High loading CuS-based cathodes for all-solid-state lithium sulfur batteries with enhanced volumetric capacity
Seyed Milad Hosseini, Alberto Varzi, S. Ito, Yûichi Aihara, Stefano Passerini
Abstract
Transition metal sulfides have shown to improve the performance of lithium-sulfur batteries both with liquid and solid electrolytes. In this work, the beneficial effect of copper sulfide for enabling high areal capacity lithium-sulfur all-solid-state batteries is shown. Copper sulfide-carbon (CuSC) and three different copper sulfide-sulfur-carbon (CuSS) composites are investigated as positive electrodes in all-solid-state lithium-sulfur batteries. The composites are prepared via facile and low-cost mechanochemical ball-milling. It is found that the CuS/C ratio greatly influences the redox properties of the CuSC cathode. Scanning electron microscopy, ex-situ X-ray diffraction, and galvanostatic cycling were also conducted to evaluate the CuSS composite electrodes in Li|LiI–Li3PS4|CuS–S–C solid-state cells. High mass loading cells made using these composite electrodes deliver capacities as high as 1600 mAh g−1(CuS+S) and 7 mAh cm−2 at 20 °C. The higher density of CuS also leads to larger volumetric capacities, up to 3900 mAh cm−3(CuS+S), thus enabling a potential energy density gain up to 15% with respect to a conventional Carbon–Sulfur cathode.