Method for preparing photo-assisted lithium secondary battery composite electrode material by recycling waste lithium battery ternary material

Abstract

The invention belongs to the field of novel energy, and relates to a preparation method of a photo-assisted lithium secondary battery positive electrode material. The method is characterized in that a waste ternary battery NCM positive electrode material is used as a raw material, is directly precipitated by using an imidazole derivative after being subjected to one-step acidification, and is subjected to high-temperature calcination to form a multi-metal particle and carbon nanotube composite structure, and the composite material is used as a positive electrode to improve the performance of the photo-assisted lithium secondary battery. Ni, Co and Mn metal particles and the carbon nanotubes form a multilevel structure, and separation of photon-generated carriers is accelerated. Due to the Schottky heterojunction formed by the three kinds of metal nanoparticles, on one hand, recombination of photon-generated carriers is well avoided; on the other hand, unused hot carriers are subjected to thermal relaxation through an electron-phonon scattering process and a phonon-phonon scattering process, so that a large amount of heat is generated, charge transfer and a surface kinetic reaction are accelerated, and the ultralow temperature performance is improved through heat generated by the photothermal effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy, and particularly relates to a method for recycling ternary materials of waste lithium batteries to prepare a composite electrode material for a photo-assisted lithium secondary battery. Background Art

[0002] In recent years, due to environmental pollution and the problem that primary energy is facing exhaustion due to abuse, the demand for clean energy has been increasing day by day. In particular, the utilization and storage of solar energy have gradually attracted attention. Integrating solar energy and secondary batteries into one device is a powerful means to solve the discontinuous time and space of solar energy. Due to in-depth research on lithium secondary batteries, it has been found that the photo-effect can comprehensively optimize the performance of lithium secondary batteries, and at the same time, solar energy can be used as an external energy supplement to make up for the energy loss in energy storage. Therefore, photo-assisted lithium secondary batteries have received extensive attention and research in recent years.

[0003] Due to the development in the field of energy batteries in recent years, a large number of waste batteries have been generated. Improper treatment of waste lithium-ion batteries will bring serious environmental pollution. More importantly, waste lithium-ion batteries contain a large amount of precious metals. Therefore, effectively recycling and utilizing waste lithium-ion batteries will be beneficial to the recycling of metal resources.

[0004] The present invention uses transition metals in waste NCM cathode materials as the main body of the catalyst. Through acid leaching and then coordination molecular precipitation, a green, simple and easy-to-operate recycling process is realized. The catalyst material is directly generated by annealing. The Ni, Co, and Mn metal particles form a hierarchical structure with the annealed tubular carbon material, accelerating the separation of photo-generated carriers. The Schottky heterojunction formed by the three metal nanoparticles, on the one hand, well avoids the recombination of photo-generated carriers; on the other hand, the unused hot carriers undergo thermal relaxation through electron-phonon and phonon-phonon scattering processes, thereby generating a large amount of heat, accelerating charge transfer and surface kinetic reactions, and the heat generated by the photothermal effect realizes the improvement of ultra-low temperature performance. When applied as a cathode material in a photo-assisted lithium secondary battery, it can effectively accelerate electron conductivity and ion transport, inhibit deformation during cycling, improve the overall cycling stability of the material, and in addition, increase the utilization rate of light energy and enhance the photo-assisted effect. Summary of the Invention

[0005] The purpose of the present invention is to prepare a composite electrode material for a photo-assisted lithium secondary battery by recycling ternary materials of waste lithium batteries.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] (1) Dissolve 1 - 2 g of NCM in 20 - 50 mL of organic acids such as citric acid, malic acid or acetic acid with a concentration of 0.5 - 2 mol / L, add 2 - 5 mL of hydrogen peroxide, stir at 50 - 70 °C for 1 - 6 h, then filter and make up the volume to 200 - 500 mL to obtain the NCM leaching solution.

[0008] (2) Add 1 - 2 g of imidazole derivative to the NCM leaching solution under stirring and heating conditions, stir for 3 - 12 h, centrifuge and wash the obtained purple precipitate, and dry it overnight in an oven at 60 - 80 °C to obtain the rNCM-MOF composite material. Grind the obtained rNCM-MOF composite material carefully, and then anneal it at 300, 600, 800 and 900 °C for 90 - 120 min under argon protection respectively to obtain rNCM-MOF-300, rNCM-MOF-600, rNCM-MOF-800 and rNCM-MOF-900.

[0009] (3) Uniformly mix the prepared rNCM-MOF, rNCM-MOF-300, rNCM-MOF-600, rNCM-MOF-800 and rNCM-MOF-900 composite materials with conductive carbon black and PVDF in a mass ratio of 5 - 8:1 - 4:1, then uniformly coat them on carbon cloth, stainless steel mesh, carbon paper or titanium mesh, and vacuum dry them in an oven at 60 °C for 12 h to obtain the rNCM-MOF-n cathode material.

