Abstract <p>The introduction of lithium-ion solid electrolytes significantly escalates the safety risks associated with liquid electrolytes. Among various solid electrolytes, aluminium-doped Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) has gained attention in research due to its impressive ionic conductivity and stability in air. However, the conventional high-temperature sintering technique presents challenges like lithium loss and the formation of secondary phases. As a result, producing high-quality LATP solid electrolytes is quite challenging. Analysis of the X-ray diffraction patterns revealed that the LATP samples synthesized in this study exhibited a rhombohedral structure, consistent with the <i>R</i>-3<i>c</i> space group, and a novel method of excess lithium compensation sintering was introduced. This method utilizes lithium compensation (LiNO₃) effectively to mitigate the effects of lithium volatility. Furthermore, it serves as a sintering additive to enhance the densification of LATP during the sintering process. In this study, the optimal sample for sintering at 1050°C was identified by assessing the microstructure and electrochemical characteristics of the electrolyte, alongside an investigation of lithium doping. The lithium-doped LATP solid electrolyte, containing 10 wt% lithium, demonstrated a conductivity of 8.7 × 10⁻³ S/cm and low activation energy of 0.278 eV. On survey, the obtained results are proven to be one among the best solid electrolytes for lithium ion batteries.</p>