Effects of Nd and Al co-doping on the microstructure and lithium-ion transport in Li7La3Zr2O12 solid-state batteries

In this study, we synthesized co-doped Li_6.25Al_0.25La_3-yNd_yZr₂O₁₂ (LALNZO) solid-state electrolytes with varying Nd contents to investigate the influence Nd plays on phase evolution, microstructure, and lithium-ion conductivity. It was found that incorporating Nd ions into the lattice reduced bulk resistance by controlling Li⁺ concentration. However, X-ray diffraction analysis revealed that excessive Nd content led to the formation of Nd₂O₃, which negatively impacted ion transport and increased grain boundary resistance. It is noteworthy that the LALNZO (y = 0.2) ceramic exhibited outstanding performance, with 94% relative density, and ionic conductivity of 4.7 × 10⁻⁴ S/cm. The activation energy was 0.32 eV. Further, Li_6.25Al_0.25La_2.8Nd_0.2Zr₂O₁₂ was able to demonstrate a stable capacity of 103 mA.h. g⁻¹ after 50 cycles at a current density of 0.1C when used as an electrolyte in lithium-ion batteries. The findings of this study provide valuable insights for developing advanced solid-state electrolytes for lithium-ion batteries.