Design And Construction Of High-Performance Triboelectric Nanogenerators For Energy Harvesting Applications

With the widespread application of intelligent electronics in the forthcoming Internet of Things（Io T）era,it is becoming an urgent demand to develop renewable and alternative power sources.As for such a giant and distributed net of sensors,conventional battery as the credible power source will face a range of challenges such as location tracking,periodic maintenance and environmental pollution.Fortunately,as a new nanoenergy technology,nanogenerator can cleanly and efficiently harvest various forms of renewable energy in the environment,and then achieving the self-powered and sustainable operation of electronic devices.Among them,triboelectric nanogenerator（TENG）has shown tremendous potential in energy harvesting and self-powered sensing owing to its advantages of high energy-conversion efficiency,high power output,many working modes,various selected materials,ease fabrication,and low-cost in particular.However,it is still great challenging to design and construct a high-performance triboelectric nanogenerator for practical applications as the high requirements in energy harvesting efficiency and information sensing sensitivity.Thus,it is of profound implication to explore novel strategies for significantly enhancing the triboelectric performance of TENG through materials optimization and structure design.In this dissertation,we have focused on the design and construction of high-performance triboelectric nanogenerator for energy harvesting applications.On the basis of newly developed triboelectric materials and electrode including PVA based solid polymer electrolytes,composition and surface structure dual optimized PVDF,and interface-triboelectrification enhanced carbon electrode,different enhanced TENGs for energy harvesting have been successfully fabricated.Moreover,the underlying enhancement mechanisms of these TENGs have been analyzed to provide novel strategies for high-performance TENGs design and construction in the future,which will promote the practical application of TENGs in the Io T era.The main contents and results are as follows:1.Due to fewer selection of positive triboelectric materials for TENGs,the novel PVA based solid polymer electrolytes as new triboelectric materials have been successfully developed.With the modulation effect of different electrolytes including FeCl₃,AlCl₃,ZnCl₂,CaCl₂,LiCl,high-performance PTFE-PVA/LiCl TENG were designed and constructed.Based on the optimized triboelectric property of PVA/LiCl and improved interaction with opposite tribolayer,the PTFE-PVA/LiCl TENG demonstrated significantly enhanced triboelectric performance with an output voltage of～1345 V,a short-circuit current density of～260 mA m^-2,and corresponding transferred charge density of～210μC m^-2.Specifically,the PTFE-PVA/LiCl TENG with a load resistance of 15 MΩcould achieve a maximum instantaneous power density of～83.6 W m^-2,about four times higher than that of the PTFE-PVA TENG.Hence,this work not only broadens the choice of new positive triboelectric materials but also presents new ideas of enhancing interaction between triboelectric layers to fabricate high-performance TENGs for energy harvesting.2.In consideration of limited enhancement in negative triboelectric materials with unilateral optimization,the chemical composition and surface microstructure of PVDF films have been simultaneously optimized via graphene nanosheets incorporation combined with electrospinning technology.Subsequently,in conjunction with flat PA6film,high-performance PVDF/G NF-PA6 TENGs were successfully fabricated.Owing to the enhanced triboelectric property and increased effective triboelectric area of PVDF/G NF films,the PVDF/G NF-PA6 TENGs exhibited superior triboelectric performance with an output voltage of～1511 V,a short-circuit current density of～189mA m^-2,and corresponding transferred charge density of～352μC m^-2.Especially,under impedance matching condition,the PVDF/G NF-PA6 TENG demonstrated a maximun instantaneous power density of 130.2 W m^-2,nearly eight times higher than that of PVDF/G NF-PA6 TENG.Thus,this work provides an effective strategy of simultaneously optimizing the chemical composition and surface microstructure of triboelectric materials to construct high-performance TENGs.3.Novel electrode mateirals for performance-enhanced TENG have been explored as seldom investigations have done on this previously.In combination with the flat PDMS and PA6 films,conductive carbon tapes with coarse surfaces were utilized as the electrode to fabricate significantly enhanced flat surface C|PDMS-PA6 TENGs.With the outstanding triboelectric property of PDMS film and enhanced interface triboelectrification,the C|PDMS-PA6 TENG delivered dramatically enhanced triboelectric performance with an output voltage of～1761 V,a short-circuit current density of～247.5 mA m^-2,and a corresponding transferred charge density of～326μC m^-2.In particular,when under impedance matching condition,the C|PDMS-PA6 TENG displayed a maximun instantaneous power density of～124.9 W m^-2,three times higher than that of the aluminum electrode-based Al|PDMS-PA6 TENG TENG.Furthermore,integrated with a fly-buck power management circuit,the C|PDMS-PA6 TENG achieved higher mechanical energy conversion/storage efficiency and could power commercial electronics in real-time.Therefore,this study innovatively seeks new way of boosting the triboelectric performance of TENG through electrode optimization,and proposes a promising path of enhancing interface triboelectrification between electrode and tribolayer to construct high-performance TENGs.