Bilateral Interfaces in In2Se3-CoIn2-CoSe2 Heterostructures for High-Rate Reversible Sodium Storage

Metal selenides are considered as a group of promising candidates as the anode material for sodium-ion batteries due to their high theoretical capacity. However, the intrinsically low electrical and ionic conductivities as well as huge volume change during the charge-discharge process give rise to an inferior sodium storage capability, which severely hinders their practical application. Herein, we fabricated In2Se3/CoSe2 hollow nanorods composed of In2Se3/CoIn2/CoSe2 by growing cobalt-based zeolitic imidazolate framework ZIF-67 on the surface of indium-based metal-organic framework MIL-68, followed by in situ gaseous selenization. Because of the CoIn2 alloy phase in between In2Se3 and CoSe2, a heterostructure consisting of two alloy/selenide interfaces has been successfully constructed, offering synergistically enhanced electrical conductivity, Na diffusion process, and structural stability, in comparison to the single CoIn2-free interface with only two metal selenides. As expected, this nanoconstruction delivers a high reversible capacity of 297.5 and 205.5 mAh g(-1) at 5 and 10 A g(-1) after 2000 cycles, respectively, and a superior rate performance of 371.6 mAh g(-1) at even 20 A g(-1).

Automated summary

A unique heterostructure composed of In2Se3 and CoSe2 was successfully constructed, leading to enhanced electrical and ionic conductivities, Na diffusion process, and structural stability compared to traditional metal selenides. This nanoconstruction exhibited high reversible capacity and superior rate performance in sodium-ion batteries.