Pyridinium functionalized, 2-adamantane containing poly(aryl ether ketone) membranes for use in vanadium redox flow batteries

High-performance membranes are crucial components for high power density, durable vanadium redox flow battery (VRFB). Many cost-effective membranes with high conductivity and good ion selectivity have been developed, but most of these membranes have inadequate stability. To rectify this situation, a new pyridinium functionalized, 2-adamantane containing poly (aryl ether ketone) (Py2-ADMPEK) membranes with high battery performance and excellent stability are developed. Positively charged pyridinium groups are introduced into the rigid, hydrophobic and low swelling adamantane containing backbone. Consequently, the resulting Py2-ADMPEK membrane with a high ion exchange capacity of 2.59 mmol g−1 exhibits water swelling of only 14.5% and low area resistance (0.17 Ω cm2) close to that of Nafion 212 membrane (0.13 Ω cm2)). Furthermore, the Py2-ADMPEK membranes benefit from their limited swelling and the Donnan effect, that produce good selectivity and excellent stability. A VRFB containing a Py2-ADMPEK membrane exhibit very promising battery performance (coulombic efficiency of 98.3%, voltage efficiency of 89.7% and energy efficiency of 88.2% at 80 mA cm−2). Moreover, the Py2-ADMPEK membrane exhibit stable battery performance (more than 2000 cycles at 120 mA cm−2) and excellent chemical stability. [Display omitted] •New 2-adamantane containing membranes with pyridinium groups are prepared.•Py2-ADMPEK membranes exhibit low swelling and low area resistance.•Py2-ADMPEK membrane produce high energy efficiency.•Py2-ADMPEK membranes exhibit high chemical stability.