Facile synthesis of WS2/Ni3S2 encapsulated in N-doped carbon hybrid electrode with high rate performance as anode for sodium-ion batteries

The sodium ion batteries (SIBs) are a promising candidate for large-scale energy storage owing to the abundance and low cost of sodium resources. However, the absence of suitable anode materials with desired rate capability and cycle stability is one of the bottlenecks for their commercialization. In this work, WS2/Ni3S2@N-doped carbon composite (WS2/Ni3S2@NC) was prepared by using a simple solvothermal approach with subsequent annealing approach. The material was used as anode material for SIBs. The batteries showed excellent performance due to the special bimetallic sulfide heterostructure, which could provide reaction active sites, promote fast Na ions diffusion, and increase electrode/electrolyte contact. In addition, the in-situ synthesized N-doped carbon layer could effectively improve the electronic conductivity as well as maintain structural stability. As anode of SIBs, the WS2/Ni3S2@NC exhibits both excellent rate performance (329.6 mAh g−1 at 0.1 A g−1, and 129.6 mAh g−1 at 5.0 A g−1) and outstanding cycling stability (219.7 mAh g−1 after 80 cycles at 0.1 A g−1) due to the pseudocapacitive behavior.