Design And Performance Study Of Piezoelectric-assisted Enhanced Friction Nanogenerato

Smart wearable electronic devices have become an indispensable part of people’s lives.However,traditional battery supplies still have problems such as frequent replacement,heavy pollution,and poor biocompatibility.Triboelectric nanogenerators（TENG）can converted absent mechanical energy nowhere in the environment into electrical energy,which has the characteristics of simple structure,sustainable power supply,and environmentally friendly,which make up for the lack of batteries and has attracted much attention.The development of high-performance TENG is currently the main research focus in the field of micro-nano energy.In order to improve the application performance of TENG in the field of smart wearables,this paper designs a kind of piezoelectric-enhanced TENG（P-TNG）with fabric as electrode,polydimethylsiloxane（PDMS）as negative friction material,and thermoplastic polyurethane（TPU）as positive friction material.The specific research content is as follows:（1）Optimization of negative friction materials:The barium titanate/antimony tin oxide（BaTiO₃/ATO）piezoelectric composite film was prepared by the techniques of electrospinning,calcination and pouring,then embedded in PDMS to construct P-TNG.The coupling of piezoelectric effect and triboelectric effect improved output performance of P-TNG.The working mechanism of P-TNG based on the BaTiO₃/ATO composite film was discussed;in addition,the influence of the polarization and thickness of the BaTiO₃/ATO composite film on the output performance of P-TNG was studied.The results showed that:compared with pure PDMS,the embedding of BaTiO₃/ATO composite film significantly improved the output performance of P-TNG,that was,the open circuit voltage(V_oc)and short circuit current(I_sc)rised from 20 V and 4.8μA to 119 V and 28μA,respectively.Compared with the unpolarized one,V_ocand I_sc of the P-TNG based on polarized BaTiO₃/ATO composite film increased by 2.38times and 1.56 times,respectively.At the same time,under certain conditions,as the thickness of the piezoelectric layer increased,the output performance of P-TNG firstly increased and then decreased.The performance was optimal when the thickness was544μm,and its maximum output power reached 11.74μW/cm².Moreover,the electricity generated by the device could power 174 commercial light-emitting diodes（LEDs）.（2）Optimization of positive friction materials:Porous TPU film doped with multi-walled carbon nanotubes（MWCNTs@TPU film）was prepared based on the water immersion method and freeze-drying method,which utilized porous structure and strong charge storage capacity of MWCNTs,and MWCNTs helped to enhance the advantages of dielectric performance for improving the output performance of TENG.The working mechanism of MWCNTs@TPU film-based TENG and the influence of TPU concentration,TPU film thickness and doped MWCNTs concentration on the performance of TENG are explored.The results showed that compared with the dense TPU,the TENG output performance of the MWCNTs@TPU composite film has increased from 9 V,1.5μA to 40 V,12.4μA.Under certain conditions,as the concentration of TPU increased,the output performance of TENG firstly increased and then decreased.The thickness of the TPU film and the doping of MWCNTs with different contents show the same trend.When the TPU was 18 wt%,the MWCNTs concentration is 0.3 wt%,and the thickness is 1.9 mm,TENG has the best performance.This was the result of the balance between the internal pore structure,the content of MWCNTs and the flexibility of the film.When the external load was 5 MΩ,its output power reaches 0.57μW/cm².Finally,the BaTiO₃/ATO composite film-based negative friction layer and the MWCNTs@TPU film-based positive friction layer were combined to complete the final design of P-TNG,and its V_oc and I_sc reached 113.8 V and 25.6μA,respectively.The device has broad development prospects in the field of smart wearables.