Particle Morphology and Lithium Segregation to Surfaces of the Li₇La₃Zr₂O₁₂ Solid Electrolyte

Abstract

Solid electrolytes for solid-state Li-ion batteries are stimulating considerable interest for next-generation energy storage applications. The Li 7 La 3 Zr 2 O 12 garnet-type solid electrolyte has received appreciable attention as a result of its high ionic conductivity.However, several challenges for the successful application of solid-state devices based on Li 7 La 3 Zr 2 O 12 remain, such as dendrite formation and maintaining physical contact at interfaces over many Li intercalation/extraction cycles. Here, we apply first-principles density functional theory to provide insights into the Li 7 La 3 Zr 2 O 12 particle morphology under various physical and chemical conditions. Our findings indicate Li segregation at the surfaces, suggesting Li-rich grain boundaries at typical synthesis and sintering conditions. On the basis of our results, we propose practical strategies to curb Li segregation at the Li 7 La 3 Zr 2 O 12 interfaces. This approach can be extended to other Li-ion conductors for the design of practical energy storage devices.

The Ab Initio Calculations on the Areal Specific Resistance of Li‐Metal/Li7La3Zr2O12 Interphase

“…was nor- Table 3, only direct decomposition mechanism is thermodynamically allowed with the G/f.u. Although the chemical decomposition of Li 7 La 3 Zr 2 O 12 was previously confirmed into Li 6 Zr 2 O 7 +La 2 O 3 +Li 8 ZrO 6 , [34] as Li 8 ZrO 6 can decompose into 0.5Li 6 Zr 2 O 7 +2.5Li 2 O with the G/f.u. of −1.53 eV.…”

“…Here, among the total 22 configurations, for 8 configurations the Li atoms can spontaneously fulfill the surface vacancies (i.e., the energy barrier is 0 eV) and promote the LLZO surface to evolve into Li-rich interphase, which is confirmed experimentally. The Li segregation was observed theoretically [34] and experimentally. As shown in Table S1, Supporting Information, there are seven configurations in all where the inner Li could spontaneously relax to outer positions beneath the surface.…”

“…As shown in Table S1, Supporting Information, there are seven configurations in all where the inner Li could spontaneously relax to outer positions beneath the surface. [34] In this study of direct relaxation of Li/LLZO, for seven configurations, Li vacancy remains at the surface. The Li segregation was observed theoretically [34] and experimentally.…”

Implications of Oxygen–Sulfur Exchange on Structural, Electronic Properties, and Stability of Alkali‐Metal Hexatitanates

“…Furthermore, research into solid electrolytes for all‐solid‐state batteries has seen a rapid rise in recent years. Both oxide and sulfide compounds, such as Li 10 GeP 2 S 12 , Li 10 SnP 2 S 12 , Li 7 La 3 Zr 2 O 12 , Li 3 OCl, and Li 3x La 2/3− x TiO 3 have been investigated as solid‐state electrolytes . Li 2 TiS 3 and Li 3 NbS 4 have also been tested as positive electrodes in the search for the best superionic conductors for all‐solid‐state batteries …”

Recent Advancements Towards Closing the Gap between Electrocatalysis and Battery Science Communities: The Computational Lithium Electrode and Activity–Stability Volcano Plots

“…The discussion of the electrocatalytic CER over RuO 2 (110) in the previouss ection clearly indicates that the appliede lectrode potential affects the structural configuration of the RuO 2 (110) electrode in the potential range of the CER, according to the formationo ft he active RuO 2 (110)-O ot phase (cf. [84][85][86][87][88] The constrained ab initio thermodynamics approach, as discussed in Sections 2.1 and 2.2 referring to the research areaso fh eterogeneous catalysis and electrocatalysis, respectively,w as transferredf rom (electro-)catalysis to electrode materials in LIBs by Exner only recently. Consequently,i tc an be assumed that the appliede lectrode potential also has an on-negligible effect on the energetics of surfaces tructures in LIBs, whichi mplies that an ovel approachi sc alled for that allows the atomic surfaces tructure of LIB electrode materials to be elucidated as af unction of the appliede lectrode potential.…”