Using simulation to improve battery coating uniformity by 11 percent and reduce defect rates by over 50 percent

Using simulation to optimize coating processes

When manufacturing battery electrodes, the coating’s quality is pivotal for determining the longevity, performance and safety of the cells. Specifically, inadequate coating on the anode relative to standard levels can result in a decline in lithium-ion absorption capacity, potentially leading to issues such as lithium plating, reduced capacity and shortened cell lifespan. This results in electrochemical performance imbalance between the cathode and anode, which negatively impacts overall cell performance. To address these challenges, an approach was necessary to predict coating performance and stability through presimulation and derive an optimal design.

SK On, a subsidiary of SK Innovation, applied a new approach using Siemens Digital Industries Software’s Simcenter™ STAR-CCM+™ software to predict and optimize the design variables and operating conditions of the coating process in advance. Simcenter is part of the Siemens Xcelerator business platform of software, hardware and services.

Leveraging simulation to predict flow prior to application

A slot die coater applies liquid or molten materials evenly and precisely onto a substrate. With precise flow rate and velocity control, it forms ultra-thin coating layers, making it widely used across various industries such as batteries, electronics, energy and displays. To simulate the entire slot die coating process, SK On used Simcenter STAR-CCM+, calculating flow distribution accurately from the moment the coating material flows through the manifold inlet to the point of application on the substrate.

According to the simulation results, SK On consistently maintained the variations in flow rate and pressure distribution across the entire coating width below 3 percent. Thus, the company achieved a high level of coating uniformity without needing additional test design procedures, facilitating the realization of high-quality coatings.

Additionally, SK On developed a quantitative model to predict coating quality across the entire coating width based solely on inlet flow conditions. Based on this, the company implemented a system to reliably set process conditions without prototypes.

Enhancing productivity and reducing defects

In the electric vehicle (EV) battery industry, addressing fast charging and ensuring stability are paramount. Based on Simcenter STAR-CCM+ simulation results from modifying the shape of the slot die coater, SK On constructed a model that more closely matched the target process conditions. SK On applied this design subsequently to their mass production processes, which proved capable of stable, long-term operation.

Additionally, by obtaining a more advanced analysis program than those of existing slot die manufacturers, the company moved away from relying solely on measurement instruments or sensory perception to evaluate issues on site. Instead, they can now incorporate theory-based analysis results into the design and predict potential issues in advance. This allows the company to effectively reduce costs associated with repetitive experiments and design changes.

Improving processes and data sharing methods

The existing coating process was inefficient, requiring a significant amount of time for trial runs when conditions changed and reprocessing was unavoidable if problems arose. To address these challenges, SK On explored options for developing analytical tools for slot die design and determined that leveraging SK Innovation’s high-performance simulation analysis program would be an effective solution.

By combining SK On’s process expertise with SK Innovation’s simulation analysis capabilities, the two companies adopted Simcenter STAR-CCM+ and established a foundation to predict and optimize process conditions in advance.

This approach enabled the companies to identify and manage potential issues early during the precheck phase, thereby minimizing trial and error.

Additionally, by obtaining simulation-based quantitative data, they enhanced the objectivity and speed of decision-making and made communicating between the design and production departments and suppliers more efficient, reducing rework time.

Expediting analysis using the replace part feature

Using the Simcenter STAR-CCM+ replace part feature allows users to quickly replace parts within computer-aided design (CAD) models. With this feature, engineers can streamline design change tasks and seamlessly update simulation models.

SK Innovation leveraged the Simcenter STAR-CCM+ replace part feature, which supports the entire process from preprocessing to postprocessing on a single platform. Thus, the company could quickly replace geometries and automate repetitive analysis tasks without rebuilding the entire model. With these functional advantages, they significantly reduced work time and provided a foundation for more flexible responses to design reviews and condition changes.

Achieving process-wide transformation

For SK Innovation and SK On, these achievements go beyond simply introducing simulation tools to drive practical innovation across the entire process, from product development to manufacturing and supply chain management.

In terms of product development, they used simulation to optimize the coater structure and accurately predict performance without experimentation.

"Using Simcenter STAR-CCM+ has shown to be significantly more precise and reliable than traditional methods,” Kim Sujeong, professional manager on the computational science team at SK Innovation. “Leveraging Siemens solutions plays a crucial role in improving coating uniformity by over 11 percent compared to previous methods.”

Additionally, they were able to file two patent applications to validate the technological capabilities.

During the manufacturing stage, the companies reduced the time required for process stabilization and minimized trial and error for quickly responding to changes in coating conditions, which reduced commissioning lead time by over three months.

Lastly, for supply chain management, the company’s quality improvement efforts yielded notable results, including reducing defect rates for specific products by over 50 percent, and increasing productivity by over 1.4 percent. Further, the company enhanced collaboration stability and reliability by promptly addressing partner requests.

With these changes, SK On achieved clear time savings and cost efficiency compared to the previous repetitive commissioning and rework-centric approach.

The company now has the capacity to conduct high-precision simulation analysis, a task that was previously challenging for its partner companies, with full commitment to designing and manufacturing equipment based on its proprietary designs and implementing them in real-world production settings.

“With Simcenter and by predicting and securing data results that were previously thought to be achievable only on site, we have made significant contributions to the overall growth of battery technology,” says Kim Juhyun, professional manger and group leader of the electrode process technology team at SK On.

Creating higher quality batteries while strengthening competitiveness

Introducing Simcenter STAR-CCM+ into SK On’s processes has yielded significant benefits by accurately predicting flow characteristics and coating material uniformity. With Simcenter STAR-CCM+, the company eliminated inefficiencies in existing processes and improved design reliability and quality stability.

“By being able to predict the results of conditions in advance using Simcenter STAR-CCM+, we can now utilize time and resources more efficiently,” says Park Jiyeon, professional manager on the electrode process team at SK On.

This simulation-based design optimization also led to reduced manufacturing costs, decreased defect rates and increased productivity, ultimately contributing to improved customer satisfaction and enhanced market competitiveness.

Thanks to this collaboration, SK Innovation also advanced its simulation analysis capabilities while SK On achieved tangible improvements in battery quality. By working together, both companies achieved their shared goal of strengthening their technological competitiveness.

After these successes, SK Innovation aims to establish Simcenter STAR-CCM+ as a core tool for driving product quality improvement and process optimization across various SK affiliates, forming the basis for ongoing joint development and integrated operational strategies.