Electrochemical properties of tungsten sulfide–carbon composite microspheres prepared by spray pyrolysis

Tungsten sulfide (WS(2))–carbon composite powders with superior electrochemical properties are prepared by a two-step process. WO(3)-carbon composite powders were first prepared by conventional spray pyrolysis, and they were then sulfidated to form WS(2)-carbon powders. Bare WS(2) powders are also prepared by sulfidation of bare WO(3) powders obtained by spray pyrolysis. Stacked graphitic layers could not be found in the bare WS(2) and WS(2)–carbon composite powders. The amorphous bare WS(2) and WS(2)–carbon composite powders have Brunauer–Emmett–Teller (BET) surface areas of 2.8 and 4 m(2) g(−1), respectively. The initial discharge and charge capacities of the WS(2)–carbon composite powders at a current density of 100 mA g(−1) are 1055 and 714 mA h g(−1), respectively, and the corresponding initial Coulombic efficiency is 68%. On the other hand, the initial discharge and charge capacities of the bare WS(2) powders are 514 and 346 mA h g(−1), respectively. The discharge capacities of the WS(2)–carbon composite powders for the 2(nd) and 50(th) cycles are 716 and 555 mA h g(−1), respectively, and the corresponding capacity retention measured after first cycle is 78%.