Li7La3Zr2O12 Solid Electrolyte Research Articles

Microstructure equilibration with consideration of elastic and interfacial interactions via quantum annealing with application to the solid electrolyte LLZO

We present a detailed derivation of the elastic energy of a homogeneous, isotropic linear elastic medium consisting of different coherent martensite variants or phases and its mapping to an Ising model, as required for an efficient quantum annealing determination of the equilibrium microstructure. The approach is demonstrated for a sample with a large number of grains with a tetragonal eigenstrain. Furthermore, we illustrate how the elastic effects may lead to the formation of ion conducting channels in the doped solid electrolyte Li7La3Zr2O12 (LLZO). Apart from bulk elastic and chemical effect we demonstrate how to include interfacial effects into the quantum annealing approach and emphasize the importance of high precision elastic calculations. Published by the American Physical Society 2024

Reasonable design a high-entropy garnet-type solid electrolyte for all-solid-state lithium batteries

Traditional garnet solid electrolyte (Li7La3Zr2O12) suffers from low room temperature ionic conductivity, poor air stability, high sintering temperature and energy consumption. Considering the development prospects of high-entropy materials with high structural disorder and strong component controllability in the field of electrochemical energy storage, herein, a novel high-entropy garnet-type oxide solid electrolyte, Li5.75Ga0.25La3Zr0.5Ti0.5Sn0.5Nb0.5O12 (LGLZTSNO) was constructed by partially replacing the Li and Zr sites in Li7La3Zr2O12 with Ga and Ti/Sn/Nb elements, respectively. The experimental and density functional theory (DFT) calculation results show that the high-entropy LGLZTSNO electrolyte has preferable room temperature ion conductivity, air stability, interface contact performance with lithium anode, and the ability to suppress lithium dendrites. Thanks to the improvement of electrolyte performance, the critical current density of Li/Ag@LGLZTSNO/Li symmetric cell was increased from 0.42 to 1.57 mA cm−2, and the interface area specific impedance (IASR) was reduced from 765.2 to 42.3 Ω cm2. Meanwhile, the Li/Ag@LGLZTSNO/LFP full cell also exhibits excellent rate performance and cycling performance (148 mA h g−1 at 0.1 C and 124 mA h g−1 at 0.5 C, capacity retention up to 84.8% after 100 cycles at 0.1 C), showing the application prospects of high-entropy LGLZTSNO solid electrolyte in high-performance all solid state lithium batteries.

Li Stripping Behavior of Anode‐Free Solid‐State Batteries Under Intermittent‐Current Discharge Conditions

AbstractAnode‐free manufacturing holds promise to enable high energy densities and lower Lithium (Li)‐metal solid‐state batteries (LMSSBs). Nevertheless, in contrast to thick Li foil (>50 µm), the stripping capacity of in situ‐formed Li (10–30 µm) is limited due to diminished creep flow, resulting in reduced accessible capacity. This study explores the correlation between stripping capacity and surface roughness of garnet Li7La3Zr2O12 (LLZO) solid electrolyte. The results reveal that stripping capacity can be enhanced through the surface modification of solid electrolytes. Additionally, this study scrutinizes the stripping behavior of in situ Li under intermittent‐current discharge conditions, which are more relevant to the operational conditions of electric vehicles (EVs). It is demonstrated that, when compared to constant‐current stripping, intermittent‐current stripping effectively suppresses void formation and enhances the stripping capacity of in situ Li by 40%. It is considered that the intermittent current inhibits the accumulation of Li vacancies, thereby delaying the void formation. These findings provide valuable insights into the development of high‐performance anode‐free LMSSBs for EVs.

Preparation and performance of highly-conductive dual-doped Li7La3Zr2O12 solid electrolytes for thermal batteries

