Reducing the environmental footprint of solid-electrolytes - a green synthesis route for LATP

Abstract

Lithium aluminium titanium phosphate Li_1.5Al_0.5Ti_1.5(PO₄)₃ (LATP) is a promising and intensively studied solid electrolyte for the development of ceramic solid-state batteries. LATP has competitive Li-ion conductivity at room temperature, very high oxidation stability, is non-flammable, cheap and environmentally friendly. LATP can be produced in large quantities by a solution-assisted solid-state process, which can be easily scaled up for industrial applications. We show that LATP synthesis can be further simplified, reducing synthesis time, lowering energy consumption, and most importantly, reducing the environmental footprint. The core of this approach is the use of AlPO₄ as Al source instead of aluminium acetate. This reduces the use of H₃PO₄ in the reaction and reduces the amount of organic components, resulting in a CO₂-free synthesis. In addition, our approach allows for direct sintering without the need for high-energy calcination steps, reducing CO₂ emissions by 48% during processing. The resulting LATP exhibits very high phase purity and a homogenous microstructure, resulting in a total ionic conductivity of 0.62 mS·cm⁻¹ at room temperature with an activation energy of 0.33 eV.