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

Abstract

An anodeless Li2S is a promising battery system, which increases volumetric energy density. However, a severe capacity fading in the anodeless Li2S 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 Li2SO4 and the reduction in the polysulfides. After removing the native oxide, the anodeless Li2S 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 Li2S (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 Li2S battery that has high energy density and fast kinetics.