Efficient Lightweight Supercapacitor with Compression Stability
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This article reports the fabrication of an electrochemical supercapacitor (ES) with high gravimetric and areal capacitance, achieved at a high mass ratio of active material to current collector. The active material, polypyrrole, was in situ polymerized in an aerogel-based current collector composed of crosslinked cellulose nanocrystals (CNC) and multiwalled carbon nanotubes (MWCNT). Mechanical robustness, flexibility and low impedance of the current collectors were achieved by the chemical crosslinking of CNC aerogels and efficient dispersion of MWCNT through the use of bile acid as a dispersant. Furthermore, the advanced electrode design resulted in low contact resistance. A single electrode areal capacitance of 2.1 F cm-2 was obtained at an active mass loading of 17.8 mg cm-2 and an active material to current collector mass ratio of 0.57. Large area ES electrodes and devices showed flexibility, excellent compression stability at 80% compression, and electrochemical cyclic stability over 5000 cycles. Moreover, good retention of capacitive properties was achieved at high charge-discharge rates and during compression cycling. The results of this investigation pave the way for the fabrication of advanced lightweight ES, which can be used for energy storage in wearable electronic devices and other applications.