ZnFe2O4 yolk-shell powders were prepared by applying a simple spray-drying process. Dextrin was used as a drying additive and carbon source material, and thus played a key role in the preparation of the powders. The combustion of precursor powders consisting of zinc and iron salts and dextrin obtained by a spray-drying process produced the yolk-shell-structured ZnFe2O4 powders even at a low post-treatment temperature of 3506C. The ZnFe2O4 powders prepared from the spray solution without dextrin had a filled and pockmarked structure. The initial discharge capacities of the ZnFe2O4 yolk-shell and filled powders post-treated at 4506C at a current density of 500 mA g-1 were 1226 and 993 mA h g-1, respectively, and the corresponding initial Coulombic efficiencies were 74 and 58%. The discharge capacities of the ZnFe2O4 powders with yolk-shell and filled structures post-treated at 4506C after 200 cycles were 862 and 332 mA h g-1, respectively. The ZnFe2O4 yolk-shell powders with high structural stability during cycling had superior electrochemical properties to those of the powders with filled structure.
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (No. 2012R1A2A2A02046367).
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