Carbon Coated Aluminum Foil

Carbon-coated aluminum foil is a functional composite material in which a uniform layer of conductive carbon material is coated onto the surface of high-purity aluminum foil. Carbon-coated aluminum foil is used to extend the service life of battery packs and is made by compounding nano conductive graphite with aluminum foil or copper foil. It is available in two types: water-based and oil-based.

Through a roll-to-roll coating process, this material forms a double-sided conductive carbon layer (approximately 2 µm thick) on the surface of the aluminum foil. It is mainly used as the positive current collector in lithium iron phosphate (LFP) power batteries and lithium-sulfur batteries.

By coating carbon materials (such as conductive carbon black, graphene, etc.) on the surface of the aluminum foil, carbon-coated aluminum foil significantly reduces the internal resistance of the battery, improves electron transport efficiency, and enhances adhesion between the active materials and the current collector. This helps reduce the amount of binder required and improves the battery's rate performance, cycle life, and safety.

Carbon-coated aluminum foil, also known as “carbon-coated foil” or “conductive-coated aluminum foil, ” is a composite foil formed by uniformly applying a layer of conductive carbon material (such as carbon black, graphene, carbon nanotubes, etc.) onto the surface of traditional aluminum-foil current collectors through specialized processes.

• Substrate: Aluminum foil with purity ≥ 99.9% (commonly alloys 1060, 1070, 1100, 1235), typically around 16 μm in thickness
• Coating: Carbon materials (carbon black, graphite, graphene, carbon nanotubes, etc.) combined with binders, with a thickness of 0.3–5 μm, single-sided or double-sided coating

Specifications of Carbon-Coated Aluminum Foil

Structure and Composition of Carbon Coated Aluminum Foil

• Substrate: Electronic-grade high-purity aluminum foil (typically 10–20 µm thick).
• Requirements: The surface must be clean, smooth, and possess excellent conductivity and mechanical strength.
• Coating: Conductive carbon layer (typically 1–4 µm thick).
• Conductive agents: Such as super conductive carbon black, acetylene black, graphene, VGCF, etc., providing a conductive network.
• Binders: Such as water-based acrylic resin, SBR latex, etc., to ensure strong adhesion between the carbon layer and the aluminum foil.
• Dispersants and other additives: Ensure slurry uniformity and stability.

Classification of Carbon Coated Aluminum Foil

• Water-based carbon coated aluminum foil: Uses water as the solvent, environmentally friendly and non-toxic, coating thickness 1–5 µm, widely used in consumer electronics and new-energy vehicle batteries.
• Oil-based carbon coated aluminum foil (45% market share): Uses organic solvents as the carrier, features dense coatings (3–8 µm), suitable for high-end applications such as aerospace.

Advantages of Carbon Coated Aluminum Foil

Compared with traditional bare aluminum foil, carbon coated aluminum foil provides multiple performance improvements:

Significantly reduces interfacial impedance

Issue: Positive electrode active materials (such as LFP and NCM materials) do not make sufficient contact with the smooth surface of bare aluminum foil, resulting in high contact resistance.

Solution: The carbon coating provides a three-dimensional conductive network, forming “surface contact” rather than “point contact” with active material particles, greatly reducing the contact resistance between the current collector and the active material.

Improved battery rate performance

Due to reduced interfacial impedance and smoother electron transport pathways, polarization is reduced during high-rate charging/discharging, voltage platforms remain more stable, and output power is higher.

Enhanced adhesion between active materials and the current collector

The micro-rough structure of the carbon coating increases the specific surface area, gripping the active materials like “glue, ” reducing the risk of active-material detachment during cycling and improving cycle life.

Protects aluminum current collector and prevents oxidation/corrosion

In high-voltage cathode materials (such as high-nickel NCM and LCO) and electrolyte environments, aluminum foil surfaces tend to form oxide films, increasing impedance or causing corrosion. The carbon coating acts as a physical barrier, effectively protecting the aluminum foil.

Improves battery consistency and yield rate

Enhances coating uniformity of electrode slurry, reducing performance variation caused by surface defects of the current collector and improving overall production yield.

Potential to reduce conductive-agent usage

Since the current collector itself exhibits excellent conductivity, the amount of conductive agent in the cathode slurry can be reduced, increasing the proportion of active material and contributing to higher energy density.

Applications of Carbon Coated Aluminum Foil

Carbon Coated Aluminum Foil (carbon-coated foil / coated conductive aluminum foil) is an advanced battery current collector widely used in the new-energy field to enhance interfacial conductivity, reduce internal resistance, and improve electrochemical stability. It performs exceptionally well in the following applications:

New-Energy Batteries (EV & ESS)

In power batteries and energy-storage systems, carbon coated aluminum foil significantly reduces electrode interface impedance, improving charging/discharging efficiency and cycle stability.

Solid-State Batteries

In solid-state systems, solid electrolytes typically have poor contact with metal foils. Carbon Coated Aluminum Foil improves interfacial wettability and contact area, enabling higher rate performance.

Flexible Electronic Devices

Carbon coated aluminum foil offers high conductivity and some degree of flexibility, suitable for wearable electronics and flexible energy-storage devices requiring lightweight and thin designs.

Key Application Scenarios for Carbon Coated Aluminum Foil

Carbon coated aluminum foil is not required in all batteries, but it provides significant value in the following battery types:

High-Rate Power Batteries

Suitable for devices requiring extremely high instantaneous discharge or fast charging, such as:

• Electric Vehicles (EV)
• Unmanned Aerial Vehicles (UAV)
• Power Tools
• Electric motorcycles and e-scooters

Carbon coated aluminum foil effectively reduces interface impedance and enhances 5C–10C high-rate performance.

