Novel intrinsic microporous binders in the cathode catalyst layer for high-performance alkaline water electrolysis

Abstract

Anion exchange membrane water electrolysis (AEMWE) garners significant attention. However, systematic studies on the binder structure and content are scarce. Therefore, we report two novel quaternized polymers of intrinsic microporosity with pyrrolidinium and piperidinium cations (referred to as QPIM-Py and QPIM-Pi) as binder materials. Additionally, the effect of the microporosity structure on the AEMWE performance is compared to that of the control binder without microporosity (poly(p-terphenyl N,N-dimethylpiperidinium) referred to as PAP-TP-85, 85 is the molar ratio between N-methyl-4-piperidone and aryl monomers). The hydrogen permeabilities of QPIM-Py and QPIM-Pi membranes are found to be 60.5 and 32.4 barrer, which are significantly higher than that of the PAP-TP-85 (4.07 barrer). Moreover, the surface area of the QPIM-based catalyst layer (CL) is substantially higher than that of the control CL. Finally, with home-made PAP-TP-85 membrane and the aforementioned binders in the CL, it is demonstrated that the binder structure in the cathode CL has a considerable impact on the AEMWE performance. The AEMWE with QPIM-Py-10 % binder achieves the best performance, with a current density of 2000 mA/cm² at a voltage of 2.04 V. Furthermore, the CL with modified binder demonstrates a much higher performance than that with microporosity-free binder in AEMWE.