Self-supported nickel-coated NiO arrays for lithium-ion batteries with enhanced capacity and rate capability

Self-supported nickel-coated NiO arrays are prepared by chemical bath deposition of NiO flake arrays followed by magnetron sputtering of nickel nanoparticles. The effect of sputtering time, namely, coverage of nickel nanoparticles, on the lithium storage performance of Ni-coated NiO array electrode is investigated. It is found that the optimum sputtering time is 60 s, and such electrode delivers a reversible capacity of 455, 316 and 187 mAh g−1 at a current density of 2, 4 and 7.18 A g−1, respectively, higher than the bare NiO array electrode. The deposited nickel nanoparticles keep the NiO active particles electrically connected and thus improve the electronic conductivity, and also stabilize the flake microstructure during cycling, resulting in the increase in reversible capacity and rate capability. The Ni-coated NiO array electrode, however, is still suffered from a large voltage hysteresis, indicating that the enhanced electronic conductivity is not effective on decreasing this hysteresis.