Battery aluminum foil is commonly used in lithium-ion batteries as a current collector, primarily for the cathode. It is responsible for collecting current and conducting it to the external circuit. Its thickness directly affects battery energy density and overall performance.
Our 9 micron double-sided bright battery aluminum foil is mainly used in premium battery products such as mobile phone batteries, 3C consumer batteries, and robot batteries. The ultra-thin foil helps make batteries thinner and increases energy density, while providing stable electrical conductivity and reliable performance during charging and discharging.
9μm battery aluminum foil is generally manufactured from high-purity, battery-grade aluminum. Common alloys include 1050, 1060, 1070, and 1235. High-purity aluminum slabs are processed through a complete battery-grade quality-control system, including online melt degassing, precision multi-pass cold rolling, vacuum annealing, clean-room slitting, and full online inspection.
The finished foil features very low pinhole levels, uniform thickness, a clean surface, and a well-balanced combination of tensile strength and elongation. It is suitable for high-speed coating, calendaring, slitting, and winding processes.
Battery Aluminum Foil Specifications
| Item | Specification |
| Product Name | Ultra-Thin 9 Micron Battery Aluminum Foil |
| Main Application | Cathode current collector and cathode electrode substrate for lithium-ion batteries |
| Standard Thickness | 9μm / 0.009mm |
| Available Thickness Range | 6μm, 7μm, 8μm, 9μm, 10μm, 12μm, 15μm, 16μm, etc. |
Common Alloys | 1235, 1070, 1060, or as confirmed according to technical requirements |
| Aluminum Purity | ≥99.6%, ≥99.7%, or ≥99.9%, depending on the battery chemistry and customer requirements |
| Electrical Conductivity | ≥61% IACS |
| Temper | Soft temper or supplied according to the customer's processing requirements |
| Supply Form | Jumbo rolls, slit coils, narrow strip coils, or customized coils |
| Width Range | Slit to customer requirements; common widths: 200mm–1700mm |
| Coil Inner Diameter | 76mm, 150mm, 200mm, 300mm, 500mm, 508mm, or customized |
| Surface Wettability | ≥32 dyn/cm, supporting adhesion of cathode slurry |
| Surface Roughness | Ra 0.20–0.40μm, helping maintain stable interfacial resistance |
| Typical Mechanical Properties | Tensile strength ≥170 MPa; elongation ≥1.5% |
Pinhole Control | High-magnification online optical inspection with strict micro-pinhole control |
| Coil Weight | Determined according to width, coil diameter, equipment load capacity, and customer requirements |
| Surface Condition | Clean, flat, free from oil contamination, obvious oxidation, dents, and severe scratches |
| Packaging | Vacuum moisture-proof and anti-static protection; export wooden cases or pallets |
| Application Industries | EV batteries, energy storage batteries, consumer electronics, new energy vehicles, power tools, etc. |
Key Advantages of 9μm Ultra-Thin Battery Aluminum Foil
1. Lightweight Design for Higher Cell Energy Density
Reducing current collector thickness is one of the most direct approaches to increasing battery energy density. Compared with thicker foil, 9μm aluminum foil reduces the proportion of inactive materials and allows more cathode active material to be loaded within the same electrode dimensions.
It is particularly suitable for high-specific-energy power cells, long-duration energy storage cells, and sodium-ion batteries.
2. Stable Electrochemical Compatibility
The high-purity aluminum substrate is subject to strict control of potentially harmful impurities such as Fe, Si, and Cu. It offers stable compatibility in high-voltage cathode environments and helps resist electrolyte corrosion and undesired side reactions.
This can help reduce self-discharge and support battery cycle life and storage stability. In sodium-ion battery systems, aluminum foil can potentially be used as a current collector for both cathodes and anodes, supporting sodium-ion battery industrialization routes.
3. Excellent Processability for High-Speed Production Lines
Ultra-thin foil is more susceptible to breakage and wrinkling during processing. Through optimized rolling processes and annealing conditions, we balance tensile strength and elongation to provide stable resistance to stretching and tearing.
The foil is compatible with high-speed coating machines, continuous calendaring, automatic slitting, and winding operations, helping reduce strip-break-related downtime.
