Organic lithium supplement agent, preparation method thereof and application of organic lithium supplement agent in positive electrode material

Abstract

The invention provides an organic lithium supplement agent, which has the following structure: # imgabs0 #, in which R1 is selected from-COOLi,-O-COOLi,-NH-COOLi and-C = C-Li, R2 is selected from H, halogen, C1-3 alkyl and C1-3 alkoxy, n is 3 or 4, and m + n = 5. The organic lithium supplement agent provided by the invention has high specific capacity and low lithium removal voltage, the specific capacity of the organic lithium supplement agent is 450mAh / g or above, the lithium removal voltage is lower than 4.7 V, the organic lithium supplement agent is obviously superior to a conventional organic lithium supplement agent, and after the organic lithium supplement agent is applied to a battery, the energy density of the lithium battery can be increased by 5mAh / g at most.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and in particular to an organic lithium supplement agent, a preparation method thereof, and application thereof in positive electrode materials. Background Art

[0002] In today's rapid development of the energy sector, lithium-ion batteries have become an indispensable key component due to their excellent performance and are widely used in many important fields such as electric vehicles, consumer electronics, and large-scale energy storage. However, as the performance requirements for lithium-ion batteries continue to rise, problems such as capacity decay 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 came into being, mainly including two methods: negative electrode lithium replenishment and positive electrode lithium replenishment. There are many means for negative electrode lithium replenishment, such as physical lithium replenishment (lithium powder, lithium metal), chemical lithium replenishment (n-butyl lithium) and electrochemical lithium replenishment (in situ electrochemical lithium replenishment and non-in situ electrochemical lithium replenishment). 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 is detrimental to the environment and human health, and the complex operation and high cost of electrochemical lithium replenishment, which limit their wide application. In contrast, positive electrode lithium replenishment shows certain advantages. Usually, a small amount of positive electrode lithium replenisher is added during the homogenization process of the positive electrode sheet preparation. During charging, lithium ions are released from the high-capacity material to replenish the irreversible capacity loss of the first charge and discharge.

[0004] At present, common positive electrode lithium replenishment 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. Although Li5FeO4 has a high theoretical specific capacity, it has solid residues after lithium replenishment, which reduces the battery energy density. Although binary lithium compounds have good lithium replenishment effects, they have gas production problems, resulting in capacity attenuation and safety hazards, and the partial delithiation potential is high, which causes serious decomposition of the electrolyte.

[0005] In this context, organic lithium supplements have gradually attracted attention. Organic lithium supplements have unique advantages. Their molecular structure has high adjustability, and the lithium supplement performance can be precisely controlled by designing functional groups and chemical bonds. For example, organic lithium supplements with specific structures can release lithium ions under relatively mild conditions, reducing the risks brought by violent reactions. In terms of cost, the raw materials of organic lithium supplements are relatively easy to obtain, and the synthesis process is relatively simple, which helps to reduce production costs. Moreover, organic lithium supplements have good compatibility with existing battery manufacturing processes and can be better integrated into positive electrode materials and electrolytes to improve the overall performance and stability of the battery. However, organic lithium supplements still need to be improved in terms of specific capacity, conductivity, chemical stability, etc., which requires further research and optimization.

[0006] CN109616629A discloses an organic lithium supplement. In the examples, only the lithium supplement containing a nitro group was studied, and the initial charge and discharge efficiency of the battery was tested. The specific capacity of the organic lithium supplement and the improvement of the battery performance were not mentioned.

[0007] Although organic lithium supplements currently have some shortcomings, they are expected to become an important development direction in the future lithium-ion battery field due to their unique advantages and potential. Through continuous research and innovation to solve the current problems, organic lithium supplements 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 of the invention

[0008] The purpose of the present invention is to solve at least one of the following technical problems existing in the existing organic lithium supplement:

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

[0010] (2) Poor air stability, easy to decompose in air;

[0011] (3) Continuous gas generation during use can easily cause battery safety hazards;

[0012] (4) The delithiation potential is high. For example, the delithiation voltage of the conventional organic lithium supplement lithium oxalate is 4.7 V.

[0013] (5) When used in batteries, the battery's cycle performance and capacity density are insufficient.

