Lithium ternary battery and lithium iron phosphate battery which is better

At present, there are two mainstream battery technology routes in new energy vehicles, lithium iron phosphate battery and lithium ternary battery. Although these two batteries compete in many application fields, the competition in the field of new energy vehicles is the main line, because this is the largest lithium battery application scenario in China. Since there is competition, there must be comparison. The cost performance of the battery can be compared by the price of the car, and from the performance comparison of lithium ternary battery and lithium iron phosphate battery which is better, through setting conditions to get the actual parameters of the two kinds of battery is clear. According to the experiments of relevant laboratories, new energy automobile manufacturers and power battery manufacturers, although there are inevitably subtle differences in specific parameters in each test, the judgment of the performance of the two batteries tends to be the same. For this reason, we take representative parameters for comparison.

1. BYD for passenger cars and Tesla for private cars. That's the difference in volume. From the current technology, the energy density of ternary lithium battery is generally 200Wh/kg, and may reach 300Wh/kg in the future. At present, lithium iron phosphate battery is basically hovering at 100~110Wh/kg, and some can reach 130~150Wh/kg, but it is very difficult to break through 200Wh/kg. As a result, ternary material power cells can provide twice as much space as lithium iron phosphate, which is important for cars with limited space. Tesla produces ternary lithium batteries, and BYD produces lithium iron phosphate batteries. Therefore, it is said that “BYD for passenger cars and Tesla for private cars".

2. And also because of the high energy density, the weight is much lower. Light weight and small occupation of space determines that the new energy vehicles with ternary lithium batteries consume less electricity, so they are faster and have stronger endurance. Therefore, ternary lithium batteries can be used in cars to run farther, while lithium iron phosphate new energy vehicles are still basically used in city buses at present, because one battery life is not far, it is necessary to have a charging pile within a short distance to charge.

3. Of course, passenger buses use lithium iron phosphate batteries for safety reasons. Tesla cars have caught fire more than once. The reason is that Tesla's battery pack consists of 7,000 or so 18,650 ternary lithium batteries. If these units or whole battery group short circuit can produce open fire, with extreme collision accident, short circuit can cause fire. The lithium iron phosphate material will not burn in short circuit, high temperature resistant performance is better than that of ternary lithium battery is superior.

4. Although lithium iron phosphate battery high temperature resistant, but the ternary lithium battery low temperature resistant performance is better, a major technical route. The manufacture of lithium-ion batteries at low temperature at minus 20 ° C, the ternary lithium battery can release 70.14% of capacity, and lithium iron phosphate batteries can only release the 54.94% capacity, and due to the low temperature condition, the ternary lithium battery discharge platform is much higher than the lithium iron phosphate battery and the voltage platform start up faster.

5. The ternary lithium batteries have higher charging efficiency. Lithium battery charging uses current limiting pressure limiting method, namely in the first stage to do constant current charging, the current is big and high efficiency, constant current charging after reaching a certain voltage, constant voltage charging into the second stage. At this point, the current is small and efficiency is low. Therefore, the charging efficiency is measured by constant current charging power and the ratio of the total capacity, which is called a constant current ratio. Experimental data show that, under10 c charging condition difference is not apparent, but more than 10 c there’s a difference, charging at 20 c, ternary lithium battery of constant current ratio is 52.75%, while the lithium iron phosphate battery constant current ratio is 10.08%, the former is five times more than the latter.

In terms of cycle life, lithium iron phosphate battery is superior to lithium ternary battery. The theoretical life of a ternary lithium battery is 2,000 cycles. But basically at 1000 cycles, the capacity goes down to 60 percent. Even Tesla, the best brand in the industry, can only maintain 70% of the power after 3,000 cycles, while lithium iron phosphate battery still has 80% capacity after the same cycle.

The comparison of the above six aspects can be roughly concluded that the relative advantages of the two can help answer the question of which is better, lithium ternary battery or lithium iron phosphate battery: lithium iron phosphate battery safety, long life and high temperature resistant; The ternary lithium battery charge light weight, high efficiency and low temperature resistance. Therefore, the adaptability of the two is the reason why they coexist in the market.

Although domestic subsidies for new energy vehicles have begun to decline, consumers have also begun to accept the popularity of new energy vehicles due to the increasingly rich infrastructure and a wealth of alternative models. In addition to being restricted areas cannot buy fuel alternative solutions for cars, new energy vehicles also have many unique advantages. Quiet environment, the types of clean energy and low transport costs, and even started large instantaneous output torque, which gain the favor of many friends driving fuel cars.

As the source of power, battery of electric vehicle and naturally is one of the most important parts. Range of electric cars such as charge and discharge all use are also connected with the performance of the battery. The current domestic power battery is mainly divided into two factions, depending on the cathode material is divided into pie and ternary lithium iron phosphate material. Although both belong to the secondary battery, can be used to charge and discharge repeatedly but due to differences in materials, in the final reflection to use the level of performance still have much difference.

The ternary lithium battery or lithium iron phosphate batteries?

If you want to understand which battery is better, we should first have a simple understanding of the difference between the two.

lithium iron phosphate battery refers to lithium ion battery with lithium iron phosphate as the positive electrode material. This type of battery is characterized by the absence of precious metal elements (such as cobalt, etc.).Since it does not contain precious metals, the raw material cost of lithium iron phosphate batteries can be compressed very cheaply. In practical use, lithium iron phosphate battery has the advantages of high temperature resistance, strong safety and stability, low price and better cycling performance.

