The soft-pack lithium battery is simply a liquid lithium-ion battery with a polymer shell. The structure is packaged in aluminum plastic film, and in the case of a safety hazard, the soft pack battery will only burst at most.
Soft pack lithium battery battery parameters
Nominal voltage: 3.7V
Working voltage: 2.4~4.2V
Nominal capacity: 1250mAh
Standard discharge continuous current: 0.2C
Maximum discharge continuous current: 0.5C
Working temperature: Charging: 0~45°C
Product size: MAX9.5*35*52mm
Finished product internal resistance: ≤150mΩ
Lead type: GB1007/24#, line length 55mm protection parameters: overcharge protection voltage/ 4.325±0.025V per string
Over-discharge protection voltage 2.5±0.05V
Overcurrent value: 2~4A
Lithium battery tab connection method
1. Drill the upper screw after tapping.
Advantages: high mechanical connection strength, firm and reliable, low cost.
Disadvantages: There is a certain risk due to the unknown thickness.
2. After drilling and tapping, use ordinary solder to solder copper wire and test with aluminum block. Step: Punch the work wire with tin wire to fill the middle. Don't forget the copper wire and copper wire 1.0 can not pull down the copper wire. For the sake of insurance, a pole is preferably two to three empty and then the copper belt is quite strong.
Advantages: Simple equipment, easy operation and low cost.
Disadvantages: Whether the welding is firm or not remains to be tested.
3. Direct welding with M51 welding wire (low temperature welding wire), welding material: M51+M51-F, low temperature copper and aluminum welding. M51 is the abbreviation of WEWELDING-M51, also called Universal 51. It is the grade of the American R&D Industrial Company. It is a low-temperature copper-aluminum welding wire with special rare elements. It was introduced by Weiouding (Tianjin) Welding Technology Co., Ltd. in 2010. Mainland China is mainly used to solve the remarkable ability of almost all white metals at low temperatures. White metals include zinc (nearly solderable), copper-lead alloys, tin-lead alloys, aluminum and lead. M51 can also weld any of the above metals to any other metal such as copper, brass, steel, stainless steel or bronze. Ma Yun home search, the price is a little expensive, the diameter of 1.3 mm 3 m long M51 will be 25 yuan, M51-F flux a small bottle will be 50 yuan.
Advantages: The introduction says that the equipment is simple and the welding is firm.
Disadvantages: high cost, whether it is firm or not to be tested
Soft pack lithium battery structure
The key materials used in soft-pack lithium batteries—positive materials, anode materials, and separators—have little difference from traditional steel and aluminum-shell lithium batteries. The biggest difference is the flexible packaging material (aluminum-plastic composite film). It is the most critical and technically difficult material in soft-pack lithium batteries. The flexible packaging material is usually divided into three layers, namely an outer resist layer (generally an outer protective layer composed of nylon BOPA or PET), a barrier layer (intermediate aluminum foil) and an inner layer (multifunctional high barrier layer).
The packaging material and structure of the soft pack battery have a series of advantages. According to the electric public public number, for example, the safety performance is good. The soft pack battery is packaged in aluminum plastic film. When a safety problem occurs, the soft pack battery is generally It will blow out without exploding like a steel shell or aluminum shell; light weight, soft pack battery weight is 40% lighter than steel shell lithium battery of the same capacity, 20% lighter than aluminum shell lithium battery; internal resistance Small, soft pack battery internal resistance is smaller than lithium battery, can greatly reduce the battery's self-consumption; good cycle performance, soft pack battery cycle life is longer, 100 cycles of attenuation is 4% ~ 7% less than aluminum shell Flexible design, variable shape and any shape, can be thinner, can be customized according to customer needs, develop new battery models. The shortcomings of the soft pack battery are poor consistency, high cost, and easy liquid leakage. The high cost can be solved by large-scale production, and the leakage can be solved by improving the quality of the aluminum plastic film.
Soft lithium battery and aluminum shell battery difference
In areas with high consumption levels, such as Europe and the United States, the use of soft-pack lithium batteries has an advantage. In most developing countries, such as India and the Middle East, aluminum-shell batteries have obvious advantages. The application area is reflected in the high-end smartphone market with the largest application volume. The soft-pack lithium battery represented by Apple and the aluminum-shell battery represented by Samsung are used as examples. Among them, Samsung mobile phones generally use a large size of 4.8 inches, the average battery capacity is about 2700mAh, while the average battery capacity of Apple's mobile phones is around 1700mAh.
There are no technical barriers in the industry, and there are still many technical problems to be solved in soft-package lithium batteries. Especially in the battery cycle expansion index, most battery manufacturers still have not solved this problem. Aluminum shell battery manufacturing is more automated than soft-pack lithium batteries, thus reducing the impact of human factors on product consistency to a certain extent, while saving labor costs.
In terms of manufacturing cost, aluminum shell battery materials have been completely localized, while aluminum plastic film materials for soft-packed lithium batteries still need to be imported, and aluminum shell batteries have lower technical requirements for battery materials than soft-pack lithium batteries. Therefore, the overall material cost is about 10% lower than that of a soft-pack lithium battery at the same capacity. In addition, the finished product is simple, reliable and cost-effective.