[0010] (4) Assemble the rNCM-MOF-n cathode material into a battery to obtain good rate performance and cycling performance, as Figure 2 shown. Description of the Drawings

[0011] Figure 1 SEM morphology diagrams and XRD diagrams of the rNCM-MOF material annealed at different temperatures.

[0012] Figure 2 TEM morphology diagram of the rNCM-MOF-800 material. Detailed Embodiments

[0013] Example 1:

[0014] Dissolve 1.1 g of NCM in 20 mL of 1 mol / L citric acid solution, add 2 mL of hydrogen peroxide, stir at 50 °C for 1 h, then filter and make up the volume to 200 mL to obtain the NCM leaching solution.

[0015] Add 1.5 g of benzimidazole to 100 mL of the NCM leaching solution under stirring and heating, stir for 12 h, centrifuge and wash the resulting purple precipitate, and dry it overnight in an oven at 60 °C to obtain the rNCM-MOF composite material. Carefully grind the obtained rNCM-MOF composite material, and then anneal it at 300, 600, 800, and 900 °C for 90 min under argon protection to obtain rNCM-MOF-300, rNCM-MOF-600, rNCM-MOF-800, and rNCM-MOF-900 respectively.

[0016] Respectively mix the prepared rNCM-MOF, rNCM-MOF-300, rNCM-MOF-600, rNCM-MOF-800, and rNCM-MOF-900 composite materials with conductive carbon black and PVDF in a mass ratio of 7:2:1, and then uniformly coat them on carbon cloth, and vacuum dry them in an oven at 60 °C for 12 h to obtain the rNCM-MOF-n cathode material.

[0017] Example 2:

[0018] Dissolve 2.2 g of NCM in 40 mL of 1 mol / L citric acid solution, add 4 mL of hydrogen peroxide, stir at 50 °C for 1 h, then filter and make up the volume to 400 mL to obtain the NCM leaching solution.

[0019] Add 1.5 g of dimethylimidazole to 100 mL of the NCM leaching solution under stirring and heating, stir for 6 h, centrifuge and wash the resulting purple precipitate, and dry it overnight in an oven at 60 °C to obtain the rNCM-MOF composite material. Carefully grind the obtained rNCM-MOF composite material, and then anneal it at 300, 600, 800, and 900 °C for 90 min under argon protection to obtain rNCM-MOF-300, rNCM-MOF-600, rNCM-MOF-800, and rNCM-MOF-900 respectively.

[0020] Respectively mix the prepared rNCM-MOF, rNCM-MOF-300, rNCM-MOF-600, rNCM-MOF-800, and rNCM-MOF-900 composite materials with conductive carbon black and PVDF in a mass ratio of 8:1:1, and then uniformly coat them on carbon cloth, and vacuum dry them in an oven at 60 °C for 12 h to obtain the rNCM-MOF-n cathode material.

[0021] Example 3:

[0022] Dissolve 1.1 g of NCM in 20 mL of 1 mol / L citric acid solution, add 2 mL of hydrogen peroxide, stir at 50 °C for 1 h, then filter and make up the volume to 200 mL to obtain the NCM leaching solution.

[0023] Add 2 g of nitroimidazole to 150 mL of the NCM leaching solution under stirring and heating, stir for 12 h, centrifuge and wash the obtained purple precipitate, and dry it overnight in an oven at 60 °C to obtain the rNCM-MOF composite material. Grind the obtained rNCM-MOF composite material carefully, and then anneal it at 300, 600, 800, and 900 °C for 90 min under argon protection to obtain rNCM-MOF-300, rNCM-MOF-600, rNCM-MOF-800, and rNCM-MOF-900.

[0024] Mix the prepared rNCM-MOF, rNCM-MOF-300, rNCM-MOF-600, rNCM-MOF-800, and rNCM-MOF-900 composite materials with conductive carbon black and PVDF uniformly at a mass ratio of 8:1:1, and then uniformly coat them on carbon cloth and vacuum dry them in an oven at 60 °C for 12 h to obtain the rNCM-MOF-n cathode materials.

[0025] Example 4:

[0026] Dissolve 2.2 g of NCM in 40 mL of 1 mol / L citric acid solution, add 4 mL of hydrogen peroxide, stir at 50 °C for 1 h, then filter and make up the volume to 400 mL to obtain the NCM leaching solution.

[0027] Add 2 g of dimethylimidazole to 200 mL of the NCM leaching solution under stirring and heating, stir for 6 h, centrifuge and wash the obtained purple precipitate, and dry it overnight in an oven at 60 °C to obtain the rNCM-MOF composite material. Grind the obtained rNCM-MOF composite material carefully, and then anneal it at 300, 600, 800, and 900 °C for 90 min under argon protection to obtain rNCM-MOF-300, rNCM-MOF-600, rNCM-MOF-800, and rNCM-MOF-900.