[0014] To this end, the present application provides an organic lithium supplement agent, whose specific capacity is higher than 450 mAh / g and whose lithium desorption voltage is lower than 4.7 V. Specifically, the organic lithium supplement agent provided by the present application has the following structure:

[0015] Wherein, R1 is selected from -COOLi, -O-COOLi, -NH-COOLi, -C≡C-Li, and R2 is selected from H, halogen, C 1～3 Alkyl, C 1～3 Alkoxy, n is 3 or 4, m+n=5.

[0016] Preferably, R1 is selected from -COOLi, -O-COOLi, and -NH-COOLi.

[0017] Compared with -C≡C-Li, -COOLi, -O-COOLi and -NH-COOLi are all groups with strong electron donation. Due to their electron donation effect, the electron cloud density on the benzene ring will increase, and then the electron cloud density on the hydroxy lithium (-OLi) will also increase, the binding force between lithium ions and oxygen atoms will be weakened, and the delithiation potential will be reduced. However, the electron donation ability of the three is different, which is related to the strength of the electron donation conjugation effect of the group. On the other hand,

[0018] The introduction of O or N atoms 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 insertion and extraction, 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. Therefore, R1 is preferably -COOLi.

[0019] Preferably, n=3. Too much hydroxy lithium on the benzene ring will lead to serious steric hindrance. Each hydroxy lithium 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. In addition, too much hydroxy lithium will increase the intermolecular force, and the crystallinity of the material may increase, causing the diffusion path of lithium ions in the material to become longer and more tortuous, increasing the resistance to lithium ion diffusion, which is not conducive to the rapid deintercalation of lithium ions during the charge and discharge process, thereby reducing the rate performance of the battery and the actual available delithiation capacity.

[0020] Preferably, R2 is selected from H, halogen, C 1～3 Alkyl, C 1～3 Alkoxy.

[0021] Compared with halogens, alkyl and alkoxy groups are electron-donating groups. They will increase the electron cloud density on the benzene ring, and then the electron cloud density of the lithium hydroxyl connected to the benzene ring will also increase relatively. After the electron cloud density increases, the binding force between lithium ions and oxygen atoms will weaken. During the delithiation process, lithium ions are more likely to be removed from lithium hydroxyl, thereby reducing the delithiation potential. The halogen atoms have a large electronegativity and have an electron-withdrawing inductive effect, which will reduce the electron cloud density on the benzene ring.

[0022] Furthermore, if the vacancy on the benzene ring is replaced, the substituent will occupy a certain space on the benzene ring, which will have a certain hindering effect on the diffusion of lithium ions, making it impossible for lithium ions to be completely removed, which will reduce the lithium removal capacity and increase the lithium removal voltage. Secondly, after the vacancy on the benzene ring is replaced, the relative molecular mass of the structure increases, and even if the lithium ions are completely deintercalated, its specific capacity will be reduced relative to that without substitution. Therefore, R2 is preferably H.

[0023] Preferably, m is 2. When m=2 and n=3, steric hindrance caused by excessive amount of lithium hydroxylate can be avoided.

[0024] In a specific embodiment of the present application, the organic lithium supplement has at least one of the following structures:

[0025]

[0026]

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

[0028] The precursor and the lithium source are dissolved in an organic solvent respectively, mixed and reacted, and filtered and dried after the reaction is completed to obtain the above-mentioned organic lithium supplement, wherein the precursor has the following structure:

[0029] Wherein R'1 is selected from -COOH, -O-COOH, -NH-COOH, -C≡CH, R2 is selected from H, halogen, C 1～3 Alkyl, C 1～3 Alkoxy,

[0030] n is 3 or 4, 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 reagents (such as tert-butyl lithium, n-butyl lithium, biphenyl lithium, naphthalene lithium), and the like.

[0032] Among them, the precursor is selected according to the pre-synthesized organic lithium supplement agent, such as 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-trihydroxyphenoxycarboxylic acid, 3,4,5-trihydroxyphenylacetylene lithium, etc.

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

[0034] Wherein, the reaction time is 6 to 24 hours; the drying is vacuum drying for 6 to 24 hours, and the drying temperature is 60 to 150°C.

