Lithium-ion batteries are rechargeable batteries that primarily function by the movement of lithium ions between the positive and negative electrodes. There are three main types of lithium-ion battery packaging: cylindrical, prismatic, and pouch. Each packaging structure has different characteristics, advantages, and disadvantages.
1. Cylindrical lithium-ion battery
Cylindrical lithium batteries are classified into lithium iron phosphate batteries, lithium cobalt oxide batteries, lithium phosphate batteries, cobalt manganese batteries, and three-dimensional materials. Currently, the main performance characteristics of Li-Fe-P batteries are large size, high output voltage, good charging cycles, stable output voltage, large charge/discharge current, stable photocatalytic performance, high operating temperature, and environmental friendliness. They are widely used in solar lights, lawn lights, power storage, pneumatic tools, toy models, etc.
A typical cylindrical rechargeable battery consists of a cap, valve, PTC assembly, open current, sealing ring, positive phase, negative phase, protective film, and casing.
In 1991, Sony of Japan invented the first cylindrical lithium-ion battery. Due to its long history, the 18650 cylindrical lithium battery enjoys high market coverage. Cylindrical lithium batteries come in many specifications, such as 14650, 17490, 18650, 21700, and 26650. Cylindrical lithium-ion batteries are very popular in Japan and abroad.
2. Square lithium-ion battery
Square lithium batteries generally refer to aluminum-cased or steel-cased square batteries, and their market penetration in China is very high. In recent years, with the increasing popularity of lithium-ion batteries for automotive power, the difference between range and battery power has become increasingly apparent. Most Chinese power lithium battery manufacturers choose high-energy rechargeable aluminum-cased square batteries because of their simple structure. Unlike stainless steel plates with high pressure resistance for explosion-proof valve bodies, square batteries are lighter and have higher performance. Square rechargeable batteries are manufactured using two different processes: back-wiring and winding.
However, because prismatic lithium batteries can be customized to production specifications, there are many types available on the market. However, due to the large size of these batteries, standardization of processing technology is difficult. While the application of prismatic batteries in general electronic devices is not a problem, for various serial and series-connected mechanical equipment products, it is best to use standardized cylindrical lithium batteries to ensure smooth production processes and make it easier to find replaceable rechargeable batteries.
3. Soft-pack lithium-ion battery
Hard-pack lithium batteries are polymer sleeves used in liquid lithium batteries. The difference between hard-pack lithium batteries and other rechargeable batteries lies in the plastic soft-pack material (plastic composite pack). Plastic soft-pack materials generally consist of three layers: an outer barrier layer (usually a surface protective layer made of polyester or polyester), a permeable layer (inner platinum), and an inner layer (intelligent high-resistance layer).
The packaging and structure of pouch batteries give them the following advantages:
(1) Good safety factor: The structure of soft-pack batteries is aluminum-plastic film. Under safety risk, the maximum number of soft-pack batteries will be destroyed, rather than exploding like lithium ions in aluminum shells.
(2) Lightweight: The net weight of the soft-coated battery is 40% lighter than that of a lithium battery with an aluminum shell of the same size, and 20% lighter than that of a rechargeable battery with an aluminum shell.
(3) Large capacity: Compared with aluminum-cased batteries of the same type, soft-pack batteries have a capacity of 1015% and 510% higher than aluminum-cased batteries.
(4) Low internal resistance: The internal resistance of soft-sealed batteries is relatively low. Currently, the internal resistance of soft-sealed battery cells can be guaranteed to be at least 35m.
(5) Intelligent design scheme: The appearance of the soft-sealed battery can be customized according to customer requirements, and lithium-ion model specifications can be developed.
The current of soft-pack lithium batteries is limited, and the number of models and specifications of soft-pack battery cells cannot meet market demand;
4. Comparative Analysis of Three Packaging Forms for Lithium-ion Batteries
Appearance of rechargeable batteries: Square lithium batteries can be any size, so the battery inside the battery.
Multiple performance characteristics: The processing technology for welding multi-tabs in cylindrical lithium-ion batteries is limited, therefore the multi-tab design is slightly inferior to the square-shaped dot design.
Charge and discharge service platform: The same battery cathode material, lithium battery electrolyte are theoretically consistent, but square batteries have a slight upper resistance, so the charge and discharge service platform is slightly higher.
Product quality: The processing technology of cylindrical lithium batteries is well-developed, the probability of defects in the second part is low, and the quality indicators and automation technology level must be higher than those of rotary presses.
Ear tab welding: The tabs of cylindrical lithium batteries are easier to weld than those of square lithium batteries, which are easier to weld.
Combination: The relevance of ring-shaped rechargeable batteries is more practical, so the combination method is simple and effective, and the square battery handles the heat removal problem.
Structural characteristics: Square-shaped batteries have weaker organic chemical specificity, and their performance decreases significantly with long-term use.
Generally, the advantages and disadvantages of the three types of rechargeable batteries are cylindrical, prismatic, and hard-pack. Each battery has its own core components. For example, soft-pack batteries contain more prismatic lithium phosphate batteries and more than three elements. With the introduction of new automatic patching technology, the system software ratio of rechargeable batteries can become a key standard.
