Dense Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) Solid Electrolytes Synthesized by Taylor–Couette Reactor for All Solid-State Nickel-Rich Lithium-Metal Batteries

Lithium aluminum titanium phosphate (LATP) is a promising solid electrolyte due to its high ionic conductivity at room temperature, thermal and chemical stability, non-flammability, and compatibility with high-energy cathodes. However, LATP faces significant challenges in practical applications, including interfacial contact with electrodes, high grain boundary resistance, and dendrite formation. In this study, we develop a novel strategy to synthesize dense LATP using a Taylor–Couette Reactor (TCR) for the first time. This method allows producing dense LATP with high purity from highly mixing and homogenization of reactants. Compared to conventional LATP, dense LATP exhibits higher total ionic conductivity (1 × 10⁻⁴ S cm⁻¹), a wider stability window (4.5 V versus Li/Li⁺), and longer cycling stability during lithium plating and stripping. The relative density of dense LATP is higher than that of the conventional variant (96.2% versus 90.3%). Electrochemical performance testing with a lithium nickel cobalt aluminum oxide (NCA) cathode demonstrates higher capacities, particularly at high rates. The capacity retention of NCA at 0.5C over 100 cycles using dense LATP is 83%, significantly better than the 51% retention observed with conventional LATP. Ex situ XRD analysis after cycling test attributes this retention to the improved chemical stability of dense LATP being more stable than the conventional one. This study suggests that LATP is economically viable and more stable for all-solid-state batteries.