Research On Novel Nanogenerators And Their Applications

With the development of Internet of Things（Io T）,breakthroughs have been made in wearable devices,wireless Sensor Networks,and human-computer interaction,promoting the development of electronics to miniaturization,intelligence,and mobility.Sensors,as the most basic component of Io T,have the characteristics of high quantity and low power consumption.Their power is generally in the m W or W scale.If the Io T continues to develop,the number of sensors will be massive.How to power these electronics in the Io T becomes an urgent problem to be solved.In such a complex application environment as Io T,the shortcomings of traditional energy technologies represented by the battery gradually emerge:limited energy storage density,regular maintenance,and environmental pollution for example.People need a new alternative energy source urgently.Nanogenerators,as a new energy technology,can convert disordered energy in the environment into electrical energy,and become a promising alternative solution to this dilemma.Therefore,it is of profound implication to explore strategies for realizing high-performance nanogenerators and novel application of the energy from nanogenerators.Firstly,a composite film based on two-dimensional boron nitride nanosheets（BNNS）is developed to enhance the performance of triboelectric nanogenerators.Then by using this film,a piezoelectric/triboelectric nanogenerator（PTEG）is proposed.Secondly,in order to solve the problem of low and unstable surface charge density of solid-liquid nanogenerators,we apply the ferroelectric lead zirconate titanate（PZT）film to solid-liquid nanogenerators,which significantly improves their surface charge density and stability.Then,two kinds of solid-liquid nanogenerators based on PZT films are proposed.Lastly,in order to extend the application of nanogenerators,a wireless triboelectric nanogenerator system based on electric field resonance（EFR-WTENG）is proposed in this paper.The main research contents and results are summarized as follows:1.The BNNS-PDMS composite film with piezoelectric effect was prepared by doping BNNS into polymer,which has a piezoelectric constant d₃₃ of～12 p C N^-1.Next,a PTEG with piezoelectric and triboelectric effects was prepared by using the BNNS-PDMS composite film.The peak output voltage reaches 1870 V and the peak short-circuit current density reaches 230 m A m^-2.The max peak power density of the BNNS-PDMS/PA6 PTEG is 103.7 W m^-2 at the optimum load of 200 MΩ,which is more than three times higher than that of the control group without BNNS.Considering the advantages of BNNS such as low cost,high thermal conductivity and high stability,PTEG has a promising future in the field of self-powered sensing and energy harvesting.2.Based on ferroelectric PZT film,two solid-liquid nanogenerators are proposed:one is the direct current（DC）droplet electric nanogenerator（PZT-DEG）for collecting the kinetic energy of falling droplets,and the other is the droplet vibration nanogenerator（PZT-VDEG）for collecting the external vibration energy by using the deformation of droplets.The effective charge densities of these two solid-liquid nanogenerators are 5.4 m C m^-2（PZT-DEG）and 8.9 m C m^-2（PZT-VDEG）,respectively.By utilizing the separation effect on droplet charges by PZT,the PZT-DEG achieves a DC pulse output that can power electronics without rectifier.After optimization,the PZT-DEG achieves a peak short-circuit current of 1347μA,a net charge transfer of0.65μC in a single cycle,and a peak output voltage of 1.1 V.The max peak power density is 5.3 W m^-2 at the optimum load of 1 kΩ.The PZT-VDEG also has good output characteristics,with a peak short-circuit current of 104.3μA,a maximum charge transfer of 0.95μC,and a peak output voltage of 1.4 V.The max peak power density reaches 43.5 m W m^-2 at the optimal load of 50 kΩ.This study provides a new strategy to break the bottleneck of solid-liquid nanogenerators,which has great potential in the application of harvesting raindrop kinetic energy and tidal energy.3.We innovatively combine the high-voltage output pulse of TENG with capacitive power transfer to propose a wireless triboelectric nanogenerator system based on electric field resonance（EFR-WTENG）.The pulse generated by TENG was modulated into a high-frequency oscillation signal at the transmitter side.Then the oscillation signal was transmitted wirelessly to the receiver side via electric field resonance coupling.After optimization,an energy transfer efficiency of～67.8%was achieved at a distance of 5 cm.Theoretical models of the capacitive coupler and EFR-WTENG system were developed.The simulation results are in good agreement with the experimental results.Finally,a flexible wireless energy supply application and a self-powered wireless sensing application based on EFR-WTENG were developed.This study provides a new strategy to utilize the energy of nanogenerators.