Lithium oxalate lithium supplement agent, preparation method thereof, positive pole piece and lithium ion battery

Abstract

The invention relates to the technical field of lithium ion batteries, and particularly provides a lithium oxalate lithium supplement agent, a preparation method thereof, a positive pole piece and a lithium ion battery. The invention aims to solve the problem of limited improvement of a process for reducing lithium oxalate lithium removal potential by using a catalyst in the prior art. The preparation method of the lithium oxalate lithium supplement agent comprises the following steps: respectively providing powder a of lithium oxalate and powder b of a catalyst; providing a mixture c of the powder a and the powder b; and standing the mixture c at a preset temperature T and a preset pressure p for a preset time t, and then cooling to obtain the composite material. According to the method, the physical acting force between the lithium oxalate and the catalyst can be improved, the lithium removal potential of the lithium oxalate is more effectively reduced, and the gram capacity exertion of the lithium oxalate is improved, so that the lithium oxalate is better matched with the working voltage of an existing positive electrode material.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion batteries, and particularly provides a lithium oxalate lithium supplement agent, a preparation method thereof, a positive electrode sheet and a lithium-ion battery. Background Art

[0002] In recent years, with the increasing growth of the energy storage market, energy storage batteries with long life and high safety performance have attracted more and more attention. Among them, the positive electrode lithium supplement technology can effectively improve the capacity and cycle performance of the battery, and has attracted the attention of scientific researchers. The positive electrode lithium supplement material requires relatively stable cost, good processability and manufacturability. Lithium oxalate with low price has very high market application value because of its high theoretical capacity and good stability.

[0003] However, lithium oxalate also has certain disadvantages. Although the theoretical capacity of lithium oxalate is very high, its relatively high lithium deintercalation potential (>4.7V) makes it difficult to match the working voltage of existing positive electrode materials. Therefore, how to effectively reduce the lithium deintercalation potential of lithium oxalate and maximize the capacity of lithium oxalate is a technical problem that needs to be solved urgently in the industrialization process of the lithium oxalate lithium supplement agent.

[0004] At present, the following three methods are mainly used for improvement:

[0005] 1. Nanocrystallization: By methods such as recrystallization, ultrasonic evaporation drying, and freeze drying, the particle size of lithium oxalate is made nanocrystalline to shorten the ion diffusion path;

[0006] 2. Using a conductive agent: Using conductive additives such as Ketjen black, SP, and CNT to improve the electronic conductivity;

[0007] 3. Catalyst: By using catalysts such as metal oxides and metal carbides, the decomposition energy barrier of lithium oxalate is reduced, and the decomposition voltage is lowered.

[0008] However, the above methods all have certain defects. For example, the nanocrystallization manufacturing cost is high, the output is low, the improvement effect is limited and it is not conducive to mass production; the conductive agent is generally added during the mixing process, and good contact between the conductive agent and lithium oxalate and a good conductive network between particles are required. Conventionally, high specific surface area or chain-like conductive agents are used and a large amount is added, which has higher requirements for the dispersion of the slurry, and a large amount of conductive carbon reduces the proportion of the active material; and in the use of the catalyst, good contact with lithium oxalate must be ensured to better play its role in reducing the lithium deintercalation potential of lithium oxalate, but the current processing technology has limited improvement.

[0009] Correspondingly, a new technical solution is needed in this field to solve the above technical problems. Summary of the Invention

[0010] The present invention aims to solve the above technical problems, that is, to solve the problem that the process improvement of using a catalyst to reduce the de-lithiation potential of lithium oxalate in the prior art is limited.

[0011] In a first aspect, the present invention provides a method for preparing a lithium oxalate lithium supplement, wherein the preparation method includes:

[0012] Providing powder a of lithium oxalate and powder b of a catalyst respectively;

[0013] Providing a mixed material c containing powder a and powder b;

[0014] Letting the mixed material c stand at a preset temperature T and a preset pressure p for a preset time t and then cooling it to obtain the product.

[0015] In a preferred technical solution of the above preparation method, the D 50 particle size a1 of the powder a satisfies the relational expression: 0.4 μm ≤ a1 ≤ 2 μm.

