Electrolyte additives refer to substances with relatively small amounts that can significantly improve one or several performance of batteries. They are generally divided into flame retardant additives, anti overcharging additives, film forming additives, electrolyte stabilizers, and other additives. Among them, film forming additives generally select compounds with high reduction decomposition potential, which can decompose before other solvent components of the electrolyte during the first charge and discharge, forming a stable SEI layer on the surface of the negative electrode (solid electrolyte interface facial mask, which is an electronic insulator but an excellent conductor of Li+, through which Li+can be freely embedded and detached), thus protecting the electrode from the damage of solvent molecules and improving battery life and safety.

Lithium battery separators can be divided into dry process separators and wet process separators based on production processes, with wet membrane coating in the wet process separators being the main trend. Wet and dry methods have their own advantages and disadvantages. The wet process has a small and uniform pore size of the film, and the film is thinner. However, the investment is large, the process is complex, and the environmental pollution is high. The dry process is relatively simple, has high added value, and is environmentally friendly, but the pore size and porosity are difficult to control, making it difficult to thin the product.