Enhancing Performance Stability of Electrochemically Active Polymers by Vapor-Deposited Organic Networks

Performance stability of electrochemically active polymers (EAPs) remains one of the greatest and long-standing challenges with regard to EAP-based technologies for a myriad of energy, biomedical, and environmental applications. The performance instability of EAPs originates from their structural alteration under repeated charge-discharge cycling and/or flexing. In this work, a conceptually new "soft confinement" strategy to enhance EAP performance stability, including cyclic and mechanical, by using rationally designed, vapor-deposited organic networks is presented. These chemically cross-linked networks, when in contact with an electrolyte solution, turn into ultrathin, elastic hydrogel coatings that encapsulate conformally the EAP micro-/nanostructures. Such hydrogel coatings allow easy passage of ions that intercalate with EAPs, while simultaneously mitigating the structural pulverization of the EAPs and/or their detachment from substrates. Fundamentally distinct from extensively studied "scaffolding" or "synthetic" approaches to stabilizing EAPs, this soft confinement strategy relies on a postmodification step completely decoupled from the EAP synthesis/fabrication, and enjoys the unique advantage of substrate-independency. Hence, this strategy is broadly applicable to various types of EAPs. The proposed stability enhancement strategy is demonstrated to be effective for a range of EAP systems with differing chemical and morphological characteristics under various testing conditions (repeated charging/discharging, bending, and twisting).