A lithium–tellurium rechargeable battery with exceptional cycling stability

A Li–Te rechargeable cell with exceptionally high specific capacity and cycling stability at high charge/discharge rates is presented. The cell was composed of a Te/mesoporous carbon CMK-3 composite positive electrode and a Li metal negative electrode. The Te/CMK-3 electrode was prepared using a melt diffusion process and characterized using scanning electron microscope, X-ray diffraction, and Brunauer–Emmett–Teller surface area analysis. Cyclic voltammograms of the Te/CMK-3 electrode suggested reversible (de)lithiation of Te at 1.63/1.88 VLi+/Li combined with irreversible formation processes. Initial cell cycling for formation process revealed voltage plateaus consistent with the cyclic voltammograms until a stationary capacity of about 400 mA h g−1 at 1C with 100 % coulombic efficiency was reached. Discharge capacities retained 96 % (0.5C), 86 % (1C), 78 % (2C), and 69 % (5C) of the theoretical specific capacity. Long-term cyclability tests involving 1000 charge/discharge cycles at 10C rate delivered an unprecedented specific capacity of 286 mA h g−1 at essentially 100 % coulombic efficiency (85 % capacity retention). The study bears testimony to the favorable high-rate stability of the Li–Te/CMK-3 cell design outperforming previously reported chalcogen-based electrode systems.