A Silane Cross-Linked Cellulose-Based Separator for Long-Life Lithium Metal Batteries Application

Cellulose-based separators with good electrolyte wettability and thermal stability have attracted extensive attention in the area of lithium metal battery (LMB) applications. However, their low mechanical strength in an electrolyte has seriously hindered their cycling performance of assembled LMB. Herein, a silane-crosslinked propionylated cellulose-based separator (PBF-GPTMS) was prepared. The resulting separator exhibited high wet strength (18.7 MPa) and electrolyte uptake (312 wt%). Molecular simulation revealed that Young’s modulus of the silanized propionylated cellulose model was 14.64 GPa under EC/DMC/DEC conditions, which was higher than that of the propionylated cellulose model (6.89 GPa). In particular, the XPS spectra of the Li foil in the PBF-GPTMS-assembled battery after cycling suggested a lower amount of HF formed during cycling. Accordingly, the assembled Li/Separator/LiFePO4 cell showed excellent cycle performance with capacity retention of 94.5% after 300 cycles at 0.5 C and 93.6% after 160 cycles at 1 C, respectively. This idea would provide novel insights into the design of bio-based separators for long-life LMBs.