Abstract
This paper systematically reviews modern production technologies for battery-grade lithium carbonate (Li₂CO₃, purity ≥99.5%), with a focus on crystallographic control, interfacial reaction mechanisms, and process intensification strategies. Based on thermodynamic phase equilibrium and kinetic analysis, the techno-economic feasibility of different process routes is compared, and optimization directions are proposed to meet the demands of next-generation lithium battery materials.
1. Material Intrinsic Properties and Quality Control
The crystallographic characteristics of battery-grade lithium carbonate critically determine its electrochemical performance. X-ray diffraction and Rietveld refinement confirm that ideal crystals should exhibit:
- Monoclinic crystal system (space group C2/c)
- Lattice parameters: a=8.368(3) Å, b=4.965(2) Å, c=6.210(2) Å
- Lithium ion coordination number of 4 ([LiO₄] tetrahedron)
Internationally recognized technical specifications require:
- Key impurity limits (ICP-MS analysis):
∙ Na/K <50 ppm
∙ Fe <10 ppm
∙ Ca/Sr <20 ppm
∙ SO₄²⁻/Cl⁻ <30 ppm - Particle size distribution (laser diffraction):
∙ D10=1.5-2.5 μm
∙ D50=4-6 μm
∙ D90=8-12 μm
2. Lithium Extraction from Salt Lake Brines
2.1 Magnesium-Lithium Separation Science
For high-Mg brines (Mg/Li>8), recent studies indicate:
- Solvent extraction systems (TBP/FeCl₃/kerosene) achieve separation factors β(Mg/Li) up to 120
- Aluminum-based adsorbents (λ-MnO₂) exhibit lithium adsorption capacities of 6.8 mg/g (25°C)
- Crown ether derivatives (e.g., DB18C6) demonstrate Li⁺ selectivity coefficients >1000
2.2 Advances in Membrane Separation
Optimized bipolar membrane electrodialysis (BPED) parameters:
Energy consumption (E)=I⋅V⋅t/MLi
Key parameters:
- Current density (I): 250±50 A/m²
- Cell voltage (V): 3.2-3.8 V
- Li⁺ transport number: 0.88±0.03
Industrial data show this technology reduces Na content to <30 ppm.
3. Innovations in Ore-Based Lithium Extraction
3.1 Reaction Engineering in Sulfuric Acid Method
Phase transition kinetics of spodumene (α-spodumene):
dα/dt=A⋅exp(−Ea/RT)⋅(1−α)n
Critical parameters:
- β-phase formation activation energy (Ea): 215 kJ/mol
- Acidolysis reaction order (n): 1.2
- Optimal acid-to-ore ratio: 1.25:1 (mass ratio)
3.2 Progress in Chlorination Roasting
In fluidized bed reactors (650°C):
2LiAlSi2O6+CaCl2→2LiCl+CaAl2Si4O12
Performance metrics:
- Lithium conversion rate: 92.5±2.5%
- Energy consumption: 8.5 GJ/t Li₂CO₃
- HCl recovery rate: >85%
4. Advanced Purification Technologies
4.1 Hydrogenation-Thermal Decomposition Process
Phase equilibrium control:
Li2CO3(s)+CO2(g)+H2O(l)⇌2LiHCO3(aq)
Optimal operating window:
- Carbonation temperature: 20±1°C
- CO₂ partial pressure: 0.38 MPa
- Decomposition rate: 1.2 g/(L·min)
4.2 Advancements in Electrolysis
Anion exchange membrane (AEM) requirements:
- Area resistance: <2 Ω·cm²
- Swelling ratio: <15%
- Current efficiency: >90%
5. Cutting-Edge Recycling Technologies
5.1 Direct Regeneration Technology
Defect repair mechanisms in LiFePO₄:
- Optimal lithiation conditions:
∙ Li/TM=1.05
∙ Sintering temperature: 680-720°C
∙ Oxygen partial pressure: 10⁻⁵ atm - Capacity recovery rate: >98.5%
5.2 Selective Leaching
Eh-pH diagram analysis of H₂SO₄-H₂O₂ system reveals:
- Optimal potential range: 0.6-0.8 V vs. SHE
- Fe³⁺/Li⁺ separation coefficient: 1.2×10⁴
- Lithium leaching efficiency: 98.9±0.5%
6. Sustainability Assessment
Table 1. Environmental Footprint Comparison of Processes (unit: kg CO₂-eq/t Li₂CO₃)
| Process Stage | Brine Method | Ore Method | Recycling Method |
|---|---|---|---|
| Raw Material Prep. | 850 | 1200 | 150 |
| Energy Consumption | 950 | 2800 | 450 |
| Chemical Usage | 300 | 500 | 200 |
| Total | 2100 | 4500 | 800 |
Life cycle assessment (LCA) shows recycling reduces:
- Water consumption: 68±5%
- Carbon emissions: 72±3%
- Land disturbance: 90%
7. Future Challenges and Opportunities
- Novel Separation Materials:
- Development of MOFs with molecular recognition capabilities
- Design of Li⁺-specific ionic liquids
- Process Intensification:
- High-gravity reactors (β>300g)
- Plasma-assisted decomposition
- Digital Control:
- DFT-based process parameter optimization
- Real-time monitoring via digital twins
- High-End Applications:
- Ultra-high-purity Li₂CO₃ (>99.99%) for solid-state electrolytes
- Single-crystal cathode precursor synthesis
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