Biomimetic friction layer for nano generator and preparation method thereof

Abstract

The invention discloses a biomimetic friction layer for a nano generator and a preparation method thereof, comprising the following steps: firstly, configuring a fluoropolymer solution; Then the solution is added into the syringe and sprayed on the roller receiver coated with aluminum foil in the form of droplets and fibers under the environment of electrostatic field. Secondly, the fluoropolymerfriction layer was peeled off from the aluminum foil after drying at room temperature and volatilizing the solvent, and three kinds of bionic friction layers were finally obtained. The invention successfully reduces the pore diameter of the porous friction layer to below 400 nm, The biomimetic structure with the thickness reduced to more than ten microns and self-assembled hydrophobic and hydrophilic structures on the upper and lower surfaces of the nanoporous structure significantly improves not only the electrical properties of the material but also the stability and comfort of the materialthrough additional electrostatic effect caused by nanoporous structure. The invention has the advantages of simple preparation process, simple operation, low cost and batch production.

Description

technical field [0001] The invention relates to the technical field of triboelectric power generation, in particular to a friction layer for a nanogenerator with a biomimetic hydrophobic, nanopore and hydrophilic structure and a preparation method thereof. Background technique [0002] In recent years, wearable electronic devices and portable electronic devices have developed rapidly, and are widely used in the fields of Internet of Things, wireless sensor systems, human-computer interaction, health monitoring, security systems, and smart skin; the wide application of wearable and portable electronic devices It also puts forward new requirements for its energy supply unit; traditional chemical batteries are inflexible, heavy, and polluting; some new batteries, such as direct alcohol fuel cells, flexible thin-film solar cells, etc., are either expensive or highly dependent on weather conditions; the above defects limit its application in the field of energy supply for wearabl...

AI Technical Summary

Problems solved by technology

[0004] In terms of improving the output performance of triboelectric nanogenerators, people have done a lot of work in optimizing the triboelectric sequence, surface morphology, surface roughness, surface adsorption, and internal structure of materials; among them, building a porous structure has many advantages : First, the existence of the porous structure can increase the effective contact area of ​​the material, so that more charges can be bound on the surface of the friction layer; second, the porous structure will cause more induced charges inside the material, resulting in additional electrostatic effects; third , the existence of the porous structure will improve the flexibility and compressibility of the material, reduce the effective thickness of the material, and generate a larger relative capacitance when the material is deformed; fourth, compared with the network structure, the porous structure is relatively closed, which can effectively Weaken the dissipation of induced charge; the sacrificial template method is the main method for preparing porous friction layer materials; common sacrificial templates include sugar, sodium chloride, and sodium carbonate; although using the above materials as sacrificial templates makes the output performance of triboelectric nanogenerators However, there are still many defects: first, the resulting porous material is too thick (at least 280 μm), which cannot meet the requirements of light weight and miniaturization; in addition, too thick material will prolong the clearing time of the electrode charge, which is harmful to The improvement of output performance has limitations; second, the pore size of the resulting pore structure is too large (at least 10 μm), and due to the agglomeration of the sacrificial template, the pore structure is unevenly distributed, and the pore size distribution is uneven, resulting in the performance of the nanogenerator. The performance improvement is not obvious; Third, the sacrificial template method is complex, wastes template materials, and is difficult to prepare large-area membrane materials; due to these defects, the optimal current density of triboelectric nanogenerators prepared by this type of method is only 16.7μA / cm 2 ; To solve the second problem above, styrene nanospheres can be used as a sacrificial template to reduce the pore size to 0.5 μm and increase the output current density to 32 μA / cm 2 ; but the high preparation cost and high synthesis difficulty of polystyrene nanospheres limit the practical application of this method; in addition to the sacrificial template method, the use of airgel as a porous friction layer will not cause template waste, and its pore structure size is small. The distribution is relatively uniform, but the thickness of the obtained friction layer is still more than 300μm, and the current density is only 2.15μA / cm 2 ; In addition, the preparation of airgel is difficult, the process is complex, and it is difficult to prepare a large area, which is not conducive to popularization; in addition to the template method and the use of airgel materials, cold-pressed electrospun fiber mat is also a method for preparing porous friction layers; The method can reduce the thickness of the material to tens to tens of microns, so its output current density can be increased to 2.58μA / cm 2 However, the cold pressing method cannot apply uniform stress to the material, which will inevitably cause uneven pore structure distribution and pore size, which limits the further improvement of its output performance; therefore, a new method is needed in the preparation of nanoporous materials with uniform distribution and uniform size. At the same time of structure, under the premise of ensuring the mechanical strength of the material, the thickness of the friction layer is reduced to more than ten microns

[0005] In terms of improving the performance stability of wearable tribogenerators, people consider that the environmental humidity has a great influence on the performance of tribogenerators, so the work of tribogenerators in different humidity environments is often improved by improving the hydrophobicity of the material surface. Stability; since the existence of porous structure will increase the roughness of the material surface, the preparation of porous structure is a feasible method to improve the hydrophobicity of the material; in order to ensure the output performance of the triboelectric nanogenerator, a porous structure with extremely small size is required, but with As the pore size decreases, the surface roughness of the material decreases, and the hydrophobicity weakens accordingly; for example, using sodium carbonate as a template to prepare a friction layer material with a pore size of 15 to 20 μm has a contact angle of 114.4°, while using styrene microspheres as a template The contact angle of the friction layer material with a pore size of 1 μm is reduced to 102° by template preparation; therefore, ensuring that the nanoporous friction layer has high hydrophobicity (contact angle greater than 140°) poses a challenge for the development of new materials

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