What Is Aluminum Foil Electrical Conductivity

In the industrial sector, the aluminum foil jumbo roll, thanks to its advantages such as lightweight, corrosion resistance, and easy processing, has become a fixture in the electronics, energy, and packaging industries. Electrical conductivity, as a core metric for measuring a material's ability to conduct electricity, directly determines the value of aluminum foil in electrical conductivity-related applications.

To determine the electrical conductivity of aluminum foil, a reference standard is first needed. Industry typically uses the International Annealed Copper Standard (IACS), defining the conductivity of annealed pure copper as 100% IACS.

According to data, the electrical conductivity of pure aluminum (99.99% purity or above) is approximately 60%-65% IACS (35-38 S/m at 20°C). While this is significantly lower than pure copper, it is significantly higher than most alloy materials (for example, ordinary steel has a conductivity of only about 3%-5% IACS, and stainless steel is even lower). The conductivity of battery aluminum foil in actual use will fluctuate slightly due to processing techniques (such as rolling and annealing) and alloy composition:

Annealed aluminum foil: After high-temperature annealing, the aluminum foil's internal grains become more uniform, internal stress is reduced, and its conductivity approaches that of pure aluminum, typically reaching 58%-63% IACS.

Hard aluminum foil: Unannealed or lightly processed aluminum foil experiences increased resistance due to lattice distortion, resulting in a 10%-15% decrease in conductivity, typically to 45%-55% IACS.

Notably, aluminum's density is only about one-third that of copper. When calculated based on "conductivity per unit weight," aluminum's advantages are further highlighted—at the same weight, aluminum's conductivity is approximately twice that of copper.

The electrical conductivity of aluminum foil is essentially determined by its purity and alloying element content. Alloying elements (such as magnesium, silicon, manganese, and copper) form solid solutions or intermetallic compounds with aluminum, hindering the directional movement of electrons and thus reducing conductivity. Therefore, high-conductivity aluminum foil is almost exclusively found in pure and low-alloy aluminum series, such as 1000 aluminum foils.

1235 aluminum foil: aluminum content is approximately 99.35%, iron content is 0.3%-0.6%, and silicon content is ≤0.12%. Its electrical conductivity is approximately 58%-62% IACS, and it also exhibits good ductility.

1100 aluminum foil: Aluminum content ≥99.0%, iron + silicon content ≤1.0%, conductivity approximately 55%-58% IACS. Compared to 1235, it offers better processing performance and a lower price. It is commonly used in cost-sensitive applications such as conductive gaskets for low-voltage electrical appliances and electrolytic capacitor casings, where conductivity requirements are slightly lower.

1060 aluminum foil: With an aluminum content of ≥99.6% and extremely low impurity levels, it has a conductivity of 62%-65% IACS, making it one of the most conductive grades in the 1 series. However, this high purity also results in lower strength and increased deformation. It is primarily used in high-end applications such as conductive connections for precision electronic components and as laboratory electrode materials.

Lithium battery current collectors are a core application for high-conductivity aluminum foil. In lithium-ion batteries, aluminum foil is used as the current collector for the positive electrode (copper foil for the negative electrode). With a conductivity of 58%-62% IACS, 1235 battery aluminum foil efficiently collects the current generated by the positive electrode and transmits it to the external circuit. Currently, a new energy vehicle's power battery consumes approximately 20-50 kilograms of aluminum foil. As electric vehicle penetration increases, demand for highly conductive aluminum foil continues to grow.