Renewable energy and environmental preservation are two grand challenges in our society today. To address these two challenges, increasing demands have been focused on energy storage devices made of green and biodegradable materials. For instance, supercapacitors have been attracting attention owing to their recorded high-performance with the ability to enhance low-power electronics and various other high-power technical and military applications. The performance of these devices can be evaluated via their electrochemical properties with respect to the electrolyte, the active electrode materials, polarization resistance, kinetic diffusion, as well as their charge storage mechanisms. Biomaterials make excellent candidates as active materials for electrodes in supercapacitors. This is attributed to their remarkable properties and their unique structural morphology. Since most of these biomaterials are processed from waste, they also help in waste mitigation while providing high-performing but safe and sustainable technology. Biomaterials are bio-degradable, eco-friendly, and low-cost materials. Current state-of-the-art plant-based electrodes have problems of poor electrochemical performance, low reliability, and high manufacturing cost that pose major limitations in their use in flexible supercapacitors. In this research, a novel microwave irradiation synthesis is used to produce a high-performing electro-active lignin-based biomaterial. An anode electrode has been designed by depositing MnO2&nbsp;particles on lignin-based materials&nbsp;with aluminum foil as the substrate.&nbsp;MnO2 particles are deposited on these lignin-based materials to impart pseudo-capacitance property. These electro-active MnO2&nbsp;decorated materials were coated on the Al substrate and used as an anode. An&nbsp;AC-based electrode was employed as the cathode. Commercial-grade white paper coated with the&nbsp;electrolyte was used as a separator. A quasi-solid-state supercapacitor was assembled using a polymer-based gel electrolyte of PVA/H3PO4. The separator was sandwiched between the two electrodes to form a coin cell.&nbsp;&nbsp;Scanning electron microscopy or SEM&nbsp;and Energy dispersive x-ray&nbsp;spectroscopy or EDS were performed in order to study the morphology, porosity, and polydispersity of the lignin-based matrix. Cyclic voltammetry (CV) was employed to study the polarization resistance of the system. The cyclic charge-discharge (CCD) was performed to observe cyclic performance and the electrochemical impedance spectroscopy (EIS) test was run to study the interfacial resistances. The assembled quasi-solid-state&nbsp;supercapacitor exhibited a specific capacitance of 26 mF/g after 1500 cycles. At 0.1 a/g, it exhibited a high&nbsp;capacitance retention of ~85% which is 10%&nbsp;higher than the performance exhibited of&nbsp;MnO2&nbsp;particles synthesized using&nbsp;similar methods. This work provides new insights into the synthesis of low-cost and scalable plant-based flexible supercapacitors.&nbsp;

Microwave Synthesis of Plant-Based Supercapacitor Electrodes for Flexible Electronics

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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