An advanced large-porosity porous channel structure electrode for vanadium redox flow batteries

Electrospinning technology has been extensively used to prepare electrodes for vanadium redox flow batteries (VRFBs). Nevertheless, electrospinning carbon nanofibers (ECNFs) electrodes suffer from low porosity and poor permeability, hence significantly hindering mass transport. To solve this critical issue, a new approach to prepare porous channel electrodes with large porosity based on electrospinning technology is proposed. The electrode is fabricated by electrospinning of polyacrylonitrile and poly (methyl methacrylate) (PMMA) solutions. PMMA not only acts as a sacrificial phase to form a porous channel structure inside the fibers, but also interconnects the fibers, which significantly increases the inter-fiber pore space and enhances the mass transfer performance. Electrochemical characterizations indicate that the electrodes have a remarkably elevated electrochemical specific surface area and outstanding electrochemical performance. Owing to the well-designed large-porosity porous channel structure of the electrode, the energy efficiency of the VRFB equipped with this electrode is 74.45% at 300 mA cm −2 and 81.03% at 200 mA cm −2 , and the battery can be continuously charged and discharged for more than 1200 cycles, which demonstrates a long-term cycling stability of the electrode. All of these indicate that this efficient and durable method for propagating electrode has broad application prospects. • Prepared an electrode with porous channel structure. • The electrodes exhibit enlarged pores while retaining large specific surface areas. • The design greatly improves activity of electrodes. • The prepared electrodes enable a significant enhancement in the battery performance.