Is the ternary lithium battery disabled?

At the China Electric Vehicle Hundred People's Association, Zhang Xiangmu, Director of the Equipment Department of the Ministry of Industry and Information Technology, caused a lot of controversy. He said: "The Ministry of Industry and Information Technology will organize the risk assessment of the ternary lithium battery. Before the evaluation is completed, the ternary lithium battery bus will be suspended for the list of recommended models for the promotion and application of new energy vehicles."

In response to such news, the Ministry of Information of the Electric Vehicles has issued a special announcement saying that the 100 people will be just a platform, not representing any party. According to the current report, some companies have revealed that the relevant regulatory agencies have suspended the acceptance of the electric bus of the ternary materials, but the authenticity is still to be considered.

The objection to the use of ternary lithium batteries for commercial vehicles is mainly for security reasons. But why the ternary lithium battery will "lie down", from the principle.

How to evaluate "three-dimensional lithium battery is disabled on commercial vehicles"?

Ternary lithium VS lithium iron phosphate

The "three-element lithium battery" is a "ternary polymer lithium battery", which refers to a lithium battery using a nickel-cobalt-manganese ternary cathode material as a positive electrode material. This naming method is based on the "positive material" of the battery, in addition to lithium cobaltate, lithium manganate, and lithium iron phosphate batteries. In addition to the division according to the positive electrode material, the battery type can also be classified according to the shape, the outer material, and the electrolyte.

Ternary lithium, lithium manganate, and lithium iron phosphate can all be used in electric vehicles. Having said so much "lithium", you may be a little dizzy, but today's protagonist is a ternary lithium battery and a lithium iron phosphate battery.

The characteristics of the ternary lithium battery and the lithium iron phosphate battery are different, and the main contradictions are concentrated on "energy density" and "safety". Ternary lithium batteries have higher energy density, but safety is often suspected. Although the lithium iron phosphate battery has a small energy density, everyone says it is safer.

The difference in the so-called "safety" is mainly on the positive electrode material.

How to evaluate "three-dimensional lithium battery is disabled on commercial vehicles"?

Both materials will decompose when they reach a certain temperature, and the ternary lithium material will decompose at about 200 degrees. Moreover, the chemical reaction of the ternary lithium material is more intense, and oxygen molecules are released, and the electrolyte rapidly burns under the action of high temperature, and a chain reaction occurs. lithium iron phosphate will decompose at 700-800 degrees, and will not release oxygen molecules like ternary lithium materials, and the combustion is not so intense. To put it simply, the ternary lithium material is more likely to catch fire than the lithium iron phosphate material. Note that what we are referring to here is just "material."

From the general trend, domestic car manufacturers have turned to ternary lithium batteries, including Beiqi, BYD, Jianghuai and so on. The corresponding suppliers are also accelerating the production of ternary lithium batteries. For example, Yiwei Lithium will disclose in the semi-annual report that the second phase of the plant will mainly produce ternary lithium batteries.

As for lithium iron phosphate batteries, more and more active in the electric bus market. In November last year, the installed capacity of electric bus for lithium iron phosphate battery accounted for 64.9%, and the installed capacity for ternary lithium battery was only 27.6%. In contrast, in the pure electric passenger vehicle market, the installed capacity of the ternary lithium battery in November last year exceeded 76%.

How to evaluate "three-dimensional lithium battery is disabled on commercial vehicles"?

The problem is not which battery to use.

What we mentioned earlier is only the difference in characteristics of ternary lithium materials and lithium iron phosphate materials. The ultimate decision on safety is the entire power battery system.

Due to the characteristics of the lithium battery, it is necessary to have a BMS (Battery Management System). Key features include overcharge protection (OVP), over-discharge protection (UVP), over-temperature protection (OTP), and over-current protection (OCP) to instantly shut off current in the event of an accident.

If the battery is pyrolyzed, first ask if BMS is qualified.

Therefore, simply thinking that the ternary lithium battery is not safe is not suitable. The ternary lithium material is easy to pyrolyze, but it does not mean that the ternary lithium battery is not safe; the lithium iron phosphate material is not easy to pyrolyze, but it does not mean that the lithium iron phosphate battery is safe.

How to evaluate "three-dimensional lithium battery is disabled on commercial vehicles"?

The safety of the power battery is a system problem, not just the material. Judging from the previous spontaneous electric vehicle accident, there are ternary lithium batteries and lithium iron phosphate batteries. But the accident does not mean that a certain battery is a failure, there are too many factors involved, and the fuel car is self-igniting.

In fact, we should pay more attention to how to prevent the failed battery cells from harming other monomers. Due to the limitation of the process level, it is impossible to maintain the consistency of all battery cells at 100%.

At the recent GNEV conference, Li Shujun, general manager of Zhenhua New Energy, believed that the use of high-energy-density materials faced the choice of firecrackers or grenades. Therefore, the pragmatic approach is to focus on module security, and its focus is on failure isolation and security protection. Monomer failure is an unavoidable phenomenon, but module failure can be prevented by controlling the monomer.

From a macro point of view, if you use a ternary lithium battery to get a higher cruising range, then there are many other ways to achieve it, such as the lightweight of the car, etc., which is a systematic project.

However, if the ternary lithium battery is restricted from the policy, are these related electric vehicle technologies also facing "depletion"?

In short, the choice of battery type is to match the product positioning and technology. If the bus is prone to mass casualties, it is forbidden to use the ternary lithium battery on the bus. What about the car?

Thinking darkly, is there still the selfishness of "national protection"? If the limit ternary lithium battery is used in commercial vehicles, the biggest beneficiary may be the domestic lithium iron phosphate battery manufacturer, because the Korean battery company is the main ternary lithium battery and take the low-cost route. However, is this "protection" really beneficial to the development of domestic electric vehicles and related technologies?

In fact, technology can solve the inherent defects of materials, and the development of technology intervention through policy is worth considering.

In a group of car engineers' WeChat, there is a point: electric cars are not a bad thing, even early accidents are better than late events. The crux of the problem is not the type of battery used, but the fact that our electric vehicles are growing too fast, resulting in a large number of low-quality products, which are real safety risks.

The page contains the contents of the machine translation.