18650 barley paper (also known as "fish paper") is a durable, heat-resistant, and electrically non-conductive insulation material. It is primarily used to cover the positive terminal ring of 18650 lithium-ion cells, preventing the nickel strips from shorting against the metal can of the battery.
Thickness: Common thicknesses range from 0.1 mm to 0.3 mm, 0.2 mm being the most popular for battery building.
Dielectric Strength: High voltage tolerance, typically breaking down only at >5 kV.
Temperature Resistance: Rated for continuous operation up to 130°C (Class B).