Facile synthesis of phenazine-conjugated polymer material with extraordinary proton-storage redox capability

Aqueous proton batteries (APBs) embody a compelling alternative in the realm of economical and reliable energy technologies by virtue of their distinctive “Grotthuss mechanism”. Sustainable production and adjustable molecular structure make organic polymers a promising choice for APB electrodes. However, inadequate proton-storage redox capability currently hinders their practical implementation. To address this issue, we introduce a pioneering phenazine-conjugated polymer (PPZ), synthesized through a straightforward polymerization process, marking its debut in APB applications. The inclusion of N-heteroaromatic fused-ring in the extended π-conjugated framework not only prevents the dissolution of redox-active units but also refines the energy bandgap and electronic properties, endowing the PPZ polymer with both structural integrity and enhanced redox activity. Consequently, the PPZ polymer as an electrode material achieves a remarkable proton-storage capacity of 211.5 mAh/g, maintaining a notable capacity of 158.3 mAh/g even under a high rate of 8 A/g with a minimal capacity fade of merely 0.00226% per cycle. The rapid, stable and impressive redox behavior is further elucidated through in-situ techniques and theoretical calculations. Ultimately, we fabricate an APB device featuring satisfactory electrochemical attributes with an extraordinary longevity over 10,000 cycles, thereby affirming its auspicious potential for eminent applications.