[0016] In a preferred technical solution of the above preparation method, the D 50 particle size a1 of the powder a satisfies the relational expression: 0.5 μm ≤ a1 ≤ 1.8 μm.

[0017] In a preferred technical solution of the above preparation method, the D 50 particle size a1 of the powder a and the D 50 particle size b1 of the powder b satisfy the relational expression: 1 / 7 ≤ a1 / b1 ≤ 5 / 4.

[0018] In a preferred technical solution of the above preparation method, the D 50 particle size a1 of the powder a and the D 50 particle size b1 of the powder b satisfy the relational expression: 1 / 5 ≤ a1 / b1 ≤ 1.

[0019] In a preferred technical solution of the above preparation method, the preset pressure p satisfies 1000 kgf ≤ p ≤ 5000 kgf;

[0020] and / or, the preset temperature T satisfies 100 °C ≤ T ≤ 300 °C;

[0021] and / or, the preset time t satisfies 12 h ≤ t ≤ 72 h.

[0022] In a preferred technical solution of the above preparation method, the standing condition of the mixed material c is an anaerobic environment.

[0023] In a preferred technical solution of the above preparation method, both the powder a and the powder b are provided by granulation.

[0024] In a preferred technical solution of the above preparation method, the catalyst is at least one of NiO, MnO2, Co3O4, Mn3O4, and Mo2C.

[0025] In a second aspect, the present invention provides a lithium oxalate lithium supplement, wherein the lithium oxalate lithium supplement is prepared by the above preparation method.

[0026] In a third aspect, the present invention provides a positive electrode plate, wherein the positive electrode plate includes the above lithium oxalate lithium supplement.

[0027] In a fourth aspect, the present invention provides a lithium-ion battery, wherein the lithium-ion battery includes the above positive electrode plate.

[0028] The present invention has the following technical effects:

[0029] 1. The method of the present invention can improve the physical interaction between lithium oxalate and the catalyst, thereby more effectively reducing the de-lithiation potential of lithium oxalate and improving its specific capacity utilization, making it better match the working voltage of the existing positive electrode materials.

[0030] 2. The method of the present invention is simple to operate, pollution-free in the process, and low in cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. In the drawings:

[0032] Figure 1 is a process flow chart of the preparation method of the lithium oxalate lithium supplement of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principle of the present invention and are not intended to limit the protection scope of the present invention.

[0034] In this application, the term "and / or" describes the association relationship of associated objects and indicates that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. Where A and B may be singular or plural. The character " / " generally represents an "or" relationship between the associated objects before and after.

[0035] In this application, "at least one" means one or more, and "a plurality" means two or more. "At least one of the following" or its similar expressions refer to any combination of these items, including any combination of single item or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can both represent: a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively.

[0036] It should be understood that in various embodiments of this application, the magnitudes of the sequence numbers of the above - mentioned processes do not mean the order of execution. Some or all of the steps can be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of this application.

[0037] The terms used in the embodiments of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The singular forms "a", "the", and "said" used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0038] The weights of the relevant components mentioned in the specification of the embodiments of this application can not only refer to the specific contents of each component, but also represent the proportional relationship of the weights between the components. Therefore, as long as the contents of the relevant components in the specification of the embodiments of this application are scaled up or down in proportion, they are within the scope disclosed in the specification of the embodiments of this application. Specifically, the mass mentioned in the specification of the embodiments of this application can be mass units well - known in the chemical field such as μg, mg, g, kg, etc.

[0039] The terms "first" and "second" are only used for descriptive purposes to distinguish objects such as substances from each other, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. For example, without departing from the scope of the embodiments of this application, the first XX can also be called the second XX, and similarly, the second XX can also be called the first XX. Thus, the features defined with "first" and "second" can explicitly or implicitly include one or more of such features.

[0040] The experimental methods in the following embodiments are all conventional methods unless otherwise specified, and the materials, reagents, etc. used in the following embodiments can all be obtained from commercial channels unless otherwise specified.

