Study On The Application And High Performance Of Triboelectric Nanogenerators Based On PEO Material

Recently,electronic devices and systems have developed rapidly in the direction of portability,miniaturization and multifunction.How to power these huge quantities of microelectronic devices has become an urgent problem in the development of information technology and the electronics industiy.Triboclectric nanogenerators have been extensively studied since being proposed by Wang Zhonglin in 2012.TENGs have successfully collected and utilized the electricity generated by the triboelectric effect that has puzzled people for thousands of years,realizing a new sustainable and green energy source.Triboelectric nanogenerators(TENGs)are based on the coupling of the triboelectric effect and the electrostatic induction,which can effectively convert the mechanical energy into electrical energy.The difference in electron affinity between the materials is a key factor affecting the perfonnance of the TENGs.In recent years,Vigorous investigations have significantly improved the performance of TENGs.On the contrary,not much attention has been paid to the selection of positive tribo-materials,even though they are equally important as the negative tribo-materials for enhancing the output performance of TENGs.In this paper,a high-performance TENG is proposed by using polyethylene oxide(PEO)as the positive tribo-material,and the mechanism and corresponding application are also explored.The main work and achievements of the thesis are as follows:1.PEO films with different molecular weights were prepared by spin coating method,which were 100,000,600,000 and 300,000 g/mol respectively.At the same time,PA6 membranes were prepared for comparison.They were combined with PDMS films to prepare vertical contact-separation mode TENGs.A dynamic fatigue tester system was utilized to characterize the TENGs by controlling the periodic separation and contact of two tribo-plates.A 2 × 2 cm2 PEO/PDMS TENG produces an open circuit voltage of up to 970 V,a current density of 85 mA/m2,and a maximum instantaneous power of～40 W/m2 under a 50 N contact force.Comparatively,the PA6/PDMS TENG only produces 630 V,30 mA/m2,and a power of～18 W/m2 under the same condition.The experimental results show that the PEO films have a higher positive electron affinity as compared to PA6,and the molecular weight of PEO has a limited effect on triboelectric properties of TENG.Furthermore,when PDMS is replaced with other common negative tribo-materials such as PET,FEP,etc.PEO films show higher output performance,demonstrating the generalty of PEO as a positive tribo-material.2.The electrical output of the PEO/PDMS TENG under varying impact forces,impact frequencies and spacer distances were studied.The results show that all three factors have a significant impact on the performance of TENG.With the impact frequencies,spacer distances and impact forces gradually increase,and the output voltage and current density generally increase first and then stabilize.3.To investigate the mechanism for high performance TENG with PEO film,we characterized the surface potential of PA6 and PEO films with different molecular weights using KPFM.For the PA6 film,the measured contact potential difference value is 0.875 V,much lower than that obtained by the PEO film which displayed value of 1.26V.And the molecular weight of PEO film has only a limited effect on the surface potential.Meanwhile,the functional groups of PEO were characterized by FTIR,and the results show that PEO has abundant functional groups such as OH bonds.These results well explain the reason for PEO has higher positive tirbo-polarity.4.Aiming at the AC output characteristics of TENGs and the low efficiency in direct charging storage because of high internal resistance,this paper adopts a fly-buck circuit,which greatly improves the charging speed and energy conversion efficiency of TENGs.As the TENGs were operated under the same conditions,the voltage on the 100 μF capacitor rises from 0 V to 2 V in 5 s using the fly-buck charging circuit,the standard circuit can only charge up to 0.04 V,corresponding to a charging speed of 0.4 V/s and 0.008 V/s,respectively,increasing 50 times! And due to the fast charging abilities of the fly-buck circuit,the TENGs can be used to drive electronic devices in real time,such as a commercial calculator.