UV-photopolymerized cellulose acetate-acrylate membranes for lithium-ion battery separator

Cellulose acetate (CA) is attractive for use as a separator in lithium-ion batteries (LIBs). However, the dissolubility in the liquid electrolyte limits its applications. Herein, we would report a cellulose acetate (CA) cross-linked film for the separator of lithium-ion battery. First, methacrylate modified cellulose acetate (M-CA) was prepared by esterification between CA and methylacryloyl chloride. Subsequently, an insoluble polymer membrane was obtained through the UV-induced polymerization of M-CA, poly(ethylene glycol) methyl ether methacrylate (PEGMEMA) and trihydroxymethylpropyl trimethylacrylaye (TMPTMA). The results show that these polymer membranes have good thermal and chemical stability due to the cross-linked polymer matrix. When the amount of TMPTMA is 20% of the molar amount of PEGMEMA, not only has the obtained gel polymer electrolyte (GPE) a suitable ionic conductivity of 4.17 mS cm−1 and an excellent lithium ion transfer number of 0.80, but also it has discharge capacity of the half battery composed of LiFePO4/GPE/Li 120 mAh g−1 at 2 C. This study demonstrated a great possibility that the high-performance and biodegradable GPE could be applied in LIBs. In addition, there are many other methacrylate monomers that can be polymerized with M-CA to prepare various GPEs, which will open a new avenue for the application of CA in GPEs.