Lithium lanthanum zirconium oxide LLZO
Li7La3Zr2O12 · cubic
LLZO (Li7La3Zr2O12) is a garnet-structure oxide that conducts lithium ions in its cubic form and is studied as a solid electrolyte to replace liquid electrolytes in lithium batteries.
Evidence level
2 of 5
Lab-measured
- 0Predicted only. No one has made it, or no measurement exists.
- 1Calculated. Only calculated or predicted values from sources.
- 2Lab-measured. Measured properties with their conditions stated.
- 3Space-relevant tests. Measured in conditions relevant to space, such as vacuum or atomic oxygen.
- 4Ground-qualified. Qualified for an application on the ground.
- 5Flown or field-proven. Flight or field results exist.
Conductivity
5×10^-4 S/cm
Stiffness
147 to 154 GPa
Window
0 to 6 V vs Li/Li+
Stability against lithium
8.2 kJ/mol
Recipe, share of the weight
- Li 5.8%Lithium
- La 49.6%Lanthanum
- Zr 21.7%Zirconium
- O 22.9%Oxygen
Best for
Solid electrolytes for lithium-metal batteries that need a stiff, non-flammable oxide that is stable against lithium
Weakest at
Low ionic conductivity compared with liquid electrolytes, moisture sensitivity, and high density
Risk at a glance
- People None found. Corrosive powder; avoid dust and skin contact
- If it fails High. Lithium penetration through the electrolyte
- Corrosion Moderate. Air exposure forms a lithium carbonate skin on LLZO, which lowers its conductivity.
Quick facts: LLZO
| Property | Value | Basis |
|---|---|---|
| Density | 5.09 g/cm³ | 1 sourced value |
| Young's modulus | 140 to 154 GPa | 2 sourced values across conditions |
What is the density of Lithium lanthanum zirconium oxide (LLZO)?
Lithium lanthanum zirconium oxide (LLZO) has a density of 5.09 g/cm³. The source and test conditions are listed in the properties table on this page.
What is the Young's modulus of Lithium lanthanum zirconium oxide (LLZO)?
Lithium lanthanum zirconium oxide (LLZO) has a Young's modulus of 140 to 154 GPa. The range covers 2 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What is Lithium lanthanum zirconium oxide (LLZO) used for?
Uses recorded in the sources include All-solid-state lithium-metal cell (laboratory, composite cathode); Solid-state Li/LLZO/LCO battery (modelling study).
Why it exists
LLZO is a garnet-structure oxide that conducts lithium ions in its cubic form. It is studied as a solid electrolyte to replace the flammable liquid electrolytes of commercial lithium-ion cells. Its bulk conductivity at room temperature is about 0.0005 S/cm for cubic material, and doped versions reach about 1 mS/cm. Its lower conductivity compared with liquid electrolytes (about 10 mS/cm, as quoted by one feasibility study) is the main reason it has not replaced them outright. Thermodynamically, lithium metal does not react with it, which makes it a candidate for lithium-metal anodes.
Where it's used
Laboratory all-solid-state lithium-metal cells
A Nature Communications study reports an all-solid-state cell with a 5 mAh/cm2 composite cathode and a co-doped LLZO electrolyte, delivering a cumulative 4000 mAh/cm2 at 3 mA/cm2. The authors call it the highest cycling figure they know of for LLZO-based lithium-metal cells.
Feasibility modelling for solid-state batteries
A Scientific Reports model asks whether LLZO can be the only electrolyte in a solid-state battery. Its density of 5.1 g/cm3 and lower conductivity than liquid electrolytes raise doubts about matching the energy density of conventional lithium-ion cells.
Recipe
Li7La3Zr2O12
Atomic weights are IUPAC standard values (iupac-atwt). LLZO is a lithium lanthanum zirconium oxide with the formula Li7La3Zr2O12. It is made by solid-state reaction of lithium carbonate, lanthanum oxide and zirconium dioxide; the paper gives the reaction 4 ZrO2 + 3 La2O3 + 7 Li2CO3 gives 2 Li7La3Zr2O12 + 7 CO2.
| Ingredient | Atoms per unit | Share of the weight | What it does |
|---|---|---|---|
| Lithium Li | 7 | 5.8% | The mobile ion. Lithium moves through the garnet framework as the cell charges and discharges. |
| Lanthanum La | 3 | 49.6% | Sits on the larger sites of the garnet framework and gives the structure its rigidity. |
| Zirconium Zr | 2 | 21.7% | Forms the zirconate octahedra that hold the framework together. Substituting part of it with Ta or Al is the usual way to stabilise the cubic phase. |
| Oxygen O | 12 | 22.9% | The oxide framework. Oxygen is the anion that the lithium ions pass between. |
Weight shares are calculated from standard atomic weights.
What it can do
Conductivity
5×10^-4 S/cm
measured
Cubic LLZO conducts about 0.0005 S/cm at room temperature, and doped versions reach about 1 mS/cm. The tetragonal modification conducts about two orders of magnitude less, so the cubic phase must be stabilised.
Stiffness
147 to 154 GPa
measured
Nanoindentation gives a Young's modulus of 147 to 154 GPa for Al- and Ta-doped LLZO. The shear modulus of about 56 to 61 GPa is far above the roughly 8.5 GPa the paper cites as a minimum for suppressing dendrites.
Window
0 to 6 V vs Li/Li+
measured
The electrochemical operation window is quoted as 0 to 6 V vs Li/Li+ in one feasibility paper, which makes LLZO a wide-window oxide electrolyte.
