Photopatternable hydroxide ion electrolyte for solid-state micro-supercapacitors

•Synthesis of photopatternable hydroxide-ion-conducting solid electrolyte•High-room-temperature conductivity with excellent thermal and mechanical properties•Solid-state micro-supercapacitor demonstrated by photopatterning the electrolyte•Fabrication approach provides basis for miniaturized energy storage systems The rapid development implementation smart Internet Things (IoT)-based technologies have allowed technological innovations in various fields. However, conventional tools available to power these networks electronics are severely limited due stringent size constraints. This work describes synthesis characterization hydroxide-conducting electrolytes that can achieve high-resolution patterns via lithographic approaches. unique capability this material is especially promising miniaturizing mobile devices wireless communication sensing nodes constitute IoT. electrolyte coupled state-of-the-art electrode design fabrication approaches ultimately enables demonstration compact begin meet demands micro- nano-IoT electronics. Electrochemical (EES) provide high micropower considered be essential developing micro/nano such as nanorobotics, environmental sensors, connected One research direction field has been develop on-chip EES whose length scales integrate those electronic devices. In described here, we first report a patterned using standard lithography. By combining negative photoresist polymerizable ionic liquid, obtain thermally dimensionally stable, 10 mS cm−1. Patterning directly on interdigitated vanadium nitride (VN) electrodes scalable producing high-resolution, solid-state VN micro-supercapacitors (MSC) both single multiple Advances electrochemical technology changed landscape portable industry electric vehicle market past decade same track enabling “Internet Things” (IoT).1Liu H. Zhang G. Zheng X. Chen F. Duan Emerging microsystem applications: from integration.Int. J. Extrem Manuf. 2020; 2: 042001Crossref Scopus (67) Google Scholar A robust, high-energy high-power system key future electronics, microelectromechanical (MEMS), electronics.2Fan Liu Hu W. Zhong C. Lu supplies internet everything.InfoMat. 2019; 1: 130-139Crossref (82) Scholar,3Jayakumar Lee K. W.S. Raha A. Kim Y. Raghunathan V. Powering things.in: Proceedings 2014 International Symposium Low Power Electronics Design - ISLPED ’14. 2014: 375-380Crossref (168) sources often become limitation achieving small form factor required because components scale down poorly size. 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Patternable, solution-processed Ionogels thin-film electrolytes.Joule. 344-358Abstract (45) paper, describe possesses high-room-temperature along stability integrity. represents one few reported date and, best our knowledge, exhibit hydroxide conduction. ability photopatterned, fully fabricated We demonstrate application integrating it electrodes, leading addition demonstrating individual devices, characterize tandem device architectures lead increased cell voltages total currents beyond what Our creating involves modifying commercial SU-8 photoresists transport without compromising functionality. previously general methodology photopatterned sub-100 μm resolution.6Choi challenge conduction hydrophobic nature photoresist. strategy preparing involved two steps. First, cationic 1-Allyl-3-methylimidazolium [AMIM][TFSI] was grafted onto matrix. followed anion exchange incorporate hydroxides (Figures 1A S1). resulting consists while phase charge-carrying ions redox process (Figure 1B).22Nishimura N. Ohno 15th anniversary polymerised liquids.Polymer. 55: 3289-3297Crossref (131) Ionic successfully photomask cylindrical features 100 diameter signifies paired any × μm2 characterized energy-dispersive X-ray spectroscopy (EDS). presence constituents (sulfur fluorine) structure confirms matrix encapsulates S1B). After hydroxides, trace amounts fluorine sulfur were detected S1C). lithography-assisted crosslinking between cations verified analyzing Fourier transform infrared (FTIR) spectra. disappearance vinyl group 1,648 (stretching vibration C=C) upon polymerization indicates groups participating photopolymerization S2A). grafting liquids confirmed evaluating solubility IL miscible solvent (i.e., acetone ethanol). general, given ionogel system, contained network readily soluble certain media.18Le evident spectra Figure S2B covalently bonded no longer soluble. Once cation confirmed, TFSI− anions exchanged OH− 1M (aq.). approximate concentration [AMIM][OH]/SU-8 calculated 1.8 M volume assumption substituted. assessed observing changes characteristic peaks 2A) ascribed (Table S2) (3,200–3,400 cm−1). also clear IR absorbance bands assigned imidazolium (752, 1,432, 1,464 still present after exchanged. validated mobility leads charge NiCo2O4. transition metal undergoing reactions following mechanisms26Umeshbabu Rajeshkhanna Rao G.R. Urchin sheaf-like NiCo 2 O 4 nanostructures: application.Int. Hydr. Energy. 39: 15627-15638Crossref (137) Scholar,27Ding Qi facile cost-effective mesoporous NiCo2O4 nanoparticles capacitive behavior capacitors.J. Solid State 16: 3621-3633Crossref Scholar:NiCo2O4 + H2O ↔ NiOOH 2CoOOH e−(Equation 1) CoOOH CoO2 2) experiment, film coated polymerized electrode. cyclic voltammogram (CV) curves compared S3). similarity potential, peak response, observed gravimetric capacities (89 versus 92 mAh g−1 mV s−1) samples tested patternable control occurs electrolyte. observation consistent over range sweep rates (1, 2, 5, s−1), suggesting facilitates but coherent electrode/electrolyte interface. These attributes among vital electrolytes. determined thermogravimetric analysis (TGA) shown 2B. view possible heating effects associated operation, potential concern. quite stable showed appreciable weight loss below 300°C TG profile. contrast, unmodified begins undergo decomposition 200°C S4A). other feature solid-like nominal change heat treatment S4B). noticeable increase attributed [AMIM]-based Overall, results 5% 320°C. evaluated nanoindentation measurements 2C).23Wu G.M. Lin S.J. Yang C.C. 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Physically cross-linked homopolymer gels electrolyte-gated transistors.ACS Interfaces. 8813-8818Crossref (58) interesting note salts compounds.39Ue Ida Mori organic onium 1994; 141: 2989-2996Crossref (303) 3B compares Bode plots time constants 8.0 s 12.6 signifying shorter charge/discharge may kinetically response. fact fabricate difference transient impressive. experiments carried out [AMIM][TFSI]/SU-8 served films, thus determined. as-prepared strong preferential crystalline orientation (111) S6A) faceted growth S6B S6C). intercolumnar porosity morphology penetrate throughout S6D, S6E, S7). top planar polymerized, uniform penetration EDS elemental mapping image S7), showing signals originating layer. cross-sectional scanning electron microscope (SEM) S6C μm. composition film, probed photoelectron (XPS) S6F), literature.32Choi Scholar,33Robert c