What causes affect iron phosphate ion batteries low temperature performance do you know?

　　Author ：Iflowpower – Leverantör av bärbar kraftverk

Poor conductivity, lithium ion diffusion speed is slow. When high-rate charge and discharge, the actual amount is low, this problem is a difficult point to restrict the development of lithium iron phosphate industry. Lithium iron phosphate does not have a wide range of applications so late, this is an important issue.

However, poor conductivity is currently a relatively perfect solution: add C or other conductive agent. Currently, in the actual production process, improve material conductivity by adding organic carbon sources and high-priced metal ions in the actual production (A123, Yantai XionGong is using this method), the study shows that lithium iron phosphate conductors The rate is increased by 7 orders of magnitude, so that the lithium iron phosphate has a conductance property that is similar to lithium cobalt acid. Lab reporting When 0.

1c charge and discharge, the specific capacity of 165mAh / g is reached, and the actual reach 135-145mAh / g, which is basically close to lithium cobaltate; however, the problem of slow dissipation speed is still no longer Good solution, the current solution is important to have nanochemical LiFePO4 grains, thereby reducing the diffusion distance of lithium ions in grains, and then, it is doped to improve the diffusion channel of lithium ions, and the latter method does not seem to look. obvious. Nano has more research, but it is difficult to apply to actual industrial production, and only A123 has claimed to master LifePo4's nanochemical technology technology.

Lower vibration density. Generally only 0.8-1.

3, the low vibration density can be said to be a very shortcomings of lithium iron phosphate. All lithium iron phosphate positive materials determine that it has no advantage in small batteries such as mobile phone batteries, so the scope of use is limited by a certain extent. Even if its cost is low, good security, good stability, high cycle, but if the size is too large, only small amounts of lithium.

But this disadvantage will not protrude in the power lithium battery. Therefore, lithium iron phosphate is important for making power lithium batteries. Although people have passed various methods (such as lithium-bit, iron bit, even phosphoric acid-based doping to improve ions and electron conductive properties, by improving the particle size and morphology of primary or secondary particles, by adding additional conductive New electron conductivity, etc.

In general, regarding a single battery (note is a single only instead of battery pack, the measured low temperature performance may be slightly higher, this is related to heat dissipation conditions), and the capacity at 0 ¡ã C remains The rate is about 60 ~ 70%, - 10 ¡ã C is 40 ~ 55%, and 20 to 40% at 20 ¡ã C. Such low temperature performance clearly does not meet the requirements of the power supply. Some manufacturers have improved the low temperature performance of lithium iron phosphate by improving the electrolytic solution system, improving the positive recipe, improving material performance and improving the battery design, etc.

, but has not really met the demand. Battery consistency problem. The lithium phosphate ion battery life is currently more than 2,000 times, but the life of the battery pack will be greatly reduced, it is possible to be 500 times.

Because the battery pack is made of a large number of monomer battery strings, the working state is better than a group of people to run together with a rope, even if everyone is short running, if everyone's movement consistency is not high, the team is not running, overall The speed is even slower than the slowest single player running. The battery pack is reasonable, only when the battery is high, the life can be close to the level of the unitary battery. Under existing conditions, due to various reasons, the production of battery consistency is poor, which in turn affects the performance and overall life of the battery, so there is a certain obstacle to the power vehic.