Electrochemical properties of yolk-shell structured ZnFe₂O ₄ powders prepared by a simple spray drying process as anode material for lithium-ion battery

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.