Energy conversion device, method of making and use thereof

Abstract

The present application relates to an energy conversion device comprising: an upper conductive layer; a lower conductive layer; disposed below the upper conductive layer; at least one piezoelectric micro / nano unit and a fluid disposed between the upper conductive layer and the lower conductive layer; wherein the piezoelectric micro / nano unit has piezoelectric properties and is immersed in the fluid. The present application also relates to a method for preparing the energy conversion device and uses thereof.

Description

[0001] Cross-references to related applications

[0002] This application claims priority and benefit to Chinese Patent Application No. 201911199247.X, filed with the China National Intellectual Property Administration on November 29, 2019, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] This application relates to the energy field. Specifically, this application relates to energy conversion devices, their preparation methods, and their uses. Background Technology

[0004] The world's main energy sources are fossil fuels, nuclear energy, and solar energy. However, the limited availability of fossil fuels, the safety concerns during the use of nuclear energy, and the difficulties in disposing of nuclear waste have made the search for sustainable, green, and pollution-free energy increasingly urgent.

[0005] Molecular thermal motion, as a green and renewable energy source, contains enormous energy. For example, at room temperature (27°C), the average translational kinetic energy of one mole of gas molecules is 3.7 kJ / mol. Because there are vast amounts of liquids and gases on Earth, even if only a portion of this energy can be converted into electricity, it will have a profound impact on the energy landscape. Furthermore, molecular thermal motion is a special type of material motion, fundamentally different from ordinary mechanical motion. It follows the laws of thermodynamics, which mean that thermal motion is a continuous random motion and does not cause destructive impacts on the environment / ecology. In addition, molecular thermal motion does not suffer from the aforementioned problems associated with some other energy sources. Summary of the Invention

[0006] On the one hand, this application provides an energy conversion device, including:

[0007] Upper conductive layer;

[0008] A lower conductive layer; which is disposed below the upper conductive layer;

[0009] At least one piezoelectric micro / nano unit and fluid are disposed between the upper conductive layer and the lower conductive layer;

[0010] The piezoelectric micro / nano units have piezoelectric properties and are immersed in the fluid.

[0011] In some embodiments of the energy conversion device, one end of the piezoelectric micro / nano unit is fixed to the surface of the lower conductive layer facing the upper conductive layer, and the other end is in contact with the upper conductive layer. In some embodiments, the upper conductive layer covers the surface of the lower conductive layer on which the piezoelectric micro / nano unit is fixed. In some embodiments, the piezoelectric micro / nano unit comprises or is composed of piezoelectric micro / nano materials selected from hexagonal wurtzite piezoelectric materials, perovskite piezoelectric materials, polymer piezoelectric materials, and combinations thereof.

[0012] In other embodiments of the energy conversion device, the energy conversion device further includes at least one additional micro / nano unit, one end of which is fixed to the surface of the lower conductive layer facing the upper conductive layer, and one end of which is fixed to the surface of the upper conductive layer facing the lower conductive layer, and the other end of which is a free end, such that the piezoelectric micro / nano unit can contact the additional micro / nano unit when it vibrates randomly; wherein the other end of the additional micro / nano unit is optionally a free end;

[0013] The additional micro / nano units satisfy at least one of the following (i) and (ii):

[0014] (i) The additional micro / nano unit comprises a material capable of forming a Schottky junction or heterojunction with the piezoelectric micro / nano unit or is composed of a material capable of forming a Schottky junction or heterojunction with the piezoelectric micro / nano unit;

[0015] (ii) The surface of the additional micro / nano unit is covered with a shell material; the shell material is a material that can form a Schottky junction or a heterojunction with the piezoelectric micro / nano unit.

[0016] In some embodiments, the piezoelectric micro / nano units on the surface of the lower conductive layer form a cross with the additional micro / nano units on the surface of the upper conductive layer.

[0017] In some embodiments, the micro / nanomaterials in the additional micro / nano unit are the same as or different from the piezoelectric micro / nanomaterials in the piezoelectric micro / nano unit.

[0018] In some embodiments, when the micro / nanomaterial in the additional micro / nano unit is the same as the piezoelectric micro / nanomaterial in the piezoelectric micro / nano unit, the shell material is wrapped on the surface of the additional micro / nano unit.

[0019] In some embodiments, the additional micro / nano units are non-piezoelectric micro / nano units.

[0020] In some embodiments, the piezoelectric micro / nano unit comprises or is composed of piezoelectric semiconductor micro / nano materials.

[0021] In some other embodiments of the energy conversion device, the at least one piezoelectric micro / nano unit is two or more piezoelectric micro / nano units, one end of each piezoelectric micro / nano unit is fixed on each of the two opposing surfaces of the upper conductive layer and the lower conductive layer, and the other end of each piezoelectric micro / nano unit on at least one of the upper and lower conductive layers is a free end, such that when the piezoelectric micro / nano unit with the free end on the at least one conductive layer vibrates randomly, it can contact the piezoelectric micro / nano unit on the other opposing conductive layer;

[0022] Wherein, the surface of the piezoelectric micro / nano unit on the surface of the upper conductive layer or the surface of the piezoelectric micro / nano unit on the surface of the lower conductive layer is covered with a shell material; the shell material is a material that can form a Schottky junction or a heterojunction with the piezoelectric micro / nano unit.

[0023] In some embodiments, the piezoelectric micro / nano units on the surface of the upper conductive layer and the piezoelectric micro / nano units on the surface of the lower conductive layer form a cross.

[0024] In some embodiments, the piezoelectric micro / nano unit comprises or is composed of piezoelectric semiconductor micro / nano materials.

[0025] On the other hand, this application provides a method for manufacturing an energy conversion device, comprising:

[0026] Provide an upper conductive layer;

[0027] A lower conductive layer is provided and disposed below the upper conductive layer;

[0028] At least one piezoelectric micro / nano unit and a fluid are disposed between the upper conductive layer and the lower conductive layer;

[0029] The piezoelectric micro / nano units are immersed in the fluid.

[0030] In some embodiments of the method, the method further includes:

[0031] Fixing step: Fixing one end of the piezoelectric micro / nano unit to the surface of the lower conductive layer; in some embodiments, the fixing step includes growing the piezoelectric micro / nano unit on the surface of the lower conductive layer; in some embodiments, the growth is performed along an orientation perpendicular to the surface of the conductive layer;

[0032] Assembly steps: The other end of the fixed piezoelectric micro / nano unit is brought into contact with the upper conductive layer; in some embodiments, the assembly steps include covering the upper conductive layer onto the surface of the lower conductive layer on which the piezoelectric micro / nano unit is grown;

[0033] Fluid introduction step: Optionally, the fluid is introduced before, after, or during the assembly step; in some embodiments, the fluid introduction step includes introducing the fluid to the surface of the lower conductive layer where the piezoelectric micro / nano units are fixed before the assembly step; in some embodiments, the fluid introduction step includes introducing the fluid between the upper and lower conductive layers after the assembly step; in some embodiments, the fluid introduction step includes performing the assembly step in an atmosphere of the fluid as a gas, thereby introducing the fluid during the assembly process; in some embodiments, the fluid introduction step includes introducing a liquid between the upper and lower conductive layers after the assembly step;

[0034] In some embodiments, the method further includes a device packaging step; in some embodiments, the device packaging step includes physical packaging or chemical packaging; in some embodiments, the packaging is mechanical packaging or packaging using adhesives or tapes.

[0035] In some embodiments, the piezoelectric micro / nano unit comprises or is composed of piezoelectric micro / nano materials selected from hexagonal wurtzite piezoelectric materials, perovskite piezoelectric materials, polymer piezoelectric materials, and combinations thereof;

[0036] In some embodiments, when the piezoelectric micro / nano unit comprises a piezoelectric micro / nano material selected from perovskite piezoelectric materials, polymer piezoelectric materials, and combinations thereof, the device is polarized prior to the fluid introduction step; in some embodiments, the polarization step includes applying an electric field between the upper conductive layer and the lower conductive layer, causing it to spontaneously polarize and preferentially align along the direction of the electric field under the action of the electric field.

[0037] In other embodiments of the method, the device further includes additional micro / nano units, wherein the additional micro / nano units satisfy at least one of the following (i) and (ii):

[0038] (i) The additional micro / nano unit comprises a material capable of forming a Schottky junction or heterojunction with the piezoelectric micro / nano unit or is composed of a material capable of forming a Schottky junction or heterojunction with the piezoelectric micro / nano unit;

[0039] (ii) The surface of the additional micro / nano unit is covered with a shell material; the shell material is a material that can form a Schottky junction or a heterojunction with the piezoelectric micro / nano unit;

[0040] The method further includes:

[0041] Fixing step: One end of the piezoelectric micro / nano unit is fixed to the surface of the lower conductive layer, and one end of the additional micro / nano unit is fixed to the surface of the upper conductive layer, wherein the other end of the piezoelectric micro / nano unit is a free end, and the other end of the additional micro / nano unit is optionally a free end; in some embodiments, the fixing step includes growing the additional micro / nano unit and the piezoelectric micro / nano unit on the surface of the upper conductive layer and the surface of the lower conductive layer, respectively; in some embodiments, the growth is carried out along an orientation perpendicular to the surface of the conductive layer;

[0042] Optional wrapping step: When the additional micro / nano unit does not satisfy (i) above, the shell material is wrapped around the surface of the additional micro / nano unit; wherein the shell material is a material capable of forming a Schottky junction or heterojunction with the piezoelectric micro / nano unit;

[0043] Assembly steps: The piezoelectric micro / nano units fixed on the lower conductive layer are assembled with the additional micro / nano units fixed on the upper conductive layer facing each other, so that the piezoelectric micro / nano units can contact the additional micro / nano units when they vibrate randomly; wherein, when the additional micro / nano units do not satisfy the above (i), the upper conductive layer with the additional micro / nano units fixed is the upper conductive layer with the additional micro / nano units fixed and encased in the shell material.