4. High Surface Cleanliness
Produced in controlled clean production environments, the foil is designed to have low residual rolling oil, minimal dust, and no significant scratches, bright spots, or roller marks. Stable surface wettability supports uniform coating of cathode slurries, including LFP, NCM, and NCA materials.
This helps reduce risks such as powder shedding, exposed foil, and localized resistance abnormalities.
5. Strong Batch Consistency for Large-Scale Production
Full-width online thickness scanning and AI-assisted visual pinhole inspection are used during production. Each coil is individually identified and traceable. Mechanical properties, electrical conductivity, and surface characteristics are maintained with controlled variation between batches, helping overseas battery manufacturers stabilize formulations and production processes while reducing cell-consistency issues.
Typical Applications
Cathode current collectors for high-energy-density LFP and ternary lithium-ion power batteries
Lithium battery systems for utility-scale energy storage, residential storage, and commercial & industrial energy storage
Sodium-ion batteries, including applications using aluminum foil as both cathode and anode current collectors
Pouch, cylindrical, and prismatic cells, as well as high-end 3C consumer lithium batteries
Batteries for power tools, electric two-wheelers, and low-speed electric vehicles
Overseas battery-material trading, new-energy BOM supply, and battery R&D laboratory sample testing
Quality Control for Battery Aluminum Foil
Thickness and Flatness Control
Thickness variation in 9μm foil directly affects coating loading consistency, electrode density, winding structure, and cell performance. Online thickness measurement and closed-loop flatness control are applied to maintain longitudinal and transverse thickness consistency in accordance with applicable national standards or customer agreements.
Flatness defects such as wrinkles and loose edges are amplified in ultra-thin foil. Therefore, edge quality is strictly controlled during slitting.
Surface Cleanliness and Wettability
Residual oil on aluminum foil can significantly reduce cathode slurry adhesion, resulting in coating delamination or powder loss. The foil is cleaned and tested for surface wetting tension to ensure stable bonding with cathode slurries, including lithium iron phosphate and ternary cathode materials.
Surface roughness is also controlled within an appropriate range. Excessively smooth surfaces may increase the risk of cracking during slurry drying, while excessively rough surfaces can reduce coating uniformity.
Pinhole and Mechanical Uniformity Control
Pinholes in ultra-thin aluminum foil can contribute to battery self-discharge risk. Pinhole inspection and evaluation can be performed in accordance with the relevant requirements of GB/T 33143-2022.
Mechanical properties are sampled and tested by batch to ensure consistency between coils and within each coil, reducing the need for frequent process adjustments caused by incoming-material variation.
FAQ
Q1: What is the main difference between 9μm and 12μm battery aluminum foil? How should customers choose?
A: 9μm foil is thinner and can provide a higher energy-density potential, but it requires better tension control on the production line. It is suitable for power battery, energy storage, and sodium-ion battery projects focused on high specific energy.
12μm foil has greater mechanical strength and higher process tolerance, making it more suitable for conventional energy storage batteries and standard 3C battery cells. Customers with existing production lines should evaluate the tension capabilities of their coating and winding equipment before switching to 9μm foil.
Q2: Is pinhole control difficult for 9μm ultra-thin aluminum foil?
A: Yes. Pinhole control for ultra-thin foil is significantly more challenging than for thicker foil. We use full-width online optical pinhole inspection and grading systems. Coils are inspected and released according to battery-grade standards, while nonconforming coils are isolated to help ensure delivery quality.
Q3: Can you supply carbon-coated 9μm aluminum foil?
A: Yes. Single-sided or double-sided carbon-coated 9μm battery aluminum foil can be supplied. Carbon coating can help reduce interfacial contact resistance and improve rate performance, making it suitable for high-power and high-rate battery cells.
Q4: How are samples shipped, and what is the minimum order quantity?
A: Small coil samples are available for laboratory testing and pilot-scale validation. Production orders are subject to applicable MOQ requirements, which vary depending on foil width and specifications. Please contact us for confirmation.
Contact Us
For the latest FOB quotation, samples, technical data sheets, mechanical-property data, conductivity reports, or carbon-coated 9μm battery aluminum foil solutions, please send us your inquiry with the following details:
Required alloy and thickness
Required width
Coil inner diameter and target coil weight
Surface requirements, including wettability and roughness
Required quantity
Destination port and preferred Incoterms
We will provide a complete technical proposal, export quotation, and packaging solution promptly.