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LUSTER: Solving the dilemma of Lithium Battery Inspection

Mar 01, 2022

The global lithium battery industry is undergoing profound changes, power battery performance, quality competition escalation has led to the acceleration of new equipment and new process iterations. According to GGII, China's power battery volume reached 220GWh in 2021, with 175% growth compared to 2020. How to improve product quality, enhance battery safety and achieve zero customer complaints are the problems that every battery manufacturer needs to consider when facing fierce competition in the market.

LUSTER has been concentrating on the machine vision industry for over 20 years. In the lithium industry, LUSTER has always taken the responsibility to improve product quality, enhance battery safety and help customers achieve the goal of zero complaints through vision inspection technology and technological innovation according to customers' production process, in order to deal with the unpredictable market with constant quality pursuit. The related vision system products with fully independent intellectual property rights have been widely used in the upstream and downstream production lines of the lithium battery industry, including copper and aluminum foil inspection of raw materials, aluminum-plastic film inspection, diaphragm inspection, electrode coating and die-cutting inspection, stacked wrap inspection, back-end inspection, etc.

Diaphragm Inspection

As one of the key inner components of lithium batteries, the diaphragm separates the positive and negative electrode pieces to prevent short circuit and ensure the normal operation of the battery, and its performance directly impacts the capacity, multiplier, lifespan and safety of the battery, so effective quality control is essential.

The diaphragm material is a battery material with large capital expenditure and a relatively high technical threshold. From the industry, capital to ecology, the diaphragm market has undergone recent changes. According to GGII research data, in 2021, China's lithium diaphragm volume was 7.8 billion square meters, growing over 100% year on year with fierce competition. Diaphragm companies must improve quality and efficiency to reduce costs in order to protect profits, and it has made new demands to equipment manufacturers.

For the special needs of diaphragm inspection, LUSTER has proposed a lithium battery diaphragm inspection solution covering base film, coating, slitting, rewinding and other processes. Among them, the unique leaky coating and spray inspection technology can detect CCS leakage (PVDF leakage on the base film surface; PVDF leakage on the CCS of some products), and can also inspect single spray, single coating and single spray, single coating and double spray, double coating and double spray products of single/double side - the whole width of the leaky spray, partial leakage, partial lack of spray and other defects.

Electrode inspection

In the electrode inspection, LUSTER has solved the problem of unique materials, poor imaging and other difficulties in the electrode's inspection through the addition of several innovative technologies. LUSTER has achieved accurate imaging, different defects and simultaneous inspection.

Aluminum and copper are common electrode substrates, but due to the high reflectivity of the materials, regular imaging tends to "miss the mark". It is not possible to present images without overexposing the coating area, foil area, ceramic edge, etc. at the same time. The pattern of normal inspection in the coating area and overexposure in the foil area has become a " no choice" for many manufacturers. Manufacturers with prime requirements must ensure the inspection effect by increasing investment and setting up a duplex inspection. In response to such pain points in the lithium inspection process, LUSTER has introduced a lithium battery electrode inspection solution that enables simultaneous inspection of the coating area, ceramic area, and white-out area, ensuring the inspection of serious defects such as foil leakage and pinholes, as well as the inspection of low-contrast defects such as folds and dark marks. The defects are clearly displayed with obvious contrast, and it is compatible with both positive and negative electrode inspection. 

The defects of lithium battery electrodes are mostly in 3D form with height or depth information. However, the current conventional processing methods can only get 2D images of defects, which are very unfavorable for defect inspection and classification.

LUSTER has released an inspection solution for lithium battery electrodes that can take pictures of defects with 3D information using a 2D system. It can distinguish 3D defects from other defects, distinguishing different depths of similar defects, and distinguishing defect depths from background images. This makes the classification of defects simple and clear, and the manual double-checking is also clear at a glance.

LUSTER's lithium battery inspection solutions have been applied to battery manufacturers' customers, and these solutions cannot be completed without our "diamond", which is one of our technologies.

  • Self-developed underlying algorithm VisionWARE, speeding up and minimizing costs

Compared to conventional commercial algorithms and software development of underlying algorithms like open source OpenCV, LUSTER's customized underlying algorithms increase processing efficiency by over 50% and significantly reduce processing time. Taking a 16K x 1K monochrome image as an example, the processing time of VisionWARE is only 1/4 of that of OpenCV.

  • Conventional features + AI classification, a dual-pronged approach for accurate classification

Under the premise of accurate imaging, conventional methods mainly classify defects according to their size, area, contrast, etc., which is not very accurate.

Based on the characteristic that different process defects have different morphologies, AI classification can distinguish the appearance problems caused by different processes (foil leakage, folds, cracks, bubbles, electrode lug sticking material, gel agglomeration, dark/bright marks, etc.) based on morphology for quality tracing and help process improvement.

  • Intelligent interaction system, interconnection and intelligent communication

LUSTER's software system can run automatically without manual operation when linked with your company's own MES.

LUSTER's software system can also interact with the data center and the terminal storage to allow saving all of your enterprise's defect information and achieving data traceability.