Hierarchical pore Co_xP@Ti₃C₂T_x foams prepared by Co²⁺ induced Self-assembly and in-situ “micron-reactor” phosphating for novel separator modification of lithium-sulfur batteries

Separator-modification attracts increasing attention as a simple and effective resolution strategy for shuttle effect of Li-S batteries. In this work, Co_xP@Ti₃C₂T_x foam with large specific surface areas and hierarchical pore channels is prepared by Co²⁺ induced self-assembly and in-situ “micron-reactor” phosphating. This novel phosphating strategy not only significantly reduces the consumption of phosphorus source (NH₄H₂PO₂), but also facilitates the improvement of CoP_x nanoparticles (NPs) growth and the uniform construction of pore structure on Ti₃C₂T_X nanosheets (NSs) surface. The restacking of Ti₃C₂T_x NSs and agglomeration of Co_xP NPs are effectively inhibited. Then the Co_xP@Ti₃C₂T_x foam is employed for the modification of polypropylene separator, which significantly suppresses the polysulfides (LiPSs) shuttle through the chemisorption by Ti₃C₂T_x NSs and accelerates the redox kinetics and LiPSs conversion via Co_xP NPs as catalysts. Consequently, the Li-S battery shows excellent electrochemical properties, especially at high rate, a high capacity of 691.51 mAh g⁻¹ after 400 cycles at 2.0 C with a decay rate of only 0.037 % per cycle. This work opens a simple, universal, efficient, cost-effective, and environment-friendly strategy for fabricating Ti₃C₂T_x-phosphides foams, which finds diverse applications in energy storage and conversion, catalysis, microwave absorbing/electromagnetic shielding, etc.