[0035] In a third aspect, the present application provides an application of the above-mentioned organic lithium supplement agent in a positive electrode material of a lithium battery.

[0036] When the organic lithium supplement agent of the present application is used in the positive electrode material, due to its high specific capacity and low delithiation voltage, the energy density of the lithium battery can be increased by up to 5 mAh / g. In addition, the product after delithiation can be dissolved in the electrolyte and will not affect the positive electrode active material. The irreversible delithiation degree is high, and the gas produced can be discharged once during the formation process, and there will be no continuous gas production to cause battery safety problems.

[0037] In a fourth aspect, the present application provides a positive electrode material for a lithium battery, the positive electrode material comprising: the above-mentioned organic lithium supplement, a positive electrode active material, a conductive agent and a binder.

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

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

[0040] In a specific embodiment of the present application, the conductive agent can be selected from 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, in the positive electrode material, the mass content of the conductive agent is 5-10%.

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

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

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] (1) The organic lithium supplement provided by the present application has a sheet structure. The two-dimensional planar characteristics of the sheet structure are conducive to the diffusion and transmission of substances. In the battery electrode, charged particles such as lithium ions can migrate more quickly within the plane of the sheet material, thereby improving the charging and discharging speed and efficiency of the battery;

[0046] (2) The organic lithium supplement provided by the present application has a high specific capacity and a low lithium desorption voltage. The specific capacity of the lithium supplement provided by the present application is above 450 mAh / g, and the lithium desorption voltage is lower than 4.7 V, which can increase the energy density of lithium batteries by up to 5 mAh / g.

[0047] (3) The organic lithium supplement provided by the present application has a simple synthesis process, a high reaction yield, is not easy to decompose after being placed in the air for 1 month, and has stable performance; and the product of the organic lithium supplement after lithium removal is soluble in the electrolyte and will not affect the positive electrode active material;

[0048] (4) The organic lithium supplement provided in the present application has a high degree of irreversible lithium desorption, and the gas produced can be discharged once during the formation process, and will not continue to produce gas to cause battery safety problems. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a scanning electron microscope image of the organic lithium supplement agent in Example 1;

[0050] Figure 2 This is a test diagram of the electrical properties of the organic lithium supplement in Example 1;

[0051] Figure 3 is the hydrogen nuclear magnetic resonance spectrum of the organic lithium supplement agent in Example 1;

[0052] Figure 4 This is a test diagram of the electrical properties of the organic lithium supplement in Comparative Example 1. DETAILED DESCRIPTION

[0053] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0054] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0055] In the description of the present invention, the terms "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also 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 comprising the element.

[0056] In this application, when the name of a compound is inconsistent with the corresponding structural formula, the structural formula shall prevail.

[0057] The present invention is further described in detail below through specific embodiments.

[0058] Example 1

[0059] Synthesis of organic lithium supplement: weigh lithium hydroxide and 2,4,6-trihydroxybenzoic acid in a molar ratio of 4:1.

[0060] The two substances were dispersed in 60 mL of ethanol respectively, and the two substances were uniformly mixed and stirred at a stirring speed of 500 rpm for 12 h. The obtained turbid liquid was filtered, and the filter cake was vacuum dried at 110 ° C for 12 h. After natural cooling, it was ground to obtain lithiated 2,4,6-trihydroxylithium benzoate (Formula 1).

[0061] Figure 1 This is a scanning electron microscope image of 2,4,6-trihydroxylithium benzoate in Example 1.

[0062] Figure 2 This is the electrical performance test diagram of 2,4,6-trihydroxylithium benzoate in Example 1. It can be seen from the figure that the specific capacity of the lithium supplement is 547 mAh / g and the average lithium desorption voltage is 4.35 V.

[0063] Figure 3 This is the hydrogen nuclear magnetic resonance spectrum of 2,4,6-trihydroxylithium benzoate in Example 1.

[0064] The synthesis of the organic lithium supplement in Examples 2 to 4 is based on that in Example 1.

