Direct electrochemical N-doping to carbon paper in molten LiCl-KCl-Li3N

Graphite materials are widely used as electrode materials for electrochemical energy storage. N-doping is an effective method for enhancing the electrochemical properties of graphite. A novel one-step N-doping method for complete and compact carbon paper was proposed for molten salt electrolysis in the LiCl-KCl-Li3N system. The results show that the degree of graphitization of carbon paper can be improved by the electrolysis of molten salts, especially at 2.0 V. Nitrogen gas was produced at the anode and nitrogen atoms can substitute carbon atoms of carbon paper at different sites to create nitrogen doping during the electrolysis process. The doping content of N in carbon paper is up to 13.0wt%. There were three groups of nitrogen atoms, i.e. quaternary N (N-Q), pyrrolic N (N-5), and pyridinic N (N-6) in N-doping carbon paper. N-doping carbon paper as an Al-ion battery cathode shows strong charge-recharge properties.