Effect of impurity ions on electrochemical super-capacitive properties of amorphous hydrated ruthenium oxide

Amorphous hydrous ruthenium oxide was prepared by a chemical precipitation method. Two ruthenium oxide samples with different contents of Na and CI impurities were obtained by changing the number of times for washing sediments with distilled water.The experiment results showed that the Na and CI impurities exist as hydrated Na~+ and hydrated CI~-,respectively.Sample W.5(sufficiently washed 5 times with distilled water during its preparation) has lower content of Na~+ and Cl~+ impurities in comparison with sample W_1(insufficiently washed once with distilled water during its preparation).Cyclic voltammetric measurements indicate that the specific capacitance and power performance of W.5 are all higher than that of W_1.Hydrated Na~+ and CI~- impurities not only decrease the specific capacitance of ruthenium oxide,but degrade the power performance.The reason for the deleterious effect of hydrated Na~+ and Cl~- impurities on the super-capacitive properties is discussed.