Density Functional Theory Studies on Li Metal Electrode/Garnet‐Type Li₇La₃Zr₂O₁₂ Solid Electrolyte Interfaces for Application in All‐Solid‐State Batteries

Abstract

Garnet‐type Li7La3Zr2O12 (LLZ) and its analogs are considered potential candidates as solid electrolytes for all‐solid‐state Li metal batteries because their fast Li‐ion conductivity and chemical stability against Li metal anodes result in both safe and large energy densities. To date, several computational and experimental studies have been performed to obtain a more detailed understanding of the nonreactivity of garnet‐type LLZ with Li metal and related phenomena. Herein, first‐principles calculations based on the density functional theory approach are performed for Li metal/LLZ interfaces to elucidate the electronic and atomistic level aspects. It is confirmed that the valence band maximum and the conduction band minimum for the LLZ phase do not cross the Fermi level corresponding to the Li 2s band. In addition, it is found that the defect formation energies associated with both Li vacancy formation and interstitial Li formation are largely reduced. In particular, the formation energy associated with interstitial Li sites, i.e., Li+ insertion into the LLZ phase, is negative, indicating that spontaneous Li insertion is likely to proceed in the vicinity of the Li/LLZ interface. This new suggestion may help further elucidation of the reported interfacial behavior.

Na superionic conductor-type LiZr2(PO4)3 as a promising solid electrolyte for use in all-solid-state Li metal batteries

“…71 In our previous research, a total of 32 GB structure models were generated using an in-house software. 73,74 Specifically, two sliced bulk structures with various terminations were joined, such that the formation of the nearest neighbour cation-cation or anion-anion interactions was avoided by shifting one of the sliced bulk structures uniformly along the interfacial plane. Fig.…”

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

“…The increasing popularity of electric vehicles is expected to contribute to global environmental and energy issues; thus, the development of rechargeable batteries to power these vehicles is underway. , Currently, portable lithium-ion batteries are an attractive choice because of their high energy density, but the flammability of organic electrolytes poses a safety concern. , Accordingly, the research and development of all-solid-state batteries in which the organic electrolyte is replaced by an inorganic solid electrolyte is being pursued with increasing enthusiasm. , Among these, the garnet-type Li-ion conductive oxide material Li 7 La 3 Zr 2 O 12 (LLZ), first reported in 2007, has attracted attention because of its high ion conductivity (10 –3 S/cm at 298 K) and stability against metallic lithium. ,− Furthermore, doping of the Ta 5+ cations into Zr 4+ , i.e. Li 7– x La 3 Zr 2– x Ta x O 12 (LLZT), improves its Li + ionic conductivity by stabilizing the highly conductive cubic phase and maintains stability against Li metal. − In general, oxide solid electrolytes, including garnet-type materials, show high chemical stability in air, whereas sulfide solid electrolytes are prone to react with H 2 O and generate H 2 S gas. − However, it has become clear that solid garnet-type oxide electrolytes react with water and carbon dioxide in the air, leading to the deterioration of electrochemical performance, such as ionic conductivity of lithium.…”