Multivalence-ion intercalation enables ultrahigh 1T phase MoS2 nanoflowers to enhanced sodium-storage performance

Abstract

Developing rapid charging and robust electrode materials for Na-ion batteries is of considerable significance in large-scale power electricity fields. Herein, the authors have proposed a multivalence-ion intercalation strategy to construct three-dimensional (3D) Co-MoS2 nanoflowers with tailorable 1T/2H phase and interlayer distance. The as-formed S-Co-S covalent bonds serve as “electric bridges” to accelerate interlayer charge transfer without 1T phase degeneration during sodiation and desodiation. Quantum density functional theory (QDFT) calculations further confirm that the optimal Co-MoS2 nanoflowers possess the highest Na adsorption energy with reduced ionic diffusion barrier. Consequently, they deliver a superior sodium-storage capacity of 351 mAh g−1 in 0.4-3.0 V even at 20 A g−1 without capacity fading at 5 A g−1 for 2000 cycles. The high electrochemical reversibility of the 1T phase in Co-MoS2, which accounts for such excellent performance, has been unveiled for the first time by in situ Raman spectra. This finding demonstrates important insights onto promoting two-dimensional (2D) nanomaterials toward rapid charging alkali-ion batteries.