Garnet Li7La3Zr2O12 (LLZO) electrolytes have been recognized as a promising candidate to replace liquid/molten-state electrolytes in battery applications due to their exceptional performance, particularly Ga-doped LLZO (LLZGO), which exhibits high ionic conductivity. However, the limited size of the Li+ transport bottleneck restricts its high-current discharging performance. The present study focuses on the synthesis of Ga3+ and Ba2+ co-doped LLZO (LLZGBO) and investigates the influence of doping contents on the morphology, crystal structure, Li+ transport bottleneck size, and ionic conductivity. In particular, Ga0.32Ba0.15 exhibits the highest ionic conductivity (6.11E-2 S cm−1 at 550 °C) in comparison with other compositions, which can be attributed to its higher-energy morphology, larger bottleneck and unique Li+ transport channel. In addition to Ba2+, Sr2+ and Ca2+ have been co-doped with Ga3+ into LLZO, respectively, to study the effect of doping ion radius on crystal structures and the properties of electrolytes. The characterization results demonstrate that the easier Li+ transport and higher ionic conductivity can be obtained when the electrolyte is doped with larger-radius ions. As a result, the assembled thermal battery with Ga0.32Ba0.15-LLZO electrolyte exhibits a remarkable voltage platform of 1.81 V and a high specific capacity of 455.65 mA h g−1 at an elevated temperature of 525 °C. The discharge specific capacity of the thermal cell at 500 mA amounts to 63% of that at 100 mA, showcasing exceptional high-current discharging performance. When assembled as prototypes with fourteen single cells connected in series, the thermal batteries deliver an activation time of 38 ms and a discharge time of 32 s with the current density of 100 mA cm−2. These findings suggest that Ga, Ba co-doped LLZO solid-state electrolytes with high ionic conductivities holds great potential for high-capacity, quick-initiating and high-current discharging thermal batteries.

Investigating the Effect of Co-doping on Structural and Electrical Properties of Li7La3Zr2O12 Solid Electrolyte

Garnet-type Li<sub>7</sub>La<sub>3</sub>Zr<sub>2</sub>O<sub>12</sub> (LLZO) has garnered significant attention for solid-state Li-ion batteries due to its commendable Li-ion conductivity, wide electrochemical window, and exceptional chemical and thermal stability. Nonetheless, challenges related to structural instability and air stability persist, impeding its market expansion. Herein, we explore the effects of co-doping (Ga with Sc/Y/In/Er) on the crystal structure and Li-ion conductivity of LLZO through x-ray diffraction (XRD), scanning electron microscope (SEM), and AC impedance measurements. XRD refinement confirms the formation of pure-phase samples with a cubic crystal structure. SEM analysis reveals a dense microstructure with grain sizes exceeding 200 μm and a relative density approaching∼94%. While Ga/Sc and Ga/Y doped LLZO exhibit relatively lower Li-ion conductivity, Ga/Er and Ga/In doped samples demonstrate high conductivity more than 1 mS/cm at room temperature (25°C). Thus, the judicious selection of dopants emerges as an effective strategy for enhancing conductivity in all-solid-state batteries.

Li5AlO4-Assisted Low-Temperature Sintering of Dense Li7La3Zr2O12 Solid Electrolyte with High Critical Current Density.

In recent years, solid electrolytes (SEs) have been developed a lot due to the superior safety of solid-state batteries (SSBs) upon liquid electrolyte-based commercial batteries. Among them, garnet-type Li7La3Zr2O12 (LLZO) is one of the few SEs that is stable to lithium anode with high Li+ conductivity and the feasibility of preparation under ambient air, which makes it a promising candidate for fabricating SSBs. However, high sintering temperature (>1200 °C) prevents its large-scale production, further hindering its application. In this work, the Li5AlO4 sintering aid is proposed to decrease the sintering temperature and modify the grain boundaries of LLZO ceramics. Li5AlO4 generates in situ Li2O atmosphere and molten Li-Al-O compounds at relatively low temperatures to facilitate the gas-liquid-solid material transportation among raw LLZO grains, which decreases the densification temperature over 150 °C and strengthens the grain boundaries against lithium dendrites. As an example, Ta-doped LLZO ceramics without excessive Li sintered with 2 wt % Li5AlO4 at 1050 °C delivered high relative density > 94%, an ionic conductivity of 6.7 × 10-4 S cm-1, and an excellent critical current density (CCD) of 1.5 mA cm-2 at room temperature. In comparison, Ta-doped LLZO with 15% excessive Li sintered at 1200 °C delivered low relative density < 89%, a low ionic conductivity of ∼2 × 10-4 S cm-1, and a poor CCD of 0.5 mA cm-2. Li symmetric cells and Li-LFP full cells fabricated with Li5AlO4-assised ceramics were stably cycled at 0.2 mA cm-2 over 2000 h and at 0.8C over 100 cycles, respectively.

First-principles evaluation of dopant impact on structural deformability and processability of Li7La3Zr2O12.

