Prismatic Battery Cell VS Cylindrical Battery cell
Description
There is a lot of difference between Prismatic Battery Cell and Cylindrical Battery cell,let’s find it from structure and feature and performance,production,aspects etc.
1.Structure and Packaging
1.1.Prismaticbattery cell
The outer shell is usually made of materials such as aluminum alloy or stainless steel,with high structural strength,the top cover structure is complex,including a top cover plate, positive and negative poles,explosion-proof devices,injection holes,etc.the pole part has protective mechanisms such as flipping plate devices,current cutoff structures,and short-circuit devices,the core can be wound or laminated,and the laminated square shell battery cell has low internal resistance,good charging and discharging power performance,high energy density.
1.2.Cylindrical battery cell
The outer shell is generally made of steel or polymer,using winding technology,with high degree of automation and stable product quality,common models include 18650,21700, 26650,46800,etc.,which have standardized diameter and height dimensions and are universal standard electronic devices.
2.Performance characteristics
2.1.Energy density
Under the same volume,prismatic can accommodate more active substances,resulting in a relatively high energy density,for example,the prismatic energy density ratio calculated at 50AH can reach 205WH/Kg,with system rate of around 70%,energy density is approximately 143WH/Kg,the energy density of cylindrical relatively low,for example,the mainstream 18650 (1.75AH) energy density can reach 215WH/Kg,but system rate is around 60%,the energy density ratio of 18650 battery system is about 129WH/Kg.
2.2.Rate performance
Prismatic battery cell usually have good rate performance,the mainstream energy type cells manufactured domestically can reach around 1.5-2C in square shape (with good thermal management)with the improvement of manufacturing technology,it is possible to achieve the policy target of 3C,cylindrical battery cells are limited by the welding multipole ear process, resulting in slightly poorer rate characteristics,the mainstream charging and discharging rate of 18650 cylindrical battery cells in China is around 1C.
2.3.Cycle life
After 3000 cycles of 1C charging and 1C discharging,the best prismatic battery cell still has a remaining capacity of 90%,while the best 18650 cylindrical cell has a capacity of only 60%,the cycle life of square shell cells is better than that of cylindrical cells.
2.4.Consistency
Due to the large individual capacity of square shell cells, a small number of cells are required to form a battery pack,assuming that the defect rate of one cell is one in 100000,a prismatic cell battery pack consisting of 250 cells has a pass rate of 0.99999 * 245=99.7%,which is more conducive to controlling consistency. When cylindrical battery cells are used to form a battery pack,there are many battery cells. For example, a circular battery pack consisting of 7000 18650 cells has a pass rate of 0.99999 * 7000=93.2%, making consistency control difficult.
3.Manufacturing
3.1.Production process
The manufacturing process of prismatic battery cell is relatively complex, and the yield and consistency are relatively poor,the winding process of cylindrical battery cells is mature, with a high degree of automation,high production efficiency,and relatively low cost,however,the production process of large cylindrical battery cells such as 4680 batteries is difficult,and the initial production yield is relatively low.
4.Application
4.1.Prismatic battery cell
widely used in fields such as new energy vehicles and energy storage systems.in the field of new energy vehicles,it produced by companies such as CATL and BYD are widely used in models of brands such as Tesla and BYD.
4.2.Cylindrical cells
Traditional 18650 batteries have been widely used in electronic products and other fields,while small cylindrical cells such as 14500 and 16340 are mainly used in consumer electronics, such as wireless audio,electric toys,digital cameras,etc,large cylindrical battery cells such as the 4680 battery are also used in the field of electric vehicles,such as some Tesla models.
5.Heat dissipation and thermal management
5.1.Prismatic
The battery cell has a large capacity,few heat dissipation surfaces,poor heat dissipation performance,long internal heat transfer path,and difficult local heat dissipation,more effective heat dissipation design is needed to ensure temperature uniformity.
5.2.Cylindrical battery cell
The battery cell has a small capacity and multiple heat dissipation surfaces,but the effective contact heat transfer area is small,and the thermal management efficiency is in the middle. However,the gaps between cylindrical batteries facilitate heat dissipation within the battery pack.
6.Conclusion
Overall,Prismatic cell and cylindrical cell each have their own advantages and disadvantages,and they play their respective roles in different application,prismatic battery cells are widely used in fields such as new energy vehicles and energy storage systems that require high energy density,cycle life,and consistency;cylindrical battery cells have advantages in the field of consumer electronics and in cost sensitive scenarios that require high automation production.