Charge and discharge characteristics of lithium-ion graphite electrodes in solid-state cells

Lithium ions have been electrochemically intercalated into graphite in solid-state cells operating with solid polymer electrolytes based on poly(ethylene oxide) (PEO) complexed with lithium perchlorate (LiClO4). The working composite electrode is composed of active-divided natural graphite associated with P(EO)8-LiClO4 acting as a binder and a Li+ ionic conductor. Intercalation and de-intercalation of Li+ were performed using galvanostatic or voltammetry techniques. The curves obtained in our solid-state cells were compared with those performed in liquid ethylene carbonate-LiClO4 electrolyte. It is shown that in solid-state cells, side reactions occur both in the reduction and in the oxidation processes which leads to some uncertainty in the determination of the maximum reversible capacity of the graphite material.