Gravure-printed interdigital microsupercapacitors on a flexible polyimide substrate using crumpled graphene ink

In this paper, we demonstrate gravure printing of crumpled graphene ink to obtain a highly porous pattern of interdigitated electrodes, leading to an interdigital microsupercapacitor (MSC) on a flexible polyimide substrate. During the process of synthesizing crumpled graphene ink, Mg(OH)2 nanosheets as nanospacers were inserted into graphite oxide layers, resulting in sufficient crumples in graphene nanosheets to prevent the graphene sheets from restacking to enhance the ion transport and expose the electrochemical active area with oxygen-containing groups to provide more pseudo-capacitance. The gravure-printed interdigital MSCs achieved a high energy density (1.41 mW h cm(-3) at 25 mW cm(-3)) and high power density (0.35 mW h cm(-3) at 300 mW cm(-3)), respectively. Additionally, a liquid crystal display was driven by the two serial and two parallel connected MSCs for 35 s after charging for 3 s.