Investigation into Lithium-Ion Conductivity and Redox Stability of Selenium-Doped Lithium Lanthanum Titanate

Abstract

Selenium-doped lithium lanthanum titanate of composition Li₀.₃₃La₀.₅₆Ti₁₋ₓSeₓO3 (x = 0, 0.025, 0.050, 0.075) was attempted using a two-step conventional synthesis process to investigate the potential of the material as a solid-state electrolyte in lithium-ion batteries. Impedance spectroscopy data yielded a maximum room temperature bulk conductivity of (1.73 ± 0.10) x 10⁻³ S cm⁻¹ (EBulk = 0.35 ± 0.03 eV) and grain boundary conductivity of (1.20 ± 0.10) x 10⁻⁴ S cm⁻¹ (EGB = 0.37 ± 0.01 eV) for nominal composition x = 0.050. Preliminary stability measurements through three-electrode cyclic voltammetry suggests potential for LLTO stabilization against Li metal anode through further selenium substitution. However, further work is required to confirm the exact elemental composition of selenium-doped samples.