1. What exactly is a soft pack battery?
Lithium batteries can be categorized into cylindrical, square and soft pack according to the encapsulation form. Cylindrical and square batteries are encapsulated with steel and aluminum shells respectively, while polymer soft pack lithium batteries are made of aluminum-plastic film wrapped with gel polymer electrolyte, which has the characteristics of ultra-thinness, high safety and so on, and can be made into batteries of any shapes and capacities. Moreover, once there is a problem inside the soft pack battery, the soft pack battery will bulge and open up from the weakest part of the battery surface, and will not produce a violent explosion, so its safety is relatively high.
2. The difference between soft pack and hard pack batteries
(1) Encapsulation structure: soft pack batteries are encapsulated with aluminum-plastic film packaging, while hard pack batteries use steel or aluminum shell encapsulation structure;
(2) Battery weight: thanks to the encapsulation structure of soft pack batteries, compared with the same capacity of hard pack batteries, the weight of soft pack batteries is lighter;
(3) Battery shape: hard-packed batteries have round and square shapes, while the shape of soft-packed batteries can be designed according to the actual needs, with higher flexibility in shape;
(4) Safety: compared with hard-packed batteries, soft-packed batteries have better venting performance, in extreme cases, soft-packed batteries will only bulge or crack at most, and will not have the risk of explosion like hard-packed batteries.
3. Advantages of soft pack battery
(1) Good safety performance: soft pack batteries in the structure of the aluminum-plastic film packaging, the occurrence of safety problems, soft pack batteries will generally only bulge and crack, unlike steel shell or aluminum shell battery cells may explode;
(2) High energy density: currently in the power battery industry, the average cell energy density of mass-produced ternary soft pack power batteries is 240-250Wh/kg, but the energy density of ternary square (hard shell) power batteries of the same material system is 210-230Wh/kg;
(3) Light weight: soft pack batteries are 40% lighter than steel shell lithium batteries of the same capacity, and 20% lighter than aluminum shell lithium batteries;
(4) Smaller battery internal resistance: ternary soft pack power battery can greatly reduce the self-consumption of the battery due to its own smaller internal resistance, improve the battery multiplier performance, small heat production and longer cycle life;
(5) Flexible design: the shape can be changed to any shape, can be thinner, and can be customized according to customer's needs to develop new battery cell models.
4. Disadvantages of soft pack batteries
(1) Imperfect supply chain: compared with hard pack batteries, soft pack batteries are not popular in the domestic market, and some of the raw materials and production equipment procurement channels are still relatively single;
(2) Low grouping efficiency: due to the lack of structural strength of soft pack batteries, soft pack batteries are too soft when grouping, so it is necessary to install a lot of plastic brackets outside the cell to strengthen its strength, but this practice is a waste of space, and at the same time, the efficiency of the battery grouping is also relatively low;
(3) The core is difficult to make big: due to the limitations of the aluminum-plastic film, soft pack battery cell thickness can not be too big, so only in the length and width to make up for it, but too long and too wide core is very difficult to put into the battery pack, the length of the current soft pack battery cell to achieve the limit of 500-600mm has reached;
(4) Higher cost of soft pack batteries: at present, the domestic soft pack lithium batteries used in high-end aluminum-plastic film is still mostly dependent on imports, so the cost of soft pack batteries is relatively high.
Post time: Feb-27-2024