Among reported investigations, only a handful studies were carried out to understand the equilibrium potential of HER in concentrated electrolyte solutions. It has been suggested that significant parts of the concentration-dependent shift in the open circuit voltage (OCV) for both LiCl (∼400 mV) and LiTFSI (∼250 mV) electrolytes as measured by ion selective electrode originate from the changes in liquid junction potentials. Despite of that, this study suggested that protons are indeed created when increasing the salt concentration. This agrees with a previous report showing that the pH value of LiTFSI solutions drops from 6.5 to 2.4 when increasing the salt concentration within the same range from 1 m to 20m. Similarly, the study of ref. found that the effective concentration of protons increases upon reaching high LiCl concentrations. On the other hand, a recent computational study with density functional theory-based molecular dynamics (DFTMD) simulations showed that the reduction potential of the TFSI anion is insensitive to the salt concentration, while the water reduction potential moves down to a significantly lower value which indicates a reduced proton reactivity. Therefore, it is unclear whether the thermodynamic reversible potential for the HER would go up or down with the increase of salt concentration.