서강대학교

초록/요약

Lithium-sulfur batteries are seen as next-generation batteries as they can achieve high capacity and theoretical energy density. But there is a problem with sluggish reaction with phase changes included in the course of charge and discharge cycles. The step of changing liquid lithium polysulfides to solid Li2S is needed to improve the kinetics of conversion reaction, since it exposes more than 70% of gross capacity. Research continues to be done to improve the conversion rate by combining carbon or metallic compounds with sulfur, an active material. In this work, the cobalt ions were stabilized by nitrogen doping and the single-atom catalyst was introduced into porous carbon with high surface area. Surface analysis were conducted to check the formation of the single-atom catalyst. Cyclic voltammetry of the symmetrical cells and the morphology of the response formed on electrode were conducted to evaluate the adsorption and response rate by single-atom catalyst. The electrochemical evaluation was performed to confirm the improved performances of the cells because of the Co single-atom catalyst. Compared to the Co catalyst composed of nano or larger units, it showed a high capacity at a fast redox kinetics and a reversible reaction occurred at a stable capacity retention. This is the result of sufficient catalyst amount and pore utilization.