An organic lithium supplementing agent, a preparation method thereof and application thereof in a positive electrode material

Abstract

The application provides an organic lithium supplementing agent, which has the following structure: wherein R1 is selected from -COOLi, -O-COOLi, -NH-COOLi and -C=C-Li; R2 is selected from H, halogen, C 1～3 alkyl, C 1～3 alkoxy, n is 3 or 4, and m+n=5. The organic lithium supplementing agent provided by the application has high specific capacity and low delithiation voltage, the specific capacity is higher than 450 mAh / g, and the delithiation voltage is lower than 4.7 V, which is obviously superior to conventional organic lithium supplementing agents. When the organic lithium supplementing agent is applied to a battery, the energy density of the lithium battery can be increased by 5 mAh / g at most.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium batteries, in particular to an organic lithium supplementing agent, a preparation method thereof and application thereof in a positive electrode material. BACKGROUND

[0002] In the rapid development of today's energy field, lithium ion batteries have become an indispensable key component due to their excellent performance, and are widely used in electric vehicles, consumer electronics and large-scale energy storage and many other important fields. However, with the continuous rise of the performance requirements of lithium ion batteries, problems such as capacity attenuation and limited cycle life have gradually become prominent, becoming a bottleneck that needs to be broken through.

[0003] In order to overcome these difficulties, pre-lithiation technology has emerged, mainly including two ways of negative electrode lithium supplement and positive electrode lithium supplement. Negative electrode lithium supplement adopts various means such as physical lithium supplement (lithium powder, lithium metal), chemical lithium supplement (n-butyl lithium) and electrochemical lithium supplement (in-situ electrochemical lithium supplement and non-in-situ electrochemical lithium supplement). However, these methods have many serious problems, such as the high chemical activity of lithium powder and lithium metal, which brings great safety risks, the strong toxicity of n-butyl lithium, which is harmful to the environment and human health, and the complex operation and high cost of electrochemical lithium supplement, which all limit its wide application. In contrast, positive electrode lithium supplement shows certain advantages, usually a small amount of positive electrode lithium supplement is added in the homogenate process of the preparation of the positive electrode sheet, and lithium ions are released from the high-capacity material during charging to supplement the irreversible capacity loss of the first charge and discharge.

[0004] The current common positive electrode lithium supplement methods include lithium-rich compounds (such as Li2NiO2, Li5FeO4), binary lithium compounds (such as Li3N, Li2O2 and Li2O), etc. However, these methods all have their own defects. Lithium-rich compounds, such as Li2NiO2, are easy to decompose and have poor air stability, while Li5FeO4 has a high theoretical specific capacity, but has solid residues after lithium supplement, reducing the energy density of the battery. Binary lithium compounds have good lithium supplement effect but have gas production problems, leading to capacity attenuation and safety hazards, and some have high delithiation potential, causing serious electrolyte decomposition.

[0005] In this context, organic lithium supplementing agents have gradually attracted attention. Organic lithium supplementing agents have unique advantages. Their molecular structures have high adjustability, allowing precise control of lithium supplementing performance through the design of functional groups and chemical bonds. For example, organic lithium supplementing agents with specific structures can release lithium ions under relatively mild conditions, reducing the risk of violent reactions. In terms of cost, the raw materials for organic lithium supplementing agents are relatively easy to obtain, and the synthesis process is relatively simple, which helps to reduce production costs. Moreover, organic lithium supplementing agents have good compatibility with existing battery manufacturing processes, and can be well integrated into positive electrode materials and electrolytes, improving the overall performance and stability of the battery. However, organic lithium supplementing agents still need to be improved in terms of specific capacity, electrical conductivity, and chemical stability, and further research and optimization are needed.

[0006] CN109616629A discloses an organic lithium supplementing agent. In the examples, only lithium supplementing agents containing nitro groups are studied, and the first charge-discharge efficiency of the battery is tested. The specific capacity of the organic lithium supplementing agent and the improvement range of the battery performance are not mentioned.

