Hierarchical NiCoO2 mesoporous microspheres as anode for lithium ion batteries with superior rate capability

•Hierarchical NiCoO2 microspheres built with mesoporous thorn arrays is developed.•The obtained NiCoO2 exhibits superior rate capability and promoted cyclic stability.•The hierarchical microspheres structure could obtain relatively higher tap density.•NiCoO2 with relatively lower surface area exhibits a suppressed side reaction.•Mesoporous NiCoO2 spheres show short diffusion distance, proper active area for Li+.

Nanostructured materials with small particle size and large surface area exhibit excellent rate capability, however, their cyclic performances are normally limited by the intemperate side reaction with electrolyte, which is resulted from the large contact surface area of nanosized active particles with electrolyte. To avoid this issue, a relatively denser NiCoO2 (NCO) hierarchical microspheres built by mesoporous thorn array are developed by pyrolyzing the agave-stricta-like NiCo(OH)2CO3 thorn microspheres under nitrogen gas in this work. The analysed experimental results suggest that the hierarchical mesoporous nanostructure constructed by interconnected nanoparticles with a proper size (neither too small nor to large) shows a favorable BET specific surface area to well balance the rate and cyclic performance of transition metal oxide anodes. Compared to reported similar works, the as-prepared hierarchical NCO mesoporous microspheres deliver superior rate capability and greatly promoted cyclic stability, i.e. 844.6, 627.9 and 396.6 mA h g−1 at 80, 1600 and 4000 mA g−1, respectively.

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