What are the critical methods for pre-lithiation of lithium batteries?

For a full battery, the SEI film formed at the negative electrode interface will consume the lithium ions extracted from the positive electrode and reduce the capacity of the battery; if we can find a lithium source outside the positive electrode material, let the SEI film be formed Consuming the lithium ions of the external lithium source, it can ensure that the lithium ions deintercalated from the positive electrode will not be wasted in the formation process, and finally the capacity of the lithium battery can be increased. This process of supplying external lithium sources is pre-lithiation. The critical method of pre-lithiation is lithium battery manufacturers. jpg 1. The negative electrode is formed into a method in advance to form the negative electrode separately. After the negative electrode forms the SEI film, it is assembled with the positive electrode to prevent the loss of lithium ions in the positive electrode and greatly improve the first efficiency of the whole battery. capacity. The advantage of this pre-lithiation method is that it can simulate the normalization process to the maximum, while ensuring that the formation effect of the SEI film is similar to that of lithium batteries, but the two processes of early formation of the negative electrode and the assembly of the positive and negative plates are too difficult to operate . 2. The negative electrode spraying lithium powder method produces a stable metal lithium powder particle. The inner layer of the particle is lithium metal, and the outer layer is a protective layer with good lithium ion conductivity and electronic conductivity; during the prelithiation process, The lithium powder is first dispersed in an organic solvent, and then the dispersion is sprayed on the negative electrode sheet, and then the residual organic solvent on the negative electrode sheet is dried, so that the pre-lithiated negative electrode sheet is obtained. During formation, the lithium powder sprayed on the negative electrode will be consumed in the formation of the SEI film, thereby maximizing the retention of lithium ions extracted from the positive electrode and increasing the capacity of the lithium battery. The disadvantage of using this pre-lithiation method is that it is safer It is difficult to guarantee, and the cost of material and equipment transformation is high. 3. Compared with the normal copper foil in the negative three-layer electrode method, the copper foil of the three-layer electrode method is coated with the metal lithium powder required for later formation. In order to protect the lithium powder from reacting with the air, a protective layer is coated. ; The negative electrode is painted straight on the protective layer. When the battery cell is filled with liquid, the protective layer will dissolve in the electrolyte, so that the metal lithium contacts the negative electrode, and the lithium ions consumed to form the SEI film during the formation are supplemented by the metal lithium powder. This method affects the production conditions of the lithium battery factory. There are no strict requirements, but the stability of the protective layer in the pole piece winding, rolling, cutting and other stations is a great challenge to the research and development of electrode materials. After the metal lithium powder disappears, the adhesion of the anode material is also quite guaranteed. difficult. 4. The positive electrode lithium-rich material method. When the first effect of the negative electrode is lower than that of the positive electrode, too much lithium ions will be lost to the negative electrode during formation, causing the effective space of the positive electrode to be underfilled by lithium ions after discharge, forming a positive electrode lithium-insertion space Waste: If a small amount of high-gram-capacity lithiation-rich material is added to the positive electrode, more lithium ions can be supplied for the formation of the SEI film during formation, and there is no need to worry that the lithiation-rich material will not be able to insert lithium again during discharge. Disclaimer: Some pictures and content of the articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous post: Analysis of 18650 lithium battery parameters and repair methods