Customized Microscopy Solutions for EV Battery Inspection

Lastly, Evident has developed custom operation procedures to simplify complicated analyses. One example is a software recipe/macro function for automated dimensional measurements.

This measurement is completed to check that the dimensions are within the specifications required by the manufacturer.

EV battery inspection challenges

Large-stage system with a modular microscope

Global electric vehicle (EV) sales have been growing steadily and are expected to reach more than 17 million vehicles in 2028. The rapid shift toward EVs means that new inspection solutions are needed to ensure the quality of critical components. For electric cars, these components include the battery cell package and copper and aluminum current collectors.

Custom confocal laser microscope system used for EV battery inspection
OLS5100 custom solution

Custom microscope systems include:

Published March 14, 2024, on Evident’s blog.


After an electrode is completed, the electrode is placed vertically. An inspector then uses a microscope to check the adhesion between the electrode material and the current collector from the cross section.

During lithium-ion battery manufacturing, several battery components are normally inspected: the current collector, electrode material, and separator.

4. Long and tedious analysis workflows slow the inspection process

Here are three examples of custom inspection solutions that Evident created for EV battery manufacturers, enabling them to inspect these critical components at their required volume.

Electric vehicle battery inspection

In both cases, seamless integration of motorized hardware (e.g., illuminator, nosepiece, stage) and intuitive software is crucial to meet the manufacturer’s requirements. When the hardware components are motorized and controlled by the customized software, operators’ workflows to perform specific tasks are made easier. This helps to minimize human errors and maximize work efficiency compared to a manual system.

Designing customized microscope solutions for EV battery inspection

Custom microscope system

These examples demonstrate some of the customized inspection solutions Evident can provide based on its core microscope technology. From enlarged stages to optimized workflows and added observation modes, a variety of options is available.

A third example integrates a large stage with the DSX1000 digital microscope. This solution is used to inspect burrs on the current collector and measure the thickness of the current collector and electrode material. Further, it can be used to analyze metal contamination and inspect scratches on the battery package.

Large-stage system with a laser confocal microscope

3. Electrode cross section

Depending on the shape of the defects, various measuring tools are required. Pairing your microscope with an easy-to-use imaging and measurement software can ease this process. One example is PRECiV image analysis software, which makes it easy to check the width, angle, and area measurement parameters of the defects. These include burrs protruding from the copper foil, scratches on copper and aluminum foils, and electrode thickness in the cross section of copper/aluminum foils and electrodes.

Large-stage system with a digital microscope

With these needs in mind, Evident developed customized microscope solutions that can measure a large sample in its entirety. Stage sizes ranging from 300 × 300 mm to 500 × 500 mm are typical examples that support large samples. These solutions can easily acquire images in various observation formats in 2D or 3D. Supported observation methods include brightfield, darkfield, DIC, POL, and MIX.

Surface inspection of a lithium-ion battery pack
Surface inspection of a battery pack using the DIC observation method

Industrial microscope systems can perform a variety of inspections on these lithium-ion battery materials.

Today, electric cars mostly use lithium-ion batteries. Although they are a popular choice due to their light weight and high energy density, capacity, and efficiency, lithium-ion batteries pose certain safety risks. For instance, a lithium-ion battery cell that short circuits can cause a fire, explosion, or other accidents. Contamination or damage introduced during the manufacturing process can also affect battery safety and performance. As a result, it’s critical to have rigorous inspection processes throughout battery production. To perform well, the entire EV power battery system depends on battery safety.

1. Roughness of the current collectors and electrodes

3D measurement of a burr on a lithium-ion battery sample
3D image of a burr: Advanced 3D measurement tools enable complex measurements, such as profile measurement and step height measurement between surfaces.

Roughness measurement of the current collector copper foil using the LEXT OLS5100 3D laser confocal microscope.

1. It’s difficult to acquire high-quality images of battery samples

Solution benefits include:
• A variety of fine defects or structures can be observed and measured.
• Analysis of the product surface topography is possible using measurement of line roughness and surface roughness.
• Images are acquired with a wide field of view and high resolution.

3. The inspection microscope can’t measure and observe large or varied samples

An important part of the quality control process is to inspect the surfaces and check for defects such as burrs, scratches, and metal contamination. Therefore, acquiring high-quality images of these aluminum and copper surfaces is an important step in quality control.

