Lithium Battery Safety Test Revealed

In recent years, frequent fire accidents in the fields of electric vehicles and energy storage have led to large-scale recalls, and the main body of responsibility has spread to domestic and foreign manufacturers and battery companies. Not only the brand image of the company involved is damaged, but the battery company is also required to bear the huge cost of recalling or replacing the battery.

Judging from the disclosed causes of safety accidents, the quality defect of lithium batteries is one of the key factors causing the above-mentioned safety hazards. More and more battery companies have tasted the bitter fruit caused by battery production defects, and some even suffered a devastating blow. The painful history has sounded the safety alarm for all battery companies.

Especially in the new cycle of large-scale expansion of power batteries, battery companies have increasingly stringent requirements for high-quality control and safety in the production process. As an important level of battery safety, the importance of lithium battery testing equipment is self-evident.

Safety can not be ignored

Gaogong Lithium Battery has learned that in the die-cutting and lamination process, electrode piece burrs and dust will not only reduce the energy density of the battery, but more importantly, once the battery separator is broken down, it will directly cause self-discharge or internal short circuit of the battery, which will seriously lead to potential safety hazards. . Therefore, how to control the burr size during punching, reduce the dust generated by punching, and avoid the generation of burrs during the pole piece transfer process has become the biggest problem faced by the above two core processes.

However, in the field of pole piece burr detection, vision microscopes are commonly used, which have such pain points as insufficient depth of field, insufficient magnification, some without measurement function, cumbersome operation, and some without measurement function, unable to measure 3D data, etc., in order to meet customer needs Some even require multiple machines to meet the demand, which cannot meet the stringent requirements of battery companies for burr detection and high-efficiency manufacturing goals.

In the pole piece burr detection process, some visual microscopes cannot see the whole picture clearly due to insufficient depth of field, but can only see the part clearly. The disadvantage is that the 7μm data may be measured as 3μm in actual measurement, and there is a greater safety risk.

The emergence of Keyence's digital microscope system not only solves many pain points of visual microscopes, but also makes it more convenient for battery companies to use in actual observation, shooting and measurement, which assists the large-scale manufacturing and safety testing of power batteries. Large-scale introduction and rapid penetration in the field of chip detection.

For the detection requirements of whether the pole piece has burrs and whether the length is within the specification, VHX series digital microscopes are realized by two major detection methods: single-piece movement detection of large platform fixture and winding multi-layer large-scale detection.

(Left: VHX series fixture single-piece vertical section burr detection; Right: VHX series winding multi-layer large-scale burr detection.)

Specifically, the VHX series first uses 100x magnification to check the field of view of the pole piece with a length of about 3.5mm. Once an abnormality is found, it is further switched to 300x, 500x, and 800x magnification for burr determination and measurement.

(The comparison diagram of the left 100 magnification pole piece inspection and the right 500 magnification pole piece inspection.)

When observing at high magnification, it is inevitable that the depth of field problem will occur, and the surface of the sample with concave and convex cannot be seen clearly. Conventional products usually need to be adjusted to focus. The VHX series only needs a simple button to realize the clear highlight of the full-frame focus and quickly see the surface.

(VHX series full-frame focus image (above) compared to other microscope renderings (below).)

At the same time, the VHX series has the function of reproducing shooting. When the standard shooting conditions are reached, the operator simply clicks the standard picture to automatically shoot the standard effect, which is less dependent on the user and the maturity of use. Therefore, the VHX series has extremely high definition and excellent operability.