Cylindrical lithium batteries are classified into different systems, including lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, cobalt-manganese hybrid, and ternary materials. The casings are available in steel and polymer types, each with its own advantages. Currently, cylindrical lithium iron phosphate batteries with steel casings are the most common. These batteries offer advantages such as high capacity, high output voltage, good charge-discharge cycle performance, stable output voltage, high current discharge capability, stable electrochemical performance, safety, wide operating temperature range, and environmental friendliness. They are widely used in solar lighting, lawn lighting, backup power, power tools, and toy models.
Square lithium batteries typically refer to rectangular batteries with aluminum or steel casings. Square batteries are very common in China. So, what are the differences between cylindrical and square lithium batteries?
Comparison of cylindrical and prismatic lithium batteries
1. Battery shape: Square batteries can be designed in any size, while cylindrical batteries cannot.
2. Rate characteristics: Due to the limitations of the welding process for multiple tabs in cylindrical batteries, the rate characteristics are slightly worse than those of square multi-tab batteries.
3. Discharge platform: Lithium batteries using the same positive and negative electrode materials and electrolytes should theoretically have the same discharge platform, but the discharge platform of square lithium batteries is slightly higher.
4. Product quality: The manufacturing process of cylindrical batteries is relatively mature, the probability of secondary cutting defects in the electrode sheets is low, and the winding process is mature and highly automated. The stacking process is still carried out in a semi-manual manner, which has an adverse effect on battery quality.
5. Electrode welding: Cylindrical battery electrodes are easier to weld than square lithium battery electrodes; square lithium battery electrodes are prone to poor welding, which affects battery quality.
6. Pack assembly: Cylindrical batteries are easier to use, so the packing technology is simple and the heat dissipation is good; when packing square lithium batteries, the heat dissipation problem must be solved.
7. Structural characteristics: The chemical activity at the corners of square lithium batteries is relatively poor, and the energy density of the battery is prone to decay with long-term use, resulting in a shorter battery life.
With the rise of automotive power batteries in recent years, the contradiction between vehicle range and battery capacity has become increasingly prominent. Domestic power battery manufacturers mostly use aluminum-cased square batteries with higher energy density because the structure of square batteries is relatively simple. Unlike cylindrical batteries, which use high-strength stainless steel as the casing and accessories such as explosion-proof safety valves, square batteries are lighter in weight and have relatively higher energy density.
