Cylindrical cells are widely recognized as the most suitable format for high-speed roll-to-roll production, offering scalability and manufacturing efficiency. However, despite their structural advantages, thermal management remains a critical design challenge, especially under high-power operating conditions.
Cylindrical cells are widely recognized as the most suitable format for high-speed roll-to-roll production, offering scalability and manufacturing efficiency. However, despite their structural advantages, thermal management remains a critical design challenge, especially under high-power operating conditions.
The Challenge of Heat Dissipation in Spiral-Wound Cells
Due to the spiral winding of the jelly roll, heat generated in the inner layers of the cell tends to accumulate, creating temperature gradients that can degrade performance and shorten cycle life. Efficiently transferring this heat from the cell core to its outer shell is essential for maintaining performance and safety, especially during high C-rate charge or discharge.
The Role of the Uncoated Copper Foil “Radiator”
To address this issue, manufacturers leave the final turn of the anode electrode uncoated—exposing a bare copper foil. This uncoated segment acts as a thermal conductor, channelling the heat from the inner windings directly to the cell casing, where it can dissipate more effectively. This simple yet effective design adjustment significantly enhances thermal performance.
In some advanced designs, the separator layer is also partially removed from the outer regions of the jelly roll to further improve heat transfer. By maximizing the direct contact between the copper foil and the cell casing, heat conduction is optimized without compromising safety or performance.
The C-Rate and Cooling Area Relationship
As shown in the below graph , there is a direct relation between the continuous discharge C-rate and the area of uncoated copper foil. Higher discharge rates generate more heat, necessitating a larger surface area to effectively remove it. This design principle is acting as cooling radiator for cylindrical cell formats.
Final Thoughts: Engineering Smarter Thermal Solutions
As the demand for higher-performance lithium-ion cells grows—particularly in electric mobility and aerospace sectors—thermal challenges will only become more critical. At AION Engineering, we specialize in custom cell architectures that optimize both electrochemical performance and thermal behavior, using deep material knowledge, commercial product data and simulation-backed design tools. Whether you’re scaling production or solving next-gen battery problems, AION delivers bespoke solutions with precision and purpose.
Stay tuned for more information and analysis on cell design!
Kerem Buğra Batuş, Cell Design & Process Development
At AION Engineering, we accelerate lithium-ion cell development using AI-driven design and advanced technologies, delivering innovative, sustainable energy solutions for a better future