How to distinguish lithium iron phosphate battery from ternary lithium battery
Back
2022/05/25 15:23:13
How to distinguish between lithium iron phosphate battery and ternary lithium ion battery?
Lithium iron phosphate battery
Lithium iron phosphate battery refers to lithium iron phosphate as the cathode material of lithium ion battery. It is characterized by no cobalt and other precious elements, low price of raw materials and rich content of phosphorus and iron resources existing in the earth, there will be no material supply problems. It has moderate working voltage (3.2V), large capacity per unit weight (170mAh/g), high discharge power, fast charging and long cycle life, and high stability in high temperature and heat environment. Lithium iron phosphate batteries have at least the following five advantages: higher safety, longer service life, no heavy metals and rare metals (low cost of raw materials), support for fast charging, wide operating temperature range.
The disadvantage is that the lithium iron phosphate battery has some performance defects, such as low vibration density and compaction density, resulting in low energy density of lithium ion battery; The material preparation cost and the battery manufacturing cost are high, the battery yield is low, poor consistency; Poor product consistency; Intellectual property issues.
Terpolymer lithium ion battery
Lithium ion batteries with lithium nickel-cobalt-manganate (Li (NiCoMn) O2) are used as cathode materials. According to Tsinghua University Ouyang Minggao explained: the investigation called "ternary" material, refers to the positive electrode is ternary, the negative electrode is graphite in the common term "ternary power lithium battery". And in the actual research and development application, there is a positive electrode is three, the negative electrode is lithium titanate, usually known as "lithium titanate", its performance is relatively safe, relatively long life, does not belong to the common three materials. Ternary lithium ion battery has high energy density and better cycle performance than normal lithium cobalt acid. At present, with the continuous improvement of formula and structure, the nominal voltage of the battery has reached 3.7V, which has reached or exceeded the level of lithium cobalt ion battery in capacity.
Ternary lithium ion battery refers to the lithium ion battery using nickel-cobalt-manganate as the positive material and graphite as the negative material. Different from lithium iron phosphate, ternary lithium ion batteries have a high voltage platform, which means that the specific energy and power of ternary lithium ion batteries are greater for the same volume or weight. In addition, ternary lithium ion batteries also have great advantages in large rate charging and low temperature resistance.
The disadvantage is that the ternary material power lithium ion battery is mainly nickel-cobalt-aluminate lithium ion battery, nickel-cobalt-manganate lithium ion battery and so on. Due to the unstable structure of nickel-cobalt-aluminum at high temperature, the high temperature safety is poor, and the high pH value is easy to make the monomer inflate, which leads to danger, and the current cost is high.
Conclusion: In comparison, ternary polymer lithium ion battery does have better characteristics than lithium iron phosphate battery, but its development has been hindered with new energy, but in general, ternary polymer lithium ion battery is better.
● Energy density comparison
Lithium iron phosphate battery monomer, energy density of 120Wh/kg, after group of 80Wh/kg; Ternary lithium ion battery monomer, energy density of 180Wh/kg, group energy density of 110Wh/kg. In terms of energy density, ternary lithium ion battery is superior to lithium iron phosphate battery. The current national subsidy standard for new energy vehicles depends on the energy density of the battery system. Its specific policy is that if the energy density of the battery system of new energy passenger cars exceeds 120Wh/kg, it can enjoy 1.1 times the subsidy, and between 90Wh/kg and 120Wh/kg, it can only enjoy 1 times the subsidy. Non-fast-charging pure electric bus battery energy density higher than 115Wh/kg will be subsidized 1.2 times.
Low security
The liquid electrolyte of ternary lithium ion battery is flammable and explosive, which is easy to trigger thermal runaway in long-term use. The growth of lithium dendrite is easy to Pierce the diaphragm in the charging and discharging process, resulting in short circuit of the battery, causing potential safety hazards. The lithium iron phosphate battery has the advantages of high temperature resistance, strong safety and stability, and better cycling performance in practical use.
● Cost
Because lithium iron phosphate batteries contain no precious metals, the cost of raw materials can be compressed very cheaply. And ternary lithium ion battery is lithium nickel-cobalt-manganate as anode material, graphite as anode material of lithium ion battery, so the cost will be much more expensive than lithium iron phosphate battery.
On market application, it is with the lithium iron phosphate batteries of the battery is relatively simple, not too much to protect auxiliary equipment, and although ternary batteries battery cell density is very high, but because of its poor safety is not high temperature resistant, so must be combined with a complex set of battery protection equipment, these devices are increased, the weight of the car makes three yuan weakened the battery on the energy density of advantage, At present, lithium iron phosphate cannot be completely replaced. In terms of energy density, cycle life and low temperature performance, the overall performance of ternary battery is better than lithium iron phosphate battery, but lithium iron phosphate still has a firm position in terms of stability and cost.
● Low temperature performance
The low temperature performance of iron lithium ion battery is hard. In Jiangsu and Zhejiang regions, under the temperature of 0-5 degrees in winter, the performance of iron lithium is about 75% of that in summer, and it will be even lower under the condition of large current of high-power cars. Ternary lithium ion batteries in the same temperature, about 90% of the summer, there is a decline, but not too significant. Further north, it's going to drop a little bit more. Customers in different regions, when choosing lithium materials, this must be taken into account.
● Actual life
If the quality of iron lithium ion battery is good, the attenuation can be controlled within 5% in one year, and within 15% in the second year. Ternary lithium ion battery type, a year in the decline of 7-10%, two years in 20-25%. Of course, specific and use load, use frequency has a relationship, here is only a general statement.
● Charging efficiency
In addition to the endurance, charging is also an important link in the actual use of electric vehicles, and ternary lithium ion batteries have great advantages over lithium iron phosphate batteries in charging efficiency. At present, the more common charging method on the market is constant current and constant voltage charging. Constant-current charging is generally adopted at the beginning of charging, when the current is large and the charging efficiency is relatively higher. After the voltage reaches a certain value, reduce the current to constant voltage charging, so that the battery can be more fully charged. In this process, the ratio of constant current charging capacity to total battery capacity is called constant current ratio. It is a key value to measure the charging efficiency of a battery in the charging process. Generally, the higher the percentage, the higher the charge in the constant current phase, which proves that the battery has a higher charging efficiency.
In general, as the main force of current power lithium battery, the energy density of iron phosphate lithium ion battery has basically reached the theoretical extreme, but due to the advantages of cost, safety and other aspects, it is still needed in industrial production. Based on a variety of factors, the use characteristics of lithium iron phosphate batteries can be roughly described as follows: relatively large size, poor low temperature performance, can maintain a relatively gentle decay rate during the life cycle, generally used for about 5 years is ok; The characteristics of ternary system: small volume, can hold a larger capacity, winter performance decline is not much, the initial capacity is large, compared with iron lithium has obvious mileage advantage, late life will have a significant decline, the general life of about 3 years.
Previous
