Highly Flexible Self-Assembled V₂O₅ Cathodes Enabled by Conducting Diblock Copolymers

摘要

Mechanically robust battery electrodes are desired for applications in wearable devices, flexible displays, and structural energy and power. In this regard, the challenge is to balance mechanical and electrochemical properties in materials that are inherently brittle. Here, we demonstrate a unique water-based self-assembly approach that incorporates a diblock copolymer bearing electron- and ion-conducting blocks, poly(3-hexylthiophene)- block -poly(ethyleneoxide) (P3HT- b -PEO), with V₂O₅ to form a flexible, tough, carbon-free hybrid battery cathode. V₂O₅ is a promising lithium intercalation material, but it remains limited by its poor conductivity and mechanical properties. Our approach leads to a unique electrode structure consisting of interlocking V₂O₅ layers glued together with micellar aggregates of P3HT- b -PEO, which results in robust mechanical properties, far exceeding the those obtained from conventional fluoropolymer binders. Only 5?wt % polymer is required to triple the flexibility of V₂O₅, and electrodes comprised of 10?wt % polymer have unusually high toughness (293?kJ/m3) and specific energy (530?Wh/kg), both higher than reduced graphene oxide paper electrodes. Furthermore, addition of P3HT- b -PEO enhances lithium-ion diffusion, eliminates cracking during cycling, and boosts cyclability relative to V₂O₅ alone. These results highlight the importance of tradeoffs between mechanical and electrochemical performance, where polymer content can be used to tune both aspects.