Ultrastable lithium–sulfur batteries with outstanding rate capability boosted by NiAs-type vanadium sulfides
Vanadium sulfides, such as VS2, 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 V2S3 phase was designed and attempted to use it as a sulfur host for LSBs. The results showed that the prepared V2S3-nanocrystal decorated carbon nanofiber (CNF@V2S3) electrode films are freestanding, highly conductive and flexible. And the resultant CNF@V2S3/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 V2S3 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.
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