lithium iron phosphate ( LiFePO
4 ) battery , also called LFP battery (with "LFP" for "lithium ferrophosphate"), is a type of rechargeable battery, especially lithium-ion batteries, span> LiFePO
4 as a cathode material, and graphite carbon electrodes with a metal current collector grid as anode. Specific Capacity LiFePO
4 higher rather than the corresponding lithium cobalt oxide ( LiCoO
2 ) chemistry, but its energy density is slightly lower due to low operating voltage. Main problem LiFePO
4 low electrical conductivity. Therefore, all LiFePO
4 cathodes under consideration LiFePO
4 /C. Due to low cost, low toxicity, well-defined performance, long-term stability, etc. LiFePO
4 is finding a number of roles in vehicle usage and backup power.
Video Lithium iron phosphate battery
History
LiFePO
4 is a natural mineral of the olivine family (triphylite). Its use as a battery electrode was first described in the literature published by research group John B. Goodenough at the University of Texas in 1996, as a cathode material for rechargeable lithium batteries. Because of its low cost, non-toxicity, natural iron abundance, excellent thermal stability, safety characteristics, electrochemical performance, and specific capacity (170 mA Â · h/g, or 610 C/g) it gained some market acceptance.
The main obstacle to commercialization is its intrinsically low electrical conductivity. This problem is solved by reducing the particle size, coating LiFePO
4 particles with conductive materials such as carbon nanotubes, or both. This approach was developed by Michel Armand and his co-workers. Another approach by the Ming Ming group however consists of LFP doping with cation materials such as aluminum, niobium, and zirconium. The products are now in mass production and are used in industrial products by major companies including DeWalt Black and Decker brands, Fisker Karma, Daimler AG, Cessna and BAE Systems.
MIT introduced a new coating that allows the ion to move more easily inside the battery. "Beltway Battery" uses a bypass system that allows lithium ions to enter and leave the electrode at a speed large enough to fully charge the battery in less than a minute. The scientists discovered that by coating the lithium iron phosphate particles in a glass material called lithium pyrophosphate, the ions cut channels and move faster than in other batteries. Rechargeable batteries store and release energy when the charged atom (ion) is transferred between two electrodes, anode and cathode. Their fill and discharge rate is limited by the speed at which these ions move. Such technology can reduce the weight and size of the battery. A small prototype battery cell has been developed that can be fully charged in 10 to 20 seconds, compared to six minutes for a standard battery cell.
The negative electrode (anode, at discharge) made from petroleum coke is used in early lithium-ion batteries; the next type using natural or synthetic graphite.
Maps Lithium iron phosphate battery
Advantages and disadvantages
The LiFePO
4 lithium-ion is derived and shares many advantages and disadvantages with other lithium-ion battery chemistries. However, there is a significant difference.
LFP chemistry offers a longer life cycle than any other lithium-ion approach.
Like nickel based rechargeable batteries (and unlike other lithium ion batteries), LiFePO
4 Battery has a very constant discharge voltage. The voltage remains close to 3.2 V during discharge until the cell is discharged. This allows the cells to transmit full power up, and it can greatly simplify or even eliminate the need for voltage regulation circuits.
Because of the nominal 3.2 V output, four cells can be placed in series for a nominal voltage of 12.8 V. This is close to the nominal six-cell battery lead acid voltage. And, together with the good safety characteristics of LFP batteries, this makes LFP a good potential replacement for acid-lead batteries in many applications such as automotive and solar applications, provided the charging system is adjusted so as not to damage LFP cells through excessive charge voltage. (surpassing 3.6 volts DC per cell when below cost), temperature-based voltage compensation, equity effort or continuous drip filling. The LFP cell should be at least balanced initially before the pack is assembled and the protection system also needs to be implemented to ensure no cells can be discharged below 2.5 V voltage or severe damage will occur in most cases.
The use of phosphate avoids the cost of cobalt and environmental problems, especially concerns about cobalt entering the environment through improper discharges, as well as the potential for runaway thermal characteristics of refillable cobalt refillable lithium cells to manifest itself.
LiFePO
4 higher or higher power rating of LiCoO
2 .
The energy density (energy/volume) of the new LFP battery is about 14% lower than the battery LiCoO
2 battery. Also, many brands of LFP, as well as cells in a given brand of LFP battery, have a lower discharge rate than lead acid or LiCoO
2 . Since the discharge rate is the percentage of battery capacity, a higher level can be achieved by using larger batteries (more ampere hours) if a low current battery should be used. Better yet, the LFP cell is currently high (which will have higher discharge rate than lead acid or LiCoO
2 battery of the same capacity) can be used.