Li7La3Zr2O12 (LLZO) and related ceramic solid electrolytes feature excellent stability and reasonable ionic conductivity, but processing remains challenging. High-temperature co-sintering is required for successful integration with the electrode, which is energetically costly and can lead to unacceptable cathode degradation. The introduction of dopants can promote lower-temperature processing by improving deformability and disrupting lattice integrity; however, an unbiased, systematic study correlating these properties to the dopant chemistry and composition is lacking. Here, we rely on a set of static and dynamic metrics derived from first-principles simulations to estimate the impact of doping on LLZO processability by quantifying LLZO structural deformability. We considered three distinct dopants (Al, Ba, and Ta) as representatives of substitutional incorporation on Li, La, and Zr sites. Our descriptors indicate that doping in general positively impacts lattice deformability, although significant sensitivities to dopant identity and concentration are observed. Amongst the tested dopants, Al doping (on the Li site) appears to have the greatest impact, as signaled across nearly the entire set of computed features. We suggest that these proxy descriptors, once properly calibrated against well-controlled experiments, could enable the use of first-principles simulations to computationally screen new ceramic electrolyte compositions with improved processability.

Synthesis of Garnet-type Solid Electrolyte for All-Solid-State Battery Application

The Ga-doped Li7La3Zr2O12 (LLZO) Solid State Electrolyte (SSE) has been synthesized via solid-state reaction. The structural study of the SSE was conducted with the help of X-ray diffraction and the Rietveld method. The SSE crystallizes in the Li6.25Ga0.15La2.90Zr2O12 phase with cubic space group number 220 and unit cell parameter 13.02081 Å, and La2Zr2O7 impurity phase with cubic space group number 227 and unit cell parameter 10.79475 Å. Obtained lattice planes in the refinement were confirmed with the help of TEM. The core of the Li-ion migration channel has been defined as the loop formed by the Li32, Li1, Li2, and Li22 sites with minimal Li...Li distance and occupational disorganization of the Ga-doped LLZO SSE. The electron density plots of the Li6.25Ga0.15La2.90Zr2O12 phase have shown maximum distribution of electrons inside the unit cell for lanthanum atoms. XPS confirmed the presence of all the precursors i.e., Li, La, Zr, Ga, and O in the synthesized compound. The elemental composition was confirmed with the help of EDX. In the direct current charge-discharge behavior of the Li symmetric cell no voltage breakdown was observed even at 6 mAcm‑2 current density and after 400 charge/discharge cycles for over 200 hours.

Effect of depth of discharge (DOD) on cycling in situ formed Li anodes.

Lithium-metal solid-state batteries (LMSSBs) have garnered immense interest due to their potential to enhance safety and energy density compared to traditional Li-ion batteries. The anode-free approach to manufacturing Li-metal anodes could provide the additional benefit of reducing cost. However, a lack of understanding of the mechano-electrochemical behavior related to the cycling of in situ formed Li anodes remains a significant challenge. To bridge this knowledge gap, this work aims to understand the cycling behavior of in situ formed Li anodes on garnet Li7La3Zr2O12 (LLZO) solid-electrolyte as a function of the depth of discharge (DOD). The results of this study show that cycling in situ formed Li of 3 mA h cm-2 with a DOD of 66% leads to unstable cycling, while cycling with a DOD of 33% exhibits stable cycling. Furthermore, we observed interfacial deterioration and inhomogeneity of in situ formed Li anodes during cycling with a DOD of 66%. This study provides mechanistic insight into the factors that affect stable cycling that can help guide approaches to improve the cycling behavior of in situ formed Li anodes.

(Digital Presentation) Crystal Structure Study of Ga-Substituted Li7La3Zr2O12 solid State Electrolyte with the Help of Rietveld Refinement

The Ga-doped Li7La3Zr2O12 (LLZO) Solid State Electrolyte (SSE) has been looked into with the help of X-ray diffraction and its structure has been successfully refined by the Rietveld method. The SSE crystallizes in the Li6.25Ga0.15La2.90Zr2O12 phase with cubic space group number 220 and unit cell parameter 13.02081 Å, and La2Zr2O7 phase with cubic space group number 227 and unit cell parameter 10.79475 Å. With 113 total reflections, the structural parameters of both the phases conversed to Rp = 13.5, Rexp = 14.16, Rwp = 18.5 and the goodness of fit i.e., χ2 was obtained as 1.74. The core of the Li-ion migration channel has been defined as the loop formed by the Li32, Li1, Li2, and Li22 sites with minimal Li...Li distance and occupational disordering of the Ga-doped LLZO SSE. The electron density plots of Li6.25Ga0.15La2.90Zr2O12 phase has shown maximum distribution of electrons inside the unit cell for lanthanum atoms. XPS confirmed the presence of all the precursors in the synthesized compound. Figure 1

