Constructing a rapid ion and electron migration channels in MoSe2/SnSe2@C 2D heterostructures for high-efficiency sodium-ion half/full batteries

Sodium-ion batteries (SIBs) have been expected to replace lithium-ion batteries (LIBs) in the future. However, due to the large radius of Na+, it is prone to volume expansion during the charge and discharge process. Therefore, the development of high capacity anode materials for SIBs remains a huge challenge. As a commonly used battery anode material, transition metal selenide has the advantages of high theoretical capacity, remarkable electrical conductivity and low environmental pollution. Unfortunately, due to the dramatic volume variation and large polarization of metal selenides during charging and discharging, the aggregation of active substances and the destruction of structures hinder practical applications in battery devices. In this paper, MoSe2/SnSe2@C composite with a 2D van der Waals heterostructure structure was successfully synthesized by simple hydrothermal reaction and heat treatment. The heterojunction structure allows lattice distortion and electron redistribution at the phase interface, thereby accelerating ion migration and charge transition. At the same time, the introduction of porous carbon improves the electronic conductivity of the materials. As a result, the as-prepared MoSe2/SnSe2@C composite maintains a discharge capacity of 591.4 mAh g−1 after 110 cycles at 0.1 A g−1 and excellent long cycle performance of 334 mAh g−1 after 200 cycles at 0.5 A g−1 for SIBs. The material also showed outstanding electrochemical performance in full cell tests, demonstrating a promising commercial potential.