In situ synchrotron wide-angle X-ray scattering study on rapid lithiation of graphite anode via direct contact method for Li-ion capacitors

Lithium pre-doping of graphite anode is a key process to achieve high energy density lithium-ion capacitor. In this study, in situ synchrotron wide-angle X-ray scattering examinations directly revealed that the direct contact (DC) method, simply achieved through direct physical contact between graphite electrode and sacrificial lithium metal in electrolyte, provides much faster phase transformation from stage 1 to stage 1 than conventional electronic charger (EC) and external short circuit (ESC) methods at the same doping time level. The observations indicate that DC method achieves faster pre-lithiation rate of graphite electrode than EC and ESC processes.