In the era of electrification, the battery is often regarded as the “heart” of an electric vehicle (EV). Its performance, safety, and lifespan directly define the vehicle’s driving range, reliability, and overall competitiveness in the market. It requires every detail in perfection in battery cell assembly–from coating and slitting to stacking or winding, each step and battery assembly equipment must be executed with exacting precision to ensure consistent electrochemical performance and structural integrity.
Among the many processes involved, battery winding stands out as a critical step that determines the internal structure and consistency of each cell — directly influencing how efficiently and safely an EV stores and delivers energy. A well-executed winding process not only improves cell uniformity and longevity but also enhances overall production efficiency and cost-effectiveness.
Understanding the Battery Cell Winding Process
The result of the battery cell winding is that the electrodes and separators are precisely rolled together to form the internal “jelly roll” structure. This compact, layered configuration determines how ions flow during charge and discharge in prismatic or cylindrical cells. It is essential to achieve consistent energy density, safety, and cycle life.
The process begins with pre-cut electrode sheets — the positive and negative electrodes — and separator films that prevent short circuits while allowing ion exchange. These materials are carefully aligned and fed into a winding machine, which rolls them into a tightly controlled spiral or oval shape and is fixed by an adhesive strip at last.
Depending on the cell type, the winding process may include jelly roll insertion into a metal casing (for cylindrical cells) or flattened winding (for prismatic cells) to optimize space utilization.
After winding, the electrode roll is secured, tagged, and transferred for electrode tab welding and electrolyte filling, marking the transition from mechanical assembly to electrochemical activation. In essence, precision in winding establishes the foundation for a battery’s overall performance — any deviation introduced at this stage can propagate through the rest of the manufacturing process, affecting output quality, yield, and reliability.
Battery Cell Winding in EV Battery Assembly: What Can It Achieve?
1. Production Efficiency
In stacking-based cell assembly, each battery requires dozens of individual electrode pieces, and each piece involves four cutting surfaces. This repeated cutting increases material handling, as well as raises the risk of burrs, edge defects, and misalignment, which can lead to higher defect rates and lower yield.
In contrast, cell winding technology uses continuous electrode rolls and separator films, eliminating the need for repeated cutting and stacking operations. It directly reflects that winding can shorten the time to proceed to the next step, cell packaging, compared with stacking. So, it finally achieves better production efficiency, supports large-scale automation, and reduces both material waste and manufacturing costs. It is an effective solution for meeting the demands of high-volume EV battery assembly.
2. Compact Design
Battery cell winding enables electrodes and separators to be tightly rolled with minimal gaps, forming a dense and uniform structure. This compact configuration allows more active material to fit within a given volume, improving the energy density of cylindrical and prismatic cells. For EV manufacturers, this technique can deliver a longer driving range without enlarging battery pack size.
However, in prismatic cells, the winding pattern creates curved edges that would not fully occupy the rectangular space within the cell casing. This leads to a small degree of space utilization loss compared with the stacking process, which arranges flat electrode sheets neatly to fill the entire rectangular volume.
Even so, winding remains one of the preferred methods in many prismatic EV battery designs because its compact and structural uniformity often outweighs the minor trade-off in space utilization.
3. Customizability
Battery cell winding also gives manufacturers broad flexibility in cell design and engineering customization. By adjusting parameters such as electrode length, winding diameter, and layer count, the same process can produce cells with different capacities, voltage ranges, or dimensions. This adaptability allows manufacturers to optimize cells for various EV platforms — from compact power cells for hybrid systems to large-capacity modules used in long-range electric vehicles.
Meet Better Scalability in Cell Winding: LEAD’s EV Laser Notching and Winding Machine
Battery cell winding offers clear advantages over stacking — from higher production efficiency and structural uniformity to improved mechanical stability and design flexibility. Yet, realizing these benefits in large-scale production depends on the technology and accuracy of the winding equipment itself.
LEAD’s EV Laser Cutting and Winding Machine is designed to meet these challenges with exceptional accuracy and production reliability. It integrates intelligent monitoring and control technologies to deliver consistent and reliable winding results.
Closed-loop Tension Control System: Continuously measures and adjusts electrode tension in real time, maintaining fluctuation within ≤±3%, ensuring uniform winding tightness and material stability.
Variable Angular Speed (Constant Linear Speed) Winding: Accommodates different mandrel sizes while keeping the electrode feed rate constant, minimizing stress and edge distortion.
Tab Holding Plate & Tab Folding Inspection: Guarantees precise tab alignment and folding during electrode passage, improving welding quality and overall cell consistency.
For more details about LEAD’s intelligent equipment or to explore how the EV Laser Cutting and Winding Machine can enhance your production line, please visit LEAD’s official website, https://www.leadintelligent.com/en/. Or, you can also contact their technical team directly for consultation according to your specific EV battery manufacturing demands!
