1 / 1
Battery aluminum foil differs from conventional aluminum foils due to its strict performance requirements tailored to battery operating conditions. Its key characteristics are as follows:
The aluminum content typically exceeds 99.9% (3N) and can reach up to 99.99% (4N) for high-end power batteries. High purity minimizes impurity elements (such as Fe, Si, Cu) that could cause side reactions in the battery, ensuring electrochemical stability.
Common thickness ranges from 4μm to 20μm, with 6μm, 8μm, and 12μm being the most widely used specifications. The thickness deviation is controlled within ±0.3μm to ensure uniform current distribution and avoid local overheating.
The electrical conductivity is ≥35 MS/m, which reduces the internal resistance of the battery and improves charge-discharge efficiency. High conductivity is particularly crucial for high-rate discharge scenarios like NEVs.
It has high tensile strength (≥150 MPa for 8μm foil) and good elongation (≥3%), enabling it to withstand the stress of electrode coating, rolling, and battery cycling without cracking or breaking.
The surface roughness (Ra) is controlled between 0.1μm and 0.5μm, ensuring strong adhesion with positive electrode active materials (e.g., lithium cobalt oxide, lithium iron phosphate) and preventing active material shedding during cycling.
It remains stable in the high-potential environment of the lithium-ion battery positive electrode (3.0-4.5V vs. Li/Li⁺) without undergoing oxidation or dissolution, ensuring long battery cycle life.
The production of battery aluminum foil is a high-precision process with strict control over each step to ensure performance consistency. The main steps are as follows:
As the core positive current collector of lithium-ion batteries, battery aluminum foil is widely used in various fields driven by the rapid development of new energy industries:
In lithium-ion battery positive current collectors, battery aluminum foil has irreplaceable advantages compared to alternative materials such as copper foil and stainless steel foil:
| Alternative Material | Advantages of Battery Aluminum Foil | Key Reason |
|---|---|---|
| Copper Foil | Lower cost (about 1/3 of copper foil), stable in high-potential environments, lighter weight | Copper foil is prone to oxidation at high potentials (positive electrode), while aluminum foil forms a stable oxide film for protection; aluminum has lower market price than copper. |
| Stainless Steel Foil | Better conductivity (35 MS/m vs. 15 MS/m of stainless steel), lighter weight (density 2.7g/cm³ vs. 7.9g/cm³ of stainless steel), lower internal resistance | Stainless steel has high resistivity, which increases battery internal resistance; its high density reduces battery energy density. |
| Titanium Foil | Much lower cost (about 1/10 of titanium foil), easier processing, and mature industrial chain | Titanium foil is expensive and difficult to produce in ultra-thin specifications, making it unsuitable for large-scale battery applications. |
Detail1
Precision Foil Roll
Slit Foil Detail
The common thickness range for battery aluminum foil is between 4μm and 20μm. The most widely used specifications in the market are 6μm, 8μm, and 12μm, depending on the specific power or energy density requirements of the battery.
High purity (typically 99.9% to 99.99%) minimizes the presence of impurity elements like iron (Fe), silicon (Si), and copper (Cu). This level of purity is vital to prevent harmful electrochemical side reactions inside the battery and maintain stability.
Battery aluminum foil is widely utilized as the positive current collector in power batteries for New Energy Vehicles (NEVs), stationary and portable Energy Storage Systems (ESS), lightweight consumer electronics (like smartphones and laptops), and specialized aerospace or medical equipment.
Aluminum foil is chemically stable under the high-potential conditions of the positive electrode, whereas copper foil would oxidize. Additionally, aluminum is lighter, has high electrical conductivity, and is about one-third the cost of copper.
Surface roughness is maintained between 0.1μm and 0.5μm to ensure strong physical adhesion between the foil and the positive active material coatings. Adequate roughness prevents the active material from shedding during repeated expansion and contraction cycles.
High tensile strength (at least 150 MPa for an 8μm thickness) combined with a good elongation rate (above 3%) allows the foil to survive continuous high-speed mechanical tension during coating, rolling, slitting, and battery cycling without tearing.
