Method for uniformly repairing failed layered metal oxide electrode material

Abstract

The invention belongs to the field of electrochemical energy conversion and energy storage materials, and particularly relates to a method for uniformly repairing a failed layered metal oxide electrode material, which comprises the following steps: respectively mixing a lithium-containing compound, an auxiliary agent and the failed layered metal oxide electrode material in a solvent, drying the solvent by distillation, and calcining to obtain the lithium-containing layered metal oxide electrode material. And the uniformly repaired layered metal oxide electrode material is obtained. The method provided by the invention can uniformly repair the failed electrode, can solve the problem of decommissioning battery treatment to a great extent, and has a good application prospect.

Description

Technical Field

[0001] The invention belongs to the field of electrochemical energy conversion and energy storage materials, and specifically relates to a method for uniformly repairing a failed layered metal oxide electrode material. Background Art

[0002] The overall structure of failed layered metal oxide cathode materials usually remains intact, and only specific failed parts need to be repaired. Therefore, researchers have proposed the concept of direct recycling, which is to repair failed lithium battery cathode materials by supplementing missing elements and repairing the crystal structure at high temperature. Compared with traditional pyrometallurgical and wet recycling, direct recycling has high efficiency, high yield and less pollution. Direct recycling methods include hydrothermal method, molten salt method, solid phase sintering method, etc. However, these methods mainly remain at the laboratory scale and face challenges in industrial scalability. For example, the solid phase sintering method relies on mechanical mixing, which leads to uneven distribution of components, and the recovered cathode materials have poor electrochemical performance due to non-uniform repair. In order to achieve uniform repair, it is crucial to maintain consistent and continuous uniform contact between the lithium source and the failed layered metal oxide cathode particles, while the hydrothermal method and molten salt method can be achieved by additional heating or pressurization, but this will lead to complex operations and increased costs, which is difficult to promote on a large scale. Summary of the invention

[0003] In order to solve the problems of complicated operation and high cost of repairing failed electrode materials by hydrothermal method and molten salt method in the prior art, the present invention provides a method for uniformly repairing failed layered metal oxide electrode materials with simple operation:

[0004] A method for uniformly repairing a failed layered metal oxide electrode material comprises mixing a lithium-containing compound, an auxiliary agent and the failed layered metal oxide electrode material in a solvent, evaporating the solvent, and calcining to obtain a uniformly repaired layered metal oxide electrode material.

[0005] Furthermore, the mass ratio of the auxiliary agent to the layered metal oxide electrode material is 1:10-100.

[0006] Furthermore, the layered metal oxide includes one or more of ternary nickel cobalt lithium manganese oxide, ternary nickel cobalt aluminum lithium oxide, lithium cobalt oxide, lithium manganese oxide, and nickel manganese oxide.

[0007] Furthermore, the auxiliary agent includes one or more of polyvinyl pyrrolidone, dopamine, glucose, sucrose, guar gum, polyacrylic acid or polyacrylonitrile.

[0008] Furthermore, the lithium-containing compound includes one or more of lithium nitrate, lithium hydroxide, lithium chloride, lithium carbonate, lithium citrate or lithium acetate.

[0009] Furthermore, the molar ratio of the layered metal oxide electrode material to the lithium-containing compound is 100:5-85.

[0010] Furthermore, the layered metal oxide electrode material is a layered metal oxide electrode material with a failure rate of 0 to 80%.

[0011] Further, the following steps are included:

[0012] (1) adding a lithium-containing compound to ethanol or an aqueous solution to obtain a solution A;

[0013] (2) adding the additive to solution A and mixing evenly to obtain a mixed solution B;

[0014] (3) adding the failed layered metal oxide electrode material to the mixed solution B while stirring, and mixing evenly to obtain a precursor solution C;

[0015] (4) heating the precursor liquid C while stirring until it is evaporated to dryness to obtain the precursor D;

[0016] (5) The obtained precursor D is calcined in a combustion-supporting atmosphere to obtain a uniformly repaired layered metal oxide positive electrode material.

[0017] Furthermore, the temperature for heating and drying in step (4) is 80-100°C.

[0018] Furthermore, the calcination temperature in step (5) is 700-900° C., the heating rate is 3-10° C. / min, and the holding time is 4-14 h.

[0019] By adopting the above scheme, the method of the present invention has the following advantages:

[0020] 1. The present invention uses a method of sequentially mixing and evaporating solvents to uniformly diffuse lithium into failed positive electrode particles at room temperature and pressure without the need for special equipment, thereby maintaining continuous and uniform contact between the lithium source and the failed layered metal oxide positive electrode particles, creating conditions for achieving uniform repair of failed layered metal oxide positive electrode materials, significantly reducing costs, and promoting large-scale applications.

