A conductive polymer derived N-doped carbon nanofiber supported Li2S coating layer for Li–S batteries with high mass loading

Abstract

The commercialization of Li2S as a potential candidate for lithium-sulfur cathode material is hampered due to its low electronic conductivity, the “shuttle effect” and the initial energy barrier. In this work, nanosized Li2S particles coated carbon nanofibers are prepared via a solution-based chemical method. Benefiting from this synthetic method, a uniform Li2S layer can be obtained without any agglomeration. Due to the small size of Li2S particles, a smaller energy barrier is observed in the first charging process, which means it is easier to activate the Li2S with a smaller cut-off voltage. In addition, the carbon nanofibers as matrixes could enhance the conductivity of cathode. Moreover, to verify the potential practical application of prepared materials, Li2S cathodes with high loading amount of active materials (∼3 mg cm−2) are prepared, which show excellent cycling and rate performance, delivering an initial specific capacity of 916.2 mA h g−1 at 0.1C, and 321 mA h g−1 capacity still can be reached at 2 C. This good performance can be attributed to the unique solution-based synthesis method, resulting in small and uniform Li2S particles coated on carbon nanofibers.