How much do you know about power battery technology for electric vehicles

The era of new energy vehicles has kicked off, and many people have begun to consider buying electric vehicles. Electric vehicles and fuel vehicles have little difference in appearance and feel similar to driving, but the things inside the car shell are completely different things. Usually we like to say that a car has “three big pieces”: engine, gearbox, and chassis; when it comes to electric vehicles, the “three big pieces” become: battery, motor, and Electronic control. If you add the chassis, it becomes “Four Pieces”.

Don’t know how to order batteries, is it a bit blind to buy an electric car? The regular electric vehicles that can be registered by the DMV use lithium batteries. Lithium-ion batteries, to be precise. Why is it called a lithium-ion battery? Because the charging and discharging process of this kind of battery is the process of lithium ions moving back and forth between the positive and negative electrodes. The positive and negative electrodes of the battery are the two homes of lithium ions. When charging, lithium ions move from the positive electrode to the negative electrode to live in, and when discharging, they move from the negative electrode back to the positive electrode to live.

Lithium-ion batteries are one of the most technologically advanced batteries available today. This kind of battery has high energy density, and can store more electricity; long cycle life, can be charged and discharged more times, and lasts for a long time. There are mainly two types of lithium batteries used in electric vehicles: lithium iron phosphate batteries and ternary lithium batteries. Hearing the name made people panic, and instantly wanted to find a middle school chemistry textbook to review. Forget it, it doesn’t matter if you don’t learn chemistry well, after all, you don’t need to answer a chemistry test paper to buy an electric car. Simply put, “lithium iron phosphate” and “ternary lithium” refer to the positive electrode material of the battery.

Lithium iron phosphate battery and ternary lithium battery can’t be simply said which is better, it can only be said that each is good at winning the game. Lithium iron phosphate batteries are superior in long life, good safety and low cost, but their energy density and low temperature performance are inferior; ternary lithium batteries are superior in terms of high energy density and more power storage, but their safety and lifespan are inferior.


Why is it called ternary lithium battery? Very simple, because the positive electrode material of the battery is ternary lithium; what is ternary lithium? That is, there are three elements, and they form a gang of complex oxides with lithium. Said to be three elements, it is not a fixed three elements, but divided into sects. Now there are mainly two hills: one for nickel, cobalt, and manganese, and one for nickel, cobalt, and aluminum.

Let’s talk about nickel-cobalt-aluminum first. my country’s nickel-cobalt-aluminum (according to the abbreviation of the element, also known as NCA in the industry) has a relatively short time. This kind of battery has some technical barriers. At present, it is mainly produced by companies in Japan and South Korea. Tesla is now using ternary lithium batteries. , which is the nickel-cobalt-aluminum battery provided by Japan’s Panasonic. The mainstream ternary lithium battery in China is the nickel-cobalt-manganese battery (NCM for short in the industry). Although both are called nickel-cobalt-manganese, nickel-cobalt-manganese is different from nickel-cobalt-manganese. The difference is mainly in the proportion of the three things in the positive electrode material.

If the ternary lithium battery is disassembled, there are mainly four parts: positive electrode, negative electrode, electrolyte, and diaphragm. The positive electrode and the negative electrode are not mentioned, it is a battery, and elementary school students know what it means; the electrolyte is like a road, and lithium ions move back and forth between the positive and negative electrodes, which is the road through the electrolyte; the principle of the diaphragm is more complicated , Everyone just needs to know that this thing is used to isolate the positive and negative poles. If it is not isolated, will it be short-circuited?

How much electricity a ternary lithium battery can store depends on the positive electrode material. The positive electrode material is the home of lithium ions. The more rooms in this home, the more lithium ions live, and the larger the battery capacity. And there are not many rooms, mainly depends on how the ratio of nickel, cobalt and manganese is matched. To put it simply, the nickel in the “ternary” mainly controls the capacity; cobalt, the main control is the life (charge and discharge times); manganese, the main control is the stability. In other words, the more nickel, the larger the battery capacity; the more cobalt, the longer the battery life; the more manganese, the better the battery safety.

In order to increase the capacity of the ternary lithium battery, it is necessary to increase the proportion of nickel in the positive electrode. So you can see that the proportion of nickel is constantly increasing. From the early NCM111, to the NCM523 and NCM611 in the past two years, and then to the NCM811, which has been launched this year, the energy density of the battery is getting higher and higher, and the use of nickel is becoming more and more vigorous. For example, Weilai’s ES8 still uses NCM523, and ES6 has become NCM811. GAC New Energy’s Aion S, Geely’s Geometry A, etc., have used NCM811 to increase the cruising range. Of course, the new car-making forces will not show weakness. Xiaopeng, Hezhong, etc. also have 811 battery models on the market.

More nickel is used, and the ratio of cobalt to manganese is bound to decrease. Will battery life and stability be affected? Theoretically yes, but it is not impossible to solve the problem technically, who knows! Which battery will be the winner? Now the leading role is undoubtedly the ternary lithium battery, and it is a “high nickel” ternary lithium battery. On the one hand, this is due to policy reasons. Electric vehicles with long cruising range and high battery energy density can get more financial subsidies; Long, whose technology is advanced.

With the “slope” and withdrawal of the subsidy policy, the “high nickel” impulse of ternary lithium batteries may calm down. With the advancement of lithium iron phosphate technology, it is also expected to compete with ternary lithium for dominance. BYD revealed in August that the new generation of iron-lithium batteries to be launched from May to June next year will have a 50% increase in volume specific energy density, a lifespan of 1.2 million kilometers for 8 years, and a 30% cost savings. Some analysts say that the energy density of lithium iron phosphate is expected to be comparable to that of 622 ternary lithium batteries. Since this is the case, with the blessing of good safety, long life and low cost, lithium iron phosphate batteries may not return to the center of the stage.

In a few years, it will be time to look at solid-state lithium-ion batteries. Solid-state lithium battery, the electrolyte changes from liquid to solid, with large capacity, fast charging speed, and no risk of electrolyte leakage and fire, it can be described as an ideal power battery. Several companies around the world have launched prototype batteries for solid-state batteries, and perhaps within three or five years, such batteries will emerge.

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