Studies On Property Modulation And Power Generation Characteristics In Lead-free Piezoelectric Ceramic For Energy Harvesting

In recent years,the internet of things and wearable electronics have flourished,which has made piezoelectric energy harvesting a research hotspot in the new energy field.Among them,the key chalenge is to design environmentally-friendly piezoelectric materials with high energy density.In this study,we focus on the performance requirements of piezoelectric ceramics for energy harvesting devices and select high-performance barium titanium-based lead-free piezoelectric materials as the research object.The energy harvesting performance of the barium titanate-based piezoelectric ceramic material was improved by phase-boundary tuning and doping modification,respectively.The power-generation characteristics of ceramics was evaluated using a cantilever beam type energy harvester,and the correlation among microstructure,piezoelectricity,and power generation performance of the ceramics was investigated.Thus,a vibration energy harvester with high power density and energy conversion efficiency is obtained.Firstly,to build a energy harvester with high power density,a novel lead-free material system of?1-x?Ba(Zr_0.1985Cu_0.0015Ti_0.8)O_3-?–x(Ba_0.7Ca_0.3)TiO₃[BCTZC]was designed,and the energy harvesting characteristics were tailored through the composition-driven phase boundary evolution.The results indicate that when x=0.55,the BCTZC ceramic is lie in the rhombohedral-orthorhombic-tetragonal?R-O-T?polycrystalline phase boundary.Therefore,the ceramic has large piezoelectric activity and its energy harvesting performance:g₃₃=14.7×10^-3 Vm/N,d₃₃×g₃₃=4257×10^-15m²/N,?=0.95,DFOM=995.Further,we evaluated their power generation performance through energy harvesters equipped with cantilever structure.It was found that the resonance frequency of the cantilever-type energy harvester is 90 Hz.At resonance frequency,a high output power of 70?W and voltage of 8 V were obtained at x=0.55 specimen under an acceleration of 10 m/s²,which were further increased to700?W and 25 V when the acceleration increased to 50 m/s².The excelent low frequency power-generation characteristics show the potential applications of BCTZC material in piezoelectric generators harvesting environmental vibration energy.Secondly,in order to further study the energy conversion efficiency and work stability of the energy harvester,lead-free Ba_0.9Ca_0.1Ti_0.93Zr_0.07O₃?BCTZ?ceramics were prepared,and power characteristics of BCTZ(Ba_0.9Ca_0.1Ti_0.93Zr_0.07O₃+x mol.%MnO₂,abbreviated as BCTZ+x Mn)ceramics were improved by addition of Mn ions.The results showed that when x=0.55,the BCTZ ceramic is lie in R-O-T polycrystalline phase boundary,and possesses a uniform dense microstructure,boosting the high energy harvesting performance at x=0.1 specimen.The energy conversion efficiency of x=0.1 energy harvester was studied by a cantilever beam structure.The results show that a high power density of 1.2?W/mm³ and efficiency of energy conversion of 7%were obtained at x=0.1 specimen under an acceleration of 10 m/s².In addition,the BCTZ energy harvester possesses outstanding and stable power generation performance after a 10⁶ cycles,as well as strong adaptability against different acceleration vibration environments.This work further promoted the development of high-efficiency lead-free energy harvesters and laid a solid foundation for the application of lead-free piezoelectric energy harvesters.