Paper TF-ThP26
Toward Ultra-fast Switching Speed Electrochromic Supercapacitor

Thursday, October 24, 2019, 6:30 pm, Room Union Station B

As one of the most promising energy storage devices, supercapacitors have been widely adopted in different fields due to their high power density and long service life. However, with the rapid development of intelligent electronic products, there is an urgent need to construct multifunctional supercapacitors to broaden the range of applications. Integration of electrochromism into supercapacitors is one of the innovative approaches to achieve device multifunctionality. An electrochromic supercapacitor can change color reversibly in response to different applied voltages. The instant capacity of the devices can be simply recognized by naked eyes. Implementation of electrochromism to supercapacitors can also prevent device overcharging, leading to a longer device lifetime. Nevertheless, the performance of previously reported electrochromic supercapacitor devices suffers from a slow switch mechanism as well as a low power density, which highlights the need for the electrode structures optimization.

In this report,an electrochromic asymmetrical supercapacitor device (EASD) is developed, which successfully achieves the multifunctional combination of electrochromism and energy storage by adopting polyaniline and tungsten trioxide as the positive and negative electrodes, respectively. In order to improve the device performance, a facile electrochemical activation process is applied to the electrode. The optimized EASD shows a high volumetric energy density of 35.3 mWh/cm³ at a high power density of 1.02 W/cm³ with excellent cycling stability. More importantly, it exhibits a high coloration efficiency of 123.4 cm²/C with an ultra-fast switching speed of 0.4 s / 1.4 s for colored / bleached states, which is one of the fastest switching devices reported so far. Such an EASD shows great potential in the applications of smart windows, smart electronics, and intelligent energy storage.