[0044] In some embodiments, the assembly step includes: placing a pad around the surface of the lower conductive layer on which the piezoelectric micro / nano units are fixed, wherein the thickness of the pad, or the thickness of the pad when the pad is compressed due to force, is not less than the distance from the free end of the piezoelectric micro / nano unit to the surface of the lower conductive layer on which the piezoelectric micro / nano unit is fixed, and is less than the sum of the distance from the free end of the piezoelectric micro / nano unit to the surface of the lower conductive layer on which the piezoelectric micro / nano unit is fixed and the distance from the free end of the additional micro / nano unit to the surface of the upper conductive layer on which the additional micro / nano unit is fixed; and placing the upper conductive layer on which the additional micro / nano units are fixed.

[0045] Fluid introduction step: Optionally, the fluid is introduced before or during the assembly step; in some embodiments, the fluid introduction step includes introducing the fluid to the surface of the lower conductive layer where the piezoelectric micro / nano units are fixed and the surface of the upper conductive layer where the additional micro / nano units are fixed before the assembly step; in some embodiments, the fluid introduction step includes introducing the fluid as a liquid into the entire space surrounded by the pad after the pad is placed, and then placing the upper conductive layer where the additional micro / nano units are fixed on the pad, thereby introducing the fluid during the assembly step; wherein when the additional micro / nano units do not satisfy the above (i), the surface of the upper conductive layer where the additional micro / nano units are fixed is the surface of the upper conductive layer where the additional micro / nano units are fixed and enclosed by the shell material; in some embodiments, the fluid introduction step includes performing the assembly step in an atmosphere of the fluid as a gas, thereby introducing the fluid during the assembly step.

[0046] In some embodiments, the method further includes a device packaging step; in some embodiments, the device packaging step includes physical packaging or chemical packaging; in some embodiments, the packaging is mechanical packaging or packaging using adhesives or tapes.

[0047] In some embodiments, the assembly is performed such that the additional micro / nano units on the surface of the upper conductive layer form a fork with the piezoelectric micro / nano units on the surface of the lower conductive layer.

[0048] In some embodiments, the micro / nanomaterials in the additional micro / nano unit are the same as or different from the piezoelectric micro / nanomaterials in the piezoelectric micro / nano unit.

[0049] In some embodiments, when the micro / nanomaterial in the additional micro / nano unit is the same as the piezoelectric micro / nanomaterial in the piezoelectric micro / nano unit, the shell material is wrapped on the surface of the additional micro / nano unit.

[0050] In some embodiments, the additional micro / nano units are non-piezoelectric micro / nano units.

[0051] In some embodiments, the piezoelectric micro / nano unit comprises or is composed of piezoelectric semiconductor micro / nano materials.

[0052] In some embodiments of any of the foregoing aspects, the two surfaces of the upper conductive layer and the lower conductive layer that are opposite to each other are substantially parallel.

[0053] In some embodiments of any of the foregoing aspects, the micro / nano units are micro / nano arrays each time they appear.

[0054] In some embodiments of any of the foregoing aspects, the piezoelectric micro / nano unit and the additional micro / nano unit are each at least partially or completely immersed in the fluid.

[0055] In some embodiments of any of the foregoing aspects, the fluid at least partially or completely fills the space between the two opposing surfaces of the upper conductive layer and the lower conductive layer.

[0056] In some embodiments of any of the foregoing aspects, the fixing is performed along an orientation perpendicular to the surface of the conductive layer.

[0057] In some embodiments of any of the foregoing aspects, the energy conversion device further includes an encapsulation layer disposed on the outer periphery of the device. In some embodiments of any of the foregoing aspects, the encapsulation layer comprises an adhesive. In some embodiments of any of the foregoing aspects, the adhesive is selected from epoxy resins, silicones, EVA, and combinations thereof.

[0058] In some embodiments of any of the foregoing aspects, the energy conversion device further includes leads; the leads are respectively led out from the upper conductive layer and the lower conductive layer.

[0059] In some embodiments of any of the foregoing aspects, the fluid is a gas or a liquid.

[0060] In some embodiments of any of the foregoing aspects, the gas is a compressed and / or heated gas.

[0061] In some embodiments of any of the foregoing aspects, the gas is a heavy molecular gas. In some embodiments of any of the foregoing aspects, the gas is a compressed and / or heated heavy molecular gas.

[0062] In some embodiments of any of the foregoing aspects, the gas is air, compressed air, xenon, oxygen, nitrogen, hydrogen, and combinations thereof.

[0063] In some embodiments of any of the foregoing aspects, the fluid is a heated liquid.

[0064] In some embodiments of any of the foregoing aspects, the dielectric constant of the liquid is less than 80, less than 40, less than 10, less than 4.0, less than 3.0, less than 2.5, or less than 2.0.

[0065] In some embodiments of any of the foregoing aspects, the viscosity of the liquid is less than 80000 mPa·s, less than 8000 mPa·s, less than 800 mPa·s, less than 80 mPa·s, less than 8 mPa·s, or less than 0.8 mPa·s.

[0066] In some embodiments of any of the foregoing aspects, the liquid is a nonpolar or weakly polar liquid.

[0067] In some embodiments of any of the foregoing aspects, the liquid is a low-viscosity liquid.

[0068] In some embodiments of any of the foregoing aspects, the liquid is a non-polar or weakly polar liquid with low viscosity.

[0069] In some embodiments of any of the foregoing aspects, the liquid is selected from dimethyl carbonate, diethyl carbonate, tetrachloroethylene, cyclopentene, n-octane, n-hexane, ethanol, dichloroethane, and combinations thereof.

[0070] In some embodiments of any of the foregoing aspects, the upper conductive layer and the lower conductive layer comprise a conductive or non-conductive substrate; in some embodiments, the upper conductive layer and the lower conductive layer each independently comprise a material selected from the group consisting of metals, carbon materials, semiconductor materials, and combinations thereof; in some embodiments, the upper conductive layer and the lower conductive layer each independently comprise a material selected from the group consisting of Au, Pt, Ag, Cu, Zn, ITO, FTO, C, and combinations thereof.

[0071] In some embodiments of any of the foregoing aspects, the upper conductive layer and the lower conductive layer are each independently a sheet-like or nanostructure covered with a conductive film. In some embodiments of any of the foregoing aspects, the nanostructure is a nanogroove, a nanoarray, or a combination thereof.

[0072] In some embodiments of any of the foregoing aspects, the minimum radial dimension of at least a portion of the cross-section of each nanounit along its extension direction is 1 nm to 10 μm, 10 nm to 1 μm, 20 nm to 300 nm, 10 nm to 500 nm, or 10 nm to 100 nm.

[0073] In some embodiments of any of the foregoing aspects, the gaps between the nanounits in the nanoarray are 5nm~20μm, 20nm-5μm, 50nm-1μm, 80nm-500nm, or 100nm-300nm.

[0074] In some embodiments of any of the foregoing aspects, the piezoelectric micro / nano unit and the additional micro / nano unit are each independently a nanorod, nanosheet, nanowire, nanoribbon, nanotube, nanohelix, or a combination thereof.

[0075] In some embodiments of any of the foregoing aspects, the piezoelectric semiconductor micro / nanomaterial is selected from hexagonal wurtzite piezoelectric materials.

[0076] In some embodiments of any of the foregoing aspects, the hexagonal wurtzite piezoelectric material is selected from ZnO, GaN, ZnS, CdS, InN, InGaN, CdTe, CdSe, ZnSnO3, and combinations thereof.

[0077] In some embodiments of any of the foregoing aspects, the perovskite piezoelectric material has the general formula ABO3; wherein A is a rare earth or alkaline earth metal ion and B is a transition metal ion.

[0078] In some embodiments of any of the foregoing aspects, the perovskite piezoelectric material is selected from lead zirconate titanate (PZT), barium titanate (BaTiO3), potassium sodium niobate (KNN), and combinations thereof.

[0079] In some embodiments of any of the foregoing aspects, the polymer piezoelectric material is selected from polyvinylidene fluoride (PVDF) and polydimethylsiloxane (PDMS).

[0080] In some embodiments of any of the foregoing aspects, the piezoelectric micro / nano unit is a ZnO nanoarray.

[0081] In some embodiments of any of the foregoing aspects, the shell material is a metallic material, and the work function of the metallic material is greater than or less than the work function of the piezoelectric semiconductor micro / nano material.

[0082] In some embodiments of any of the foregoing aspects, the shell material is another semiconductor material capable of forming a heterojunction with the piezoelectric semiconductor micro / nanomaterial.

[0083] In some embodiments of any of the foregoing aspects, the shell material is a metallic material selected from Au, Pt, Ag, Ti, Al, and combinations thereof.

