Triboelectric nanogenerators in harsh conditions: A critical review

The rapid rise in energy consumption and an accelerating climatic crisis has resulted in a surge in the study of clean energy sources. Triboelectric nanogenerators (TENGs) are energy harvesters that convert mechanical into electrical energy in a highly efficient manner. They are low cost, light, flexible, require limited maintenance and are environmentally friendly, being therefore very attractive for a large range of applications, such as wearables, self-power sensors or maritime deployment. However, harsh environmental conditions still hinder their performance. High humidity disperse the accumulated charge, while high temperatures facilitate electron emission and decrease surface charge density. Air components in the atmosphere can lead to changes in the charge tendency of tribomaterials, while pressure can hinder or enhance electrostatic breakdown conditions. Here, we thoroughly review the available literature on how TENGs outputs depend on environmental factors and how to tune material properties to preserve or even enhance TENG performance under harsh conditions. These are crucial aspects to obtain reliable and robust devices and to broaden TENG application spectrum towards commercialization.