Hefei Research Institute Makes Progress in Research of Flexible Supercapacitors

(a) Preparation process flow chart; (b) Three-dimensional stacked interdigitated electrode side-view SEM image; (c) Surface capacitance density map of different layer three-dimensional stacked interdigital electrodes at different surface current densities; ( d) Cyclic voltammogram of the device at a 90° bend angle (the inset is an optical photograph of the device at a 90° bend angle).

Recently, the research team of Ye Naihui, a researcher at the Department of Micro-nano Technology and Devices of the Institute of Solid State Physics, Chinese Academy of Sciences, Hefei Institute of Materials Science, has made new progress in the research of flexible supercapacitors. The relevant results were published in the Small Journal (Small, 2016, 12, 3059). –3069).

Flexible wearable and portable electronic devices require that the energy-supply devices that drive their operation not only provide sufficient power density and energy density but also have good flexibility. Supercapacitors have high power density, cycle stability and fast charge-discharge characteristics. They are very promising energy-supply devices. However, their low energy density has limited their practical application. Therefore, how to further increase the energy density of the supercapacitor and make it flexible is currently a hot topic in the research field of supercapacitors.

Manganese dioxide is a tantalum capacitor material with a high theoretical specific capacity (1370 F g−1) and is very promising for the preparation of high energy density supercapacitors. However, its poor intrinsic conductivity (10−5-10−6 S cm−1) makes it impossible to increase its electrical storage capacity simply by increasing the thickness of the active material, which seriously hinders its application in high energy density supercapacitors. The researchers of the research group prepared a kind of dioxide on a flexible PET substrate based on the previously developed interdigital electrode laser printing technology (J. Mater. Chem. A, 2014, 2, 20916-20922) combined with electrodeposition technology. A manganese-based three-dimensional laminated interdigitated electrode was used, and a flexible supercapacitor was further prepared using this electrode. The three-dimensional stacked interdigitated electrode configuration can effectively increase the contact area between the manganese dioxide and the gold electrode, overcome the bottleneck problem of poor conductivity of the manganese dioxide, and does not increase the electrode area through superimposition in the Z-axis direction. Under the conditions, the overall thickness of the electrode active material is effectively increased, and the surface capacitance density of the device is increased. Through this electrode structure design, the obtained flexible supercapacitor can reach a maximum surface capacitance density of 11.9 mF cm-2, and theoretically can obtain a higher surface capacitance density through further electrode superposition.

In addition, the research team was invited to write a review article on micro-capacitors (Energy Storage Materials, 2015, 1, 82–102).

The above research work was funded by the National Natural Science Foundation of China and the International Team Project of the Chinese Academy of Sciences.