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Microsupercapacitor Aging with an Electroreflectance Method

posted Jun 14, 2013, 8:44 AM by Timothy Fisher   [ updated May 4, 2015, 6:31 PM by Tim Fisher ]

Student: Kimberly Saviers

Faculty: Tim Fisher, Ali Shakouri

Sponsor: AFOSR

Summary: Supercapacitors bridge the gap between traditional capacitors and batteries in that they can achieve both high power density and high energy density in one device. Because they are new devices in the marketplace, it is imperative that their aging behavior is thoroughly understood. Microsupercapacitors were fabricated and evaluated over millions of charge/discharge cycles using an electroreflectance method in order to understand their aging behavior. The devices were constructed of gold electrodes by traditional photolithography etching techniques. Eight interdigitated fingers comprise each electrode with separation on the order of microns. The devices were continuously charged and discharged while capacitance and electroreflectance signals were periodically recorded. The electroreflectance technique measures light reflected from the device during the charge/discharge cycle. Because charge accumulates in the device, the reflectivity property of the electrodes changes throughout the charge/discharge cycle. This allows for knowledge of the spatial resolution of the charge accumulation in the device. Here, this information is used to understand the evolution of charge accumulation behavior over millions of cycles.

Representative Paper: http://onlinelibrary.wiley.com/doi/10.1002/elan.201300238/abstract