2D-Layer-Structure Bi to Quasi-1D-Structure NiBi₃ : Structural Dimensionality Reduction to Superior Sodium and...

Layer-structured bismuth (Bi) is an attractive anode for Na-ion and K-ion batteries due to its large volumetric capacity and suitable redox potentials. However, the cycling stability and rate capability of the Bi anode are restricted by the large volume expansion and sluggish Na/K-storage kinetics. Herein, a structural dimensionality reduction strategy is proposed and developed by converting 2D-layer-structured Bi into a quasi-1D structured NiBi₃ with enhanced reaction kinetics and reversibility to realize high-rate and stable cycling performance for Na/K-ion storage. As a proof of concept, the quasi-1D intermetallic NiBi₃ with low formation energy, metallic conductivity, and 3D Na/K-ion diffusion pathways delivers outstanding capacity retention of 94.1% (332 mAh g^-1 ) after 15 000 cycles for Na-ion storage, and high initial coulombic efficiency of 93.4% with improved capacity retention for K-ion storage. Moreover, investigations on the highly reversible Na/K-storage reaction mechanisms and cycling-driven morphology reconstruction further reveal the origins of the high reversibility and the accommodation to volume expansion. The finding of this work provides a new strategy for high-performance anode design by structural dimensionality manipulation and cycling-driven morphology reconstruction.