Self-doped polypyrrole with ionizable sodium sulfonate as a renewable cathode material for sodium ion batteries.

A Na-host cathode is developed by grafting the polypyrrole chains with ionizable sodium sulfonate. Due to the immobile p-doping of organic anions, the self-doped polymer can act as a Na-host for reversible Na insertion-extraction reaction, thus offering a low cost and renewable organic cathode for Na ion battery applications.