[0084] In some embodiments of any of the foregoing aspects, the shell material is a semiconductor material selected from CuO, silicon wafers, Cu2O, NiO, Co3O4, and combinations thereof.

[0085] In some embodiments of any of the foregoing aspects, the shell material is formed by magnetron sputtering, electron beam evaporation, thermal deposition, or sol-gel deposition on the surface of the upper conductive layer to which the nanounits are fixed.

[0086] On the other hand, this application provides articles, devices, or power supply devices that include the energy conversion apparatus described in this disclosure. In some embodiments, the articles or devices are powered by the energy conversion apparatus.

[0087] In addition, this application provides the use of the energy conversion device described in this disclosure in energy conversion and harvesting, such as energy storage, sensors, wearable devices, and mobile devices. Attached Figure Description

[0088] Figure 1 This is a schematic diagram of the energy conversion device in Example 1.

[0089] Figure 2 The current-voltage curves of the energy conversion device of Example 1 are shown.

[0090] Figure 3 The voltage and current outputs of the energy conversion device of Embodiment 1 are shown.

[0091] Figure 4 The current and voltage output curves of the energy conversion device in Example 2 are shown.

[0092] Figure 5 The cyclic voltammetry curves of the energy conversion device of Example 2 are shown.

[0093] Figure 6 The current and voltage output curves of the energy conversion device in Example 3 are shown.

[0094] Figure 7 This is a schematic diagram of the energy conversion device in Example 4.

[0095] Figure 8 The voltage and current output of the energy conversion device of Example 5 at different temperatures are shown.

[0096] Detailed description

[0097] definition

[0098] The following definitions and methods are provided to better define this application and to guide those skilled in the art in its practice. Unless otherwise stated, the terms are to be understood in accordance with their conventional usage by those skilled in the art.

[0099] As used herein, the terms “comprising” and “including” should be interpreted as inclusive and open-ended, not exclusive. Specifically, when used in the specification and claims, the terms “comprising” and “including” and their variations mean to include the specified features, steps, or components. These terms should not be construed as excluding the presence of other features, steps, or components.

[0100] As used herein, the terms "optional" or "optionally" mean that the events or circumstances described below may, but are not required to, occur, including both when they do occur and when they do not. They represent an option and may be used interchangeably with "or".

[0101] Spatial relative terms, such as “below,” “under,” “lower,” “above,” “upper,” “above,” etc., may be used herein for descriptive purposes and thereby to describe the relationship between one element and another, as illustrated in the accompanying drawings. In addition to the directions described in the drawings, spatial relative terms are intended to also include different orientations of the equipment in use, operation, and / or manufacture. For example, if the equipment in the drawings is flipped, an element described as being “above” or “above” other elements or features would be positioned “below” said other elements or features. Thus, the exemplary term “above” can include both upward and downward directions. Furthermore, the equipment may be oriented in other ways (e.g., rotated 90 degrees or in other directions), and in such cases, the spatial relative descriptive symbols used herein are interpreted accordingly.

[0102] The term "polymer piezoelectric material" as used in this article usually refers to piezoelectric materials composed of high molecular polymers.

[0103] The term “micro / nano unit” as used in this article refers to micron units, nano units, or combinations thereof.

[0104] The term "heavy molecular gas" as used in this article refers to a gas with a relative molecular weight of not less than 25 (e.g., not less than 25, not less than 40, not less than 60, not less than 80, not less than 100).

[0105] Wherever a range of values ​​is given herein, the range includes its endpoints, as well as all individual integers and fractions within the range, and also includes each narrower range formed by all the various possible combinations of those endpoints and internal integers and fractions, to form a subgroup of a larger group of values ​​within the same extent as each of those narrower ranges is explicitly given. For example, the minimum radial dimension of at least a portion of the cross-section of each nanounit along its extension direction being 1 nm to 10 μm means that the minimum radial dimension can be, for example, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, 21 nm, 22 nm, 24 nm, 28 nm, 30 nm, 32 nm, 35 nm, 38 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, 210 nm, 220 nm, 230 nm, 240 nm, 250 nm, 260 nm. nm, 270 nm, 280 nm, 290 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm, etc., and the ranges formed by them.

[0106] On the one hand, this application provides an energy conversion device, including:

[0107] Upper conductive layer;

[0108] A lower conductive layer; which is disposed below the upper conductive layer;

[0109] At least one piezoelectric micro / nano unit and fluid are disposed between the upper conductive layer and the lower conductive layer;

[0110] The piezoelectric micro / nano units have piezoelectric properties and are immersed in the fluid.

[0111] The basic principle of the energy conversion device of the present invention is as follows: When a piezoelectric material with a piezoelectric effect is placed in a fluid, due to the thermal motion of the fluid molecules, the piezoelectric material undergoes Brownian motion, random vibration, and deformation, thereby generating a potential difference on the material surface. This potential difference is then led out through electrodes to form a detectable current in an external circuit. The potential difference of the piezoelectric material originates at least partially from the thermal motion of the molecules. The piezoelectric material may include various piezoelectric materials capable of generating a piezoelectric effect in the art, including but not limited to one or more combinations of hexagonal wurtzite piezoelectric materials, perovskite piezoelectric materials, and polymer piezoelectric materials.

[0112] In some embodiments of the energy conversion device, one end of the piezoelectric micro / nano unit is fixed to the surface of the lower conductive layer facing the upper conductive layer, and the other end is in contact with the upper conductive layer. In some embodiments, the upper conductive layer covers the surface of the lower conductive layer on which the piezoelectric micro / nano unit is fixed. In some embodiments, the piezoelectric micro / nano unit comprises or is composed of piezoelectric micro / nano materials selected from hexagonal wurtzite piezoelectric materials, perovskite piezoelectric materials, polymer piezoelectric materials, and combinations thereof.

[0113] The upper conductive layer (e.g., aluminum foil) on the surface of the lower conductive layer on which the piezoelectric micro / nano unit is fixed can be directly used as the upper electrode or combined with other electrode materials as the upper electrode. The lower conductive layer (e.g., FTO conductive surface) can be directly used as the lower electrode. The upper and lower electrodes are respectively led out by leads (e.g., copper wire) to form a detectable current in the external circuit.

[0114] In other embodiments of the energy conversion device, the energy conversion device further includes at least one additional micro / nano unit, one end of which is fixed to the surface of the lower conductive layer facing the upper conductive layer, and one end of which is fixed to the surface of the upper conductive layer facing the lower conductive layer, and the other end of which is a free end, such that the piezoelectric micro / nano unit can contact the additional micro / nano unit when it vibrates randomly; wherein the other end of the additional micro / nano unit is optionally a free end;

[0115] The additional micro / nano units satisfy at least one of the following (i) and (ii):

[0116] (i) The additional micro / nano unit comprises a material capable of forming a Schottky junction or heterojunction with the piezoelectric micro / nano unit or is composed of a material capable of forming a Schottky junction or heterojunction with the piezoelectric micro / nano unit;

[0117] (ii) The surface of the additional micro / nano unit is covered with a shell material; the shell material is a material that can form a Schottky junction or a heterojunction with the piezoelectric micro / nano unit.

[0118] In some embodiments, the piezoelectric micro / nano units on the surface of the lower conductive layer form a cross with the additional micro / nano units on the surface of the upper conductive layer.

[0119] In some embodiments, the micro / nanomaterials in the additional micro / nano unit are the same as or different from the piezoelectric micro / nanomaterials in the piezoelectric micro / nano unit.

[0120] In some embodiments, when the micro / nanomaterial in the additional micro / nano unit is the same as the piezoelectric micro / nanomaterial in the piezoelectric micro / nano unit, the shell material is wrapped on the surface of the additional micro / nano unit.

[0121] In some embodiments, the additional micro / nano units are non-piezoelectric micro / nano units.

[0122] In some embodiments, the piezoelectric micro / nano unit comprises or is composed of piezoelectric semiconductor micro / nano materials.

[0123] The shell material can be directly used as the upper electrode, and the lower conductive layer (e.g., a metal substrate, such as a Zn sheet) can be directly used as the lower electrode. The upper and lower electrodes are respectively led out by leads to form a detectable current in the external circuit.

[0124] In some other embodiments of the energy conversion device, the at least one piezoelectric micro / nano unit is two or more piezoelectric micro / nano units. One end of each piezoelectric micro / nano unit is fixed on one of the two opposing surfaces of the upper conductive layer and the lower conductive layer (i.e., one end of a portion of the piezoelectric micro / nano units is fixed on the upper conductive layer, and one end of another portion of the piezoelectric micro / nano units is fixed on the surface of the lower conductive layer facing the upper conductive layer). The other end of each piezoelectric micro / nano unit on at least one of the upper and lower conductive layers is a free end, such that when the piezoelectric micro / nano unit with the free end on the at least one conductive layer vibrates randomly, it can contact the piezoelectric micro / nano unit on the opposite conductive layer.

[0125] Wherein, the surface of the piezoelectric micro / nano unit on the surface of the upper conductive layer or the surface of the piezoelectric micro / nano unit on the surface of the lower conductive layer is covered with a shell material; the shell material is a material that can form a Schottky junction (e.g., a metal shell material) or a heterojunction with the piezoelectric micro / nano unit (e.g., CuO, silicon wafer, Cu2O, NiO, Co3O4, etc. shell materials).

