Reaction Kinetics of Carbonation at the Surface of Garnet-Type Li₇La₃Zr₂O₁₂ as Solid Electrolytes for All-Solid-State Li Ion Batteries

Abstract

Garnet-type Li7La3Zr2O12 has attracted attention as a promising candidate for solid electrolytes in all-solid-state lithium ion metal batteries because it exhibits high Li ion conductivity and is inert in the presence of metallic Li. However, this material is known to react with water and carbon dioxide gas, even under ambient conditions, which can cause degradation, such as a decrease in ionic conductivity. In this study, the reaction rate of the carbonation processes under both humid and dry conditions was evaluated using thermal analysis. We confirmed that carbonation did not occur at <700 K under dry conditions. The reaction kinetics were found to initially be phase-boundary controlled and then diffusion controlled, and the corresponding activation energies were estimated to be 0.5 and 0.8 eV, respectively.

Thermal properties and lattice anharmonicity of Li-ion conducting garnet solid electrolyte Li6.5La3Zr1.5Ta0.5O12

“…It has been reported that the reaction usually occurred at the surface of the grain, and the garnet structure was preserved. 65 However, our result suggests that the reaction can also occur within grains, leading to grain fracture.…”

“…Some rough layers are formed on the surface of some grains, indicating that the grain surface of LLZTO reacted with moisture, as reported in previous studies. 65,66 Some grains show large cracks, which can be caused by the volume change due to the reaction with moisture. Additional SEM images of cracked grains can be found in Fig.…”

Li, Na, K, Mg, Zn, Al, and Ca Anode Interface Chemistries Developed by Solid‐State Electrolytes

“…Since 1969, [160] numerous garnets, including (Li RT. [161][162][163][164][165][166][66][67][68] 𝛽-Alumina SE (BASE) is the Na + ion conductor for Na-S high-temperature batteries. Similarly, K-incorporated BASE shows K + ion conductivity.…”

Effect of H+ Exchange and Surface Impurities on Bulk and Interfacial Electrochemistry of Garnet Solid Electrolytes

“…Among solid electrolyte (SE) chemistries, doped cubic Li 7 La 3 Zr 2 O 12 (LLZO) has garnered significant attention as a separator material due to its high bulk ionic conductivity and minimal chemical reactivity with Li metal. − Despite this apparent stability in contact with Li metal, LLZO suffers from other surface reactions under common processing conditions. It is well-known that LLZO undergoes Li + /H + exchange in the presence of protic solvents, such as water vapor in air. − Neutron diffraction and transmission electron microscopy studies have shown that protons insert into the Li + sites of LLZO without modifying the cubic crystal structure. In air, Li + /H + exchange results in the formation of surface contaminants, such as LiOH and Li 2 CO 3 , as summarized by the following equations: ,, Li 7 La 3 Zr 2 normalO 12 + x normalH 2 normalO → Li 7 − x normalH x La 3 Zr 2 normalO 12 + x LiOH 2 LiOH + CO 2 → Li 2 CO 3 + normalH 2 normalO Equation is also written in Kröger Vink notation as Li Li × + H 2 O → H Li × + LiOH.…”