# Building and forming a battery cell

> Cell assembly on one page: winding and stacking in a dry room, cylindrical, prismatic and pouch formats, an 18650 cell in section with its mandrel, PTC switch and CID vent disk, the tabless 4680 design, and electrolyte filling, formation and aging. Every step and number is quoted from the cited papers.

- Page: https://www.labcanvas.com/templates/energy-storage-guides/building-forming-battery-cell
- Open in the LabCanvas editor (LabCanvas account): https://www.labcanvas.com/editor.html?template=battery-cell-assembly-formation
- Updated: 2026-10-14
- Category: Battery & energy storage guides
- Method: Cell assembly and formation
- Starting materials: Coated, calendered and slit electrodes, PP or PE separators, tabs, cans or pouch foil and electrolyte
- Product: Formed and aged cylindrical, prismatic and pouch cells
- Key result: Cells and machines drawn by LabCanvas after the cited descriptions and CT studies; layer counts and thicknesses are drawn, not to scale, and the 18650 header and the 4680 are not to scale either
- Figure: 1920 × 1080 px, 45 editable layers (6 generated objects with settings)

## Steps

1. **Winding**: In a dry room the electrodes and dried separators are wound for cylindrical and prismatic cells, and Al and Cu tabs are welded to the cathode and anode current collectors, most often ultrasonically (Liu 2021). PP or PE separators, such as a PP/PE/PP trilayer, are a separate processing step, as they cannot be slot-die coated like the electrodes (Katz 2024)
2. **Stacking**: Pouch cells are stacked layer by layer; welding is 7.34% of the manufacturing cost and under 2% of its energy (Liu 2021). Pouch electrodes are layered in a sandwich sealed in flexible foil, usually an aluminium core with non-conductive polymer outer layers; in one commercial cell the cathode was 120 μm thick, the anode 130 μm and the separator ≈20 μm (Stravova 2024). CT scans of commercial cells show defects such as anode–cathode overhang violations (Condon 2024)
3. **Three formats**: Cylindrical, pouch and prismatic cells are used in electric vehicles; pouch and prismatic cells are flat (Stravova 2024), and cylindrical cells come as 18650, 2170 and 4680 (Condon 2024). Prismatic cells are built like cylindrical ones with an elliptical winding, in a hard case of aluminium or stainless steel, and use space efficiently (Stravova 2024); the three designs are made in very similar ways (Liu 2021)
4. **18650 in section**: An 18650 cell is 18 mm across and 65 mm long; its rigid casing makes it a pressure vessel when gas forms. A mandrel supports the electrode assembly and keeps a path open for gas; the CID vent disk, domed toward the electrodes, turns convex as the pressure rises and disconnects the circuit, then its scored annulus ruptures to vent; the PTC switch is a conductive polymer whose resistance rises greatly when hot (Finegan 2018)
5. **Tabless 4680**: In the tabless 4680 design the uncoated edge of the electrode serves as the tab, joined to a multi-contact case bottom: this lowers the cell’s impedance and heat, and dropping the tabs together with the larger cell raises the energy density by 16% (Liu 2021)
6. **Filling, formation, aging**: The enclosure is filled with electrolyte before the final seal; the cell is charged to a low voltage (e.g. 1.5 V) to protect the copper current collector, rested for wetting and cycled at a low rate such as C/20, then faster, so a stable SEI forms on the anode. The gas is let out, the cells age on shelves and are degassed again before the final seal. Formation and aging take up to 3 weeks and 32.16% of the manufacturing cost; one protocol cycling between 3.9 and 4.2 V took about 14 h, 8.5 times faster (Liu 2021)

## Strengths

- Dropping the tabs and enlarging the cell raises the energy density by 16% (Liu 2021)
- Prismatic cells use space efficiently (Stravova 2024)
- A stable SEI protects the anode during fast charging (Liu 2021)

## Limitations

- Formation and aging take up to 3 weeks (Liu 2021)
- An 18650’s rigid casing makes it a pressure vessel when gas forms (Finegan 2018)
- A prismatic cell’s inner construction strongly influences its risk of inflation (Stravova 2024)

## References

1. Liu, Zhang, Wang & Wang, “Current and future lithium-ion battery manufacturing”, iScience 2021. https://doi.org/10.1016/j.isci.2021.102332 (primary)
2. Katz & Cobb, “High-viscosity phase inversion separators for freestanding and direct-on-electrode manufacturing in lithium-ion batteries”, ACS Appl. Mater. Interfaces 2024. https://doi.org/10.1021/acsami.4c09342 (primary)
3. Stravova et al., “Comprehensive study of rapid capacity fade in prismatic Li-ion cells with flexible packaging”, Sci. Rep. 2024. https://doi.org/10.1038/s41598-024-77673-3 (primary)
4. Condon et al., “A dataset of over one thousand computed tomography scans of battery cells”, Data Brief 2024. https://doi.org/10.1016/j.dib.2024.110614 (primary)
5. Finegan et al., “Identifying the cause of rupture of Li-ion batteries during thermal runaway”, Adv. Sci. 2018. https://doi.org/10.1002/advs.201700369 (primary)

Credit: Drawn by LabCanvas after Liu, Zhang, Wang & Wang, iScience 2021 (doi:10.1016/j.isci.2021.102332), Finegan et al., Adv. Sci. 2018, Stravova et al., Sci. Rep. 2024 and Condon et al., Data Brief 2024, and the papers in the details.

