Lithium iron phosphate battery
The lithium iron phosphate battery or LFP battery is a type of lithium-ion battery using lithium iron phosphate 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 factors, LFP batteries are finding a number of roles in vehicle use, utility-scale stationary applications, and backup power. LFP batteries are cobalt-free. As of September 2022, LFP type battery market share for EVs reached 31%, and of that, 68% were from EV makers Tesla and BYD alone.
In 2022, Chinese manufacturers held a near-monopoly of LFP battery type production. With patents having started to expire in 2022 and the increased demand for cheaper EV batteries, LFP type production is expected to rise further and surpass lithium nickel manganese cobalt oxides type batteries.
The specific energy of LFP batteries is lower than that of other common lithium-ion battery types such as nickel manganese cobalt and nickel cobalt aluminum. As of 2024, the specific energy of CATL's LFP battery is claimed to be 205 watt-hours per kilogram on the cell level. BYD's LFP battery specific energy is 150 Wh/kg. The best NMC batteries exhibit specific energy values of over 300 Wh/kg. Notably, the specific energy of Panasonic's "2170" NCA batteries used in Tesla's 2020 Model 3 mid-size sedan is around 260 Wh/kg, which is 70% of its "pure chemicals" value. LFP batteries also have a lower operating voltage than other lithium-ion battery types.
Specifications
- Cell voltage
- * Minimum discharge voltage = 2.0-2.8 V
- * Working voltage =
- * Max viable voltage =
- * Maximum charge voltage = 3.60-3.65 V
- Volumetric energy density = 220 Wh/L
- Gravimetric energy density > 90 Wh/kg. Up to 160 Wh/kg. The latest version announced at the end of 2023, early 2024 made significant improvements in energy density from 180 up to 205 Wh/kg without increasing production costs.
- Cycle life from 2,500 to more than 9,000 cycles depending on conditions. Next generation high-energy density versions have increased charging lifecycles, probably around 15,000 maximum cycles.
Comparison with other battery types
Resource availability
Iron and phosphates are very common in the Earth's crust. LFP contains neither nickel nor cobalt, both of which are supply-constrained and expensive. As with lithium, human rights and environmental concerns have been raised concerning the use of cobalt. Environmental concerns have also been raised regarding the extraction of nickel.Cost
A 2020 report published by the Department of Energy compared the costs of large-scale energy storage systems built with LFP vs NMC. It found that the price per kWh of LFP batteries was about 6% lower than that of NMC batteries, and it projected that LFP cells would last about 67% longer. Because of differences between the cell's characteristics, the cost of some other components of the storage system would be somewhat higher for LFP, but on balance it remains less costly per kWh than NMC.In 2020, the lowest reported LFP cell prices were $80/kWh with an average price of $137/kWh, while in 2023 the average price had dropped to $100/kWh.
By early 2024, VDA-sized LFP cells were available for less than RMB 0.5/Wh, while Chinese automaker Leapmotor stated it buys LFP cells at RMB 0.4/Wh and believe they could drop to RMB 0.32/Wh. By mid 2024, assembled LFP batteries were available to consumers in the US for around $115/kWh.
Better aging and cycle-life characteristics
LFP chemistry offers a considerably longer cycle life than other lithium-ion chemistries. Under most conditions, it supports more than 3,000 cycles; under optimal conditions, more than 10,000 cycles. NMC batteries support about 1,000 to 2,300 cycles, depending on conditions.LFP cells experience a slower rate of capacity loss than lithium-ion battery chemistries such as cobalt, manganese spinel, lithium-ion polymer batteries or lithium-ion batteries.
