Phase Evolution and Li Diffusion in LATP Solid‐State Electrolyte Synthesized via a Direct Heat‐Cycling Method

Abstract

Herein, the direct synthesis of phase‐pure lithium aluminum titanium phosphate (Li1.3Al0.3Ti1.7(PO4)3, LATP) solid‐electrolyte powder in 220 min and relatively low temperatures (850 °C) is achieved via a new (cyclic) fast heat treatment (c‐FHT) route. The complex structural evolution highlights rate‐limited lithium incorporation of intermediate metal phosphates formed prior to the final phase‐pure LATP. The prepared LATP product powder displays similar bulk (2 × 10−10 cm2 s−1) and local (3 × 10−10 cm2 s−1) values for lithium diffusion coefficients (DLi) characterized by electrochemical impedance spectroscopy and muon spin relaxation (μSR), respectively. The similarity between both DLi values suggests excellent retention of inter‐ and intraparticle lithium diffusion, which is attributed to the absence of deleterious surface impurities such as AlPO4. A low‐energy barrier (Ea = 73 meV) of lithium diffusion is also estimated from the μSR data.

Nanoscale Synthesis of Li1.3Al0.3Ti1.7(PO4)3 Solid-State Lithium Ion Battery Electrolyte: A Structural and Ionic Conductivity Study

“…The stretching vibrational modes of P–O appeared in the range of 900–1130 cm –1 . The three small deconvoluted peaks in the region of (1028, 1032, 1044 cm –1 ) are attributed to the substitution of Al 3+ or Li + with Ti 4+ …”

“…The three small deconvoluted peaks in the region of (1028, 1032, 1044 cm −1 ) are attributed to the substitution of Al 3+ or Li + with Ti 4+ . 47 As shown in Figure 2A, the field emission scanning electron microscopy (FE-SEM) image of C-LATP-800−2 before ball milling shows an irregular morphology with a larger grain size, which affects the uniform sintering process. Figure 2B−D portrays the FE-SEM and TEM images of C-LATP-800−2 after the ball milling.…”