Effect of LiOH solution additives on ionic conductivity of Li 6.25 Al 0.25 La 3 Zr 2 O 12 electrolytes prepared by cold sintering

Li 7 La 3 Zr 2 O 12 gives rise to much attention in solid-state batteries due to the excellent ionic conductivity, stable contact with lithium metal, and wide electrochemical window. The Li 6.25 Al 0.25 La 3 Zr 2 O 12 electrolytes were prepared by using cold sintering and then annealed at different temperatures. The effects of liquid-phase medium and annealing temperatures on phase compositions, bulk densities, and ionic conductivities were investigated by XRD, SEM, and electrochemical impedance. With the increasing of annealing temperatures, the ionic conductivities of the samples increased firstly and then decreased as the binary Li 6.25 Al 0.25 La 3 Zr 2 O 12 phase and La 2 Zr 2 O 7 phase were formed. The ionic conductivity of 17.8 × 10 −3 mS/cm was obtained for the sample with LiOH solution additives, which were annealed at 1000 °C. It can be ascribed to the rearrangement of the grain particles with the help of LiOH liquid phase and the reduction in the free energy of particles. The cold sintering combined with the annealed process is an effective way to increase grain conductivity and promote the further study of solid-state electrolytes.