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Mar 16 , 2022
At present, there are three main packaging forms of lithium battery, namely cylindrical, prismatic and soft package.
Lithium prismatic battery usually refers to aluminum shell or steel shell prismatic battery. The popularity of prismatic batteries is high. The structure of the prismatic battery is relatively simple, unlike the cylindrical lithium-ion cell with high strength of stainless steel as its shell and explosion-proof safety valve accessories, so the overall accessory is light in weight and high in energy density.
1. The main components of a typical lithium prismatic battery include: a laminated plate or winding composed of cap plate cover, shell, positive plate, negative plate, and diaphragm, as well as insulation parts and safety components.
Among them, two in the red circle are safety structures: NSD needling safety device and OSD overcharge protection device.
2. Needling safety protection device
This is a lithium prismatic battery with a metal layer, such as a copper sheet, on the outside of the coil.
When needling occurs, the local large current generated at the needling position rapidly reduces the current per unit through a large area of copper sheets, which can prevent local overheating at the needling position and slow down thermal runaway of lithium battery.
3. Overcharge safety protection device
This safety design can now be found on many lithium prismatic batteries.
The device is typically a sheet metal used in conjunction with a fuse. Fuse can be designed on the positive current collector. When overcharging, the pressure generated inside the lithium battery causes the OSD to trigger an internal short circuit, resulting in a large instantaneous current, which fuses fuse and cuts off the battery’s internal current loop.
The shell of a lithium prismatic battery is usually a steel shell or aluminum one. With the market's pursuit of energy density and the progress of production technology, the aluminum shell has generally become the mainstream.
Lithium prismatic battery has high packaging reliability, high energy efficiency, relatively lightweight, high energy density, simple structure, and relatively convenient expansion, which is an important option to improve energy density by improving the capacity of the single cell.
Thanks to its large single-cell capacity, the system structure is relatively simple, which makes it possible to monitor the single-cell one by one. Another advantage brought by the simplicity of the lithium prismatic battery system is its relatively good stability.