Identification of Al–dtpa–PO4 Ternary Complex Inhibiting Hydration of Alumina Electrodes in Electrolytic Capacitors



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A novel aluminum complex that inhibits hydration-related deterioration of the alumina electrode in electrolytic capacitors has been isolated. The complex forms ternary complexes with phosphate ions and protects the electrode surface by forming a phosphate-ion monolayer. The ternary complex is essential to maintain a constant phosphate-ion concentration in the capacitor electrolytic solution, to protect the electrode for >10 000 h at 105 °C.