Proton Coordination Chemistry in Pyrene-based Anode for Ultralong-life Aqueous Proton Batteries

Sustainable and safe aqueous proton batteries (APBs) have attracted significant attention owing to the unique “Grotthuss mechanism”. Although organic small molecules with stable and adjustable framework are promising electrode materials, their easy-dissolution in electrolyte and unsatisfactory intrinsic conductivity cripple the broader application in APB devices. Herein, the 2,7-diammonio-4,5,9,10-tetraone (PTO-NH3+) with the stable intermolecular hydrogen-bond networks is designed via the in-situ electrochemical reduction strategy, while the optimized molecule structure endows low charge transport barriers, high chemical reactivity, and prominent charge affinity. The fast kinetics of proton coordination/de-coordination behavior in PTO-NH3+ electrode is corroborated by ex-situ characterization techniques and theoretical calculations. As a result, the robust four-step 4e- H+ coordination with PTO-NH3+ electrode achieves an excellent rate performance (214.3 mAh g-1 at 0.05 A g-1, 112.9 mAh g-1 at 40 A g-1), along with a long lifespan (10000 cycles). These findings shed light on the further avenue towards advanced proton batteries.