Asymmetric Porous and Highly Hydrophilic Sulfonated Cellulose/Biomembrane Functioning as a Separator in a Lithium-Ion Battery

Biomembranes based on sulfonated cellulose (SC) blended with PLA/PBS composites were fabricated with different SC contents into polymer matrices. The obtained membranes were applied as separators in lithium-ion batteries (LIBs). The porosities of SC/biomembranes with 0.5, 1, and 2 wt % SC contents were estimated to be 66.6, 73.4, and 87.7%, respectively, which are significantly greater than that of the Celgard 2400 membrane, a commercial monolayer polypropylene (PP) separator membrane (42.1%). Due to its high porosity, hydrophilicity, and good interfacial compatibility with electrodes, the SC/biomembranes offer high electrolyte uptake and low interfacial resistance, leading to enhanced ionic conductivity. The cell with the 2 wt % SC/biomembrane also exhibited stable cycle performance and improved rate capacity, especially when discharged at the 0.2C rate. A 106 mAh/g capacity retention rate was achieved for a battery with the 2 wt % SC/biomembrane after 100 cycles at the 1C rate; meanwhile, the Celgard 2400 membrane exhibited a capacity of 81 mAh/g. These results show that SC has great innovative potential for use as a biofiller in biomembranes, which is suitable for LIB applications.