Lithium-iron phosphate battery is used to make lithium-ion secondary battery, now the main direction is power battery, compared with Ni-H, Ni-CD battery has a great advantage.
Seven advantages of lithium iron phosphate battery:
The cycle life of the lead-acid battery is about 300 times, the highest is only 500 times, while the cycle life of the lithium iron phosphate power battery produced by Shandong Haiba Energy Group Co., Ltd. is more than 2,000 times, and the cycle life of the battery can reach 2,000 times when using the standard charge (5 hour rate). The same quality of lead-acid battery is "new half a year, the old half a year, maintenance and maintenance for half a year", the most is 1-1.5 years, and lithium iron phosphate battery under the same conditions, will reach 7-8 years. Overall, the cost of performance will be more than 4 times of lead-acid batteries.
Two, the use of safety, lithium iron phosphate completely solved the safety problems of lithium cobalt acid and lithium manganese acid, lithium cobalt acid and lithium manganese acid in a strong collision will produce an explosion to the safety of consumers, and lithium iron phosphate through strict safety tests even in the most severe traffic accidents will not produce an explosion.
Three, can be high current 2C fast charge and discharge, in the special charger, 1.5C charging within 40 minutes can make the battery full, starting current up to 2C, and lead-acid battery now without this performance. Four, high temperature resistance, the peak value of lithium iron phosphate can reach 350℃ - 500℃ and lithium manganese acid and lithium cobalt acid only about 200℃. Five, large capacity. No memory effect. Seven, green environmental protection.
The disadvantages of lithium iron phosphate battery and improvement measures lithium iron phosphate battery also has its disadvantages: for example, lithium iron phosphate cathode material vibration density is small, the volume of equal capacity of lithium iron phosphate battery is greater than lithium ion battery such as lithium cobalt acid, so there is no advantage in the micro battery.
The performance of lithium-ion battery mainly depends on the anode and anode materials. LiFePO4, as the material of lithium-ion battery, only appeared in recent years. It was in July 2005 that China developed a large capacity lithium-iron phosphate battery. Its safety performance and cycle life are incomparable to other materials, which are also the most important technical indicators of power batteries. 1C charging and discharging cycle life up to 2000 times. A single battery will not burn over charging pressure of 30V, and puncture will not explode. LiFePO4 cathode material makes large capacity lithium-ion battery easier to use in series. To meet the needs of frequent charging and discharging of electric vehicles. It has the advantages of non-toxic, pollution-free, good safety performance, wide source of raw materials, low price, long life and so on. It is an ideal cathode material for the new generation of lithium ion batteries. This project belongs to the development of functional energy materials in high and new technology projects, and is the key support field of the national "863" plan, "973" plan and "eleventh five-year plan" high technology industry development plan.
Poor electrical conductivity, slow diffusion rate of lithium ion. The actual specific capacity of high rate charge and discharge is low, which is a difficult problem restricting the development of lithium iron phosphate industry. One of the main problems is that lithium iron phosphate has not been widely used at this late stage. However, the conductivity of the poor has been relatively perfect solution: is to add C or other conductive agent. At present in the actual production process by adding the organic carbon source in the precursor and high metal ion doping method to improve the electrical conductivity of the material (A123, yantai zhuo is using this approach), research has shown that the conductivity of the lithium iron phosphate increased 7 orders of magnitude, to have and cobalt acid lithium iron phosphate lithium similar conductivity properties. It is reported in the laboratory that the specific capacity can reach more than 165mAh/g when charging and discharging at 0.1C, which actually reaches 135-145mAh/g, basically close to the level of lithium cobaltate. However, the problem of slow diffusion rate of lithium ions has not been well solved so far. The current solutions mainly include nanocrystallization of LiFePO4 grains to reduce the diffusion distance of lithium ions in grains, and doping to improve the diffusion channel of lithium ions. The latter method seems to have no obvious effect. There have been many studies on nanocrystallization, but it is difficult to apply it to actual industrial production. Currently, only A123 claims to have mastered the nanocrystallization industrial technology of LiFePO4.
The vibration density is low. Generally can only reach 0.8-1.3, low vibration density can be said to be a big disadvantage of lithium iron phosphate. All lithium iron phosphate cathode materials determine that it does not have an advantage in small batteries such as mobile phone batteries, so its use is limited to a certain extent. Even though it has low cost, good safety performance, good stability and high cycle times, it can only be replaced in a small amount if the volume is too large. But this drawback is not particularly noticeable in power batteries. Therefore, lithium iron phosphate is mainly used to make power batteries.
