Highly active and reversible NiPSe anode for sodium-ion batteries: enabling ultrafast sodium storage with exceptional cycling stability.

NiPSe exhibits considerable potential as an electrode material for ion batteries due to its low spin-polarization effect, large interlayer spacing, and high intrinsic conductivity, although its ion storage capabilities have not been previously investigated. In this study, two-dimensional NiPSe synthesized via chemical vapor transport is demonstrated to possess exceptional rate capability and ultralong cycling stability, delivering reversible capacities of 277.3 mA h g after 5000 cycles at 20 A g and 249.3 mA h g after 10,000 cycles at 15 A g, along with a high initial Coulombic efficiency of 93.64 % at 1 A g. The fundamental mechanisms underlying the superior performance of NiPSe is elucidated through comprehensive in situ/ex situ characterization and theoretical calculations. The rapid charge transfer kinetics can be attributed to the metallic conductivity, elevated p-band center energy of Se, and preferential Na adsorption at interlayer NiNi sites, while reversible structural evolution is enabled by weak NiSe bonding and low spin-polarization effects. These systematic studies yield significant fundamental understanding regarding the rational design of metal thiophosphate-based materials for next-generation energy storage systems.