Construct NiSe/NiO Heterostructures on NiSe Anode to Induce Fast Kinetics for Sodium-Ion Batteries

It is of great significance to design and innovate electrode materials with unique structures to effectively optimize the electrochemical properties of the secondary battery. Herein, inspired by neuron networks, an ingenious synthesis is proposed to fabricate NiSe with multidimensional micro-nano structures, followed by in situ construction of NiSe/NiO heterostructures via a temporary calcination. The major structure of bulk NiSe synthesized by the solvothermal method is 3-dimensional micron cluster spherical particles interwoven by uniform one-dimensional nanofibers. Such structures possess the synergistic advantages of nano and micro materials. After a temporary calcination in air, NiSe/NiO heterostructures should be formed in the bulk NiSe, which provides a built-in electric field to enhance diffusion kinetics of sodium ions. This special neural-like network and heterojunction structures ensure the excellent structural stability combined with rapid kinetics of the electrode, releasing 310.9 mAh g⁻¹ reversible capacity after 2,000 cycles at 10 A g⁻¹. Furthermore, the electrochemical storage and ion transport mechanisms are elaborated by electrochemical analysis and theoretical calculation in more detail.