[0041] Based on the problem that the process improvement of using a catalyst to reduce the de-lithiation potential of lithium oxalate in the prior art pointed out in the background art is limited. The present invention provides a simple and mass-producible preparation method of a lithium oxalate lithium supplement agent. By using the method of the present invention, the physical interaction force between lithium oxalate and the catalyst can be improved, thereby more effectively reducing the de-lithiation potential of lithium oxalate, enhancing its specific capacity performance, and making it better match the working voltage of the existing cathode materials.

[0042] Specifically, in the first aspect, the present invention provides a preparation method of a lithium oxalate lithium supplement agent, see Figure 1 , and the preparation method includes:

[0043] S1. Respectively provide the powder a of lithium oxalate and the powder b of the catalyst;

[0044] S2. Provide a mixed material c containing the powder a and the powder b;

[0045] S3. Let the mixed material c stand at a preset temperature T and a preset pressure p for a preset time t and then cool down to obtain the product.

[0046] The present invention prepares the lithium oxalate lithium supplement agent by mixing the powder of lithium oxalate and the powder of the catalyst, standing at a preset pressure and a preset temperature for a preset time and then cooling down, which can improve the physical interaction force between lithium oxalate and the catalyst, more effectively reduce the de-lithiation potential of lithium oxalate, enhance its specific capacity performance, and thus make it better match the working voltage of the existing cathode materials.

[0047] In some specific embodiments, the D 50 particle size a1 of the powder a satisfies the relationship: 0.4 μm ≤ a1 ≤ 2 μm.

[0048] In some preferred embodiments, the D 50 particle size a1 of the powder a satisfies the relationship: 0.5 μm ≤ a1 ≤ 1.8 μm.

[0049] In some specific embodiments, the D 50 particle size a1 of the powder a and the D 50 particle size b1 of the powder b satisfy the relationship: 1 / 7 ≤ a1 / b1 ≤ 5 / 4.

[0050] In some preferred embodiments, the D 50 particle size a1 of the powder a and the D 50 particle size b1 of the powder b satisfy the relationship: 1 / 5 ≤ a1 / b1 ≤ 1.

[0051] In the present invention, by controlling the D 50 particle size a1 of the powder a or regulating the D 50 particle size a1 of the powder a and the D 50The relationship between the particle sizes b1 can enable the de-lithiation potential and specific capacity of lithium oxalate to reach better values.

[0052] In some preferred embodiments, the D of the powder a 50 The particle size a1 satisfies the relational expression: 0.5 μm ≤ a1 ≤ 1.8 μm; and, the D of the powder a 50 The particle size a1 and the D of the powder b 50 The particle size b1 satisfy the following relational expression: 0.2 ≤ a1 / b1 ≤ 1.

[0053] In the present invention, by controlling the D of the powder a 50 The particle size a1, and regulating the relationship between the D of the powder a 50 The particle size a1 and the D of the powder b 50 The particle size b1, the de-lithiation potential and specific capacity of lithium oxalate can reach the optimal values.

[0054] In some specific embodiments, the mass percentage of the powder b in the mixed material c is 1% - 10%. For example, it can be 1%, 2%, 4%, 6%, 8%, 10% or any value within the mass percentage range.

[0055] In some specific embodiments, the preset pressure p satisfies 1000 kgf ≤ p ≤ 5000 kgf.

[0056] In the present invention, the preset pressure p is provided by a contact pressurization method, and the value of the preset pressure p can be 1000 kgf, 2000 kgf, 3000 kgf, 4000 kgf, 5000 kgf or any value within the above range.

[0057] In some specific embodiments, the preset temperature T satisfies 100°C ≤ T ≤ 300°C. Specifically, it can be 100°C, 150°C, 200°C, 250°C, 300°C or any value within the temperature range.

[0058] In some specific embodiments, the preset time t satisfies 12 h ≤ t ≤ 72 h. Specifically, it can be 12 h, 24 h, 36 h, 72 h or any value within the time range.

[0059] In some specific embodiments, the static condition of the mixed material c is an anaerobic environment.

[0060] In some specific embodiments, both the powder a and the powder b are provided by a granulation method.

