Single-bright foil
One bright and one matt face, the result of rolling two foils together in the final pass. The most economical form for 12 µm and above.
Battery materials
Aluminium Foil for Lithium-Ion Batteries: Grades and Quality Limits
Lithium-ion cells use a thin, hard aluminium foil, usually 10 – 16 µm thick in H18 temper, as the current collector for the cathode. The grade and quality of that foil decide how well the electrode coats, how much it stretches in calendering and how reliably the cell carries current. This guide compares 1050, 1060, 1070, 1235, 1100 and 8011 battery foil and sets out the thickness, strength, pinhole and flatness limits buyers specify. Metline supplies plain and coated battery foil to cell makers worldwide.
- Alloys
- 1050 · 1060 · 1070 · 1235 · 1100 · 8011
- Temper
- H18 (full hard)
- Thickness
- 8 – 20 µm
- Surfaces
- Plain, double-bright, carbon-coated
Why the cathode uses aluminium foil
The current collector carries electrons between the active material and the cell terminal, and gives the coated electrode its mechanical backbone. It has to be thin, conductive, strong enough to survive coating and calendering, and electrochemically stable at the cathode potential.
Aluminium suits the cathode because it forms a passive film that stays stable at the high potentials of cathode materials such as NMC, NCA, LFP and LCO (around 3 – 4.5 V versus lithium). It cannot be used on the anode side, where it would alloy with lithium at low potential; copper foil is used there instead. Aluminium also costs far less than copper and has about 30 % of its density, which matters when a cell contains square metres of foil.
Typical EV and energy-storage cathode foils are 12 – 16 µm thick. Consumer cells have moved to 10 – 12 µm, and development work targets 8 µm and below, which pushes up the strength and pinhole requirements the foil must meet.
Choosing a battery foil grade
| Grade | Al content | Character | Typical use |
|---|---|---|---|
| 1070 | ≥ 99.70 % | Highest conductivity, lowest strength | Cells where conductivity and clean surface matter most |
| 1060 / 1050 | ≥ 99.60 % / ≥ 99.50 % | Balanced conductivity and strength | General power and storage cathode foil |
| 1235 | ≥ 99.35 % | Easy to roll thin with few pinholes | Very common for 10 – 16 µm cathode foil |
| 1100 | ≥ 99.00 %, 0.05 – 0.20 Cu | Higher strength from copper | Thin foils that must survive high-tension coating lines |
| 8011 | Al-Fe-Si | Higher strength, slightly lower conductivity | Thin, high-strength foils and some carbon-coated substrates |
Purity and strength pull in opposite directions. 1070 conducts best but is softest; 1100 and 8011 are stronger because copper or iron-silicon particles harden the foil, at a small cost in conductivity. For most cells the difference in conductivity is not the limiting factor (the foil resistance is tiny next to the electrode), so many makers choose the grade that rolls thinnest with the fewest pinholes and breaks least on the coater. 1235 and 1060 are the common compromise; higher-strength grades take over as foil gets thinner.
Chemical composition limits (wt %, max unless range)
| Element | 1235 | 1050 | 1060 | 1070 | 1100 | 8011 |
|---|---|---|---|---|---|---|
| Si | Si + Fe 0.65 | 0.25 | 0.25 | 0.20 | Si + Fe 0.95 | 0.50 – 0.90 |
| Fe | — | 0.40 | 0.35 | 0.25 | — | 0.60 – 1.00 |
| Cu | 0.05 | 0.05 | 0.05 | 0.04 | 0.05 – 0.20 | 0.10 |
| Mn | 0.05 | 0.05 | 0.03 | 0.03 | 0.05 | 0.20 |
| Mg | 0.05 | 0.05 | 0.03 | 0.03 | — | 0.05 |
| Zn | 0.10 | 0.05 | 0.05 | 0.04 | 0.10 | 0.10 |
| Ti | 0.06 | 0.03 | 0.03 | 0.03 | — | 0.08 |
| Al | 99.35 min | 99.50 min | 99.60 min | 99.70 min | 99.00 min | Remainder |
Registered limits from the Aluminum Association / EN 573-3. Each coil is certified with its actual analysis.
Tensile strength and elongation of H18 battery foil
Battery foil is supplied full-hard (H18) because hard foil resists wrinkling and stretching on the coating line. Battery-foil specifications such as GB/T 33143 set minimum tensile strength and elongation by grade and thickness band; the figures below summarise the typical minimum levels for 10 – 20 µm foil.
| Grade (H18) | Tensile strength, typical minimum | Elongation, typical minimum |
|---|---|---|
| 1070 | ≈ 175 – 185 MPa | ≈ 2 % |
| 1060 / 1050 | ≈ 185 – 190 MPa | ≈ 2 – 3 % |
| 1235 | ≈ 175 – 185 MPa | ≈ 2 % |
| 1100 | ≈ 220 – 230 MPa | ≈ 1 – 3 % |
| 8011 | ≈ 180 MPa | ≈ 1 – 2 % |
Two properties matter beyond the room-temperature number. First, strength after drying: electrodes are dried at around 100 – 150 °C, which softens pure aluminium foil slightly, so high-throughput lines prefer grades that keep their strength. Second, elongation: during calendering the coated electrode is compressed hard, and foil with too little elongation tears at the edges or around the uncoated tab area.
