Heterojunction-structured Ni0.85Se/CoSe nanoparticles anchored on holey graphene for performance-enhanced sodium-ion batteries

Abstract

Graphene-based metal selenides, are increasingly recognized for their potential in sodium-ion battery applications due to their superior electrochemical properties. The unique structure of graphene facilitates rapid in-plane transport of sodium ions, but the interlayer diffusion remains a significant challenge. The Ni_0.85Se@CoSe heterojunctions, strategically grown adjacent to the graphene pores, offer a novel solution by creating in-plane holes that serve as direct channels for vertical ion transport, thereby enhancing cross-layer sodium ion permeation. The incorporation of Ni_0.85Se@CoSe heterojunctions with holey graphene (NCS/HG) significantly enhances the reaction dynamics between sodium ions and anode material. These heterojunctions not only promote easier sodium ion insertion/extraction process by reducing the Na⁺ adsorption energy, but also improve the electrical conductivity by adjusting the band gap. The configuration supports high current density applications (573.5 mAh/g at 5.0 A/g), and ensures robust cycle stability with a capacity retention rate of 97 % after 1000 cycles at 2.0 A/g. Therefore, the development and etching techniques employed in engineering the Ni_0.85Se@CoSe/HG graphene-based anodes exemplify a significant advancement in anode material design, highlighting the importance of material architecture in the development of high-performance energy storage devices.