A Redox-Active Covalent Organic Framework with Highly Accessible Aniline-Fused Quinonoid Units Affords Efficient Proton Charge Storage

Owing to their intrinsic safety and sustainability, aqueous proton batteries have emerged as promising energy devices. Nevertheless, the corrosion or dissolution of electrode materials in acidic electrolytes must be addressed before practical applications. In this study, a cathode material based on a redox-active 2D covalent organic framework (TPAD-COF) with aniline-fused quinonoid units featuring inherently regular open porous channels and excellent stability is developed. The TPAD-COF cathode delivers a high capacity of 126 mAh g-1 at 0.2 A g-1, paired with long-term cycling stability with capacity retention of 84% after 5000 cycles at 2 A g-1. Comprehensive ex situ spectroscopy studies correlated with density functional theory (DFT) calculations reveal that both the -NH- and C=O groups of the aniline-fused quinonoid units exhibit prominent redox activity of six electrons during the charge/discharge processes. Furthermore, the assembled punch battery consisting of a TPAD-COF//anthraquinone (AQ) all-organic system delivers a discharge capacity of 115 mAh g-1 at 0.5 A g-1 after 130 cycles, implying the potential application of the TPAD-COF cathode in aqueous proton batteries. This study provides a new perspective on the design of electrode materials for aqueous proton batteries with long-term cycling performance and high capacity. A redox-active 2D covalent organic framework (TPAD-COF)-based cathode with aniline-fused quinonoids for proton batteries is developed. The assembled TPAD-COF//AQ all-organic proton battery exhibits excellent cycling performance. Comprehensive ex situ spectroscopy studies correlated with theoretical calculations reveal that both the NH and C=O groups of the aniline-fused quinonoids exhibit prominent redox activity of six electrons during the charge/discharge processes.image

Automated summary

A cathode material based on a 2D covalent organic framework (TPAD-COF) with regular open porous channels and excellent stability is developed. The TPAD-COF cathode shows high capacity and cycling stability. The NH and C=O groups in the aniline-fused quinonoids exhibit prominent redox activity. The TPAD-COF cathode can be potentially applied in aqueous proton batteries.