A crystalline dihydroxyanthraquinone anodic material for proton batteries

As a class of redox-active compounds, anthraquinones (AQs) have been investigated in rechargeable metallic ion batteries. In this work, it is found that protons (H+) can be reversibly intercalated and deintercalated in crystalline 2,6-dihydroxyanthraquinone (DHAQ) at a potential of -0.21 V vs. Ag/AgCl in acidic solution and exhibits a specific capacity of 110 mAh g(-1). This unique property is leveraged in a rechargeable proton battery system with a DHAQ anode and an Mn2+ cathode. During battery cycling, a morphology evolution from particulate DHAQ into centimeter-scale nanofibers is observed. It is revealed that the evolution of morphology stems from a realignment of the DHAQ molecule. The quinone proton battery delivers an equilibrium voltage of 1.1 V, and the capacity retention rate could be as high as 100% after 2600 cycles. This study showcases a unique proton (de)intercalation chemistry in crystalline AQ and demonstrates the viability of the organic proton battery system. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This study demonstrates the reversible intercalation and deintercalation of protons in crystalline 2,6-dihydroxyanthraquinone (DHAQ), which is utilized in a rechargeable proton battery system with high capacity retention rate. Furthermore, the morphology evolution from particulate DHAQ into centimeter-scale nanofibers is observed during battery cycling.