Polyaniline-Lignin Interpenetrating Network for Supercapacitive Energy Storage

Because of increasing interest in environmentally benign supercapacitors, earth-abundant biopolymers have found their way into value-added applications. Herein, a promising nanocomposite based on an interpenetrating network of polyaniline and sulfonated lignin (lignosulfonate, LS) is presented. On the basis of an appropriate regulation of the nucleation kinetics and growth behavior via applying a series of rationally designed potential pulse patterns, a uniform PANI-LS film is achieved. On the basis of the fast rate of H⁺ insertion–deinsertion kinetics, rather than the slow SO₄^2– doping–dedoping process, the PANI-LS nanocomposite delivers specific capacitance of 1200 F g^–1 at 1 A g^–1 surpassing the best conducting polymer-lignin supercapacitors known. A symmetric PANI-LS||PANI-LS device delivers a high specific energy of 21.2 W h kg^–1, an outstanding specific power of 26.0 kW kg^–1, along with superb flexibility and excellent cycling stability. Thus, combining charge storage attributes of polyaniline and lignosulfonate enables a waste-to-wealth approach to improve the supercapacitive performance of polyaniline.