Comparison of the electrochemical properties of yolk-shell and dense structured CoFe₂O₄powders prepared by a spray pyrolysis process

CoFe₂O₄powders with yolk-shell and dense structures are both prepared by a simple spray pyrolysis process with the same preparation conditions. Sucrose dissolved in the spray solution changes the morphology from a dense structure into a yolk-shell structure. In the initial cycle, the yolk-shell CoFe₂O₄powders exhibit discharge and charge capacities of 1158 and 902 mA h g^-1respectively, at a current density of 1 A g^-1, while the dense CoFe₂O₄powders exhibit capacities of 1071 and 677 mA h g^-1, respectively. After 200 cycles, the capacity retentions of the yolk-shell and dense powders after the first cycles are 83 and 47%. The yolk-shell powders exhibit not only good cycling stability but also good rate performance compared with the dense powders because of their structural advantages. This journal is