Lithium iron phosphate LiFePO battery, also known as LFP battery ("LFP" stands for "lithium iron phosphate"), is a rechargeable battery, especially a lithium-ion battery, which uses LiFePO as a graphite carbon electrode as the cathode material. The electrical grid serves as the anode. The specific capacity of LiFePO is higher than the related lithium cobalt oxide (LiCoO) chemical reaction, but its energy density is slightly lower due to its low operating voltage. The main problem with LiFePO is its low conductivity. Therefore, all the 4 cathodes that LiFePO is considering are actually LiFePO due to low cost, low toxicity, well-defined, long-term stability, etc. LiFePO is found in many roles in-vehicle use, utility-scale fixed applications, and backup power sources. History Lithium iron phosphate is a natural mineral of the olivine family (triterpene ore). It is used as a battery electrode, originally published by John B. Goodenough's research group at the University of Texas in 1996 as a cathode material for rechargeable lithium batteries. Due to its low cost, non-toxic, natural rich iron, excellent thermal stability, safety characteristics, electrochemical performance, and specific capacity (170 mA·h/g, or 610 C/g), it has achieved considerable Market recognition. [The main obstacle to commercialization is its inherently low conductivity. By reducing the particle size, coating LiFePO to overcome the problem of particles with conductive materials, such as carbon nanotubes, or both. The group by another method includes materials doped with LFP and cations, such as aluminum, niobium, and zirconium. The product is now mass-produced and used in industrial products by large companies, including the Black and Decker brand. The Massachusetts Institute of Technology has introduced a new type of coating that makes it easier for ions to move inside the battery. "Beltway Battery" uses a bypass system that allows lithium ions to enter and leave the electrodes at a speed large enough to fully charge the battery in one minute. Scientists have discovered that by coating lithium iron phosphate particles in a glass-like material called lithium pyrophosphate, ions bypass the channel and move faster than other batteries. When charged atoms (ions) move between two electrodes (anode and cathode), rechargeable batteries store and release energy. Their charging and discharging rates are limited by the speed at which these ions move. This technology can reduce the weight and size of the battery. A small prototype battery has been developed that can be fully charged in 10 to 20 seconds, compared to 6 minutes for a standard battery. In the early lithium-ion batteries, a negative electrode (anode, discharge) made of petroleum coke was used; later types used natural or synthetic graphite. [
pros and cons
The lithium iron phosphate 4 battery uses lithium-ion derivative chemicals and has many advantages and disadvantages with other lithium-ion battery chemicals. However, there are significant differences. Compared with other lithium-ion methods, LFP chemicals have a longer cycle life. [Like nickel-based rechargeable batteries (different from other lithium-ion batteries), LiFePO batteries have a very constant discharge voltage. During the discharge, the voltage remains close to 3.2 V until the battery is exhausted. This allows the battery to provide almost full power before it is discharged, and it can greatly simplify or even eliminate the need for voltage regulation circuits. Due to the rated 3.2 V output, four batteries can be placed in series with a nominal voltage of 12.8 V. This is close to the nominal voltage of a six-cell chloric acid battery. In addition to the good safety characteristics of LFP batteries, this makes LFP a good substitute for lead-acid batteries in automotive and solar applications, provided that the charging system does not damage the LFP batteries due to overcharging voltage (over 3.6). The battery voltage is DC, voltage compensation based on temperature, equalization attempt or continuous trickle charge. Before assembling the battery pack, the LFP battery must be at least balanced, and a protection system needs to be implemented to ensure that the battery will not be discharged or severely damaged in most cases under 2.5V. The use of phosphate avoids the cost and environmental problems of cobalt, especially the possibility of cobalt entering the environment through improper handling and the possibility of thermal runaway characteristics of cobalt-content rechargeable lithium batteries. Lithium iron phosphate has a higher current or peak power rating than LiCoO. The energy density (energy/volume) of the new LFP battery is about 14% lower than that of the new LiCoO battery. In addition, many brands of LFP, as well as the batteries in a given brand of LFP battery, have a lower discharge rate than lead-acid or LiCoO. Since the discharge rate is a percentage of the battery capacity, if a low-current battery must be used, use a larger battery (More ampere-hours) Higher rates can be achieved. Even better, high-current LFP batteries (which have a higher discharge rate than lead-acid or LiCoO) can use batteries of the same capacity). Compared with lithium-ion battery chemicals (such as LiCoO), lithium iron phosphate has a slower capacity loss rate (ie longer calendar life). Cobalt or LiMn manganese spinel lithium-ion polymer battery (LiPo battery) or lithium-ion battery. After being placed on the shelf for one year, a LiFePO battery usually has approximately the same energy density as LiCoO. 