Magnetic capsulate triboelectric nanogenerators

Abstract

Triboelectric nanogenerators have received significant research attention in recent years. Structural design plays a critical role in improving the energy harvesting performance of triboelectric nanogenerators. Here, we develop the magnetic capsulate triboelectric nanogenerators (MC-TENG) for energy harvesting under undesirable mechanical excitations. The capsulate TENG are designed to be driven by an oscillation-triggered magnetic force in a holding frame to generate electrical power due to the principle of the freestanding triboelectrification. Experimental and numerical studies are conducted to investigate the electrical performance of MC-TENG under cyclic loading in three energy harvesting modes. The results indicate that the energy harvesting performance of the MC-TENG is significantly affected by the structure of the capsulate TENG. The copper MC-TENG systems are found to be the most effective design that generates the maximum mode of the voltage range is 4 V in the closed-circuit with the resistance of 10 GΩ. The proposed MC-TENG concept provides an effective method to harvest electrical energy from low-frequency and low-amplitude oscillations such as ocean wave.

Figure 1

Design principle of the MC-TENG. (a) Principal illustration of the freestanding triboelectric layer mode used in the MC-TENG. (b) series of triboelectric material. (c) Application of the MC-TENG in ocean wave, the three oscillation scenarios of the capsulate TENG (i.e., the dielectric) in the holding frame (i.e., the electrode) between the driven magnets, and the process comparison with the experimental observations recorded by a high-speed camera (conceptual images are created by SolidWorks 2017 SP4.1 https://www.solidworks.com/). (d) The components of the copper MC-TENG including the copper legs, holding frame, central connector, steel strips, and driven magnets. (e) Design details and assembly of the copper MC-TENG with four magnetic capsulate systems.

Figure 2

Fabrication of the capsulate TENG and experimental setup of the MC-TENG. (a) Experimental setup of the MC-TENG fabricated with the materials of copper and aluminum in the single-layered (mode 1), double-layered (mode 2) and non-layered (mode 3) structures. Design and fabrication of the capsulate TENG using (b) copper and (c) aluminum in mode 1 and mode 2 with different end magnets. (d) Design and fabrication of the copper/aluminum capsulate TENG in mode 3 with different end magnets (all the capsules were fabricated with 1 to 4 end magnets on 1 or 2 layers) (Conceptual images are created by SolidWorks 2017 SP4.1 https://www.solidworks.com/).

Figure 3

Energy harvesting performance of the copper and aluminum MC-TENG in the three modes. Voltage distribution trends of the (a) copper and (b) aluminum MC-TENG in mode 1, (c) copper and (d) aluminum MC-TENG in mode 2, and (e) copper and (f) aluminum MC-TENG in mode 3 (all the capsulate TENG are designed with 4 end magnets on each end, the loading time is fixed as 2 s, and the electrical resistance in the closed-circuit is varied from 1 MΩ to 10 GΩ).

Figure 4

Influences of the end magnets, material and structure on the energy harvesting performance of the MC-TENG. (a) Voltage distribution with respect to the end magnets for the copper or aluminum MC-TENG in the open-circuit. (b) Voltage (c) power and (d) current distributions of the MC-TENG in terms of the electrical resistance in the closed-circuit with 4 end magnets on each end (Sgl 4) (all the capsulate TENG are designed in mode 1, mode 2 and mode 3). (e) Stability test of MC-TENG under 5000 cyclic loading during 1800s.

Figure 5

Numerical modeling of the copper MC-TENG and comparing with the experiments. (a) Numerical setup, mesh and electrical potential contour of the copper capsule in mode 2. Output voltages of the copper MC-TENG in (b) mode 1, (c) mode 2, and (d) mode 3. (e) Comparison of the voltage between the experimental results (${\mathrm{V}}_{\mathrm{Exp}}$) and numerical results (${\mathrm{V}}_{\mathrm{FE}}$) for the copper MC-TENG (all the capsules are designed with 1 end magnet on each end, and the voltages are obtained in the closed-circuit with the electrical resistance of 10 GΩ).