Author ：Iflowpower – Portable Power Station Supplier
A few days ago, at the 7th Global New Energy Automobile Conference (GNEV7), Watma Deputy General Manager Rao Minmin Published the theme of "Research on the Affecting Factors Affecting Lithium Ion Battery of Lithium Ion". The content is organized as follows: First, Rao Minmin is introduced, Watma was established in 2002, Headquarters in Shenzhen. There are currently more than 12,000 employees, and the first batch of battery companies entering the powerful lithium-ion battery directory in the Ministry of Industry and Information Technology, including more than 50,000 Watma batteries running on the road.
At present, most of the power lithium-ion batteries in the field of electric passenger cars are lithium iron phosphate. Rao Dingmin said that there are several comparative advantages of lithium iron phosphate: the cycle life and the magnification are better, but the low temperature will be a little longer than other battery systems. Secondly, the current electric vehicle has a relatively large difference in different temperatures.
Electric cars that can run 160 kilometers at room temperature may go to -20 degrees only run 60-80 kilometers, and the efficiency is more obvious. Secondly, the problem of low temperature charging in winter, including difficult to charge, safety incidents. For the lithium iron phosphate ion battery, Watma has made more detailed research on its low temperature characteristics: one is the influence of the positive electrode, the phosphate positive electrode itself is a poor electron conductivity, and the polarization is more likely to increase, reduce capacity Play; the second negative, negative pole this is important to low temperature charge, because it will affect security issues; the third is the piece of electrolyte, may increase at low temperature, lithium ion migration impedance will increase; Four is the binder, which is currently more affected by the low temperature performance of the battery.
The entire idea of Watma is from the positive electrode, negative electrode, electro-hydraulic, and adhesive four-piece low temperature performance of lithium iron phosphate ion battery. In terms of positive, it is now nanomechanically, its particle size, resistance, and AB planar axis growers will affect the characteristics of the entire battery low temperature. Lithium lithium iron phosphate is prepared by three processes.
From our entire preparation conditions, different lithium iron phosphate process nano-coated, we look from the axis of the AB, increased lithium The ion migration channel will become large, which will help improve the performance of the battery. Different processes have different effects on the positive electrode, and the low temperature discharge characteristics of the battery made by 100 to 200 nano-particle diameter phosphate, which can release 94% at -20 degrees, which is the particle diameter of nanofence shortening the path of the migration, It also improves the performance of low temperature and discharge, because the lithium phosphate discharge is related to the positive electrode. Considering charging characteristics from the negative electrode, Rao Dingyi believes that the low temperature charging of lithium-ion batteries is important, including the particle size of the particle size and the pitch of the negative electrode, select three different artificial graphite as an negative electrode to study different layer spacings and granules.
Influence of path to low temperature characteristics. From three materials, the grain graphite of the layer is large, from impedance, the body impedance and ion migration impedance are relatively small. In terms of charging, Rao Shanyi believes that the discharge problem is not large under low temperature in winter, it is important to low temperature charge.
Because in horizontal flow ratio, 1C or 0.5C cross-flow ratio is very critical, to constant pressure to be very long, by improving three different graphite comparisons, one of which is relatively large in -20 degree charging constant flow ratio Improved, from 40% to 70%, the increase in the layer spacing, there is also a decrease in particle size. This piece of the electrolyte, in -20 degrees, -30 degrees, the electrolyte, increased viscosity, and deteriorate the performance.
Electrolyte from three aspects: solvent, lithium salt, additive. Rao Dingmin said, "Through the experiment, we found that the solvent affects the low temperature of lithium iron phosphate ion batteries from 70%, there is more than 90%, there are more than a dozen points; secondly, different lithium salts have a certain characteristic of low temperature charge and discharge. Impact.
We fixed the solvent system and the lithium salt, and the low temperature additive can increase the discharge capacity from 85% to 90%, that is, in the entire electrolytic liquid system, solvent, lithium salt, and additives are for our power lithium ion battery. There is a certain impact on low temperature characteristics, including other material systems. "Adhesive, Rao Dingyi said there are three types, two points, a linear.
When the -20 degree charge and discharge, the two points have probably do more than 70 to 80 cycles, the entire pole is the status quo of the adhesive failure, and the use of linear binders do not exist this problem. After the entire system, from the improvement of the positive electrode, the negative electrode, the electrolyte to the binder, we have a better effect on the lithium iron phosphate ion battery monomer, one is charging characteristics, -20, -30, - 40 degrees at a temperature of 0.5C charging constant current ratio can reach 62.
9%, - 20 degree temperature discharge can be released 94%, this is some characteristics of the magnification and cycle. In general, new energy vehicles are normal operation in the north, not only the battery monomer can solve charging problems, and there is also the innovation of the BMS through Pack, and the innovation of the guarantee model. Guarantee new energy vehicles in northern low temperature normal operation.
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