[0126] In some embodiments, the piezoelectric micro / nano units on the surface of the upper conductive layer and the piezoelectric micro / nano units on the surface of the lower conductive layer form a cross.

[0127] In some embodiments, the piezoelectric micro / nano unit comprises or is composed of piezoelectric semiconductor micro / nano materials.

[0128] The shell material can be directly used as the upper electrode, and the lower conductive layer (e.g., a metal substrate, such as a Zn sheet) can be directly used as the lower electrode. The upper and lower electrodes are respectively led out by leads. The potential difference generated by the semiconductor piezoelectric material is passed through the upper electrode. By utilizing the Schottky junction at the metal-semiconductor interface or the PN junction between semiconductors, which has unidirectional conduction rectification characteristics, unidirectional DC output is achieved.

[0129] In some embodiments, the lower conductive layer (e.g., a metal substrate) is polished.

[0130] On the other hand, this application provides a method for manufacturing an energy conversion device, comprising:

[0131] Provide an upper conductive layer;

[0132] A lower conductive layer is provided and disposed below the upper conductive layer;

[0133] At least one piezoelectric micro / nano unit and a fluid are disposed between the upper conductive layer and the lower conductive layer;

[0134] The piezoelectric micro / nano units are immersed in the fluid.

[0135] In some embodiments of the method, the method further includes:

[0136] Fixing step: Fixing one end of the piezoelectric micro / nano unit to the surface of the lower conductive layer; in some embodiments, the fixing step includes growing the piezoelectric micro / nano unit on the surface of the lower conductive layer; in some embodiments, the growth is performed along an orientation perpendicular to the surface of the conductive layer;

[0137] Assembly steps: The other end of the fixed piezoelectric micro / nano unit is brought into contact with the upper conductive layer; in some embodiments, the assembly steps include covering the upper conductive layer onto the surface of the lower conductive layer on which the piezoelectric micro / nano unit is grown;

[0138] Fluid introduction step: The fluid may optionally be introduced before, after, or during the assembly step; in some embodiments, the fluid introduction step includes introducing the fluid to the surface of the lower conductive layer where the piezoelectric micro / nano units are fixed before the assembly step; in some embodiments, the fluid introduction step includes introducing the fluid between the upper and lower conductive layers after the assembly step; in some embodiments, the fluid introduction step includes performing the assembly step in an atmosphere of the fluid as a gas, thereby introducing the fluid during the assembly process; in some embodiments, the fluid introduction step includes introducing (e.g., dropwise addition) a liquid between the upper and lower conductive layers after the assembly step;

[0139] In some embodiments, the method may further include a device packaging step; in some embodiments, the device packaging step includes physical packaging or chemical packaging; in some embodiments, the packaging is mechanical packaging or packaging using adhesives or tapes.

[0140] In some embodiments, the piezoelectric micro / nano unit may comprise or be composed of piezoelectric micro / nano materials selected from hexagonal wurtzite piezoelectric materials, perovskite piezoelectric materials, polymer piezoelectric materials, and combinations thereof;

[0141] In some embodiments, when the piezoelectric micro / nano unit comprises a piezoelectric micro / nano material selected from perovskite piezoelectric materials, polymer piezoelectric materials, and combinations thereof, the device is polarized prior to the fluid introduction step; in some embodiments, the polarization step includes applying an electric field between the upper conductive layer and the lower conductive layer, causing it to spontaneously polarize and preferentially align along the direction of the electric field under the action of the electric field.

[0142] In other embodiments of the method, the device further includes additional micro / nano units, wherein the additional micro / nano units satisfy at least one of the following (i) and (ii):

[0143] (i) The additional micro / nano unit comprises a material capable of forming a Schottky junction or heterojunction with the piezoelectric micro / nano unit or is composed of a material capable of forming a Schottky junction or heterojunction with the piezoelectric micro / nano unit;

[0144] (ii) The surface of the additional micro / nano unit is covered with a shell material; the shell material is a material that can form a Schottky junction or a heterojunction with the piezoelectric micro / nano unit;

[0145] The method further includes:

[0146] Fixing Step: One end of the piezoelectric micro / nano unit is fixed to the surface of the lower conductive layer, and one end of the additional micro / nano unit is fixed to the surface of the upper conductive layer, wherein the other end of the piezoelectric micro / nano unit is a free end, and the other end of the additional micro / nano unit is optionally a free end, for example, the other end of the additional micro / nano unit can be a free end, or it can not be a free end (e.g., in contact with the upper conductive layer); in some embodiments, the fixing step includes growing the additional micro / nano unit and the piezoelectric micro / nano unit on the surface of the upper conductive layer and the surface of the lower conductive layer, respectively; in some embodiments, the growth is oriented perpendicular to the surface of the conductive layer.

[0147] Optional wrapping step: When the additional micro / nano unit does not satisfy (i) above, the shell material is wrapped around the surface of the additional micro / nano unit; wherein the shell material is a material capable of forming a Schottky junction or heterojunction with the piezoelectric micro / nano unit;

[0148] Assembly steps: The piezoelectric micro / nano units fixed on the lower conductive layer are assembled with the additional micro / nano units fixed on the upper conductive layer facing each other, so that the piezoelectric micro / nano units can contact the additional micro / nano units when they vibrate randomly; wherein, when the additional micro / nano units do not satisfy the above (i), the upper conductive layer with the additional micro / nano units fixed is the upper conductive layer with the additional micro / nano units fixed and encased in the shell material.

[0149] In some embodiments, the assembly step includes: placing a pad around the surface of the lower conductive layer on which the piezoelectric micro / nano units are fixed, wherein the thickness of the pad, or the thickness of the pad when the pad is compressed due to force, is not less than the distance from the free end of the piezoelectric micro / nano unit to the surface of the lower conductive layer on which the piezoelectric micro / nano unit is fixed, and is less than the sum of the distance from the free end of the piezoelectric micro / nano unit to the surface of the lower conductive layer on which the piezoelectric micro / nano unit is fixed and the distance from the free end of the additional micro / nano unit to the surface of the upper conductive layer on which the additional micro / nano unit is fixed; and placing the upper conductive layer on which the additional micro / nano units are fixed.

[0150] Fluid introduction step: Optionally, the fluid is introduced before or during the assembly step; in some embodiments, the fluid introduction step includes introducing the fluid to the surface of the lower conductive layer where the piezoelectric micro / nano units are fixed and the surface of the upper conductive layer where the additional micro / nano units are fixed before the assembly step; in some embodiments, the fluid introduction step includes introducing the fluid as a liquid into the entire space surrounded by the pad after the pad is placed, and then placing the upper conductive layer where the additional micro / nano units are fixed on the pad, thereby introducing the fluid during the assembly step; wherein when the additional micro / nano units do not satisfy the above (i), the surface of the upper conductive layer where the additional micro / nano units are fixed is the surface of the upper conductive layer where the additional micro / nano units are fixed and enclosed by the shell material; in some embodiments, the fluid introduction step includes performing the assembly step in an atmosphere of the fluid as a gas, thereby introducing the fluid during the assembly step.

[0151] In some embodiments, the method further includes a device packaging step; in some embodiments, the device packaging step includes physical packaging or chemical packaging; in some embodiments, the packaging is mechanical packaging or packaging using adhesives or tapes.

[0152] In some embodiments, the assembly is performed such that the additional micro / nano units on the surface of the upper conductive layer form a fork with the piezoelectric micro / nano units on the surface of the lower conductive layer.

[0153] In some embodiments, the micro / nanomaterials in the additional micro / nano unit are the same as or different from the piezoelectric micro / nanomaterials in the piezoelectric micro / nano unit.

[0154] In some embodiments, when the micro / nanomaterial in the additional micro / nano unit is the same as the piezoelectric micro / nanomaterial in the piezoelectric micro / nano unit, the shell material is wrapped on the surface of the additional micro / nano unit.

[0155] In some embodiments, the additional micro / nano units are non-piezoelectric micro / nano units.

[0156] In some embodiments, the piezoelectric micro / nano unit comprises or is composed of piezoelectric semiconductor micro / nano materials.

[0157] In some embodiments of any of the foregoing aspects, the two surfaces of the upper conductive layer and the lower conductive layer that are opposite to each other are substantially parallel.

[0158] In some embodiments of any of the foregoing aspects, the micro / nano units are micro / nano arrays each time they appear. For example, both the piezoelectric micro / nano units and the additional micro / nano units described above are nano arrays.

[0159] In some embodiments of any of the foregoing aspects, the piezoelectric micro / nano unit and the additional micro / nano unit are each at least partially or completely immersed in the fluid.

[0160] In some embodiments of any of the foregoing aspects, the fluid at least partially or completely fills the space between the two opposing surfaces of the upper conductive layer and the lower conductive layer.

[0161] In some embodiments of any of the foregoing aspects, the fixing is performed along an orientation perpendicular to the surface of the conductive layer. When one end of the piezoelectric nanostructure is fixed to the lower conductive layer, which serves as the lower electrode of the energy conversion device, and the other end is a free end, the strain at the free end will be more sufficient when the piezoelectric material is placed in a fluid due to the fixed end.

