Electrochemical properties of MnS-C and MnO-C composite powders prepared via spray drying process

Spherical micron-sized MnS-C and MnO-C composite powders are successfully prepared by post-treating the spray-dried precursor powders. Dextrin, which is used as the carbon source material, plays a key role in the preparation of the composite powders with regular morphologies; the bare MnS and MnO powders prepared from the spray solution without dextrin have irregular morphologies. The MnS-C composite powders prepared from the spray solution containing 17 g L-1 of dextrin have mixed crystal structures of alpha- and gamma-MnS phases. These powders exhibit superior electrochemical properties compared with those of their MnS and MnO-C counterparts. For example, at a current density of 0.5 A g(-1), the MnO-C powders have a 100th-cycle discharge capacity of 321 mA h g(-1); the corresponding discharge capacities of the MnS powders prepared from spray solutions containing 0, 17, and 50 g L-1 of dextrin are 501, 786, and 636 mA h g(-1), respectively. (C) 2015 Elsevier B.V. All rights reserved.