LiPo cell and 18650 cell are both lithium-ion cells. So what’s the difference between them? Which cell is better? This article will introduce the similarities and differences between LiPo cell and 18650 cell in battery structure, cycle life, safety, etc.
Part 1. Lipo battery cell
- Construction: LiPo cells typically feature a flexible pouch or foil packaging, allowing for a lightweight and compact design.
- Chemistry: LiPo cells use a polymer electrolyte, which offers high energy density and allows for a greater range of shapes and sizes.
- Applications: LiPo cells are commonly used in applications requiring high discharge rates, such as remote-controlled vehicles, drones, and portable electronics.
Lithium-ion cells are divided into liquid lithium-ion cells and lipo cells. As for which of the two cells is more stable, it cannot be generalized. It mainly depends on the battery manufacturer’s technical level.
Lipo cells generally use soft aluminum-plastic composite packaging film. Its interior is a semi-solid polymer. The lipo cell discharges smoothly and has high efficiency and small internal resistance. The lipo cell has good safety performance and has over-current and over-voltage protection devices. The Lipo cell has a service life of approximately 500 charge and discharge cycles.
In terms of shape, lipo cell has ultra-thin features. It can be made into batteries of any shape and capacity to meet the needs of various products. The minimum thickness that a lipo cell can achieve is up to 0.5mm. The nominal voltage of the lipo cell is the same as the Li-ion battery, which is also a nominal voltage of 3.7V. And lipo cell has no memory effect.
As mentioned, lipo cells are usually packaged in tin foil, making the battery easily deformed and not resistant to impact. Moreover, the quality of lipo cells varies due to the overvoltage protection of different battery manufacturers.
Part 2.18650 cell
- Construction: 18650 cells are cylindrical, with a standard diameter of 18 millimeters and a length of 65 millimeters.
- Chemistry: 18650 cells use a liquid electrolyte and are typically composed of a metal casing housing the cathode, anode, and electrolyte.
- Applications: 18650 cells are widely used in applications such as laptops, flashlights, power tools, and electric vehicles, where their cylindrical form factor and high energy density are advantageous.
18650 cell is an improved product of lithium battery. After years of development, the technology of 18650 cells has become relatively mature. High-volume production has made its manufacturing costs very low. Therefore, the 18650 cell has a price advantage over the Lipo cell.
18650 cell occupies most of the lithium battery market share. 18650 cell is the most common in laptop batteries. The 18650 cell with steel shell has a high safety factor, and the production technology is very mature. And the price is lower than that of a LiPO cell.
Part 3. 18650 vs Lipo：What is the difference between a lipo and an 18650 cell?
1. Cycle life
The standard 18650 type A cell has a cycle life of about 500 times. Even the cycle life of a specially improved 18650 cell does not exceed 800 times. The Lipo cell can be charged and discharged more than 800 times. Some good quality lipo cells can be charged and discharged up to 1,200 times.
2. Convenience
The portability of a battery mainly refers to two aspects, namely weight and volume.
Both of these points are inseparable from battery energy density. Before comparison, it is necessary to distinguish between a single cell’s energy density and a battery pack’s energy density.
Regarding the energy density of a single cell, the 18650 cell is higher than the lipo cell. At the battery pack level, the energy density of the two is almost the same. However, lipo cells can make products appear thinner and have more diverse appearances.
3. safety
Compared with the 18650 cells, the lipo cell is thinner and more beautiful. However, lipo cells have not actually received much improvement in terms of safety.
Distinguish between cylindrical 18650 cells and lipo cells in terms of shape. Lipo cells are far from mature, and even lipo cells are not uniform in size, size, pole position, etc.
The production processes possessed by many battery manufacturers cannot meet the production conditions of lipo cells. Most battery manufacturers still rely on human control to produce lipo cells. The consistency of lipo cells cannot reach the level of 18650 cells. On the contrary, the 18650 cell adopts a steel shell design, safer than the lipo cell, whose production technology is not yet mature.
Part 4. Why do lipo cell and 18650 cell explode?
Many people are concerned about the problem of lithium battery explosions when using lithium batteries. During normal use of lithium batteries, the 18650 cells that explode are generally inferior. The safety of regular lithium batteries is quite good.
The main reason that lithium battery explosions can occur is that cells of poor quality are prone to internal short circuits during use. When an internal short circuit occurs, high-temperature and high-pressure gas will be generated in a short period. The lithium battery will explode when it is too late to be released through the exhaust valve.
In terms of battery safety, the performance of lipo cells is still very good. Lipo cells release gas more easily than batteries with metal shells. And even if the lipo cell explodes, the power will be much smaller.
Part 5. How to use the lipo cell and 18650 cell correctly?
In addition to buying high-quality lipo cells and 18650 cells to increase the use time of electrical equipment, consumers should also learn to use lipo cells and 18650 cells correctly.
When using lithium batteries, you should avoid the following common mistakes:
- Lithium batteries have no memory, and new lithium batteries do not need to be activated;
- Keep away from high temperatures. Lithium batteries are not sensitive to temperatures in the range of 0-40°C. However, once the temperature exceeds this range, the life and capacity of the lithium battery will be compromised. Excessive temperature will seriously shorten the life of lithium batteries;
- Avoid low temperatures. Low temperature will cause the lithium ions nested on the negative electrode of the cell to produce ion crystals, which will directly pierce the separator. A slight short circuit in the cell will affect the life and performance of the lithium battery.
- Lithium batteries should not be charged or discharged deeply. In other words, do not use lithium batteries to 0% before charging. When the cell voltage is lower than 2.4V, the materials inside the battery will be carbonized. This will accelerate the decline of cell capacity and service life. In severe cases, the lithium battery may be scrapped. This phenomenon is often referred to as battery over-discharge. The power of lithium batteries is best controlled in the range of 20-80%. Lithium batteries should be charged immediately when they are low on power.
In summary, while LiPo and 18650 cells are types of lithium-ion batteries, they differ in their packaging, electrolyte type, and applications. LiPo cells offer flexibility in shape and size and are suitable for high discharge applications. In contrast, 18650 cells are cylindrical and commonly used in a wide range of electronic devices and vehicles.
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