Electroreflectance imaging of gold–H₃PO₄ supercapacitors. Part I: experimental methodology

Abstract

Electroreflectance microscopy is demonstrated as a high-resolution, non-contact method to image dynamic charge distribution in integrated microsupercapacitor structures during fast voltage cycling. Electroreflectance camera images of a gold electrode H3PO4 polymer electrolyte microsupercapacitor reveal time varying charge distribution with submicron spatial resolution, millisecond time resolution, and electroreflectance resolution on the order of 500 nC cm(-2). A model describing changes in the metal electrode's optical constants as a function of free electron concentration shows good agreement with measured electroreflectance. The proposed method can be used for sensitive, non-contact measurements of charge spatial distribution, and defect and performance characterization in electrode-electrolyte microdevices.

Electroreflectance imaging of gold-H3PO4 supercapacitors. Part II: microsupercapacitor ageing characterization

“…Overall, the reflectance change varies linearly with charge accumulation and thus capacitance. 26 The skin layer thickness d was unknown for the reflectance calculations, and hence a parametric variation was performed to minimize the mean square error MSE ref as shown in Fig. 12 for several ageing conditions.…”

“…An electroreflectance method was used to study the distribution of charge in the microsupercapacitor electrodes. The method is described in detail in the companion paper by Maize et al 26 The optical reflectance of the electrodes changes due to the accumulation of electrons in the conduction band, thus resulting in a spatial distribution image of the microsupercapacitor. This measurement was performed with two separate devices: one defect-free and the other showing characteristics of a decreased initial capacitance.…”

“…An equivalent circuit model enables further understanding of the physical phenomenoa occurring in the device, while an electroreflectance model verifies the experimental reflectance results. An abbreviated description of both an electroreflectance and circuit model is included here, while the companion paper 26 provides a full presentation of each model.…”

Laser fabrication of functional micro-supercapacitors

“…This unique design endows it with abundant exposed edges and adjustable separators, which is expected to achieve the ideal capacitance, high energy density and fast ion-transport [14,15].…”

Symmetric All-Solid-State Supercapacitor Operating at 1.5 V Using a Redox-Active Gel Electrolyte

“…In recent years, supercapacitors have emerged to be promising energy storage devices for their fast power delivery, excellent cyclic stability, and low maintenance costs. , The general approach to boost energy density by using pseudocapacitive electrode materials such as transition metal oxides and conducting polymers involves complicated fabrication processes and leads to poor cycle life . Recently, several groups have investigated the possibility of enhancing energy density by introducing redox-active species into the electrolyte.…”