Self-assembled hierarchical porous NiMn₂O₄ microspheres as high performance Li-ion battery anodes

Hierarchical structured porous NiMn₂O₄ microspheres assembled with nanorods are synthesized through a simple hydrothermal method followed by calcination in air. As anode materials for lithium ion batteries (LIBs), the NiMn₂O₄ microspheres exhibit a high specific capacity. The initial discharge capacity is 1126 mA h g^-1. After 1000 cycles, the NiMn₂O₄ demonstrates a reversible capacity of 900 mA h g^-1 at a current density of 500 mA g^-1. In particular, the porous NiMn₂O₄ microspheres still could deliver a remarkable discharge capacity of 490 mA h g^-1 even at a high current density of 2 A g^-1, indicating their potential application in Li-ion batteries. This excellent electrochemical performance is ascribed to the unique hierarchical porous structure which can provide sufficient contact for the transfer of Li⁺ ion and area for the volume change of the electrolyte leading to enhanced Li⁺ mobility.