Ultrathin Paper Microsupercapacitors for Electronic Skin Applications

Ultrathin devices are rapidly developing for skin-compatible medical applications and wearable electronics. Powering skin-interfaced electronics requires thin and lightweight energy storage devices, where solution-processing enables scalable fabrication. To attain such devices, a sequential deposition is employed to achieve all spray-coated symmetric microsupercapacitors (mu SCs) on ultrathin parylene C substrates, where both electrode and gel electrolyte are based on the cheap and abundant biopolymer, cellulose. The optimized spraying procedure allows an overall device thickness of approximate to 11 mu m to be obtained with a 40% active material volume fraction and a resulting volumetric capacitance of 7 F cm(-3). Long-term operation capability (90% of capacitance retention after 10(4) cycles) and mechanical robustness are achieved (1000 cycles, capacitance retention of 98%) under extreme bending (rolling) conditions. Finite element analysis is utilized to simulate stresses and strains in real-sized mu SCs under different bending conditions. Moreover, an organic electrochromic display is printed and powered with two serially connected mu-SCs as an example of a wearable, skin-integrated, fully organic electronic application.Funding Agencies|European Research Council (ERC) under the European Unions Horizon 2020 research and innovation programEuropean Research Council (ERC) [949191]; city council of Brno, Czech Republic