Soft-Rigid Heterostructures with Functional Cation Vacancies for Fast-Charging And High-Capacity Sodium Storage.

Optimizing charge transfer and alleviating volume expansion in electrode materials are critical to maximize electrochemical performance for energy storage systems. Herein, an atomically thin soft-rigid Co 9 S 8 @MoS 2 core-shell heterostructure with dual cation vacancies at the atomic interface is constructed as a promising anode for high-performance sodium-ion batteries. The dual cation vacancies involving V Co and V Mo in the heterostructure and the soft MoS 2 shell afford ionic pathways for rapid charge transfer, as well as the rigid Co 9 S 8 core acts as the dominant active component and resists structural deformation during charge/discharge. Electrochemical testing and theoretical calculations demonstrate both excellent Na + transfer kinetics and pseudocapacitive behavior. Consequently, the soft-rigid heterostructure delivers extraordinary sodium storage performance (389.7 mA h g -1 after 500 cycles at 5.0 A g -1 ), superior to those of the single-phase counterparts; and the assembled Na 3 V 2 (PO 4 ) 3 ||d-Co 9 S 8 @MoS 2 /S-Gr full cell achieves an energy density of 235.5 Wh kg -1 at 0.5 C. Our finding opens up a new strategy of soft-rigid heterostructure and broadens the horizons of material design in energy storage and conversion. This article is protected by copyright. All rights reserved.