[0162] In some embodiments of any of the foregoing aspects, the energy conversion device further includes an encapsulation layer disposed over the entire outer periphery of the device. In some embodiments of any of the foregoing aspects, the encapsulation layer comprises an adhesive. In some embodiments of any of the foregoing aspects, the adhesive may be selected from epoxy resins, silicones, EVA, and combinations thereof.

[0163] In some embodiments of any of the foregoing aspects, the energy conversion device further includes leads; the leads are respectively led out from the upper conductive layer and the lower conductive layer.

[0164] In some embodiments of any of the foregoing aspects, the fluid may be a gas or a liquid.

[0165] In some embodiments of any of the foregoing aspects, the gas may be a compressed and / or heated gas.

[0166] In some embodiments of any of the foregoing aspects, the gas may be a heavy molecular gas. In some embodiments of any of the foregoing aspects, the gas may be a compressed and / or heated heavy molecular gas.

[0167] In some embodiments of any of the foregoing aspects, the gas is air, compressed air, xenon, oxygen, nitrogen, hydrogen, and combinations thereof.

[0168] In some embodiments of any of the foregoing aspects, the fluid may be a heated liquid.

[0169] In some embodiments of any of the foregoing aspects, the liquid is a nonpolar or weakly polar liquid with low viscosity. When the fluid is a liquid, it is typically a nonpolar or weakly polar substance with a low dielectric constant, for example, less than 80 (e.g., less than 79, less than 78, less than 77, less than 76, less than 75, less than 74, less than 73, less than 72, less than 71, less than 70, less than 69, less than 68, less than 67, less than 66, less than 65, less than 64, less than 63, less than 62, less than 61, less than 60, less than 59, less than 58, less than 57, less than 56, less than 55, less than 54, less than 53, less than 52, less than 51, less than 50, less than 49, less than 48, less than 47, less than 46, less than 45, less than 44, less than 43, less than 42, less than 41, less than 40). <39, <38, <37, <36, <35, <34, <33, <32, <31, <30, <29, <28, <27, <26, <25, <24, <23, <22, <21, <20, <19, <18, <17, <16, <15, <14, <13, <12, <11, <10, <9, <8, <7, <6, <5, <4, <3.8, <3.5, <3, <2.7, <2.5, or <2, etc.), <40, <10, <4.0, <3.0, <2.5, or <2.0, thus avoiding the presence of freely moving ions in the solution, and typically having a low viscosity, for example less than 80,000 mPa·s (e.g., 80,000 mPa·s, 70,000 mPa·s, 60,000 mPa·s, 50,000 mPa·s, 40,000 mPa·s, 30,000 mPa·s, 20,000 mPa·s, 10,000 mPa·s, 9,000 mPa·s, 8,000 mPa·s, 7,000 mPa·s, 6,000 mPa·s, 5,000 mPa·s, 4,000 mPa·s, 3,000 mPa·s, 20,000 mPa·s, 10,000 mPa·s, 900 mPa·s, 800 mPa·s, 700 mPa·s, 600 mPa·s, 500 mPa·s, 4000 mPa·s, 3000 mPa·s, 2000 mPa·s, 1000 mPa·s, 900 mPa·s, 800 mPa·s, 700 mPa·s, 600 mPa·s, 500 mPa·s, 4000 mPa·s). (e.g., 300 mPa·s, 200 mPa·s, 100 mPa·s, 90 mPa·s, 80 mPa·s, 70 mPa·s, 60 mPa·s, 50 mPa·s, 40 mPa·s, 30 mPa·s, 20 mPa·s, 10 mPa·s, 9 mPa·s, 8 mPa·s, 7 mPa·s, 6 mPa·s, 5 mPa·s, 4 mPa·s, 3 mPa·s, 2 mPa·s, 1 mPa·s, 0.9 mPa·s, 0.8 mPa·s, 0.7 mPa·s, 0.6 mPa·s, 0.5 mPa·s, 0.4 mPa·s or 0.3 mPa·s, etc.), less than 8000 mPa·s, less than 80 mPa·s, less than 8 mPa·s, or less than 0.8 mPa·s. The pressure should be set at mPa·s to facilitate molecular thermal motion.

[0170] In some embodiments of any of the foregoing aspects, the liquid is selected from dimethyl carbonate, diethyl carbonate, tetrachloroethylene, cyclopentene, n-octane, n-hexane, ethanol, dichloroethane, and combinations thereof.

[0171] In some embodiments of any of the foregoing aspects, the upper conductive layer and the lower conductive layer comprise a conductive or non-conductive substrate; in some embodiments, the upper conductive layer and the lower conductive layer each independently comprise a material selected from the group consisting of metals, carbon materials, semiconductor materials, and combinations thereof; in some embodiments, the upper conductive layer and the lower conductive layer each independently comprise a material selected from the group consisting of Au, Pt, Ag, Cu, Zn, ITO, FTO, C, and combinations thereof. When the substrate is a non-conductive substrate, the conductive layer can be obtained by forming the aforementioned metal, carbon, or semiconductor materials on the substrate.

[0172] In some embodiments of any of the foregoing aspects, the upper conductive layer and the lower conductive layer are each independently a sheet-like or nanostructure covered with a conductive film. In some embodiments of any of the foregoing aspects, the nanostructure is a nanogroove, a nanoarray, or a combination thereof.

[0173] In some embodiments of any of the foregoing aspects, the minimum radial dimension of at least a portion of the cross-section of each nanounit along its extension direction is 1 nm to 10 μm (e.g., 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, 21 nm, 22 nm, 24 nm, 28 nm, 30 nm, 32 nm, 35 nm, 38 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, 210 nm, 220 nm, 230 nm, 240 nm, 250 nm, 260 nm). The piezoelectric material can have various diameters and lengths, ranging from 270 nm, 280 nm, 290 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm, etc., to 10 nm-1 μm, 20 nm-300 nm, 10 nm-500 nm, or 10 nm-100 nm. However, the cross-sectional shape, diameter, or length of the piezoelectric material can vary depending on the material and manufacturing process. Those skilled in the art can select a suitable length for the piezoelectric material along its extension direction, allowing the piezoelectric material to undergo Brownian motion when placed in a fluid.

[0174] In some embodiments of any of the foregoing aspects, the spacing between the nanounits in the nanoarray is approximately 5 nm to approximately 20 μm (e.g., 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, 210 nm, 220 nm, 230 nm, 240 nm, 250 nm, 260 nm, 270 nm, 280 nm, 290 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm ... The space is available in μm or 10 μm, 20nm-5μm, 50nm-1μm, 80nm-500nm, or 100nm-300nm. The size of this space is sufficient to allow fluid to fill the space between piezoelectric micro / nanomaterials, and also sufficient to bend them to generate a piezoelectric potential.

[0175] In some embodiments of any of the foregoing aspects, the piezoelectric micro / nano unit and the additional micro / nano unit are each independently a nanorod, nanosheet, nanowire, nanoribbon, nanotube, nanohelix, or a combination thereof.

[0176] In some embodiments of any of the foregoing aspects, the piezoelectric semiconductor micro / nanomaterial is selected from hexagonal wurtzite piezoelectric materials.

[0177] In some embodiments of any of the foregoing aspects, the hexagonal wurtzite piezoelectric material is selected from ZnO, GaN, ZnS, CdS, InN, InGaN, CdTe, CdSe, ZnSnO3, and combinations thereof.

[0178] In some embodiments of any of the foregoing aspects, the perovskite piezoelectric material has the general formula ABO3; wherein A is a rare earth or alkaline earth metal ion and B is a transition metal ion.

[0179] In some embodiments of any of the foregoing aspects, the perovskite piezoelectric material is selected from lead zirconate titanate (PZT), barium titanate (BaTiO3), potassium sodium niobate (KNN), and combinations thereof.

[0180] In some embodiments of any of the foregoing aspects, the polymer piezoelectric material is selected from polyvinylidene fluoride (PVDF) and polydimethylsiloxane (PDMS).

[0181] In some embodiments of any of the foregoing aspects, the piezoelectric micro / nano unit is a ZnO nanoarray.

[0182] In some embodiments of any of the foregoing aspects, the shell material is a metallic material, and the work function of the metallic material is greater than or less than the work function of the piezoelectric semiconductor micro / nano material.

[0183] In some embodiments of any of the foregoing aspects, the shell material is another semiconductor material capable of forming a heterojunction with the piezoelectric semiconductor micro / nanomaterial.

[0184] In some embodiments of any of the foregoing aspects, the shell material is a metallic material selected from Au, Pt, Ag, Ti, Al, and combinations thereof.

[0185] In some embodiments of any of the foregoing aspects, the shell material is a semiconductor material selected from CuO, silicon wafers, Cu2O, NiO, Co3O4, and combinations thereof.

[0186] In some embodiments of any of the foregoing aspects, the shell material is formed by magnetron sputtering, electron beam evaporation, thermal deposition, or sol-gel deposition on the surface of the upper conductive layer to which the nanounits are fixed.

[0187] In some embodiments of any of the foregoing aspects, for example, the piezoelectric micro / nano unit is an n-type ZnO nanoarray, and the shell material is a semiconductor material selected from p-type CuO, p-type silicon wafer, p-type Cu2O, p-type NiO, p-type Co3O4 and combinations thereof.

[0188] On the other hand, this application provides articles, devices, or power supply devices that include the energy conversion apparatus described in this disclosure. In some embodiments, the articles or devices are powered by the energy conversion apparatus.