Viable alternative to lead-acid batteries
Because of the nominal 3.2 V output, four cells can be connected in series for a nominal 12.8 V. This comes close to the nominal voltage of a six-cell lead-acid batteries. Along with the good safety characteristics of LFP batteries, this makes LFP a good potential replacement for lead-acid batteries in applications such as automotive and solar applications, provided the charging systems are adapted not to damage the LFP cells through excessive charging voltages, temperature-based voltage compensation, equalisation attempts or continuous trickle charging. The LFP cells must be at least balanced initially before the pack is assembled and a protection system also needs to be implemented to ensure no cell can be discharged below a voltage of 2.5 V or severe damage will occur in most instances, due to irreversible deintercalation of LiFePO4 into FePO4.Safety
One important advantage over other lithium-ion chemistries is thermal and chemical stability, which improves battery safety. is an intrinsically safer cathode material than and manganese dioxide spinels through omission of the cobalt, whose negative temperature coefficient of resistance can encourage thermal runaway. The P–O bond in the Phosphate| ion is stronger than the Co–O bond in the ion, so that when abused, the oxygen atoms are released more slowly. This stabilization of the redox energies also promotes faster ion migration.As lithium migrates out of the cathode in a cell, the undergoes non-linear expansion that affects the structural integrity of the cell. The fully lithiated and unlithiated states of are structurally similar which means that cells are more structurally stable than cells.
No lithium remains in the cathode of a fully charged LFP cell. In a cell, approximately 50% remains. is highly resilient during oxygen loss, which typically results in an exothermic reaction in other lithium cells. As a result, cells are harder to ignite in the event of mishandling. The battery does not decompose at high temperatures.
Lower energy density
The energy density of a new LFP battery as of 2008 was about 14% lower than that of a new battery. Since discharge rate is a percentage of battery capacity, a higher rate can be achieved by using a larger battery if low-current batteries must be used.Uses
Home energy storage
pioneered LFP along with SunFusion Energy Systems LiFePO4 Ultra-Safe ECHO 2.0 and Guardian E2.0 home or business energy storage batteries for reasons of cost and fire safety, although the market remains split among competing chemistries. Though lower energy density compared to other lithium chemistries adds mass and volume, both may be more tolerable in a static application. In 2021, there were several suppliers to the home end user market, including SonnenBatterie and Enphase. Tesla Motors continued to use NMC batteries in its home energy storage products until the release of the Tesla Powerwall 3 in 2023. Tesla utility-scale batteries switched to using LFP in 2021. According to EnergySage the most frequently quoted home energy storage battery brand in the U.S. is Enphase, which in 2021 surpassed Tesla Motors and LG.Vehicles
Higher discharge rates needed for acceleration, lower weight and longer life make this battery type ideal for forklifts, bicycles, and electric cars. Twelve-volt LiFePO4 batteries are also gaining popularity as a second battery for a caravan, motor-home or boat.Tesla Motors uses LFP batteries in all standard-range Models 3 and Y made after October 2021 except for standard-range vehicles made with 4680 cells starting in 2022, which use an NMC chemistry.
As of September 2022, LFP batteries had increased their market share of the entire EV battery market to 31%. Of those, 68% were deployed by two companies, Tesla and BYD.
Lithium-iron phosphate batteries officially surpassed ternary batteries in 2021, accounting for 52% of installed capacity. Analysts estimate that its market share will exceed 60% in 2024.
The first vehicle to use LFP batteries was the Chevrolet Spark EV in 2014. A123 Systems made the batteries. In February 2023, Ford announced it would invest $3.5 billion to build a factory in Michigan to produce low-cost batteries for some of its electric vehicles. The project will be wholly owned by a Ford subsidiary, but will use technology licensed from Chinese battery company Contemporary Amperex Technology Co., Limited.
Solar-powered lighting systems
Lithium iron phosphate batteries, known for their stable operating voltage and high safety, have been widely used in solar lighting systems. Compared to traditional nickel-cadmium or nickel-metal hydride batteries, LiFePO4 batteries offer a longer cycle life and superior thermal stability, making them well-suited for solar applications that require frequent charging and discharging.In addition, LiFePO4 batteries exhibit a high tolerance to overcharging during the charging process, allowing them to be connected directly to solar panels without the need for complex charge control circuitry. This makes them an ideal energy source for solar garden lights, streetlights, and other outdoor lighting systems.
By 2013, better solar-charged passive infrared motion detector security lamps emerged. As AA-sized LFP cells have a capacity of only 600 mAh, the units shine for at most 10 hours. However, if triggering is only occasional, such units may be satisfactory even charging in low sunlight, as lamp electronics ensure after-dark "idle" currents of under 1 mA.