Stability against lithium
8.2 kJ/mol
worked out from the formula
The Gibbs energy of the reaction with lithium metal is +8.2 kJ/mol, so the paper calls the reaction thermodynamically impossible. The practical problems are at the interface and in lithium penetration.
How it compares
Compared with liquid organic electrolytes (about 10 mS/cm at room temperature), LLZO conducts far less, and its density of about 5.1 g/cm3 is high. Its shear modulus is far stiffer than that of lithium metal. Lithium phosphate (Li3PO4) and lithium orthosilicate (Li4SiO4) are the other lithium oxyanion solid electrolytes. The pure phases conduct poorly, and mixed compositions improve conductivity; the abstract was not accessible when this profile was written, so no values are given here. The table compares LLZO's own published values.
The same measurements for each material, so you can compare them. Each row names the key condition under the value; the full conditions and methods are in the numbered notes under Technical details. Other materials are shown beside it; each was measured under its own conditions, so open its page before comparing closely. Compare every grade in the family.
| Measurement | LLZO | LiPF6 | EC | PC |
|---|---|---|---|---|
| Capacity and energy | ||||
| Gibbs energy of reaction with lithium metal | 8.2 kJ/mol10 | no data | no data | no data |
| Physical and electrical | ||||
| Density of Li7La3Zr2O12 | 5.09 g/cm³1 | 1.5 g/cm³ | 1.321 g/cm³ | 1.205 g/cm³ |
| Density of a typical sintered Al-doped LLZO pellet | 92 % of theoretical2 | no data | no data | no data |
| Bulk Li-ion conductivity of cubic LLZO at room temperature | 5×10^-4 S/cm3 | 10.8 to 12.9 mS/cm | no data | no data |
| Bulk Li-ion conductivity of doped LLZO at room temperature | 1 mS/cm4 | 10.8 to 12.9 mS/cm | no data | no data |
| Liquid organic electrolyte, for comparison | 10 mS/cm5 | 10.8 to 12.9 mS/cm | no data | no data |
| Other measurements | ||||
| Young's modulus by nanoindentation (Al- and Ta-doped LLZO) | 147 to 154 GPa6 | no data | no data | no data |
| Young's modulus by impulse excitation (dense LLZO) | 140 to 146 GPa7 | no data | no data | no data |
| Isotropic shear modulus, calculated and measured | 56 to 61 GPa8 | no data | no data | no data |
| Electrochemical operation window vs Li/Li+ | 0 to 6 V vs Li/Li+9 | no data | no data | no data |
| Standard entropy at 298 K | 362.3 J/(mol*K)11 | no data | no data | no data |
Why choose it, and why not
Good for
- Stiffness and chemical stability against lithium metal, both in the cited measurements and in the thermodynamic values.
- Wide electrochemical window of 0 to 6 V vs Li/Li+, as quoted by the papers.
Watch out for
- Low conductivity compared with liquid electrolytes; the cubic phase must be stabilised by doping, and the tetragonal phase conducts much less.
- Moisture and carbon dioxide form a surface layer that raises interfacial resistance.
- Lithium can penetrate the electrolyte through surface cracks and cause a short circuit, a failure mode the paper cites.
LLZO is a promising, stiff, stable oxide electrolyte for lithium-metal solid-state cells. Its conductivity and surface chemistry are the limits, and the laboratory cell data are the authors' own.
Technical details
For scientists and researchers. Everything above comes from the record below: every number with its method, its conditions and its source.
Cell-level benchmarks
Values for finished cells. These vary by manufacturer, so read the conditions in the notes. Other materials are shown beside it; each was measured under its own conditions, so open its page before comparing closely. Compare every grade in the family.
Notes
The method, full conditions and any caveat for the numbered rows above.
| # | Measurement | Method | Conditions | Caveat |
|---|---|---|---|---|
| 1 | Density of Li7La3Zr2O12 | Density quoted in the paper from its reference 58; the paper does not measure it | basis value quoted by the paper for LLZO when it computed the molar volume (165.0 cm3/mol)phase garnet, cubic composition Li7La3Zr2O12 | — |
| 2 | Density of a typical sintered Al-doped LLZO pellet | Stated by the paper for a typical pellet made in its lab; not a general figure for all LLZO | form dense sintered pellet, Al-doped LLZOreference theoretical density | The paper says "about 92%", so treat the value as approximate. |
| 3 | Bulk Li-ion conductivity of cubic LLZO at room temperature | Typical value quoted from earlier work (the paper's reference 6) and written here as 0.0005 S/cm | phase cubic Li7La3Zr2O12 (c-LLZO)temperature room temperatureunit in source 5 x 10-4 S cm-1 | The same paper says the tetragonal modification is lower by two orders of magnitude, with no absolute value given. |
| 4 | Bulk Li-ion conductivity of doped LLZO at room temperature | Value stated in the introduction of a Nature Communications paper, citing earlier work | material doped LLZO (Al, Ta or co-doped), room temperature | A best-case doped figure from the literature, not a single measurement made by the paper. |
| 5 | Liquid organic electrolyte, for comparison | Comparison value stated in a Scientific Reports feasibility paper | material liquid electrolytes (organic solvent based)temperature room temperatureapproximate ca. 10 mS cm-1 as printed | — |
| 6 | Young's modulus by nanoindentation (Al- and Ta-doped LLZO) | Nanoindentation measurements reported by the paper and compared with its first-principles calculations | form dense Al- and Ta-doped LLZO compositionsmethod nanoindentationtemperature room temperature | — |
| 7 | Young's modulus by impulse excitation (dense LLZO) | Impulse excitation measurements reported by the paper for dense specimens | form polycrystalline specimens of relative density above 98%method impulse excitation (acoustic resonance) | — |
| 8 | Isotropic shear modulus, calculated and measured | Range stated in the abstract and results of the paper | form Al- and Ta-doped LLZOmethod first-principles calculation and resonance measurements agree | The paper compares this shear modulus with about 8.5 GPa, the value it cites as a minimum for suppressing dendrite initiation. |
| 9 | Electrochemical operation window vs Li/Li+ | Window stated in a Scientific Reports paper; the other study does not give a single figure | material cubic LLZOreference Li/Li+ | Reported window ranges differ between studies; this profile gives only the 0 to 6 V range printed in the two papers. |
| 10 | Gibbs energy of reaction with lithium metal | Calculated by the paper from its formation enthalpy and entropy data; the paper calls the reaction thermodynamically impossible | temperature 298 Kreaction Li7La3Zr2O12 with lithium metal (paper's reaction equation 23)sign positive means the reaction is not favourable | — |
| 11 | Standard entropy at 298 K | Value stated by the paper from its calorimetry measurements | temperature 298 Kbasis standard state | — |
| 12 | Cumulative areal capacity of an all-solid-state Li-metal cell | Laboratory cell cycling reported by the paper's authors | cell all-solid-state cell with a 5 mAh/cm2 composite cathode and co-doped LLZO electrolyterate 3 mA/cm2cycling cumulative capacity of deposited lithium over cycling | The paper calls this the highest cycling figure reported for LLZO lithium-metal batteries; that is the authors' own claim. |
Corrosion and compatibility
What happens when it meets other materials and environments.
