Flexible Hybrid Electrodes Containing Vanadium Pentoxide (V$_{2}$O$_{5})$ and an Electron- and Ion-Conducting Diblock Copolymer for Energy Storage

Vanadium pentoxide (V$_{2}$O$_{5}$) is a promising cathode material for Lithium-ion batteries due to its high capacity, high energy density, and cost-effectiveness. However, its low lithium-ion diffusion coefficient (10$^{-12}$ - 10$^{-13}$ cm$^{2}$/s), low electronic conductivity (10$^{-2}$ - 10$^{-3}$ S/cm), and severe volumetric changes during cycling have hindered its application in practical devices. One way to address these problems is to design hybrid electrodes that incorporate a second active material. For this purpose, poly(3-hexylthiophene)-\textit{block}-poly(ethylene oxide) (P3HT-$b$-PEO) block copolymer containing electron- and ion-conducting polymer blocks was introduced to a V$_{2}$O$_{5}$ electrode system. Cathodes are prepared by mixing aqueous dispersions of block copolymer, V$_{2}$O$_{5}$, and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and drop casting. The V$_{2}$O$_{5}$ and P3HT-$b$-PEO hybrid electrode showed synergistic results, having improved electrochemical storage performance and mechanical property. We also demonstrated a flexible battery prototype using the P3HT-$b$-PEO/V$_{2}$O$_{5}$ cathode.