Structure And Piezoelectric Property Of ZnO/PVDF Composite Films Made In Electrostatic Field

With the advancement in the field of technology in the recent years,wearable smart devices and portable electronic systems are growing rapidly.The size of the devices has been reduced to make it portable,efficient,and easy to handle at the cost of decreasing the size of the batteries,which brought challenges to the power system.Now days,a large number of devices depend on batteries.But batteries have many disadvantages including bigger volume,heavyer weight and lower power density,which cannot satisfy peoples request about portable devices.Therefore,research on self-sufficient power system has becoming a milestone in power technology industry.Piezoelectric devices that can translate mechanical energy into electricity to drive smart electronics would be one of the most promising technology to solve the power problems of portable smart electronics.Polyvinylidene fluoride are lightweight and piezoelectric after polarization,which make them suited for wearable devices.In order to enhance the output power of Zn O/PVDF composite film,we producted a series of ZnO/PVDF composite film which are made in 20 kV electrostatic field,with high output power and stability based on investigating the influencing factors of ZnO/PVDF composite films.Those thesises are conducted from the following aspects:1.ZnO/PVDF composite films are prepared directly without any post-poling treatment in electrostatic field.The effect of the addition of ZnO on the surface morphology of PVDF composite films,β-phase composition,output piezoelectric voltage of Zn O/PVDF composite films are investigated.With the increasing concentration of ZnO,the average diameter of holes in ZnO/PVDF composite films surface increased firstly and then decreased when the ZnO is too much.Moderate Zn O is helpful to β-phase formation which are verified by XRD and FTIR.The maximum generated piezo-voltage exhibited by ZnO/PVDF composite films in the presence of 3wt% is highest which is 27.84 V.2.PVDF-ZnO 3wt% composite films in different thickness are prepared directly without any post-poling treatment in electrostatic field.The effect of the thickness of ZnO/ PVDF composite films on the surface morphology of PVDF composite films,β-phase composition,output piezoelectric voltage of ZnO/PVDF composite films are investigated.With the increasing thickness of composite films,the average diameter of holes in ZnO/PVDF composite films surface decreased and the density of holes are increased.Increasing thickness of composite films almost makes no contribution to β-phase formation which are verified by XRD and FTIR.The thicker the composite films,the output voltage is lower in same shock.The highest output voltage of composite films is 35.52 V,when the thickness of composite film is 1.0 mm.When the thickness of composite film is 2.5 mm,the much the shock,the higher the output voltage of composite film.3.PVDF-ZnO 3wt% composite films with 1.0 mm thick made in different solvent systems which made up of acetone and DMF are prepared directly without any post-poling treatment in electrostatic field.The effect of volume fraction of acetone on the surface morphology of PVDF composite films,β-phase composition,output piezoelectric voltage of Zn O/PVDF composite films are investigated.With the volume fraction of acetone increased,the average diameter of holes in ZnO/PVDF composite films surface decreased.When the volume fraction of acetone arrived 70%,the holes on surface of composite films almost disappeared.Increasing the volume fraction of acetone almost makes no contribution to β-phase formation which are verified by XRD and FTIR.The highest crystalline degree of β-phase is 5.6% bigger than the lowest crystalline degree of β-phase.Composite films made in composite solution(acetone 30%)can product highest output voltage which arrived 18.76 V.It is also found that the instantaneous output power is found to be maximum for Composite films made in composite solution(acetone 30%)at the load resistance.By connecting two composite films in serial,the peak voltage output has increased,which was approximately the sum of the peak voltage of each composite film.Meanwhile,the peak current almost did not change.For parallel connection,the peak current was twice than each composite film.Meanwhile the peak voltage remained at nearly the same individual level.This result revealed that PVDF composite films integration followed the general rules of battery connection.