LiF-Assisted Synthesis of Perovskite-Type Li0.35La0.55TiO3 Solid Electrolyte for Rechargeable Lithium-Metal Batteries

Perovskite-type solid-state Li 0.35 La 0.55 TiO 3 - x wt.% LiF (LLTO-F x , x = 0, 2, 4 and 6) electrolytes have been successfully synthesized through a solid-state reaction method. The effects of amount of LiF addition on the crystal structure, morphology, and ionic conductivity of LLTO were investigated. All the samples formed perovskite structure, and the grain size increased gradually with increasing LiF content. Moreover, because it had the highest relative density (95.4%), the LLTO-F2 electrolyte exhibited the highest total conductivity of 1.02 × 10 −4 S/cm with relatively low activation energy of 0.26 eV, being suitable for use in solid-state batteries. The Li/LLTO-F2/V 2 O 5 cell exhibited a specific capacity of about 180 mAh/g in the first few cycles and maintained 150 mAh/g after 55 cycles, demonstrating good cycling properties. Moreover, cells assembled with different cathodes, such as LiFePO 4 and LiCoO 2 , also displayed excellent electrochemical performance. These results suggest that the sintering additive LiF is very effective for ultimately achieving safe hybrid solid-state lithium battery systems. Graphic Abstract