In-depth Analysis of the Composite Aluminum Foil Industry: Industrialization Accelerates, Market Size Expected to Exceed 24 Billion by 2026

Sa 2025, the composite aluminum foil industry experienced explosive growth, flourishing across the entire chain from equipment to application. This not only highlights the inevitable trend of composite aluminum foil replacing traditional foil but also outlines a golden industry chain encompassing equipment, foil materials, and base films. As a “new favorite” born from the trillion-yuan battery market, what exactly is driving this industry transformation, and how will it reshape the industrial landscape?

Technological Revolution: Composite Aluminum Foil Solves the Core “Energy-Safety” Dilemma in Batteries

Traditional aluminum foil has long been stuck in a dilemma for power battery applications: the 12μm thick foil not only accounts for a significant portion of weight, hindering improvements in energy density, but also, due to its tendency to produce large burrs after puncturing, becomes a key hidden danger triggering battery thermal runaway. The composite aluminum foil, with its “PET base film + metal aluminum layer” sandwich structure, precisely tackles these two industry pain points, emerging as a core breakthrough for power battery upgrades.

(1) Ang “Lightweight Code” for Energy Density Enhancement

The lightweight advantage of composite aluminum foil is essentially a dual innovation in material structure and process, directly driving a leap in battery energy density:

• Thinner, Performance Doubled:​ 8μm composite aluminum foil (6μm PET + 2μm aluminum layer) is 58% lighter compared to 12μm traditional foil, directly boosting battery energy density by 4.2%. Taking a conventional power battery with 150 Wh/kg as an example, replacing it with composite aluminyo foil can elevate the energy density to 160 Wh/kg, significantly extending the range.
• Chemical Wisdom of Material Combination:​ The PET base film has a density of only 1.38 g/cm³, far lower than metal aluminum’s 2.7 g/cm³, offering a significant lightweight advantage. Meanwhile, the modified PET base film can withstand 130-140°C high temperatures, ensuring structural stability during battery operation while achieving weight reduction, preventing performance degradation due to high-temperature deformation.
• Corporate Evidence, Data Support:​ Patent data from BYD shows that using a composite structure of 4μm PP + 3μm aluminum on both sides, compared to 10μm traditional foil, can increase battery energy density by 2.6%. If used in conjunction with composite copper foil, the battery system energy density can be boosted by 6.1%, verifying the immense potential of composite aluminum foil for enhancing energy density.
• Technological Breakthroughs, Cost Reduction and Efficiency Improvement:​ Companies like Shanghai Lianjing have achieved cost reduction and safety upgrades for composite aluminum foil through three core technological innovations: functional film modification technology, high-temperature hot-press lamination process, and ultra-thin aluminum foil rolling technology, further promoting its industrial adoption.

(2) Ang “Thermal Fuse Mechanism” for Safety Performance Upgrade

Power battery safety is the bottom line for industry development. Composite aluminum foil, through its unique structural design, establishes a dual “active + passive” protection system, perfectly meeting the industry’s safety upgrade needs:

• Puncture Protection, Micro-level Innovation:​ Punctures in traditional foil produce burrs reaching millimeter-scale, easily causing internal short circuits. The metal aluminum layer in composite foil is only about 1μm. Once a puncture short circuit occurs, the metal layer melts rapidly like a fuse, creating a “point break” that effectively limits short-circuit current spread, reducing thermal runaway risk at the source.
• Active Defense Against Thermal Runaway:​ The polymer substrate (e.g., PET, PP) in composite aluminum foil melts and shrinks around 150°C, actively cutting off the internal current circuit, enabling early intervention in thermal runaway. Traditional foil lacks this active protection function, relying only on passive methods like increased thickness, which sacrifices energy density.
• Policy Drive, Demand Becomes Essential:​ The new EU ECE R100.03 regulation implemented in September 2025 adds 10 stringent safety tests, including fire resistance and mechanical shock, significantly raising the safety threshold for power batteries. With its excellent safety performance, composite aluminum foil has become a core solution for companies to meet the new requirements, further unleashing market demand.