Enhancement of Electrochemical Redox Reaction by Transition Metal Oxalate for High-Performance Lithium-Sulfur Batteries

Abstract

As the size and usage of electronics are diversified, demand for secondary batteries with higher capacity and performance is increasing. Lithium-sulfur(Li-S) battery is one of the promising next generation battery due to high theoretical capacity(1,672 mAh g-1), natural abundance and environmental nontoxic compare to conventional active materials of lithium-ion batteries. However, lithium polysulfide(PS) dissolution issue which causes capacity fade inevitably must be overcome for commercialization. In this study, five transition metal oxalates were investigated as cathode additives which have a high polar surface area to enlarge the electrocatalytic interfacial boundary enabling LiPS redox reactions to occur. For this, Physicochemical interactions between LiPS and metal oxalates were verified by UV-vis and cyclic voltammetry(CV). As a result, the modified cathode by the best candidate, CoC2O4·2H2O effectively decreased cell overpotential and improved the cycle stability by maximized electrochemical utilization.