Nitrogen-doped sheet VO2 modified separator to enhanced long-cycle performance lithium-sulfur battery
Shuttle effect is the core problem in lithium-sulfur battery, which makes internally poor dynamics and bad cycle stability of the lithium-sulfur battery (Li-S battery). In this study, a sheet nitrogen-doped vanadium dioxide material that roots in a metal-organic framework (SVO) was designed and synthesized. SVO has a unique two-dimensional structure and uniform distribution of metal sites. It leads to the adsorption-catalytic synergistic effect that can efficiently anchor polysulfides and promote sulfur conversion kinetics to significantly alleviate the shuttle effect. With the metal-organic framework precursor synthesized under mild conditions of room temperature and pressure, the SVO materials used to modify the separator can be simply obtained by calcination. Especially, the modified material exhibits excellent electrochemical performance with only 0.081% degradation of capacity per cycle at 1C after 500 cycles. Even under a harsh condition (sulfur loading = 6.3 mg cm-2, E/S = 5), the battery with SVO/AB separator is available to reach an area capacity of about 4.16 mAh cm-2 at 0.1C. Meantime, as for the anode side, SVO/AB separator can be used as lithium-ion guides to keep stable lithium-ion stripping/plating and inhibit the growth of lithium dendrite. The battery with SVO/AB separator also shows superior performance under high and low temperatures.