The structure difference between cylindrical lithium battery and square lithium battery
Cylindrical lithium batteries are divided into different systems of lithium iron phosphate, lithium cobalt oxide, lithium manganate, cobalt-manganese hybrid, and ternary materials. The outer shell is divided into two types: steel shell and polymer. Batteries with different material systems have different advantages. At present, the cylinders are mainly steel-shell cylindrical ferrophosphate batteries, which are characterized by high capacity, high output voltage, good charge and discharge cycle performance, stable output voltage, large current discharge, stable electrochemical performance, and use Safe, wide operating temperature range, and environmentally friendly. It is widely used in solar lamps, lawn lamps, back-up energy, power tools, toy models.
The structure of a typical cylindrical battery includes: a positive electrode cover, a safety valve, a PTC element, a current cut-off mechanism, a gasket, a positive electrode, a negative electrode, a separator, and a casing.
Square lithium battery usually refers to aluminum shell or steel shell square battery. The popularity 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. Battery manufacturers mostly use aluminum shell square batteries with higher battery energy density. Because the structure of square batteries is relatively simple, unlike cylindrical batteries, which use high-strength stainless steel as the shell and accessories such as explosion-proof safety valves, the overall accessories The weight should be light, and the relative energy density should be higher. Rectangular batteries use two different processes: winding and lamination.
Comparison of cylindrical lithium battery and square lithium battery
Battery shape: The square lithium battery can be of any size, so it is not comparable to a cylindrical battery.
Rate characteristics: the process limitation of cylindrical lithium battery welding multi-pole lugs, so the rate characteristics are slightly worse than square.
Using the same positive electrode material, negative electrode material, and electrolyte, the discharge platform is theoretically the same, but the internal resistance of the square battery is slightly superior, so the discharge platform is slightly higher.
Product quality: Cylindrical lithium battery technology is very mature, the probability of common secondary slitting defects of the pole piece is low, and the winding process is more mature and automated than the lamination process. The lamination process is currently still using semi-manual methods, so for The quality of the battery has an adverse effect.
Tab welding: The tabs of cylindrical lithium batteries are easier to weld than square lithium batteries, and square batteries are prone to false welding that affects battery quality.
PACK group: Cylindrical batteries are relatively easier to use, so the PACK scheme is simple and the heat dissipation effect is good. When the square battery packs, the heat dissipation problem must be solved.
Structural features: The chemical activity at the corners of the square lithium battery is poor, and the performance of the battery is significantly reduced after long-term use.
Post time: Jul-06-2021