[0189] In addition, this application provides the use of the energy conversion device described in this disclosure in energy conversion and harvesting, such as energy storage, sensors, wearable devices, and mobile devices.

[0190] The inventions of this application provide one or more of the following advantages:

[0191] (1) The energy conversion device of the present invention can convert molecular thermal motion into electrical energy output.

[0192] (2) The energy source of the energy conversion device of the present invention is abundant and wide-ranging, and unlike some other energy sources, it does not have many usage problems. It can be integrated with the device and achieve stable external output of electrical energy.

[0193] (3) The energy conversion device of the present invention is environmentally friendly and can be widely used in power supply devices and items and equipment that require it to provide electrical energy, and has a good application prospect.

[0194] Example

[0195] The following examples are for illustrative purposes only and are not intended to limit the scope of this application.

[0196] Example 1

[0197] The following combination Figure 1 The device and its manufacturing method of the present invention are described in detail below. Figure 1 The meanings of the labels in the figures are as follows: 1. ZnO piezoelectric nanoarray, 2. Metal substrate Zn, 3. Metal film Au, 4. Liquid n-octane, 5. Encapsulation layer, 6. Lead wire.

[0198] ZnO nanosheet array growth via ethylenediamine vapor method:

[0199] A 3cm × 3cm Zn sheet was polished to a mirror finish using a metallographic polishing machine, then ultrasonicated for 10 minutes each time with ethanol, acetone, and deionized water, and finally dried with nitrogen. A specific amount of ethylenediamine solution was measured and diluted with deionized water to form a 3.75 mol / L solution. 30 mL of this solution was poured into a weighing bottle, and the Zn sheet was attached to the inside of the bottle cap. After placing the weighing bottle at room temperature for 48 hours, the Zn sheet was removed, rinsed with deionized water to remove surface deposits, and dried with nitrogen. A ZnO nanosheet array was prepared and grown along the C-axis, typically with a height of 3.5 μm, a width of ~40 nm, and a length of ~250 nm.

[0200] Growth of ZnO nanorod arrays via ethylenediamine vapor method:

[0201] A 3cm × 3cm Zn sheet was polished to a mirror finish using a metallographic polishing machine, then ultrasonicated for 10 minutes each time with ethanol, acetone, and deionized water, followed by washing and drying with nitrogen. A specific amount of ethylenediamine solution was diluted with deionized water and stirred until a 3.75 mol / L solution was formed. 30 mL of this solution was poured into a weighing bottle, and the Zn sheet was attached to the inside of the bottle cap. A mask was then placed over the weighing bottle. After incubating the weighing bottle at room temperature for 48 hours, the Zn sheet was removed, rinsed with deionized water to remove surface deposits, and dried with nitrogen. ZnO nanorod arrays were prepared and grown along the C-axis, typically with a length of ~2.5 μm and a diameter of ~60 nm.

[0202] Upper electrode preparation

[0203] On the surface of the ZnO nanosheet array, an Au film is sputtered by magnetron sputtering as the top electrode.

[0204] Add fluid

[0205] Octane (electronic grade, purity ≥99.999%) is dropped onto the surfaces with ZnO nanorod arrays and Au plating, filling both surfaces completely. A spacer is placed around the ZnO nanorod array surface, and the Au-plated surface is placed upside down on top, applying a force to ensure tight contact. The thickness of the spacer after applying the force is not less than the distance from the free end of the piezoelectric nanounit (ZnO nanorod array) to the surface of the lower conductive layer (Zn sheet) that fixes the piezoelectric nanounit, and is less than the sum of the distance from the free end of the piezoelectric nanounit to the surface of the lower conductive layer that fixes the piezoelectric nanounit and the distance from the free end of the Au-plated ZnO nanosheet array to the surface of the upper conductive layer (Zn sheet) that fixes the ZnO nanosheet array.

[0206] Packaging

[0207] Copper wire leads were used, and the entire device was quickly encapsulated with epoxy resin. After 5 hours of epoxy resin drying, the entire device was completed.

[0208] The current-voltage curve of the energy conversion device formed by the method provided in this embodiment at room temperature is shown in Figure 2, indicating that it has Schottky characteristics, with Zn sheet as positive electrode and Au as negative electrode. Figure 3 The voltage and current output of the energy conversion device at room temperature indicate that the device has good power generation characteristics and can convert the thermal motion of liquid molecules into electrical energy output.

[0209] Example 2

[0210] ZnO nanosheet array growth via ethylenediamine vapor method:

[0211] 3cm × 3cm Zn sheets were sequentially sonicated in ethanol, acetone, and deionized water for 10 min each, then washed and dried under nitrogen. A specific amount of ethylenediamine solution was diluted with deionized water and stirred until a 3.75 mol / L solution was formed. 30 mL of this solution was poured into a beaker, and the Zn sheet was suspended above it and sealed. The beaker was left at room temperature for 48 h. The Zn sheet was then removed, rinsed with deionized water to remove surface deposits, and dried under nitrogen. A ZnO nanosheet array was prepared and grown along the C-axis, typically with a height of 3.5 μm, a width of 40 nm, and a length of 250 nm.

[0212] Upper electrode preparation

[0213] On the ZnO array surface described above, an Au film is magnetron sputtered as the top electrode.

[0214] Add fluid

[0215] Dimethyl carbonate is dropped onto the surfaces with ZnO arrays and Au plating, allowing the liquid to fill both surfaces completely. After placing gaskets around the ZnO array surface, the Au-plated surface is placed upside down on top, and a certain force is applied from above to ensure tight contact.

[0216] Packaging

[0217] Copper wire leads were used, and the entire device was quickly encapsulated with epoxy resin. After 5 hours of epoxy resin drying, the entire device was completed.

[0218] Figure 4 This is the current and voltage output curve of the device in this embodiment at room temperature. Figure 5 The cyclic voltammetry curve of the device indicates that the device exhibits double-layer capacitance behavior, and its output value may be a superposition of capacitive and piezoelectric effects.

[0219] Example 3

[0220] ZnO nanosheet array growth via ethylenediamine vapor method:

[0221] 3cm × 3cm Zn sheets were sequentially sonicated in ethanol, acetone, and deionized water for 10 min each, then washed and dried under nitrogen. A specific amount of ethylenediamine solution was diluted with deionized water and stirred until a 3.75 mol / L solution was formed. 30 mL of this solution was poured into a beaker, and the Zn sheet was suspended above it and sealed. The beaker was left at room temperature for 48 h. The Zn sheet was then removed, rinsed with deionized water to remove surface deposits, and dried under nitrogen. ZnO nanosheet arrays were prepared and grown along the C-axis, typically with a height of 3.5 μm, a width of ~40 nm, and a length of ~250 nm.

[0222] Upper electrode preparation

[0223] On the ZnO array surface described above, an Au film is magnetron sputtered as the top electrode.

[0224] Packaging

[0225] After placing gaskets around the surface with the ZnO array, the Au-plated surface is placed upside down on top, and a certain force is applied from above to ensure tight contact. Copper foil leads are then attached, and the entire device is rapidly encapsulated with epoxy resin under vacuum conditions. After the epoxy resin dries for 5 hours, the entire device is complete.

[0226] Figure 6 The figures show the current and voltage output curves of the device in this embodiment at room temperature. The device in Example 3 without encapsulated fluid did not detect any effective electrical output.

[0227] Example 4

[0228] The following combination Figure 7 The device and its manufacturing method of the present invention are described in detail below. Figure 7The meanings of the labels in the figures are as follows: 1. BaTiO3 nanorod array, 2. FTO substrate, 3. Aluminum foil, 4. Liquid n-octane, 5. Encapsulation layer, 6. Lead wire.

[0229] First step: Hydrothermal synthesis of TiO2 nanoarrays

[0230] A 3cm × 3cm × 2.2mm FTO sample was placed in a 1:1:1 mixture of distilled water, acetone, and isopropanol and sonicated for 30 minutes, then rinsed with methanol and distilled water. The FTO was then placed vertically in a reaction vessel containing 10mL of distilled water, 10mL of 37% hydrochloric acid, and 1mL of titanium isopropoxide solution, and sealed. The reaction vessel was placed in an oven at 200°C for 3 hours. After the reaction was complete, the FTO was removed, cooled to room temperature, rinsed with distilled water, and dried under nitrogen.

[0231] The second step involves the hydrothermal synthesis of BaTiO3 nanoarrays.

[0232] The substrate was placed in a reactor containing Ba(OH)₂·8H₂O solution and incubated at 170°C for 8 hours. After the reaction, the substrate was removed, cooled to room temperature, rinsed with distilled water, and air-dried at room temperature. The TiO₂ nanoarray grown on FTO was converted into a BaTiO₃ nanoarray, which was then placed at 600°C for 30 minutes to reduce defects. The grown BaTiO₃ nanorods were ~1 μm long and ~90 nm in diameter.

[0233] Device polarization

[0234] An aluminum foil was placed over an FTO substrate with a BaTiO3 nanorod array as the upper electrode, and the conductive surface of the FTO substrate was used as the lower electrode, with copper foil leads attached. A DC voltage of 120 kV / cm was applied between the two electrodes, and the substrate was left to stand for 24 hours.

[0235] Device packaging

[0236] Add n-octane between the upper and lower electrodes to fill the entire upper and lower surfaces, and then encapsulate the entire device with epoxy resin.

