Visualizing Interfacial Charging Activity of Bipolar Organic Electrodes in Proton Batteries

Rechargeable batteries are utilized in various areas such as electric vehicles, portable devices, and grid-scale energy storage. Organic compounds are emerging as promising cathode materials due to their light weight, low cost, safety, and high energy density. Their applications in proton batteries present a promising alternative to conventional batteries. The charging rate of a battery, a crucial parameter affecting its performance and usability, is determined by the kinetics of the electrochemical reaction between the organic materials and electrolyte ions. In this study, we conducted an electrochemical investigation of a bi-functional organic electrode material synthesized from the hydrocondensation reaction of diphenylbenzene-1,4-diamine (DPA) and perylenetetracarboxylic dianhydride (PTCDA). Scanning electrochemical cell microscopy (SECCM) was employed to examine the local reactivity of the organic electrode during the charging/discharging process. High-resolution electrochemical mapping allowed us to visualize the interfacial charging activity across the sample surface. Localized cyclic voltammetry measurements revealed interfacial charging kinetics at a single particle level. Our SECCM results with various electrolytes indicated the critical role of anions in determining electrode reactivity. Specifically, perchlorate ions exhibited the fastest charging rates, while chloride ions showed the slowest. The insights gained from our nanoscale measurements will guide the design of fast-charging aqueous battery systems.