Ultra-long Cycle Life Batteries

Suitable for applications with extremely high cycle-life requirements:

• Large-scale energy-storage power stations (ESS)
• Telecom base-station backup power
• UPS uninterruptible power systems

The carbon coating suppresses aluminum-foil corrosion and enhances electrode structural stability, significantly extending cycle life.

High Energy Density Cells

In consumer electronics using high-voltage cathodes, coated aluminum foil improves interfacial stability and reduces side reactions.

Cathode Systems with Poor Conductivity

Such as LFP (lithium iron phosphate) cells, which inherently have low conductivity, the use of Carbon Coated Aluminum Foil can significantly improve:

• Rate performance
• Initial charging efficiency
• Low-temperature performance

This is one of the fastest-growing application areas for carbon coated aluminum foil.

Selection of Carbon Coating Materials

The choice of carbon coating materials directly affects the conductivity, adhesion, corrosion resistance, and electrochemical stability of Carbon-Coated Aluminum Foil. It is a key factor influencing the performance of battery cathode current collectors. Common industrial carbon materials include:

Carbon Black

• Features: Stable conductivity, low cost, good dispersibility.
• Advantages: Forms dense and uniform carbon layers, improves interfacial conductivity, suitable for mainstream lithium-ion batteries.
• Applications: Widely used in power and energy-storage batteries.

Graphite

• Features: Layered structure with high electron mobility.
• Advantages: Greatly enhances conductivity and lubrication of the coating, making compaction more stable.
• Applications: Mid- to high-end power batteries, sodium-ion batteries using carbon coated foil.

Carbon Nanotubes (CNTs)

• Features: One-dimensional structure with extremely high conductivity and mechanical strength.
• Advantages: Builds a three-dimensional conductive network, reduces interfacial resistance, and improves cycle life.
• Applications: High-rate batteries and high-end energy-storage systems.

Graphene

• Features: Two-dimensional honeycomb structure, extremely high conductivity and strength.
• Advantages: Significantly improves electron/ion transport efficiency and interface stability.
• Applications: High-end power batteries and solid-state batteries using carbon coated foil.

Reduced Graphene Oxide (rGO)

• Features: Combines properties of graphene and graphene oxide, easy to disperse, lower cost.
• Advantages: Forms a continuous conductive layer, improves adhesion and corrosion resistance.
• Applications: Mid- to high-end lithium-ion batteries and energy-dense systems.

Manufacturing Processes of Carbon Coated Aluminum Foil

Mainly divided into two methods:

Transfer Coating Method

The carbon slurry is first coated onto a carrier and dried into a film, then transferred onto the aluminum foil via rolling.

• Advantages: Uniform coating, smooth surface.
• Disadvantages: Long process flow and higher cost.

Direct Coating Method

The prepared conductive carbon slurry is directly coated onto the aluminum foil using slot-die, micro-gravure, or other coating techniques, then dried and cured in an oven.

• Advantages: Simple process, lower cost, currently the mainstream method.
• Disadvantages: Requires strict control of slurry formulation and coating parameters; otherwise, issues such as streaks and uneven thickness may occur.

Properties of carbon coated aluminum foil substrate

Mechanical properties of carbon coated aluminum foil substrate

Carbon-Coated Aluminum Foil FAQ

What is the main function of carbon-coated aluminum foil?

• Reduce electrode interfacial contact resistance
• Enhance adhesion between active materials and aluminum foil
• Suppress anode surface corrosion
• Reduce polarization and improve rate performance
• Suppress lithium dendrite formation and improve battery safety
• Enhance cycle life and thermal stability

What materials are commonly used for the carbon coating?

Common materials include:

• Carbon Black: good conductivity and low cost
• Graphite Flakes: improve the stability of the conductive network
• Graphene: ultra-high conductivity and high mechanical strength
• Composite systems: for achieving optimal conductivity and adhesion

In which batteries is carbon-coated aluminum foil typically used?

Mainly used in:

• Power batteries (EV/HEV)
• High-rate batteries
• Lithium iron phosphate (LFP) batteries
• Ternary batteries (NCM/NCA)
• Polymer pouch cells
• Energy storage batteries (ESS)

What is the typical thickness of the carbon coating?

Common coating thickness:

• Single-sided: 1 μm
• Double-sided: 1 μm + 1 μm

Different manufacturers can customize coating thickness and coating weight based on application needs.

What aluminum grades are typically used as the substrate for carbon-coated aluminum foil?

Common aluminum foil substrates include:

1060, 1070, 1080, 1100, 1235

These grades offer high purity, good ductility, and stable electrochemical performance.

Can carbon-coated aluminum foil be coated on one side or both sides?

Both are possible:

• Single-sided coating: suitable for traditional stacking and winding processes
• Double-sided coating: improves overall conductivity and rate performance

What is the typical total thickness of carbon-coated aluminum foil?

Common total thicknesses:

• 18 μm (16 μm aluminum foil + 1 μm coating × single side)
• 20 μm (double-sided coating)

Other thicknesses can be customized.

Can the width of carbon-coated aluminum foil be customized?

Yes, it can.

Standard substrate width is 260 mm, coating width is about 230 mm, and can be customized according to the customer's winding equipment.

How does carbon-coated aluminum foil improve adhesion?

The carbon coating provides a rougher, higher-energy bonding surface while improving the surface polarity of the aluminum foil, allowing active materials to adhere more strongly. All products undergo ASTM D3359 adhesion testing.

By functionally upgrading the traditional current collector, carbon-coated aluminum foil effectively solves interfacial challenges in lithium batteries—especially on the cathode side. Although it is not an active material, it plays a critical “infrastructure” role in improving rate capability, cycle life, and safety. It has become an indispensable component in today’s high-performance lithium battery technologies.