Rational Formulation of Graphene Nanocomposite Ink for 2D Mutually Embedded Structure Interdigital Microsupercapacitors

Abstract

Recently, a substantial advancement in flexible printed electronics such as a microsupercapacitor (MSC) has motivated researchers to exploit the printable multifunctional graphene inks. Of particular interest are conductive-additive-manufacturing, eco-benign, high-viscosity inks devoid of multistep sophisticated postprocessing. Because of the high nanofiller loading required, fabricating such highly concentrated inks with an efficient combination of active nanofillers and appropriate rheological properties still remains a significant challenge. In this context, we demonstrate highly concentrated nanocomposite aqueous inks consisting essentially of mutually embedded two-dimensional (2D) nanosheets (graphene/MnO2) for the scalable screen printing of interdigital MSCs. Remarkably, the engineered Gr/MnO2-interpenetrated 2D nanostructure endows the flexible MSCs with an outstanding electrical conductivity (53.3 S/cm) and prominent energy storage performance. The as-printed patterns are presented on diversiform substrates with fine spatial uniformity, showcasing excellent flexibility and scalability. Importantly, the optimized Gr/MnO2-MSCs with a printed electrode thickness of 18.4 μm deliver a maximum single-cell areal capacitance of 16.1 mF cm–2 and a high energy density of 3.22 μW h cm–2 at a power density of 0.018 mW cm–2. The feasible protocol of formulating printable nanocomposite ink highlights the great potential of engineering multipurpose inks involving flake-like nanofillers for high-throughput and sustainable production of low-cost flexible and portable electronics.

Vertically Layered Multi‐Pair Interdigital Electrodes within a Single Sheet of Paper for High Energy Density

“…At the same current density of 0.1 mA cm −2 , P a and E a of the single SC were 0.16 and 27.87 μWh cm −2 . The single SC with the interdigital MnO 2 −Au‐paper electrode exhibited a higher energy density than previous reports of interdigital SCs [36,42–51] . For the parallel SC at the same current density of 0.1 mA cm −2 , the areal energy density was 86.58 μWh cm −2 at the same P a of 0.16 mW cm −2 .…”

“…The single SC with the interdigital MnO 2 À Au-paper electrode exhibited a higher energy density than previous reports of interdigital SCs. [36,[42][43][44][45][46][47][48][49][50][51] For the parallel SC at the same current density of 0.1 mA cm À 2 , the areal energy density was 86.58 μWh cm À 2 at the same P a of 0.16 mW cm À 2 . The parallel SC had an E a three orders of magnitude higher than the single SC.…”