At present, there are three main types of lithium-ion batteries: square lithium batteries, cylindrical lithium batteries, and pouch cell lithium batteries.

Among them, the square and cylindrical shells are mainly made of hard shells such as aluminum alloy and stainless steel, while the shells of soft packs are made of Aluminum Laminated. The important advantages of soft pack lithium-ion batteries in terms of performance include the following:

1. Good safety performance: The Pouch Cell battery has less electrolyte leakage, and in the event of a safety hazard, the pouch cell battery will swell and crack, instead of exploding when the internal pressure is too high like a hard-shell battery;

2. Light weight: The weight of the soft pack battery is 40% lighter than that of the steel shell square battery of the same capacity, and 20% lighter than the aluminum shell square battery;

3. Large battery capacity: the pouch cell saves 20% of the volume, which is 50% higher than that of the steel shell battery of the same size and 20-30% higher than that of the aluminum shell battery;

4. Good cycle performance: the cycle life of the soft pack battery is longer, and the attenuation of 100 cycles is 4% to 7% less than that of the aluminum case;

5. Small internal resistance: The internal resistance of the pouch cell battery is smaller than that of the lithium-ion battery, and the minimum domestic resistance can be less than 35m, which greatly reduces the self-consumption of the battery;

6. Flexible design: the shape can be customized according to customer needs, and it can be made thinner. The ordinary aluminum shell can only be 4mm, and the soft bag can be 0.5mm.

In terms of performance, soft pack batteries have more comprehensive advantages, and have broad application prospects in the future:

1. pouch cell batteries are more suitable for portable applications that require high space or thickness, such as 3C consumer electronics;

2. Although the single cell capacity of the square battery is high, it is heavy and large, while the soft pack battery has obvious advantages in terms of energy density, and the single cell is also developing in the direction of large capacity and high rate.

It will be more in line with the requirements for mobile power in new energy vehicles and other fields;

3. Although the production process of cylindrical batteries is mature and the energy density advantage is obvious, due to the small capacity of the single cell, the battery pack of the same capacity requires more cells, which has very high requirements for the BMS(BMS tester) of the battery management system. The single capacity of the soft pack battery can reach more than 10 18650 type cylindrical batteries, and the requirements for BMS are lower.