[0021] 2. The present invention uniformly supplements the missing components of the failed layered metal oxide, and after sintering, not only uniformly repairs its structure, but also restores its electrochemical properties to the original state.

[0022] 3. The auxiliary agent of the present invention has the function of dispersing and bonding, so that the lithium-containing compound is evenly formed on the surface of the failed layered metal oxide positive electrode material at room temperature and pressure. High-temperature calcination makes the lithium diffuse evenly into the positive electrode particles, and finally achieves complete and uniform repair of the entire particle.

[0023] 4. The additive of the present invention is carbonized and removed after high-temperature calcination, avoiding affecting the uniform lithium replenishment and structural repair process of the failed layered metal oxide positive electrode material. The method for repairing the electrode material is a gentle recycling process as a whole, and will not produce acidic and alkaline wastewater, which is environmentally friendly.

[0024] 5. The present invention can restore the electrochemical performance of failed layered metal oxide positive electrode materials to a state comparable to that of commercial layered metal oxide positive electrodes, thereby solving the problem of handling retired batteries to a large extent.

[0025] 6. The present invention can not only uniformly repair different failed layered metal oxide positive electrode materials, but also can achieve uniform repair of layered metal oxide positive electrode materials with different failure degrees, and has extremely high versatility. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The SEM image (a) of the non-uniformly repaired NCM523 positive electrode material prepared by the solid phase method in the comparative example and the SEM image (b) of the uniformly repaired NCM523 positive electrode material prepared in Example 1.

[0027] Figure 2 This is a TEM image of the uniformly repaired NCM523 positive electrode material prepared in Example 1.

[0028] Figure 3 This is a cycle performance diagram of the uniformly repaired NCM523 positive electrode material prepared in Example 1. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Embodiment 1:

[0031] (1) Weigh 1.25 g of LiNO 3 Dissolve in 30 mL of water and stir thoroughly until completely dissolved to obtain a mixed solution A.

[0032] (2) Weigh 0.4 g of polyvinyl pyrrolidone (PVP) and add it to mixed solution A. Stir thoroughly for 3 h to obtain mixed solution B.

[0033] (3) Weigh 4.75 g of 30% depleted NCM523 and add it to solution B. Stir thoroughly for 3 h to obtain precursor solution C.

[0034] (4) The precursor liquid C was heated and stirred at 80°C until the water was evaporated, and then placed in a vacuum drying oven for 12 hours to obtain precursor D.

[0035] (5) Precursor D was placed in a box furnace and sintered at 800°C for 10 h to obtain a uniformly repaired NCM523 positive electrode material.

[0036] Depend on Figure 2 It can be seen that clear lattice fringes can be seen on the surface of the NCM523 positive electrode material repaired by the method of the present invention, indicating that the repaired sample is well crystallized, and the atoms are tightly and evenly bonded. The lattice spacing corresponds to the (003) crystal orientation of the NCM523 positive electrode material itself, indicating that no unfused impurities are generated on the electrode material repaired by the method of the present invention, forming a uniform repair.

[0037] Figure 3 The electrode material of Example 1 was subjected to a long cycle test at 28°C. As can be seen from the figure, the repaired positive electrode material can still maintain 87.1% of the specific capacity after 200 cycles, and the coulombic efficiency has been maintained at nearly 100%. This shows that the cycle stability of the NCM523 positive electrode material repaired by the method of the present invention can reach the initial state, and the method of the present invention can restore its commercial value.

[0038] Embodiment 2:

[0039] (1) Weigh 1.25 g of LiNO 3 Dissolve in 30 mL of water and stir thoroughly until completely dissolved to obtain a mixed solution A.

[0040] (2) Weigh 0.06 g of guar gum and add it to mixed solution A. Stir thoroughly for 3 h to obtain mixed solution B.

[0041] (3) Weigh 4.75 g of 30% depleted NCM523 and add it to solution B. Stir thoroughly for 3 h to obtain precursor solution C.

[0042] (4) The precursor liquid C was heated and stirred at 80°C until the water was evaporated, and then placed in a vacuum drying oven for 12 hours to obtain precursor D.

[0043] (5) Precursor D was placed in a box furnace and sintered at 800°C for 10 h to obtain a uniformly repaired NCM523 positive electrode material.

[0044] Embodiment 3:

[0045] (1) Weigh 1.21 g of LiNO 3 Dissolve in 30 mL of water and stir thoroughly until completely dissolved to obtain a mixed solution A.

