Carbon-Based Porous Bimetallic Phosphide in CNT Network as a Separator for Li–S Batteries

Lithium–sulfur (Li–S) batteries have received continuous attention due to their high theoretical specific capacity. However, the shuttle effect of lithium polysulfides (LiPSs) severely limits its development. Modification of commercial polypropylene (PP) separators is regarded as an effective strategy to suppress the shuttle effect. In this paper, NiFe-PBA-derived carbon-based porous bimetallic phosphide (NFP) was inserted into the carbon nanotube (CNT) networks, and these composites were utilized to modify the PP separator. CNT networks provide abundant pathways of electron transport to improve the conductivity of S cathode and Li 2 S. Ni 2 P and Fe 2 P in NFP exhibit robust chemisorption and catalytic effects on LiPSs. Moreover, porous structures and networks were beneficial for Li + immigration. The synergistic effects of NFP and CNT networks enable the modified separator to obtain a high electrical conductivity, superior adsorption capability, and enhanced catalytic performance. Assembled Li–S batteries show a high initial discharge specific capacity of 1244 mAh g –1 at 0.2 C. Notably, the highest discharge-specific capacity reached up to 938.9 mAh g –1 at 1 C, and the average capacity decay rate per cycle after 300 cycles was a mere 0.067%. This study paves the way for a robust research pathway in harnessing transition metal phosphides and carbon materials for modified separators, offering an effective strategy to realize high-performance Li–S batteries.