Investigation of in situ grown and carbon-free copper sulfide electrode for rechargeable lithium battery

Sulfur and metal sulfides have been the materials of choice for the cathodes to achieve high energy density from lithium based batteries. Among several metal sulfides, copper sulfide has been widely investigated as a positive electrode material for Li-ion batteries. In the present study, in situ preparation of copper sulfide by reaction of sulfur coated on copper foil current collector is investigated. Sulfur is blended with either acetylene black as a conducting agent or TiO2 nanotubes as porous and non-conducting additive and electrodes are prepared on Cu foil. Electrodes are also prepared without any additive. Copper reacts with sulfur forming copper sulfide which has been confirmed by X-ray diffraction studies. Formation of sulfides with platelet like morphology has been observed in all the coatings. Specific discharge capacity of 282 mAh g(-1) has been obtained from S-TiO2 electrode based cell as compared to 317 mAh g(-1) from S-C electrode based cell. Discharge capacity of 230 mAh g(-1) has been obtained from the cells with S electrode without any additive. This is attributed to the higher conductivity of copper sulfide than sulfur and also to the formation of conducting copper particles on discharge. On subjecting the cells to 100 discharge-charge cycles, almost stable performance has been observed with S-TiO2 electrode based cell. Furthermore, the discharge capacity of S-TiO2 based cell is greater than S-C based cell and it increases on repeated cycling. (C) 2017 Elsevier B.V. All rights reserved