[0028] Mix the prepared rNCM-MOF, rNCM-MOF-300, rNCM-MOF-600, rNCM-MOF-800, and rNCM-MOF-900 composite materials with conductive carbon black and PVDF uniformly at a mass ratio of 6:3:1, and then uniformly coat them on carbon cloth and vacuum dry them in an oven at 60 °C for 12 h to obtain the rNCM-MOF-n cathode materials.

[0029] Example 5:

[0030] Dissolve 1.1 g of NCM in 20 mL of 1 mol / L citric acid solution, add 2 mL of hydrogen peroxide, stir at 50 °C for 1 h, then filter and make up the volume to 200 mL to obtain the NCM leaching solution.

[0031] Add 1 g of dimethylimidazole to 50 mL of the NCM leaching solution under stirring and heating, stir for 12 h, centrifuge and wash the obtained purple precipitate, and dry it overnight in an oven at 60 °C to obtain the rNCM-MOF composite material. Grind the obtained rNCM-MOF composite material carefully, and then anneal it at 300, 600, 800, and 900 °C for 90 min under argon protection to obtain rNCM-MOF-300, rNCM-MOF-600, rNCM-MOF-800, and rNCM-MOF-900.

[0032] Mix the prepared rNCM-MOF, rNCM-MOF-300, rNCM-MOF-600, rNCM-MOF-800, and rNCM-MOF-900 composite materials with conductive carbon black and PVDF uniformly at a mass ratio of 8:1:1, and then uniformly coat them on carbon paper and vacuum dry them in an oven at 60 °C for 12 h to obtain the rNCM-MOF-n cathode materials.

Claims

1. The preparation method of rNCM-MOF-n composite material is as follows: The preparation steps of NCM leachate are as follows: Take 1-2g NCM and dissolve it in 20-50mL, 0.5-2mol / L citric acid, malic acid or acetic acid solution, add 2-5mL hydrogen peroxide, stir at 50-70℃ for 1-6h, then filter and adjust the volume to 200-500mL to obtain NCM leachate. The preparation method of rNCM-MOF composite material is as follows: Add 1 to 2 g of imidazole derivative to the NCM leachate under stirring and heating, stir for 3 to 12 hours, centrifuge and wash the obtained purple precipitate, and dry it in an oven at 60-80°C overnight to obtain the rNCM-MOF composite material. The preparation method of rNCM-MOF-n composite material is as follows: The obtained rNCM-MOF composite material was carefully ground and then annealed at 300, 600, 800 and 900°C for 90 to 120 min under argon protection to obtain rNCM-MOF-300, rNCM-MOF-600, rNCM-MOF-800 and rNCM-MOF-900. The preparation method of rNCM-MOF-n positive electrode material is as follows: The prepared rNCM-MOF, rNCM-MOF-300, rNCM-MOF-600, rNCM-MOF-800 and rNCM-MOF-900 composite materials were uniformly mixed with conductive carbon black and PVDF in a mass ratio of 5-8:1-4:1, and then uniformly coated on carbon cloth, stainless steel mesh, carbon paper or titanium mesh, and vacuum dried in an oven at 60°C for 12 h to obtain the rNCM-MOF-n positive electrode material.

2. The method for preparing the NCM leachate according to claim 1, characterized in that Use organic acids such as citric acid, malic acid or acetic acid to achieve green recycling.

3. The method for preparing the NCM leachate according to claim 1, characterized in that Hydrogen peroxide was used as the reducing agent.

4. The method for preparing the rNCM-MOF composite material according to claim 1, characterized in that Co was used in the preparation of rNCM-MOF 2+ 、Ni 2+ , Mn 2+ It is the metal center, imidazole nitrogen is the organic ligand, and is obtained by self-assembly.

5. The method for preparing the rNCM-MOF composite material according to claim 1, characterized in that The coordination ability of imidazole nitrogen and metal ions is different, so it is necessary to select a corresponding precipitation time of 3 to 12 h and a corresponding heating temperature of 50 to 90 °C.

6. The method for preparing rNCM-MOF-n according to claim 1, characterized in that Before annealing, the rNCM-MOF-n powder needs to be carefully ground and the heating rate should be between 1 and 5 °C min -1 , so that the material can be heated evenly and a material with a relatively uniform structure can be obtained.

7. The method for preparing rNCM-MOF-n according to claim 1, characterized in that The grinding and coating method allows it to be evenly loaded on the carbon cloth, stainless steel mesh, carbon paper or titanium mesh, which is beneficial to light transmission.

8. The method for preparing rNCM-MOF-n according to claim 1, characterized in that The rNCM-MOF-n, conductive carbon black and PVDF are uniformly mixed in a mass ratio of 5 to 8:1 to 4:1.

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