Tungsten sulfide (WS2)-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 WS2-carbon powders. Bare WS2 powders are also prepared by sulfidation of bareWO 3 powders obtained by spray pyrolysis. Stacked graphitic layers could not be found in the bare WS2 and WS2-carbon composite powders. The amorphous bare WS2 and WS2-carbon composite powders have Brunauer-Emmett-Teller (BET) surface areas of 2.8 and 4 m2 g -1, respectively. The initial discharge and charge capacities of the WS2-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 WS2 powders are 514 and 346 mA h g-1, respectively. The discharge capacities of the WS2-carbon composite powders for the 2nd and 50th cycles are 716 and 555 mA h g-1, respectively, and the corresponding capacity retention measured after first cycle is 78%.
|Publication status||Published - 2014 Aug 29|
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