Synthesis and Conductive Properties of Li1+xAlxTi2-x(PO4)3 (x = 0, 0.3, 0.5) by Sol-Gel Method

Abstract

Li 1+x Al x Ti 2-x (PO 4 ) 3 (LATP) is a promising solid electrolyte for all-solid-state Li ion batteries. In this study, LATP is prepared through a sol-gel method using relatively the inexpensive reagents TiCl 4 . The thermal behavior, structural characteristics, fractured surface morphology, ion conductivity, and activation energy of the LATP sintered bodies are investigated by TG-DTA, X-ray diffraction, FE-SEM, and by an impedance method. A gelation powder was calcined at 500 Key words Li 1+x Al x Ti 2-x (PO 4 ) 3 , sol-gel, ion conductivity, solid electrolyte, activation energy. 서 론

Sulfide and Oxide Inorganic Solid Electrolytes for All-Solid-State Li Batteries: A Review

“…Cationic carriers move from one site to another through bottlenecks, and the size of the bottlenecks depends on the nature of the skeleton ions and carrier concentrations. Many efforts have been invested to chemically substitute the Na and Zr sites of NASICON and obtain a variety of isostructural Li compounds, such as Li(M2 4+ )(PO4)3, (M = Ti, Zr, Hf, Ge, Sn) [360][361][362][363], LiM V M III (PO4)3 (M V = Nb, Ta; M III = Al, Cr, Fe) [364], Li1−xM2-−xM′xP3O12 (M = Hf, Zr; M′ = Ti, Nb) [353], and Li1+x(M2−x 4+ ,Nx 3+ )(PO4)3 (M = Ti, Zr, Hf, Ge, Sn; N = Al, Ga, In) [362]. Among the aforementioned electrolytes, hexagonal-type structures LATP and Li1.5Al0.5Ge1.5P3O12 (LAGP) ( Figure 29) have been well studied owing to their high ionic conductivities.…”

“…(ii) Many researchers have attempted to improve the Li + ion conductivity of LATP electrolytes using different synthesis methods, such as the solid-state, sol-gel [363], melt quenching, co-precipitation [369], microwave-assisted reactive sintering, SPS [370], spray drying, spin coating [371], tape casting [372], and RF magnetron sputtering [373] methods, and different reaction conditions, such as different synthesis temperatures in the range of 700-1100 • C. Among all preparation methods, the sol-gel and solution-based ones generated LATP electrolytes with improved conductivity (Figure 30a-d). The crystallization of LATP starts at approximately 700 • C and its phase formation occurs in the range of 750-850 • C; in addition, decomposition (or phase segregation) occurs at 850 • C and leads to the formation of AlPO 4 , TiO 2 , and Li 4 P 2 O 7 phases [374].…”