Foaming suppression during the solid-state synthesis of the Li1.3Al0.3Ti1.7(PO4)3 solid electrolyte

Abstract

In this work, the effect of carbon on the suppression of foaming during the solid-state synthesis of the Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) solid electrolyte was studied. According to thermal analysis data, mechanically activated mixtures with and without carbon exhibit similar behavior. The presence of carbon does not affect the gas release process during decomposition, and foaming suppression occurs due to the change in viscosity of the melt created by NH₄H₂PO₄. Slow LATP-S, medium LATP-M and fast LATP-F synthesis routes were used to evaluate the optimal conditions for LATP preparation. It was found that the use of carbon to suppress foaming eliminated the need for preheating and milling and reduced the synthesis time to 2.5 h (LATP-F). The effect of the synthesis route on the phase composition, morphology, conductive and electrochemical properties of LATP-S, LATP-M and LATP-F was investigated. No significant differences in studied properties were found for the synthesizer LATP samples excluding particle size distribution. Comparison of the granulometric curves showed that the fast synthesis method resulted in a decrease in particle size. The values of the ionic conductivity σ_ion for LATP-S, LATP-M and LATP-F are equal to ∼10⁻⁴ S cm⁻¹, while the electronic conductivity σ_e does not exeed∙10⁻⁹ S cm⁻¹. The study of the electrochemical stability window of the synthesized LATP samples was showed that these solid electrolytes are stable up to 4.65–4.70 V.