Lithium-ion Battery Stacking Technologies

Lithium-ion battery stacking technology is a critical process in cell manufacturing, directly impacting performance, safety, and production efficiency. At TOB NEW ENERGY, we specialize in providing turnkey battery production line solutions and cutting-edge equipment tailored to optimize these advanced processes. Currently, four primary stacking technology routes dominate the industry: Z-Folding, Cut & Stack Integration, Thermal Lamination Stacking, and Stack & Folding (LG's proprietary method). While Z-Folding and Cut & Stack Integration (essentially an enhanced Z-type) are widely adopted in China, Thermal Lamination offers superior speed and quality with higher complexity. Internationally, LG Energy Solution utilizes the highly efficient, patent-protected Stack & Folding method.

Table: Comparison of Main Stacking Technologies (Stack & Folding is LG Patent)

Detailed Analysis of Lithium-ion Battery Stacking Technologies

Z-Folding Technology

• The most common method involves a movable table pulling the separator back-and-forth (Z-shape) between platforms, alternately stacking anode and cathode sheets. While established, it faces inherent challenges:
• Separator Deformation: The oscillating motion creates asymmetric tension, leading to inconsistent stretching, deformation, and changes in porosity, pore size, and surface area – ultimately compromising cell quality. Explore our customized battery equipment solutions designed to mitigate such process challenges.
• Limited Efficiency: The need to swing the separator for each electrode placement restricts speed. Typical rates are 0.5s/piece/station. For a 30-layer cell, this means 15 seconds per cell, or just 4 cells per minute (4 PPM). This bottleneck hinders high-volume production.

Cut & Stack Integration Technology

• An evolution of Z-folding, this integrates die-cutting/laser cutting, Z-folding, and tab welding/pressing into a single machine, becoming a key industry trend due to improved yield and speed.
• Enhanced Yield: Combining processes minimizes electrode handling and transfer between stations, significantly reducing risks like damage, burrs, tab bending, and misfeeds during pick-and-place from cassettes. Discover our integrated battery pilot line solutions that leverage this efficient technology.
• Increased Speed: Electrodes and separator are fed and folded simultaneously. After reaching the set count, the separator is cut, tabs welded, and the stack pressed. Leaders like Hangke (Hefei) achieve up to 800 PPM (0.075s/piece), while Hymson reports 0.15s/piece (3-station).

Thermal Lamination Stacking Technology

• This advanced process feeds cathode roll, anode roll, and adhesive-coated separator simultaneously. Electrodes are cut in-line. The combined strip enters a heating system, undergoes thermal lamination and calendering, is cut into individual units ("Bi-cells"), and stacked mechanically. The stack is finally hot-pressed.
• Key Advantages: Continuous, unidirectional feeding ensures stable tension and speed, eliminating separator deformation issues seen in Z-folding. This results in superior stack flatness, consistent separator properties (mechanical strength, porosity), and optimal electrode-separator interfaces, leading to higher quality cells, especially for large-format, high-energy-density applications. While technically complex (involving lamination, precise cutting, and posing challenges for later electrolyte filling), its integrated approach (combining forming, stacking, pressing) is space-efficient and highly productive. For cutting-edge applications like solid-state batteries or dry electrode technology, robust stacking solutions are crucial.

Stack & Folding Technology (LG Patent)

• Developed by LG Energy Solution (equipment by MANZ), this proprietary method involves cutting electrodes, placing them onto a separator via rotating tables/vacuum chucks, then folding/rolling the assembly to interleave the electrodes. LG utilizes its proprietary SRS (Safety Reinforced Separator) – a ceramic-coated, heat-treated separator enhancing mechanical strength and safety by preventing internal shorts. While highly efficient, this technology is protected by LG patents and not commercially available to other manufacturers. Need advanced battery materials like specialized separators? TOB NEW ENERGY provides comprehensive battery material support.

Future Trends in Lithium-ion Battery Stacking Technology

Stacking technology continues to evolve rapidly:

• Rise of Cut & Stack Integration: As the dominant domestic Z-folding method faces yield and speed limitations, Cut & Stack Integration is becoming the preferred choice in China. Its integrated design significantly boosts yield and efficiency.
• Relentless Focus on Speed: Overcoming the historical efficiency gap compared to winding is paramount. Major Chinese equipment manufacturers are intensely focused on increasing stacking speeds (PPM) to make stacking competitive for mass production across more applications. Achieving this is key to wider adoption versus winding.

Optimize Your Stacking Process with TOB NEW ENERGY

Understanding the nuances of stacking technologies is vital for selecting the right process for your battery's performance, safety, and production goals. TOB NEW ENERGY offers unparalleled expertise and solutions:

• Tailored Stacking Equipment: We provide customized Battery stacking machines (Z-type, Cut & Stack, Thermal Lamination) designed for your specific R&D, pilot, or mass production needs.
• End-to-End Production Lines: From lab-scale to GWh-scale factories, we deliver complete, turnkey battery production lines incorporating the optimal stacking technology for your application.
• Advanced Material Supply: Source high-performance separator films, electrode materials, and adhesives critical for advanced stacking processes through our comprehensive battery materials portfolio.
• Cutting-Edge Technical Support: Leverage our deep expertise in next-generation battery technologies (solid-state, sodium-ion, Li-S) to optimize your stacking process and overall cell design.

Contact TOB NEW ENERGY today to discuss how our integrated battery solutions can enhance your stacking process efficiency, yield, and final cell quality.