A Trimeric-Imidazole Ring-Containing Naphthoquinone Compound with Hydrogen Bonds for High-Performance Lithium-Ion Batteries

Abstract

Naphthoquinones exhibit significant potential as cathode materials in rechargeable organic lithium-ion batteries due to their customizable molecular structure and high theoretical specific capacities. However, their low utilization of redox-active sites and high solubility result in poor electrochemical performance. In response to this challenge, an insoluble trimeric-imidazole ring-containing small molecule with hydrogen bonding, 2,2′,2′′-(2,4,6-trihydroxybenzene-1,3,5-triyl)tris(1H-naphtho-[2,3-d]imidazole-4,9-dione) (TDMNQ), was designed and synthesized. Benefiting from the π-conjugated trimeric structure, containing an imidazole ring and a hydroxyl group that forms intramolecular hydrogen bonds, TDMNQ exhibits excellent chemical/structural stability along with outstanding electrochemical performance. Lithium-ion batteries employing TDMNQ as the cathode exhibit an active site utilization of up to ∼90% at 0.1 A g −1 , achieving a high energy density of 422 Wh kg −1 , along with outstanding rate capability (at a high current density of 10 A g −1 , the reversible capacity is 96 mAh g −1 ), and the reversible capacity remains at 79 mAh g −1 after 2500 cycles at 5 A g −1 . These results demonstrate the favorable efficacy of specially designed organic small molecule structures in lithium-ion batteries.