Electrochemical Insertion of Lithium into Polyacrylonitrile‐Based Disordered Carbons

Electrochemical lithium insertion into polyacrylonitrile (PAN)‐based disordered carbons was studied using the techniques of discharge/charge tests, cyclic voltammetry, and 7 Li nuclear magnetic resonance (NMR) spectroscopy. The PAN‐based carbons were prepared by vacuum pyrolysis of PAN at 500, 800, and 1000°C. They showed charge capacities between 254 and 380 mAh/g in the first cycle. 7 Li NMR spectra showed two kinds of lithium insertion sites in the PAN‐based carbons: a reversible site where lithium is removed in the subsequent charge process and an irreversible site where lithium remains intact. The NMR results suggest that lithium in fully Li‐inserted PAN‐based carbons has an ionic character, and reversible site lithium resides between negatively charged carbon layers.