Ultrafast Synthesis of Yolk-Shell and Cubic NiO Nanopowders and Application in Lithium Ion Batteries

摘要

A continuous one-pot method was employed to synthesize yolk-shell and single-crystalline cubic NiO powders in a few seconds, Submicrometer-sized NiO yolk-shell particles were prepared by spray pyrolysis at 900 °C. Single-crystalline cubic NiO nanopowders were prepared by one-pot flame spray pyrolysis from NiO vapors. Particle surface areas of the yolk-shell and single-crystalline cubic NiO powders as obtained using the Brunauer—Emmett—Teller method were 8 and 5 m~2 g~(-1), respectively. The mean crystallite sizes of the yolk-shell-structured and cubic NiO powders were 50 and 80 nm, respectively The yolk-shell and single-crystalline cubic NiO powders delivered discharge capacities of 951 and 416 mA h g~(-1), respectively, after 150 cycles, and the corresponding capacity retentions measured after the first cycle were 106 and 66%, respectively. The yolk-shell-structured NiO powders showed rate performance better than that of the single-crystalline cubic NiO nanopowders. Even at a high current density of 1 A g~(-1), the discharge capacity of the yolk-shell-structured NiO powders was as high as 824 mA h g~(-1) after 50 cycles, in which the current densities were increased stepwise.