Accurate hierarchical control of hollow crossed NiCo2O4 nanocubes for superior lithium storage

Abstract

An effective approach of simultaneously coordinating etching and precipitation reactions is employed to prepare hollow crossed NiCo₂O₄ nanocubes as anode materials for lithium-ion batteries. Firstly, amorphous hollow (NiCo_x)O(OH) nanoboxes form uniformly, and subsequent calcination results in the formation of NiCo₂O₄ nanocubes that exhibit a stable reversible capacity of 1160 mA h g⁻¹ at constant current density of 200 mA g⁻¹ with capacity retention of over 91.1% after 200 cycles. The unique hollow structure can shorten the Li-ion diffusion path, which benefits the rate of performance. Furthermore, the hollow structure offers a sufficient void space to alleviate the mechanical stress caused by volume change. Additionally, the multi-element characteristics of active materials allow the volume change to take place in a stepwise manner. Therefore, hollow crossed NiCo₂O₄ nanocube electrodes exhibit excellent electrochemical performance. This method is simple and of low cost, which may open a new avenue for fast synthesis of hollow crossed structural nano-functional materials for energy storage, catalysts, sensors and other new applications.