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Reaction mechanisms of lithium garnet pellets in ambient air: The effect of humidity and CO 2
Author(s) -
Xia Wenhao,
Xu Biyi,
Duan Huanan,
Tang Xiaoyi,
Guo Yiping,
Kang Hongmei,
Li Hua,
Liu Hezhou
Publication year - 2017
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.14865
Subject(s) - pellets , humidity , ionic conductivity , relative humidity , chemistry , conductivity , moisture , ionic bonding , pellet , drop (telecommunication) , materials science , mineralogy , composite material , ion , organic chemistry , electrode , meteorology , electrolyte , physics , telecommunications , computer science
Li 7 La 3 Zr 2 O 12 ( LLZO ) has been reported to react in humid air to form Li 2 CO 3 on the surface, which decreases ionic conductivity. To study the reaction mechanism, 0.5‐mol Ta‐doped LLZO (0.5Ta– LLZO ) pellets are exposed in dry (humidity ~5%) and humid air (humidity ~80%) for 6 weeks, respectively. After exposure in humid air, the formation of Li 2 CO 3 on the pellet surface is confirmed experimentally and the room‐temperature ionic conductivity is found to drop from 6.45×10 −4 S cm −1 to 3.61×10 −4 S cm −1 . Whereas for the 0.5Ta– LLZO samples exposed in dry air, the amount of formed Li 2 CO 3 is much less and the ionic conductivity barely decreases. To further clarify the reaction mechanism of 0.5Ta– LLZO pellets with moisture, we decouple the reactions between 0.5Ta– LLZO with water and CO 2 by immersing 0.5Ta– LLZO pellets in deionized water for 1 week and then exposing them to ambient air for another week. After immersion in deionized water, Li + /H + exchange occurs and Li OH H 2 O forms on the surface, which is a necessary intermediate step for the Li 2 CO 3 formation. Based on these observations, a reaction model is proposed and discussed.