With the rise of lithium iron phosphate batteries, how did ternary lithium batteries gradually become neglected?

The power battery of new energy vehicles is different from the engine of fuel vehicles. Due to physical limitations, it is difficult for power batteries to achieve revolutionary changes in a short period of time. After so many years of development of new energy vehicles in China, the only mainstream battery types are lithium iron phosphate batteries and ternary lithium batteries. It has to be said that compared with the "hundred flowers blooming" internal combustion engine industry, the power battery of new energy vehicles is still just a "younger brother".

Interestingly, power batteries did not follow the established development path, but kept swinging and jumping back and forth between lithium iron phosphate and ternary lithium. The overall development path is roughly: lithium iron phosphate battery ➡ ternary lithium battery ➡ lithium iron phosphate battery.

Such changes undoubtedly verify the development status of the new energy vehicle industry in recent years. At first, the insufficient range of new energy vehicles became the most important problem facing consumers. At this time, most car companies saw the advantages of the high energy density of ternary lithium batteries, so they turned to ternary lithium batteries.

The good times didn't last long. As the range of new energy vehicles increased, the failure rate of the products also increased. Regardless of the brand, as long as you search "xx space spontaneous combustion" on Baidu, there will definitely be a lot of related news. Major car companies have enjoyed the advantages of ternary lithium batteries, but they have also been overwhelmed by the problems that have followed. At this point, the disadvantage of poor reliability of ternary lithium batteries has been maximized.

Things took a turn for the better at the end of 2019, when two manufacturers brought major innovations to lithium iron phosphate batteries: CATL and BYD. They introduced CTP technology and blade battery technology respectively, which indirectly solved the shortcomings of lithium iron phosphate batteries, such as low energy density and serious endurance degradation at low temperatures, while maintaining the advantages of low cost and high safety.

As the leading and second largest companies in China's power battery industry, their technological trends have influenced many car companies, including Tesla, a major sales company.

So, how did the ternary lithium battery fall into the cold step by step, and how did the lithium iron phosphate battery achieve a counterattack step by step? Let's take apart the above development path and see from a technical perspective which type of battery is truly suitable for future new energy vehicles.

●Similarities and differences between the two

If you want to analyze the love and hate between lithium iron phosphate batteries and ternary lithium batteries, you must first understand the differences between them.

At the beginning, we would like to put forward a point of view that lithium iron phosphate batteries and ternary lithium batteries have their own advantages in different scenarios, and there is no question of one crushing the other, otherwise there would not be the "repeated jumps" of car companies.

Although the names are very different, in fact, lithium iron phosphate batteries and ternary lithium batteries only differ in the positive electrode material. As the name implies, the positive electrode material of lithium iron phosphate batteries is lithium iron phosphate, while the positive electrode material of ternary lithium batteries is nickel cobalt manganese (NCM) or nickel cobalt aluminum (NCA).

Because the essence of batteries is to produce chemical reactions, no matter what material is used as the positive electrode of the battery, the characteristics of the chemical elements are innate. Whether the battery is made into a cylindrical, rectangular, or even triangular shape will not affect the battery itself.

Putting aside some complicated chemical formulas, let's look at the results directly. The chemical reaction of lithium iron phosphate batteries determines that the stability and reliability of this type of battery are relatively good. Compared with ternary lithium batteries, lithium iron phosphate batteries have good high temperature resistance. Even if the surface temperature of the battery exceeds 500 degrees, it will not catch fire or self-ignite after being squeezed or punctured.

On the other hand, lithium iron phosphate batteries have excellent cyclability and reversibility. This feature allows the cycle life of energy-type lithium iron phosphate batteries to be as long as 3,000-4,000 times, and the cycle life of rate-type lithium iron phosphate batteries can even reach tens of thousands of times. Such physical properties are directly applied to new energy vehicles, that is, the battery's cruising range will not decrease with each charge.

