На сегодняшний день существует большое количество batteries with different types of chemistry. The most popular batteries today are lithium-ion. This group also includes lithium-iron-phosphate (ferrophosphate) batteries. If all the batteries in this category are, by and large, similar to each other in technical characteristics, then lithium-iron-phosphate batteries have their own unique features, distinguishing them from other batteries made by lithium-ion technology.
History of the discovery of lithium-iron-phosphate battery
The inventor of the LiFePO4 battery is JohnGudenaf, who worked in 1996 at the University of Texas to create a new material for the cathode for lithium-ion batteries. The professor managed to create a material with greater cheapness, with less toxicity and high thermal stability. Among the shortcomings of the battery in which the new cathode was used was a smaller capacity.
The invention of john gudenaf no onewas interested, but in 2003, A 123 Systems decided to develop this technology, considering it to be quite promising. Investors of this technology have become many large corporations - Sequoia Capital, Qualcomm, Motorola.
Characteristics of LiFePO4 batteries
The voltage of the ferrophosphate battery is the sameas with other batteries related to lithium-ion technology. The nominal voltage depends on the size of the battery (size, form factor). For 18,650 batteries, this is 3.7 volts, for 10,440 (little finger) - 3.2, for 24,330 - 3.6.
Almost all batteries have a voltage ofthe process of discharge gradually falls. One of the unique features is voltage stability when operating on LiFePO4 batteries. Voltage characteristics similar to these have batteries made by nickel technology (nickel-cadmium, nickel-metal hydride).
Full discharge voltage is 2.0 volts,which is the lowest registered discharge limit among all batteries on lithium technology. These batteries are the leaders and in service life, which is equivalent to 2000 cycles for charge and discharge. Due to the safety of its chemical structure, LiFePO4 batteries can be charged using the special accelerated delta V method when a large current is applied to the battery.
Many batteries do not withstand charging bysuch a method that leads to their excessive heating and damage. In the case of lithium-iron-phosphate batteries, using such a method is not just possible, but even recommended. Therefore, specially for charging such batteries, there are special chargers. Of course, such chargers can not be used on batteries with a different chemistry. Depending on the form factor, lithium-iron-phosphate batteries on such chargers can be fully charged in 15-30 minutes.
Recent developments in the fieldLiFePO4 batteries offer the user batteries with an improved operating temperature range. If the standard range for lithium-ion batteries is from -20 to +20 degrees Celsius, then lithium-iron-phosphate batteries can work perfectly in the range from -30 to +55. Charging or discharging the battery at temperatures higher or lower than described will severely damage the battery.
Lithium iron phosphate batteries are subject tothe aging effect is much less than other lithium-ion batteries. Aging is a natural loss of capacity over time, which does not depend on whether the battery is used or lying on the shelf. For comparison: all lithium-ion batteries lose about 10% of capacity each year. Lithium-iron-phosphate lose only 1.5%.
Of the drawbacks of these batteries is to allocate a smaller capacity, which is 14% less (or so) than other lithium-ion batteries.
Safety of ferrophosphate batteries
This type of battery is considered one ofthe safest among all existing types of batteries. Lithium phosphate batteries LiFePO4 have very stable chemistry, and are able to withstand heavy loads when discharged (in low resistance) and charge (when charging the battery with large currents).
Due to the fact that phosphates are chemically safe,These batteries are easier to dispose of after they have expired. Many hazardous chemicals batteries (for example, lithium-cobalt) have to undergo additional recycling processes in order to negate their environmental hazards.
Charging lithium iron phosphate batteries
One of the reasons for the commercial interest of investorsto ferrophosphate chemistry became the ability to fast charge, resulting from its stability. Immediately after the organization of the conveyor release of LiFePO4 batteries, they were positioned as batteries that can be quickly charged.
For this purpose, specialcharging device. As it was already written above, such chargers cannot be used on other batteries, as this will cause them to overheat and will spoil them greatly.
Special data chargerbatteries can charge them for 12-15 minutes. Ferrophosphate batteries can be charged with conventional chargers. There are also combined options for charging devices with both charging modes. The best option, of course, would be to use smart chargers with many options that regulate the charging process.
Lithium-iron phosphate battery device
No features in the internal deviceLiFePO4 lithium-iron-phosphate battery does not have a battery as compared to its counterparts in chemical technology. Only one element underwent a change - a cathode made of iron phosphate. The anode material is lithium (all batteries on lithium-ion technology have a lithium anode).
The operation of any battery is based onreversibility of a chemical reaction. Otherwise, the processes occurring inside the battery are called oxidation and reduction processes. Any battery consists of electrodes - the cathode (minus) and the anode (plus). Also inside any battery there is a separator - a porous material impregnated with a special liquid - electrolyte.
When the battery is discharged, lithium ions movethrough the separator from the cathode to the anode, giving the accumulated charge (oxidation). When charging the battery, lithium ions move in the opposite direction from the anode to the cathode, accumulating charge (recovery).
Types of lithium-iron phosphate batteries
All types of batteries in this chemistry can be divided into four categories:
- Full battery.
- Large cells in the form of parallelepipeds.
- Small cells in the form of parallelepipeds (prismatic - LiFePO4 batteries of 3.2 V).
- Small flat batteries (packs).
- Cylindrical batteries.
Lithium-iron-phosphate batteries and cells may havedifferent nominal voltage from 12 to 60 volts. In many ways, they are ahead of the traditional lead-acid batteries: the cycle of work is much higher, the weight is several times lower, and it is recharged several times faster.
Cylindrical batteries in this chemistry are used both separately and in the chain. Dimensions of these cylindrical batteries are very different: from 14,500 (finger) to 32,650.
Lithium iron phosphate battery
Отдельного внимания достойны феррофосфатные АКБ for bicycles and electrocycles. With the invention of the new iron-phosphate cathode, along with other types of batteries, special batteries came out of this chemistry, which, due to their improved characteristics and lower weight, can be conveniently used even on ordinary bicycles. Similar batteries immediately gained popularity among fans of upgrading their bikes.
The use of ferrophosphate batteries
The role of the battery on this chemistry is clear and withoutcomments. Prismatic devices are used for different purposes - LiFePO4 3.2 v batteries. Larger cells are used as elements of buffer systems for solar energy and wind turbines. Ferrophosphate batteries are widely used in the design of electric vehicles.
Small flat batteries are used forphones, laptops and tablets. Cylindrical batteries of different form factors are used for airsoft weapons, electronic cigarettes, radio-controlled models, etc.
