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Keywords:

  • electrodes;
  • batteries;
  • nanostructures;
  • spray pyrolysis;
  • yolk–shell powders

Abstract

Several yolk–shell-structured CuO–Fe2O3 powders with various Cu/Fe molar ratios have been successfully prepared under equivalent reaction conditions using a one-pot spray pyrolysis process. The Cu and Fe components are uniformly distributed throughout the powders, irrespective of composition. The Brunauer–Emmett–Teller surface areas of the yolk–shell CuO–Fe2O3 systems increased from 5 to 16 m2 g−1 if the Cu/Fe molar ratios are decreased from 3:1 to 1:3. The initial discharge and charge capacities of the yolk–shell CuO–Fe2O3 system (Cu/Fe=1:2), showing maximum values at a constant current density of 1000 mA g−1, are 1436 and 1012 mA h g−1, respectively. After 130 cycles, the discharge capacities of the yolk–shell CuO–Fe2O3 powders with Cu/Fe molar ratios of 1:3, 1:2, 1:1, 2:1, and 3:1 are 1159, 1151, 755, 655, and 651 mA h g−1, respectively. The discharge capacities of the yolk–shell and dense powder samples after 50 cycles, when subjected to a series of current density increases from 500 to 5000 mA g−1, are 735 and 495 mA h g−1, respectively.