Of course, its advantages are also its disadvantages. Since the crystal structure inside the battery is not active, it is safe enough, but the conductivity is too low. Especially in low temperature environments, the activity of the material decreases and the number of lithium ions that can move decreases, so lithium iron phosphate performs poorly in low temperature conditions.

In the early stages of the development of the new energy vehicle industry, most car companies used lithium iron phosphate batteries because of their low cost and good safety. However, as consumers became increasingly dissatisfied with the shorter driving range and the driving performance in low temperature environments, ternary lithium batteries began to gradually replace lithium iron phosphate batteries.

Ternary lithium batteries are made of nickel salt, cobalt salt, and manganese salt as raw materials, mixed in a certain proportion. Each element plays an important role, and the characteristics of each element also restrict the performance of the battery. In layman's terms, the materials of the ternary structure are very stable, and with the improvement of the energy of the positive electrode material by nickel, the ternary material has more power than lithium iron phosphate in the same volume.

Many car companies also like to indicate that ternary lithium batteries have higher power and longer driving range when promoting them. As the most important selling point of new energy vehicles, it has also become the object of pursuit by car companies.

So, if ternary lithium batteries are so good, why did they later face so much doubt? All of this started with the "spontaneous combustion" incident that we are all familiar with.

●The road to the "explosive popularity" of ternary lithium batteries

Ternary lithium batteries have become popular twice, once through word of mouth among consumers and once on the streets.

I don’t need to single out a particular car, because most new energy vehicles using ternary lithium batteries have experienced spontaneous combustion. Some were during charging, some were during driving. The working conditions are different, but the results are the same. Since ternary lithium batteries began to become mainstream, one vehicle after another has always appeared in the headlines.

Ternary lithium batteries are resistant to low temperatures, but not to high temperatures. In some extreme cases, the battery will release oxygen molecules, and the ternary material will become increasingly unstable at this time, and finally get out of control and catch fire. There are many reasons for this phenomenon, such as excessive temperature, internal short circuit, extrusion, puncture, etc. Most of the fires and spontaneous combustion incidents of new energy vehicles that we have seen are ultimately blamed on ternary lithium batteries.

So in summary, except for new energy vehicles, most models with power batteries will choose the battery type that suits them. For example, plug-in hybrid vehicles are almost all equipped with ternary lithium batteries, because the weight of lithium iron phosphate batteries is too large, which will greatly increase the fuel consumption of the vehicle. The light weight of ternary lithium batteries is undoubtedly revealed at this time.

Pure electric buses or transport vehicles generally use lithium iron phosphate batteries, because these vehicles have extremely high requirements for battery safety and cannot afford any mistakes. Therefore, despite the low charging efficiency and short cruising range, it is still the only choice for these vehicles.

In view of the poor reliability of ternary lithium batteries, many manufacturers have begun to look for supplementary solutions. In this process, lithium iron phosphate batteries, which were almost forgotten by pure electric family cars, have reappeared in the public's field of vision. This time, it comes with the advantages of ternary lithium batteries.

The advantages of lithium iron phosphate batteries are not just cheap

If you have read the recent data provided by the China Automobile Association, you will find that in October, 2.4GWh of lithium iron phosphate batteries were installed in vehicles, up 127.5% year-on-year. Among them, the Wuling Hongguang MINI EV with the highest sales and Tesla Model 3 and other models all chose lithium iron phosphate batteries. Since September this year, the demand for lithium iron phosphate batteries has continued to grow, and there was a shortage of supply.

This change is most directly related to two technologies, namely the CTP technology and blade battery technology we mentioned above, which come from CATL and BYD respectively.

First of all, CATL's CTP technology is to put the battery cells into the designed battery pack, and then assemble them into a new lithium battery according to the best arrangement and combination. After the corresponding optimization, the volume utilization rate of the battery will increase by 15% to 20%, the number of parts will be reduced by 40%, the production efficiency will be increased by 50%, and the cost of the battery will be greatly reduced.