Ice as Solid Electrolyte To Conduct Various Kinds of Ions

Water, considered as a universal solvent to dissolve salts, has been extensively studied as liquid electrolyte in electrochemical devices. The water/ice phase transition at around 0 °C presents a common phenomenon in nature, however, the chemical and electrochemical behaviors of ice have rarely been studied. Herein, we discovered that the ice phase provides efficient ionic transport channels and therefore can be applied as generalized solid-state ionic conductor. Solid state ionic conducting ices (ICIs) of Li⁺, Na⁺, Mg²⁺, Al³⁺, K⁺, Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, and Zn²⁺, frozen from corresponding sulphate solutions, exhibit ionic conductivities ranging from ≈10⁻⁷ S cm⁻¹ (Zn²⁺) to ≈10⁻³ S cm⁻¹ (Li⁺) at temperatures spanning from −20 °C to −5 °C. The discovery of ICIs opens new insight to design and fabrication of solid-state electrolytes that are simple, inexpensive, and versatile.