Planar ultracapacitors of miniature interdigital electrode loaded with hydrous RuO2 and RuO2 nanorods

Wafer-level fabrication process for fully encapsulated micro-supercapacitors with high specific energy

“…Various technologies were considered for miniaturization and integration of supercapacitors on planar substrates going from ''printed electronics'' (Kaempgen et al 2009;Pushparaj et al 2007;Hu et al 2010) to microfabrication technologies involving either sputtering or electrodeposition of metal oxides (Yoon et al 2001;Kim et al 2003;Liu et al 2010), synthesis of conductive polymers (Sung et al 2003(Sung et al , 2006Sun and Chen 2009) or printing of activated carbon Jiang et al 2009;Pech et al 2010a, b). As it will be detailed hereafter, the main difficulty lies in the integration of the active material and the electrolyte (liquid, gel or solid) within a microfabrication process, while reaching highest possible specific energy.…”

Selective deposition of nanostructured ruthenium oxide using Tobacco mosaic virus for micro-supercapacitors in solid Nafion electrolyte

“…Due to the inherent challenges of microfabrication process integration, there are far fewer reported breakthroughs with RuO 2 micro-supercapacitors than with RuO 2 electrodes prepared by bulk synthesis methods. A mix of RuO 2 nanorods and RuO 2 $xH 2 O on interdigitated electrodes produced supercapacitors with 12e41 mF cm À1 in aqueous 0.5M H 2 SO 4 electrolyte [16], and electrodeposition of hydrous RuO 2 onto gold microelectrodes was reported at 0.2 mF cm À1 in aqueous 0.5M H 2 SO 4 electrolyte [17]. Recently, electrodeposition of hydrous RuO 2 on a high-aspect-ratio silicon microtemplate produced electrodes with 92 mF cm À2 (or 23 mF cm À2 based on device footprint) in neutral aqueous 0.1M Na 2 SO 4 electrolyte [18], and this value was increased to 148 mF cm À2 (or 37 mF cm À2 based on device footprint) by introducing CNT into the deposition process [19].…”

Photoresist-derived porous carbon for on-chip micro-supercapacitors

“…However, for powering microsensors or other microdevices, a scalable technique for deposition and patterning of this highly porous carbon material must be developed to enable on-chip integrated micro-supercapacitors. Some proposed carbon-based electrode materials for micro-supercapacitors include ink-jet printed activated carbon, CNTs, graphene, and carbide-derived carbon [4][5][6][7][8][9]. While these techniques hold promise, each approach presents significant fabrication challenges: ink-jet printing requires complex synthesis and binder materials and may be difficult to scale, carbon nanotubes are difficult to grow controllably and have high contact resistances with most substrates, graphene requires high temperatures or transfer processes to fabricate, and carbide-derived carbon involves a lengthy fabrication with multiple deposition and patterning steps.…”