1D hybrid consisting of LiTi₂(PO₄)₃ with highly-active (1 1 3) crystal facets and carbon nanotubes: A bidirectional catalyst for advanced lithium-sulfur batteries

The slow conversion kinetics and shuttle effect of lithium polysulfides (LiPSs) significantly undermine the practical viability of lithium-sulfur (Li-S) batteries. Herein, we rationally develop a bidirectional catalyst consisting of the NASICON-type polyanionic phosphate of LiTi₂(PO₄)₃ nanoparticles semi-embedded on carbon nanotubes (LiTi₂(PO₄)₃/CNTs) toward these challenges. The amorphous carbon can not only regulate the particle size of LiTi₂(PO₄)₃ nanoparticles but also promote its isotropic growth, facilitating the transformation of LiTi₂(PO₄)₃ facets from the thermodynamically more stable (1 0 4) to the highly active (1 1 3). A special hybrid interface of LiTi₂(PO₄)₃ (1 1 3)-C is prepared to enable strong electronic donation from carbon to Ti atoms, which effectively regulates the metal Ti d band center, promotes the d-p orbital hybridization of LiTi₂(PO₄)₃/CNTs and significantly boosts its the catalytic ability for LiPSs. In-situ tests and theoretical calculations indicate that LiTi₂(PO₄)₃/CNTs enhance the adsorption-catalytic ability of LiPSs and reduce the energy barrier of liquid LiPSs to solid Li₂S, thus exhibiting superior electrochemical activity to actuate the translation from intermediates to discharge products. Thanks to the excellent catalytic ability and unique ion characteristics, the LTPC//LTPC@PEP//Li cell shows an impressive rate performance and reversible capability of 818 mAh/g after 300th cycles at 4C.