Toward Achieving High Kinetics in Anodeless Li2S Battery: Surface Modification of Cu Current Collector

Abstract An anodeless Li 2 S is a promising battery system, which increases volumetric energy density. However, a severe capacity fading in the anodeless Li 2 S is observed at a high current density. Here, it is reported that the surface properties of Cu electrode significantly affect kinetics and cycle stability via controlling Li nucleation and Li metal deposition morphology. A native oxide on the surface increases the Li nucleation underpotential and makes porous Li metal structure because its reaction with the polysulfides during cycles leads to the formation of Li 2 SO 4 and the reduction in the polysulfides. After removing the native oxide, the anodeless Li 2 S cell achieves a fast kinetics up to 10 C (11.66 A g −1 ) with 312 mAh g −1 and stable cycling (120 cycles at 1 C). Furthermore, high‐loading Li 2 S (4.5 mg cm −2 ) anodeless cell is demonstrated by using the modified Cu electrode without the native oxide, achieving good capacity retention for 50 cycles at C/3 and 484 mAh g −1 at reasonable high rate of 1 C. The findings pave the possible way for the practical application of the anodeless Li 2 S battery that has high energy density and fast kinetics.