Charge/Discharge Reactions via LiPON/Multilayer-Graphene Interfaces without Li⁺Desolvation/Solvation Processes

Li+ desolvation process has been regarded as the rate-limiting process in Li+ insertion reaction with graphite anode in lithium-ion batteries. In contrast, Li+ desolvation process is absent in solid-state batteries. We fabricated thin-film all-solid-state cells by depositing lithium phosphorus oxynitride glass (LiPON) electrolyte onto a multilayer-graphene (MGr) film by RF magnetron sputtering and measured the charge/discharge performance of the cells. It was found that the charge transfer resistance at the LiPON/MGr interface was significantly small, although the LiPON/MGr interface was supposed to have inorganic solid electrolyte interphase resulting from the LiPON reduction decomposition. Consequently, the dominant factor for the overall overpotential was the ohmic loss for LiPON, and hence the capacity retention was still maintained at 60% even at nearly 900C when the LiPON film thickness was 4 μm.