In the essential steps of the lithium-ion battery manufacturing process described above, there are five key issues to consider from material selection to post-molding capacity testing:
I. Improving the physicochemical structure of the positive and negative electrode active materials is a fundamental step in the lithium-ion battery manufacturing process:
1. Appropriately dope the material with ions.
2. Improve the particle size distribution of the active material to prevent it from becoming too wide.
3. Use materials with disordered layered structures or thinner layers whenever possible.
4. Improve the surface structure of the electrode material;
Second, the high adhesion strength of the electrode coating is beneficial in reducing the cycle capacity degradation rate. This is the most technically demanding process in lithium-ion battery manufacturing, and therefore, the following should be noted:
1. The binder and solvent used to form the adhesive material must be pure, and the coated electrode sheets should not be stored for too long.
2. The ratio of adhesive to active material used in the mixing of positive and negative electrode coatings must be appropriate to ensure that no powder falls off or detaches after coating.
III. Optimization of electrolyte composition: The requirements for electrolytes in lithium-ion battery manufacturing processes are to maintain capacity and extend battery life.
1. By optimizing lithium salts, solvents, and additives, the conductivity of the electrolyte is improved and polarization is reduced.
2. Suppress the reaction between the positive electrode material and the electrolyte.
3. By controlling the appropriate specific surface area and performing surface treatments such as coating, film formation, and surface chemical reactions on the carbon anode material, the surface structure of the anode material can be improved;
IV. After the battery materials are prepared, the lithium-ion battery production process enters the assembly stage. At this time, the following should be noted:
1. The negative electrode capacity is slightly larger than the positive electrode capacity.
2. After the positive and negative electrodes and the separator are wound, the particle size of the gap between the positive and negative electrode sheets and the separator shall not exceed 0.5 mm, and the vertical deviation shall not exceed 0.5 mm.
5. When performing capacity testing, it is advisable to use low-rate charging, generally 0.2C, in accordance with national standards.
In general, the following proportions should be emphasized during the manufacturing process: electrode surface area and electrode compaction density, negative electrode excess rate, formulation process, and appropriate amounts of electrolyte and positive and negative electrodes.
The time required for each step in the lithium-ion battery manufacturing process varies. Generally, the processes of material preparation, baking, and formation take longer, ranging from about 10 hours to as long as two days and two nights; other processes are faster, averaging 5 to 6 hours. The entire lithium-ion battery manufacturing process takes approximately 15 days.
