• anode materials;
  • energy conversion;
  • lithium ion batteries;
  • nanoparticles;
  • spray pyrolysis


The electrochemical properties of yolk–shell-structured, multi-component, transition-metal oxides have not yet been properly compared to those of hollow-structured or nanoscale powders. In this study, yolk–shell, hollow, and single-crystalline ZnCo2O4 powders with uniform compositions are prepared by using simple gas-phase reaction methods. Double-shelled ZnCo2O4 yolk–shell powder is prepared directly from the spray solution by using spray pyrolysis. Single-crystalline ZnCo2O4 nanopowder is prepared by means of flame spray pyrolysis. The yolk–shell ZnCo2O4 powder shows higher charge and discharge capacities than the hollow and single-crystalline powders. The yolk–shell, hollow, and single-crystalline ZnCo2O4 powders deliver discharge capacities of 753, 586, and 206 mAh g−1, respectively, after 200 cycles at a charge/discharge rate of 3 A g−1, and the corresponding capacity retentions measured after the first cycle are 99, 74, and 27 %, respectively. The yolk–shell ZnCo2O4 powders are structurally stable during cycling and have good electrochemical properties even at high current densities.