The electrode material and current collector must have high adhesion to maintain a stable battery capacity. The appropriate roughness level of the current collector depends on the type of electrode material applied. Therefore, controlling the current collector roughness is important for battery quality control.

Manufacturers often need to inspect larger and more varied samples to meet different client demands and specifications. Therefore, the microscope system must be versatile to handle both large and small sample sizes with flexible stage designs. 

Here’s a brief overview of each part:
• The current collector is a sheet-like metal that supplies electrical energy to the tab lead. In general, copper is used in the cathode and aluminum is used in the anode.
• The electrode material is pasted on the current collector to flow electrical energy. It’s a mixture of an active material, binder, and conductive material.
• The separator is located between the cathode and the anode to prevent an electrical short caused by their contact. It has many microsized holes, and only lithium ions can pass through them (unlike electrical energy).

Industrial microscope inspections of lithium-ion battery materials

Modular microscope system for EV battery inspection
BXFM custom solution

The MIX and differential interference contrast (DIC) observation methods are good options for detecting surface defects. They provide different lighting conditions that enhance certain features of the defects. For example, DIC observation can enhance height differences (in the nanometer range) on the defects, or sample surface waviness. With MIX observation, scratches can be enhanced with the darkfield and brightfield combination.

For good battery quality, the stacking processes in the battery manufacturing must have high quality control. A certain number of sheets of anode, separators, and cathode are stacked, and the stacked body is inserted into a battery container. After that, the tab lead, which transfers electricity to and from the outside, is welded at the inlet and outlet of the anode and cathode.

Performing these inspections can present multiple challenges, depending on your microscope systems and inspection requirements. Here are some common challenges and solutions.

A burr on a lithium-ion battery’s electrode material or current collector can result in an electrical short circuit, and the battery may overheat and even ignite during operation. Therefore, batteries must be strictly inspected for burrs to help ensure their safety.

Solution benefits include:
• It can be equipped with an optional tilting frame for side angle viewing up to 90 degrees in each direction, enabling users to visualize a sample from any angle.
• Various observation methods (e.g., brightfield, darkfield, MIX, DIC, POL, and oblique) help facilitate observation and analysis of battery samples, measurement of cross-section thickness and battery-pack dimensions, and identification of hard-to-find defects, such as burrs, metal contamination, and scratches.

2. A lack of measurement and support tools for battery sample analysis

Custom confocal laser microscope system used for EV battery inspection
DSX1000 custom solution

Learn more about custom microscopy solutions for EV battery inspection

4. Dimension of the battery packs

2. Burrs on the electrode or current collector

Inspection of an electrode plate burr
Observation of an electrode plate burr using the DSX1000 digital microscope
3D measurement of an electrode plate cross-section
3D measurement of an electrode plate cross section using the DSX1000 digital microscope

Depending on the customer requirements, Evident can design a customized solution to meet the exact specifications related to sample size, stage size, and what needs to be measured. Once the customer provides actual samples, Evident can determine if its existing microscope systems are suitable to acquire the images and measure the samples. If so, it can begin developing a solution that meets their required specifications.

Interest in automated measurement and inspection systems continues to increase. Generally, the requirements of an automated system using an optical microscope can be divided into two types:
• Detection and inspection of certain defects  
• Repeated and routine inspection workflow  

Tools that measure surface roughness measurement are also important. During the initial battery production process, surface roughness analysis is used to check the quality of the mixing and coating of the relevant materials. One good option is a laser confocal microscope, because it provides noncontact and high-precision measurement.

Evident developed a large-stage system for a customer based on the LEXT OLS5100 3D laser scanning confocal microscope. This solution analyzes pressed (stress) marks or particles on the copper current-collector surface. The width and height of the defects are easily measured. It also offers analysis of the surface roughness on aluminum and copper foils.

Solution benefits include:
• The battery cell, which is a large-sized sample, can be observed and measured by the customized stage in its entirety.
• X- and Y-plane measurements and Z-axis measurements can be used in various ways according to the sample structure of interest.

One example solution Evident designed for a customer is a large-stage system based on the BXFM modular focus system. The solution can measure battery pack dimensions and current collector defects in the EV battery manufacturing process.

If you have a unique or challenging requirement for your EV battery inspection, contact Evident. You can learn more about designing your own microscope with custom hardware and software by visiting the customized solutions page.