Wrapping 2D layered VSe2 nanoplates in 3D carbon nanotube network for high-rate and long-cycling sodium storage capability in ether electrolytes

The layered transition metal diselenides are promising anode materials for sodium ion batteries, attributed to their large interlayer spacing and decent capacities. It is still a challenge to achieve long-term cycling and high-rate capability because of the serious volume effects and unsatisfied conductivity. In this work, the hierarchical architectures consisting of VSe2 nanoplates wrapped into the carbon nanotubes network (VSe2/CNT) are prepared through a simple hydrothermal method. Benefiting from the high conductivity and the structure protection of CNT network and the abundant Se vacancy in VSe2, the reaction kinetics and structure stability of the VSe2/CNT anode are significantly enhanced for sodium storage. Consequently, a discharge capacity of 170 mAh g−1 can be maintained over 10000 cycles at 2.0 A g−1 with a low capacity decay rate of 0.0048% per cycle, and a high capacity of 167 mAh g−1 is achieved at 100 A g−1 for the rate performance. Moreover, combinational modulations of electrolyte and electrode can take a synergetic influence on the electrochemical behaviors. The ether-based electrolyte has a lower stable overpotential, which promotes fast sodium storage. The CNT network passivation can suppress the “under-voltage failure” phenomenon, thereby providing superior cycling stability.