| Environment | Concern | What happens |
|---|---|---|
| Moist air and carbon dioxide (ambient exposure) | moderate | Air exposure forms a lithium carbonate skin on LLZO, which lowers its conductivity.1 |
| Contact with lithium metal | low | Lithium metal does not react with LLZO in thermodynamic terms, but interface and penetration problems remain.2 |
| Dry storage in a closed container | low | The powder is moisture sensitive and needs dry storage.3 |
| # | Environment | Details | Test conditions |
|---|---|---|---|
| 1 | Moist air and carbon dioxide (ambient exposure) | Lithium ions near the surface are exchanged for protons from moisture; the resulting LiOH reacts with CO2 to form Li2CO3. The surface lattice shrinks and loses lithium. Heating at 250 degC under an inert atmosphere reverses these reactions, and treated samples showed much lower interfacial impedance than air-exposed ones. | exposure polished LLZO pellet exposed to air for about a week, probed by grazing-incidence X-ray methodsdopant Al-substituted LLZO |
| 2 | Contact with lithium metal | The reaction of LLZO with lithium metal has a positive Gibbs energy (8.2 kJ/mol), so the paper calls it thermodynamically impossible. The Nature Communications paper still names chemical compatibility with lithium as the factor that controls long-term stability, and treats the interface as a limit. | temperature 298 K for the thermodynamic valuebasis thermodynamic result plus lab cycling of Li-metal cells |
| 3 | Dry storage in a closed container | The supplier safety data sheet describes the material as moisture sensitive and advises storage under dry inert gas, away from water and oxidising agents. Surface reaction with moisture is the main ageing route described for LLZO. | storage tightly closed container, dry inert gas |
Risks and side effects
Hazards to people, what happens when a cell overheats, and how the material is handled and stored.
For people
The supplier safety data sheet classes LLZO powder as a skin corrosive and respiratory irritant.
- The powder
- Hazard statements H314 (causes severe skin burns and eye damage) and H335 (may cause respiratory irritation), with signal word Danger.
- Dust
- Precautionary statement P260 says not to breathe the dust. Use dust controls and eye protection.
Air and moisture
The concern for the material is its surface chemistry, not the health of people.
- Moist air
- Air exposure forms a lithium carbonate layer on the surface and raises interfacial resistance. Heating at 250 degC under inert gas reverses it in the laboratory tests.
Handling and storage
- Storage
- The safety data sheet calls for a cool, dry place, tightly closed containers, dry inert gas, and separation from water and oxidising agents.
Test details
The original wording and numbers from the sources, for readers who want them.
Failure risks
| Failure | Trigger and consequence |
|---|---|
| Lithium penetration through the electrolytehigh severity | Electronic conductivity of LLZO and non-uniform current at a poor Li-LLZO contactLithium can form inside the electrolyte and cause a premature short circuit; the paper cites this as a reported mechanism. |
| Crack growth at the electrolyte surfacemoderate severity | Stress concentration at the LLZO surface during cyclingCracks can propagate and let lithium through; the paper cites this as a reported mechanism. |
Side effects on surrounding parts
| Affects | Effect |
|---|---|
| Operators handling powder | Fine powder can irritate the airways and damage the eyes and skin on contact. |
Handling and storage
- Store in a cool, dry place in tightly closed containers, under dry inert gas, away from water and oxidising agents.
- Handle the powder under inert gas where the process allows, and keep it dry.
Mitigations
- Heating at 250 degC under an inert atmosphere reverses the moisture and CO2 surface reaction and restores low interfacial impedance.
- Bulk doping together with a protonation or etching interface treatment improves the compatibility of LLZO with lithium metal.
Supply and geography
How common the raw materials are and where they come from.
Lithium (lithium carbonate precursor)
- Top producers (2025)
- Australia 31.7%, China 21.4%, Chile 19.3%, Zimbabwe 9.7%, Argentina 7.9%
- Recycling
- USGS: construction of lithium battery recycling plants continued throughout 2025.
