Views: 0 Author: Site Editor Publish Time: 2026-01-16 Origin: Site
As the global energy transition accelerates and demand for renewable energy storage systems (ESS) continues to surge, battery technology is advancing rapidly to meet the challenge. Among the latest breakthroughs, the successful mass production of 684Ah stacked battery cells has captured industry attention and signaled a new era in large-format energy storage.
On December 23, 2023, battery manufacturer Sunwoda announced that its production line had delivered 1 million 684Ah stacked cells in just three months — a milestone that confirms the maturity of stacked battery cell technology and its readiness for large-scale deployment.
1 million 684Ah stacked cells produced in only 3 months, proving large-scale manufacturability.
Stacked cells outperform wound cells in safety, energy density, and cycle life—especially above 500Ah.
Advanced manufacturing & AI inspection reduce defect rates to PPB levels.
Over 70% of top battery makers are now investing in stacked cell technology.
684Ah stacked cells are becoming the preferred solution for utility-scale energy storage systems.
A 684Ah stacked battery cell is a high-capacity lithium-ion cell designed specifically for energy storage applications. Unlike traditional wound (or rolled) cells, where the electrodes and separator are wound into a spiral, stacked cells assemble these layers in a "book-like" fashion — layer by layer.
This structural difference eliminates internal stress points (common in wound cells), enables higher energy density, and improves overall thermal management. It's particularly effective for battery formats above 500Ah, where roll-based designs become difficult to manufacture safely.
One of the key challenges in stacked battery cell production has been minimizing defects such as particles, burrs, misalignments, and wrinkling during the stacking process. Sunwoda's achievement in producing 1 million cells in 3 months was made possible through a series of innovations:
Four-layer particle prevention system to eliminate contamination.
Hi-pot insulation testing and CIL ceramic edge-sealing to enhance electrical safety.
3-axis alignment platforms for precision stacking.
Triple-layer anti-wrinkle pressing technology.
On the quality control side, the production line includes:
230+ inspection items using 1,500+ sensors and AI vision systems.
2.5D image detection and full-line CT scanning for internal defects.
Achieving a PPB (parts per billion) defect level, ensuring reliability at scale.
While wound cells (cylindrical or prismatic) remain dominant in smaller applications like EVs and portable electronics, stacked cells offer unique advantages for high-capacity storage:
| Feature | Wound Cell | Stacked Cell |
|---|---|---|
| Energy Density | Moderate | Higher (no wasted R-corner space) |
| Internal Resistance | Higher | Lower (due to full-tab design) |
| Thermal Management | Less uniform | More uniform |
| Structural Stress | High at corners | Evenly distributed |
| Safety | More prone to lithium plating | Lower risk of short circuits |
| Scalability (>500Ah) | Limited | Ideal |
For cells above 500Ah, the wound process struggles with mechanical stress and uneven pressure distribution, while stacked designs maintain integrity, performance, and safety over long-term usage.
The 684Ah stacked cell is not just a technological leap for one company — it's a broad industry trend. Over 70% of leading battery manufacturers are actively developing or scaling up stacked cell production, including:
CALB
SVOLT
EVE Energy
REPT BATTERO
Sunwoda
This trend reflects the industry's shift from competing on cell size alone ("dimension race") to focusing on high-performance, scalable manufacturing processes.
By 2026, the production capacity of 600Ah+ stacked cells is expected to increase significantly, driven by growing demand from grid-scale ESS providers.
For utility-scale storage systems, the 684Ah stacked cell offers multiple system-level benefits:
Fewer cells per rack, simplifying system design and reducing BOM cost.
Lower internal resistance, improving round-trip efficiency.
Higher thermal stability, lowering the risk of thermal runaway.
Longer cycle life, reducing total cost of ownership (TCO).
System integrators are also adapting quickly, offering stacked-cell-compatible battery management systems (BMS) and thermal solutions, ensuring seamless integration into commercial and industrial energy storage deployments.
The mass production of 684Ah stacked battery cells marks a pivotal moment in the evolution of energy storage. It proves that high-capacity, high-performance batteries can now be manufactured at scale — cost-effectively and reliably.
As more manufacturers and energy providers embrace this advanced cell format, we can expect a new wave of efficient, safe, and scalable energy storage solutions to emerge — helping to accelerate the world's transition to clean energy.
Stacked cells assemble electrodes in layered formats, while wound cells roll them into a spiral. Stacked cells offer better energy density, lower internal stress, and improved thermal performance, especially in large-capacity formats.
684Ah represents a new benchmark in cell capacity for energy storage systems. It allows for fewer cells per rack, reducing complexity, improving efficiency, and lowering overall system cost.
Yes. Stacked cells have fewer stress points, lower expansion rates, and better thermal distribution, which significantly reduces the risk of lithium plating, internal short circuits, and thermal runaway.
Leading battery manufacturers like Sunwoda, EVE Energy, CALB, and SVOLT have already incorporated stacked cell lines into their production, with growing adoption expected globally.
Larger, safer, and more efficient battery cells enable scalable and cost-effective energy storage systems, which are critical for integrating renewable energy and balancing grid demand.
