Recent advances in lithium-ion battery separators with enhanced safety

Lithium-ion battery separators are correlated closely with battery safety. An increase in the energy density of batteries requires a decrease in separator thickness, whereas the thermal runaway risk and the uncontrolled devastating power of large-scale applied high-capacity lithium-ion batteries increase exponentially. Therefore enhancing the battery safety by separator design and engineering is of considerable significance. Traditional polyolefin separators are mechanically insufficient and thermally unstable. Ceramic-coated polyolefin separators and multilayered self-shutdown separators are already commercially available to partially improve the mechanical and thermal stability of battery separators. In this chapter, adjustive self-shutdown separators and ceramic-coated fibrous membranes are introduced. Mechanically and thermally stable separators with new polymers, new preparation methods, and novel structures are discussed. Studies on the correlation among the composition, structure, and mechanical and thermal properties of the developed separators are emphasized. Attention is also paid to the nonflammable design and mechanical enhancement of solid polymer electrolytes and polymer/inorganic composite solid electrolytes. In closing, the future perspective for development of separators for next-generation high-voltage, high-capacity batteries is given.