Effect of specific surface area on capacitance in asymmetric carbon/α-MnO2 supercapacitors

✍ Scribed by Alexander J. Roberts; Robert C.T. Slade

• Publisher: Elsevier Science
• Year: 2010
• Tongue: English
• Weight: 957 KB
• Volume: 55
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/j.electacta.2010.01.004

✦ Synopsis

␣-MnO 2 has been made using a solid state synthesis and the specific surface area then modified through milling. The formation of ␣-MnO 2 (specific surface area 96 m 2 g -1 ) has been studied by SEM and powder XRD prior to milling. Electrode films (cast using MnO 2 , graphite and PVDF) have been investigated using N 2 sorption at 77 K and show a more complex relationship than their parent oxides. Specific capacitances of 235 F g -1 were observed in cyclic voltammetry studies in (NH 4 ) 2 SO 4 (aq.) electrolyte. Good cyclability was observed in hybrid C/MnO 2 cells investigated through both galvanostatic and electrochemical impedance techniques. The specific capacitances of the cells were found to correlate with S BET of the electrode films and not that of the parent MnO 2 powders.