Improvement of Ionic Conductivity in Li7La3Zr2O12 (LLZO) Solid Electrolyte By Doping with Aluminum/Tungsten

Recently, there has been increasing interest in solid electrolytes, which are the most important materials in all-solid-state lithium-ion batteries. Among all solid electrolytes, garnet-type Li7La3Zr2O12 (LLZO) has been proven to be one of the most promising electrolytes due to its high Li+ conductivity, wide potential window, and electrochemical stability towards metallic lithium anode. In particular, cubic garnet-type LLZO solid electrolytes have received a lot of attention for the development of high-performance all-solid-state batteries with safety, energy density, and long cycle life. In this study, we synthesized LLZO solid electrolyte powders with garnet structure and determined the optimal composition and sintering temperature by adding Al/W to form a stable cubic phase.In this study, Al or W-doped LLZO were prepared by a post-doping method. In this process, LLZO powder was first prepared, and then mixed with Al2O3 or WO3 powders to produce doped LLZO ceramic electrolytes, respectively. During this process, the doped ions entered the LLZO lattice, increasing the lithium ion transport channels and promoting lithium ion conductivity. The sintering time, crucible, and sintering temperature were adjusted to investigate the optimal process conditions of the post-doping method. As a result, the doped solid electrolyte exhibited high lithium ion conductivity and low activation energy. Using the high lithium ion conductivity and broad electrochemical stability window of the Al or W doped LLZO SSE, the (NCM622)/(Al or W doped-LLZO) cell delivered a steady cycle for 100 cycles at 0.1C. The Al or W doped-LLZO prepared in this study showed advantages of high conductivity, simple preparation process, high reproducibility, and low cost, which provides technical support and reference for further application of garnet-type SSEs in solid-state batteries with high energy density.

The synergistic effects of dual substitution of Bi and Ce on ionic conductivity of Li7La3Zr2O12 solid electrolyte

Li7La3Zr2O12 (LLZO) is a promising solid-state electrolytes (SSE) candidate with high ionic conductivity, wide electrochemical window, good chemical stability and thermal stability. However, LLZO is unstable at room temperature and is easily converted from a cubic structure to a tetragonal structure, resulting in a decrease in ionic conductivity. Stable cubic phase LLZO can be obtained by element doping and the ionic conductivity can be improved. We found that the doping of Bi and Ce can reduce the sintering temperature and increase the ionic conductivity, among which the Li7La2.5Ce0.5Zr1.625Bi0.3O12 (LLCZBO) solid electrolyte has the highest ionic conductivity of 5.12 × 10−4 S cm−1 and the electronic conductivity of 2.72 × 10−10 at room temperature. LLCZBO prepared by sol-gel method can reduce the sintering temperature and improve the degree of densification. These results indicate that double-doped Bi and Ce is a simple and effective strategy to develop oxide solid electrolytes with high ionic conductivity.

In-doped Li7La3Zr2O12 nanofibers enhances electrochemical properties and conductivity of PEO-based composite electrolyte in all-solid-state lithium battery

Garnet type Li7La3Zr2O12 solid electrolyte exhibits excellent thermal stability and high ionic conductivity, which is an ideal solid electrolyte. However, it is found that the cubic phase is a high conductivity phase and the synthesis condition is harsh. Therefore, low temperature synthesis and partial element substitution are expected to prepare cubic phase LLZO. In this paper, the LLZO cubic phase structure is stabilized by electrospinning technology and high-priced cation substitution strategy, and the transportation efficiency of lithium ions is improved. The experimental results show that LLZO NFs inorganic filler with stable cubic phase structure is obtained when the molar amount of In3+ is 0.2. The In3+ with large ion radius replaces the Li+ inside the crystal, effectively increases the lithium vacancy concentration, and increases the Li+ transport path inside the crystal, and successfully doubles the ionic conductivity of the composite solid electrolyte at 60 °C (9.39 × 10−4 S/cm). The lithium ions migration number and electrochemical window were increased to 0.19 and 5.2 V respectively. With excellent cycle performance (60 °C), it can cycle 2000 cycles at a high rate of 0.5 C charge and discharge, and the Coulomb efficiency has been close to 100 %. Li|PL-LILZO NFs (0.2)|LFP all-solid-state lithium batteries can light small bulbs at room temperature and have practical application prospects. Therefore, in the composite electrolyte, the increase of the lithium ions pathway inside the active inorganic filler crystal will also improve the comprehensive performance of the composite electrolyte for preparation.

