On-chip and free-standing elastic carbon films for micro-supercapacitors

On-chip and free-standing elastic carbon films for micro-supercapacitors ; P. Haung et al., Science 2016
Radio frequency identification (RFID) tags for the development of smart environments, more commonly termed “internet of things”, cell phones or laptops are examples of electronic devices that need high performance miniaturized electrochemical storage devices able to deliver energy from their environment.
Integration of electrochemical capacitors with silicon-based electronics is a major challenge limiting energy storage on a chip. A couple of years ago, we proposed a way to prepare micro-supercapacitors from the chlorination of TiC ceramics (Science 2010) but it was not possible to make integrated micro supercapacitor cells on Si wafer from this approach.
In this paper, we describe a wafer-scale process for manufacturing strongly adhering carbide-derived carbon films and interdigital micro-supercapacitors with embedded TiC current collectors, which is fully compatible with current microfabrication and silicon-based device technology. The process produces carbon elastomer with a unique combination of microporosity, electrochemical and mechanical properties. When TiC films were partially chlorinated and transformed into porous carbons (see figures below), Si / TiC / porous carbon electrodes could be prepared with high adherence properties.
Capacitance of these films (410 F.cm-3 / 200 mF.cm-² in aqueous electrolyte and 170 F.cm-3 / 85 mF.cm-² in organic electrolyte) can challenge the best carbon supercapacitors reported so far.

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_We also demonstrated preparation of self-supported, stand-alone and mechanically stable micrometer-thick porous carbon films (see figure below) of 0.6 nm pore size with Young’s modulus of 14.5 GPa, dry friction coefficient below 0.2, with possibility of further transfer onto flexible substrates.

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