[0065] Example 5

[0066] Synthesis of organic lithium supplement: weigh lithium hydroxide and 2,4,6-trihydroxyphenoxycarboxylic acid in a molar ratio of 4:1. The two substances were dispersed in 60 mL of ethanol respectively, and the two substances were uniformly mixed and stirred at a stirring speed of 500 rpm for 24 h. The obtained turbid liquid was filtered, and the filter cake was vacuum dried at 110 ° C for 12 h. After natural cooling, it was ground to obtain lithiated 2,4,6-trihydroxylithium phenoxy formate (Formula 7).

[0067] Example 6

[0068] Synthesis of organic lithium supplement: weigh lithium hydroxide and 2,4,6-trihydroxyphenylcarbamic acid in a molar ratio of 4:1. The two substances were dispersed in 60 mL of ethanol respectively, and the two substances were uniformly mixed and stirred at a stirring speed of 500 rpm for 24 h. The obtained turbid liquid was filtered, and the filter cake was vacuum dried at 110 ° C for 12 h. After natural cooling, it was ground to obtain lithiated lithium 2,4,6-trihydroxyphenylcarbamate (Formula 9).

[0069] Example 7

[0070] Synthesis of organic lithium supplement: weigh lithium hydroxide and 2,4,6-trihydroxyphenylacetylene lithium in a molar ratio of 3:1 The two substances were dispersed in 60 mL of ethanol respectively, and the two substances were uniformly mixed and stirred at a stirring speed of 500 rpm for 24 h. The obtained turbid liquid was filtered, and the filter cake was vacuum dried at 110 ° C for 12 h. After natural cooling, it was ground to obtain lithiated 2,4,6-trihydroxylithium phenylacetylene lithium (Formula 11).

[0071] Example 8

[0072] Synthesis of organic lithium supplement: weigh lithium hydroxide and 2,3,4,6-tetrahydroxybenzoic acid in a molar ratio of 5:1. The two substances were dispersed separately in 80 mL of ethanol, mixed evenly and stirred at a speed of 500 rpm for 24 h. The obtained turbid liquid was filtered, and the filter cake was vacuum dried at 110 ° C for 12 h. After natural cooling, it was ground to obtain lithiated 2,3,4,,5-tetrahydroxylithium benzoate (Formula 14).

[0073] Example 9

[0074] Synthesis of organic lithium supplement: weigh lithium hydroxide and 3-fluoro-2,4,6-trihydroxybenzoic acid in a molar ratio of 4:1. The two substances were dispersed in 60 mL of ethanol respectively, and the two substances were evenly mixed and stirred at a stirring speed of 500 rpm for 12 h. The obtained turbid liquid was filtered, and the filter cake was vacuum dried at 110 ° C for 12 h. After natural cooling, it was ground to obtain lithiated 3-fluoro-2,4,6-trihydroxylithium benzoate (Formula 17).

[0075] The synthesis of the organic lithium supplement in Examples 10-11 refers to Example 9.

[0076] The structures of the organic lithium supplement agents in the examples and comparative examples are shown in Table 1, and the specific capacity, average lithium desorption voltage and air stability tests were performed on them respectively.

[0077] (1) Specific capacity test: The organic lithium supplement, PVDF and conductive agent SP to be tested are dissolved in the solvent NMP at a mass ratio of 90:5:5, mixed and stirred to make a slurry, and then the slurry is evenly coated on the positive electrode current collector aluminum foil, and the positive electrode sheet is obtained after drying. The positive electrode sheet and the lithium sheet are assembled into a button half-cell. The button half-cell is properly installed on the fixture of the battery test system, and is charged at a constant current of 0.1C to a voltage of 4.5V. After standing for 15 minutes, it is discharged at a constant current of 0.1C to 2.0V, and the charge specific capacity is recorded.

[0078] (2) Average lithium stripping voltage test: The organic lithium supplement to be tested, PVDF and conductive agent SP are dissolved in the solvent NMP at a mass ratio of 90:5:5, mixed and stirred evenly to form a slurry, and then the slurry is evenly coated on the positive electrode current collector aluminum foil. After drying, the positive electrode sheet is obtained. The positive electrode sheet and the lithium sheet are assembled into a button battery half-cell, and the button battery test system is used for testing. The average lithium stripping voltage is read on the test software.

