Polyvinylpyrrolidone as binder for castable supercapacitor electrodes with high electrochemical performance in organic electrolytes

Polyvinylpyrrolidone (PVP) is presented as a "greener" alternative to commonly used supercapacitor binders, namely polyvinylidenedifluoride (PVDF) or polytetrafluoroethylene (PTFE). The key advantages of using PVP are that it is non-toxic and soluble in ethanol and it can be used to spray coat or drain cast activated carbon (AC) electrodes directly on a current collector such as aluminum foil in contrast to PTFE that requires rolling or PVDF that requires toxic N-methylpyrrolidone (NMP). The electrodes with the best mechanical stability incorporated 3.5 mass% of 1.300.000 g mol(-1) PVP. Compared to FIFE or PVDF, the resulting pore volume was significantly higher and the specific surface area significantly larger when using PVP (normalized to the amount of AC). A good electrochemical performance was observed in organic electrolytes for AC PVP electrodes: 112 or 97 F g(-1) at 0.1 A g(-1) in 1 M TEA-BF4 in propylene carbonate or acetonitrile, respectively. The performance stability was comparable to PTFE-bound electrodes when adjusting the maximum cell voltage to 2.5 V while preserving the manufacturing features of PVDF AC films. (Electro)chemical stability is shown by electrochemical testing and infrared vibrational spectroscopy for propylene carbonate and acetonitrile. (C) 2014 Elsevier B.V. All rights reserved.