Dual‐Bond Confinement Enhanced Polyphosphides Adsorption and Electrochemical Kinetics in Metal Phosphides Anodes for Reversible and Stable Lithium/Sodium Storage

Abstract Metal phosphides exhibit high energy densities as hosts for lithium/sodium storage owing to their conversion reaction mechanism. Nevertheless, they typically suffer from inferior reversibility and cyclability because of the dissolution of polyphosphides and sluggish electrochemical kinetics. Herein, a series of dual‐bond confined MXene‐M x P y ‐G composites have been fabricated, in which M x P y nanoparticles are strongly bound with MXene and graphene nanosheets via Ti─P and C‐P bonds. On one hand, the dual‐bond confinement offers strong adsorption to trap polyphosphides, greatly stabilizing the conversion‐formed products during cycling. On the other hand, dual‐bond immobilization largely promotes electron transfer and ion diffusion, facilitating the reversibility of conversion reactions. As anticipated, these MXene‐M x P y ‐G hybrids demonstrate superb lithium/sodium‐storage performance. Particularly, as an anode for lithium‐ion batteries, the MXene‐Sn 4 P 3 ‐G delivers a high initial coulombic efficiency of 90.1% and a high reversible capacity of 1058.6 mAh g −1 at 0.2 A g −1 . Even tested at high rates of 1.0/2.0 A g −1 , it can still maintain high reversible capacities of 820.6/726.5 mAh g −1 after 1450 cycles. When applied in pouch full‐cells and sodium‐ion batteries, it also shows extended cyclic lifespans of 350 and 1200 cycles. This work provides new insights to improve the reversibility and cyclability of conversion‐type anodes.