Electrochemical oxidation of π-π coupling organic cathode for enhanced zinc ion storage

Organic materials typically present low rate performance and limited cycling durability due to the structural destruction and dissolution during electrochemical processes, which greatly hinders their application as promising cathodes for aqueous rechargeable zinc-ion batteries (ZIBs). Here, a strategy of in situ electrochemical oxidation with π-π interaction coupling between graphene and 2,3,6,7,10,11-Hexahydroxytriphenylene (HHTP) stabilizes the composite structure, rendering it a very promising organic composite cathode (named as GH) for ZIBs. More explicitly, the hydroxyl groups of HHTP are in-situ electrochemically transformed into carbonyl groups to form the redox-active sites, in which π-π interactions with graphene urges the highly reversible coordination/incoordination between zinc ions and the GH cathode. Further, such a GH cathode shows a specific capacity of 225 mAh g−1 at 0.05 A g−1 with a high capacity retention of 90% at 10 A g−1 after 7000 cycles, demonstrating high rate and cycle stability are achieved during the discharge/charge process. Thereby, this work provides a novel strategy for engineering an organic composite cathode which corrects the low rate and unstable cycling property for effective use in ZIBs.