Catalysis

Engineering

Polymer chemistry

Nafion

Electrochemistry

Materials science

Flow battery

Phosphotungstic acid

Biochemistry

Inorganic chemistry

Chemical engineering

Vanadium

Faraday efficiency

Physical chemistry

Redox

Nanotechnology

Organic chemistry

Membrane

Carbon nanotube

Conductivity

Chemistry

Electrode

Electrolyte

Ether

Journal of Membrane Science

A hybrid membrane of sulfonated poly(ether ether ketone)/polydopamine-coated carbon nanotubes loaded phosphotungstic acid (S/DCNTs-HPW) is proposed for vanadium redox flow battery (VRFB). With the DCNTs-HPW nanofillers as the proton donor and acceptor, a high proton conductivity and low vanadium ions permeability of the S/DCNTs-HPW hybrid membranes is demonstrated owing to the formed acid-base interaction. Specifically, S/DCNTs-HPW-1 gives higher ion selectivity (25.4 × 103 S min cm−3) than that of pristine SPEEK (4.3 × 103 S min cm−3) and Nafion 117 (4.0 × 103 S min cm−3). Cell utilizing S/DCNTs-HPW-1 reveals excellent coulombic efficiency (98.2–99.4%) and energy efficiency (89.5–69.0%) under the current density of 50–160 mA cm−2, and a 34.5% charge capacity retention under 100 cycles is achieved based on the excellent membrane structure and chemical stability. The S/DCNTs-HPW-1 membrane shows a self-discharge time of 576 h, which is longer than that of the Nafion 117 membrane (23 h). Thus, the S/DCNTs-HPW hybrid membranes are suggested for potential use as alternative PEMs in the VRFB system.

Hybrid proton exchange membrane of sulfonated poly(ether ether ketone) containing polydopamine-coated carbon nanotubes loaded phosphotungstic acid for vanadium redox flow battery