LAUSR

An efficient Li-S redox catalyst of MWCNTs covalently modified by cobalt (II) tetraaminophthalocyanines (TaPcCo-MWCNTs) is reported. Effective lithium polysulfide (LiPS) capturing is enabled by the lithiophilic N-containing phthalocyanine rings and the sulfiphilic Co central atoms. This adsorption geometry utilizes the Co unoccupied d-orbitals as electron superexchange highways. Elevated kinetics of LiPSs reactions in the liquid phase as well as liquid-solid transitions are revealed by electrochemical measurements and density functional theory calculations. Uniform deposition of Li 2 S films is also observed that preserves cathode integrity and sulfur utilization during cell cycling. The catalysed sulfur redox is also greatly facilitated by the fast electron and Li-ion transport to and from the reaction sites via the conductive MWCNT skeletons and the lithiophilic substituent amino groups on TaPcCo. With 6 wt% addition of TaPcCo-MWCNT in the cathode coatings, high sulfur utilization is achieved with areal sulfur loadings up to 7 mg cm -2 . Stable long-term cycling is achieved at 1C under 5 mg cm -2 of sulfur loading, with an initial areal capacity of 4.4 mAh cm -2 and a 500-cycle retention of 3.5 mAh cm -2 . Considering the high structural diversity of phthalocyanines macromolecules, this study offers opportunities for a new class of Li-S catalysts.