Inhibition of lithium dendrites by a LiPON interlayer with Li+ conductive and electron non-conductive dynamic properties based on Li7La3Zr2O12 solid electrolyte

The lithium dendrite problem of Li7La3Zr1.4Ta0.6O12 (LLZTO) solid electrolyte restricts the practical application and development of all-solid-state lithium batteries (ASSLBs). Herein, a LiPON interlayer with Li+ conductive and electron non-conductive dynamic properties is constructed at the Li/LLZTO interface. Results show that the electronic conductivity of solid electrolyte after LiPON modification decreased by nearly three orders of magnitude, indicating that it has good ability to hinder electron conduction. The interlayer enhances the wettability between the Li metal anode and LLZTO, resulting in a decrease of battery resistance from 3400 Ω to 700 Ω. The critical current density of the ASSLBs increase from 0.1 mA cm−2 to 1.2 mA cm−2 at room temperature, and the battery cycle number increase from 31 h to over 1000 h. XPS deep etching results show that the LiPON/LLZTO interface has good electrochemical stability. The Kelvin probe force microscope displays a sharp increase in potential within the LiPON interlayer, indicating its successful hindrance of electron conduction to the solid electrolyte. The effective inhibition of lithium dendrites growth is due to LiPON can promote the Li+ transmission from LLZTO solid electrolyte to Li anode, and also hinder the electron conduction to LLZTO to form lithium dendrites.

Enhancement in Li-ion conductivity through Co-doping of Ge and Ta in garnet Li7La3Zr2O12 solid electrolyte

For use as an electrolyte in All Solid State Batteries (ASSB), a solid electrolyte must possess ionic conductivity comparable to that of conventional liquid electrolytes. To achieve this conductivity range, the series Li6.8-yGe0.05La3Zr2-yTayO12 (y = 0, 0.15, 0.25, 0.35, 0.45) has been synthesized using a solid-state reaction method and studied using various characterization techniques. The highly conducting cubic phase is confirmed from XRD analysis. Structural information was collected using SEM and density measurements. The prepared ceramic sample containing 0.25 Ta, sintered at 1050 °C for 7.30 hrs, shows the maximum ionic conductivity of 6.61 x 10-4 S/cm at 25 °C. The air stability of the same ceramic has also been evaluated after exposure for 5 months. The minimum activation energy associated with the maximum conductivity of 0.25 Ta is 0.25 eV. The DC conductivity measurements were done to confirm the ionic nature of conductivity for all ceramic samples. The stable result of ionic conductivity makes the 0.25 Ta containing ceramic sample a promising candidate for solid electrolytes for ASSB applications.

Enhancing performance of all-solid-state battery by establishment of interconnected Li7La3Zr2O12 network in graphite composite anode

Garnet-type Li7La3Zr2O12 (LLZO) solid electrolytes are synthesized with interconnected and larger rounded particle morphologies using a cellulose template method and conventional solid-state reaction, respectively. The synthesized LLZOs are optimized and used as a solid electrolyte in a natural graphite (NG)-based composite anode in an all-solid-state lithium battery. For the LLZO with the interconnected particle morphology, the optimum heat-treatment temperature (900 °C) and LLZO content (30 wt%) are determined to result in higher ionic conductivity. That is, higher dispersion or good distribution of the interconnected LLZO (width of 1 μm or less) within the composite anode enables easier ionic conduction of the interconnected LLZO. The NG-based composite anode filled with interconnected LLZO shows effective improvement due to a well-controlled inner percolation structure, resulting in improved cycle stability and enhanced high-rate capability, compared with the composite anode embedded with conventional spherical-type LLZO particles.

Correlation among crystal and local structure, phase transition, and Li–ion conduction of solid electrolyte Li7La3Zr2O12

The correlation among the crystal and local structure, phase transition, and Li–ion conduction of the solid electrolyte Li7La3Zr2O12 (LLZ) was investigated by quantum beam technique. According to the results of Rietveld refinement using Neutron diffraction data, the Li (8a) and Li (16f) sites have the deficiency of approximately 3∼5% in LLZ. These results of Li site occupancies were adopted to the Rietveld refinements with in situ Synchrotron X–ray Diffraction's (SR–XRD) from 300 K to 1000 K. The phase transition from the tetragonal to cubic phase was observed in in situ SR–XRD. The results of Rietveld refinements with in situ SR–XRD showed the coexistence of the tetragonal and cubic phase from 860 K to 880 K. The Li–ion conduction was discussed with respect to the atomic displacement parameters, electric density estimated by Rietveld refinements and Maximum Entropy Method (MEM) analysis, and local structure estimated by X–ray Absorption Spectra (XAS) and Pair Distribution Function (PDF) analysis. The Li–ion diffusion mechanism was discussed with crystal and local structures at high temperatures of LLZ. In particular, the coexistence of tetragonal phase at the phase transition, the bond of the Li and oxide at tetragonal phase, and the low symmetry of ZrO6 up to about 930 K are thought to inhibit Li diffusion.