[0237] Example 5

[0238] Molecular thermal motion serves as the energy source for thermal dynamometers, and its kinetic energy is directly proportional to absolute temperature. Theoretically, the higher the temperature, the more intense the thermal motion of fluids such as n-octane molecules, which in turn drives the Brownian motion of ZnO nanoarrays, resulting in greater deformation.

[0239] The following combination Figure 1 The output performance of the device was tested under different temperature conditions.

[0240] Temperature control in the experiment

[0241] The experimental temperature conditions were obtained using a water bath method, with a temperature sensor placed inside the insulation system to monitor the temperature in real time. Three temperature points were selected for the experiment, from lowest to highest: -13.3°C, -0.4°C, and 9.8°C. The -13.3°C temperature was achieved using an ice-salt bath, while the other temperatures were achieved by mixing ice with cold / hot water. The insulation effect of the system was monitored for one hour, and the temperature variations at different temperatures were all less than 2°C, considered within an acceptable range.

[0242] Output performance testing at different temperatures

[0243] The same encapsulated device (prepared according to the preparation method described in Example 1) was placed sequentially in a heat preservation system with temperatures ranging from low to high. After standing for 10 minutes, its current and voltage output were tested.

[0244] Figure 8 The voltage and current output of this energy conversion device at different temperatures. Figure 8 In the figure, 'a', 'b', and 'c' correspond to the output performance of the energy conversion device at the aforementioned temperatures of -13.3°C, -0.4°C, and 9.8°C, respectively. As assumed, the generator's output current and voltage increase with increasing temperature. The current and voltage outputs satisfy the linear superposition condition, eliminating other interferences caused by the test system. The experimental results further verify that the output of the thermal motion generator is indeed related to molecular thermal motion.

[0245] The present invention has been described in detail above with general descriptions and specific embodiments. However, modifications or improvements can be made to the present invention, and arbitrary combinations can be made as needed, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. An energy conversion device, comprising: Upper conductive layer; Lower conductive layer; It is disposed below the upper conductive layer; At least one piezoelectric micro / nano unit and fluid are disposed between the upper conductive layer and the lower conductive layer; The piezoelectric micro / nano units have piezoelectric properties and are immersed in the fluid; The fluid in question is a liquid. The energy conversion device further includes at least one additional micro / nano unit. One end of the piezoelectric micro / nano unit is fixed to the surface of the lower conductive layer facing the upper conductive layer, and one end of the additional micro / nano unit is fixed to the surface of the upper conductive layer facing the lower conductive layer. The other end of the piezoelectric micro / nano unit is a free end, so that the piezoelectric micro / nano unit comes into contact with the additional micro / nano unit when it randomly vibrates and deforms due to the molecular thermal work of the fluid. The additional micro / nano units satisfy at least one of the following (i) and (ii): (i) The additional micro / nano unit comprises a material capable of forming a Schottky junction or heterojunction with the piezoelectric micro / nano unit or is composed of a material capable of forming a Schottky junction or heterojunction with the piezoelectric micro / nano unit; (ii) The surface of the additional micro / nano unit is coated with a shell material; the shell material is a material capable of forming a Schottky junction or heterojunction with the piezoelectric micro / nano unit. The energy conversion device further includes an encapsulation layer; the encapsulation layer is disposed on the outer periphery of the energy conversion device, and The piezoelectric micro / nano unit and the additional micro / nano unit are each at least partially or completely immersed in the fluid.

2. The energy conversion device as described in claim 1, wherein: One end of the piezoelectric micro / nano unit is fixed to the surface of the lower conductive layer facing the upper conductive layer, and the other end is in contact with the upper conductive layer.

3. The energy conversion device as described in claim 2, wherein: The upper conductive layer covers the surface of the lower conductive layer on which the piezoelectric micro / nano units are fixed.

4. The energy conversion device as described in claim 1, wherein: The other end of the additional micro / nano unit is a free end. The piezoelectric micro / nano units on the surface of the lower conductive layer form a cross with the additional micro / nano units on the surface of the upper conductive layer.

5. The energy conversion device as described in claim 1, wherein: The micro / nano materials in the additional micro / nano units may be the same as or different from the piezoelectric micro / nano materials in the piezoelectric micro / nano units; When the micro / nano material in the additional micro / nano unit is the same as the piezoelectric micro / nano material in the piezoelectric micro / nano unit, the shell material is wrapped on the surface of the additional micro / nano unit.

6. The energy conversion device as claimed in claim 1, wherein: The additional micro / nano units are non-piezoelectric micro / nano units.

7. The energy conversion device as claimed in claim 1, wherein the at least one piezoelectric micro / nano unit is two or more piezoelectric micro / nano units, one end of each piezoelectric micro / nano unit is fixed on each of the two opposing surfaces of the upper conductive layer and the lower conductive layer, and the other end of each piezoelectric micro / nano unit on at least one of the upper and lower conductive layers is a free end, such that when the piezoelectric micro / nano unit with the free end on the at least one conductive layer vibrates randomly, it can contact the piezoelectric micro / nano unit on the opposite conductive layer; in, The surface of the piezoelectric micro / nano unit on the surface of the upper conductive layer or the surface of the piezoelectric micro / nano unit on the surface of the lower conductive layer is covered with a shell material; the shell material is a material that can form a Schottky junction or a heterojunction with the piezoelectric micro / nano unit.

8. The energy conversion device as described in claim 7, wherein: The piezoelectric micro / nano units on the surface of the upper conductive layer and the piezoelectric micro / nano units on the surface of the lower conductive layer form a cross.

9. The energy conversion device according to any one of claims 1 to 8, wherein: The two surfaces of the upper conductive layer and the lower conductive layer that are opposite to each other are substantially parallel.

10. The energy conversion device according to any one of claims 1 to 8, wherein: The piezoelectric micro / nano units and / or the additional micro / nano units are micro / nano arrays each time they appear.

11. The energy conversion device according to any one of claims 1 to 8, wherein: The fluid at least partially or completely fills the space between the two opposing surfaces of the upper conductive layer and the lower conductive layer.

12. The energy conversion device according to any one of claims 1 to 8, wherein: The fixing is performed along the orientation of the surface perpendicular to the lower conductive layer or the surface of the upper conductive layer.

13. The energy conversion device according to any one of claims 1 to 8, wherein: The encapsulation layer contains an adhesive.

14. The energy conversion device as claimed in claim 13, wherein: The adhesive is selected from one or more of epoxy resin, silicone, and EVA.

15. The energy conversion device according to any one of claims 1 to 8, wherein: The energy conversion device further includes leads; the leads are led out from the upper conductive layer and the lower conductive layer respectively.

16. The energy conversion device according to any one of claims 1 to 8, wherein: The fluid is a heated liquid.

17. The energy conversion device according to any one of claims 1 to 8, wherein: The dielectric constant of the liquid is less than 80.

18. The energy conversion device according to any one of claims 1 to 8, wherein: The dielectric constant of the liquid is less than 40.

19. The energy conversion device according to any one of claims 1 to 8, wherein: The dielectric constant of the liquid is less than 10.

20. The energy conversion device according to any one of claims 1 to 8, wherein: The dielectric constant of the liquid is less than 4.

0.

21. The energy conversion device according to any one of claims 1 to 8, wherein: The dielectric constant of the liquid is less than 3.

0.

22. The energy conversion device according to any one of claims 1 to 8, wherein: The dielectric constant of the liquid is less than 2.

5.

23. The energy conversion device according to any one of claims 1 to 8, wherein: The dielectric constant of the liquid is less than 2.

0.

24. The energy conversion device according to any one of claims 1 to 8, wherein: The viscosity of the liquid is less than 80,000 mPa·s.

25. The energy conversion device according to any one of claims 1 to 8, wherein: The viscosity of the liquid is less than 8000 mPa·s.

26. The energy conversion device according to any one of claims 1 to 8, wherein: The viscosity of the liquid is less than 800 mPa·s.

27. The energy conversion device according to any one of claims 1 to 8, wherein: The viscosity of the liquid is less than 80 mPa·s.

28. The energy conversion device according to any one of claims 1 to 8, wherein: The viscosity of the liquid is less than 8 mPa·s.

29. The energy conversion device according to any one of claims 1 to 8, wherein: The viscosity of the liquid is less than 0.8 mPa·s.

30. The energy conversion device according to any one of claims 1 to 8, wherein: The liquid is a nonpolar or weakly polar liquid.

31. The energy conversion device according to any one of claims 1 to 8, wherein: The liquid is selected from one or more of dimethyl carbonate, diethyl carbonate, tetrachloroethylene, cyclopentene, n-octane, n-hexane, ethanol, and dichloroethane.

32. The energy conversion device according to any one of claims 1 to 8, wherein: The upper conductive layer and the lower conductive layer each independently comprise one or more of the following materials: metals, carbon materials, and semiconductor materials.

33. The energy conversion device according to any one of claims 1 to 8, wherein: The upper conductive layer and the lower conductive layer each independently comprise one or more of the following materials: Au, Pt, Ag, Cu, Zn, ITO, FTO, or C.

34. The energy conversion device according to any one of claims 1 to 8, wherein: The upper conductive layer and the lower conductive layer are each independently a sheet-like or nanostructure covered with a conductive film.

