How to distinguish lithium iron phosphate battery from ternary lithium battery
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2022/07/27 15:48:07
How to distinguish iron phosphate lithium ion battery from ternary lithium ion battery?
Iron phosphate lithium ion battery
Iron phosphate lithium ion battery refers to lithium ion battery which uses lithium iron phosphate as cathode material. It is characterized by no cobalt and other valuable elements, low raw material price, and phosphorus, iron exist in the earth's rich resource content, there will be no supply problem. Its working voltage is moderate (3.2V), unit weight under the electric capacity is large (170mAh/g), high discharge power, fast charging and long cycle life, high stability in high temperature and high thermal environment. Iron phosphate lithium ion batteries have at least the following five advantages: higher safety, longer service life, free of any heavy metals and rare metals (low raw material cost), support for fast charging, a wide range of operating temperatures.
The disadvantage is that 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 cost of material preparation is higher than that of battery manufacturing, the battery yield is lower, and the consistency is poor. Poor product consistency; Intellectual property issues.
Ternary polymer lithium ion battery
Lithium nickel-cobalt manganate (Li (NiCoMn) O2) lithium ion battery with ternary cathode material is used. According to Ouyang Minggao of Tsinghua University, the "three yuan" material in this investigation refers to the "three yuan power lithium battery", which is commonly said that the positive electrode is three yuan and the negative electrode is graphite. But in the actual research and development application, there is a positive electrode is three, the negative electrode is lithium titanate, commonly known as "lithium titanate", its performance is relatively safe, relatively long life, does not belong to the common said three materials. Ternary lithium ion battery has high energy density and better cycle performance than normal lithium cobalt. At present, with the continuous improvement of the formula and the perfect structure, the nominal voltage of the battery has reached 3.7V, and the capacity has reached or exceeded the level of lithium ion cobalate battery.
Ternary lithium ion battery is a lithium ion battery that uses lithium nickel-cobalt manganate as the positive material and graphite as the negative material. Unlike lithium iron phosphate, ternary lithium-ion batteries have a high voltage plateau, which means that for the same volume or weight, ternary lithium-ion batteries have more specific energy and power. In addition, ternary lithium-ion batteries also have great advantages in high rate charging and low temperature resistance.
The disadvantage is that ternary material power lithium ion batteries are nickel-cobalt-aluminate lithium ion batteries, nickel-cobalt-manganate lithium ion batteries, etc. 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 gas, and then cause danger, and the cost is high at present.
Conclusion: In comparison, ternary polymer lithium ion battery is indeed better than iron phosphate lithium ion battery, but its development has been hindered with the new energy, but generally speaking ternary polymer lithium ion battery is better.
● Energy density comparison
The energy density of iron phosphate lithium ion battery is 120Wh/kg, and 80Wh/kg after grouping. The energy density of ternary lithium ion battery is 180Wh/kg and 110Wh/kg when it is grouped. In terms of energy density, teradic lithium-ion batteries are statistically superior to ferric phosphate lithium-ion batteries. At present, the national new energy vehicle subsidy standard depends on the energy density of the battery system. The specific policy is that if the energy density of the battery system of the new energy passenger car 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 buses whose battery energy density is higher than 115Wh/kg will be subsidized by 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 the long-term use process. The growth of lithium dendrite in the charging and discharging process is easy to puncture the diaphragm, causing battery short circuit and causing safety hazards. The iron phosphate lithium ion battery has the advantages of high temperature resistance, strong safety and stability, and better cycling performance in practical use.
● Cost aspect
Because iron phosphate lithium ion batteries do not contain precious metals, the cost of raw materials can be compressed very cheaply. Teradic lithium ion batteries are lithium nickel-cobalt manganate as the positive material, graphite as the negative material of lithium ion batteries, so the cost will be much more expensive than iron phosphate lithium ion batteries.
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, It is currently impossible to completely replace lithium iron phosphate. In terms of comprehensive energy density, cycle life and low temperature performance, the comprehensive performance of terpolymer battery is better than that of lithium iron phosphate battery, but in terms of stability and cost, lithium iron phosphate still has a firm position.
Low temperature performance
The low temperature performance of iron lithium ion battery is hard. In Jiangsu and Zhejiang Province, 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 high power vehicle current. Ternary lithium ion battery in the same temperature, about 90% of the summer, there is a drop, but it is not too obvious. Further north, there's a bit more of a decline. Customers in different regions, when choosing lithium materials, this is a must be taken into account.
● Actual life
If the quality of iron lithium ion battery is relatively good, the attenuation amount can be controlled within 5% in one year and 15% in the second year. For ternary lithium-ion batteries, the decline is 7-10% in one year and 20-25% in two years. Of course, the specific and use load, use frequency has a relationship, here is just a general statement.
● Charging efficiency
In addition to battery life, charging is also an important link in the practical use of electric vehicles, and ternary lithium ion battery has a very big advantage over iron phosphate lithium ion battery in terms of charging efficiency. At present, the common charging method in the market is constant current and constant voltage charging. Generally, constant current charging is used at the beginning of charging. At this time, the current is larger and the charging efficiency is relatively higher. After the voltage reaches a certain value, reduce the current and change to constant voltage charging, so that the battery can be charged more fully. In this process, the ratio of the constant current charging capacity to the total battery capacity is called the constant current ratio. It is a key measure of how efficiently a battery is charged during the charging process. Generally, the higher the percentage, the higher the charge in the constant current phase, which proves the higher the charging efficiency of the battery.
In general, as the main force of the current power lithium battery, the energy density of iron phosphate lithium ion battery has basically reached the extreme of the theory, but due to the advantages of cost, safety and other aspects, it is still needed in industrial production. Taking various factors into consideration, the service characteristics of iron phosphate lithium ion battery can be roughly expressed as follows: relatively large size, poor low temperature performance, can maintain a relatively gentle decay rate in the life period, generally used for about 5 years is OK; The characteristics of the ternary system: small size, can be installed with a larger capacity, winter performance decline is not much, the initial capacity is larger, than iron lithium has obvious mileage advantage, later life will have a relatively significant decline, the general life of about 3 years.
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