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.

Automated summary

Electrochemical supercapacitors filled with quasi-solid-state potassium ion electrolyte demonstrate a wide working voltage window, high volumetric capacitance, and low equivalent series resistance. By transferring the best coin cell findings to a pouch cell, the study reveals that these supercapacitors are highly flexible and robust, suitable for further development in wearable and bendable devices.