Overcoming current leaks in CNT/PDMS triboelectric composites by wrapping CNTs with TiO2 insulation layer

The output performance of triboelectric nanogenerators (TENGs) is fatally determined by the capacitive capability of triboelectric electrodes. One promising solution is embedding conductive fillers in triboelectric polymers, typically carbon nanotubes (CNTs) in polydimethylsiloxane (PDMS). Each CNT will serve as a capacitor in the PDMS matrix to store electric energy through polarization. However, the CNTs are easily cross-linked with each other, which makes the triboelectric materials conductive or semi-conductive. The output voltage will be limited due to current leaks through conducting or tunneling, and thus, suppress the energy harvesting efficiency of TENGs. Here, we propose to use an insulation layer to wrap CNTs to avoid direct-contact between CNTs and improve the overall performance of TENGs. Our results show that the leakage current has been significantly suppressed and the output performance of TENGs has been dramatically improved. This work provides a material design idea, which is expected to become a universal method to improve the output performance of TENGs.