Cellulose acetate‐based separators prepared by a reversible acetylation process for high‐performance lithium‐ion batteries

Lithium‐ion batteries (LIBs) are one of the most widely used technologies for various applications. However, polyolefin separators can hardly meet the needs of the development of LIBs due to the poor heat shrinkage and bad wettability with the electrolyte. Herein, a cellulose acetate (CA)‐based separator is developed by blending with cellulose nanocrystals (CNCs) using a simple reversible acetylation process. This separator exhibits inherent thermal stability and improved ionic conductivity due to the finger‐like and sponge‐like porous structure. Moreover, the discharge capacity of the separator with a CNC loading of 3% remains at 132.9 mA h g−1 when the rate reverts to 0.2 C and the capacity retention reaches 89.5% after 50 cycles. Therefore, the obtained CA‐based separators can be a competitive candidate for high‐performance LIBs and point the way to sustainable development.