Constructing multi-functional composite separator of PVDF-HFP/h-BN supported Co-CNF membrane for lithium-sulfur batteries

作者：Liang, Xin; Wang, Lulu; Wang, Yang; Liu, Yongchao; Sun, Yi; Xiang, Hongfa^*

来源：Sustainable Energy & Fuels, 2022, 6(2): 440-448.

DOI：10.1039/d1se01666k

• GEL POLYMER ELECTROLYTE
• CARBON NANOFIBER
• BORON
• INTERLAYER

The functional design of separators has been proved to be one of the most efficient methods to improve the electrochemical performance of lithium-sulfur batteries. In this work, a multifunctional separator with gradual changes to four aspects was constructed by integrating a PVDF-HFP/h-BN membrane with a Co-doped carbon nanofiber. The architecture has four gradations, which offers multifold advantages. First, in terms of density, there is a transition from loose to dense, which results in a higher electrolyte uptake rate, reduces the amount of free electrolyte and further suppresses the shuttle effect. Additionally, in terms of composition, a transition from inorganic to organic is designed, which allows the inorganic and organic components to bind closely and reduces the interfacial resistance. Meanwhile, there is a transition from high electronic conductivity to insulation. The change in electronic conductivity leads to effective conversion of the polysulfide. Finally, in terms of ionic conductivity, there is a transition from low to high, which gives the separator better ability to conduct lithium ions. As a consequence, a battery with the as-constructed multifunctional separator performs with good capacity stability, which demonstrates a new concept for high-performance lithium-sulfur battery design.