Engineering electrode/electrolyte interfacial properties of nanotube arrays for high-capacitance supercapacitors

In this study, the effect of imbibition-induced electrolyte wettability over charge carrier density and hence the increase in electric double layer is investigated for morphology-controlled TiO2 nanotube arrays. The nanotube morphology brings in good control over change in surface energy that induces electrolyte wettability. Electrolytes of HCl, KCl, and NaCl were utilized to determine surface energy, surface wettability, and electrochemical studies. The percentage of electrolyte imbibition inside nanopores varies in the order of HCl > KCl > NaCl. The double-layer formation is higher for highly wettable surfaces and is dependent on the percentage of electrolyte imbibition inside nanotube pores. From the observations, it is deduced that the storage performance of nanotube electrodes can be markedly increased by enhancing the molar conductivity and ionic mobility of electrolyte. An areal capacitance of 14.9 mF/cm(2) is observed for HCl electrolyte-based supercapacitor. In addition, the cationic radius of electrolyte influences the stability of electrode with a capacitance retention of 87%.

Automated summary

The study investigated the effect of imbibition-induced electrolyte wettability on charge carrier density and electric double layer in TiO2 nanotube arrays. Different electrolytes were used to study the surface energy, wettability, and electrochemical properties. The results showed that improving the molar conductivity and ionic mobility of electrolyte can significantly enhance the storage performance of nanotube electrodes. Additionally, the cationic radius of electrolyte was found to influence the stability of electrodes, with HCl electrolyte showing a high areal capacitance in supercapacitors.