Analysis of the Structure Characteristics and Technical Features of Cylindrical, Prismatic, and Pouch Lithium Batteries

Currently, lithium batteries come in three main packaging types: cylindrical, prismatic, and pouch. These different battery structures result in distinct characteristics, each with its advantages and disadvantages.

1. Cylindrical Lithium Batteries

Cylindrical lithium batteries, such as the 18650 model, were first invented by SONY in 1992 and quickly became a market leader. They are known for their mature manufacturing process, which uses a winding technique, high automation, and cost-effective production. These batteries are widely used in various devices, including electric vehicles (EVs).

With the growing demand for longer EV ranges, manufacturers have increasingly turned to larger cylindrical batteries, such as the 21700, which is now being mass-produced by Tesla and is expected to replace the 18650 in their vehicles.

2. Prismatic Lithium Batteries

Prismatic lithium batteries, often using aluminum or steel casings, are more commonly used in China, particularly in electric vehicles. Their structural simplicity and relatively high energy density make them popular, although they face challenges due to a wide range of models and non-standardized production processes.

For industrial applications that require multiple batteries in series or parallel, cylindrical batteries are often preferred due to their standardized manufacturing process.

3. Pouch Lithium Batteries

Pouch lithium batteries are distinct in their use of aluminum-plastic composite film as packaging material, which provides several advantages, such as light weight, better safety performance, and lower internal resistance. They are also highly customizable in terms of shape and size.

However, pouch batteries are more prone to leakage, and their production cost is higher than that of cylindrical and prismatic batteries. Despite these challenges, pouch batteries are becoming more popular in applications where lightweight, safety, and customization are priorities.

4. Technical Comparison

• Shape: Prismatic batteries can be customized in size, offering flexibility that cylindrical batteries cannot match.
• Rate Characteristics: Cylindrical batteries typically have a slightly lower rate capability compared to prismatic batteries.
• Discharge Platform: Although the discharge platforms are theoretically the same, prismatic batteries generally have a slight edge due to their lower internal resistance.
• Product Quality: Cylindrical batteries have a more mature manufacturing process, ensuring stable product quality, while prismatic batteries face quality variability due to less automated production.
• Welding of Terminals: Cylindrical batteries have easier and more reliable terminal welding compared to prismatic batteries.
• PACK Assembly: Cylindrical batteries are easier to assemble and have better heat dissipation, while prismatic batteries require careful thermal management during assembly.
• Structural Features: Prismatic batteries may experience performance degradation over time, particularly at the corners.

Conclusion

Cylindrical, prismatic, and pouch lithium batteries all have distinct strengths and weaknesses. As technology continues to evolve, these batteries will likely complement each other, providing efficient and safe energy solutions for a wide range of applications.