[0061] It should be noted that in the present invention, no limitation is imposed on the granulation method, and any commonly used granulation method in the art can be used. For example, any one of wet or dry processes such as ball milling, sand milling, and grinding can be used.

[0062] In some specific embodiments, the powder a is obtained by ball milling and drying lithium oxalate and ethanol in a ball mill.

[0063] In some specific embodiments, the amounts of lithium oxalate and ethanol are such that the solid content is controlled at 10% - 30%.

[0064] In some specific embodiments, the powder b is obtained by ball milling and drying a catalyst and deionized water in a ball mill.

[0065] In some specific embodiments, the amounts of the catalyst and deionized water are such that the solid content is controlled at 5% - 30%.

[0066] In some specific embodiments, the temperature reduction is to room temperature.

[0067] In some specific embodiments, the catalyst is at least one of NiO, MnO₂, Co₃O₄, Mn₃O₄, Mo₂C.

[0068] In a second aspect of the present invention, a lithium oxalate lithium supplement is provided, wherein the lithium oxalate lithium supplement is prepared by the above preparation method.

[0069] In a third aspect of the present invention, a positive electrode plate is provided, wherein the positive electrode plate includes the above-mentioned lithium oxalate lithium supplement.

[0070] It can be understood that the positive electrode plate can be prepared according to conventional methods known in the art. For example, the positive electrode main material, lithium oxalate lithium supplement, conductive agent, binder, and solvent are stirred and mixed evenly in a certain proportion to obtain a positive electrode slurry, and then the positive electrode plate is obtained through coating, baking, and rolling.

[0071] In a fourth aspect of the present invention, a lithium-ion battery is provided, wherein the lithium-ion battery includes the above-mentioned positive electrode plate.

[0072] It can be understood that the battery can be prepared and used according to conventional methods known in the art.

[0073] The present invention obtains a lithium oxalate lithium supplement by mixing the powder of lithium oxalate and the powder of the catalyst, standing at a preset pressure and preset temperature for a preset time, and then reducing the temperature, and further provides a positive electrode plate and a lithium-ion battery including the lithium oxalate lithium supplement. Using this method can improve the physical interaction between lithium oxalate and the catalyst, more effectively reduce the de-lithiation potential of lithium oxalate, improve its specific capacity utilization, so that it can better match the working voltage of the existing positive electrode materials.

[0074] The following describes in detail the preparation method of the lithium oxalate lithium supplement of the present application through several specific embodiments.

[0075] Example 1

[0076] The preparation method of the lithium oxalate lithium supplement in this embodiment includes the following steps:

[0077] S1. Ball-mill and dry lithium oxalate and ethanol (with a solid content controlled at 20%) in a ball mill to obtain powder a with a particle size a1 distributed around 1 μm; ball-mill and dry the catalyst NiO and deionized water (with a solid content controlled at 20%) in a ball mill to obtain powder b with a particle size b1 distributed around 2 μm. 50 S1. Ball-mill and dry lithium oxalate and ethanol (with a solid content controlled at 20%) in a ball mill to obtain powder a with a particle size a1 distributed around 1 μm; ball-mill and dry the catalyst NiO and deionized water (with a solid content controlled at 20%) in a ball mill to obtain powder b with a particle size b1 distributed around 2 μm. 50

[0078] S2. Dry-mix and mix powder a and powder b evenly to obtain mixed material c; wherein, the mass percentage of powder b in mixed material c is 5%.

[0079] S3. Let mixed material c stand for a preset time t of 24 h under the conditions of a preset temperature T of 200 °C, anaerobic, and a preset pressure p of 4000 kgf, and then cool it to room temperature to obtain the finished lithium oxalate lithium supplement.

[0080] Example 2

[0081] The preparation method of the lithium oxalate lithium supplement in this embodiment is the same as that in Embodiment 1. The difference from Embodiment 1 is that the particle size a1 of lithium oxalate in step S1 is 50 0.5 μm.

[0082] Example 3

[0083] The preparation method of the lithium oxalate lithium supplement in this embodiment is the same as that in Embodiment 1. The difference from Embodiment 1 is that the particle size a1 of lithium oxalate in step S1 is 50 1.8 μm.

