Mesoporous hydroxyl vanadium oxide/nitrogen-doped graphene enabled fast polysulfide conversion kinetics for high-performance lithium-sulfur batteries

Transition metal vanadium (V)-based oxides with various morphologies have been used in lithium-sulfur (Li-S) batteries to restrain the polysulfide shuttling because of their strong chemical interaction with polysulfides and the high catalytic activity toward the polysulfide transformation. Herein, hollow vanadium oxide spheres (VOOH) with several integrated merits are prepared and used to construct an interlayer between separator and cathode. The mesopore-abundant thin shells of VOOH are beneficial for the fast ion transport. Combined with nitrogen (N)-doped graphene sheets (NG), the as-obtained VOOH/NG interlayer allows fast electron/ion transport, finally enhancing polysulfide transformation kinetics. The Li-S batteries with the VOOH/NG exhibit a high initial discharge capacity (1441.1 mAh g−1 at 0.1C), low capacity decay rate (0.075% per cycle at 1C after 600 cycles), good rate capability, and high areal discharge capacity exceeding that of commerical lithium ion batteries. In addition, the real application of such VOOH-based interlayer is further demonstrated by the successful assembly and good performance of the corresponding pouch cells.