A dual redox-active and robust polymer enables ultrafast and durable proton-storage capability

Aqueous proton batteries (APBs) offer a viable and attractive option in the field of affordable and sustainable energy solutions. Organic polymers are highly favored due to their environmentally friendly manufacturability and malleable molecular configurations, making them suitable materials for constructing APB electrodes. Nonetheless, their currently limited capacity for proton-associated redox reactions poses a challenge to the widespread usage. Herein, we have developed a highly redox-active organic polymer (PTA) tailored for APB applications. The inclusion of dual redox-active moieties in the extended π-conjugated frameworks not only enhances the redox activity and refines the electronic properties, but also ensures the high structural integrity of the PTA polymer. When used as an electrode, the PTA polymer has a notable ability to store protons, with a large capacity of 213.99 mA h g−1 at 1 A g−1 and exceptional long-term stability, as evidenced by retaining 94.6% of its initial capacity after 20,000 cycles. In situ techniques alongside theoretical calculations have unveiled efficient redox processes occurring at C=N and C=O redox-active sites within the PTA electrode upon proton uptake/removal. Furthermore, a soft-package APB device has been assembled with impressive electrochemical behaviors and excellent operational lifespan, accentuating its significant promise for real-world deployment.