What is the difference between the square, cylindrical and soft packs of lithium iron phosphate lifepo4 batteries? Many people probably know that there are many types of packaging for lithium iron batteries, namely cylindrical, square and soft packs. Different packaging structures mean different characteristics, and they have their own advantages and disadvantages. Let's discuss the differences between these three kinds of lifepo4 batteries!
Square lifepo4 battery
Square lifepo4 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. Domestic power battery manufacturers Aluminum shell prismatic batteries with higher battery energy density are mainly used. Because the structure of prismatic batteries is relatively simple, unlike cylindrical batteries that use stronger stainless steel as the shell and accessories such as explosion-proof safety valves, the weight of the overall accessories is required. Light, relatively high energy density. Square batteries have two different processes: winding and lamination.
Cylindrical lifepo4 battery
Cylindrical batteries are mainly steel-shell cylindrical lithium iron phosphate 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 safe use , Wide operating temperature range, 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.
Soft pack lifepo4 battery
The soft pack battery is a liquid lithium battery 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 the soft pack lithium battery. The packaging material and structure of the soft pack battery give it many advantages.
The advantages and disadvantages of the square, cylindrical and soft packs of lithium iron batteries
Cylindrical lithium battery pack.jpg
●Cylindrical Lithium Iron lifepo4 Battery
Advantages: Cylindrical lithium iron batteries are the earliest mature industrialized lithium battery products. After more than 20 years of development, the production process of cylindrical lithium batteries is now mature, with high production efficiency and relatively low cost, so the cost of PACK is also Relatively low, the yield of lithium batteries is higher than that of square lithium batteries and soft-packed lithium batteries, and their consistency and safety are also excellent.
Disadvantages: Because the cylindrical iron-lithium battery is generally packaged in a steel shell, although the safety is relatively high, the weight will also be heavier, which will also make the specific energy of the lithium battery pack relatively low.
●Rectangular lithium iron lifepo4 battery
Advantages: The packaging shells of square iron-lithium batteries are mostly made of aluminum alloy and stainless steel. The inside of the battery adopts winding or laminated technology, which protects the battery cell better than soft-packed lithium battery. The safety of the battery cell Compared with the cylindrical lithium battery, there is also a big improvement.
Disadvantages: The square lithium iron battery pack can be customized according to the size of the product, but it will also cause many different types of square lithium batteries on the market. Too many different types of lithium batteries will make it difficult to unify the process, making the automation level not high, the monomers are quite different, and there may also be groups of square lithium battery packs that are far below the life of a single lithium battery.
●Soft pack iron lithium lifepo4 battery
Advantages: The soft-packed lithium iron battery uses polymer electrolyte and soft packaging materials, which are the most critical and technically difficult materials in the soft-packed lithium battery. The soft packaging material means that the soft pack lithium battery can also be customized according to the requirements of customers. Soft pack lithium batteries are not explosive like square lithium batteries and cylindrical lithium batteries, and they are lighter than other batteries.
Disadvantages: Although the shape of the soft-packed iron-lithium battery can be customized according to the needs of customers, the existing soft-packed batteries have fewer models, which cannot meet the needs of the market, and the cost of developing new models is relatively high. In addition to the high development cost, the material cost of soft-pack lithium batteries is higher than that of cylindrical and square batteries. The cost issue is the focus of soft-pack lithium battery companies that need to make breakthroughs in the future.
Square, cylindrical and soft package technical characteristics difference
1. Battery shape: square lithium batteries can be of any size, while soft pack batteries can be made thinner, which is incomparable to cylindrical batteries.
2. Rate characteristics: Cylindrical lithium battery welding multi-electrode is limited by the process, so the rate characteristics are slightly inferior to the square multi-electrode solution.
3. Discharge platform: The same cathode material, anode material, and electrolyte are used, so theoretically the discharge platform is the same, but the internal resistance of the square battery is slightly dominant, so the discharge platform is slightly higher.
4. 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. Therefore, there is an adverse effect on the quality of the battery.
5. Tab welding: Cylindrical lithium battery tabs are easier to weld than square lithium batteries, and square batteries are prone to false welding that affects battery quality.
6. PACK group: Round batteries are relatively easier to use, so the PACK scheme is simple and the heat dissipation effect is good. The heat dissipation problem must be solved when the square batteries are PACK.
7. Structural features: The chemical activity at the corners of the square battery is poor, and the performance of the battery is significantly reduced after long-term use.
In short, regardless of square, cylindrical and soft pack batteries, the reason why they can develop rapidly at present is because they have been well applied in their respective fields of application.
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