Robust, Freestanding, And Bendable Multi-Walled Carbon Nanotube Buckypapers As Electrode Materials For Quasi-Solid-State Potassium-Ion Supercapacitors

We report here on the performance of quasi-solid-state potassium ion electrolyte filling electrochemical supercapacitors. The electrolyte is composed of aqueous-based polyvinyl alcohol with potassium and sulfate ions. This electrolyte is first investigated filling the coin cells with two identical multi-walled carbon nanotube buckypapers as the electrode materials, and later, it was analyzed in a pouch cell. Our electrochemical results, obtained from different techniques, show that the cell's working voltage window is as wide as 1.6 V, yielding a volumetric capacitance of 18 F cm-3, and equivalent series resistance smaller than 2.5 omega. We prepare a pouch cell with our best coin cell findings to investigate the cell's mechanical behavior. Our findings showed that quasi-solid-state potassium ion-based supercapacitors are highly flexible and robust, thus encouraging further investigation on the development of flexible supercapacitors to be applied on various wearable and bendable devices.