Surface functionalization of cellulose derived from hemp by tetraethyl orthosilicate (TEOS) and poly vinylidene fluoride-based composite separator membrane for lithium-ion batteries (LIBs)

Abstract

Separators played a crucial role in enhancing the electrochemical performance of lithium-ion batteries (LIBs). However, achieving separators with outstanding electrochemical performance and high stability proved to be a challenge. Herein, composite membranes based on polyvinylidene fluoride (PVDF) with variable contents of microcrystalline cellulose/tetraethyl orthosilicate (MCC/TEOS) incorporated into PVDF matrices were carefully designed. These MCC/TEOS-based PVDF separator membranes were subsequently deployed as separators in LIBs. Notably, the 3 wt% MCC/TEOS-based PVDF separator membrane exhibited a remarkable porosity of 92.3%, representing a substantial enhancement compared to the pristine PVDF membrane with a porosity of 82.5%. This heightened porosity, in conjunction with heightened hydrophilicity, endowed the PVDF membrane with 3 wt% MCC/TEOS with superior electrolyte absorption and reduced resistance, resulting in an impressive ionic conductivity of 0.5144 mS/cm. Moreover, the LIB cell employing the 3 wt% MCC/TEOS-based PVDF separator membrane consistently demonstrated stable charge/discharge profiles at a rate of 0.2C, achieving a specific capacity of 98 mAh/g, while the PVDF membrane in isolation only reached 43 mAh/g. These findings underscored the considerable potential of MCC/TEOS as a biofiller for biomembranes, rendering it an optimal choice for applications in LIBs.