Abstract
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The design of hierarchical nanostructures to be used as anodes (involving higher rate capabilities and better cycle lives) and meet further lithium ion battery applications has attracted wide attention. Herein, a hierarchical MnO2@NiO core-shell nanostructure with a MnO2 nanorod as the core and NiO flakes as the shell has been synthesized by combining a hydrothermal treatment and an annealing process. MnO2 nanorods serve as a high theoretical capacity (1233 mA h g-1) material, and they allow efficient electrical and ionic transport owing to their one-dimensional structure. The porous NiO flakes used as the shell would enlarge the contact area across the electrode/electrolyte, and can also serve as volume spacers between neighboring MnO2 nanorods to maintain electrolyte penetration as well as reducing the aggregation during Li+ insertion/extraction. As a result, the MnO2@NiO core-shell structure exhibits improved cycling stability (939 mA h g-1 after 200 cycles at a current density of 1 A g-1) and outstanding rate performance, suggesting that the synergetic effect and characteristics of the core-shell nanostructure would benefit the electrochemical performance of lithium ion batteries.