[0084] Example 4

[0085] The preparation method of the lithium oxalate lithium supplement in this embodiment is the same as that in Embodiment 1. The difference from Embodiment 1 is that the particle size a1 of lithium oxalate in step S1 is 50 0.4 μm.

[0086] Example 5

[0087] The preparation method of the lithium oxalate lithium supplement in this embodiment is the same as that in Embodiment 1. The difference from Embodiment 1 is that the particle size a1 of lithium oxalate in step S1 is 50 2 μm.

[0088] Example 6

[0089] ​The preparation method of the lithium oxalate lithium supplement in this embodiment is the same as that in Example 1. The difference from Example 1 is that in step S1, the D of NiO 50 The particle size b1 is 1 μm.

[0090] Example 7

[0091] The preparation method of the lithium oxalate lithium supplement in this embodiment is the same as that in Example 1. The difference from Example 1 is that in step S1, the D of NiO 50 The particle size b1 is 5 μm.

[0092] Example 8

[0093] The preparation method of the lithium oxalate lithium supplement in this embodiment is the same as that in Example 1. The difference from Example 1 is that in step S1, the D of NiO 50 The particle size b1 is 0.8 μm.

[0094] Example 9

[0095] The preparation method of the lithium oxalate lithium supplement in this embodiment is the same as that in Example 1. The difference from Example 1 is that in step S1, the D of NiO 50 The particle size b1 is 7 μm.

[0096] Example 10

[0097] The preparation method of the lithium oxalate lithium supplement in this embodiment is the same as that in Example 1. The difference from Example 1 is that in step S3, the preset temperature T is 100 °C, the preset pressure p is 5000 kgf, and the preset time t is 12 h.

[0098] Example 11

[0099] The preparation method of the lithium oxalate lithium supplement in this embodiment is the same as that in Example 1. The difference from Example 1 is that in step S3, the preset temperature T is 300 °C, the preset pressure p is 1000 kgf, and the preset time t is 72 h.

[0100] Example 12

[0101] The preparation method of the lithium oxalate lithium supplement in this embodiment is the same as that in Example 1. The difference from Example 1 is that in step S1, the catalyst is MnO2.

[0102] Example 13

[0103] The preparation method of the lithium oxalate lithium supplement in this embodiment is the same as that in Example 1. The difference from Example 1 is that in step S1, the catalyst is Co3O4.

[0104] Example 14

[0105] The preparation method of the lithium oxalate lithium supplement in this embodiment is the same as that in Example 1. The difference from Example 1 is that in step S1, the catalyst is Mn3O4.

[0106] Example 15

[0107] The preparation method of the lithium oxalate lithium supplement in this embodiment is the same as that in Example 1. The difference from Example 1 is that in step S1, the catalyst is Mo2C.

[0108] In each embodiment, the D 50 particle size a1 of powder a and the D 50 particle size b1 of powder b and their relationship a1 / b1 are shown in Table 1:

[0109] Table 1

[0110] Comparative Example 1

[0111] Lithium oxalate only undergoes the particle size treatment in step S1 of Example 1 and does not undergo subsequent treatment.

[0112] Test Example 1

[0113] This test example assembles button cells with the lithium oxalate lithium supplements prepared in the examples and comparative examples of the present invention and conducts performance tests on them.

[0114] Button cell assembly: Using a lithium metal sheet as the negative electrode, prepare electrode sheets with the lithium oxalate lithium supplements prepared in Examples 1 to 15 and Comparative Example 1. The method for preparing the electrode sheets is as follows: Using NMP as the solvent, mix the lithium supplement material, binder (PVDF), and conductive agent (SP) in a weight ratio of 90:5:5 in NMP, and after mixing evenly, coat it on the aluminum foil on one side. PVDF is used in the form of a glue solution, and the solid content of the glue solution is 6.05%. The thickness of the aluminum foil is 12μm, and the purity is above 99%. The electrode sheet is compacted to 2.5 g / cm 3 , and assemble it into a button half-cell in a vacuum glove box with a Celgand2325 separator. Conduct performance tests on the assembled button cells.

