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CATL Kirin battery structure design analysis

• 2023-12-07

 CATL Kirin battery structure 

Recently, I saw the video of the first dismantling of the Kirin battery on the website, although the video introduces the structural design of the Kirin battery relatively little, but you can learn some details from the video screen.

First of all, let's take a look at the appearance of the battery, there is no big difference from the conventional design, 6 pieces of thick buffer foam are set on the upper cover of the battery pack, two pressure relief valves are set at the front end, and 4 pressure relief valves can be seen at the rear end, so the entire battery pack is set up with a total of 6 pressure relief valves.

After opening the battery pack, you can see the electrical structure inside the battery pack, a total of six rows of battery cell design, water cooling pipes are arranged on both sides of the battery pack, but I was surprised to find that the battery cell part does not have any horizontal longitudinal beams, which is different from the Kirin battery when it was released. The high-voltage part is arranged at the front end of the battery pack, and the middle is separated from the battery part by a beam, and the high-voltage part can be seen to be cooled separately by a water cooling plate at the back.

The battery cell is obviously placed upwards normally, and the CCS part is connected to the busbar by means of FPC+NTC nickel sheet welding, and the wiring harness isolation plate is used, and the hot-pressed CCS is not used, which is also a bit interesting. The surface of the busbar is covered with a layer of thermal protective insulating material.

In addition, there is also a detail that the top edge of each row of cells is reinforced with FR4 materials (yellow strips in the picture), which should be to increase the overall structural strength, and the top patch of the cells is short, and does not cover the position where FR4 needs to be bonded.

After removing the busbar, FPC, isolation plate, and thermal insulation materials, you can see all the cells and the water cooling plate between the cells. Moreover, some foam-like materials are played in the groove composed of cells, cold plates and cells, which is probably to improve the buffering capacity between the cells. Judging from the action of disassembling the cell, it is quite easy, the double-sided tape should be used between the cell and the water cooling plate, and the water cooling plate itself should be insulated by powder spraying

It can be further seen that the pressure relief valve of the battery cell is arranged at the bottom of the cell, and there is no PC top patch at the bottom, mainly so that the cell body on both sides of the bottom can be directly bonded with the structural adhesive to improve the structural strength, and at the same time, the bottom is set up with a rubber blocking mechanism for the structural adhesive to avoid the structural adhesive overflowing to the pressure relief valve, and the position of the shoulder to shoulder of the cell is provided with a heat insulation material to block the only channel of thermal runaway between the cells. The pressure relief valve is provided with a pressure relief and smoke exhaust hole in the opposite position, and a mica plate is arranged between the outside of the lower shell of the battery pack and the bottom guard plate for thermal runaway protection.

In generally, the design of the Kirin battery is still innovative, and it feels like it draws on Tesla's design ideas in general, especially the filling of foam materials between the cells, the setting of mica at the bottom, the cooling between the cells, etc., all have similarities, this is the first mass production version of the Kirin battery, and Ningde will definitely further optimize and improve the design in the future, and there may also be new solutions.

 

-Summarized by JADE 2023