First-principles calculations and Yb3+ doping effects study of garnet-type solid state electrolytes

Garnet-type solid state electrolyte Li7La3Zr2O12 (LLZO) plays a critical role in enhancing the safety of all solid-state lithium batteries, but its practical applications have been seriously limited by its poor ionic conductivity at room temperature. Elemental doping is an effective strategy to address this issue and the influence of Yb3+ doping on LLZO performance was investigated in this study. The doping site of Yb3+ in LLZO was determined by first-principles calculations based on DFT for the first time, and the results revealed that the Yb3+ doping position was La3+ site. A series of Li7La3-xYbxZr2O12 (x = 0.02, 0.04, 0.06, 0.15,0.30, LLYZO) were successfully produced by solid-state reaction route. It was found that the Yb3+ doping strategy not only enhanced the ion conductivity, but also was beneficial to inhibit the abnormal grain growth by forming LiYbO2 second phase and accelerate the sintering process. The LLYZO (x = 0.15) ceramic sintered at 1200 °C for 15 h shows a highest conductivity of 2.53× 10−4 S·cm−1, the lowest activation energy of 0.294 eV and a relative density of 90.2%.

Solving the Li7La3Zr2O12 electrochemical stability window puzzle

The use of ceramic solid electrolytes (SEs) to produce all-solid-state lithium batteries (ASSLBs) can overcome the safety issues related to conventional liquid electrolytes and enable Li batteries to operate at high voltage, therefore producing high power density. To make this happen, one of the most crucial requirements for the SE is to possess a large electrochemical stability window (ESW). Li7La3Zr2O12 (LLZO) solid electrolyte has attracted a lot of attention given its high ionic conductivity and because it was first reported with a very wide ESW (0–9 V vs. Li+/Li). It was not until recently that this value of the ESW was challenged, mainly proving that the oxidation of LLZO happened at a much earlier potential than 9 V. The present manuscript describes a methodology to accurately determine the ESW of doped M:LLZO (M = Al, Ta and Nb). To do so, M:LLZO is processed into a composite with gold powder to allow a large contact surface between SE and conductive gold particles, which maximizes the redox currents. To characterize the ESW, potentiostatic intermittent titration technique (PITT) was used. PITT allowed to remain close to the thermodynamic equilibrium to observe the redox currents. The ESW of M:LLZO was found to be [1.65–3.7] V vs. Li+/Li for all three dopants. The reduction reaction occurring at 1.65 V was evidenced for Al:LLZO through ex situ7Li nuclear magnetic resonance (NMR) and operando powder X-ray diffraction (PXRD) analyses.

Acid Leaching of Al- and Ta-Substituted Li7La3Zr2O12 (LLZO) Solid Electrolyte

Solid-state batteries (SSBs) are promising next-generation batteries due to their potential for achieving high energy densities and improved safety compared to conventional lithium-ion batteries (LIBs) with a flammable liquid electrolyte. Despite their huge market potential, very few studies have investigated SSB recycling processes to recover and reuse critical raw metals for a circular economy. For conventional LIBs, hydrometallurgical recycling has been proven to be able to produce high-quality products, with leaching being the first unit operation. Therefore, it is essential to establish a fundamental understanding of the leaching behavior of solid electrolytes as the key component of SSBs with different lixiviants. This work investigates the leaching of the most promising Al- and Ta-substituted Li7La3Zr2O12 (LLZO) solid electrolytes in mineral acids (H2SO4 and HCl), organic acids (formic, acetic, oxalic, and citric acid), and water. The leaching experiments were conducted using actual LLZO production waste in 1 M of acid at 1:20 S/L ratio at 25 °C for 24 h. The results showed that strong acids, such as H2SO4, almost completely dissolved LLZO. Encouraging selective leaching properties were observed with oxalic acid and water. This fundamental knowledge of LLZO leaching behavior will provide the basis for future optimization studies to develop innovative hydrometallurgical SSB recycling processes.