[0079] (3) Air stability test: First, the organic lithium supplement, PVDF and conductive agent SP to be tested are mixed in a mass ratio of 90:5:5, and the positive electrode material sample is placed in a specific air environment. After 30 days of exposure, the sample is weighed again, the weight difference is calculated, and the air stability of the material is evaluated based on the weight change. Then, the organic lithium supplement before and after air exposure is prepared into pole pieces and assembled into batteries, and charge and discharge tests are performed respectively. The air stability is further judged based on the capacity change and charge and discharge efficiency.

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

[0081]

[0082]

[0083]

[0084] It can be seen from Table 1 that the specific capacity of the organic lithium supplement provided by the present application is above 450 mAh / g, and the lithium desorption voltage is below 4.7 V. Compared with the organic lithium supplement in the prior art, the specific capacity and lithium desorption voltage performance are improved; and the organic lithium supplement provided by the present application has good stability and no secondary gas production, while in the comparative example, the carboxyl group is easily oxidized, so the stability is poor, and the amine group and the thiol group are also unstable.

[0085] Preparation of batteries

[0086] After LiFePO4, the organic lithium supplement agent in the above embodiments and comparative examples, SP and PVDF are mixed evenly in a mass ratio of 88:5:3:4, the positive electrode sheet is obtained by slurry mixing, coating, drying and rolling. After artificial graphite, SP, sodium carboxymethyl cellulose CMC and polystyrene butadiene SBR are mixed evenly in a mass ratio of 94.4:2:2:1.6, the negative electrode sheet is obtained by slurry mixing, coating, drying and rolling. After assembling the positive and negative electrode sheets, a lithium-ion battery is obtained, and lithium supplementation of the negative electrode material is achieved in the first charge and discharge cycle. The battery is then 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. Perform charge and discharge tests on the soft-pack battery after primary formation, and collect the generated gas into a gas collection bag through a pipeline; b. Inject the collected gas into a gas chromatograph for analysis to obtain the composition and content of the gas; c. Calculate the gas production of the soft-pack battery based on the composition and content of the gas and the volume of the container.

[0088] (5) Cycle performance test: After the lithium ion battery is formed, it is charged and discharged once in an environment of 25°C. After being discharged, it is charged at a constant current of 1C to a voltage of 3.65V. After that, it is charged at a constant voltage of 3.65V with a cut-off current of 0.05C. After standing for 15 minutes, it is discharged at a constant current of 1C to 2.0V. The discharge capacity of the first cycle is recorded as C1. Then, 1000 charge and discharge cycles are performed, and the discharge capacity of the 1000th cycle is recorded as C1000. C1000 / C1×100% is recorded as the discharge capacity retention rate of the battery cell after 1000 cycles.

[0089] (6) Battery capacity density improvement test: refer to the preparation method of the above-mentioned battery, except that no organic lithium supplement is added. After the battery is formed, it is charged and discharged once in an environment of 25°C. After constant current charging at a charging current of 1C to a voltage of 3.65V, the charging cut-off current is 0.05C at a constant voltage of 3.65V. After standing for 15 minutes, it is discharged at a constant current of 1C to 2.0V. The discharge capacity of the first cycle is recorded as C2. In the cycle performance test, the discharge capacity of the first cycle is recorded as C1. The capacity density improvement ΔV = C1-C2.

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

[0091]

[0092]

[0093]

[0094] It can be seen from Table 2 that compared with not adding a lithium supplement, the organic lithium supplement provided in the present application can increase the capacity density of lithium batteries by up to 5 mAh / g and the cycle performance by up to 220%, which is significantly better than the comparative example.

[0095] The specific embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0096] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0097] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

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

2. A method for preparing the organic lithium supplement agent according to claim 1, characterized in that: include: The precursor and the lithium source are dissolved in an organic solvent respectively, mixed and reacted, and filtered and dried after the reaction is completed to obtain the organic lithium supplement, wherein the precursor has the following structure: Wherein R'1 is selected from -COOH, -O-COOH, -NH-COOH, -C≡CH, R2 is selected from H, halogen, C 1～3 Alkyl, C 1～3 Alkoxy, 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, metallic lithium, lithium hydride, tert-butyl lithium, n-butyl lithium, 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. Use 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 positive electrode materials for lithium batteries.

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

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

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

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