π–π stacking of unsaturated sulfonates on natural graphite enables a green and cost-effective cathode for high-voltage dual-ion batteries

Abstract

A sustainable and cost-effective energy storage system is the research focus at present and also the development direction of the future. A green and cost-effective cathode material for high-voltage dual-ion batteries (DIBs) is presented in this work through the artificial implantation of unsaturated organic sulfonates on the surface of natural graphite (NG) particles via a low-cost and green synthesis route. It is interesting to discover and validate that π–π stacking interactions exist between the π-bonds of unsaturated sulfonates and graphite layers through both practical experiments and density functional theory simulations. The CC bond-containing propyne sulfonate (PyS) exhibits stronger π–π stacking interactions on graphite layers than the CC bond-containing allyl sulfonate and C–C bond-containing propane sulfonate. The PyS layer works as an artificial and highly stable cathode/electrolyte interphase (CEI), which effectively precludes electrolyte decomposition, reduces interfacial resistance and protects the NG cathode from structural degradation. The as-prepared NG@PyS exhibits outstanding cycling performance as the cathode material of DIBs by virtue of the high adhesion capability of PyS on graphite.