Investigation of Thermal Compatibility of Various Cathode Materials with Li6.25Al0.25La3Zr2O12 Solid Electrolyte for All-Solid-State Rechargeable Lithium Batteries

Wednesday, 4 October 2017: 09:00
Maryland D (Gaylord National Resort and Convention Center)
H. Munakata, J. Wakasugi, and K. Kanamura (Tokyo Metropolitan University)
Aluminum-doped lithium lanthanum zirconate (Li6.25Al0.25La3Zr2O12, Al-LLZ) has a relatively high Li+-ion conductivity of ~10-4 S cm-1 at room temperature and a wide electrochemical window enabling to use both lithium-metal anode and high potential cathodes, so that it has been focused as a promising solid electrolyte for all-solid-state rechargeable lithium batteries with high energy density. Several kinds of fabrication methods, which usually include heat treatment processes, have been utilized to fabricate cathode on Al-LLZ. However, the effect of heat treatments on the formation of impurities at the interface between Al-LLZ and cathode has not been fully understood yet. In this study, we investigated the thermal compatibility of conventional cathode materials (LiCoO2, LiMn2O4 and LiFePO4) with Al-LLZ by X-ray diffraction (XRD) and charge-discharge tests. The XRD analysis showed that LiCoO2/Al-LLZ mixture is stable up to 800°C, but impurities are formed in LiMn2O4/Al-LLZ mixture and LiFePO4/Al-LLZ mixture at 600 °C and 400 °C, respectively. This result indicates that the limit of heat treatment temperature for the formation of electrode/Al-LLZ interface strongly depends on the kind of electrode materials.