Fe/Ni ₂ P-Modified Porous Carbon Microtubes as Sulfur Host and Separator Modification Layer for Lithium–Sulfur Batteries

Ni 2 P/Fe-modified porous carbon microtubes (Fe/Ni 2 P-PCMT) with high specific surface area and rich pore structure are obtained from renewable palm thread by a freeze-drying–calcination process. Due to the triple effect of “constraint–adsorption–catalysis” toward lithium polysulfides, Fe/Ni 2 P-PCMT significantly enhances the electrochemical performance of lithium–sulfur batteries both as S-host or modification coating of separator. The cell using Fe/Ni 2 P-PCMT as cathodic S-host delivers a high initial capacity of 1140.1 mAh g –1 at 0.1 C, and the capacity decay rate is only 0.077% per cycle after 600 cycles at 1 C. In addition, Fe/Ni 2 P-PCMT can also be applied to modify polypropylene (pp) diaphragm, the cell assembled with Fe/Ni 2 P-PCMT-modified separator and commercial Kochen black cathode delivers a higher initial capacity of 1311.4 mAh g –1 at 0.1 C, which is much higher than that of pure pp separator (968.1 mAh g –1 ), and its initial capacity can still reach 663.3 mAh g –1 at a high current density of 5 C, with a low capacity decay rate of 0.069% per cycle after 600 cycles at 1 C. This study opens up a path to construct advanced lithium–sulfur batteries using sustainable biomass-derived porous carbon microtubes.