Exploration of dopants for enhancing the ionic conductivity of LiTa2PO8 by first-principles calculations

LiTa 2 PO 8 (LTPO) has recently attracted considerable attention as a promising oxide-based solid electrolyte for next-generation batteries. In this study, we systematically investigated twenty doped LTPO compositions using density functional theory and conducted ab initio molecular dynamics simulations for selected candidates—Ba-, La-, and Te-doped LTPO—predicted to exhibit enhanced ionic transport. Pristine LTPO shows a bulk ionic conductivity of 0.889 mS cm −1 , whereas La-LTPO and Te-LTPO exhibit substantially higher conductivities (4.42 and 5.04 mS cm −1 , respectively), accompanied by reduced activation energies. These improvements originate from enlarged unit cell volumes, increased Li–Li distance, and the cooperative activation of multiple diffusion channels. In contrast, Ba-doping introduces an additional a -axis migration pathway but suppresses intrinsic b/c -axis transport, resulting in a substantially lower ionic conductivity (0.028 mS cm −1 ). Overall, these findings elucidate how aliovalent doping can fundamentally reconfigure lithium-ion migration pathways, offering valuable insights for the rational optimization of oxide-based solid electrolytes. • Systematic DFT screening of 20 dopants for LiTa 2 PO 8 solid electrolytes. • La and Te doping markedly enhance Li-ion conductivity and lower activation energy. • Ba doping activates a-axis transport but suppresses intrinsic b/c-axis pathways. • AIMD reveals dopant-dependent restructuring of lithium migration networks. • Design rules proposed for optimizing oxide solid electrolytes via aliovalent doping.