Most mobile phones now use lithium batteries or lithium polymer compound batteries, which are batteries using lithium metal or lithium alloy as the negative electrode material and using a non-aqueous electrolyte solution. The earliest lithium battery came from the great inventor Edison. Due to the very active chemical properties of lithium metal, the processing, storage and use of lithium metal have very high environmental requirements. Therefore, lithium batteries have not been used for a long time.
With the development of microelectronics technology in the twentieth century, the number of miniaturized devices is increasing, which puts forward high requirements for power supply. Lithium batteries have then entered a large-scale practical stage, especially in the application of mobile phone batteries, and the current commonly used mobile phone lithium-ion battery specification is: lithium-ion secondary battery. The current commonly used mobile phone lithium-ion battery has a nominal voltage of 3.7V (or 3.6V), and a charge cut-off voltage of 4.2V (or 4.1V, depending on the brand of the battery cell with different designs). The charging requirements for lithium-ion batteries (GB/T182872000 specification) are first constant current charging, that is, the current is constant, and the battery voltage gradually increases with the charging process. When the battery terminal voltage reaches 4.2V (4.1V), change the constant current charging to Constant voltage charging, that is, the voltage is constant, and the current gradually decreases as the charging process continues according to the saturation degree of the cell. When it decreases to 0.01C, the charging is considered to be terminated. Note that C is a way of expressing the nominal capacity of the battery against the current. For example, if the battery has a capacity of 1000mAh, 1C is the charging current of 1000mA. Note that it is mA instead of mAh, and 0.01C is 10mA. Of course, the canonical representation is 0.01C5A. Then why do you think that 0.01C is the end of charging, in fact, this is stipulated by the national standard GB/T18287-2000. In the past, everyone generally ended with 20mA. The industry standard YD/T998-1999 of the Ministry of Posts and Telecommunications also stipulates that no matter how large the battery capacity is, the stop current is 20mA. The 0.01C specified by the national standard helps to charge more fully, which is beneficial for the manufacturer to pass the appraisal. In addition, the national standard stipulates that the charging time should not exceed 8 hours, that is to say, even if it has not reached 0.01C, the charging is considered to be over after 8 hours. Because batteries with good quality should reach 0.01C within 8 hours, it is meaningless to wait for batteries with poor quality. Therefore, remind everyone that charging should not exceed 8 hours, which is beneficial to the service life of the battery. Also read:oem lifepo4 10kwh supplier
Users who use electric vehicles in winter have a clear feeling that the battery life is shortened! Why is this?
For lithium batteries, there is currently no clear theory in the industry to support the inevitable relationship between internal resistance, discharge platform, life, and capacity under various temperature properties. The relevant calculation formulas and mathematical models are still in the exploratory stage. Generally speaking, lithium batteries are not sensitive to the temperature in the range of 0-40 °C, but once the temperature exceeds this range, the life and capacity will be reduced.
There is no way to quantify it specifically, because the activity of lithium-ion batteries is too high, and consistency is also the biggest problem. Even products of the same batch, the same material, and the same process, the performance will be very different.Also read:48v lifepo manufacturer
Many experiments have been done, and the low temperature performance of lithium batteries of different materials is also different. Now the most popular lithium iron phosphate has the worst low temperature performance. It is relatively high; the discharge capacity can reach 95% at 55 °C, and the attenuation at relatively low temperatures is still relatively small. This is still a product submitted for inspection. As we all know, the quality is much higher than that of normal products in the assembly line.
Relatively speaking, the low temperature performance of lithium manganate, lithium cobaltate and ternary products is better, but also limited; the sacrifice is high temperature performance. At present, lithium iron phosphate has high safety performance and good high temperature performance in the industry. In fact, the battery activity is not as high as the above three, and it is relatively safe. The overall performance is still not as good as manganese lithium or ternary.Also read:Lithium Ion Battery Packs Manufacturers
Therefore, some people reported that the lithium battery could not be charged in winter, and some of them had a battery management system because of product protection, and some of them could not be charged due to quality problems. The use time of lithium batteries in winter is necessarily shorter than that in summer. I would like to remind everyone that lithium batteries are best not to be charged in winter. Due to the low temperature, the lithium ions nested on the negative electrode will produce ion crystallization, which will directly pierce the diaphragm, which will cause a micro-short circuit in general, which will affect the life and performance, and may explode in serious cases!