ELECTROCHEMICAL PERFORMANCE OF LITHIUM-SULFUR BATTERY USING CONDUCTIVE POLYMER COATED SELENIUM SULFIDE CATHODE AND LITHIATED SILICON ANODE

Abstract

Lithium-Sulfur battery has attracted public attention for their high capacity and low material cost compared with the conventional lithium ion batteries. However, Li-S battery still has a difficulty to be commercialized due to dissolution of lithium polysulfides, low electrical conductivity, low loading mass of active material and forming lithium dendrite on Li metal [1,2,3]. To overcome challenges of Li-S battery, we adopt three materials: (1) SeS2, which has better electrical conductivity than Sulfur (5x10-28 S cm-1) by adopting Selenium component (1x10-3 S cm-1) (2) Conductive polymer to suppress dissolution of high ordered lithium-polysulfides (Li2Sx, 2<x<8) and polyselenides (Li2Sex, 2<x<8) (3) Lithiated Silicon anode which avoid forming Li dendrite and also have high gravimetric capacity (4,200 mAh g-1). Herein, we design the battery using conductive polymer coated selenium sulfide as cathode and lithiated silicon as anode. Fig.1 shows that conductive polymer exceptionally reduced overpotential from 0.38 V to 0.19 V and it enables to utilize more active material with the suppression of dissolution of polysulfides and polyselenides during cycles. Also excellent rate capability performance was achieved as shown in Fig.2