Yaoyu Ren,Hui Deng,Rujun Chen,Yang Shen,Yuanhua Lin,Ce-Wen Nan
Cubic garnet-type Al-contained Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 (Al-LLZTO) ceramics were prepared by conventional solid-state reaction using either Li 2 CO 3 or LiOH·H 2 O as Li source. The effects of Li source on the lithium ionic conductivity of Al-LLZTO ceramics were systematically investigated by comparing the synthesis processes and characteristics of the mother powders and the microstructures of the sintered pellets made with different Li sources. Different calcination processes of the raw materials mixtures with different Li sources are revealed by thermogravimetry-differential scanning calorimetry investigation. The mother powder derived from LiOH·H 2 O is of higher sintering activity than those made from Li 2 CO 3 at the same calcination temperature. For the LiOH·H 2 O-derived pellets, higher relative density and enhanced lithium-ion conductivity is achieved at a much lower sintering temperature of 1100 °C as compared with Li 2 CO 3 -derived pellets. The highest conductivity obtained at room temperature is 9.28 × 10 −4 S cm −1 , which is the highest value reported to date for the same Ta doping level.
Li Huang,Jian Gao,Zhijie Bi,Ning Zhao,Jipeng Wu,Qiu Fang,Xuefeng Wang,Yong Wan,Xiangxin Guo
The cubic garnet Li7La3Zr2O12(c-LLZO) is one of the most promising solid electrolytes due to its high ionic conductivity and large electrochemical window. However, the critical issue of Li2CO3formation on the c-LLZO surface when exposed to air is problematic, which is detrimental to the ionic conductivity and storage. Herein, comparative studies were carried out on the air stability of Al-doped Li7La3Zr2O12(Al-LLZO), Al-Ta-doped Li7La3Zr2O12(Al-LLZTO), and Al-Nb-doped Li7La3Zr2O12(Al-LLZNO). It was found that Al-LLZTO and Al-LLZNO are less reactive with air than Al-LLZO. The morphology of Li2CO3on Al-LLZTO micro-sized powders after air exposure was island-like with ~1.5 μm in thickness. The interfacial resistance of Li/Al-LLZTO was also a factor of ~3 smaller than that of Li/Al-LLZO, leading to the improved cycle stability of Li/Al-LLZTO/Li symmetric cells. The first-principles calculations based on density functional theory (DFT) verified that the decomposition energy of Al-LLZTO was larger than that of Al-LLZO, inhibiting the reaction product of Li2O and, thus, the next step product of Li2CO3following the reactions of Li2O + H2O → LiOH and LiOH + CO2→ Li2CO3.
危险品化学品经营许可证（带存储）