment to obtain a positive electrode sheet after lithium supplementation; S3: separating the lithium-replenished positive electrode sheet to obtain a lithium-replenished positive electrode material, and then calcining the lithium-replenished positive electrode material to obtain a repaired positive electrode material.

2. The repair method according to claim 1, wherein: In S1, a mixture A including the quaternary ammonium salt compound and the amine compound is first mixed at 50° C.-90° C. to obtain a mixed solution, and then a mixture B including the lithium salt is added to the mixed solution to obtain the low eutectic solution.

3. The repair method according to claim 2, wherein: In S1, the molar ratio of the quaternary ammonium salt compound, the amine compound and the lithium salt is 1:(0.5-5):(0.1-2).

4. The repair method according to claim 1, wherein: The quaternary ammonium salt compound comprises at least one of choline chloride, choline acetate and acetylcholine; and / or The amine compound includes at least one of urea, ethanolamine and triethanolamine; and / or The lithium salt includes at least one of lithium chloride, lithium bromide, lithium iodide, lithium hydroxide, lithium nitrate, lithium carbonate and lithium perchlorate.

5. The repair method according to claim 1, wherein: In S2, First, immerse the positive electrode sheet of the lithium battery in the low eutectic solution, and connect the positive electrode sheet of the lithium battery to the working electrode of the main repair equipment; At room temperature, the main repair device is discharged, and after the voltage is constant, it is maintained for 5-10 hours to obtain a positive electrode sheet after electrochemical treatment; The positive electrode sheet after the electrochemical treatment is taken out, washed and dried to obtain the positive electrode sheet after lithium supplementation.

6. The repair method according to claim 4, wherein: In S2, the main repair device is selected from one of a charging and discharging device, a voltage and current stabilizing device or an electrochemical workstation.

7. The repair method according to claim 4, wherein: In S2, the discharge current of the main repair device is less than or equal to 5 mA.

8. The repair method according to claim 1, wherein: In S3, Using an organic solvent to wash the positive electrode sheet after lithium supplementation to separate the positive electrode material after lithium supplementation; The lithium-supplemented positive electrode material is filtered and dried, and then calcined at 700° C.-1000° C. for 2-5 hours to obtain the repaired positive electrode material.

9. The repair method according to claim 1, wherein: The positive electrode sheet of the lithium battery includes a positive electrode material, and the positive electrode active material includes one or more of lithium transition metal oxides, lithium-containing phosphates with an olivine structure, and their respective modified compounds; Furthermore, the lithium transition metal oxide is selected from the general formula Li a Ni x Co y M z One or more of lithium transition metal oxides of O2, wherein M comprises at least one of Mn, Al, Mg, Cr, Ca, Zr, Mo, Ag, and Nb, 0.9≤a≤1.1, 0≤x<1, 0≤y≤1; The lithium-containing phosphate of the olivine structure is selected from the general formula LiM x Fe 1-x At least one of the lithium-containing phosphates of PO4.

10. A positive electrode material for a lithium battery, characterized in that: Obtained by the repair method according to any one of claims 1 to 8.

11. A lithium battery, characterized in that: The invention comprises a positive electrode sheet and a negative electrode sheet, wherein the positive electrode sheet comprises a positive electrode collector and a positive electrode active material layer arranged on the positive electrode collector, and the positive electrode active material layer comprises the positive electrode material of the lithium battery according to claim 9.

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