Effect of Structural Ordering on the Charge Storage Mechanism of p-Type Organic Electrode Materials

Abstract

Understanding the properties that govern the kinetics of charge storage will enable informed design strategies and improve the rate performance of future battery materials. Herein, we study the effects of structural ordering in organic electrode materials on their charge storage mechanisms. A redox active unit, N,N'-diphenyl-phenazine, was incorporated into three materials which exhibited varying degrees of ordering. From cyclic voltammetry analysis, the crystalline small molecule exhibited diffusion-limited behavior, likely arising from structural rearrangements that occur during charge/discharge. Conversely, a branched polymer network displayed surface-controlled kinetics, attributed to the amorphous structure which enabled fast ionic transport throughout charge/discharge, unimpeded by sluggish structural rearrangements. These results suggest a method for designing new materials for battery electrodes with battery-like energy densities and pseudocapacitor-like rate capabilities.