Professor Zheng Haiwu, Henan University / Academician Wang Zhonglin, Beijing Institute of nano energy and systems, Chinese Academy of Sciences: doping and three-dimensional structure design to improve the output of high-voltage electric nano generator

In recent years, the sensor network and the Internet of things, which are composed of portable electronic devices, have made rapid development However, due to the huge number and environmental and health reasons, if each sensor is powered by a battery, this kind of sensor network will be difficult to achieve Therefore, as a new technology of mechanical energy conversion to electrical energy, piezoelectric nano generator will play an important role in the development of the Internet of things Recently, Professor Zheng Haiwu of Henan University and Academician Wang Zhonglin of Beijing Institute of nano energy and system of Chinese Academy of sciences have made new progress in this field (adv funct Mater., DOI: 10.1002 / ADFM 201904259) (from left to right: Zhang Yaju, Li Hui, Academician Wang Zhonglin, Professor Zheng Haiwu, Zhang Yuanzheng, Zhu Quanyong, Wu Yonghui) introduction to Academician Wang Zhonglin, director and chief scientist of Beijing Institute of nano energy and systems, Chinese Academy of Sciences, Professor of the board of directors of the University of Georgia for life, Professor of the high tower for life Professor Wang is the winner of the Albert Einstein World Award of Science in 2019, Eni award the "Nobel Prize" for energy in 2018, Thomson Reuters citation laureate award in 2015, J Ames C McGrady new material award in 2014 and Mrs medal in 2011 He is a foreign academician of the Chinese Academy of Sciences, the European Academy of Sciences and the Canadian Academy of engineering He is the founding editor and current editor of nano energy (latest if: 15.548), a famous international journal in the field of nano energy Prof Zheng Haiwu, Ph.D., Professor of Henan University, distinguished professor of Henan University, doctoral supervisor, member of local committee of dielectric Professional Committee of Chinese physical society, academic and technical leader of Henan Provincial Department of education, and leader of scientific and technological innovation team of colleges and universities in Henan Province From May 2015 to June 2016, I worked as a national public visiting scholar at Georgia Institute of technology, and from March 2017 to September 2017, I worked as a short-term visiting scholar at the Twin City Campus of the University of Minnesota In recent years, he has published more than 70 papers in SCI journals such as nano energy, adv funct Mater., J mater Chem A / C, ACS appl Mater Interfaces, appl Phys Lett The main research direction is the composite energy capture and polarization device physics based on Nanogenerator Mr Wu Yonghui, master's degree, lecturer of Henan University, member of the professional committee of Henan electrical and electronic laboratory construction, mainly engaged in electronic circuit design and application research, basic circuit and electronic theory and experiment teaching In recent years, he has published 6 papers in SCI journals such as nano energy, adv funct Mater., ACS appl Mater Interfaces, nanoscale and so on Mainly responsible for circuit design in the research group Cutting edge research achievements: doping and three-dimensional structure design improve the output of high-voltage electric nano generator Because the flexible piezoelectric nano generator has the ability to convert low-frequency mechanical energy into electrical energy in the surrounding environment, it will play a huge role in the development of the Internet of things Generally speaking, the electrical output of piezoelectric nano generator based on organic-inorganic composite membrane depends on the piezoelectric properties of piezoelectric filler and the stress transfer ability of composite membrane, especially the latter However, when the flexible piezoelectric nano generator is stimulated by external mechanical stimulation, most of the stress will be absorbed by the flexible matrix, so the output of the piezoelectric nano generator is not high The researchers envision whether the output performance of the piezoelectric nano generator can be improved by improving the piezoelectric properties of the piezoelectric filler and increasing the stress transfer capacity of the piezoelectric nano generator The researchers found that the rare earth elements Ti and SM doped bismuth ferrite can transform the rhombic phase of bismuth ferrite into the quasi homomorphic phase boundary (MPB) in which rhombic phase and orthorhombic phase coexist, which can significantly improve the piezoelectric properties As a breakthrough, the researchers used freeze-drying technology to prepare porous interconnected piezoelectric ceramics, in order to enhance the stress transfer ability of piezoelectric nano generator In this method, silica gel is used as the flexible matrix, cellulose as the skeleton, and titanium samarium Co doped bismuth ferrite (bsfto) as the piezoelectric filler The experimental materials are simple and easy to obtain The process of preparing the flexible piezoelectric nano generator based on the porous interconnection piezoelectric filler is shown in Figure 1 Figure 1: preparation of flexible piezoelectric Nanogenerator based on porous interconnecting piezoelectric filler (source: adv funct Mater.) Figure 2 (a) shows SEM images of bsfto uniformly distributed on fibers after freeze-drying of bsfto