Lanthanum (as rare earths)
- Top producers (2025)
- China 69.2%, United States 13.1%, Australia 7.4%, Burma 5.6%
- Recycling
- USGS: limited quantities of rare earths were recovered from batteries, permanent magnets and fluorescent lamps.
- Substitutes
- USGS: substitutes are available for many applications but generally are less effective.
Zirconium (zirconium mineral concentrates)
- Top producers (2025)
- Australia 33.3%, South Africa 22.5%, China 8.3%
- Recycling
- USGS: companies in Oregon and Utah recycled zirconium from new scrap generated during metal production.
Documents
Datasheets, safety data sheets, papers and standards you can open.
Full record
The complete spore, as stored. Free to reuse under CC-BY-4.0. Images keep the licence shown with each one.
Show the full YAML
spore: profile
id: llzo
spore_version: 0.2
family: lithium
name: Lithium lanthanum zirconium oxide
abbreviation: LLZO
role: solid electrolyte
category: energy
type: electrolytes
summary: |
LLZO (Li7La3Zr2O12) is a garnet-structure oxide that conducts lithium ions in its cubic form and is studied as a solid electrolyte to replace liquid electrolytes in lithium batteries. Its room-temperature bulk conductivity is about 0.0005 S/cm, rising to about 1 mS/cm in doped versions. It is dense, mechanically stiff (Young's modulus about 140 to 154 GPa), and chemically stable against lithium metal in thermodynamic terms, but it reacts with moist air and carbon dioxide to form a lithium carbonate surface layer.
best_for: Solid electrolytes for lithium-metal batteries that need a stiff, non-flammable oxide that is stable against lithium
weakest_at: Low ionic conductivity compared with liquid electrolytes, moisture sensitivity, and high density
identity:
formula: Li7La3Zr2O12
crystal_system: cubic (garnet-type; a tetragonal modification also exists with much lower conductivity)
source: pmc8707787
where: Introduction (cubic and tetragonal modifications of Li7La3Zr2O12)
tags:
environments: []
stresses: []
applications:
- batteries
properties:
- benchmark: density
label: Density of Li7La3Zr2O12
value: 5.09
unit: g/cm3
scope: material
conditions:
basis: value quoted by the paper for LLZO when it computed the molar volume (165.0 cm3/mol)
phase: garnet, cubic composition Li7La3Zr2O12
method: Density quoted in the paper from its reference 58; the paper does not measure it
status: calculated
source: pmc8746261
where: Section 3 (molar volume calculation), density values for Li2CO3, La2O3, ZrO2 and Li7La3Zr2O12
- benchmark: relative_density
label: Density of a typical sintered Al-doped LLZO pellet
value: 92
unit: '% of theoretical'
scope: material
conditions:
form: dense sintered pellet, Al-doped LLZO
reference: theoretical density
method: Stated by the paper for a typical pellet made in its lab; not a general figure for all LLZO
status: ground
note: The paper says "about 92%", so treat the value as approximate.
source: cheng2018
where: Results, first paragraph (SEM and density of polished pellets)
- benchmark: ionic_conductivity
label: Bulk Li-ion conductivity of cubic LLZO at room temperature
value: 0.0005
unit: S/cm
scope: material
conditions:
phase: cubic Li7La3Zr2O12 (c-LLZO)
temperature: room temperature
unit_in_source: 5 x 10-4 S cm-1
method: Typical value quoted from earlier work (the paper's reference 6) and written here as 0.0005 S/cm
status: ground
note: The same paper says the tetragonal modification is lower by two orders of magnitude, with no absolute value given.
source: pmc8707787
where: Introduction, paragraph on the conductivity of c-LLZO and t-LLZO
- benchmark: ionic_conductivity
label: Bulk Li-ion conductivity of doped LLZO at room temperature
value: 1
unit: mS/cm
scope: material
conditions:
material: doped LLZO (Al, Ta or co-doped), room temperature
method: Value stated in the introduction of a Nature Communications paper, citing earlier work
status: ground
note: A best-case doped figure from the literature, not a single measurement made by the paper.
source: pmc8986853
where: Introduction (first paragraph)
- benchmark: ionic_conductivity
label: Liquid organic electrolyte, for comparison
value: 10
unit: mS/cm
scope: material
conditions:
material: liquid electrolytes (organic solvent based)
temperature: room temperature
approximate: ca. 10 mS cm-1 as printed
method: Comparison value stated in a Scientific Reports feasibility paper
status: ground
source: pmc8782839
where: Introduction, comparison of LLZO with liquid electrolytes
- benchmark: elastic_modulus
label: Young's modulus by nanoindentation (Al- and Ta-doped LLZO)
value: 147
value_high: 154
bound: range
unit: GPa
scope: material
conditions:
form: dense Al- and Ta-doped LLZO compositions
method: nanoindentation
temperature: room temperature
method: Nanoindentation measurements reported by the paper and compared with its first-principles calculations
status: ground
source: cm-llzo
where: Results, nanoindentation paragraph (Young's modulus range across the Al- and Ta-doped compositions)
- benchmark: elastic_modulus
label: Young's modulus by impulse excitation (dense LLZO)
value: 140
value_high: 146
bound: range
unit: GPa
scope: material
conditions:
form: polycrystalline specimens of relative density above 98%
method: impulse excitation (acoustic resonance)
method: Impulse excitation measurements reported by the paper for dense specimens
status: ground
source: cm-llzo
where: Results, impulse excitation paragraph
- benchmark: shear_modulus
label: Isotropic shear modulus, calculated and measured
value: 56
value_high: 61
bound: range
unit: GPa
scope: material
conditions:
form: Al- and Ta-doped LLZO
method: first-principles calculation and resonance measurements agree
method: Range stated in the abstract and results of the paper
status: ground
note: The paper compares this shear modulus with about 8.5 GPa, the value it cites as a minimum for suppressing dendrite initiation.
