A compact inorganic layer for robust anode protection in lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries are one of the most promising candidates for high energy density rechargeable batteries beyond current Li-ion batteries. However, severe corrosion of Li metal anode and low Coulombic efficiency (CE) induced by the unremitting shuttle of Li polysulfides immensely hinder the practical applications of Li-S batteries. Herein, a compact inorganic layer (CIL) formed by ex situ reactions between Li anode and ionic liquid emerged as an effective strategy to block Li polysulfides and suppress shuttle effect. A CE of 96.7% was achieved in Li-S batteries with CIL protected Li anode in contrast to 82.4% for bare Li anode while no lithium nitrate was employed. Furthermore, the corrosion of Li during cycling was effectively inhibited. While applied to working batteries, 80.6% of the initial capacity after 100 cycles was retained in Li-S batteries with CIL-protected ultrathin (33 μm) Li anode compared with 58.5% for bare Li anode, further demonstrating the potential of this strategy for practical applications. This study presents a feasible interfacial regulation strategy to protect Li anode with the presence of Li polysulfides and opens avenues for Li anode protection in Li-S batteries under practical conditions. (Figure presented.).