3003 (Al-Mn)
The standard battery-shell alloy. About 1.0 – 1.5 % manganese raises strength by roughly 20 – 30 % over pure aluminium while keeping excellent drawability and laser weldability. Used in O, H12 and H14 for most prismatic cans and covers.
Guide · Battery cell cases
1050, 3003 & 3005 Aluminium Coil for Power Battery Shells
Prismatic lithium-ion cells are housed in deep-drawn aluminium cans, and most of those cans start as 3003 coil, with 1050 and 3005 used where conductivity or extra strength matter. The strip must draw deep without tearing or earing, hold a tight thickness tolerance and laser weld to the cover without porosity. This guide sets out the grades, properties and checks that battery-shell makers specify.
- Alloys
- 1050, 3003, 3005
- Tempers
- O, H12, H14
- Thickness
- About 0.6 – 3.0 mm
- Process
- Deep drawing, laser welding
Why battery shells are made of aluminium
A prismatic cell shell is a thin-walled rectangular can, open at one end, that contains the electrode stack and electrolyte. A cover plate carrying the terminals and safety vent is laser welded on top. Aluminium has largely replaced steel for this part because it saves weight in every cell of the pack, conducts heat out of the cell, does not rust and welds well with lasers.
The shell is typically formed from flat strip in several deep-drawing (or drawing and ironing) stages, sometimes after an impact-extrusion step, and then trimmed, cleaned and inspected. Every one of those steps puts demands on the coil: uniform thickness so the wall does not thin locally, a fine and even grain so the can does not orange-peel or ear, a clean surface for welding, and consistent properties from coil to coil so the press line can run without constant adjustment.
Non-heat-treatable alloys are used because they keep their properties after the welding heat and because their strength can be tuned by cold work (the H tempers). Heat-treatable 6xxx alloys and magnesium-rich 5xxx alloys are generally avoided for cans: 5xxx alloys tend to produce porosity in laser welds as magnesium vaporises, and 6xxx alloys are prone to weld cracking without filler.
1050 vs 3003 vs 3005 for battery shells
1050 (99.5 % Al)
Highest conductivity and ductility of the three. Used for very deep draws, inner lining parts and covers where electrical and thermal conductivity matter more than strength.
3005 (Al-Mn-Mg)
Adds 0.2 – 0.6 % magnesium to 3003 for higher strength and stiffness, allowing thinner walls. The magnesium slightly increases laser-weld sensitivity, so weld parameters need confirming.
The choice usually comes down to wall thickness and cell size. Large-format cells with thin walls need the strength of 3003-H14 or 3005 to resist swelling pressure, while small cells or very deep draws favour softer O-temper 3003 or 1050. Many shell makers buy O temper for the drawing stages, because the cold work of drawing itself hardens the can wall.
Chemical composition (wt %, maximum unless a range)
| Element | 1050 | 3003 | 3005 |
|---|---|---|---|
| Silicon (Si) | 0.25 | 0.6 | 0.6 |
| Iron (Fe) | 0.40 | 0.7 | 0.7 |
| Copper (Cu) | 0.05 | 0.05 – 0.20 | 0.30 |
| Manganese (Mn) | 0.05 | 1.0 – 1.5 | 1.0 – 1.5 |
| Magnesium (Mg) | 0.05 | — | 0.20 – 0.6 |
| Chromium (Cr) | — | — | 0.10 |
| Zinc (Zn) | 0.05 | 0.10 | 0.25 |
| Titanium (Ti) | 0.03 | — | 0.10 |
| Aluminium (Al) | 99.50 min | Remainder | Remainder |
Registered Aluminum Association limits, matching EN 573-3. Battery-grade coil is often produced to tighter internal limits on Fe and Si to control grain size and earing; agree these with the supplier if your process is sensitive.
Mechanical properties by temper
Values below are the standard sheet ranges from EN 485-2 for thin gauges. Battery-shell specifications commonly narrow the tensile band and set elongation and earing limits so that every coil draws the same way.
