MXene debris modified eggshell membrane as separator for high-performance lithium-sulfur batteries

A functional separator (MXene/ESM) to suppress the lithium polysulfides shuttling via coating MXene debris on one surface of a biodegradable eggshell membrane (ESM) is designed to enhance the electrochemical performance of Li-S batteries. The excellent electronic conductivity of the porous MXene debris, and the good mechanical strength, superior thermal stability as well as large electrolyte infiltration of ESM make MXene/ESM an ideal separator for high-performance Li-S batteries. The strong chemisorption induced from both Ti-S bond formed between Ti atom in MXene and the lithium polysulfides by the Lewis acid-base interaction and affinity of O and N containing functional groups on ESM to the lithium polysulfides greatly prevents the shuttling effect of the polysulfides. Compared with a commercial polypropylene separator, the Li-S battery with the MXene/ESM separator containing a KJC/S cathode and a Li metal anode displays greatly improved cycling stability with a capacity retention of 74% after 250 cycles at 0.5 C, while the Li-S battery with a polypropylene separator remains only 11%. The rate performance of Li-S battery with the MXene/ESM separator has also been enhanced compared to that with a polypropylene separator. Specifically, the Li-S battery with the MXene/ESM separator has a discharge capacity of 1321 mAh g−1 at 0.1 C, 1112 mAh g−1 at 0.2 C, 1003 mAh g−1 at 0.5 C and 948 mAh g−1 at 1 C. © 2018