[0007] Although there are some deficiencies in organic lithium supplementing agents at present, they have unique advantages and potential and are expected to become an important development direction in the field of lithium ion batteries in the future. Through continuous research and innovation, current problems can be solved, and organic lithium supplementing agents are expected to bring new breakthroughs in improving the performance of lithium ion batteries and promote the further development of lithium ion battery technology. SUMMARY

[0008] The present application aims to solve at least one of the following technical problems of existing organic lithium supplementing agents:

[0009] (1) The specific capacity is generally not high, less than 400 mAh / g;

[0010] (2) Poor air stability, easily decomposed in air;

[0011] (3) Continuous gas production during use, which can easily cause safety hazards to the battery;

[0012] (4) High delithiation potential, for example, the delithiation voltage of conventional organic lithium supplementing agent lithium oxalate is 4.7 V;

[0013] (5) When applied in batteries, the cycle performance and capacity density of the battery are not enough.

[0014] Therefore, the present application provides an organic lithium supplementing agent with a specific capacity higher than 450 mAh / g and a delithiation voltage lower than 4.7 V. Specifically, the organic lithium supplementing agent provided by the present application has the following structure:

[0015] wherein R1is selected from -COOLi, -O-COOLi, -NH-COOLi, -C=C-Li, R2is selected from H, halogen, C 1～3 alkyl, C 1～3 alkoxy, n is 3 or 4, and m+n=5.

[0016] Preferably, R1is selected from -COOLi, -O-COOLi, -NH-COOLi.

[0017] Compared with -C=C-Li, -COOLi, -O-COOLi and -NH-COOLi are all strong electron-donating groups, due to their electron-donating effect, which will increase the electron cloud density on the benzene ring, and in turn increase the electron cloud density on the lithium hydroxide (-OLi), weaken the binding force between lithium ion and oxygen atom, and reduce the delithiation potential. However, the electron-donating abilities of the three groups are different, which is related to the strength of the electron-donating conjugation effect of the groups. On the other hand,

[0018] The introduction of O or N atom in -O-COOLi and -NH-COOLi not only increases the relative molecular mass, but also increases the steric hindrance of the molecular structure. In the process of lithium deintercalation, the larger steric hindrance will hinder the diffusion and migration of lithium ions, so that lithium ions need to overcome a larger energy barrier to be extracted from the lithium supplement agent. Therefore, R1is preferably -COOLi.

[0019] Preferably, n=3. Too many lithium hydroxide groups on the benzene ring will cause serious steric hindrance. Each lithium hydroxide group occupies a certain space, and they form a crowded structure around the benzene ring. In the process of lithium ion deintercalation, this steric hindrance will hinder the diffusion channel of lithium ions, making it difficult for lithium ions to diffuse from the inside of the material to the surface, or from the surface to the electrolyte. And too many lithium hydroxide groups will increase the intermolecular force, and the crystallinity of the material may be improved, which will make the diffusion path of lithium ions in the material longer and more tortuous, increase the resistance of lithium ion diffusion, and is not conducive to the rapid deintercalation of lithium ions in the charging and discharging process, thereby reducing the rate performance of the battery and the actual available delithiation capacity.

[0020] Preferably, R2is selected from H, halogen, C 1～3 alkyl, C 1～3 alkoxy.

[0021] Compared with halogen, alkyl and alkoxy are electron-donating groups, which will increase the electron cloud density on the benzene ring, and in turn relatively increase the electron cloud density of the lithium hydroxide connected to the benzene ring. After the electron cloud density increases, the binding force between lithium ion and oxygen atom will weaken, and lithium ion is more likely to be extracted from lithium hydroxide in the delithiation process, thereby reducing the delithiation potential. However, halogen atom has a large electronegativity, has an electron-withdrawing inductive effect, and will reduce the electron cloud density on the benzene ring.