source: cm-llzo
where: Abstract (shear moduli range) and introduction
- benchmark: electrochemical_window
label: Electrochemical operation window vs Li/Li+
value: 0
value_high: 6
bound: range
unit: V vs Li/Li+
scope: material
conditions:
material: cubic LLZO
reference: Li/Li+
method: Window stated in a Scientific Reports paper; the other study does not give a single figure
status: ground
note: Reported window ranges differ between studies; this profile gives only the 0 to 6 V range printed in the two papers.
source: pmc8782839
where: Introduction, first paragraph
- benchmark: reaction_gibbs_energy
label: Gibbs energy of reaction with lithium metal
value: 8.2
unit: kJ/mol
scope: material
conditions:
temperature: 298 K
reaction: Li7La3Zr2O12 with lithium metal (paper's reaction equation 23)
sign: positive means the reaction is not favourable
method: Calculated by the paper from its formation enthalpy and entropy data; the paper calls the reaction thermodynamically impossible
status: calculated
source: pmc8746261
where: Results, Gibbs free energy for the reaction with lithium (Delta-r G LLZO/Li)
- benchmark: standard_entropy
label: Standard entropy at 298 K
value: 362.3
unit: J/(mol*K)
scope: material
conditions:
temperature: 298 K
basis: standard state
method: Value stated by the paper from its calorimetry measurements
status: ground
source: pmc8746261
where: Results, thermodynamic data (S0 298)
- benchmark: cumulative_areal_capacity
label: Cumulative areal capacity of an all-solid-state Li-metal cell
value: 4000
unit: mAh/cm2
scope: cell
conditions:
cell: all-solid-state cell with a 5 mAh/cm2 composite cathode and co-doped LLZO electrolyte
rate: 3 mA/cm2
cycling: cumulative capacity of deposited lithium over cycling
method: Laboratory cell cycling reported by the paper's authors
status: ground
note: The paper calls this the highest cycling figure reported for LLZO lithium-metal batteries; that is the authors' own claim.
source: pmc8986853
where: Results (cumulative capacity comparison, all-solid-state cell with 5 mAh/cm2 cathode)
corrosion:
- environment: Moist air and carbon dioxide (ambient exposure)
headline: Air exposure forms a lithium carbonate skin on LLZO, which lowers its conductivity.
effect: Lithium ions near the surface are exchanged for protons from moisture; the resulting LiOH reacts with CO2 to form Li2CO3. The surface lattice shrinks and loses lithium. Heating at 250 degC under an inert atmosphere reverses these reactions, and treated samples showed much lower interfacial impedance than air-exposed ones.
rating: moderate
conditions:
exposure: polished LLZO pellet exposed to air for about a week, probed by grazing-incidence X-ray methods
dopant: Al-substituted LLZO
source: cheng2018
where: Results (GI-XRD and GI-EXAFS of pellet exposed to air for a week, Figure 2); Discussion (proton exchange and Li2CO3)
- environment: Contact with lithium metal
headline: Lithium metal does not react with LLZO in thermodynamic terms, but interface and penetration problems remain.
effect: The reaction of LLZO with lithium metal has a positive Gibbs energy (8.2 kJ/mol), so the paper calls it thermodynamically impossible. The Nature Communications paper still names chemical compatibility with lithium as the factor that controls long-term stability, and treats the interface as a limit.
rating: low
conditions:
temperature: 298 K for the thermodynamic value
basis: thermodynamic result plus lab cycling of Li-metal cells
source: pmc8746261
where: Results (Gibbs energy of reaction with lithium); Nature Communications, Abstract and Introduction
- environment: Dry storage in a closed container
headline: The powder is moisture sensitive and needs dry storage.
effect: The supplier safety data sheet describes the material as moisture sensitive and advises storage under dry inert gas, away from water and oxidising agents. Surface reaction with moisture is the main ageing route described for LLZO.
rating: low
conditions:
storage: tightly closed container, dry inert gas
source: sds-sam
where: Section 7 (storage conditions) and Section 10 (stability and incompatible materials)
risks:
hazards:
- text: 'Causes severe skin burns and eye damage (H314). May cause respiratory irritation (H335). Signal word: Danger. The supplier classes the powder under the CLP regulation.'
ghs:
- H314
- H335
source: sds-sam
where: Sections 2.1 and 2.2
- text: 'Precautionary statement P260: do not breathe dust, fume, gas, mist, vapours or spray.'
ghs: []
source: sds-sam
where: Section 2.2 (precautionary statements)
failure_risks:
- mode: Lithium penetration through the electrolyte
trigger: Electronic conductivity of LLZO and non-uniform current at a poor Li-LLZO contact
consequence: Lithium can form inside the electrolyte and cause a premature short circuit; the paper cites this as a reported mechanism.
severity: high
source: pmc8986853
where: Introduction (lithium penetration mechanisms)
- mode: Crack growth at the electrolyte surface
trigger: Stress concentration at the LLZO surface during cycling
consequence: Cracks can propagate and let lithium through; the paper cites this as a reported mechanism.
severity: moderate
source: pmc8986853
where: Introduction (lithium penetration mechanisms)
side_effects:
- text: Fine powder can irritate the airways and damage the eyes and skin on contact.
