As a LiFePO4 Battery Supplier, we improve the low-temperature performance of lithium iron phosphate battery packs from the positive, negative, electro-hydraulic, and binder.
The positive electrode is now nano-sized. Its particle size, electrical resistance, and AB plane axis length will affect the low temperature characteristics of the entire battery. Different processes also have different effects on the positive electrode. The low-temperature discharge characteristics of batteries made of lithium iron phosphate with a particle size of 100 to 200 nanometers are better, and 94% can be released at -20 degrees, which means that the nanometer particle size shortens the migration path. It also improves the performance of low-temperature discharge, because lithium iron phosphate discharge is mainly related to the positive electrode.
Considering the charging characteristics from the negative electrode side, the low-temperature charging of lithium batteries is mainly the negative electrode effect, including the particle size and the spacing of the negative electrode. Three different artificial graphites were selected as the negative electrode to study the different low-temperature characteristics of the interlayer spacing and particle size. Impact. From the perspective of the three materials, the granular graphite with a large interlayer distance has a smaller impedance in terms of bulk resistance and ion migration resistance.
In terms of charging, the lithium battery pack has little discharge problem in low temperature in winter, mainly due to low temperature charging. Because in terms of cross flow ratio, the cross flow ratio of 1C or 0.5C is very critical. It takes a long time to reach constant voltage. By improving the comparison of three different graphites, it is found that one of them has a greater improvement in the constant current ratio at -20 degrees From 40% to more than 70%, the interlayer distance increases, and the particle size decreases.
For the electrolyte, the electrolyte freezes at -20 degrees and -30 degrees, the viscosity increases, and the formation performance deteriorates. Electrolyte from three aspects: solvents, lithium salts, additives. The effect of the solvent on the low temperature of the lithium iron phosphate battery pack is more than 70% to more than 90%. There are more than a dozen points of impact. Second, different lithium salts have a certain effect on the characteristics of low temperature charge and discharge. Based on the fixed solvent system and lithium salt, low temperature additives can increase the discharge capacity from 85% to 90%. That is to say, in the entire electrolyte system, solvents, lithium salts and additives all have low temperature characteristics on our power batteries. There are certain effects, including the application of other material systems. "
In terms of adhesives, under the condition of 20 ° charge and discharge, the two dots have a cycle of more than 70 to 80. The entire pole piece has the status of adhesive failure, and the linear adhesive will not exist. this problem. In the whole system, from the improvement of the positive electrode, the negative electrode, the electrolytic solution to the binder, the LiFePO4 Battery monomer has a better effect. One is the charging characteristics, 0.5 at -20, -30, and -40 degrees. C charging constant current ratio can reach 62.9%, discharge at -20 degrees can discharge 94%, which is some characteristics of the rate and cycle. Our company also has LiFePO4 2000mAh 3.2V on sale, welcome to consult.
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