Thermally stable poly-aromatic solid electrolyte coated polyethylene membrane as high-performance lithium-ion battery separator

Abstract

Improving the dimensional stability and electrolyte wettability of polyolefin separators is crucial to enhancing the safety and performance of power lithium-ion batteries (LIBs). In this work, composited separators that significantly improve both thermal stability and solvent wettability are prepared by coating polyaromatic solid electrolyte (sulfonated poly(aryl ether ketone), SPAEK) onto the surface of commercial polyethylene (PE) separators. Interestingly, the coating layer formed by SPAEK with a 60% sulfonation degree exhibits abundant porous structure owing to the polar sulfonic group inducing a retarded phase separation process. The polyelectrolyte coating layer enables both super-electrolyte affinity and higher electrolyte uptake of the composite separator. Moreover, the composited separator presents much better comprehensive properties, including thermal stability and ionic conductivity. As a result, the SPAEK-coated composite separator assembles LiNi0.83Co0.11Mn0.06O2 (NCM811)/Li battery exhibits a higher capacity retention rate of 84.01% at 2 C with a specific capacity of 151.25 mAh g−1 after 200 cycles. Hence, this modified separator is a potential material that facilitates high performance and safety for Li-ion batteries.