Along with the widespread interest in renewable energy and initiatives aimed at realizing a decarbonized society, electrification of automobiles such as EVs and Energy Storage Systems (ESS) are now attracting attention. One key technology for these initiatives is rechargeable batteries, in particular, lithium-ion batteries. Electrode coating is an important manufacturing process that determines the quality of lithium-ion batteries. A poor finish could even lead to serious accidents such as ignition when using the batteries. The quality and yield depend greatly on whether the cathode and anode materials are coated evenly, so it is important to precisely measure and monitor the coating quality.
Here, we introduce Yokogawa’s solution at the coating process and WEBFREX3ES, an online thickness gauge for battery electrode sheets.
Over 50 Years of Film Measurement Performance, Over 10 Years of Experience in Delivery to Leading Manufacturers of Batteries
Lithium-ion batteries are now produced around the world, but they were put into practical use in Japan and rapidly expanded throughout the world subsequent to the 2000s.
Yokogawa has been developing technologies for controlling and measuring the quality of sheets online in the paper and film manufacturing process for over 50 years before WEBFREX3ES was launched in 2010.
Since then, Yokogawa has been supporting production sites and supplying WEBFREX3ES to more than half of the world's top 10 companies. Besides rechargeable batteries, WEBFREX3ES is also widely used at production sites for multilayer ceramic capacitors (MLCCs) and contributes to the improvement of quality and production costs.
The know-how of on-site operation monitoring and improvements accumulated over many years is the strength of Yokogawa's thickness gauge, and it is used effectively for today's WEBFREX3ES.
Accurate Monitoring of Coat Weights, Quality/Cost Improvements and Collective Manufacturing Management Using Coat Weight Data
WEBFREX3ES permits accurate, high-speed and high-resolution measurements with high-performance frame and sensor. In addition, it provides you a rich monitoring environment with user-friendly, high visibility and flexibility interfaces.
It contributes to not only monitoring the coat weights, but also improving the quality and costs online using Yokogawa’s automatic coating control software (as option*).
*Consultation is required if you wish to add this option.
In addition, it can correspond to external communications, and support collective manufacturing management and communications with external facilities in coordination with MES.
WEBFREX3ES can be measured at up to five different positions (#1 to #5). The thickness of the foil before coating, respective coating weights for its front and back sides just after coating (#2 & #4) and after drying (#3 & #5) will be led by calculating difference using the measured values of each frame.
WEBFREX3ES consists of two parts: a frame main body and a local box.
The frame body is equipped with the dedicated sensor and can measure the thickness by scanning sheets from one end to the other. Whereas, the local box houses the frame processor, motor driver and multi-frame synchronous processor, and can be installed at a location some distance from the frame body.
High-speed and High-resolution Measurements by Using Linear Motors
WEBFREX3ES is equipped with linear motors, which have enabled us to measure high-resolution by realizing high-speed scan with the shortest time of 3 seconds for one-way.
These makes it possible to perform sufficient measurements even on production lines with high-speed production capability and to precisely monitor the edge parts of the electrodes considered important when laminating them.
Accurate Coat Weight Measurement With Synchronous Measurement System
Accurate Coat Weight Measurement With Synchronous Measurement System Coat weight data can be determined by calculating the difference between the basis weights of an uncoated object and a coated one. Since the basis weights which were measured in respective frames include uneven thickness of the foil and fluctuations of the coat weights, the "synchronous measurement" which matches the measurement points before and after coating would be an extremely important process to calculate accurate coat weights.
Accurate coat weights can be measured without being affected by the foil fluctuations by using linear motors with high accuracy positioning resolution in addition to improving the communication speed between frames installed before and after coating.
Measures to Prevent Dust Contamination
Dust contamination in the electrode sheets can cause a short circuit which may further lead to ignition while using the batteries. To prevent these from happening, a cover to prevent dust from scattering has been installed on the linear motor part above the sheets. In addition, linear motors have been designed to generate less dust by friction compared to conventional belt motors.
This is a transmission sensor using Beta-ray or X-ray.
