Efficient electrochemical hydrogen compression based on high-crystallinity polymeric membrane electrolytes

Proton exchange membranes (PEMs) play a crucial role in electrochemical hydrogen compression (EHC), where the compression ratio is only limited by the back diffusion of molecular hydrogen through the PEM. This study significantly limited back diffusion by adopting a high crystallinity PEM with high proton conductivity, based on the non-fluorinated polymer polyvinyl alcohol (PVA). This polymer has an extremely low hydrogen permeability of 0.036 Barrer, and when doped with various metal oxides nanoparticles (MnO 2 , Fe 3 O 4 and V 2 O 5 ) enhanced the proton conductivity by orders of magnitude above the base polymer. The best performing PVA-EHC was with 0.1 wt% V 2 O 5 , which achieved an impressive compression ratio of 19.5, and an efficiency above 60%, based on an applied potential of 0.1 V. This compression ratio performance was retained over 48 h, demonstrating the stability of the PVA membranes and highlights the potential of this technology in the hydrogen economy. • Electrochemical hydrogen compression (EHC) ratios above 19.5 were achieved within a single cell. • PVA composite membranes doped with metal oxides were used as the proton exchange membrane. • Proton conductivity of PVA membranes were improved by optimising metal oxide concentration. • PVA membranes had extremely low hydrogen permeability enabling the high compression ratios. • PVA composite membrane EHC achieved an efficiency >61%.