affects: Operators handling powder
source: sds-sam
where: Sections 2.1 and 4
handling:
- text: Store in a cool, dry place in tightly closed containers, under dry inert gas, away from water and oxidising agents.
source: sds-sam
where: Sections 7 and 10
- text: Handle the powder under inert gas where the process allows, and keep it dry.
source: sds-sam
where: Section 7 (handling and storage)
mitigations:
- text: Heating at 250 degC under an inert atmosphere reverses the moisture and CO2 surface reaction and restores low interfacial impedance.
source: cheng2018
where: Introduction and Results (reversal by heating)
- text: Bulk doping together with a protonation or etching interface treatment improves the compatibility of LLZO with lithium metal.
source: pmc8986853
where: Abstract and Results (interface treatment)
uses:
- application: batteries
device: All-solid-state lithium-metal cell (laboratory, composite cathode)
example: An all-solid-state cell with a 5 mAh/cm2 composite cathode and co-doped LLZO electrolyte delivered a cumulative 4000 mAh/cm2 at 3 mA/cm2, according to the paper's authors.
source: pmc8986853
where: Results (cumulative capacity comparison)
- application: batteries
device: Solid-state Li/LLZO/LCO battery (modelling study)
example: A feasibility model in Scientific Reports asks whether LLZO can serve as the only electrolyte and finds that its density (5.1 g/cm3) and lower conductivity than liquid electrolytes raise doubts about matching the energy density of Li-ion batteries.
source: pmc8782839
where: Introduction and energy-density model (3D maps in the results)
supply:
- subject: Lithium (lithium carbonate precursor)
producers:
- country: Australia
share_percent: 31.7
year: 2025
- country: China
share_percent: 21.4
year: 2025
- country: Chile
share_percent: 19.3
year: 2025
- country: Zimbabwe
share_percent: 9.7
year: 2025
- country: Argentina
share_percent: 7.9
year: 2025
recycling: 'USGS: construction of lithium battery recycling plants continued throughout 2025.'
substitutes: []
source: usgs-li
where: World Mine Production and Reserves table, 2025 (shares calculated by Space Mushroom against the 290,000 t world total, which excludes U.S. output); Recycling
- subject: Lanthanum (as rare earths)
producers:
- country: China
share_percent: 69.2
year: 2025
- country: United States
share_percent: 13.1
year: 2025
- country: Australia
share_percent: 7.4
year: 2025
- country: Burma
share_percent: 5.6
year: 2025
recycling: 'USGS: limited quantities of rare earths were recovered from batteries, permanent magnets and fluorescent lamps.'
substitutes:
- 'USGS: substitutes are available for many applications but generally are less effective.'
source: usgs-re
where: 'World Mine Production and Reserves table, 2025 (rare-earth oxide equivalent, shares calculated by Space Mushroom against the 390,000 t world total); Recycling; Substitutes; Import Sources (2021-24: China 71% of rare-earth compounds and metals)'
- subject: Zirconium (zirconium mineral concentrates)
producers:
- country: Australia
share_percent: 33.3
year: 2025
- country: South Africa
share_percent: 22.5
year: 2025
- country: China
share_percent: 8.3
year: 2025
recycling: 'USGS: companies in Oregon and Utah recycled zirconium from new scrap generated during metal production.'
substitutes: []
source: usgs-zr
where: World Mine Production table, zirconium mineral concentrates, 2025 (shares calculated by Space Mushroom against the 1,200 thousand t world total; concentrates, not zirconium metal); Recycling
media: []
documents:
- title: Superionic Solid Electrolyte Li7La3Zr2O12 Synthesis and Thermodynamics for Application in All-Solid-State Lithium-Ion Batteries (open access, Materials)
type: paper
url: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8746261/
year: 2021
- title: Influence of Powder Milling and Annealing Parameters on the Formation of Cubic Li7La3Zr2O12 Compound (Materials)
type: paper
url: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8707787/
year: 2021
- title: Garnet Electrolyte Surface Degradation and Recovery (ACS Applied Energy Materials 2018)
type: paper
url: https://perssongroup.lbl.gov/papers/cheng-2018-garnet-surface.pdf
year: 2018
- title: Elastic Properties of the Solid Electrolyte Li7La3Zr2O12 (LLZO) (Chemistry of Materials)
type: paper
url: https://public.websites.umich.edu/~djsiege/Energy_Storage_Lab/Publications_files/CM_LLZO.pdf
year: 2015
- title: On the feasibility of all-solid-state batteries with LLZO as a single electrolyte (Scientific Reports)
type: paper
url: https://pmc.ncbi.nlm.nih.gov/articles/PMC8782839/
year: 2022
- title: High-energy and durable lithium metal batteries using garnet-type solid electrolytes with tailored lithium-metal compatibility (Nature Communications)
type: paper
url: https://pmc.ncbi.nlm.nih.gov/articles/PMC8986853/
year: 2022
- title: 'Safety Data Sheet: Lithium Lanthanum Zirconate (Stanford Advanced Materials, revised 2022-11-08)'
type: sds
url: https://samaterials.com/tds/1697120079-2020-ta-doped-lithium-lanthanum-zirconate-garnet-llzo-sds.pdf
year: 2022
- title: 'Mineral Commodity Summaries 2026: Lithium'
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-lithium.pdf
year: 2026
- title: 'Mineral Commodity Summaries 2026: Rare Earths'
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-rare-earths.pdf
year: 2026
- title: 'Mineral Commodity Summaries 2026: Zirconium and Hafnium'
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-zirconium-hafnium.pdf
year: 2026
gaps:
- 'Enthalpy of formation of Li7La3Zr2O12 (about -9327.65 kJ/mol, paper Table 4) left out: the paper prints a Unicode minus sign, and verify-values does not match it. Reinstate once the sign is normalised.'