## Questions

**What does the “Building and forming a battery cell” template show?** Cell assembly on one page: winding and stacking in a dry room, cylindrical, prismatic and pouch formats, an 18650 cell in section with its mandrel, PTC switch and CID vent disk, the tabless 4680 design, and electrolyte filling, formation and aging. Every step and number is quoted from the cited papers.

**What are the steps shown in “Building and forming a battery cell”?** 1. Winding: In a dry room the electrodes and dried separators are wound for cylindrical and prismatic cells, and Al and Cu tabs are welded to the cathode and anode current collectors, most often ultrasonically (Liu 2021). PP or PE separators, such as a PP/PE/PP trilayer, are a separate processing step, as they cannot be slot-die coated like the electrodes (Katz 2024). 2. Stacking: Pouch cells are stacked layer by layer; welding is 7.34% of the manufacturing cost and under 2% of its energy (Liu 2021). Pouch electrodes are layered in a sandwich sealed in flexible foil, usually an aluminium core with non-conductive polymer outer layers; in one commercial cell the cathode was 120 μm thick, the anode 130 μm and the separator ≈20 μm (Stravova 2024). CT scans of commercial cells show defects such as anode–cathode overhang violations (Condon 2024). 3. Three formats: Cylindrical, pouch and prismatic cells are used in electric vehicles; pouch and prismatic cells are flat (Stravova 2024), and cylindrical cells come as 18650, 2170 and 4680 (Condon 2024). Prismatic cells are built like cylindrical ones with an elliptical winding, in a hard case of aluminium or stainless steel, and use space efficiently (Stravova 2024); the three designs are made in very similar ways (Liu 2021). 4. 18650 in section: An 18650 cell is 18 mm across and 65 mm long; its rigid casing makes it a pressure vessel when gas forms. A mandrel supports the electrode assembly and keeps a path open for gas; the CID vent disk, domed toward the electrodes, turns convex as the pressure rises and disconnects the circuit, then its scored annulus ruptures to vent; the PTC switch is a conductive polymer whose resistance rises greatly when hot (Finegan 2018). 5. Tabless 4680: In the tabless 4680 design the uncoated edge of the electrode serves as the tab, joined to a multi-contact case bottom: this lowers the cell’s impedance and heat, and dropping the tabs together with the larger cell raises the energy density by 16% (Liu 2021). 6. Filling, formation, aging: The enclosure is filled with electrolyte before the final seal; the cell is charged to a low voltage (e.g. 1.5 V) to protect the copper current collector, rested for wetting and cycled at a low rate such as C/20, then faster, so a stable SEI forms on the anode. The gas is let out, the cells age on shelves and are degassed again before the final seal. Formation and aging take up to 3 weeks and 32.16% of the manufacturing cost; one protocol cycling between 3.9 and 4.2 V took about 14 h, 8.5 times faster (Liu 2021).

**What are the starting materials and the product?** Starting materials: Coated, calendered and slit electrodes, PP or PE separators, tabs, cans or pouch foil and electrolyte. Product: Formed and aged cylindrical, prismatic and pouch cells.

**Which papers is “Building and forming a battery cell” based on?** Liu, Zhang, Wang & Wang, “Current and future lithium-ion battery manufacturing”, iScience 2021 (doi:10.1016/j.isci.2021.102332); Katz & Cobb, “High-viscosity phase inversion separators for freestanding and direct-on-electrode manufacturing in lithium-ion batteries”, ACS Appl. Mater. Interfaces 2024 (doi:10.1021/acsami.4c09342); Stravova et al., “Comprehensive study of rapid capacity fade in prismatic Li-ion cells with flexible packaging”, Sci. Rep. 2024 (doi:10.1038/s41598-024-77673-3); Condon et al., “A dataset of over one thousand computed tomography scans of battery cells”, Data Brief 2024 (doi:10.1016/j.dib.2024.110614); Finegan et al., “Identifying the cause of rupture of Li-ion batteries during thermal runaway”, Adv. Sci. 2018 (doi:10.1002/advs.201700369).

**Can I edit the “Building and forming a battery cell” template?** Yes. Open it in the LabCanvas editor: all 45 layers are editable, including 6 generated objects (structures, plots, equipment) with their own settings. Change the text, colours and layout, then export PNG, TIFF, SVG or PDF.

**Do I need an account to use this template?** Not to view it here. To open and edit it, sign in to LabCanvas or create a free account (the free plan keeps up to 3 designs). Downloading the figure is part of LabCanvas Pro (US$19 a month or US$199 a year).