Lithium iron phosphate
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Product Description
Lithium iron phosphate (LiFePO₄, LFP), discovered in 1997 by John B. Goodenough, is an olivine-structured cathode material that delivers exceptional safety (thermal runaway >500 °C), >3 000 deep cycles and low cost because it uses abundant Fe/P instead of Co/Ni; its drawbacks are lower energy density and poor sub-zero kinetics. Continuous nano-sizing, carbon coating and pack-level innovations such as BYD’s “blade” cell have pushed EV ranges past 600 km and enabled ≤10-min fast-charge, while new “high-compaction” generations (≥2.6 g cm⁻³) further raise volumetric capacity without sacrificing cycle life. These advances have made LFP the dominant chemistry in Chinese EVs, Tesla’s standard-range models and gigawatt-hour grid storage, and ongoing research on manganese-rich derivatives, solid-state electrolytes and closed-loop recycling is expected to widen its lead in sustainable, long-life batteries.
Other Information
Recycling:
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Necessity: With the first wave of LFP batteries reaching end-of-life, efficient recycling is crucial for environmental protection and resource sustainability (recovering Li, Fe, P).
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Methods:
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Direct Repair/Regeneration: Re-lithiation and purification of spent LFP cathode material for reuse.
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Hydrometallurgical Recovery: Leaching with acids followed by separation and precipitation to recover lithium (e.g., as Li₃PO₄ or Li₂CO₃) and iron.
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Emerging Green Methods: Electrochemical recovery is a promising, reagent-efficient method that can selectively leach Li⁺ from spent LFP powder with high efficiency (>99%) and minimal iron dissolution.
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Challenges: The lower economic value of recovered materials (vs. Co/Ni) requires cost-effective, low-energy recycling processes to be viable.
Synthesis and Production
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Primary Synthesis Methods:
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High-Temperature Solid-State Method: Traditional method involving solid-state reactions at high temperatures.
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Hydrothermal/Solvothermal Method: Uses aqueous or organic solvents under high temperature and pressure to produce fine, crystalline particles.
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Carbothermal Reduction Method: Uses carbon as a reducing agent to control oxidation states and often incorporates conductive carbon coating during synthesis.
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Co-precipitation Method: Involves the simultaneous precipitation of lithium, iron, and phosphate precursors to achieve homogeneous mixing.
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Sol-Gel Method: Forms a gel from molecular precursors, resulting in materials with high purity and homogeneity.
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Spray Pyrolysis/Microwave Methods: Emerging techniques aimed at faster, more energy-efficient production with controlled particle morphology.
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Industrial Focus: The goal is to develop low-cost, efficient, green, and scalable synthesis routes. Recent advancements aim to directly produce nano-sized and carbon-coated particles to enhance electrochemical performance.
Uses and Applications
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Electric Vehicles (EVs): A dominant application, especially for mid-range, cost-sensitive, and safety-critical models (e.g., Tesla Model 3/Y Standard Range, BYD Blade Battery vehicles, buses, logistics vehicles).
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Energy Storage Systems (ESS): The fastest-growing market due to its long life and safety.
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Grid-scale energy storage
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Home/Commercial energy storage
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Telecom base station backup power
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Consumer & Light Mobility:
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Electric bicycles, scooters, and tricycles (replacing lead-acid batteries).
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Power tools.
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Other Fields: Marine vessels, engineering machinery, and other specialty vehicles.
Chemical and Physical Properties
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Chemical & Structural:
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Formula: FeLiO₄P (PubChem CID: 15320824)
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CAS Number: 15365-14-7
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Structure: Olivine-type crystal structure (orthorhombic, Pnma space group).
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Molecular Weight: 157.8 g/mol
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Electrochemical Performance:
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Theoretical Capacity: ~170 mAh/g
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Operating Voltage: ~3.2-3.3 V (vs. Li⁺/Li)
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Cycling Life: Exceptionally long, typically 3,000 - 6,000+ cycles.
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Rate Capability: Good, especially for nano-sized, carbon-coated materials. Fast-charging behavior is linked to a non-equilibrium solid-solution mechanism at high currents.
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Energy Density: Lower than NMC/NCA ternary batteries. This is its primary drawback.
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Volumetric Energy Density: ~220 Wh/L
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Gravimetric Energy Density: ~160 Wh/kg
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Intrinsic Material Properties:
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Advantages:
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Excellent Safety & Thermal Stability: The olivine structure is very stable, with a high thermal runaway onset temperature (~500°C). It does not release oxygen upon decomposition.
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Low Cost: Raw materials (Fe, P) are abundant and inexpensive, with no reliance on costly Co or Ni.
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Environmental Friendliness: Non-toxic and has a lower environmental impact.
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Disadvantages/Challenges:
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Low Electronic Conductivity: ~10⁻⁹–10⁻¹⁰ S/cm.
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Low Lithium-Ion Diffusion Coefficient: ~10⁻¹⁴–10⁻¹⁶ cm²/s.
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Poor Low-Temperature Performance: Conductivity drops significantly below 0°C.
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Low Tap Density: Can lead to lower volumetric energy density in electrodes.
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Modification Strategies to Improve Performance:
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Nanocrystallization: Reducing particle size to shorten Li⁺ diffusion paths.
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Carbon Coating: Creating a conductive network on particle surfaces to boost electronic conductivity.
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Lattice Doping: Substituting Fe sites with ions like Mn (creating LMFP), Mg, Zn, etc., to enhance intrinsic conductivity and voltage plateau.
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Morphology Control: Synthesizing particles with specific shapes (e.g., platelets, rods) to optimize packing density and ion transport.
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Safety and Handling
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Regulatory Status (from PubChem):
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GHS Classification: According to ECHA data aggregated from 107 reports, 97.2% (104 reports) indicate the substance "does not meet GHS hazard criteria." It is generally reported as "Not Classified."
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Primary Hazards: Listed as "Not Classified" in the PubChem record.
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Intrinsic Safety (from Literature): LFP's primary advantage is its exceptional safety compared to other lithium-ion chemistries. Its stable structure makes it highly resistant to thermal runaway, fire, and explosion under abuse conditions (overcharge, short circuit, crush).
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Handling: Standard safe handling practices for industrial chemicals and battery materials should be followed, but it is not classified as a major hazard based on available data.