High Performance Humidity Generator And Humidity-Triboelectric Composite Generator Based On Humidity Gradient Control

With the coming of the era of Internet of Things,various electronic devices are increasingly used in life.How to power a huge number of electronic devices will be a new challenge.The traditional way is to use batteries to power electronic devices,but this method has many disadvantages.here are many forms of energy in the environment.Capturing this energy and converting it into electricity could be an ideal way to power electronic devices in the future.Humidity generator is a kind of energy conversion device which uses ion concentration difference to generate electricity.The difference in ion concentration in the polymer film of the humidity generator causes the ion to move in a directional way,generating an electric current.Therefore,a key factor to improve the output performance of the humidity generator is to increase the ion concentration difference in the film.For the unsymmetrical moisture generator,increasing the humidity difference between the two sides of the film will increase the ion concentration difference in the film and improve the output of the generator.In this paper,PVA/KOH polymer film was prepared by solution-casting method,and an asymmetrical moisture generator was prepared by the film.KOH has adsorption effect on water molecules,which can increase the humidity difference between the two sides of the film and improve the output performance of the humidity generator.In the relative humidity of 90%environment,the output voltage of PVA/KOH polymer humidity generator is 1.4 V,the output current reaches 590μA,the current density is 49.2μA/cm~2.At the load of 2.2 kΩ,the output power reaches 140 m W/cm~2.Compared with the PVA/KOH polymer humidity generator,the voltage output of the PVA/KOH polymer humidity generator is increased by 2 times and the current output is increased by 7 times.In addition,the effects of PVA/KOH ratio,film thickness and ambient humidity on the output performance of the humidity-generator were investigated.On this basis,by different or the same proportion of PVA/KOH polymer film superposition in A certain order,the multilayer film superposition humidity generator is prepared,the output current is further increased by 0.7 times,the current density reaches 83μA/cm~2.The triboelectric nanogenerator is a kind of energy conversion device which collects the mechanical energy in the conversion environment by using the principle of triboelectric and electrostatic induction.Compared with the output characteristics of humidity generator with low voltage and high current,the output performance of triboelectric nanogenerator usually presents the characteristics of high voltage and low current.The output characteristics of the nanogenerators are attributed to the higher capacitance variation and lower charge carrying capacity of the triboelectric layer in the working state.Although the working principles of triboelectric nanogenerator and humidity generator are different,their output characteristics are highly complementary.If the output charge of the humidity generator can be introduced into the triboelectric nanogenerator,the output enhancement effect can be achieved theoretically.Therefore,we prepared the triboelectric nanogenerator with polyethylene(PE)and metal aluminum as the friction layer,and combined the PVA/KOH polymer humidity generator with the triboelectric nanogenerator to design and fabricate the humidity-triboelectric composite generator.Taking advantage of the high current output characteristics of PVA/KOH polymer humidity generator,charge is added to polyethylene and aluminum to improve the surface charge density of triboelectric materials,thus improving the overall output performance of the composite generator.The output power of the composite generator reaches 27μW,which is greater than the combined output power of the two generators working separately and 4.35μW.The effects of series number of humidity generator and ambient humidity on the output performance of humidity-triboelectric composite generator were investigated.The maximum output voltage and current of the humidity-triboelectric generator are 500 V and 11μA.Compared with the triboelectric nanogenerator,the output voltage and output current are increased by 30 times and 10times.