The Polymer Society of Korea

Abstract

Conjugated polymer cathodes are promising candidates for next-generation Li-ion batteries, but their capacity is limited by inactive alkyl side chains. We propose a simple heat-treatment strategy to remove the side chains of a naphthalenediimide (NDI)-based polymer P(NDI2OD-T2). This reduced inactive mass and nearly doubled the specific capacity from 56.3 to 117.0 mAh g⁻¹. It also created a porous structure that improved ion diffusion and capacitive storage. Electrochemical tests showed that the heat-treated electrode maintained stable performance at sub-zero temperatures due to better ion transport and surface storage. At room temperature its crystallinity decreased, lowering conductivity compared to the fresh electrode, but the capacity was still greatly enhanced. These results highlight post-treatment as an effective route to tune the structure–property relationship of conjugated polymer cathodes and enhance the capacity of organic electrodes.