Batteries, an indispensable part of our daily lives, come in various form factors. Multiple types are available, from the widely used cylindrical batteries to the thin and flat pouch-type batteries. These batteries differ not only in shape but also in their manufacturing processes, allowing users to select form factors based on their intended applications. In this infographic, we will explore the characteristics of cylindrical and pouch-type batteries.
Cylindrical Battery: The Classic Form Factor in the Industry
One of the most common battery shapes is the cylindrical battery, which features a round, cylinder-like design. Currently, standardized cylindrical batteries such as 18650 and 21700 are widely used, while the next-generation 46-series batteries are gaining attention. The numbers 18650 and 21700 indicate each battery’s dimensions: the 18650 battery measures 18mm in diameter and 65mm in height; the 21700 measures 21mm by 70mm; and the 46-series battery has a diameter of 46mm.
Cylindrical batteries are manufactured using a winding method, in which the materials are rolled up. A device called a winder is used to wind one roll each of anode material and cathode material, and two separator rolls onto a mandrel to create a “jelly roll.” Afterward, aluminum tabs are attached to the uncoated part of the cathode and copper tabs to the uncoated part of the anode, which are then welded. Following tab shaping, the jelly roll is inserted into a cylindrical battery can, and the tabs are welded to the top and bottom terminals. Finally, the can is vacuumed, electrolyte is injected, and the battery is sealed to complete the process.
What are the characteristics of cylindrical batteries? One advantage is their efficient mass production. As the oldest form factor, they benefit from well-established, standardized manufacturing facilities. Additionally, cylindrical batteries have a stable structure. The strong, thick can encases the internal structure, providing high stability and reliability. Lastly, as battery size increases, so does its energy storage capacity. Appropriate cylindrical battery models — 18650, 21700, and 46-series — are available depending on the application.
Pouch-Type Battery: Thin, Flat, and Efficient
Unlike cylindrical batteries, where materials are wound like a roll of paper towels, pouch-type batteries are constructed by stacking layers of materials and housing them in a flat pouch case. LG Energy Solution employs a proprietary “Lamination & Stacking” method to produce these batteries.
First, to insert the materials into the pouch case pocket, basic battery units called mono-cells are produced, where multiple electrodes and separators are combined. A mono-cell has a stacked structure in the sequence of separator–central electrode–separator–outer electrode. To achieve this, the cathode, anode, and separator are first aligned and bonded through the lamination process. Next, in the stacking process, mono-cells are repeatedly stacked, and finally, half-cells are stacked to create a “cell stack.”
Once the cell stack is completed, leads are welded onto it. The pouch film is compressed to form a case, into which the cell is inserted and assembled. Electrolyte is then injected through the gas pocket, ensuring it fully permeates the pores in the electrode pockets. Finally, the pouch is sealed, taking its final form as a pouch-type battery.
Pouch-type batteries offer several advantages due to their layered construction. The pouch case is made by compressing a film material, and the internal components are stacked in a way that minimizes density. This design allows for a thin and flat structure that can accommodate more cells, thereby increasing energy density relative to volume. Additionally, the use of an aluminum film pouch significantly reduces the battery’s weight. Lastly, pouch-type batteries can be customized in size and shape according to customer needs and the specific applications in which they will be used.
Through this comparison of cylindrical and pouch-type batteries, we can see that while they differ in manufacturing processes and design, each has its own unique strengths. Stay tuned for more engaging and easy-to-understand battery insights in future infographics!
