Electrochemically active lithium sulfide-carbon (Li2 S-C) composite positive electrodes, prepared by the spark plasma sintering process, were applied to all-solid-state lithium secondary batteries with a Li3 PO4 - Li2 S- SiS2 glass electrolyte. The electrochemical tests demonstrated that In/ Li2 S-C cells showed the initial charge and discharge capacities of ca. 1010 and 920 mAh g-1 - Li2 S, respectively, which showed higher discharge capacity and coulombic efficiency (ca. 91%) than the Li/ Li2 S-C cells with nonaqueous liquid electrolytes (ca. 200-380 mAh g-1 - Li2 S and ca. 27%, respectively). The ex situ S K-edge X-ray absorption fine structure measurements suggested the appearance and disappearance of elemental sulfur in the positive electrodes after charging and discharging, respectively, indicating that the ideal electrochemical reaction Li2S 2Li+S proceeded in the present all-solid-state cells. Such ideal electrochemical reaction, due probably to the suppression of the dissolution of Li2 S in the form of polysulfides into the electrolytes, would result in higher coulombic efficiency and discharge capacity as compared with those of the liquid-electrolyte cells.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films
- Materials Chemistry