Unleashing high-efficiency proton storage: Innovative design of ladder-type organic molecules

Abstract

The architectural design of redox-active organic molecules and the modulation of their electronic properties significantly influence their application in energy storage systems within aqueous environments. However, these organic molecules often exhibit sluggish reaction kinetics and unsatisfactory utilization of active sites, presenting significant challenges for their practical deployment as electrode materials in aqueous batteries. In this study, we have synthesized a novel organic compound (PTPZ), comprised of a centrally symmetric and fully ladder-type structure, tailored for aqueous proton storage. This unique configuration imparts the PTPZ molecule with high electron delocalization and enhanced structural stability. As an electrode material, PTPZ demonstrates a substantial proton-storage capacity of 311.9 mAh g⁻¹, with an active group utilization efficiency of up to 89% facilitated by an 8-electron transfer process, while maintaining a capacity retention of 92.89% after 8000 charging-discharging cycles. Furthermore, in-situ monitoring technologies and various theoretical analyses have pinpointed the associated electrochemical processes of the PTPZ electrode, revealing exceptional redox activity, rapid proton diffusion, and efficient charge transfer. These attributes confer a significant competitive advantage to PTPZ as an anode material for high-performance proton storage devices. Consequently, this work contributes to the rational design of organic electrode materials for the advancement of rechargeable aqueous batteries.