2 Lithium-ion batteries, because the energy density of LFP decreases slowly. Compared with other lithium chemicals, LFP undergoes slower degradation when stored in a fully charged state. This makes LFP an ideal choice for standby use. An important advantage of safety compared with other lithium-ion chemicals is thermal and chemical stability, which improves the safety of the battery. LiFePO is an intrinsically safer cathode material and manganese spinel than LiCoO. By omitting cobalt, its negative resistance, and increased thermal performance potentially promote thermal runaway. The iron P-bond is stronger than the iron, so that when abused, (short circuit, overheating, etc.) the oxygen atoms are more difficult to remove. This stabilization of redox energy also contributes to rapid ion migration. As lithium migrates out of the cathode cell in LiCoO, CoO undergoes nonlinear expansion, which affects the structural integrity of the cell. The structure of LiFePO in the full lithiation and non-lithiation state is similar, indicating that LiFePO batteries are structurally more stable than LiCoO cells. In the fully charged LiFePO cathode, there are no lithium residual units in the LiCoO battery, and approximately 50% remains in the cathode. The oxygen in lithium iron phosphate has high elasticity during oxygen loss, which usually leads to exothermic reactions in other lithium batteries. Therefore, lithium iron phosphate batteries are more difficult to ignite during misoperation (especially during charging), although any fully charged battery can only dissipate overcharge energy as heat. Therefore, it is still possible to cause battery failure through misuse. It is generally believed that LiFePO batteries will not decompose at high temperatures. The difference between LFP and LiPo batteries commonly used in model aircraft hobbies is particularly noteworthy. Specifications Battery voltage Minimum discharge voltage = 2.5 V Working voltage = 3.0~3.3 V. Maximum charging voltage = 3.65 V. Volume energy density = 220 Wh / dm (790 kJ / dm 3) Weight energy density> 90 Wh / kg (> 320 J/g) 100% DOD cycle life (the number of cycles reaches 80% of the original capacity) = 2,000-7,000 10% DOD cycle life (the number of cycles reaches 80% of the original capacity)> 10,000 [Sony Fortelion: owns 100% of the Department of Defense After 8,000 cycles, the capacity is 74% cathode composition (weight) 90% C-LiFePO 4, grade Phos-Dev-125% carbon EBN-10-10 (high quality graphite) 5% polyvinylidene fluoride (PVDF) unit configuration carbon Coated aluminum current collector 151.54cm Catholyte: Ethylene carbonate-dimethyl carbonate (EC-DMC) 1-1 Lithium perchlorate (LiClO1M anode: graphite or hard carbon, insert metal lithium Experimental conditions: indoor temperature and voltage limits : 2.0-3.65 V. Charging: up to C / 1 rate up to 3.6 V, then constant voltage 3.6 V, until I <C / 24. According to the manufacturer BYD, the lithium iron phosphate battery of the electric car e6 is at a fast-charging station at 15 Charge to 80% in minutes and 100% in 40 minutes. [Usage The higher discharge rate required for traffic acceleration, lighter weight and longer service life make this battery type ideal for bicycles and electric vehicles The 12V LiFePO 4 battery is also becoming more and more popular as the second (house) battery for caravans, car homes or boats.
Solar garden and security lighting system
A single "14500" (AA battery size) LFP battery is now used in some solar path lights instead of 1.2 V NiCd/NiMH. The higher (3.2 V) operating voltage of the LFP allows a single unit to drive the LED without the need for a boost circuit. The increased tolerance to overcharge (compared to other Li-battery types) means that LiFePO can be connected to photovoltaic cells without complicated circuits. A single LFP battery can also alleviate the corrosion, condensation, and fouling problems associated with the battery holder and battery-to-battery contact-this poor connection is often particularly troublesome for outdoor systems that use multiple removable NiMH batteries. More complex LFP solar charging passive infrared safety lights are also emerging (2013). Since the capacity of the AA size LFP battery is only 600 mA·h (and the bright LED of the light may consume 60 mA), it is estimated that only 10 hours of running time will be required. However-if triggered only occasionally-this system can even cope under low-sunlight charging conditions, because the light electronics ensure that after a dark "idle" current of less than 1mA. Lithium iron phosphate power solar lights are significantly brighter than ordinary outdoor solar lights, and the overall performance is considered more reliable.
Other uses
Many home-use EV conversions use large-format versions as towing packages for cars. With an efficient power-to-weight ratio, high safety, and chemical resistance to thermal runaway, amateur home "manufacturers" have almost no obstacles. Motorhomes are usually converted into lithium iron phosphate due to high extraction.