[0046] (2) Weigh 0.4 g of polyvinyl pyrrolidone (PVP) and add it to mixed solution A. Stir thoroughly for 3 h to obtain mixed solution B.

[0047] (3) Weigh 4.79 g of 30% depleted NCM811 and add it to solution B. Stir thoroughly for 3 h to obtain precursor solution C.

[0048] (4) The precursor liquid C was heated and stirred at 80°C until the water was evaporated, and then placed in a vacuum drying oven for 12 hours to obtain precursor D.

[0049] (5) Precursor D was placed in a box furnace and sintered at 700°C for 10 h to obtain a uniformly repaired NCM811 positive electrode material.

[0050] Comparative Example:

[0051] Solid phase preparation:

[0052] (1) Weigh 0.722 g of Li 2 CO 3 and 5.278 g of 30% depleted NCM523 were placed in a ball mill and ball milled to obtain mixed powder A.

[0053] (2) The mixed powder A is placed in a box furnace and sintered at 800° C. for 10 h to obtain the repaired NCM523 positive electrode material.

[0054] Depend on Figure 1 It can be seen that the surface of the NCM523 cathode material treated by the existing solid phase method in Figure a is rough, with many irregular and uneven lithium oxide particles, indicating that the uneven contact between the lithium source and the failed cathode particles by the ordinary solid phase method will lead to uneven diffusion of lithium, and the lithium source cannot be completely and evenly combined with the NCM523 cathode material to be repaired. In Figure b, the surface of the repaired NCM523 cathode material is smooth, indicating that the lithium source used for repair has been completely integrated with the NCM523 cathode material, achieving uniform repair.

[0055] For those skilled in the art, various other corresponding changes and deformations can be made according to the technical solutions and concepts described above, and all of these changes and deformations should fall within the protection scope of the claims of the present invention.

Claims

1. A method for uniformly repairing a failed layered metal oxide electrode material, characterized in that: The lithium-containing compound, the auxiliary agent and the failed layered metal oxide electrode material are mixed in a solvent respectively, and then the solvent is evaporated and calcined to obtain a uniformly repaired layered metal oxide electrode material.

2. The method for uniformly repairing a failed layered metal oxide electrode material according to claim 1, characterized in that: The mass ratio of the auxiliary agent to the layered metal oxide electrode material is 1:10-100.

3. The method for uniformly repairing a failed layered metal oxide electrode material according to claim 1, characterized in that: The layered metal oxide includes one or more of ternary nickel-cobalt-manganese lithium oxide, ternary nickel-cobalt-aluminum lithium oxide, lithium cobalt oxide, lithium manganese oxide, and nickel-manganese lithium oxide.

4. The method for uniformly repairing a failed layered metal oxide electrode material according to claim 1, characterized in that: The auxiliary agent includes one or more of polyvinyl pyrrolidone, dopamine, glucose, sucrose, guar gum, polyacrylic acid or polyacrylonitrile.

5. The method for uniformly repairing a failed layered metal oxide electrode material according to claim 1, characterized in that: The lithium-containing compound includes one or more of lithium nitrate, lithium hydroxide, lithium chloride, lithium carbonate, lithium citrate or lithium acetate.

6. The method for uniformly repairing a failed layered metal oxide electrode material according to claim 1, characterized in that: The amount ratio of the layered metal oxide electrode material to the lithium-containing compound is 100:5-85.

7. The method for uniformly repairing a failed layered metal oxide electrode material according to claim 1, characterized in that: The layered metal oxide electrode material is a layered metal oxide electrode material with a failure rate of 0 to 80%.

8. The method for uniformly repairing a failed layered metal oxide electrode material according to claim 1, characterized in that: The following steps are involved: (1) adding a lithium-containing compound to ethanol or an aqueous solution to obtain a solution A; (2) adding the additive to solution A and mixing evenly to obtain a mixed solution B; (3) adding the failed layered metal oxide electrode material to the mixed solution B while stirring, and mixing evenly to obtain a precursor solution C; (4) heating the precursor liquid C while stirring until it is evaporated to dryness to obtain the precursor D; (5) The obtained precursor D is calcined in a combustion-supporting atmosphere to obtain a uniformly repaired layered metal oxide positive electrode material.

9. The method for uniformly repairing a failed layered metal oxide electrode material according to claim 8, characterized in that: The temperature for heating and evaporating to dryness in step (4) is 80-100°C.

10. The method for uniformly repairing and doping-modifying a failed layered metal oxide positive electrode according to claim 8, characterized in that: The calcination temperature in step (5) is 700-900° C., the heating rate is 3-10° C. / min, and the insulation time is 4-14 h.

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