Lithium iron phosphate battery

The lithium iron phosphate battery (LiFePO₄ battery), also known as an LFP battery or lithium ferrophosphate battery, is a type of lithium-ion battery that uses lithium iron phosphate (LiFePO₄) as the cathode material and a graphitic carbon electrode with a metallic backing as the anode. Because of their low cost, high safety, low toxicity, long cycle life, and other advantages, LFP batteries are widely used in vehicles, utility-scale stationary storage, and backup power systems. As of September 2022, LFP batteries accounted for 31% of the EV battery market, with 68% of that share coming from Tesla and BYD.^[1]

In 2022, Chinese manufacturers dominated LFP battery production. As relevant patents began to expire and demand for more affordable EV batteries increased, LFP production was expected to continue growing and potentially surpass lithium nickel manganese cobalt oxide (NMC) batteries.^[2]

The specific energy of LFP batteries is lower than that of other common lithium-ion battery types, such as nickel manganese cobalt (NMC) and nickel cobalt aluminum (NCA). As of 2024, CATL claimed that its LFP battery had a cell-level specific energy of 205 watt-hours per kilogram (Wh/kg), while BYD's LFP battery had a specific energy of 150 Wh/kg.^[3] The best NMC batteries can exceed 300 Wh/kg. Panasonic's “2170” NCA batteries, used in Tesla's 2020 Model 3 mid-size sedan, have a specific energy of around 260 Wh/kg, which is about 70% of their theoretical chemical value. LFP batteries also operate at a lower voltage than many other lithium-ion battery types.

• Minimum discharge voltage: 2.0–2.8 V
• Working voltage: 3.0–3.3 V
• Maximum viable voltage: 2.5–3.47 V
• Maximum charging voltage: 3.60–3.65 V

Gravimetric energy density: 95–172 Wh/kg, or 340–620 kJ/kg. Newer versions announced between late 2023 and early 2024 improved energy density from 180 Wh/kg to 205 Wh/kg without increasing production costs.

Volumetric energy density: 227–396 Wh/L, or 820–1,430 kJ/L.

Cycle life ranges from about 2,500 to more than 9,000 cycles, depending on operating conditions.^[4] New-generation, high-energy-density versions may offer a longer charging cycle life, potentially reaching around 15,000 cycles.

LFP batteries are widely used in stationary energy storage systems because of their low cost, high safety, and long cycle life. In stationary applications, their lower energy density compared with other lithium-ion chemistries is generally less significant.^[5]

Iron and phosphate are abundant in the Earth’s crust. LFP batteries do not contain nickel or cobalt, which can be expensive and subject to supply constraints. The mining of cobalt has raised human rights and environmental concerns, while nickel extraction has also been associated with environmental issues.^[6]

A 2020 report published by the Department of Energy compared the costs of large-scale energy storage systems using LFP and NMC batteries.^[7] It found that the price per kWh of LFP batteries was about 6% lower than that of NMC batteries and projected that LFP cells would last around 67% longer, meaning they could complete more cycles. Because of differences in cell characteristics, some other components in an LFP storage system may cost slightly more, but the overall cost per kWh remains lower than that of NMC systems.^[8]

In 2020, the lowest reported price for LFP cells was $80/kWh, or 12.5 Wh/$, while the average price was $137/kWh. By 2023, the average price had fallen to $100/kWh.^[9] In early 2024, VDA-sized LFP cells were available for less than RMB 0.5/Wh, or about $70/kWh. Chinese automaker Leapmotor stated that it purchased LFP cells at RMB 0.4/Wh, or about $56/kWh, and expected the price to fall further to RMB 0.32/Wh, or about $44/kWh. By mid-2024, assembled LFP batteries were available to consumers in the United States for around $115/kWh.