| Alloy and temper | Tensile strength (MPa) | 0.2 % yield (MPa, min) | Typical use in battery shells |
|---|---|---|---|
| 1050 O | 65 – 95 | 20 | Very deep draws, lining parts |
| 1050 H14 | 105 – 145 | 85 | Covers, flat conductive parts |
| 3003 O | 95 – 135 | 35 | Multi-stage deep-drawn cans |
| 3003 H12 | 120 – 160 | 90 | Moderate draws, higher can stiffness |
| 3003 H14 | 145 – 185 | 125 | Covers and shallow-drawn cans |
| 3005 O | 115 – 165 | 45 | Thin-wall cans needing more strength |
Physical properties (3003)
- Density
- 2.73 g/cm³
- Thermal conductivity (O)
- About 190 W/m·K
- Electrical conductivity (O)
- About 50 % IACS
- Melting range
- About 640 – 655 °C
Sizes and tolerances for battery-shell coil
Typical supply range
- Thickness
- About 0.6 – 3.0 mm (1050 to about 1.6 mm, 3005 to about 2.0 mm)
- Width
- Slit coil, typically 100 – 2000 mm to suit the press
- Form
- Coil, slit strip or cut sheets / blanks
- Surface
- Mill finish, degreased; free of scratches, roll marks and oil stains
- Standards
- ASTM B209, EN 485 / EN 573-3, or the cell maker’s specification
General-purpose sheet standards allow wider thickness bands than a deep-drawing press can tolerate. Battery-shell coil is therefore usually ordered to tighter agreed tolerances. The table shows a typical tightened specification; your drawing or supplier agreement takes precedence.
| Thickness (mm) | Typical agreed tolerance |
|---|---|
| 0.60 – 2.00 | ±0.02 mm |
| > 2.00 – 3.00 | ±0.03 mm |
| > 3.00 – 4.00 | ±0.04 mm |
Width tolerance on slit coil is typically about ±0.5 mm for narrow strip and ±1.5 mm for wider coil. Also specify coil inner diameter, maximum coil weight and edge condition (burr-free slit edges), since burrs can crack during drawing.
Laser welding the cover to the shell
The cover-to-can seam is the most critical joint in a prismatic cell: it must be hermetic for the life of the battery. Fibre and disc lasers weld 1xxx and 3xxx alloys well, but results depend on the material as much as on the laser.
| Factor | Effect on weld quality | What to specify |
|---|---|---|
| Alloy | 1050 and 3003 weld most consistently; 3005 slightly more sensitive because of Mg | Match alloy to the weld procedure qualified for the cell |
| Surface oil and oxide | Cause porosity and spatter | Degreased surface; controlled storage to limit oxide growth |
| Hydrogen content | Dissolved hydrogen forms pores in the weld | Melt treated with degassing and filtration |
| Thickness variation | Changes penetration depth around the seam | Tight thickness tolerance on can and cover |
| Fit-up | Gaps cause underfill or blow-holes | Can and cover dimensional tolerance |
Cell makers usually test weld acceptance by checking the rate of weld-pool defects, porosity, cracks and spatter on trial welds, followed by helium leak testing of finished cells. Ask for sample coil to run this trial on your own equipment before approving a new material source.
Surface treatment of finished shells
- Insulating film or blue film: the most common finish; a polymer film wrapped or laminated over the can to insulate cells from each other
- Powder coating: electrostatic powder baked into a continuous film for insulation and corrosion resistance
- Electrophoretic (e-) coating: thin, uniform coating that reaches edges and corners well
- Ceramic or plasma-electrolytic coatings: hard, insulating oxide layers for demanding designs, at higher cost
Coating adhesion depends on the cleanliness of the drawn can, so the coil surface and the drawing lubricant should be chosen with the later cleaning and coating steps in mind.
References and standards
- ASTM B209 – Standard Specification for Aluminum and Aluminum-Alloy Sheet and Plate
- EN 485-2 – Aluminium and aluminium alloys: sheet, strip and plate, mechanical properties
- EN 573-3 – Chemical composition and form of wrought products
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits
Aluminium (aluminum) coil for battery shells: FAQ
Which aluminium alloy is best for prismatic battery shells?
3003 is the most widely used, because it balances drawability, strength and laser weldability. 1050 suits very deep draws and conductive parts, and 3005 is chosen when thinner, stronger walls are needed.
Which temper should I order for deep drawing?
O temper is usual for multi-stage deep drawing, because the drawing operation work-hardens the wall. H12 or H14 is used for covers and shallow parts that need more stiffness as supplied.
Why are 5xxx alloys not used for battery cans?
Magnesium vaporises in the laser weld pool and tends to cause porosity and spatter, which threatens the hermetic seal. 1xxx and 3xxx alloys give more consistent welds.
What thickness tolerance is needed?
Tighter than general sheet standards. A typical agreed tolerance is ±0.02 mm for 0.6–2.0 mm strip, because thickness variation changes wall thinning in drawing and penetration in welding.
Does Metline make battery shells?
No. Metline supplies the aluminium coil, strip and blanks in 1050, 3003 and 3005, slit to width with mill test certificates. The drawing, welding and coating of shells are done by cell and component manufacturers.
Need coil for battery shells?
Send alloy, temper, gauge, width and volume. We will propose matching material, arrange samples and quote delivered to your plant.
