Suppression of partially irreversible phase transition in O′3-Na3Ni2SbO6 cathode for sodium-ion batteries by interlayered structural modulation

Abstract

As a promising cathode material for sodium ion batteries, honeycomb-ordered layered Na3Ni2SbO6 still suffers from rapid capacity fading because of partially irreversible phase transition. Herein, a substitution of Na+ by Rb+ with a larger ionic radius in honeycomb layered Na3−xRbxNi2SbO6 is proposed to modulate the interlayer structure. The results unveil that biphasic transition reversibility of the intermediate P′3 phase is substantially enhanced, and the structure evolution behavior during the charge/discharge process changes due to the structural modulation, which contributes to a suppression of the unfavorable O1 phase and an alleviation of the lattice distortion. Moreover, Rb substituted samples exhibited an improved Na+ (de)intercalation thermodynamics and kinetics. Attributed to the modifications, the sample with optimized Rb content delivers superior cycle stability and rate capacity, demonstrating a feasible strategy for suppressing irreversible phase transition and developing high-performance honeycomb layered materials for sodium ion batteries.