Sea urchin-like LiAlO2@NiCoO2 hybrid composites with core-shell structure as high-performance Li storage materials.

Sea urchin-like LiAlO 2 @NiCoO 2 hybrid composites with core-shell structure assembled with nanoneedles have been successfully fabricated through a facile hydrothermal route followed by a calcination procedure in N 2 for the first time. The sea urchin-like architecture with large accessible surface can offer numerous active sites for redox reaction. The synergy of two advantages has dramatically improved the electrochemical behavior in terms of specific capacity, cycle performance and rate capability, especially at high current densities. The LiAlO 2 (5.0 wt%)@NiCoO 2 displays charge capacities are 1309.0 and 933.6 mAh g−1 at 0.5 and 1A g−1, respectively, after 400 cycles. However, the charge capacities of bare NiCoO 2 are only 562.9 and 476.7 mAh g−1 at corresponding rates. Especially, LiAlO 2 (5.0 wt%)@NiCoO 2 preserves 358.1 mAh g−1 after 500 cycles at 2A g−1 with a capacity retention of 74%. The superior electrochemical property is related to the sea urchin-like nature and the ingenious composition design. In addition, the DFT calculation result shows that the formed stable, well-coordinated, and metallic interface between LiAlO 2 and NiCoO 2 are very helpful for reducing the interfacial impedance and beneficial for the improved rate capability of the materials. Therefore, such LiAlO 2 @NiCoO 2 composites with unique morphology demonstrate a huge potential as electrode materials for Li-ion batteries. [ABSTRACT FROM AUTHOR]