[0022] Further, if the space on the benzene ring is substituted, the substituent will occupy a certain space on the benzene ring, which will hinder the diffusion of lithium ions, so that the lithium ions cannot be completely deintercalated, which will reduce the deintercalation capacity and increase the deintercalation voltage. Secondly, after the space on the benzene ring is substituted, the relative molecular mass of the structure increases, so that even if the lithium ions are completely deintercalated, the specific capacity will also be reduced compared with the non-substituted. Therefore, R2 is preferably H.

[0023] Preferably, m is 2. When m = 2, n = 3, the steric hindrance caused by excessive hydroxyl groups can be avoided.

[0024] In the specific embodiments of the present application, the organic lithium supplementing agent has at least one of the structures as shown below:

[0025]

[0026]

[0027] In a second aspect, the organic lithium supplementing agent can be prepared by the following method, and the specific steps include:

[0028] The precursor and the lithium source are dissolved in an organic solvent respectively, mixed and then reacted, and after the reaction is completed, filtration and drying are performed to obtain the above-mentioned organic lithium supplementing agent. The precursor has the structure as shown below:

[0029] R'1 is selected from -COOH, -O-COOH, -NH-COOH and -C≡CH, R2 is selected from H, halogen, C 1～3 alkyl, C 1～3 alkoxy,

[0030] n is 3 or 4, and m+n = 5.

[0031] The lithium source includes but is not limited to lithium carbonate, lithium bicarbonate, lithium hydroxide, metallic lithium, lithium hydride, organic Li reagent (such as tert-butyllithium, n-butyllithium, diphenyl lithium, naphthalene lithium) and the like.

[0032] The precursor is selected according to the pre-synthesized organic lithium supplementing agent, for example, 2,4,6-trihydroxybenzoic acid, 3,4,5-trihydroxybenzoic acid, 2,3,6-trihydroxybenzoic acid, 2,3,5-trihydroxybenzoic acid, 2-fluoro-3,4,5-trihydroxybenzoic acid, 2-methyl-3,4,5-trihydroxybenzoic acid, 2,3,4,5-tetrahydroxybenzoic acid, 3,4,5-trihydroxyphenoxyformic acid, 3,4,5-trihydroxyphenylacetylene lithium and the like.

[0033] The organic solvent is at least one of methanol, ethanol, tetrahydrofuran, and N,N-dimethylformamide.

[0034] The reaction time is 6-24 hours, and the drying is vacuum drying for 6-24 hours at a drying temperature of 60-150 DEG C.

[0035] In a third aspect, the application provides application of the organic lithium supplementing agent in a lithium battery cathode material.

[0036] When the organic lithium supplementing agent is applied in the cathode material, the energy density of the lithium battery can be increased by 5 mAh / g due to the high specific capacity and low delithiation voltage of the organic lithium supplementing agent, and the product after delithiation is soluble in the electrolyte, does not affect the cathode active material, has high irreversible delithiation degree, and the gas generated in the formation process can be discharged at one time and does not continuously generate gas to cause battery safety problems.

[0037] In a fourth aspect, the application provides a lithium battery cathode material, which comprises the organic lithium supplementing agent, a cathode active material, a conductive agent, and a binder.

[0038] In the embodiment of the application, the mass content of the organic lithium supplementing agent in the cathode material is 2-20%, preferably 2-5%. For example, the mass content of the organic lithium supplementing agent is 2%, 5%, 6%, 8%, 10%, 12%, 14%, 15%, 18%, 20%, or any value between 2% and 20%.

[0039] In the embodiment of the application, the cathode active material can be selected from at least one of the commonly used lithium cathode materials in the art, including but not limited to at least one of a lithium iron phosphate material or a carbon-coated lithium iron phosphate material, a lithium nickel cobalt manganese oxide ternary material or a lithium nickel cobalt manganese oxide ternary material modified by doping and coating, a lithium manganese iron phosphate material, a lithium cobaltate material, and a lithium manganate material.

[0040] In the embodiment of the application, the conductive agent can be selected from at least one of the commonly used conductive agents in the art, including but not limited to at least one of super-conductive carbon black, Ketjen black, acetylene black, single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene, and graphene oxide.

