Enthalpic and Entropic Contributions to Fast Lithium Ion Conduction in Solid-State Aqueous Polymer Electrolytes

초록

Solid-state aqueous polymer electrolytes (SAPEs), a mixture of hydrophilic polymers and an appropriate amount of water, can produce high Li-ion conductivity while maintaining a solid state. Also, they can overcome the limitations of normal solid electrolytes. This study reports that the very high SAPE ionic conductivity (similar to 10 mS/cm at T = 298.15 K) originates from a low energy barrier (similar to 0.28 eV) closely correlated with water-filled ion passages in the medium. The low energy barrier is ascribed to a considerable reduction of the enthalpic barrier due to water addition despite a growth of the entropic barrier incurred by the negative nature of entropy change across water tubes. The extremely high ionic conductivity, coupled with an exceptionally low energy barrier, provides a unique advantage to SAPEs over conventional solid electrolytes.

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