Creating Unidirectional Fast Ion Diffusion Channels in G/NiS 2 -MoS 2  Heterostructures for High-Performance Sodium-Ion Batteries.

Exploring novel electrode composites and their unique interface physics plays a significant role in tuning electrochemical properties for boosting the performance of sodium-ion batteries (SIBs). Herein, mixed-dimensional G/NiS 2 -MoS 2 heterostructures are synthesized in a low-cost meteorological vulcanization process. The stable graphene supporting layer and nanowire heterostructure guarantee an outstanding structural stability to tolerate certain volume changes during the charge/discharge process. The rational construction of NiS 2 -MoS 2 heterostructures induces abundant interfaces and unique ion diffusion channels, which render fast electrochemical kinetics and superior reversible capacities for high-performance SIBs. Interestingly, theoretical studies reveal that the anisotropic diffusion barriers create unidirectional "high-speed" channels, which can lead to ordered and fast Na + insertion/extraction in designed heterostructures. G/NiS 2 -MoS 2 anode exhibits a high capacity of 509.6 mA h g -1 after 500 cycles and a coulombic efficiency >99% at 0.5 A g -1 , which also displays excellent cycling performance with the capacity of 383.8 mA h g -1 after the 1000 cycles at 5 A g -1 . Furthermore, full cells are constructed exhibiting a high capacity of 70 mA h g -1 at 0.1 A g -1 after 150 cycles and applied to light LEDs. This study provides a feasible strategy of constructing mixed-dimensional heterostructures for SIBs with excellent performance and a long service lifetime.