Why is electrode passivation necessary in TENGs?

Electrode passivation is necessary in TENGs to prevent corrosion and oxidation of the electrode material, which can significantly degrade the device's performance and lifespan. Many commonly used electrode materials, such as copper and aluminum, are susceptible to oxidation when exposed to air and moisture. The formation of an oxide layer on the electrode surface increases the contact resistance between the electrode and the triboelectric material, hindering charge collection and reducing the output current. Passivation involves coating the electrode with a thin, inert layer that protects it from environmental factors. This layer can be a dielectric material or a chemically stable metal oxide. For example, aluminum electrodes can be passivated by forming a thin layer of aluminum oxide (Al2O3) through anodization, which creates a protective barrier against further oxidation. Similarly, copper electrodes can be coated with a thin layer of gold or other noble metals. The passivation layer should be thin enough to not significantly increase the series resistance of the TENG but thick enough to provide adequate protection against corrosion. Proper passivation ensures the long-term stability and reliability of the TENG.