Applications, Technical Requirements, and Development Trends of Aluminum Foil in Lithium Batteries

Applications of Aluminum Foil in lithium batteries

• The positive current collector of lithium-ion batteries. Aluminum foil current collectors exhibit superior electrochemical performance and morphological structural stability compared to copper foil under identical conditions. As a cathode current collector in lithium-ion batteries, aluminum foil effectively mitigates electrolyte-induced corrosion of the cathode and stabilizes battery polarization behavior 

• The barrier layer for the soft-pack packaging materials of lithium-ion batteries. Aluminum foil exhibits exceptional water and oxygen barrier properties. Physically, it effectively prevents external water and oxygen from penetrating into the battery cell interior. Additionally, as a metallic material, aluminum foil possesses sufficient elongation and tensile strength to meet the requirements of cold stamping processes. It is highly suitable for serving as the barrier layer in soft-pack packaging materials, hence its widespread application.                                                                                                                                                                                                                                                                           

• Other Applications of Aluminum Foil in Lithium-Ion Batteries. To reduce battery weight, some square lithium-ion batteries employ aluminum shells instead of stainless steel ones; the tab electrodes of lithium-ion batteries typically utilize 0.1 mm-thick aluminum foil, with the blank areas of carbon-coated aluminum foil commonly utilized for electrode fabrication or directly serving as welding points for tabs.                                                                                                                                                                                                                                               

Quality Standards for Battery Aluminum Foil

Development Direction of Battery Foil (Modification Treatment of Aluminum Foil)

• Carbon-coated aluminum foil. Surface carbon coating is one of the primary modification methods for aluminum foil. Carbon-coated aluminum foil is fabricated by compounding nanometer-scale conductive graphite with aluminum foil and falls into two categories based on solvent type: aqueous (using pure water as the dispersing medium) and oil-based (e.g., NMP). This material forms a double-sided conductive carbon layer (approximately 2 µm thick) on the aluminum foil surface via coating processes such as roll-to-roll deposition. By increasing the surface roughness of the current collector, reducing contact resistance between positive/negative electrode materials and the current collector, enhancing adhesion of active materials while minimizing binder usage, it prevents aluminum foil oxidation-corrosion, reduces battery polarization, and improves cell pack consistency.                                                                                                                                                                                                                                                               
• New Composite Aluminum Foil. The substitution of traditional metal current collectors with lighter materials represents a key research direction for enhancing battery energy density. This approach is based on the fact that energy density improvement is closely related to material weight; while aluminum and copper foils, as current collector materials, have high densities but contribute no capacity during charging and discharging. Polymer-based composite metal current collectors offer significant advantages in improving both the safety of lithium-ion batteries and their energy density. Current composite aluminum foils are typically fabricated via evaporation processes using aluminum-coated composite films with polyethylene terephthalate (PET) or similar substrates.