Ultrastable lithium-sulfur batteries with outstanding rate capability boosted by NiAs-type vanadium sulfides

Vanadium sulfides, such as VS 2 , have been often used as sulfur host materials for lithium-sulfur batteries (LSBs), however, their high-symmetry and layered crystalline structure often lead to a poor rate-capability and a limited cycling stability of the resultant LSBs. Thus, in this work, a type of distorted NiAs-type structured V 2 S 3 phase was designed and attempted to use it as a sulfur host for LSBs. The results showed that the prepared V 2 S 3 -nanocrystal decorated carbon nanofiber (CNF@V 2 S 3 ) electrode films are freestanding, highly conductive and flexible. And the resultant CNF@V 2 S 3 /S cathodes show a high specific capacity (1169 mA h g −1 at 0.1C), an excellent rate capability (retain 78.9% at 2.0C), an ultra-low delay rate per cycle of 0.0071%, and a low self-discharge rate of 3.65% per month. A series of analyses indicate that these high electrochemical performances are mainly due to the high polarity, high conductivity and high catalytic activity of V 2 S 3 nanocrystals, as well as the improved diffusivities of Li ions. This research could provide some new insight into the design of sulfur host materials for high-performance LSBs. A new type of vanadium sulfide (V 2 S 3 ) was used for high-performance lithium-sulfur batteries.