LiFePO
4 cell decreases slower capacity (aka larger calendar life) than lithium-ion battery chemistry such as LiCoO
2 cobalt or LiMn
2 O
4 spinel manganese lithium-ion polymer battery (LiPo battery) or lithium-ion battery. After one year on the shelf, LiFePO
4 cells usually have an energy density similar to LiCoO
2 Li-ion cells, due to a slower decline in LFP energy density. Security
One of the important advantages over other lithium-ion chemicals is thermal and chemical stability, which increases battery security. LiFePO
4 is intrinsic material cathode is safer than LiCoO
2
When lithium migrates out of the cathode in LiCoO
2 cell, CoO
2 experience non-linear expansion that affects the structural integrity of the cell. Circumstances litsiated and unlithiated LiFePO
4 structurally similar which means that LiFePO
4 cells are more structurally stable than LiCoO
2 cell.
No lithium is left in the cathode of LiFePO
4 cell - in LiCoO
2 cells, about 50% remain in the cathode. LiFePO
4 oxygen, which usually produces exothermic reactions in other lithium cells.
As a result, lithium iron phosphate cells are much more difficult to light up in case of faulty handling (especially during charging) even if a fully charged battery can only dispose of the overcharge energy as heat. Therefore, battery failure through misuse is still possible. It's commonly accepted that LiFePO
4 batteries do not decompose at high temperatures. The difference between LFP and LiPo battery cells commonly used in aeromodelling hobby is very important.
Specifications
- Cell voltage
- Minimum voltage discharge = 2.5Ã, V
- Working voltage = 3.0 ~ 3.3 V
- Maximum charging voltage = 3.65 V
- Volumetric energy density = 220Ã, Wh/dm 3 (790 kJ/dm 3 )
- Gravimetry energy density & gt; 90A Wh/kg (& gt; 320 J/g)
- 100% DOD life cycle (number of cycles up to 80% of original capacity) = 2,000-7.000
- 10% DOD life cycle (number of cycles up to 80% of original capacity) & gt; 10,000
- Sony Fortelion: 74% capacity after 8,000 cycles with 100% DOD
- The composition of the cathode (heavy)
- 90% C-LiFePO 4 , class Phos-Dev-12
- 5% carbon EBN-10-10 (superior graphite)
- 5% polyvinylidene fluoride (PVDF)
- Configure cells
- Aluminum-coated aluminum current collector 15 catheter
- 1.54 cm 2
- Electrolyte: ethylene carbonate-dimethyl carbonate (EC-DMC) 1-1 lithium perchlorate ( LiClO
4 ) 1M - Anode: graphite or hard carbon with intercalated metallic lithium
- Experimental conditions:
- Room temperature
- Voltage limits: 2.0-3.65 V
- Charge: Up to C/1 rate up to 3.6Ã, V, then constant voltage at 3.6Ã, V to I & lt; C/24
- According to BYD manufacturers, lithium iron phosphate batteries from electric cars e6 are charged to fast charging stations up to 80% within 15 minutes, and 100% in 40 minutes.
Usage
Transportation
A higher discharge rate is required for acceleration, lower body weight and longer life makes this type of battery ideal for bicycles and electric cars.
Solar garden and security light system
The single "14500" LFP cell (AA battery) is now used in some solar powered street lights instead of 1,2Ã,V NiCd/NiMH.
LFP's higher work voltage (3.2 V) can allow a single cell to drive the LED without the need for a step-up circuit. Increased tolerance of low overcharging (compared to other Li cell types) means that LiFePO
4 can connect to photovoltaic cells without complex circuits. One LFP cell also alleviates the problem of corrosion, condensation and impurities associated with battery holder and cell-to-cell contact - such poor connections often primarily disrupt outdoor systems that use some removable NiMH cells.
More sophisticated passive infrared light illumination from LFP also appears (2013). [1] Since AF-sized LFP cells have a capacity of only 600 mA? H (while bright LED light can pull 60 mA) only 10 hours operation time can be expected. However - if the trigger is only occasional - the system can cope even in low sunlight conditions, such as electronic lights ensuring after dark "idle" currents below 1 mA.
LiFePO
4 looks brighter than outdoor solar lights everywhere, and overall performance is considered more reliable.
Other uses
Many EV home conversions use large format versions as a car traction package. With an efficient power-to-weight ratio, high safety features and chemical rejection to go to the thermal runaway, there are some obstacles to being used by amateur home "makers".
Some electronic cigarettes use this type of battery.
Three manufacturers of torches/flashlights (Imecs Corporation with wireless LiFePO
4 Battery Technology, Mag Instrument and LED Lenser) have a product that utilizes this battery.
RC model cars can use these batteries, especially as RX and TX packets as a direct replacement of NiMh or LiPo packets without the need for voltage regulators, as they provide 6.6 V nominal voltage over 7.4 V LiPo packets, which are slightly higher and may need set to 6.0Ã, V.
Celestron has come out with a light "PowerTank Lithium" battery that uses this chemical to power their telescope drive. It weighs only 2.25 pounds (1.02 kg) and produces 84.6 W? H and 12 V DC. In addition, internal batteries in some of their telescope mounts use this chemical.
See also
References
Source of the article : Wikipedia
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