Boosting the maximized output energy density of triboelectric nanogenerator

Abstract

Volumetric energy density is a universal and the most important standardized figure-of-merit to quantify energy technologies, regardless of the operating mechanism, form of energy, energy scale, etc. In terms of triboelectric nanogenerator (TENG), considering its cycle-by-cycle operation mechanism, output energy density has been demonstrated as the key limiting factor on its output performance. However, it is limited by two crucial factors: charge density and breakdown threshold voltage. In this work, we proposed a comprehensive strategy including charge excitation, interface insulation, and material screening to boost the maximized output energy density of the TENG. In particular, charge excitation was effectively realized by an external high-voltage (HV) source, while interface insulation was proved through introducing liquid oils to alleviate electric field and suppress the breakdown effect. Moreover, a set of comprehensive parameters involving triboelectrification, dielectric properties, leakage properties, etc. are fully investigated for screening triboelectric materials. With that, we experimentally achieved a record-high charge density of 2.3 mC/m2 among SFT-TENG and yielded the maximum output energy density of 4.3×105 J/m3, as a new record in the field. A theoretical maximum energy density of 1.1×106 J/m3 is predicted as simulated by finite-element method. This work demonstrates the boosted capability of TENG's maximized output energy density from both theoretical and experimental perspectives, which not only be an important step towards designing high-performance TENG for energy harvesting but also will promote its wide application across energy devices.