Preparation of Li2S-FeS2 composite electrode materials and their electrochemical properties

Abstract

Li2S-FeS2 composite positive electrode materials were prepared for improving the discharge capacity of the allsolid-state In/Li 2S cells via the electrical conductivity enhancement of Li 2S. The electrochemical tests demonstrated that the In/Li 2S-FeS2 (Li2S: FeS2 = 3:7 wt) cells showed relatively higher discharge capacity (ca. 180 mAh • g-1, normalized by the cathode weight) than that of the In/Li2S-C cells (ca. 140 mAh •g-1), due to the increased fraction of the active materials in the cathodes. The ex-situ XRD and S K-edge XAFS results indicated that the In/Li2S-FeS2 cells showed similar electrochemical reaction to that of the Li/Li2S-FeS2 cells with liquid electrolytes during charge, but did not proceed to form Li2S and Fe during discharge. Such difference was due to the limited amounts of Li ions supplied from the lithiated-In anode during discharge for the In/Li 2S-FeS2 cells.