LFP chemistry offers a considerably longer cycle life than many other lithium-ion chemistries. Under normal conditions, it can support more than 3,000 cycles, while under optimal conditions it may exceed 10,000 cycles. In comparison, NMC batteries typically support around 1,000 to 2,300 cycles, depending on operating conditions.^[10]

LFP cells also tend to lose capacity more slowly over time, giving them a longer calendar life than battery chemistries such as lithium cobalt oxide (LiCoO₂), lithium manganese oxide (LiMn₂O₄), and lithium-ion polymer batteries.^[11][12]

Because each LFP cell has a nominal output of 3.2 V, four cells can be connected in series to provide a nominal voltage of 12.8 V. This is close to the nominal voltage of a six-cell lead-acid battery. Combined with the strong safety characteristics of LFP batteries, this makes them a suitable potential replacement for lead-acid batteries in applications such as vehicles and solar energy systems.

The charging system must be adapted to avoid damaging the LFP cells through excessive charging voltage, temperature-based voltage compensation, equalisation charging, or continuous trickle charging. The cells should also be balanced before the battery pack is assembled. In addition, a protection system is required to prevent any cell from being discharged below 2.5 V, as this may cause severe and irreversible damage through the conversion of LiFePO₄ into FePO₄.^[13]

One important advantage of LiFePO₄ over other lithium-ion chemistries is its strong thermal and chemical stability, which helps improve battery safety.^[14][15] Compared with layered oxide cathode materials such as lithium cobalt oxide (LiCoO₂) and NMC, which may release oxygen when heated, LFP generally has a higher decomposition temperature.^[16][17]

LFP batteries also have strong safety characteristics. Under normal operating conditions, their chemical composition is less likely to combust when exposed to ambient air, making them less prone to fire and giving them good overall thermal and chemical stability. However, LFP batteries can still catch fire under extreme conditions, such as severe overcharging, very high temperatures, or major physical damage.

As of 2008, the energy density of a new LFP battery was about 14% lower than that of a new LiCoO₂ battery.^[18] Since the discharge rate depends on battery capacity, a higher output rate can be achieved by using a larger-capacity battery when low-current cells are used.

LFP batteries are commonly used in stationary energy storage systems because of their advantages in cost, safety, and cycle life. In 2025, they accounted for approximately 85% of the stationary storage market. In stationary applications, their lower energy density compared with other lithium-ion chemistries is generally less of a disadvantage.^[19]

LFP batteries are used in many electric vehicles because of their affordability, thermal stability, and durability.^[20] Some higher-end vehicles use NMC batteries because they provide greater energy density and performance. LFP batteries have gained a significant share of the electric vehicle battery market, particularly in China. Major electric vehicle manufacturers, including Tesla and BYD, have contributed significantly to their adoption.^[19]

• Chevrolet has used LFP batteries supplied by A123 Systems in the Spark EV.^[21]
• Renault uses an LFP battery in the electric version of the Twingo.^[22]
• Tesla uses LFP batteries in many of its standard-range vehicles, although some versions use NMC battery chemistry.^[23]

LFP batteries are also used in some electronic cigarettes, marine electrical and propulsion systems, flashlights, radio-controlled models, portable power equipment, amateur radio devices, industrial sensor systems, and emergency lighting.^[24]

LiFePO₄ is a natural mineral known as triphylite. Arumugam Manthiram and John B. Goodenough first identified the polyanion class of cathode materials for lithium-ion batteries.^[25][26][27] LiFePO₄ was later identified by Padhi and colleagues as a polyanion-based cathode material for battery applications. The reversible extraction of lithium from LiFePO₄ and its insertion into FePO₄ were also demonstrated. Because of its low cost, non-toxicity, abundant iron resources, excellent thermal stability, safety characteristics, electrochemical performance, and specific capacity of 170 mA·h/g, or 610 C/g, it has gained considerable market acceptance.^[28]

The main obstacle to commercialization was its naturally low electrical conductivity. This issue was addressed by reducing the particle size, coating LiFePO₄ particles with conductive materials such as carbon nanotubes, or combining both methods.^[29] Michel Armand and his coworkers at Hydro-Québec and the Université de Montréal developed this approach in 2015.^[30] Another method developed by Yet-Ming Chiang’s group at MIT involved doping LFP with cations of materials such as aluminium, niobium, and zirconium.

Negative electrodes, or anodes during discharge, made of petroleum coke were used in early lithium-ion batteries, while later types used natural or synthetic graphite.^[31]

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