Lithium iron phosphate (LiFePO₄) battery’s thermal stability is significantly greater than that of other lithium-ion batteries. Its thermal runaway onset temperature reaches as high as 800-1000°C (200-300°C for ternary lithium battery), and the surface temperature only reaches 150°C in the needle-puncture test (GB/T 31485 standard). And there is no open flame and explosion involved (CATL 2023 test data). Depending on UL 1642 certification result, in the final stage of overcharging up to 150% capacity, expansion ratio of LiFePO₄ battery is ≤5% (≥20% for ternary cells), and the volume of flammable gas produced by electrolyte decomposition decreases by 87% (e.g., CO content decreases from 500ppm to 65ppm).
Cycle life bears very close correlation with safety. Although after 3000 charge and discharge cycles, LiFePO₄ battery’s capacity retention rate can be ≥80% (60% for ternary battery) and the increase rate of internal resistance is only 0.5mΩ/100 times (compared to 1.2mΩ for ternary battery). Real vehicle tests on BYD’s Blade Battery show that in the case of continuous charging and discharging at a 2C rate in a 45℃ high-temperature environment, the temperature difference between the battery pack is controlled within ±2°C (±5°C for traditional batteries), and the energy consumption of the thermal management system is reduced by 40%. The Tesla Megapack energy storage system utilizes LiFePO₄ batterie, the lifespan of which is designed for up to 20 years (8,000 cycles) and an annual capacity loss factor of 0.5% (2% for ternary batterie).
Cost safety margin is significant. The raw material expense of LiFePO₄ batterie is 35% less than that of ternary batteries (60% less lithium carbonate used), and the cobalt usage is 0. Catl’s 2023 financial report indicates that the yield rate of its LiFePO₄ production line has risen to 98.5% (92% for ternary batteries), and the cost of production per GWh has fallen to 5 million yuan (7.5 million yuan for ternary batteries). Ubs research indicates that electric vehicles based on LiFePO₄ have a possibility of 0.004 per 10,000 units to be on fire (0.03 times when the ternary battery is used), and it is possible to reduce insurance costs by 18%.
The mechanical safety testing is stringent. When it passes the GB 38031-2020 extrusion test, LiFePO₄ batterie deforms merely 30% under 100kN pressure (ternary battery casing cracked), and the voltage drop is ≤10% (ternary battery ≥50%). The Norwegian Maritime Authority’s 2022 accident report describes that the ship using LiFePO₄ did not experience thermal diffusion in the battery compartment within 72 hours of the collision, while the ternary battery pack initiated the fire protection system within 24 hours.
In environmental safety, the toxic content concentration in LiFePO₄ batterie is 90% lower than in nickel-cobalt-manganese Batteries, and recycling percentage is 98% (70% according to EU Batteries Directive 2023). Hunan Bomp Recycling’s recycling process shows that the cost of regenerating LiFePO₄ cathode material is 40 yuan /kg (ternary material is 120 yuan), and the quantity of leached heavy metals complies with the EPA TCLP requirement (lead <5ppm, nickel <20ppm).
Completeness in regulation ensures safety. LiFePO₄ battery has passed UN38.3 air transport certification (vibration frequency test 7Hz-200Hz, acceleration 8G) and IEC 62619 industrial application certification (overcharge/overdischarge protection response time <50ms). NFPA 855 standard in the US allows energy density of LiFePO₄ energy storage system to be extended to 50kWh/m² (ternary battery limit is 20kWh), and no additional fire separation distance is required.
Remaining hazards must be addressed. Based on a 2023 study by Tsinghua University, the nominal capacity of LiFePO₄ batterie decreases to 65% (75% for ternary batteries) under a low-temperature condition of -30℃, and the growth rate of lithium dendrite during fast charging is three times higher than that at room temperature. Nevertheless, with a preheating system (with the energy demand reduced from 15% to 5%) and new additives to the electrolyte (such as 1% LiPO2F2), its low-temperature performance can be improved to 85% of nominal.