Question 1

Why is adhesive strength so important in electrode coatings?

Accepted Answer

In lithium-ion batteries – currently the dominant battery type – the electrodes consist of active materials that are applied to metal foils (copper for the anode, aluminum for the cathode). These layers must adhere permanently and firmly, since mechanical stresses occur during the charging and discharging process: The materials expand, contract, and are subjected to thermal stress. If the adhesion is insufficient, the coating is at risk of coming loose, with consequences such as a loss of power, a drop in capacity or, in the worst case, a short circuit. Adhesion tests therefore not only help to ensure quality, but also prevent potential safety risks.

Question 2

How is adhesion strength tested?

Accepted Answer

Two methods have become established in practice:1.  Peel test : An adhesive tape is applied to the coating and peeled off at a defined angle (usually 90 or 180 degrees). The force required to peel it off shows how strongly the coating adheres. This method is simple and fast, but also susceptible to operator influence.2.Tensile test in the Z-direction:The adhesive tape is pulled off perpendicular to the surface , which is referred to as the Z-direction.
 This method is more reproducible, less dependent on the angle, and is particularly suitable for research and quality control. Modern devices even make it possible to test several specimens at the same time.Both methods have their merits – manufacturers often use a combination to obtain a more complete picture of the adhesion quality.