In the past, the main application areas of small cylindrical batteries were application scenarios such as mobile power supplies, smart homes, and two-wheeled vehicles, which did not require high mileage and output voltage.
With the continuous deepening of the electrification of human society, new application scenarios such as new energy vehicles, large-scale energy storage, and even electric aircraft, which require ultra-long battery life and high output voltage, are constantly emerging.
If we use the small cylindrical batteries of the past to store, it will require a large-scale series and parallel connection, which will pose great difficulties for the consistency of our batteries and the management of our power supply.
So this is one of the reasons for the rise of large-capacity square batteries.
For cylindrical batteries, if we want them to meet more and more such application scenarios, we must make corresponding breakthroughs in their size and capacity, such as the diameter from the current 18 mm and 21 mm to a larger size, and our height from 65 mm and 70 mm to a higher size, and then our capacity will also get a greater breakthrough.
After making the battery larger, the benefits it brings are obvious. First, it can increase the energy density of single cells, secondly, it can significantly reduce the cost of battery manufacturing, and then, it can also reduce the difficulty of power management.
However, when the battery is enlarged, it will also bring some new challenges to battery design and manufacturing process. For example, in product design, after the battery is enlarged, we must consider how to increase the capacity inside the battery.
In 2020, Tesla released a large cylindrical battery with a diameter of 46 mm and a height of 80 mm. Compared with the 21700 battery, its capacity has increased by 5 times, its capacity density has increased by 16%, and its power has increased by 6 times. It can be said that the performance of all aspects has been comprehensively improved.
From the current domestic situation, large cylindrical batteries can be roughly divided into two categories. One is the large cylindrical battery of ternary lithium, and the main application scenario is automotive power. At present, basically domestic and foreign manufacturers have adopted the same strategy as Tesla for such a battery and size of ternary power, which are all 46 mm, and the height ranges from 80 mm to 120 mm. This is to meet the height of different chassis from sedans to engineering vehicles. Then the shell material is made of steel.
In addition to the ternary system, the other one is probably the lithium iron phosphate system battery. After sorting out the information of various companies, we found that the specifications and sizes of the lithium iron phosphate system are relatively messy. From its diameter, it ranges from 32 mm to the largest 64 mm, and the height is mostly concentrated above 130 mm. Its main application scenarios are mainly small power and small energy storage. The shell material has both steel shell and aluminum shell. For lithium iron batteries, everyone pursues the same goal. The first is the ultimate cost-effectiveness, and the second is a relatively long cycle life.
The manufacturing process route of large cylindrical batteries is quite complicated. There are different processes to choose from in almost every process. If you want to develop a large cylindrical battery, you must finally determine two things. One is how big the battery should be, and the second is what kind of process route to take.
In addition, the compatibility of downstream end-user PACK, the compatibility of production efficiency, and the compatibility of the entire cost target must also be considered.
