Thermoregulated polyoxometalate-based ionic-liquid gel electrolytes

Abstract

A series of vanadium-substitutive polyoxometalate-based ionic liquids, [PyPS]₆PW₉V₃O₄₀, [PyPS]₄PW₁₁VO₄₀, [PyPS]₄PMo₁₁VO₄₀ and [PyPS]₇P₂W₁₇VO₆₂, bearing sulfo-group grafted ammonium (PyPS), are transformed to reversible thermal-response gel-type compounds. Interestingly, these gel-type compounds exhibit an obvious increase in their conductivity during the reversible phase transformation, which means that they are a novel series of reversible thermal-response gelation electrolytes. The relationship between the component elements of the polyoxometalate-based ionic liquids and their electrochemical performances has been studied. The Dawson-type compound ([PyPS]₇P₂W₁₇VO₆₂) has a higher conductivity than the Keggin-type one ([PyPS]₄PW₁₁VO₄₀) with the same number of vanadium atoms in the structure. What’s more, the W-containing compounds ([PyPS]₆PW₉V₃O₄₀ and [PyPS]₄PW₁₁VO₄₀) have higher conductivities than the Mo-containing one ([PyPS]₄PMo₁₁VO₄₀).