A Study on the Li-SeS2 batteries with Synthesis Procedure, Electrolyte and Cathode Material

Abstract

Selenium sulfide(SeS2) is a promising next-generation secondary batteries cathode material due to its large capacity (1,342 mAh g-1, 4,026 mAh cm-3). Due to its low electrical conductivity, SeS2 is used with porous carbon. And cell performance is highly affected by porous carbon. In this study, we investigated the correlation between cell performance and porous carbon with small pore volume and large pore volume. Porous carbon with small pore volume is unfavorable to electrolyte mass transport in electrode. Therefore, a new synthesis procedure was applied and the electrolyte was studied for carbon with small pore volume. Increasing discharge voltage and working at high current was possible by applying the synthesis procedure that can removed excess SeS2 without decomposition. The electrolyte comparison shows that carbonate based electrolyte with high viscosity and dielectric constant is disadvantageous to Li-ion diffusion thus lead to work at low discharge voltage. The carbonate based electrolyte are more stable for long cycle than ether based electrolyte because the polysulfide/polyselenide is less soluble. Porous carbon with small pore volume which cause the slow Li ion diffusion is affected by the contents of SeS2 and electrolyte. Otherwise, the porous carbon with large pore volume enables high SeS2 loading in composite. Moreover, it can overcome the disadvantage of carbonate based electrolyte by make many Li ion diffusion path with taking the advantage of long cycle life.