Recent advances in Li1+xAlxTi2−x(PO4)3 solid-state electrolyte for safe lithium batteries

Lithium batteries have been indispensable for powering consumer electronics and electric vehicles. However, the utilization of highly flammable/reactive/volatile liquid electrolytes not only poses safety concerns of battery combustion and explosion, but also triggers severe side reactions with electrodes. Solid-state electrolytes with a high ionic conductivity, a low lithium-ion diffusion impedance, a good chemical compatibility, and a superior electrochemical stability have been regarded as critical components to develop safe and high-energy lithium batteries. Specifically, NASICON (Sodium Super Ionic Conductor)-type lithium titanium aluminum phosphate (LATP) in the composition of Li1+xAlxTi2-X(PO4)3 has emerged as a promising solid-state electrolyte (SSE) because of its high ionic conductivity and low manufacturing cost. Herein, the recent progress on the development of LATP SSE is systematically reviewed. The fundamental structure and ion conduction mechanism are introduced and the synthetic routes for LATP SSE are summarized. In addition, we discuss the key parameters of ionic conductivity and exemplify the typical applications of LATP in various electrochemical systems. Despite the technical efforts required for commercializing LATP in practical batteries, this review, focusing on the microstructure, grain boundary resistance, and interfacial behaviors, would pave the way to a bright future for all-solid-state lithium batteries with an exceptional safety, a superior energy density, an outstanding cycle durability, and an acceptable manufacturing cost.