and cellulose Fig 2 (b) shows the SEM image of bsfto particles interconnected to form a porous three-dimensional interconnected piezoelectric filler after the freeze-dried sample was sintered at high temperature to remove cellulose In the process of compounding with the flexible matrix, the piezoelectric filler can not only be fully mixed with the flexible matrix, but also be connected with each other When the piezoelectric nano generator is excited by the external force, the stress can be transferred directly through the piezoelectric filler, so it has a higher stress transfer ability Figure 2: SEM images of samples (a) after freeze-drying and (b) after high-temperature sintering (source: adv funct Mater.) then the researchers tested the electrical performance of piezoelectric nanogenerators with different piezoelectric filler composite amount, and found that when the mass fraction of piezoelectric filler was 30% The open circuit voltage, the short circuit current density and the instantaneous maximum power density are 16 V, 0.62 μ a · cm - 2 and 3.11 μ w · cm - 2, respectively, which can be compared with the output performance of other piezoelectric nano generators This shows that freeze-drying technology is an effective way to improve the output performance of piezoelectric nano generator On this basis, the researchers have also tested the performance of the four piezoelectric nano generators: undoped freeze-drying (BPG), undoped freeze-drying (bspg), undoped freeze-drying (3bpg) and doped freeze-drying (3bsspg), and found that the performance output of 3bspg is the best See Figure 3 for the performance parameters of four piezoelectric nano generators Figure 3: output performance of four different types of piezoelectric nanogenerators (source: adv funct Mater.) during the experimental exploration, the researchers also found that the gain of doping on performance and the gain of freeze-drying on performance are independent of each other See Table 1 for specific gain effect When the two methods are used together, the gain effect is equal to the product of their respective gains Table 1: gain effects of doping and freeze-drying on performance output (source: adv funct Mater.) the researchers realized that if theoretical calculation can be used to verify the experimental results, the work will be more systematic and logical Therefore, the researchers use the multi physical field simulation software COMSOL to simulate the random distribution of piezoelectric packing and the three-dimensional porous interconnection distribution in this work Through the calculation, the model with three-dimensional porous interconnection distribution of piezoelectric filler has greater stress transfer capacity, so the composite membrane surface also has greater piezoelectric potential The detailed calculation results are shown in Figure 4 Figure 4: stress transfer ability and piezoelectric potential (source: adv funct Mater.) of different types of piezoelectric nanogenerators are analyzed by COMSOL Finally, researchers successfully use piezoelectric voltage signal as trigger signal by designing amplification circuit and comparison circuit, and realize self driving mechanical sensing system It can control the household appliances in the external circuit wirelessly When the system is applied to the fire extinguisher, the firefighter can put out the fire without entering the flammable and explosive scene The illustration is shown in Figure 5 Figure 5: schematic diagram of self driving mechanical sensor system (source: adv funct Mater.) Summary: researchers effectively improve the output of piezoelectric nano generator by doping piezoelectric materials and reasonable three-dimensional structure design It is verified by COMSOL simulation software Finally, the self driving mechanical sensor system is realized by the circuit This work was published in adv function Mater (DOI: 10.1002 / ADFM 201904259) under the title of "performance enhancement of flexible piezoelectric Nanogenerator via doping and rational 3D structure design for self powered mechanical system" The first author is Zhang Yuanzheng, a master student of Henan University, The corresponding authors are Zheng Haiwu, Professor of Henan University, Wu Yonghui, lecturer, and Wang Zhonglin, academician of Beijing Institute of nano energy and system, Chinese Academy of Sciences This work has been supported by the Ministry of science and technology, the National Natural Science Foundation of China and the science and technology innovation team support program of colleges and universities in Henan Province Nowadays, people and scientific research have been paid more and more attention in the economic life China has ushered in the "node of science and technology explosion" Behind the progress of science and technology is the work of countless scientists In the field of chemistry, in the context of the pursuit of innovation driven, international cooperation has been strengthened, the influence of Returned Scholars in the field of R & D has become increasingly prominent, and many excellent research groups have emerged in China For this reason, CBG information adopts the 1 + X reporting mechanism CBG information, chembeangoapp, chembeango official microblog, CBG wechat subscription number and other platforms jointly launch the column of "people and scientific research", approach the domestic representative research group, pay attention to their research, listen to their stories, record their demeanor, and explore their scientific research spirit.