Square battery Square lithium battery usually refers to aluminum shell or steel shell square battery. The popularity rate of square battery is very high in China. With the rise of automobile power batteries in recent years, the contradiction between automobile mileage and battery capacity has become increasingly prominent. Domestic power Battery manufacturers mostly use aluminum-cased square batteries with higher battery energy density.
prismatic battery
Square lithium-ion batteries usually refer to aluminum-shell or steel-shell square batteries. The popularity of square batteries is very high in China. With the rise of automotive power lithium batteries in recent years, the contradiction between vehicle mileage and battery capacity has become increasingly prominent. Domestic power Lithium battery manufacturers mostly use aluminum-shell rectangular batteries with higher battery energy density. Because the structure of rectangular batteries is relatively simple, unlike cylindrical batteries, which use higher-strength stainless steel as casings and accessories such as explosion-proof safety valves, the overall Accessories should be light in weight and have a relatively high energy density. Square batteries use two different processes: winding and lamination.
Cylindrical battery
Cylindrical batteries are mainly steel-cased cylindrical lithium iron phosphate batteries. This kind of battery has high capacity, high output voltage, good charge and discharge cycle performance, stable output voltage, can discharge at large currents, stable electrochemical performance, and is easy to use. Safe, wide operating temperature range, environmentally friendly. Widely used in solar lamps, lawn lamps, backup energy, power tools, toy models.
The structure of a typical cylindrical battery includes: positive electrode cover, safety valve, PTC element, current cutoff mechanism, gasket, positive electrode, negative electrode, isolation film, and case.
Soft pack battery
Soft-pack batteries are liquid lithium-ion batteries covered with a polymer shell. The biggest difference from other batteries is the soft packaging material (aluminum-plastic composite film), which is also the most critical and technically difficult material in soft-pack lithium-ion batteries. . The packaging materials and structure of pouch batteries give them many advantages.
Differences in technical characteristics between square, cylindrical and soft packages
1. Battery shape: Square lithium-ion batteries can be of any size, while soft-pack batteries can be made thinner, which is incomparable to cylindrical batteries.
2. Rate characteristics: There are process limitations for welding multi-pole tabs in cylindrical lithium-ion batteries, so the rate characteristics are slightly worse than the square multi-pole tab method.
3. Discharge platform: The same positive electrode material, negative electrode material, and electrolyte are used, so the discharge platform is theoretically the same. However, the internal resistance of the square battery has a slight advantage, so the discharge platform is slightly higher.
4. Product quality: The cylindrical lithium-ion battery process is very mature, the probability of common secondary slitting defects of pole pieces is low, and the winding process is more mature and automated than the lamination process. The lamination process is still using a semi-manual method. , so there is a negative impact on the quality of the battery.
5. Welding of tabs: The tabs of cylindrical lithium-ion batteries are easier to weld than square lithium-ion batteries. Square batteries are prone to false welding, which affects battery quality.
6. PACK into groups: Circular batteries are relatively easier to use, so the PACK method is simple and the heat dissipation effect is good. When packing square batteries, the heat dissipation problem must be solved.
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