Battery grade aluminum foil is used as the collector of lithium ion battery. Generally, the lithium ion battery industry uses rolled aluminum foil as the positive collector.
 
The rolled foil thickness ranges from 10 microns to 50 microns. Common pure aluminum foils for lithium batteries include 1060, 1050, 1145, 1235 and other alloy grades, with - O, h14, - H24, - H22, - h18 and other states.
 
Lithium batteries usually have two shapes: cylindrical and square. The battery adopts a spiral wound structure and is separated between the positive and negative electrodes with a very fine and highly permeable polyethylene film isolation material. The positive electrode includes a current collector composed of lithium cobalt oxide (or nickel cobalt lithium manganate, lithium manganate, lithium ferrous phosphate, etc.) and aluminum foil. The negative electrode is composed of a current collector composed of graphitized carbon material and copper foil. The battery is filled with organic electrolyte solution. In addition, it is also equipped with safety valve and PTC elements (some cylindrical use) to protect the battery from damage in abnormal state and output short circuit.


 
Battery grade aluminum foil quality requirements
 
The surface color of the first aluminum foil shall be uniform, clean and flat, without obvious roll marks, pitting, pinholes and corrosion traces;
 
The second aluminum foil surface is free of rolling defects such as creases, spots and bright lines;
 
Third, there is no color difference on the surface of aluminum foil;
 
The fourth surface is free of oil, serious oil smell and oil spots visible to the naked eye;
 
Fifth, the surface tension shall not be less than 32 dyne when tested with dyne pen;
 
 
Appearance requirements for battery grade aluminum foil
 
First, the winding tightness of aluminum foil roll is appropriate, the end face is flat and clean, and the edge is smooth;
 
Second, the staggered layer of aluminum foil shall not exceed ± 1.0mm;
 
Third, the width of the aluminum foil roll tube core is greater than or equal to the foil width. Generally, the length of the two ends of the tube core does not exceed the foil width by 5mm;
 
Fourth, the aluminum foil shall be wound in the center of the tube core;
 
Fifth, there are clear joint marks at the second end of the aluminum coil.
 
On the basis of fully considering the thermal conductivity, electrical conductivity and mechanical strength of aluminum foil, special blank is adopted and manufactured by high-precision imported rolling mill with on-line profile roll and Siemens control system in a clean dust removal plant environment  [ 2]   。
 
Features of battery grade aluminum foil:
 
1. Aluminum foil rolling mill equipment is equipped with advanced thickness automatic control system and shape automatic control system to realize accurate control of plate shape and thickness;
 
2. Select the aluminum foil blank, strictly control the hydrogen content, non-metallic slag content and grain size of the blank, and ensure the product quality from the raw materials;
 
3. Advanced on-line oil removal technology is adopted to ensure the cleanliness of aluminum foil on the basis of ensuring the mechanical strength of aluminum foil.