The electrochemical study of Li-SeS2 battery in carbonate-based electrolyte depending on carbon matrix design

Abstract

Selenium sulfide (SeS2) is a promising cathode material which has high gravimetric capacity (1,342 mAh g-1) and volumetric capacity (4,026 mAh cm-3). Carbon composite (SeS2/C composite) are used as one of the electrode component materials, which can improve the low electrical conductivity of SeS2 and suppress dissolution of intermediates as well as Li-S batteries. Li-SeS2 batteries are compatible with both ether-based and carbonate-based electrolytes, compared to Li-S batteries, in which ether-based electrolyte are usually used due to the reactivity of carbonate with the dissolved polysulfide during the cycling. In addition, the performances of Li-SeS2 batteries with carbonate-based electrolyte are strongly affected by the carbon composite material structure. Pore volume and morphology of carbon composite affect the SeS2 contents in the SeS2/C composite and discharge voltage etc. In this study, we apply various ordered mesoporous carbon (OMC) to the Li-SeS2 batteries and investigate the relationship between them. Based on the electrochemical studies, we are able to find out the dependency of carbon structure which accomplished high discharge voltage (2.0 V) even containing high SeS2 contents (75 wt.%) by enhancing Li-ion diffusivity. As a result, the Li-SeS2 batteries with advanced carbon morphology show high energy density and excellent cycle performance with average capacity 552 mAh g-1 for 1,600 cycles in carbonate-based electrolyte.