Both of them are non-contact sensors and continuously measures the object with high accuracy without damaging it.
When the radiation emitted from the radiation source or X-ray tube transmits through the electrode sheets to be measured, the weight (basis weight) per unit area is measured by applying the principle of the attenuation according to the weight of the sheet.
Measuring the basis weight can detect the variations of not only thickness but also density unlike the laser type which measures thickness (um) only.
Beta-ray sensor (Radiation source: 85Kr)
Measurement range: 0 to 1200 g/m2
X-ray sensor (Reflection type X-ray tube and tungsten target)
Measurement range: 0 to 600 g/m2
Operation Screen That Does not Overlook any Minor Changes
A variety of operation screens suitable for the purposes are prepared such as profiles appropriate for real-time monitoring, 2D/3D Profile appropriate for monitoring and analysis of the entire trends, enlarged profiles appropriate for monitoring the edges, and zone trend profiles appropriate for monitoring the stripe coat trends.
From these operation screens, it is possible for users to configure the screens according to their preferences.
We will support them to timely display and communicate the necessary information, and to make a quick judgment.
In addition, its alarm function can help prevent the oversight of quality non-conformance by outputting the alarm for the external part of WEBFREX3ES in coordination with user systems such as a reminder system with buzzer and MES when the target value is exceeded.
Top: Profile, Middle: Overlay Profile, Bottom: Frame Control (for operation commands)
→ Optimum approach to the general monitoring, etc.
→ Optimum approach to monitoring and analysis of the general trends
Top: Respective zone trends for the left and right coated parts
Bottom: Profile and respective zone trends for the left and right coated parts
→ Appropriate for monitoring the stripe coated part trends
Simple Measurement Tuning
Although tuning is normally performed by applying some complicated calculations, as for WEBFREX3ES, auto-tuning is performed by simply inputting the measured values of each frame. It is not required for you to inquire engineers in charge of thickness gauge every time.
In addition, the set values can be saved according to each recipe (grade) and they can also be called smoothly even if the grade is switched in the process of manufacture.
Automatic Coating Control
It is expected that the automatic coating control software (option) will reduce the operation man-hours, pursue quality improvements as high as the level unachievable manually, and prevent production losses by the processes of both yield improvement and production line setup time reduction.
Coordination With MES and External Equipment
WEBFREX3ES can communicate with external systems and equipment and it can create an open network. It is possible not only to output the measurement data, operation status of thickness gauge and abnormal quality alarm externally, but also to send the command operations such as scanning from outside.
It can contribute to centralized production management in coordination with other line equipment by communicating with MES, etc.
It is also possible to communicate with equipment such as coating machines.
Click here for the solutions for batteries other than WEBFREX3ES.
Quality Improvement and Troubleshooting Using Past Data
Measurement data can be automatically saved in real time.
Therefore, profile management corresponding to the product lot numbers is possible and reliable traceability can be provided when analyzing the cause in case of trouble.
"Profile Stack Server" and "3D Profile Window" are available for quality and production management functions as optional software.
Profile Stack Server Function
Profile data of the electrode sheets which was coated with the electrode material can be automatically saved in real time.
Since each profile is saved based on the sheet length, managing profiles corresponding to the product lot numbers is possible.
It is also possible to save long-term profile data and check them back easily.
The open connectivity and database structure make it easy to refer to data of user systems and to perform efficient quality management.
In addition, it is easy to expand the data storage capacity since using general-purpose computers.
3D Profile Display Function
The profile data which Profile Stack Server has collected can be shown and analyzed as a three-dimensional graph.
Profiles as well as trends in machine direction can be shown according to the coating patterns such as intermittent coating and stripe coating. In addition, points where you want to analyze can be enlarged and shown, which are useful for quality improvement activities and past trouble analysis.
The Compact O frame and Beta-ray sensor can be conformed to the following standards according to the destination.
Please contact our sales representatives for the details when installing the X-ray sensor.
China National Standards
[CE Marking] EMC Directive
[CE Marking] Machinery Directive
EN IEC 63000
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