[0041] Preferably, the mass content of the conductive agent in the cathode material is 5-10%.

[0042] In the embodiment of the application, the binder can be selected from at least one of the commonly used binders in the art, including but not limited to at least one of polyvinylpyrrolidone, polyvinylidene fluoride, polyethylene oxide, polytetrafluoroethylene, sodium carboxymethyl cellulose, and a copolymer of styrene and butadiene.

[0043] Preferably, the mass content of the binder in the positive electrode material is 5-10%.

[0044] Compared with the prior art, the application has the beneficial effects that:

[0045] (1) The organic lithium supplementing agent provided by the application has a sheet structure, and the two-dimensional plane characteristics of the sheet structure are beneficial to the diffusion and transmission of substances. In a battery electrode, charged particles such as lithium ions can migrate more quickly in the plane of the sheet material, thereby improving the charge and discharge speed and efficiency of the battery.

[0046] (2) The organic lithium supplementing agent provided by the application has high specific capacity and low delithiation voltage. The specific capacity of the lithium supplementing agent is above 450 mAh / g, and the delithiation voltage is below 4.7 V. The highest energy density of a lithium battery can be improved by 5 mAh / g.

[0047] (3) The synthesis process of the organic lithium supplementing agent provided by the application is simple, the reaction yield is high, the organic lithium supplementing agent is not easy to decompose in air for 1 month, and the performance is stable. The product after delithiation of the organic lithium supplementing agent is soluble in electrolyte, and does not affect the positive active material.

[0048] (4) The organic lithium supplementing agent provided by the application has high irreversible delithiation degree, and the gas is discharged at one time in the formation process, and subsequent continuous gas production does not cause battery safety problems. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figure 1 It is a scanning electron microscope graph of the organic lithium supplementing agent in Example 1.

[0050] Figure 2 It is an electrical performance test graph of the organic lithium supplementing agent in Example 1.

[0051] Figure 3 It is a nuclear magnetic resonance hydrogen spectrum graph of the organic lithium supplementing agent in Example 1.

[0052] Figure 4 It is an electrical performance test graph of the organic lithium supplementing agent in Comparative Example 1. DETAILED DESCRIPTION

[0053] In order to make the technical problems, technical solutions and beneficial effects of the application clearer, the application will be further described in detail below in combination with examples. It should be understood that the specific examples described herein are only used to explain the application and do not limit the application.

[0054] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The endpoints of the ranges are generally provided in connection with another term or phrase, for example, "from 1 to 5" is understood to mean from 1 to 5, but also including the endpoints of the range, i.e., 1 and 5. For numeric values, the endpoints of the ranges, the endpoints of the ranges and individual point values, and individual point values can be combined with each other to form one or more new numeric ranges, which should be considered as being specifically disclosed herein.

[0055] In this description and in the claims, the terms "including", "containing", or any other similar term are intended to be non-exclusive and inclusive in meaning unless expressly indicated to the contrary.

[0056] In this application, when the compound name is not consistent with the corresponding structural formula, the structural formula is used as the standard.

[0057] The application will be further described in detail below through specific examples.

[0058] Example 1

[0059] Synthesis of organic lithium supplementing agent: Lithium hydroxide and 2,4,6-trihydroxybenzoic acid were weighed in a molar ratio of 4:1

[0060] The two substances were uniformly mixed and stirred in 60 mL of ethanol, the stirring speed was 500 rpm, and the stirring time was 12 h; the obtained turbid liquid was suction filtered, and the filter cake was vacuum dried at 110°C for 12 h, and then ground after natural cooling to obtain lithiumated 2,4,6-trihydroxybenzoic acid lithium (Formula 1).

[0061] Figure 1 It is a scanning electron microscope image of 2,4,6-trihydroxybenzoic acid lithium in Example 1.