The ternary lithium battery refers to the use of nickel cobalt manganese acid lithium as the anode material, graphite as the cathode material of lithium battery. Unlike the lithium iron phosphate, ternary lithium battery voltage platform is very high, which means under the same volume or weight, the specific energy and specific power of ternary lithium battery are larger .In addition, in the big charge ratio and low temperature resistance, etc., the ternary lithium battery also has a great advantage.

I've always thought that technology is not good or bad and only applicable to different product or environment. There is no such thing as a better or worse battery. Just to put it into practical use, ternary lithium battery is more suitable for current and future household electric vehicles than lithium iron phosphate battery.

Why is the ternary lithium battery more suitable for household electric car?

First, low temperature discharge performance is better

China has a vast territory and a complex climate. The temperature varies greatly from the northernmost three northeastern provinces to the southernmost Hainan islands. In Beijing for example, as the main electric car market Beijing summer maximum temperature around 40 ℃, while winter is basic about 16 ℃ below zero, even lower. Such a temperature range is obviously suitable for low-temperature lithium ternary batteries with better performance. The high-temperature performance of lithium iron phosphate battery in Beijing in the winter would seem to be some lack of power.

"Relative capacity of 25 ℃" refers to the different temperature conditions to devolve electricity capacity and 25 ℃ when the ratio of discharge capacity. The numerical can accurately reflect the attenuation of battery under the condition of different temperature range, the more close to 100%, the better the cell performance.

25 ℃ as a benchmark in normal temperature, two types of cells in 55 ℃ high temperature lowering electricity and room temperature 25 ℃ to devolve electricity, almost no difference between the discharge capacity. But at 20 ℃ below zero, the ternary lithium battery and lithium iron phosphate battery has obvious advantages compared.

Second, the energy density is higher

According to domestic 18650 cylindrical batteries ternary material leading enterprises- Bak battery providing information: its 18650 battery energy density has reached 232wh/kg, the subsequent will further increase to 293wh/kg, compared to the current domestic mainstream of lithium iron phosphate battery energy density is only 150wh/kg. According to the domestic battery industry experts, within the next few years, there is little hope that lithium iron phosphate batteries can achieve an energy density of 300wh/kg.

Different from huge electric buses, for household electric vehicles, space is always the first. Low energy density of lithium iron phosphate batteries will occupy the already little space, and because of the heavier quality, the discharge life will be greatly affected when using. Relatively high energy density ternary lithium batteries solve the weight problem but also for the family car to save space.

Third, charging efficiency is higher

In addition to battery life, charging is also an important link in the actual use of electric vehicles, and lithium ternary battery has a great advantage over lithium iron phosphate battery in charging efficiency.

Currently on the market more common way of charging for constant current constant voltage charging generally, constant current charging is adopted 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, the current is reduced to constant voltage charging, so that the battery can be fully charged. In the process, constant current charging ratio with a total capacity of the battery, is called a constant current ratio. It is the key value to measure the charging efficiency of a group of batteries during charging. Generally, the larger the percentage is, the higher the amount of charge in the constant current stage is, and the higher the charging efficiency of the battery is.

When the ternary lithium battery and lithium iron phosphate battery charging below 10 c, constant current ratio has no obvious difference, more than 10 c ratio charging, lithium iron phosphate batteries constant flow rate reduce rapidly, charging efficiency rapidly reduced.

Fourth, cycle life can be assured

For the family car, the rated cycle life of ternary material and lithium iron phosphate power battery far exceeds the actual use habits of users, so the service life can be completely assured. With Bak battery current high capacity battery 18650, for example, in the charge and discharge cycle after 1000, more than 90% of the battery capacity can still keep in the original. Because i am an electric car owner, all year round only the coldest winter of more than a month, frequent charging when opening the warm wind to reach 2 days, the rest of the time the basic charge 3-4 days. Assuming that the annual average of 3 days a charge to calculate, using a year need to charge about 6 times, cycle life of 1000 times after the use of about 8 years, which is basically more than the current average cycle of Chinese consumers.

Five, the safe enough material and process

Hardest part of the traditional internal combustion engine car is contains the huge energy of the fuel, ignition point or explosive of low liquid fuels like gasoline once leak is very easy to cause great potential safety hazard. Power battery and new energy vehicles, after complete battery management system (BMS) monitoring, each battery can get the most accurate control to prevent accidents.

In 18650 battery products of Bak, for example, In the process of single cell, Bak chooses to configure the protective additive and reactive additive respectively at the positive and negative poles to prevent the safety problems caused by electrolyte decomposition. At the same time add ceramic diaphragm and negative ceramic coating and other safety protection means to control the accident from the source. In addition, in the Bak miniature cylinder 18650 battery pack mode, each battery is kept at a safe distance from each other to ensure that a single battery accident does not affect other batteries.

The ternary lithium batteries are dominant power battery market in the future

In the field of electric vehicles, Tesla in the United States has been the benchmark of many domestic auto companies. When it comes to the strength of traditional car companies in researching and developing new energy vehicles, the launch of BMW i3 has become a textbook example. It is interesting to note that both models have a ternary lithium battery as the power battery. In contrast, the domestic market, many car makers such as JiangHuai, BYD, BeiJing also began to use lithium iron phosphate battery in its original car models to replace the ternary lithium battery.

Again, technology regardless of good or bad, only suitable or not suitable, it is no coincidence that the choice of battery type by domestic and foreign car companies coincides with each other. It is believed that in the near future, the battery market of electric vehicles will be reshuffled. Ternary lithium battery with its low temperature resistance, high energy density, high charging efficiency, good cycle life and stronger safety features, will also stand firm in the new market.

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