NbN nanodot decorated N-doped graphene as a multifunctional interlayer for high-performance lithium-sulfur batteries

The scalable applications of lithium-sulfur (Li-S) batteries are seriously hampered by the shuttling effect of lithium polysulfides (LiPSs) and the safety concern related to lithium dendrites. Herein, we report a lithiophilic and sulfiphilic NbN decorated nitrogen-doped graphene (NbN@NG) interlayer on a commercial polypropylene (PP) separator. Due to the lithiophilic features of NbN nanodots effectively hindering the growth of lithium dendrites, the Li//Li symmetric battery with NbN@NG/PP delivers outstanding stability at 5 mA h cm(-2) over 1100 h. Owing to the polar and conductive NbN nanodots with strong interaction and high catalytic conversion towards LiPSs suppressing the shuttling effect, the Li-S battery with NbN@NG/PP delivers a high discharge capacity of 1284 mA h g(-1) at 0.2C and excellent high-rate performance at 2C with a negligible capacity fading of 0.036% per cycle over 500 cycles. The Li-S pouch battery with NbN@NG/PP delivers a capacity of 847 mA h g(-1) with a low electrolyte volume/sulfur loading ratio of 6 mu L mg(-1). Theoretical density functional theory and in situ Raman spectroscopy effectively demonstrate the mechanism for LiPSs conversion. This work provides a new design strategy for multifunctional separators and new insights into the performance-enhancement mechanism towards high-performance shuttle-free and dendrite-free Li-S batteries.

Automated summary

This study presents a novel design of lithiophilic and sulfiphilic nitrogen-doped graphene decorated with niobium nitride on a commercial polypropylene separator, which effectively inhibits the growth of lithium dendrites and suppresses the shuttling effect of lithium polysulfides, leading to high performance Li-S batteries.