Aliovalent Ti4+ doping-mediated lithium vacancy to lower migration barriers of Li3YCl6

Li 3 YCl 6 (LYC) still faces challenges such as insufficient ionic conductivity and unstable interfacial contact. In this work, the solid electrolyte Li 3-x Y 1-x Ti x Cl 6 (0 ≤ x < 1) is successfully synthesized via aliovalent substitution of Y 3+ by Ti 4+ . Such aliovalent doping generates additional lithium vacancies within the lattice structure, which furnish extra migration sites for Li + and consequently lower the lithium diffusion energy barrier. Therefore, the material delivers an ionic conductivity of 0.66 mS cm −1 at x = 0.2, which is over 3 times higher than that of LYC. Furthermore, the introduction of Ti 4+ enhances the thermal and air stability, while exerting no significant influence on the electrochemical stability window of LYC. Benefiting from the good ionic conductivity, the all-solid-state battery using NCM811/LYTC retains 82.1% of its capacity after 500 cycles, demonstrating remarkable cycling and rate performance. Overall, more lithium vacancies effectively optimize migration pathways and lower migration barriers. The findings provide a practical reference for designing solid electrolytes with balanced performance and high safety.