Fluorine-free binders for carbon black based electrochemical supercapacitors

Industrially manufactured carbon blacks (CBs) provide highly dispersed carbon materials with a specific surface of up to 1700 m(2) g(-1). Precompaction at p > 10 MPa in the presence of 3-10 wt% PTFE (provided as a dispersion) is known to lead to stable electrodes for electrochemical supercapacitors. Specific capacitances for single electrodes (C(s),(1)) were measured by constant current cycling (CCC) at 34 mA cm(-2) to be up to 250 F g(-1). It is shown that substitution of PTFE by fluorine-free binders, such as aqueous dispersions of polystyrene, styrene/butadien-copolymer and ethylene/acrylic acid copolymer is possible. Optimum systems were with 3-10 wt% binders of butadiene/styrene copolymers. They allowed stable results within hundreds of cycles. No shedding of the CB particles was observed, and swelling of the electrode was minimum.