Fast and stable NH4+ storage in multielectron H-bonding-acceptor organic molecules for aqueous zinc batteries†

Abstract

High-capacity small organic compounds are easily dissolved in aqueous electrolytes, resulting in limited cycling stability of Zn-organic batteries (ZOBs). To address this issue, we proposed constructing superstable lock-and-key hydrogen-bonding networks between the 2,7-dinitrophenanthraquinone (DNPQ) cathode and NH₄⁺ charge carriers to achieve ultrastable ZOBs. DNPQ, with its sextuple-active carbonyl/nitro motifs (H-bonding acceptors), was found to be uniquely prone to redox-coupling with tetrahedral NH₄⁺ ions (H-bonding donors) while excluding sluggish Zn²⁺ ions, owing to a lower activation energy (0.32 vs. 0.43 eV). NH₄⁺-coordinated H-bonding electrochemistry overcame the instability of the DNPQ cathode in aqueous electrolytes and enabled rapid redox kinetics of non-metal NH₄⁺ charge carriers. As a result, a three-step 3e⁻ NH₄⁺ coordination with the DNPQ cathode achieved large-current survivability (50 A g⁻¹) and long-lasting cyclability (80 000 cycles) for ZOBs. This work broadens the potential for developing high-performance H-bonding-stabilized organics for advanced ZOBs.