[0062] Figure 2 It is an electrical performance test chart of 2,4,6-trihydroxybenzoic acid lithium in Example 1, from which it can be seen that the specific capacity of the lithium supplementing agent is 547 mAh / g, and the average delithiation voltage is 4.35 V.

[0063] Figure 3 It is a hydrogen nuclear magnetic resonance spectrum chart of 2,4,6-trihydroxybenzoic acid lithium in Example 1.

[0064] The synthesis of the organic lithium supplementing agent in Examples 2-4 refers to Example 1. The synthesis of the organic lithium supplementing agent in Examples 2-4 refers to Example 1.

[0065] Example 5

[0066] Synthesis of organic lithiating agent: Lithium hydroxide and 2,4,6- trihydroxyphenoxyformic acid were weighed in a molar ratio of 4:1 Each was dispersed in 60 mL of ethanol, the two substances were mixed homogeneously and stirred at a stirring speed of 500 rpm for 24 h; the turbid solution obtained was suction filtered and the filter cake was vacuum dried at 110 °C for 12 h, ground after natural cooling to obtain lithiated 2,4,6-trihydroxy lithium phenoxyformate lithium (formula 7).

[0067] Example 6

[0068] Synthesis of organic lithiating agent: Lithium hydroxide and 2,4,6- trihydroxyphenoxyformic acid were weighed in a molar ratio of 4:1 Each was dispersed in 60 mL of ethanol, the two substances were mixed homogeneously and stirred at a stirring speed of 500 rpm for 24 h; the turbid solution obtained was suction filtered and the filter cake was vacuum dried at 110 °C for 12 h, ground after natural cooling to obtain lithiated 2,4,6-trihydroxy lithium phenoxyformate lithium (formula 7).

[0069] Example 7

[0070] Synthesis of organic lithiating agent: Lithium hydroxide and 2,4,6- trihydroxyphenoxyformic acid were weighed in a molar ratio of 4:1 Each was dispersed in 60 mL of ethanol, the two substances were mixed homogeneously and stirred at a stirring speed of 500 rpm for 24 h; the turbid solution obtained was suction filtered and the filter cake was vacuum dried at 110 °C for 12 h, ground after natural cooling to obtain lithiated 2,4,6-trihydroxy lithium phenoxyformate lithium (formula 7).

[0071] Example 8

[0072] Synthesis of organic lithiating agent: Lithium hydroxide and 2,4,6- trihydroxyphenoxyformic acid were weighed in a molar ratio of 4:1 Each was dispersed in 60 mL of ethanol, the two substances were mixed homogeneously and stirred at a stirring speed of 500 rpm for 24 h; the turbid solution obtained was suction filtered and the filter cake was vacuum dried at 110 °C for 12 h, ground after natural cooling to obtain lithiated 2,4,6-trihydroxy lithium phenoxyformate lithium (formula 7).

[0073] Example 9

[0074] Synthesis of organic lithiating agent: Lithium hydroxide and 2,4,6- trihydroxyphenoxyformic acid were weighed in a molar ratio of 4:1 The two substances were uniformly mixed and stirred in 60 mL of ethanol, the stirring speed was 500 rpm, and the stirring time was 12 h; the obtained turbid liquid was suction filtered, and the filter cake was vacuum dried at 110 °C for 12 h, ground after natural cooling to obtain lithiumated 3-fluoro-2,4,6-trihydroxy lithium benzoate lithium (formula 17).

[0075] The synthesis of the organic lithium supplementing agent in examples 10-11 refers to example 9.

[0076] The structures of the organic lithium supplementing agents in the examples and comparative examples are shown in Table 1, and the specific capacity, average delithiation voltage and air stability of each were tested.

[0077] (1) Specific capacity test: the organic lithium supplementing agent to be tested, PVDF and conductive agent SP were dissolved in solvent NMP at a mass ratio of 90:5:5, uniformly mixed and stirred to prepare a slurry, then the slurry was uniformly coated on the positive electrode current collector aluminum foil, and the positive electrode sheet was obtained after drying, and the positive electrode sheet was assembled with lithium sheet to form a half battery. The half battery was correctly installed on the clamp of the battery test system, and charged at a constant current of 0.1C to a voltage of 4.5V, and then discharged at a constant current of 0.1C to 2.0V after standing for 15 min, and the charging specific capacity was recorded.

