Basic Introduction And Working Principle Of Lithium Iron Phosphate Battery
The full name of the lithium iron phosphate battery is the lithium iron phosphate lithium ion battery. The name is too long, for short, the lithium iron phosphate battery. Because its performance is particularly suitable for power applications, the name is added to the "power" two words, that is, lithium iron phosphate power battery. It is also called the "lithium iron (LiFe) power battery".
The lithium iron phosphate battery is a lithium ion battery using lithium iron phosphate as a cathode material. The cathode materials of lithium ion batteries include lithium cobalt, lithium manganate, lithium nickel, three yuan material, lithium iron phosphate and so on. Lithium cobaltate is the cathode material used by most of the lithium ion batteries at present.
Metal trading market, cobalt (Co) is the most expensive, and the storage volume is not much, nickel (Ni), manganese (Mn) is cheaper, and iron (Fe) storage is more. The price of the positive material is also in accordance with the price of these metals. Therefore, lithium ion batteries made of LiFePO4 positive material should be very cheap. Another feature of it is that there is no pollution to the environment.
As the battery requirements are: high capacity, high output voltage, good cycling performance, stable output voltage, high current charge discharge and electrochemical stability, the use of security (not due to overcharge and overdischarge and short circuit operation caused by improper combustion or explosion), wide temperature range, non-toxic or less toxic, no pollution to the environment. The lithium iron phosphate battery using LiFePO4 as anode in the performance requirements are good, especially in the high rate discharge discharge (5 ~ 10C discharge), stable discharge voltage, safe (no burning, no explosion), life (cycles), no pollution to the environment, it is the best. Is currently the best high current output power battery.
Structure and working principle
LiFePO4 as the anode, cathode and battery are connected by aluminum foil, intermediate polymer diaphragm, which separates the anode and the cathode of lithium ion, but Li can through the electronic e- couldn't pass on the right is made of carbon (graphite) battery cathode, anode and battery are connected by copper foil. Between the upper and lower ends of the battery is the electrolyte of the battery, and the battery is enclosed by a metal enclosure.
When the LiFePO4 battery is charged, the Li ion Li in the positive electrode migrate through the polymer diaphragm to the negative electrode. During the discharge, the lithium ion Li in the negative electrode migrate from the diaphragm to the positive electrode. The lithium ion battery is named after the lithium ion is moved back and moved when it is charged and discharged.
The nominal voltage of the LiFePO4 battery is 3.2V, the termination charge voltage is 3.6V, and the terminated discharge voltage is 2.0V. Due to the different quality and process of the positive, negative and electrolyte materials used by various manufacturers, their performance will be somewhat different. For example, the capacity of the same type (the standard battery for the same package) has a large difference (10% to 20%).
Here is to point out that there are some differences in the performance parameters of lithium iron phosphate batteries produced by different factories. In addition, some battery properties are not included, such as battery internal resistance, self discharge rate, charging and discharging temperature, etc.
There are large differences in the lithium iron phosphate battery capacity can be divided into three categories: small to a few tenths of a few Ma, Ma, large medium-sized tens of hundreds of ma. There are some differences in the similar parameters of different types of batteries.
Over discharge to zero voltage test:
The STL18650 (1100mAh) lithium iron phosphate power battery was used to test the discharge to zero voltage. Test conditions: the 1100mAh STL18650 battery is filled with the charge rate of 0.5C, and then the voltage of the battery is 0C with the discharge rate of 1.0C. Then the battery in 0V will be divided into two groups: one is stored for 7 days, the other is stored for 30 days; after the expiration, the charging rate of 0.5C is full, and then 1.0C is discharged. Finally, the difference between the two zero voltage storage periods is compared.
The test result is that after zero voltage storage for 7 days, the battery has no leakage, the performance is good, and the capacity is 100%. After storing for 30 days, it has no leakage, good performance, and capacity is 98%. After storing for 30 days, the battery will do 3 charging and discharging cycles again, and the capacity will return to 100%.
This experiment shows that the battery does not leak and damage even if the battery has been discharged (even 0V) and stored for a certain time. This is the characteristic that other kinds of lithium ion batteries do not have.
Zhejiang Godsend Power Technology CO.,LTD
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