| With the rapid development of the technology and information era,people need more and more energy,however,the primary energy such as coal,oil,natural gas,gradually will be dried up,so it is necessary to search for new energy to meet the sustainable development of society.Solar power,wind power generation,and hydropower have been widely used.In recent years,the triboelectric nanogenerator based on the triboelectrification effect and static electric induction is widely investigated,it can collect the abandoned mechanical energy in the surrounding environment to transform it into electrical energy to power small electronic devices,realizing the miniaturization and real-time of the power supplication in order to satisfy the life.The research about nanogenerator is mainly focused on two aspects: one is the design and optimize of the electrode structure,the other is the modification of fiction materials,which is to maximum the energy and exchange efficiency.The research in this paper is to improve the performance of nanogenerator and explore the mechanism of storing charge about friction materials in terms of this two aspects,the mainly works are:(1)A novel honeycomb-like triboelectric generator(HTEG)based on three electrodes has been designed for harvesting mechanical energy in full space.It has symmetric and periodic arrangement of the three electrodes in plane or on the inner surface of ball,which can harvest sliding energy along arbitrary direction without off state because each electrode is always surrounded by the electrodes different from itself.Meanwhile,the device can effectively scavenge ambient vibration energy as an independent generator in full space by working at both contact-separation mode and sliding mode without contacting the ground.The maximum output current density,voltage and power density can reach 16.4 mA/m2,413 V,and 2.1 W/m2,respectively by working in plane sliding mode,and the maximum output current is 0.55 μA by working in sliding mode on an inner surface of a spherical shell.The HTEG can charge a 100 μF commercial capacitor to 2.1 V in 80 s.The football-like HTEG is used as a vibration alertor,which could be applied in vibration monitor or geologic hazard alertor for bridges and buildings.The idea of multi-electrode in HTEGs would be an effective strategy to achieve multi-function in scavenging energy.(2)An easily foldable and portable triboelectric-electromagnetic generator(TEMG)based on two polymer/Al layers and one copper coil has been designed to harvest ambient mechanical energy,where the copper coil is used both as a spring to achieve contact and separation of triboelectric layers and as a vital part of the circuit to collect electromagnetic-induced electricity.The output performance of the TEMG is approximately reproducible after being folded many times.The working mechanism is discussed.The output performance of individual triboelectric generator(TEG)and electromagnetic generator(EMG)are systematically investigated.The maximum output current,voltage,and power are obtained to be 32.2 μA,500 V,and 2 mW for the TEG,and 4.04 mA,30 mV,and 15.8 μW for the EMG,respectively.The TEG with a higher internal resistance can be used as a current source,while the EMG with a lower resistance can be used as a voltage source.It can be used as a mobile light source via integrating the TEMG in clothes or bags,and as a self-powered gas flow sensor for detecting respiratory rate,which has a potential application in medical diagnoses.The simple structure and easy portability of the TEMG could be used widely in daily life to harvest ambient energy for electronic devices.(3)Polydimethylsiloxane(PDMS)is an excellent material for investigating the mechanism of triboelectricity as it can easily be used to construct various microstructures.In this study,micro-capacitors(MCs)and variable microcapacitors(VMCs)were embedded in PDMS by filling PDMS with silver nanoparticles(NPs)and constructing an internal cellular structure.The output performance of the triboelectric nanogenerators(TENGs)based on MCs@PDMS and VMCs@PDMS films was systematically investigated,with variation of the filling content of silver NPs and the pore ratio and size.The microstructure,permittivity,dielectric loss,and capacitance of the VMCs@PDMS films were well characterized.The output current of the TENG based on the VMCs@PDMS film was respectively 4.0 and 1.6 times higher than that of the TENGs based on the pure PDMS film and MCs@PDMS film,and the output power density of the former reached 6 W·m–2.This study sheds light on the physical nature of conductive nanoparticle fillings and cellular structures in dielectric triboelectric polymers.(4)Aligned graphene sheets(AGS)embedded in PDMS(AGS@PDMS)has been prepared by repeated spin-coating(SC)technique.The triboelectric nanogenerator(TENG)based on the AGS@PDMS film is fabricated and its electric output is investigated systematically with different contents of filling graphene sheets and different spin-coating layers.The PDMS embedded with AGS is compared with that of disordered graphene sheets and graphite particles with different sizes.The capacitance,dielectric loss,conductivity and resistance of the PDMS composite film are characterized and analyzed.The output current of the TENG based on AGS@PDMS film is 3 times as much as that of the TENG based on pure PDMS film and the output power density reaches 4.8 W/m2 at the load resistance of 15 MΩ.In addition,the TENG can be used as a pressure sensor to measure the mass and height of an object.This work demonstrates that the voltage applied on whole TENG is distributed to micro capacitors formed by aligned graphene sheets in PDMS,by which the higher breakdown voltage and energy conversion ability are achieved. |
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