The Construction And Mechanism Of Liquidliquid Tribosletric Nanogenerator

Since triboelectric nanogenerator(TENG)was proposed by Wang et al.in2012,it has gradually become a hot research field because of its cost-efficient energy collection capacity.The working principle of TENG is based on the coupling effect of contact electrification and electrostatic induction.The displacement current of Maxwell equation caused by relative displacement of different contact surfaces due to the action of external mechanical force is the main reason for the output of external current.Based on the coupling effect of contact electrification(CE)and electrostatic induction,TENG is a novel technology used to collect micro/nano energies in the natural environment.So far,due to the universality of contact electrification,TENGs can harvest many kinds of mechanical energy generated by CE between various material interfaces,including solid-solid(S-S)interface,solid-liquid(S-L)interface,and even liquidliquid(L-L)/gas(G)interface.After continuous development,S-S and S-L TENG has shown excellent performance in the area of micro/nano energy harvesting,human-computer interaction,sensor,pollutant cleaning and so on.Although a large amount of development has been carried out based on TENG and related applications,there are few related researches on energy harvesting of the L-L interface in contrast to S-S TENG and S-L TENG,the working mechanism of LL TENG is still not fully revealed.Meanwhile,due to ion adsorption and molecular thermal motions,it is quite difficult to achieve complete separation between two liquids and thus,more efforts should be devoted to the study of the energy collection on L-L interface.Here,we first designed a set of liquid-liquid friction nanogenerator,and successfully collected the frictional charge transfer at the pure liquid-liquid interface.then this system is used to study the charge transfer mechanism of liquid-liquid contact electrification.The following are the main contents of the full text:1.We designed an experimental system with strong immunity to environmental electromagnetic interference,which can help to clarify the electrification process between liquid droplets and transformer oil.In this system,deionized(DI)water droplets are dripped freely and continuously into transformer oil,while a TENG with single electrode mode is placed at the bottom of oil.Thus,a complete L-L CE energy collection system is realized.2.Based on this system,we have clarified several important issues.Firstly,during the droplet falling,the charges on the surface of the droplet can gradually accumulates and output charge of-5.3p C can be obtained from our L-L TENG.Secondly,the key parameter for this electrification is the relative falling speed of droplet,which can decide the separation process between droplet and the surrounding transformer oil.Meanwhile,due to the internal circulation of transformer oil,the total amount of transferred charges on the droplet surface finally reaches saturation.3.In addition,we also studied the influence of solute and pH value on L-L CE,and the results show that there is also electrostatic shielding phenomenon,where OH-or H+ ions play an important role in L-L CE.Finally,based on experimental measurement and theoretical derivation,the charge transfer mechanism of the L-L interface and a simple electric double layer(EDL)model are proposed.Finally,based on experimental measurement and theoretical derivation,the charge transfer mechanism of the L-L interface and a simple electric double layer(EDL)model are proposed.