Compared with cylindrical lithium battery and soft pack lithium battery, which power lithium battery

At present, lithium-ion batteries are mainly square lithium battery, cylindrical lithium battery, and soft pack lithium battery three categories, of which square and cylindrical shells are important aluminum alloy, stainless steel, and other hard shells, while the shell of the soft pack is made of aluminum-plastic film, which is their essential difference, as shown in Table 1, the performance of soft pack lithium-ion batteries important advantages include:

1, good safety performance: the soft-pack battery electrolyte less leakage, and in the case of safety hazards, the soft-pack battery will blow open, unlike the hard-shell battery as the internal pressure will explode;

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

3, large battery capacity: soft bag saving volume 20%, higher than the steel shell battery capacity of the same size 50%, higher than the aluminum shell battery 20-30%;

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

5, small internal resistance: the internal resistance of the soft pack battery is smaller than that of the lithium-ion battery, and the minimum domestic can be 35m or less, which greatly reduces the battery power consumption;

6, flexible design: can be customized according to customer needs, can be thinner, ordinary aluminum shell can only do 4mm, soft bag can do 0.5mm.

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

1, soft pack batteries are more suitable for portable, high space or thickness requirements of the application field, such as 3C consumer electronics;

2, although the single capacity of the square battery is high, but it is heavy and large, and the soft pack battery has obvious advantages in terms of energy density, and the current single cell is also developing in the direction of large capacity and high rate, which will be more in line with the requirements of mobile power in fields such as new energy vehicles;

3. Although the production process of cylindrical batteries is mature and the energy density advantages are obvious, due to the small capacity of the single cell, the battery Pack of the same capacity requires more cells, such as the battery Pack capacity of Tesla ModelS is 85kWh, and there are about 7,000 18650 cylindrical batteries. These is very high requirements for the battery management system BMS, and the single capacity of the soft Pack battery can be up to more than 10 18650 cylindrical batteries, the requirements for BMS are low, between the domestic and even most of the world's BMS supporting capacity is limited, the large-capacity battery pack will not use too many cylindrical batteries, in addition, cylindrical batteries due to high energy density lead to poor safety, And the hard shell leads to large internal pressure, and often explosive events occur, while the soft-pack battery has obvious advantages.

In summary, the advantages and disadvantages of the soft-pack battery almost go hand in hand, because the shape of the soft-pack battery is flexibly designed according to the needs of customers, and the battery cell is also remade, so the number of the existing soft-pack battery is too small for a unified model, and the cost of developing a new soft-pack battery pack is also very high.