In lithium-ion batteries, cathode materials are often the bottleneck affecting battery energy density due to differences in positive and negative electrode capacities. Therefore, there are more or less differences in the characteristics of lithium ion batteries using different positive electrode materials. There are four common cathode materials, namely lithium cobalt oxide and lithium nickelate; lithium manganate with spinel structure; lithium iron phosphate with olivine structure; ternary material. So what exactly is a ternary material? As the name implies, a ternary material is a composite electrode material that is a mixture of three electrode materials. In theory, it has the characteristics and advantages of each electrode material. The most common ones are NCA and NCM.

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Recently, BYD said that the company's future plug-in hybrid vehicles will try to use ternary batteries. Previously, BYD has always favored lithium iron phosphate batteries. As a leading company in materials and new energy vehicles, why has it suddenly changed its attitude? NCM is currently the most mainstream ternary material, and it has also been Think it is the future development trend. NCM refers to a nickel-cobalt-manganese ternary material. Different electrode characteristics were obtained by blending the ratios of nickel, cobalt and manganese.

At present, the domestic route is still dominated by lithium iron phosphate. Lithium iron phosphate has good cycle stability and low cost. Its theoretical energy density is about 160Wh/kg, which almost reaches the ceiling of energy density. For example, after doping one or more ions, a higher capacity is obtained, and the specific discharge capacity of 1 C exceeds 120 mAh/g. However, it should be noted that increasing the specific energy does not necessarily increase the energy density of the battery, and the problems of stability, safety, material cost, and complexity of the processing technology remain to be solved. Therefore, these exciting laboratory data, there is still a long way to go to become a product parameter.

The congenital deficiency of lithium iron silicate makes more companies pay attention to ternary materials. Most manufacturers of lithium iron phosphate have begun to pay attention to the development of ternary materials. Some of them (such as Tianjin Lishen, AVIC Lithium) have begun mass production of ternary material lithium batteries.

The difference between ternary materials and phosphoric acid materials.

In terms of material properties alone, ternary materials have great advantages, especially specific capacity and compaction density. The maximum theoretical capacity of lithium iron phosphate is 170,155, which is basically the upper limit of lithium iron phosphate. At present, the only technical breakthrough is the compaction density. There is no substantial progress.

The difference in the standard voltage is even more so that the "physiological" short board cannot be changed. Comparison of ternary and lithium iron phosphate 18650 batteries (compared with the batteries of some top ten companies)

From the chart:

The basic capacity of the ternary cell is about 2200mAh, the LFP cell is 1500mAh, which is 45% higher than the LFP cell. Basically, on the 18650 battery, the LFP cell has no advantage. The number of LFP cell cycles is three times that of the ternary cell. As far as we know, the number of ternary battery cycles can be 800-1000.

Comparison of ternary and LFP other power batteries: The important indicators for electric vehicle batteries are weight, space and safety. Capacity comparison under unit weight:

LFP battery: capacity / weight = 50/1.46 = 34.2Ah / Kg

Ternary battery: capacity / weight = 42 / 0.86 = 48.8Ah / Kg

Unit capacity ratio: (48.8-34.2) / 34.2 = 42.6%, from the perspective of unit capacity, the ternary is 42.6% higher than LFP.

Change to unit watt hour calculation: capacity / weight * standard voltage

LFP battery: 34.2*3.2=109.4wh/Kg ternary battery: 48.8*3.65=178.2wh/Kg

From the unit watt hour, the ternary is higher than the LFP battery (178.2-109.4)/109.4=62.9%.

Calculated from the space, in the same capacity, LFP batteries occupy 48.6% more space than ternary cells.

Safety issues: From the point of view of physicochemical properties, LFP materials are safer than ternary materials, this is undeniable, but even in the case of safety issues, not only positive electrode materials, including electrolytes, diaphragms, PACK, BMS vehicles exist. A certain security issue. Moreover, foreign ternary material batteries are used much more on new energy vehicles than lithium iron phosphate batteries.

From the current report that the new energy car is on fire, the LFP battery car is not lower than the ternary battery new energy car, the author will not list them one by one. Another reason why BYD considers ternary materials may be related to expected changes in state subsidy policies. One of the new technical inspection indicators has been controversial-----------------------------------

There are two main requirements for the energy consumption index in the draft subsidy: the power consumption per ton of kilometers is not more than 13kwh, and the power consumption of 100 kilometers is set in sections (M stands for the whole set quality; Y stands for the power consumption)

As an energy consumption indicator, comparing the power consumption of 100 kilometers and the power consumption of 100 kilometers per kilometer, the quality of the vehicle is introduced. Is the survey indicator reasonable? The standard has pointed out that this is to encourage large cars and small cars. . If a small car increases the mass of the car body in order to achieve the target, it will increase the energy consumption, which runs counter to the lightweight development route of the car. There are also some experts who have a clear approval for the 100-kilometer power consumption index. Cui Dongshu, secretary-general of the National Passenger Vehicle Market Information Association, believes that “the indicator of electricity consumption per 100 kilometers is relatively reasonable and is conducive to standardizing the market segment of electric vehicles. Prevent the low-speed electric vehicle simple set of catalogues from entering the range of state-supported new energy vehicles."

The pursuit of high energy and high performance is the inevitable direction of technological development. Ternary materials are also an important direction for electrode materials. Lithium iron phosphate and lithium cobalt oxide can't give us any surprises in the future. Besides production, there are not too many "story" to talk about. Therefore, whether it is enterprises, universities, research institutions, or financial institutions, it is inevitable to invest resources in ternary materials for their own interests.

For the market alone, compared with the increased cruising range, the electric car that is more concerned may be that after using the ternary material, is the car more expensive, the battery life is shorter, is it more unsafe? It is. After full marketization, ternary materials will inevitably affect the market share of lithium iron phosphate batteries, but I believe that the two technologies will exist simultaneously. With the refinement of the application market in the future, various technologies “have their own functions” and have opened up new fields in their respective fields.

With the advancement of various electrode material technologies, the life of lithium-ion battery will come to an end. If you solve the problem of electric vehicles, you should hope that the new electrochemical system and new battery technology will emerge. The question is, is it first to develop electric vehicles with technology, or to develop battery technology after having electric vehicles? Hybrid technology based on nickel-hydrogen batteries has created a market myth of electric vehicles and needs to fully understand the market. There are enough resources to maintain. How to solve the problem of "want to do", "do it", "do it", and "do it" may be a priority for us to take precedence over technology itself.

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