Thickness, width, pinhole and flatness limits
Battery foil is ordered to precision classes. The values below show typical normal, high and ultra-high precision levels used in battery-foil specifications.
| Parameter | Normal | High precision | Ultra-high precision |
|---|---|---|---|
| Thickness tolerance | ± 5 % of T | ± 4 % of T | ± 3 % of T |
| Surface density (areal weight) tolerance | ± 5 % | ± 4 % | ± 3 % |
| Width tolerance (plain foil) | ± 1.0 mm | ± 0.5 mm | ± 0.5 mm |
| Edge burr | ≤ 150 µm | ≤ 100 µm | ≤ 50 µm |
| Wave height over 1 m span | ≤ 5.0 mm | ≤ 3.0 mm | ≤ 2.0 mm |
| Thickness | Max pinholes per m², normal | High precision | Ultra-high precision |
|---|---|---|---|
| ≤ 10 µm | 30 | 20 | 15 |
| > 10 – 13 µm | 15 | 10 | 6 |
| > 13 – 15 µm | 10 | 5 | 3 |
| > 15 – 20 µm | 3 | 0 | 0 |
- Wettability: surface tension of at least 32 dyn/cm by dyne pen, so the slurry spreads evenly
- Cleanliness: no oil stains, oil odour or rolling residues; uniform colour without bright lines, mottling or creases
- Coil build: tightly wound, flat end faces, telescoping within ± 1 mm, core width at least the foil width
- Splices: clearly marked at both coil ends, with the count stated on the label
Plain, double-bright and coated foils
Double-bright foil
Both faces bright, rolled singly. More uniform surface on both coated sides; used for thinner and premium foils.
Carbon-coated foil
A thin conductive carbon primer (typically 0.3 – 2 g/m²) improves adhesion and lowers interface resistance, especially with LFP. See carbon-coated aluminium foil.
Modified and porous foils
Etched, perforated or specially coated foils for high-rate or special cells. See modified battery foil.
Pouch packaging foil
A different product: soft 8021 or 8079 foil laminated into the pouch film as a moisture barrier. See 8021 pouch foil.
Coil formats
Widths up to about 1,600 mm, slit to order; cores of 76.2 or 152.4 mm (3 or 6 inch) and coil outer diameter by agreement.
Specifying battery foil: common mistakes
- Specify precision class, not just thicknessA 12 µm foil at ± 5 % and at ± 3 % behave very differently on a high-speed coater. State the thickness, areal-weight and width classes you need.
- Match strength to line tension and foil gaugeMoving to 10 µm on the same line often requires a stronger grade such as 1100 or 8011, not just thinner 1235.
- Test wettability on arrivalDyne level drops with storage time and poor packaging; check it on receipt and use foil in first-in, first-out order.
- Control storageKeep coils sealed in their moisture-barrier packing, away from temperature swings that cause condensation and white oxidation spots.
- Ask for full traceabilityCoil number, cast number, thickness and pinhole results on the certificate let you trace any cell-level defect back to the foil.
References and standards
- GB/T 33143 – Aluminium and aluminium alloy foil for lithium-ion batteries
- EN 546 – Aluminium and aluminium alloys: Foil (parts 1 – 4)
- ASTM B479 – Standard Specification for Annealed and Non-Annealed Aluminum and Aluminum-Alloy Foil
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits (Teal Sheets)
- EN 573-3 – Chemical composition and form of wrought products
Lithium-ion battery aluminium (aluminum) foil: FAQ
Why is aluminium foil used on the cathode and copper on the anode?
Aluminium stays passive at the high cathode potential but alloys with lithium at the low anode potential. Copper is stable at the anode but would oxidise at the cathode, so each electrode uses the metal that is stable at its potential.
What thickness is lithium-ion battery aluminium foil?
Most cathode foil is 10 – 16 µm. EV and storage cells commonly use 12 – 15 µm; consumer cells 10 – 12 µm; development cells go down to 8 µm.
Which is better for battery foil, 1235 or 1060?
Both are widely used. 1060 has slightly higher purity and conductivity; 1235 rolls very thin with low pinhole counts. The choice usually depends on the cell maker's qualified material and line tension.
Why is battery foil supplied in H18 temper?
Full-hard foil resists stretching and wrinkling under coating-line tension and keeps its flatness through drying and calendering.
How many pinholes are acceptable in battery foil?
It depends on thickness and precision class. For 13 – 15 µm foil, typical limits are 3 – 10 per m²; foil over 15 µm is often specified with zero pinholes at the higher classes.
Can Metline supply carbon-coated battery foil?
Yes. Metline supplies plain single- and double-bright battery foil and carbon-coated foil, slit to width, with certificates of chemistry, thickness and tensile results.
Sourcing cathode foil for battery production?
Send the grade, thickness, width, surface type and volume. Our team will reply with availability, test data and a delivered price.