[0078] (2) Average delithiation voltage test: the organic lithium supplementing agent to be tested, PVDF and conductive agent SP were dissolved in solvent NMP at a mass ratio of 90:5:5, uniformly mixed and stirred to prepare a slurry, then the slurry was uniformly coated on the positive electrode current collector aluminum foil, and the positive electrode sheet was obtained after drying, and the positive electrode sheet was assembled with lithium sheet to form a half battery, and the average delithiation voltage was read on the test software by using the half battery test system.

[0079] (3) Air stability test: first, the organic lithium supplementing agent to be tested, PVDF and conductive agent SP were mixed at a mass ratio of 90:5:5, and the positive electrode material sample was placed in a specific air environment, and after 30 days of exposure, the sample was weighed again, the weight difference was calculated, and the air stability of the material was evaluated according to the size of the weight change. Then, the organic lithium supplementing agent before and after air exposure was prepared into an electrode sheet and assembled into a battery, and the charge-discharge test was carried out, and the air stability was further judged according to the capacity change and the charge-discharge efficiency.

[0080] Table 1: Performance test results of organic lithium supplementing agents

[0081]

[0082]

[0083]

[0084] As can be seen from Table 1, the specific capacity of the organic lithium supplementing agent provided in the present application is above 450 mAh / g, and the delithiation voltage is all below 4.7 V, compared with the organic lithium supplementing agent in the prior art, the specific capacity and delithiation voltage performance are both improved; and the organic lithium supplementing agent provided in the present application has good stability and no secondary gas production, while in the comparative examples, the carboxyl group is easily oxidized, so the stability is poor, and the amine group and the mercapto group are also unstable.

[0085] Preparation of the battery

[0086] LiFePO4, the organic lithium supplementing agent in the above examples and comparative examples, SP and PVDF were mixed in a mass ratio of 88:5:3:4, respectively, and uniformly mixed, and then slurry was adjusted, coated, dried, and rolled to obtain a positive electrode sheet. Artificial graphite, SP, sodium carboxymethyl cellulose CMC and polystyrene butadiene SBR were mixed in a mass ratio of 94.4:2:2:1.6, respectively, and uniformly mixed, and then slurry was adjusted, coated, dried, and rolled to obtain a negative electrode sheet. After assembling the positive and negative electrode sheets, a lithium ion battery was obtained, and the lithium supplementing of the negative electrode material was realized in the first charge and discharge cycle. Then, the battery was tested for gas production, capacity density improvement and cycle performance improvement, and the results are shown in Table 2 below.

[0087] (4) Battery gas production test: a, the soft package battery after the first formation was subjected to charge and discharge test, and the generated gas was collected into a gas collection bag through a pipeline; b, the collected gas was injected into a gas chromatograph for analysis to obtain the composition and content of the gas; c, according to the composition and content of the gas, and the volume of the container, the gas production of the soft package battery was calculated.

[0088] (5) Cycle performance test: after the lithium ion battery was formed, it was discharged at 25℃, and then subjected to one charge and discharge, and after constant current charging to 3.65V at 1C, constant voltage charging was carried out at 3.65V with a cutoff current of 0.05C, and after standing for 15 min, constant current discharge was carried out at 1C to 2.0V, and the discharge capacity of the first cycle was recorded as C1; then 1000 cycles of charge and discharge were carried out, and the discharge capacity of the 1000th cycle C1000 was recorded, and C1000 / C1x100% was recorded as the discharge capacity retention rate of the battery after 1000 cycles.

