Low temperature synthesis of Al-doped Li7La3Zr2O12 solid electrolyte by a sol–gel process

Abstract

Al-doped Li7La3Zr2O12 (LLZ) was prepared by a sol-gel process using lithium nitrate, lanthanum nitrate hexahydrate, zirconium propoxide and aluminum tri sec-butoxide as starting materials. Single phase of cubic LLZ was obtained by a heat treatment at 700 o C, which is lower than that in the solid state reaction process. The LLZ powders were sintered at 900°C using LiBO2 or Li3BO3 to form composite solid electrolyte. In the composite sintered with LiBO2, La2Zr2O7 was formed as an impurity phase. On the other hand, in the composite sintered with Li3BO3, single phase of cubic LLZ was obtained. The composite of Al-doped LLZ and Li3BO3 sintered at 900°C showed the total electrical conductivity of 1.9×10-5 S cm-1 , while Al-doped LLZ pellet without additives showed 1.6×10-6 S cm-1 .

Preparation of Li7La3(Zr2−,Nb )O12 (x= 0–1.5) and Li3BO3/LiBO2 composites at low temperatures using a sol–gel process

“…More recently, additives of sintering as LiBO 2 , Li 3 BO 3 , Li 3 PO 4 , and Li 4 SiO 4 have shown positive effects for reducing the sintering temperature and maintaining high conductivity [14,[17][18][19]. Tadanaga and a coworker reported Li-ion conductivity of 1 × 10 −4 S cm −1 at 30°C using Li 3 BO 3 as an additive to pristine LLZO-Al, prepared at the lower sintering temperature of 900°C [14].…”

Effect of Excess Li on the Structural and Electrical Properties of Garnet-Type Li6La3Ta1.5Y0.5O12

“…11 Attempts have also been made to reduce the sintering temperature and improve the control of stoichiometry via wet chemical synthesis as well as through additives acting as sintering aids. [12][13][14][15][16][17][18] It has been shown that Al migrates from the alumina crucible used for garnet synthesis, causing significant effects in the material including stabilization of the cubic phase. [15][16][17][18] Lithium salts such as Li 2 20 They also found that the glassy-like phase formed at the grain-boundaries increases the density of material as well as helps to decrease the grain-boundary and improve the total Li + conductivity.…”

Fabrication of all-solid-state lithium secondary batteries with amorphous TiS4 positive electrodes and Li7La3Zr2O12 solid electrolytes

“…LLZ was prepared by a sol-gel process using LiNO 3 (Wako, Japan), La(NO 3 ) 3 ·6H 2 O (Wako, Japan), Zr(O-n-C 3 H 7 ) 4 (Sigma-Aldrich), Al(Osec-C 4 H 9 ) 3 , as starting materials [14,15]. CH 3 COCH 2 COOC 2 H 5 (EAcAc) was used as a stabilizing agent for the alkoxides.…”

“…Recently, we have reported that LLZ was prepared at a lower temperature of 900°C by the sol-gel method [14,15]. High lithium ion conductive composite electrolyte with LLZ and amorphous Li 3 BO 3 was prepared from sol-gel derived precursor powders of LLZ and Li 3 BO 3 .…”