- 'No CAS number for pure Li7La3Zr2O12 was found: the supplier SDS leaves the CAS field blank and the PubChem record was not located.'
- Lithium phosphate (Li3PO4) and lithium orthosilicate (Li4SiO4) are covered only in outline in the story. The Deng et al. 2015 JACS abstract was not accessible, so no numbers are given for them.
- Vickers hardness, melting point, thermal expansion coefficient and decomposition temperature were not found in a fetched source. The SDS lists decomposition temperature as no data available.
- The SDS names the product only as lithium lanthanum zirconium oxide with no dopant stated. Hazard codes may not apply to every doped or undoped LLZO lot.
- Electrochemical window values differ between studies; only the 0 to 6 V range printed in two fetched papers is given.
- 'Critical-mineral list status for lithium, lanthanum and zirconium was not verified: the USGS PDFs consulted contain no critical-minerals list. Crustal abundance for lanthanum and zirconium was not checked.'
- Zirconium shares are for mineral concentrates, not zirconium metal, and lanthanum shares are for rare earths as a group.
- Lithium phosphate and lithium orthosilicate need their own profiles or a fetched source for numbers.
sources:
iupac-atwt:
title: Standard atomic weights (IUPAC Commission on Isotopic Abundances and Atomic Weights table)
id: IUPAC CIAAW standard atomic weights
url: https://iupac.qmul.ac.uk/AtWt/
year: 2025
kind: web
pmc8746261:
title: Superionic Solid Electrolyte Li7La3Zr2O12 Synthesis and Thermodynamics for Application in All-Solid-State Lithium-Ion Batteries
id: doi:10.3390/ma15010281 (Materials, PMC8746261)
url: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8746261/
year: 2021
kind: paper
license: CC BY 4.0 (open access, as printed on the article)
pmc8707787:
title: Influence of Powder Milling and Annealing Parameters on the Formation of Cubic Li7La3Zr2O12 Compound
id: doi:10.3390/ma14247633 (Materials, PMC8707787)
url: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8707787/
year: 2021
kind: paper
cheng2018:
title: Garnet Electrolyte Surface Degradation and Recovery
id: ACS Appl. Energy Mater. 2018, 1, 7244-7252 (Lawrence Berkeley National Laboratory)
url: https://perssongroup.lbl.gov/papers/cheng-2018-garnet-surface.pdf
year: 2018
kind: paper
cm-llzo:
title: Elastic Properties of the Solid Electrolyte Li7La3Zr2O12 (LLZO)
id: Chem. Mater. (University of Michigan, Siegel group), published 16 December 2015
url: https://public.websites.umich.edu/~djsiege/Energy_Storage_Lab/Publications_files/CM_LLZO.pdf
year: 2015
kind: paper
pmc8782839:
title: On the feasibility of all-solid-state batteries with LLZO as a single electrolyte
id: doi:10.1038/s41598-022-05141-x (Scientific Reports, PMC8782839)
url: https://pmc.ncbi.nlm.nih.gov/articles/PMC8782839/
year: 2022
kind: paper
pmc8986853:
title: High-energy and durable lithium metal batteries using garnet-type solid electrolytes with tailored lithium-metal compatibility
id: doi:10.1038/s41467-022-29531-x (Nature Communications, PMC8986853)
url: https://pmc.ncbi.nlm.nih.gov/articles/PMC8986853/
year: 2022
kind: paper
sds-sam:
title: 'Safety Data Sheet: Lithium Lanthanum Zirconate (Stanford Advanced Materials)'
id: revised 2022-11-08; CAS field blank
url: https://samaterials.com/tds/1697120079-2020-ta-doped-lithium-lanthanum-zirconate-garnet-llzo-sds.pdf
year: 2022
kind: datasheet
license: supplier document, linked not reproduced
usgs-li:
title: Mineral Commodity Summaries 2026, Lithium
id: USGS MCS 2026, February 2026
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-lithium.pdf
year: 2026
kind: report
license: public domain (USGS)
usgs-re:
title: Mineral Commodity Summaries 2026, Rare Earths
id: USGS MCS 2026
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-rare-earths.pdf
year: 2026
kind: report
license: public domain (USGS)
usgs-zr:
title: Mineral Commodity Summaries 2026, Zirconium and Hafnium
id: USGS MCS 2026
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-zirconium-hafnium.pdf
year: 2026
kind: report
license: public domain (USGS)
license: CC-BY-4.0
updated: '2026-10-26'
review:
status: draft
method: assistant
checked_values: 12
unreachable: 0
caveats: 2
note: Written by an AI assistant on 2026-10-26 from pages opened in the same run. Values are copied from the printed text; several are quoted by the papers from earlier work and are marked in method.
story:
recipe:
line: Atomic weights are IUPAC standard values (iupac-atwt). LLZO is a lithium lanthanum zirconium oxide with the formula Li7La3Zr2O12. It is made by solid-state reaction of lithium carbonate, lanthanum oxide and zirconium dioxide; the paper gives the reaction 4 ZrO2 + 3 La2O3 + 7 Li2CO3 gives 2 Li7La3Zr2O12 + 7 CO2.
parts:
- name: Lithium
symbol: Li
atoms: 7
atomic_weight: 6.94
role: The mobile ion. Lithium moves through the garnet framework as the cell charges and discharges.
- name: Lanthanum
symbol: La
atoms: 3
atomic_weight: 138.90547
role: Sits on the larger sites of the garnet framework and gives the structure its rigidity.