[0089] (6) Battery capacity density promotion test: refer to the preparation method of the battery described above, the difference is that no organic lithium supplement is added, after the battery is formed, in the environment of 25℃, after discharging, once charging and discharging, after constant current charging to 3.65V under 1C charging current, constant voltage charging is carried out at 3.65V, the cutoff current is 0.05C, after 15min, constant current discharging is carried out at 1C discharging current to 2.0V, record the discharge capacity of the first cycle as C2, record the discharge capacity of the first cycle in the cycle performance test as C1, the capacity density promotion amount ΔV=C1-C2.

[0090] Table 2: Influence of organic lithium supplement on battery performance

[0091]

[0092]

[0093]

[0094] From Table 2, compared with no lithium supplement, the organic lithium supplement provided by the application can improve the capacity density of lithium battery by 5mAh / g at most, and the cycle performance can be improved by 220% at most, which is obviously better than the comparative examples.

[0095] The above describes the specific embodiments of the application, but the application is not limited to the specific details in the above embodiments, within the technical concept of the application, various simple modifications can be made to the technical solutions of the application, and these simple modifications all belong to the protection scope of the application.

[0096] In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction, in order to avoid unnecessary repetition, the application will not further describe various possible combinations.

[0097] In addition, various different embodiments of the application can also be combined in any manner, as long as it does not deviate from the idea of the application, it should also be considered as disclosed by the application.

Claims

1. An organic lithium supplement, characterized in that, It has the following structure: R1 is selected from -COOLi, -O-COOLi, -NH-COOLi, and -C≡C-Li. R2 is selected from H, halogens, and C. 1～3 Alkyl, C 1～3 Alkoxy When n is 3 or 4, m + n = 5.

2. A method for preparing the organic lithium supplement according to claim 1, characterized in that, include: The precursor and lithium source are dissolved separately in an organic solvent, mixed, and then reacted. After the reaction is complete, the mixture is filtered and dried to obtain the organic lithium supplement. The precursor has the following structure: Where R'1 is selected from -COOH, -O-COOH, -NH-COOH, and -C≡CH. R2 is selected from H, halogens, and C. 1～3 Alkyl, C 1～3 Alkoxy When n is 3 or 4, m + n = 5.

3. The preparation method according to claim 2, characterized in that, The lithium source is at least one of lithium carbonate, lithium bicarbonate, lithium hydroxide, lithium metal, lithium hydride, tert-butyllithium, n-butyllithium, biphenyl lithium, and naphthalene lithium.

4. The preparation method according to claim 2, characterized in that, The organic solvent is at least one of methanol, ethanol, tetrahydrofuran, and N,N-dimethylformamide.

5. The application of the organic lithium supplement agent according to claim 1 or the organic lithium supplement agent obtained by the preparation method according to any one of claims 2 to 4 in the cathode material of lithium battery.

6. A lithium battery cathode material, comprising an organic lithium supplement, a cathode active material, a conductive agent, and a binder, characterized in that, The organic lithium supplement is the organic lithium supplement as described in claim 1 or the organic lithium supplement obtained by the preparation method described in any one of claims 2 to 4.

7. The cathode material according to claim 6, characterized in that, In the cathode material, the mass content of the organic lithium supplement is 2-20%.

8. The positive electrode material according to claim 6, characterized in that, In the cathode material, the cathode active material is at least one of lithium iron phosphate material or carbon-coated lithium iron phosphate material, lithium nickel cobalt manganese oxide ternary material or doped and modified lithium nickel cobalt manganese oxide ternary material, lithium manganese iron phosphate material, lithium cobalt oxide, and lithium manganese oxide material.

9. The cathode material according to claim 6, characterized in that, In the positive electrode material, the conductive agent is at least one of super conductive carbon black, Ketjen black, acetylene black, single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene, and graphene oxide.

10. The cathode material according to claim 6, characterized in that, In the positive electrode material, the binder is at least one of polyvinylpyrrolidone, polyvinylidene fluoride, polyethylene oxide, polytetrafluoroethylene, sodium carboxymethyl cellulose, and a copolymer of styrene and butadiene.

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