Fabrication and Characterization of Flexible Solid-State MIM Supercapacitor with Inkjet-Printing of Stacked Ag NP and Polymer Dielectric Layers

Abstract

Electrification of vehicles and energy-storage needs of renewables and robotic devices including wearables, implantables, drones, and wireless sensors demands energy storage solution that is not achievable with current battery technology. In this paper, we present the proof-of-concept results of inkjet-printed (IJP) flexible supercapacitors to store energy and power devices for wearables and implantable, as well as other energy storage needs. We have developed a patent-pending technique of stacked Metal-Insulator-Metal (MIM) parallel plate capacitors to form supercapacitor with high energy density. The flexible supercapacitor was fabricated on a thin 25 µm flexible polyimide (PI) film. We have used silver (Ag) nanoparticle (NP) ink for printing the conductive layer and a polymer Poly(4-vinylphenol) ink for printing dielectric layer to fabricate insulation between metal plates. The area of the supercapacitors was 100 mm². Six coatings of PVP dielectric were printed for proper insulation between two successive metal layers. The measured capacitance of a single MIM capacitor was 996 pF. The measured capacitance of two-stacked MIM capacitors on the same footprint was 1.98 nF. The thickness of two stacked MIM capacitor was 22.3 µm. By stacking more MIM capacitors on the same footprint, supercapacitors can be fabricated that can achieve high energy storage capability within a small footprint, weight, and volume. This IJP supercapacitor, which is flexible yet solid-state with high-performance and safe for long-term use, can play a significant role in wearables, implantable, drones, renewable energy storage, and electric vehicles.