Self-supporting NiSe2@BCNNTs electrode for High-Performance sodium ion batteries

Highly conductive metal selenides have attracted considerable attention as a conversion-type anode of sodium-ion batteries (SIBs). However, their poor rate capability, sluggish reaction kinetics, and rapid capacity fading greatly hinder their large-scale commercial application. In this work, a novel self-supporting NiSe2 composite encapsulated in boron carbonitride (BCN) nanotubes (NiSe2@BCNNTs) was prepared through a simple pyrolysis method. The self-supporting NiSe2@BCNNTs conductive matrix creates native 3D electron transfer paths, accelerating the ionic and electronic diffusion/transport kinetics. Benefiting from these merits, the as-made NiSe2@BCNNTs anode exhibits a remarkable reversible Na+ storage capacity (787 mAh g−1 at the current density of 100 mA g−1) and superior long-term cycling stability (382.4 mAh g−1 at 2 A g−1 after 2000 cycles). Furthermore, the assembled NiSe2@BCNNTs//Na3V2(PO4)3/N-CNTs full-cell delivers a high reversible capacity of 72.8 mAh g−1 at 0.5 A g−1 after 500 cycles, indicating its potential for SIBs application..