[0115] The test method is: Charge to 4.8V at 0.1C and discharge to 3.0V at 0.1C, and the nominal capacity is 500 mAh / g.

[0116] The results are shown in Table 2:

[0117] Table 2 Scheme Charge specific capacity at 0.1C (mAh / g) Lithium extraction potential (V) Example 1 523.1 4.29 Example 2 518.5 4.3 Example 3 513.6 4.32 Example 4 495.6 4.4 Example 5 493.7 4.41 Example 6 518.9 4.29 Example 7 515.7 4.3 Example 8 500.6 4.33 Example 9 497.4 4.36 Example 10 521.6 4.3 Example 11 522.3 4.29 Example 12 520.9 4.3 Example 13 521.6 4.29 Example 14 519.8 4.31 Example 15 520.9 4.3 Comparative Example 1 487.6 4.66

[0118] As can be seen from the results in Table 2:

[0119] For Examples 1 to 15 as compared with Comparative Example 1, the de-lithiation potential of lithium oxalate after being treated by the present invention is significantly reduced, and the specific capacity is improved.

[0120] It can be seen from Examples 1 to 9 that when controlling the D 50 particle size a1 of powder a to satisfy 0.4 μm ≤ a1 ≤ 2 μm or regulating the relationship between the D 50 particle size a1 of powder a and the D 50 particle size b1 of powder b to satisfy 1 / 7 ≤ a1 / b1 ≤ 5 / 4, the de-lithiation potential and specific capacity of lithium oxalate can reach better values than those of Comparative Example 1; when controlling the D 50 particle size a1 of powder a to satisfy 0.8 μm ≤ a1 ≤ 1.8 μm or regulating the relationship between the D 50 particle size a1 of powder a and the D 50 particle size b1 of powder b to satisfy 1 / 5 ≤ a1 / b1 ≤ 1, the de-lithiation potential and specific capacity of lithium oxalate can reach even better effects than those of Comparative Example 1. It can be seen that when simultaneously controlling the particle size of lithium oxalate and the particle size matching ratio thereof with the catalyst, the de-lithiation potential and specific capacity can reach the optimal values.

[0121] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the protection scope of the present invention.

Claims

1. A method for preparing a lithium oxalate lithium supplement, characterized in that: The preparation method comprises: Provide lithium oxalate powder a and catalyst powder b respectively; Providing a mixed material c comprising powder a and powder b; The mixed material c is placed at a preset temperature T and a preset pressure p for a preset time t and then cooled to obtain the mixed material c.

2. The preparation method according to claim 1, characterized in that: The D of the powder a 50 The particle size a1 satisfies the relationship: 0.4μm≤a1≤2μm; Preferably, the powder a has a D 50 The particle size a1 satisfies the relationship: 0.5μm≤a1≤1.8μm.

3. The preparation method according to claim 1 or 2, characterized in that: The D of the powder a 50 Particle size a1 and D of powder b 50 The particle size b1 satisfies the relationship: 17≤a1 / b1≤54; Preferably, the powder a has a D 50 Particle size a1 and D of powder b 50 The particle size b1 satisfies the relationship: 15≤a1 / b1≤1.

4. The preparation method according to claim 1, characterized in that: The preset pressure p satisfies 1000kgf≤p≤5000kgf; And / or, the preset temperature T satisfies 100°C≤T≤300°C; And / or, the preset time t satisfies 12h≤t≤72h.

5. The preparation method according to claim 4, characterized in that: The static condition of the mixture c is an oxygen-free environment.

6. The preparation method according to claim 1, characterized in that: The powder a and powder b are both provided by granulation.

7. The preparation method according to claim 1, characterized in that: The catalyst is at least one of NiO, MnO2, Co3O4, Mn3O4, and Mo2C.

8. A lithium oxalate lithium supplement, characterized in that: The lithium oxalate lithium supplement is prepared by the preparation method according to any one of claims 1 to 7.

9. A positive electrode sheet, characterized in that: The positive electrode plate includes the lithium oxalate lithium supplement agent according to claim 8.

10. A lithium ion battery, characterized in that: The lithium-ion battery comprises the positive electrode sheet according to claim 9.

Images