- name: Zirconium
symbol: Zr
atoms: 2
atomic_weight: 91.222
role: Forms the zirconate octahedra that hold the framework together. Substituting part of it with Ta or Al is the usual way to stabilise the cubic phase.
- name: Oxygen
symbol: O
atoms: 12
atomic_weight: 15.999
role: The oxide framework. Oxygen is the anion that the lithium ions pass between.
risk_groups:
- title: For people
level: 0
verdict: Corrosive powder; avoid dust and skin contact
lead: The supplier safety data sheet classes LLZO powder as a skin corrosive and respiratory irritant.
points:
- label: The powder
line: Hazard statements H314 (causes severe skin burns and eye damage) and H335 (may cause respiratory irritation), with signal word Danger.
- label: Dust
line: Precautionary statement P260 says not to breathe the dust. Use dust controls and eye protection.
- title: Air and moisture
verdict: Surface degrades in moist air
lead: The concern for the material is its surface chemistry, not the health of people.
points:
- label: Moist air
line: Air exposure forms a lithium carbonate layer on the surface and raises interfacial resistance. Heating at 250 degC under inert gas reverses it in the laboratory tests.
- title: Handling and storage
verdict: Store dry, under inert gas
points:
- label: Storage
line: The safety data sheet calls for a cool, dry place, tightly closed containers, dry inert gas, and separation from water and oxidising agents.
why: LLZO is a garnet-structure oxide that conducts lithium ions in its cubic form. It is studied as a solid electrolyte to replace the flammable liquid electrolytes of commercial lithium-ion cells. Its bulk conductivity at room temperature is about 0.0005 S/cm for cubic material, and doped versions reach about 1 mS/cm. Its lower conductivity compared with liquid electrolytes (about 10 mS/cm, as quoted by one feasibility study) is the main reason it has not replaced them outright. Thermodynamically, lithium metal does not react with it, which makes it a candidate for lithium-metal anodes.
uses:
- where: Laboratory all-solid-state lithium-metal cells
line: A Nature Communications study reports an all-solid-state cell with a 5 mAh/cm2 composite cathode and a co-doped LLZO electrolyte, delivering a cumulative 4000 mAh/cm2 at 3 mA/cm2. The authors call it the highest cycling figure they know of for LLZO-based lithium-metal cells.
- where: Feasibility modelling for solid-state batteries
line: A Scientific Reports model asks whether LLZO can be the only electrolyte in a solid-state battery. Its density of 5.1 g/cm3 and lower conductivity than liquid electrolytes raise doubts about matching the energy density of conventional lithium-ion cells.
can_do:
- label: Conductivity
benchmark: ionic_conductivity
line: Cubic LLZO conducts about 0.0005 S/cm at room temperature, and doped versions reach about 1 mS/cm. The tetragonal modification conducts about two orders of magnitude less, so the cubic phase must be stabilised.
- label: Stiffness
benchmark: elastic_modulus
value: 147 to 154 GPa
line: Nanoindentation gives a Young's modulus of 147 to 154 GPa for Al- and Ta-doped LLZO. The shear modulus of about 56 to 61 GPa is far above the roughly 8.5 GPa the paper cites as a minimum for suppressing dendrites.
- label: Window
benchmark: electrochemical_window
value: 0 to 6 V vs Li/Li+
line: The electrochemical operation window is quoted as 0 to 6 V vs Li/Li+ in one feasibility paper, which makes LLZO a wide-window oxide electrolyte.
- label: Stability against lithium
benchmark: reaction_gibbs_energy
value: 8.2 kJ/mol
line: The Gibbs energy of the reaction with lithium metal is +8.2 kJ/mol, so the paper calls the reaction thermodynamically impossible. The practical problems are at the interface and in lithium penetration.
compare: Compared with liquid organic electrolytes (about 10 mS/cm at room temperature), LLZO conducts far less, and its density of about 5.1 g/cm3 is high. Its shear modulus is far stiffer than that of lithium metal. Lithium phosphate (Li3PO4) and lithium orthosilicate (Li4SiO4) are the other lithium oxyanion solid electrolytes. The pure phases conduct poorly, and mixed compositions improve conductivity; the abstract was not accessible when this profile was written, so no values are given here. The table compares LLZO's own published values.
compare_rows:
- label: Conductivity at room temperature
benchmark: ionic_conductivity
- label: Density
benchmark: density
- label: Electrochemical window
benchmark: electrochemical_window
handling:
- The powder is corrosive to skin and eyes and irritates the airways (H314 and H335). Use dust controls, gloves and eye protection.
- Keep it dry and closed, under dry inert gas where the process allows, away from water and oxidising agents.
- Moist air forms a lithium carbonate layer on the surface. Heating at 250 degC under inert gas reverses it in the laboratory tests.
good_for:
- Stiffness and chemical stability against lithium metal, both in the cited measurements and in the thermodynamic values.
- Wide electrochemical window of 0 to 6 V vs Li/Li+, as quoted by the papers.
watch_out:
- Low conductivity compared with liquid electrolytes; the cubic phase must be stabilised by doping, and the tetragonal phase conducts much less.
- Moisture and carbon dioxide form a surface layer that raises interfacial resistance.
- Lithium can penetrate the electrolyte through surface cracks and cause a short circuit, a failure mode the paper cites.
verdict: LLZO is a promising, stiff, stable oxide electrolyte for lithium-metal solid-state cells. Its conductivity and surface chemistry are the limits, and the laboratory cell data are the authors' own.
References
Every number above carries a reference number. Click one to see the source and where in it the value comes from.