The advantages and disadvantages of lithium iron phosphate batteries are summarized as follows:
The function of lithium-ion power battery mainly depends on the information of positive and negative poles. Lithium iron phosphate as the information of lithium-ion power battery has only appeared in recent years. The domestic development of large capacity lithium iron phosphate battery is July 2005.
Its safety function and cycle life are not comparable with other data, which are also the most important technical indicators of power batteries. The life of 1C charging and discharging cycle is 2000 times.
Single battery overcharge voltage 30V does not burn, puncture does not burst. Lithium iron phosphate cathode data make large capacity lithium ion batteries easier to use in series. To satisfy the need of frequent charging and discharging of electric vehicles. It has the advantages of non-toxicity, non-pollution, good safety function, wide source of raw materials, low price, long life and so on. It is the ideal positive material for the new generation of lithium ion batteries。
Lithium iron phosphate power battery pack:
First, the advantage of lithium iron phosphate battery
Lithium iron phosphate battery is used to make lithium ion secondary battery. Now the primary direction is power battery, which has great advantages over NI-H and Ni-Cd battery.
Seven advantages of lithium iron phosphate power battery
1, the number of longevity. The longevity number of lead-acid batteries has a cycle life of about 300 times, and the highest is 500 times. The lithium iron phosphate power battery produced by Shandong Haiba Energy Group Co., Ltd. has a cycle life of more than 2000 times, and the standard charge (5 hour rate) ), can reach 2000 times. The same quality lead-acid battery is "new half year, old half year, protection and protection for half a year", up to 1 - 1.5 years, and lithium iron phosphate battery under the same conditions, will reach 7-8 years. Comprehensive consideration, the functional price ratio will be more than 4 times that of lead-acid batteries.
2. Use safety. Lithium iron phosphate completely treats the safety hazard of lithium cobaltate and lithium manganate. Lithium cobaltate and lithium manganate will blast under intense collision, posing a threat to the safety of customers, and lithium iron phosphate has been strictly Safety tests, even in the worst traffic accidents, will not blast.
3, can be a large current. 2C fast charge and discharge, under the special charger, 1.5C charging within 40 minutes can make the battery overflow, the starting current can reach 2C, and the lead-acid battery does not have this function.
4, high temperature resistance. Lithium iron phosphate has an electric heating peak of 350 ° C - 500 ° C, while lithium manganate and lithium cobalt oxide are only around 200 ° C.
5, large capacity.
6, no recall effect.
7, green and environmental protection.
Second, the defects and improvement measures of lithium iron phosphate battery
Lithium iron phosphate batteries also have their drawbacks: for example, the lithium iron phosphate cathode material has a small tap density, and the equivalent capacity lithium iron phosphate battery has a larger volume than a lithium ion battery such as lithium cobalt oxide, and thus has no advantage in terms of a micro battery.
Poor conductivity and slow dispersion of lithium ions. When the high rate charge and discharge, the practical specific capacity is low, this problem is a difficult point that restricts the development of the lithium iron phosphate industry. The reason why lithium iron phosphate has not been widely used so late is a primary problem. However, poor conductivity has now been treated quite perfectly: it is the addition of C or other conductive agents. Now in the practice of production, the addition of organic carbon source and high-valent metal ions in the precursor to improve the conductivity of the data (A123, Yantai Zhuoeng is choosing this method), research shows that the conductance of lithium iron phosphate The rate is increased by seven orders of magnitude, so that lithium iron phosphate has the conductivity characteristics near lithium cobaltate.
The laboratory reported that when 0.1C is charged and discharged, it can reach a specific capacity of 165mAh/g or more, and the practice reaches 135-145mAh/g, which is basically close to the level of lithium cobalt oxide; however, the problem of slow dispersion of lithium ions has not been obtained yet. For good treatment, the treatment scheme adopted now has nanometer LiFePO4 grains, and then reduces the dispersion distance of lithium ions in the grains. In addition, it is doped to improve the dispersion channels of lithium ions. The latter method looks effective and Not obvious. There has been more research on nanotechnology, but it is difficult to apply it to practical industrial production. Now, as long as A123 claims to have mastered the nanotechnology industry skills of LiFePO4.
The tap density is low. Generally only reach 0.8-1.3, the low tap density can be said to be a big defect of lithium iron phosphate. All lithium iron phosphate cathode data have determined that it has no advantage in small batteries such as mobile phone batteries, so its scope of application is limited to a certain extent. Even if it has low cost, good safety function, good stability and high cycle number, if the volume is too large, it can only replace lithium cobaltate in a small amount. But this defect does not stand out in terms of power batteries. Therefore, lithium iron phosphate is primarily used to make power batteries.
Lithium iron phosphate battery has poor low temperature function. Although various methods (such as lithium, iron, and even phosphoric acid doping improve the ion and electron conductivity functions, the particle size of the primary or secondary particles is modified and the useful reaction area is manipulated, and additional conductive agents are involved. Adding electronic conductivity, etc.) to improve the low temperature function of lithium iron phosphate, but the inherent characteristics of lithium iron phosphate data, the resolution of its low temperature function is inferior to other positive electrode materials such as lithium manganate.
In general, regarding a single battery cell (note that the battery is single rather than the battery pack, the measured low temperature function may be slightly higher for the battery pack, which is related to the heat dissipation condition), the capacity at 0 °C is adhered to The rate is about 60 to 70%, 40 to 55% at -10 ° C, and 20 to 40% at -20 ° C. Such low temperature function is obviously not satisfactory for the operation requirements of the power source.
At present, some manufacturers have improved the low temperature function of lithium iron phosphate by improving the electrolyte system, improving the positive electrode formula, improving the data function and improving the design of the cell structure, but it has not yet been truly satisfactory.
There are common problems with batteries. The single-cell lithium iron phosphate battery life is now more than 2,000 times, but the battery life will be greatly reduced, it may be 500 times. Because the battery pack is made up of a large number of single cells, its working state is better than a group of people tied up with ropes to run, even if everyone is a sprinter, if everyone's movements are not common, the troops will not run fast, all Speed is even slower than the slowest individual player.
The same is true for the battery pack, as long as the battery functions are at the same height, the lifespan can be close to the level of the single battery. Under the existing conditions, due to various reasons, the manufactured batteries have poor commonality, which in turn affects the battery function and the total lifespan. Therefore, the application to the power car is inevitable.
Phosphorus lithium iron phosphate batteries are used more and more in the power products nowadays. In addition to the common electric vehicles, power tools, electric farm products, you can see more about the advantages and disadvantages of lithium iron phosphate batteries by looking at the website map.
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