<scp>SPEEK</scp> / <scp>CNCs</scp> Composite Membranes for Electrochemical Hydrogen Compressors

ABSTRACT Developing durable and high‐performance proton exchange membranes with low hydrogen crossover is critical for advancing electrochemical hydrogen compressors (EHCs) technology. Here we report the properties of SPEEK/CNCs composite membranes reinforced with cellulose nanocrystals (CNCs) for the electrochemical compression systems. The physicochemical properties, including the morphology of composite membranes, water uptake ( W up ), mechanical strength, ion exchange capacity (IEC), and proton conductivity ( σ H +), were evaluated. The composite membrane with 3 wt% CNCs exhibited a tensile strength of 26 MPa, which is approximately 1.9 times that of pristine SPEEK (13.7 MPa) and 1.5 times higher than that of Nafion 117 (17.6 MPa). The proton conductivity of this membrane reached 0.209 S cm −1 at 90°C, the highest among all evaluated membranes. The performance of EHCs was tested for voltage, compression time, and energy efficiency at pressures up to 5 MPa. Incorporation of nanocellulose crystals (CNCs) into SPEEK membrane resulted in better performance in energy consumption and energy efficiency with shorter compression time in EHC system. In addition, the composite membranes showed low hydrogen back‐diffusion loss.