Beginner's introduction: What is the ghost of nickel-cobalt-manganese-nickel-cobalt-aluminum ternary lithium battery?

by:CTECHi     2021-08-04

Lithium Power Grid News: With the widespread popularity of electric vehicles, many friends around me have been asking questions about power batteries. As an adventurer, Shock can ignore other things, but he is concerned about the reliability of his own adventure equipment. But it is the most important. Today I invited a good friend of mine to talk to you about the power battery.

Hello everyone, I am Xiaomangan, a star member of the power battery family, which is a nickel-cobalt-manganese ternary lithium battery (NCM). The history of our power battery family can be traced back to 1837. At that time, Robert Anderson of Scotland installed batteries and electric motors on the carriage and successfully transformed it into the world's first electric-powered vehicle. Then why do electric cars appear so late? Mainly because of key issues such as battery life, charging time, and safety. The members of our family were born to solve these problems.

Who are our family members?

The more well-known ones are lithium iron phosphate batteries, lithium titanate batteries, and my brother and I nickel-cobalt-aluminum ternary lithium batteries (NCA). We are composed of different elements, so we have different abilities and characteristics. For example, a lithium iron phosphate battery has the best temperament, but the electric energy (energy density) stored in the same volume is not enough, which affects the endurance of the vehicle. Let's talk about lithium titanate batteries, which can discharge quickly and provide high-power output, which can power buses and tanks. But its energy density is relatively low, and the raw materials and production costs are too high, so ordinary electric vehicles are not willing to use it. Finally, let’s talk about our brothers. Our temperament is good, the energy density is higher, and the battery life and stability can be balanced, so we have become the first choice for consumer-grade electric vehicle power batteries.

What kind of battery am I?

Scientifically speaking, a ternary lithium battery is a kind of lithium battery that uses nickel and cobalt as the positive electrode material and uses manganese or aluminum salts to stabilize the chemical structure. My strengths have been mentioned before, but I will mainly talk about my temper. My temper is okay, but if my brain is short-circuited or hit, punctured, or grilled, I will get angry and out of control. So in order not to make me angry, scientists have made a lot of effort in the selection of metal salts and packaging methods.

The choice of stability: aluminum or manganese?

As a ternary lithium battery, my brother and I still have different personalities and characteristics. The production of nickel, cobalt and aluminum not only requires high process requirements and high cost, but aluminum can play a role in improving the chemical stability of the battery cycle. When combined with the ternary system, the nickel content can be increased to a certain extent, thereby achieving higher battery energy density. However, the crystal structure of nickel-cobalt-aluminum is more unstable than that of nickel-cobalt-manganese, and it is prone to collapse at higher temperatures, leading to thermal runaway, which in turn causes risks. In contrast, although the manganese element in my body is more difficult to stabilize more nickel, the energy density of the current nickel-cobalt-manganese system is slightly lower, so the battery life performance is not as good as that of nickel-cobalt-aluminum, but the manganese-containing ternary system has better thermal stability. At the same time, the nickel content is less, so it is safer to be used as a power battery.

The choice of packaging: round or square, soft or hard?

The nickel, cobalt and manganese in my body will decompose when reaching a certain temperature, releasing oxygen, and oxygen will accelerate the reaction of the electrolyte under the action of high temperature, which will cause risks. So I need a more reliable packaging method. There are three most mainstream methods at the moment: cylindrical, rectangular and soft-packed.

Cylindrical type: The cells are packaged in a tightly wound manner, the internal arrangement is more compact, and the energy gathered is more. However, because the cylindrical battery is small in size, if you want to provide more energy, you need a large number of single batteries to form a battery pack, so the consistency of the battery is difficult to guarantee. Improper battery consistency management can lead to a variety of undesirable results, one of which is that the internal resistance increases and the internal temperature of the battery is out of control, causing danger.

Square shell type: The inner material can be rolled tightly, and the aluminum shell is not easy to expand, so it is relatively safe. This packaging method can be equipped with an explosion-proof plug inside. If there is a thermal runaway, the expansion air will be released from the fixed direction of the explosion-proof plug, which will not easily affect other cells.

Soft package type: The structure adopts aluminum-plastic film packaging. Because there is no space limitation of the aluminum shell, more energy can be loaded in the same volume, and the reaction is the most direct and thorough. But also because there is no aluminum shell restriction, the battery pack is prone to swelling or deformation, which may pose safety risks.

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