Cylindrical lithium batteries are simply round lithium batteries. Here, we usually refer to cylindrical 18560 lithium batteries. Cylindrical lithium batteries are the most researched and analyzed battery type, and the most comprehensively discussed in technical terms. A single cylindrical lithium battery is mainly composed of a positive electrode, a negative electrode, a separator, positive and negative current collectors, valves, overcurrent protection devices, insulation components, and a casing. Early casings were mostly made of steel, but currently aluminum casings are the dominant type.
Cylindrical lithium batteries can be divided into lithium cobalt oxide batteries, lithium manganese oxide batteries, and ternary materials. Each of these three material systems has its own advantages, and these batteries are widely used in: laptops, digital cameras, lighting equipment, children's toys, pneumatic tools, portable mobile energy sources, and other fields.
Advantages of cylindrical lithium batteries:
1. Good individual consistency
In other words, it can also be mass-produced and manufactured. Battery manufacturers have mature and advanced technology, and their daily production capacity for cylindrical lithium batteries is high (for example, Liangneng Battery Manufacturer can produce and process 200,000 cylindrical lithium batteries per day).
2. Cylindrical lithium batteries are heat resistant, safe, and not prone to explosion.
Individual cylindrical batteries possess superior mechanical properties. Compared to square and pouch batteries, the closed cylinder offers the highest bending strength for similar dimensions; its superior sealing performance also reduces the risk of explosion. The technology is mature and low-cost, but the potential for further cost optimization in production has already been largely exhausted.
3. High energy density
Its small individual energy makes it easy to control in the event of a safety incident, but this very fact is also becoming a reason for its replacement (as the popular saying goes, what makes you great will also destroy you, and what doesn't kill you will make you strong; the same principle applies to everything).
4. Low internal resistance
This significantly reduces battery self-discharge, increases smartphone battery life, and can fully meet international standards. These polymer lithium batteries, compatible with high discharge currents, are also an ideal choice for remote control models, making them the most promising alternative to nickel-metal hydride batteries.
5. Wide range of applications
Laptops, walkie-talkies, portable disc players, instruments and meters, audio equipment, model airplanes, digital cameras, lighting equipment, children's toys, pneumatic tools, and other electronic devices—as an important part of the lithium battery family, 18650 batteries were widely used in consumer electronics in earlier years. In recent years, with the rapid rise of new energy electric vehicles, 18650 batteries have also begun to be used in the new energy electric vehicle industry.
Disadvantages of cylindrical lithium batteries:
1. Cylindrical lithium batteries have high-level individual system software.
In the context of new energy electric vehicles, the number of individual cylindrical batteries in the battery system software is very large, which greatly increases the complexity of the battery system software. Regardless of the structure or management system, the production cost of cylindrical batteries is higher than that of the other two types of batteries at the system software level.
2. The probability of characteristic variation in cylindrical lithium battery cells increases.
Under uneven operating temperature conditions, the probability of significant changes in the characteristics of a large number of battery cells increases. However, I believe that Tesla's initial choice of 18650 cells in its car design was simply a matter of necessity. This is because, ten years ago, the only qualified power batteries that could be mass-produced were cylindrical cells. The safety and thermal management requirements of the batteries, on the contrary, became the driving force behind the development of its powerful electronic control system.
3. The potential for further increases in energy density is already very limited.
The potential for further increases in energy density is already very limited. AWC achieved a single-cell capacity of 4050 mAh and a cell specific energy of 306 Wh/kg, and no higher records have been seen since. Within this limited space, only continuous optimization of materials can lead to better prospects.
