Stabilized lithium metal anode by an efficient coating for high-performance Li–S batteries

Lithium-sulfur batteries (LSBs) are one of the most promising energy storage candidates substituted for traditional Li-ion batteries due to their high energy density and natural abundance of sulfur. However, Li metal anode is prone to react with soluble polysulfide produced during the charge/discharge process, leading to the loss of active materials, corrosion of Li metal and fast cell capacity decay. Besides, Li metal anode is also confronted with Li dendrite growth related serious safety concerns. Here, a conformal thin layer of Sn is coated on Li metal surface, which could protect Li metal anode from the parasitic reactions, accommodate the huge volume change and suppress dendritic lithium growth. The symmetric cell using Li foil with Sn coating demonstrates excellent cycling performance with low voltage polarization and uniform, dense and dendrite-free electrodeposited Li metal. In addition, LSBs with Sn coated Li metal anode shows a high specific capacity (1423.7 mAh g−1 at 0.2 C), good rate performance and stable cycling performance with a high Coulombic efficiency of ~99.5% for 500 cycles at 2 C. The superior electrochemical performances are mainly attributed to the Sn protective layer which could enable the fast Li+ transport at the electrode/electrolyte interface, the suppression of Li dendrite growth and the effective minimization of active sulfur loss. This work provides a novel approach and a significant step towards cost-effective, large-scalable and long-cycling stable LSBs.