Performance Enhanced Triboelectric Nanogenerator By Taking Advantage Of Water In Humid Environments

With the rapid development and wide application of the Internet of things,intelligent wearable electronic devices and biomedical implantable electronic devices,the traditional energy supply methods(such as batteries and wired power supply)are facing unprecedented challenges due to limited capacity,complicated wiring layout and environmental pollution.As an efficient energy collection technology,triboelectric nanogenerator(TENG)can convert the weak mechanical energy in the environment into electrical energy.It has the advantages of low cost,light weight,high energy conversion efficiency,high output power,high matching,good reliability and environmental compatibility.It has great potential in the field of portable energy and intelligent wearable.With more and more applications,TENG needs to adapt to more application scenarios.However,under high humidity,water molecules in the atmosphere are easy to adsorb on the surface of friction layer to form water film,which accelerates the dissipation of friction charge on the surface of friction layer,which leads to the serious reduction of the output performance and stability of TENG.Therefore,improving the performance of TENG in high humidity environment is very important for its application in blue energy,humidity monitoring,implantable nano devices and so on.In this paper,a kind of humidity-resisting triboelectric nanogenerator(HR-TENG)based on polyvinyl alcohol(PVA)was developed.A large number of hydroxyl groups in PVA can fix water molecules through hydrogen bonding,so that more water molecules with positive friction electrode can participate in the friction process and improve the ability of gain and loss of electrons of the friction layer as a whole.ifferent from using packaging and superhydrophobic materials to reduce the influence of humidity on the output of TENG,HR-TENG can use ambient humidity to enhance its output performance.In addition,by doping LiCl into PVA to adjust the water absorption capacity of PVA/LiCl friction layer,a large number of micro fold structures are introduced on the surface of PVA/LiCl friction layer,and the modulus of the film is reduced to achieve more effective contact efficiency.By adjusting the proportion of LiCl doping,HR-TENG can achieve ultra-high output performance under various high relative humidity(RH)conditions,In a wide range of relative humidity(from 60%to 99%),the charge density is always higher than 110?C/m~2(the maximum charge density of humidity-resisting TENG at high humidity).Under the optimized driving conditions and the use of ICP treated PTFE,the output voltage and current were increased to 664 V and 37?A respectively at RH90%,and the charge density reached244?C/m~2,which was 2.21 times of the highest reported value.Based on the excellent output performance of HR-TENG in high humidity,as well as good stability and durability,a self powered humidity early warning system is developed,which can monitor the ambient humidity in real time.When the relative humidity is too high,the indicator light can flash to remind the staff to take corresponding measures in time;In addition,HR-TENG also has ultra sensitive humidity response performance,which can be developed as a human respiratory monitoring device.By observing the waveform,size and frequency of voltage output signal,HR-TENG can monitor human respiratory status(fast breathing,slow breathing and deep breathing)in real time.This work will strongly promote the development of friction nano generator,and has great application prospects in the realization of self powered system under high humidity and human physiological monitoring.