High Output Direct-Current Nanogenerators Based on Charge Redistribution at Wet Cellulose/Metal Contact Interfaces

Abstract

In the present work, a wet cellulose sponge-based direct-current electric generator (WCS-DCEG) is proposed, which offers a new power generation methodology for harvesting mechanical energy through an extremely simple structure. The device consists of two electrodes located on the surface of a dielectric substrate to collect direct-current output from the sliding motion of a wet cellulose sponge. Here, mechanical energy is converted into electrostatic energy by the triboelectric effect, and then, electrical energy is obtained due to the charging effect between two electrodes with different work functions. This is different from the traditional triboelectric nanogenerators which generate electricity through the electrostatic induction process. A single WCS-DCEG is capable to produce a current density of 75 μA/cm2 and an induced voltage of approximately 0.48–0.90 V with direct-current characteristics. The voltage and current outputs can be increased by synchronizing the outputs of multiple units of WCS-DCEG connecting in series or parallel. Additionally, WCS-DCEG proves a great accuracy for measuring the ion concentration in an aqueous solution ( R 2 = 0.996 ). These findings exhibit the great potential application of WCS-DCEG as an efficient strategy for harvesting mechanical energy and in the field of self-powered sensor fabrication.