Building Zn-Fe Bimetal Selenides Heterostructures Caged in Nitrogen-Doped Carbon Cubic for Lithium and Sodium Ion Batteries

Abstract Due to the application of lithium-ion batteries in various convenient electronic devices and electric vehicles, their related study has attracted many researchers' interests. However, the practical application is limited by their fast capacity attenuation, low reversibility and slow charge rate. Sodium-ion batteries have attracted considerable attention in energy storage systems due to similar energy storage mechanisms with lithium-ion batteries and extensive sodium resources on earth. In recent years, Prussian blue analogs (PBAs) and transition metal selenides have attracted many researchers' attention due to their unique structures and high theoretical capacities and have been considered to be the most potential anode materials. However, they have the disadvantages of rapid volume expansion and capacity degradation in the process of lithium insertion /extraction. Here, ZnSe-Fe3Se4 heterostructures coated with N-doped carbon (ZnSe-Fe3Se4@NC) was successfully designed by one-step selenization of Zn-Fe PBA. This unique 3D hierarchical heterostructures can provide a stable environment for lithium ions and sodium ions transportation and shortens the transmission path, which greatly improves the performance of lithium-ion batteries and sodium-ion batteries. The Zn-Fe-Se@NC displays a discharge capacity of 1111.30 mA h g-1 after 100 cycles at 0.2 A g-1 for lithium-ion batteries and 368 mA h g-1 after 60 cycles at 0.1 A g-1 for sodium-ion batteries. This high capacity is mainly attributed to the three-dimensional hierarchical heterostructures coated by N-doped carbon.