it-conjugated organic compounds: A universal anode for monovalent (Li, Na) and divalent (Mg, Ca) ion batteries

Organic electrode materials, as the next-generation promising anodes for monovalent (Li/Na) and multivalent (Mg, Ca) ion batteries, still face many challenges such as low capacity, easy dissolution, and electronic insulation. Herein, taking it-it conjugated polymeric macromolecular as a typical example, the relationships between the molecular structure of organic material and capacity, solubility, and conductivity are investigated through theoretical calculations. The results show that the it-it interaction between macromolecular forms a stable composite structure, which can effectively inhibit the dissolution of organic materials and ensure the rapid transmission of electrons during the electrochemical reaction, and the combination of benzene rings and amides largely increases the redox sites to improve specific capacity. Based on this molecular structure design, a novel nearly planar polymerized macromolecule, aromatic polyamides (APAS), is synthesized by ball milling to initiate the in-situ polymerization of 1, 3, 5-benzenetricarbonyl chloride and 1, 4-phenylenediamine on the surface of ultra-thin nitrogen-doped reduced graphene (N-rGO). The APAS@N-rGO is highly insoluble in carbonate electrolytes and exhibits excellent reversible capacities of monovalent-ion (490 mAh g-1 for Li+ and 328 mAh g-1 for Na+) and multivalent-ion (120 mAh g-1 for Mg2+ and 114 mAh g-1 for Ca2+) batteries with excellent stabilities. Our work provides molecular structure design inspiration for the development of organic electrode materials with multiple active sites, high insolubility, and electron conductivity.