Transparent and Flexible Supercapacitors with Networked Electrodes

S. Kiruthika, C. Sow and G. U. Kulkarni
Small 13(40) (2017). DOI: 10.1002/smll.201701906

Transparent and flexible energy storage devices, such as supercapacitors have become increasingly popular as they provide higher power densities than the lithium ion batteries and higher energy densities than the electrolytic capacitors along with additional advantages such as long cycle life and fast charging-discharging rates. In this work, a flexible Au/MnO2 supercapacitor has been fabricated with a visible transparency of 75% and areal capacitance of 3 mF/cm2. The transparent Au wire network-based current collector was obtained using the crackle template method over a membrane separator. The Au wire networks were decorated with high surface area pseudocapacitive MnO2 nanostructures by an electrodeposition process. The fabricated device shows high stability over 5000 charge-discharge cycles in two electrode configuration. In this case, the membrane separator itself was used as a substrate, which allowed the two electrodes to place one over the other rather than making them face each other with a separator in between, as in generally done. Thus, the device brings in the desired transparency and lightweight while additionally exploiting its porous nature in enhancing the interaction of electrolyte with the active material, thereby enhancing the storage capacity. In addition, a solid-state flexible supercapacitor was also fabricated by sandwiching two Au/MnO2 electrodes with gel electrolyte, which shows high flexibility towards very low bending radius. Furthermore, lightweight device has been fabricated on either sides of the separator taking the advantage of porous nature of the separator with no loss in transmittance and capacitance values.

Posted by Chaitali Sow