Enhanced sodium storage performance by improving the utilization of NiS through electrode membrane 3D hierarchical porous structure

Abstract

Transition metal sulfides are favorable candidates for anode materials in sodium-ion batteries (SIBs), but they are difficult to fully utilize owing to the agglomeration caused by high interfacial energy at the nanoscale during the process of nanoization or compounding with carbon materials. Herein, we make full use of the advantages of the porous structure of electrode membrane (EM) to obtain a new composite electrode material with nickel monosulfide (NiS) nanoparticles uniformly spread in the membrane pores through covalent bonds. The developed 3D hierarchical porous structure and high specific area of membrane matrix provide strong space for the exposure of NiS active sites, and the NiS nanolayers loaded in the membrane pores also exhibit high porosity, thereby greatly improving its utilization. Compared with pure NiS electrode, it exhibits excellent sodium storage performance during long-term cycles and delivers an inspiring reversible capacitance of 658.3 mA h g−1 at 50 mA g−1. Moreover, the designed composite electrode exhibits excellent flexibility and structural stability before and after long cycles. The favorable performance is the result of the synergy between the 3D hierarchical porous structure and the high utilization of NiS. Considering that the unique porous structure of membrane technology can provide a positive effect on the improvement of NiS utilization, this research provides a simple and feasible design idea for SIBs composite electrodes with high utilization of nano-active materials by porous structural materials.