Bimetallic heterojunctions supported by porous carbon used for cycle life breakthroughs in sodium-ion batteries

This study prepared a bimetallic sulfide heterostructure composite material composed of Ni 3 S 2 @Co 9 S 8 nanoparticles embedded in a biomass-derived porous carbon framework, which is used for the first time to enhance the electrochemical performance of sodium-ion batteries. In this composite material, the heterojunction interface and lattice defects create more uniform sodium ions (Na + ) transport pathways, which enhance the Na + transport efficiency. Additionally, the mesopores within the porous carbon framework can confine the metal sulfide particles to a nanometer scale, effectively mitigating the adverse effects of significant volume expansion during charge and discharge cycles. The synergistic effect of these two factors significantly improves the electrochemical performance of batteries based on this electrode materials. Compared with previous works, the combination of a porous carbon skeleton and bimetallic heterostructure not only enhances cycling stability but also improves reversible capacity under high current densities. Electrochemical tests show that after 6000 cycles at a high current density of 10 A g −1 , the reversible capacity remains at 225.63 mAh g −1 , with a capacity decay rate of less than 0.0003 % per cycle, demonstrating excellent cycle stability and superior rate performance. This research provides new design insights for the development of high-performance anode materials for sodium-ion batteries. • Heterojunction interface can accelerate Na + transport and ease volume expansion. • Carbon skeleton improves conductivity and stabilizes electrode structure. • Lattice defects provide buffer sites for heterostructure to ease volume expansion. • Multi-pronged relief mechanism significantly enhances the cycling lifespan. • A cycle capacity decay rate of 0.0003 % per cycle at 10 A g-1 after 6000 cycles.