As the world shifts towards a more sustainable future, the development of advanced electrochemical devices, such as rechargeable batteries with higher energy densities and efficient electrodeposition capabilities, has become increasingly crucial. In recent years, ultra-concentrated electrolyte solutions, where metal salts are dissolved at concentrations two to three times higher than those in a single solvent, or mixtures where metal salts are excessively dissolved in a single solvent, have gained attention as new electrolyte solutions.