Preparation of cellulose-based lithium ion battery membrane enhanced with alkali-treated polysulfonamide fibers and cellulose nanofibers

A cellulose-based lithium ion battery (LIB) membrane fabricated with northern bleached softwood kraft pulp (NBSK), alkali-treated polysulfonamide (A-PSA) and cellulose nanofibers (CNF) have been prepared successfully. PSA fibers are firstly treated by alkali for more carboxyl and amino groups on their surface. Then A-PSA@CNF composites are formed by the adsorption of CNF on the surface of A-PSA fibers and found to possess improved electrolyte wettability and mechanical strength properties, as well as better retention and distribution of CNF in the membrane. The cellulose-based membrane is obtained from NBSK fibers and A-PSA@CNF composites via a facile paper-making process. It is found that the NBSK/A-PSA/CNF membrane shows better mechanical strength and narrower pore size distribution, higher electrolyte wettability and thermal stability compared with those of the control, thanks to the excellent properties of A-PSA@CNF composites. The testing LIB cell assembled with the prepared cellulose-based membrane shows high capacitance performance even after 100 charge/discharge cycles. The study puts forward a novel approach to modify PSA fiber with alkali treatment and following CNF adsorption, to improve its electrolyte wettability and mechanical properties during the preparation of cellulose-based separator.