What is Battery Stacking Process？

English Translation Battery manufacturing processes mainly fall into two technical routes: stacking and winding. Currently, Chinese battery enterprises predominantly focus on winding technology. Nevertheless, with advances in stacking technology, numerous battery manufacturers have ventured into the stacking sector. Recent battery market research indicates that major battery companies have formulated development plans for stacked batteries. Driven by the trend of large-sized prismatic batteries and upgraded stacking equipment, the stacking process is poised for large-scale industrial application. This raises key questions: what is battery stacking technology, what are its merits, and why leading battery manufacturers are actively investing in stacked battery production?

1. Definition of Battery Stacking Process

Stacking refers to alternately laminating electrode sheets and separators to form multi-layered cell cores. Compared with winding, stacking boasts superior performance in energy density, safety and cycle life.

Among three mainstream lithium battery formats, cylindrical batteries exclusively adopt winding, pouch batteries solely use stacking, while prismatic batteries support both processes. Global leading battery firms are gradually shifting their product roadmap toward stacked batteries.

Stacking effectively eliminates core defects such as powder shedding and gaps caused by bending electrodes and separators in winding production. It also delivers better rate capability than conventional winding, center-tab winding and multi-tab winding structures. Domestically, BYD and CALB demonstrate mature stacking application with rapidly rising production efficiency, which even surpasses winding in certain scenarios.

Still, stacking has drawbacks including relatively low initial productivity and high equipment investment costs.

2. Advantages of Battery Stacking Process

Stacked cells achieve remarkably better comprehensive performance than wound cells with inherent limitations.

Wound electrodes feature curved edges after rolling. Deformation and distortion easily occur during charging and discharging, impairing cell performance and triggering safety hazards. Uneven current distribution also leads to severe voltage

polarization and unstable discharge voltage. In contrast, stacking keeps electrodes and separators flat without bending during assembly. This design cuts internal resistance and boosts power output. Flat contact interfaces enable synchronous expansion and contraction of electrodes, uniform deformation and electric field distribution, facilitating electron movement and faster charging and discharging.

Under the same volume, stacked cells deliver approximately 5% higher energy density and longer cycle lifespan.

Stacked cells also gain enhanced safety. Farasis Energy’s stacked pouch cells show no open flame or even smoke in nail penetration tests, thanks to optimized heat dissipation. Wound cells dissipate heat only along the winding axis with poor thermal conductivity due to dense layers. Stacked cells have fewer laminated layers and larger surface area, realizing efficient heat transfer and superior thermal stability.

In summary, stacking outperforms winding in energy density, safety and charge-discharge efficiency.

3. Reasons for Leading Manufacturers’ Heavy Investment in Stacking

World-renowned battery enterprises including LG Energy Solution, BYD, SK On, CALB, Envision AESC and Farasis Energy have all launched stacking-based product layouts.

Domestically, on November 2, CALB announced mass production of its self-developed 3rd-generation high-speed stacking technology. Integrating electrode thermal bonding and multi-piece stacking, the process reaches a speed of 0.125 seconds per piece, marking a over 200% efficiency surge versus the 2nd generation. It also reduces equipment floor space by over 40%, with improved product safety and yield rate. As a pioneer applying high-speed stacking to prismatic batteries, CALB’s breakthrough accelerates the industry transition to stacking era.

On September 9, Farasis unveiled the Super Pouch Solution (SPS). The cell adopts full-tab stacking structure, equipped with liquid cooling plates, nano thermal insulation materials and low-temperature rapid self-heating design for outstanding cold resistance.

On September 3, Sunwoda released the SFC480 ultra-fast charging power battery. Featuring stacking and tabless connection technology, it applies 100% CT inspection to secure stacking precision within ±0.1mm, paired with online CCD detection to control defective products.

BYD launched Blade Battery in March 2020. Manufactured via stacking, it maintains alignment tolerance within 0.3mm with a stacking speed of 0.3 seconds per cell.

CALB rolled out the world’s original full-tab stacking technology in 2019, fundamentally solving lithium precipitation risks at winding corners and elevating safety. In Q2 2022, its upgraded integrated full-tab thermal bonding cutting-stacking system achieved massive leaps in efficiency and precision on prismatic battery production lines, hitting 500 pieces per minute with stacking accuracy up to 0.25mm.

All Envision AESC pouch batteries adopt stacking technology. Internationally, most LG Energy Solution pouch cells apply stack-and-fold structure, while SK On’s proprietary stacking technology prevents core distortion during cycles for extended lifespan and higher safety.

Market forecasts project the global stacking-process battery capacity will hit 845GWh by 2027, explaining manufacturers’ aggressive layout strategies.

Grepow is an early domestic developer of stacked pouch lithium batteries. Its lithium battery division was founded in 2007, focusing on R&D and production of stacked lithium polymer cells. Up to now, it has grown into a prestigious stacked lithium polymer battery supplier worldwide. Its products are widely applied in drones, RC models, agricultural plant protection vehicles, sports cars, auto parts, medical devices, outdoor equipment, marine facilities, military equipment, industrial machinery, wearable devices, AR/VR devices and consumer electronics.