A rocking-chair type all-organic proton battery operated at ultralow temperature

Abstract

Aqueous proton batteries have garnered significant interest owing to their cost-effectiveness and enhanced safety. However, achieving all-organic rocking-chair proton batteries remains a challenge due to the lack of suitable organic electrode materials in acid electrolytes. This study presents an all-organic rocking-chair proton battery employing a diquinoxalino [2,3-a:2′,3′-c] phenazine (HATN) anode paired with a 2,6-dihydroxynaphthalene (2,6-DHN)@CMK-3 cathode, operating in 9.5 m H₃PO₄ electrolyte. Its working mechanism includes reversible –C–O–H/–CO conversion at the cathode coupled with –CN/–C–N–H conversion at the anode. Thanks to its rapid reaction kinetics, this proton battery exhibits a reversible discharge capacity of 101 mAh g⁻¹ at 1 A g⁻¹, a satisfactory energy density of 61 Wh kg⁻¹, and an exceptional cycling stability beyond 6000 cycles. Notably, benefiting from the low freezing point of the 9.5 m H₃PO₄ electrolyte, this proton battery sustains robust rate capability and stable cycling down to −50 °C, highlighting its suitability for operation under cold conditions.