Ni_0.6Fe_0.4Se₂/rGO Heterogenous Nanocubes Anode for Stable and Efficient Na/K‐Ion Storage

Abstract Rational design of electrode materials with cycle stability and high reversible capacity is crucial to the commercial applications of sodium/potassium ion batteries (SIBs/PIBs) in the future. Developing a high‐efficiency anode for SIBs and PIBs, which is formed from the heterogenous Ni‐Fe bimetallic nanocube composite selenide grown on graphene (Ni_0.6Fe_0.4Se₂/rGO, abbreviated as NFSG). The Ni_0.6Fe_0.4Se₂ nanocubes of about 200 nm in which uniformly grown on rGO can provide larger specific surface, broader redox potential, and the stable microchannels to elevate the diffusion rate of Na/K‐ion charge transfer. Utilized as a anode for SIBs, the NFSG electrode exhibits the rate capacity of 366.9 mAh g⁻¹ at 5.0 A g⁻¹ and the longevity of 82.3% circulating over 1000 cycles. For PIBs, NFSG electrode displays the capacities of 335.6 mAh g⁻¹ at 0.05 A g⁻¹ and 108.1 mAh g⁻¹ at 2.0 A g⁻¹ and an outstanding cyclic performance with retained capacity of 260.9 mAh g⁻¹ (0.1 A g⁻¹) after 100 cycles.