Supercapacitors have been attracting vigorous research interest as promising means of electricity storage due to their high power densities, superhigh cyclic lives, and safe operation, which have shown high value and huge market potential in many areas such as transportation, electric power, communication, national defense, and consumer electronics. Among many research directions, developing an innovative supercapacitor endowed with intelligent features is an exciting assumption, which represents an important way to bring the technology closer to real application. “Intelligent” means that a supercapacitor not only functions as a conventional energy storage device but also interacts with humans without complicated circuit design, for example, one displays the energy information in the form of image or graphics.    

A smart supercapacitor electrode, developed by Dr. Zhao and his colleagues, may serve as a starting point for the future rational design of novel smart supercapacitors. Two commonly used electrochromic materials, W₁₈O₄₉ and polyanline (PANI), were employed as components in this smart supercapacitor electrode. Just as neon signs on our modern streets display information through color contrast of visual graphics, a pattern was designed on the capacitor electrode, with the metal-oxide W₁₈O₄₉ and PANI constituting the pattern and background, respectively, both of which store energy and simultaneously manifest color changes. The pattern color scheme can be employed as immediate indicator of the energy level stored in supercapacitor, bridging electrochromic behaviors with energy storage uses, thes tate of energy can be constantly and visually conveyed through recognizing variations in pattern color schemes during capacitive process. The present study delivers new features and functionalities to conventional supercapacitor devices.    

The research result has been published in Nano Letters (2014, 14, 2150-2156). These works were supported by National Natural Science Foundation of China (grant No. 51372266, 51102274), and Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry.   

Images of the supercapacitor electrode at several typical states demonstrating the stored energy conveyed through pattern color scheme recognition.(Image By SINANO)