Controlled Nucleation and Growth Process of Li₂S₂/Li₂S in Lithium-Sulfur Batteries

Abstract

Lithium-sulfur battery is a very promising energy storage system because of its high specific energy density. However, the dissolution and precipitation of soluble polysulfides during cycling initiate a series of chain reactions that significantly shorten battery lifespan. In order to understand the interfacial reactions occuring on the electrode surfaces, we employ a convenient electrochemical strategy to regulate the nucleation and precipitation of polysulfides on the electrode surface. The accumulation of detrimental Li2S on cathode is largely alleviated thus enabling very stable cycling of Li-S batteries. For example, more than 760 stable cycling are demonstrated with a reversible capacity of 500 mAh g−1. More importantly, the exposure of new lithium metal surface to the S-containing electrolyte is also greatly reduced through this strategy, largely minimizing the anode corrosion caused by polysulfides. The fundamental findings of this work provide valuable information on the electrochemical redistribution process of sulfur, which is unavoidable, during cycling and the corresponding anode evolutions under different testing conditions.