Comparative Study of the Electrochemical Performance of Different Separators in Aprotic Li-O₂Batteries

Nonaqueous lithium-oxygen (Li-O2) batteries have drawn the broad attention of researchers in recent years. A separator, as an indispensable component of a battery, significantly affects the electrolyte retention rate, ion conduction, and anode stability in a Li-O2 battery. However, a comprehensive comparison and analysis of the performance of commonly used separators in Li-O2 batteries are still lacking. In this study, systematic electrochemical performances of Li-O2 batteries with five kinds of commonly used separators Celgard 2400 (hereinafter referred to as Celgard), Whatman GF/A, GF/D, GF/F, and a laboratory-made gel polymer electrolyte (GPE) were investigated. Experimental results showed that batteries with GF/D and GD/F separators had far more stable cycling performances than those with GF/A, Celgard, and GPE, although the batteries with Celgard and GPE displayed similar discharge and charge capacity to the others. A slightly better cycling performance at the current rate of 200 mA g-1 was obtained with GF/F than with GF/D. Nevertheless, considering the much higher price of GF/F than that of GF/D, the latter could be the best candidate for validating the Li-O2 battery measurement. This study provides researchers with a valuable reference for choosing suitable separators for Li-O2 batteries from the perspectives of cost and performance, which would push forward the process of the practical application of Li-O2 batteries.