VN quantum dots anchored N-doped carbon nanosheets as bifunctional interlayer for high-performance lithium-metal and lithium-sulfur batteries

Abstract

Lithium dendrite growth and shuttling of lithium polysulfides (LiPSs) seriously hinder the industrialization of lithium-sulfur (Li-S) batteries. Herein, elaborately designed VN quantum dots anchored N-doped carbon nanosheets (VN@NC) is employed as a bifunctional separator. The strong absorption and catalytic conversion of polar VN quantum dots effectively suppress the shuttling effect of LiPSs, confirmed by experimental and theoretical calculations studies; moreover, lithiophilic VN@NC acts as Li-ion redistributor to regulate and redistribute the interfacial ionic flux, thus effectively inhibit the uncontrollable growth of Li dendrites. As a result, the Li-S cell with VN@NC interlayer delivers ultralong cycle life (0.036 % per cycle at 2C over 1000 cycles) and high-rate capability (752 mAh/g at 4C). Even with sulfur loading (5.4 mg cm−2) and lean electrolyte/sulfur (E/S) usage (4.6 μL mg−1), the pouch cell can deliver an initial areal capacity of 5.16 mAh cm−2 and still retain 4.02 mAh cm−2 at 0.1C over 50 cycles. The VN@NC-based Li-Li symmetric cells demonstrate great cycling and rate performance in protecting the Li anode. This work offers a bi-functionally integrated interlayer strategy to simultaneously suppress the shuttling of LiPSs and dendrite growth of Li anode for high-performance Li-S and Li-metal batteries.