High triboelectrification and charge collection efficiency of direct current triboelectric nanogenerator achieved by tri-synergistic enhancement strategy

Direct current triboelectric nanogenerator (DC-TENG) utilized air-breakdown effect to collect triboelectrification charges from dielectric tribo-layers, providing a new type of mechanical energy harvesting mode for TENGs, which has demonstrated its high efficiency in energy conversion process. However, boosting the output performance based on structure designs and material modifications still meets great challenges. Herein, we propose a ternary dual-DC-TENG (TDD-TENG) with a triple synergistic enhancement mechanism. The strategies include the space optimization using multiple-unit structure on slider by seamlessly arranging PTFE/PA/electrode to realize maximized space utilization, ternary dielectric material selection by adopting PTFE, PA and PU foam as the tribo-layers with the spontaneously introduced PTFE powder on PU foam to achieve a higher triboelectrification effect and surface lubrication, and bottom electrode design to collect charges unreached by charge collection electrodes (CCEs) on slider forming a dual-DC output. Consequently, TDD-TENG achieves the average power density of 18.37 W m-2, which is the highest in sliding mode DC-TENGs. In addition, the output charge density of rotary TDD-TENG reaches 7.3 mC m-2 at an ultra-low speed of 5 rpm. This work provides a new method to improve output power from structure design and material modification for DC-TENGs.