Clean Solid-Electrolyte/Electrode Interfaces Double the Capacity of Solid-State Lithium Batteries.

Solid-state lithium (Li) batteries using spinel-oxide electrode materials such as LiNiMnO are promising power supplies for mobile devices and electric vehicles. Here, we demonstrate stable battery cycling between the LiNiMnO and LiNiMnO phases with working voltages of approximately 2.9 and 4.7 V versus Li/Li in solid-state Li batteries with contamination-free clean LiPO/LiNiMnO interfaces. This clean interface has the effect of doubling the capacity of conventional battery cycling between the LiNiMnO and LiNiMnO phases. We also investigated the structural changes between the LiNiMnO and LiNiMnO phases during battery cycling. Furthermore, we found an inhomogeneous distribution of the LiNiMnO phase in the LiNiMnO electrode, induced by spontaneous Li migration after the formation of the LiPO/LiNiMnO interface. These results indicate that the formation of a contamination-free clean LiPO/LiNiMnO interface is key to increase the battery capacity.