In-situ synthesis of carbon@Ti4O7 non-woven fabric as a multi-functional interlayer for excellent lithium-sulfur battery

Abstract

Lithium-sulfur (LiS) batteries are promising rechargeable batteries because of their low cost, environment-friendly and high energy density. Numerous bi-functional interlayers have been used for enhancing the cycle life of LiS batteries based on novel cell configuration. Most interlayers, however, are conductive carbon materials, which that have weak interactions with polysulfides, and this resulting in fast capacity losing over long-term cycling. Herein, for the first time, carbon@Ti4O7 composite nanofibers (C@Ti4O7 CNFs) have been successfully synthesized using in situ synthetic method. The C@Ti4O7 CNFs interlayer cells have excellent electrochemical performances due to the good restriction of diffused polysulfide, the uniform distribution of final discharge products (sulfides) and the improved conductivity of the whole cathode in charge/discharge process. An initial capacity of 1046 mAh g−1 at 2 C is achieved, with a fade rate of only 0.09% per cycle over 500 cycles, and it finally keeps a capacity of 560 mAh g−1. Even with a high rate of 4 C, the cells still exhibited a favorable specific capacity of 860 mAh g−1 after 25 cycles, and it returns back to a high specific capacity more than 1000 mAh g−1 when the rate is reduced to 0.5 C, and this showing indicated good reversibility.