Constructing highly flexible dielectric sponge for enhancing triboelectric performance

Functional materials that are with high dielectric constant are finding extensive applications in the conversion and storage of energy, which may also be the key for enhancing the output performance of triboelectric nanogenerator (TENG) by dielectrically modulating the charge trapping capability of the triboelectric interface. Here, CaCu3Ti4O12@BaTiO3 (CCTO@BT) is facilely synthesized for forming in polydimethylsiloxane (PDMS) layer. Due to the strengthened charge induction, the composite sponge with high flexibility and charge trapping capability is developed, and the polymeric sponge TENG (with 2 wt% CCTO@BaTiO3) demonstrates a high open-circuit voltage of 291.14 V, a short-circuit current of 35.49 µA, and a transfer charge quantity of 80 nC, which are far superior 206% higher than that are modulated by pure CCTO and 480% higher than pure PDMS (the short-circuit current). Dielectric enhancement mechanism was comparatively proved and demonstrated in the CCTO@BT/PDMS composites. To unravel the origin of the significantly enhanced triboelectric performance, permittivity and work function in the sponge were studied in-depth, and the strong internal polarization and potential barrier height were demonstrated. Moreover, the as-fabricated TENG can act as self-powered sensor for monitoring human motions, such as walking, jogging, and jumping ropes. This work provides a new insight into the unique potential of dielectric-modulated output enhancement strategy for unblocking the potential of TENG in energy harvesting and biophysical monitoring.