35. The energy conversion device as claimed in claim 34, wherein: The nanostructure is a nanogroove and / or a nanoarray.

36. The energy conversion device according to any one of claims 1 to 8, wherein the minimum radial dimension of at least a portion of the cross-section of each nanounit along its extension direction is 1 nm to 10 μm.

37. The energy conversion device according to any one of claims 1 to 8, wherein the minimum radial dimension of at least a portion of the cross-section of each nanounit along its extension direction is 10 nm to 1 μm.

38. The energy conversion device according to any one of claims 1 to 8, wherein the minimum radial dimension of at least a portion of the cross-section of each nanounit along its extension direction is 20 nm to 300 nm.

39. The energy conversion device according to any one of claims 1 to 8, wherein the minimum radial dimension of at least a portion of the cross-section of each nanounit along its extension direction is 10 nm to 500 nm.

40. The energy conversion device according to any one of claims 1 to 8, wherein the minimum radial dimension of at least a portion of the cross-section of each nanounit along its extension direction is 10 nm to 100 nm.

41. The energy conversion device according to any one of claims 1 to 8, wherein the piezoelectric micro / nano unit and the additional micro / nano unit are both nanoarrays, and the gap between the nanounits in the nanoarray is 5 nm to 20 μm.

42. The energy conversion device according to any one of claims 1 to 8, wherein the piezoelectric micro / nano unit and the additional micro / nano unit are both nanoarrays, and the gap between the nanounits in the nanoarray is 20 nm to 5 μm.

43. The energy conversion device according to any one of claims 1 to 8, wherein the piezoelectric micro / nano unit and the additional micro / nano unit are both nanoarrays, and the gap between the nanounits in the nanoarray is 50 nm-1 μm.

44. The energy conversion device according to any one of claims 1 to 8, wherein the piezoelectric micro / nano unit and the additional micro / nano unit are both nanoarrays, and the gap between the nanounits in the nanoarray is 80nm-500nm.

45. The energy conversion device according to any one of claims 1 to 8, wherein the piezoelectric micro / nano unit and the additional micro / nano unit are both nanoarrays, and the gap between the nanounits in the nanoarray is 100nm-300nm.

46. ​​The energy conversion device according to any one of claims 1 to 8, wherein: The piezoelectric micro / nano units and / or the additional micro / nano units are each independently one or a combination of two or more of the following: nanorods, nanosheets, nanowires, nanoribbons, nanotubes, or nanohelices.

47. The energy conversion device according to any one of claims 1 to 8, wherein: The piezoelectric micro / nano unit comprises or is composed of piezoelectric semiconductor micro / nano materials.

48. The energy conversion device as claimed in claim 47, wherein: The piezoelectric semiconductor micro / nanomaterials are selected from hexagonal wurtzite piezoelectric materials.

49. The energy conversion device according to any one of claims 1 to 8, wherein: The piezoelectric micro / nano unit comprises piezoelectric micro / nano materials selected from one or more combinations of hexagonal wurtzite piezoelectric materials, perovskite piezoelectric materials, or polymer piezoelectric materials, or is composed of the piezoelectric micro / nano materials.

50. The apparatus of claim 49, wherein: The hexagonal wurtzite piezoelectric material is selected from one or more combinations of ZnO, GaN, ZnS, CdS, InN, InGaN, CdTe, CdSe or ZnSnO3.

51. The energy conversion device as claimed in claim 49, wherein: The general formula of the perovskite piezoelectric material is ABO3; where A is a rare earth or alkaline earth metal ion and B is a transition metal ion.

52. The energy conversion device as claimed in claim 49, wherein: The perovskite piezoelectric material is selected from one or more combinations of lead zirconate titanate (PZT), barium titanate (BaTiO3), or potassium sodium niobate (KNN).

53. The energy conversion device as described in claim 49, wherein: The polymer piezoelectric material is selected from polyvinylidene fluoride (PVDF) and / or polydimethylsiloxane (PDMS).

54. The energy conversion device according to any one of claims 1 to 8, wherein: The piezoelectric micro / nano units are ZnO nanoarrays.

55. The energy conversion device as claimed in claim 47, wherein: The shell material is a metallic material, and the work function value of the metallic material is greater than or less than the work function value of the piezoelectric semiconductor micro / nano material.

56. The energy conversion device as claimed in claim 55, wherein: The shell material is a metal or alloy material selected from one or more combinations of Au, Pt, Ag, Ti, Al or C.

57. The energy conversion device according to any one of claims 1 to 8, wherein: The shell material is selected from one or more combinations of CuO, silicon wafer, Cu2O, NiO or Co3O4.

58. The energy conversion device according to any one of claims 1 to 8, wherein: The shell material is formed by magnetron sputtering, electron beam evaporation, thermal deposition, or sol-gel method on the surface of the upper conductive layer on which the additional micro / nano units or the piezoelectric micro / nano units are fixed.

59. A method of manufacturing an energy conversion device as described in any one of claims 1 to 58, comprising: Provide an upper conductive layer; A lower conductive layer is provided and disposed below the upper conductive layer; At least one piezoelectric micro / nano unit and a fluid are disposed between the upper conductive layer and the lower conductive layer; The piezoelectric micro / nano units are immersed in the fluid. The fluid in question is a liquid. The energy conversion device further includes additional micro / nano units, wherein the additional micro / nano units satisfy at least one of the following (i) and (ii): (i) The additional micro / nano unit comprises a material capable of forming a Schottky junction or heterojunction with the piezoelectric micro / nano unit or is composed of a material capable of forming a Schottky junction or heterojunction with the piezoelectric micro / nano unit; (ii) The surface of the additional micro / nano units is covered with a shell material; The shell material is a material capable of forming a Schottky junction or heterojunction with the piezoelectric micro / nano unit; The method further includes: Fixing steps: Fix one end of the piezoelectric micro / nano unit to the surface of the lower conductive layer, and fix one end of the additional micro / nano unit to the surface of the upper conductive layer, with the other end of the piezoelectric micro / nano unit being a free end; Assembly steps: The piezoelectric micro / nano units fixed on the lower conductive layer are assembled with the additional micro / nano units fixed on the upper conductive layer facing each other, such that the piezoelectric micro / nano units come into contact with the additional micro / nano units when they randomly vibrate and deform due to the molecular thermal work of the fluid; wherein, when the additional micro / nano units do not satisfy the above (i), the upper conductive layer on which the additional micro / nano units are fixed is the upper conductive layer on which the additional micro / nano units are fixed and encased by the shell material; Fluid introduction steps; and Device encapsulation step: to provide the encapsulation layer on the outer periphery of the energy conversion device.

60. The method of claim 59, wherein: The fixing step includes growing the piezoelectric micro / nano units on the surface of the lower conductive layer.

61. The method of claim 60, wherein: The other end of the additional micro / nano unit is a free end; the fixing step includes growing the additional micro / nano unit and the piezoelectric micro / nano unit on the surface of the upper conductive layer and the surface of the lower conductive layer, respectively.

62. The method of claim 61, wherein: The growth is oriented perpendicular to the surface of the upper conductive layer or the surface of the lower conductive layer.

63. The method of claim 59, wherein: The assembly step includes: contacting the other end of the fixed piezoelectric micro / nano unit with the upper conductive layer.

64. The method of claim 63, wherein: The fixing step includes growing the piezoelectric micro / nano units on the surface of the lower conductive layer, and the assembly step includes covering the upper conductive layer onto the surface of the lower conductive layer on which the piezoelectric micro / nano units are grown.

65. The method of claim 59, wherein: The fluid introduction step includes introducing the fluid before, after, or during the assembly step.

66. The method of claim 65, wherein: The fluid introduction step includes introducing the fluid to the surface of the lower conductive layer where the piezoelectric micro / nano units are fixed before the assembly step, or introducing the fluid to the surface of the lower conductive layer where the piezoelectric micro / nano units are fixed and the surface of the upper conductive layer where the additional micro / nano units are fixed before the assembly step.

67. The method of claim 65, wherein: The fluid introduction step includes introducing the fluid between the upper conductive layer and the lower conductive layer after the assembly step.

68. The method of claim 59, wherein: The device packaging steps include physical packaging or chemical packaging.

69. The method of claim 68, wherein: The encapsulation is either mechanical or encapsulated using adhesives or tape.

70. The method of claim 59, wherein: The piezoelectric micro / nano unit comprises piezoelectric micro / nano materials selected from hexagonal wurtzite piezoelectric materials, perovskite piezoelectric materials, polymer piezoelectric materials, and combinations thereof, or the piezoelectric micro / nano unit is composed of piezoelectric micro / nano materials selected from hexagonal wurtzite piezoelectric materials, perovskite piezoelectric materials, polymer piezoelectric materials, and combinations thereof; when the piezoelectric micro / nano unit comprises piezoelectric micro / nano materials selected from perovskite piezoelectric materials, polymer piezoelectric materials, and combinations thereof, the energy conversion device is polarized before the fluid introduction step.

71. The method of claim 70, wherein: The polarization involves applying an electric field between the upper conductive layer and the lower conductive layer, causing the layer to spontaneously polarize and preferentially align along the direction of the electric field under the influence of the electric field.

72. The method of claim 59, wherein: The method further includes a wrapping step: when the additional micro / nano unit does not meet the above (i), the shell material is wrapped on the surface of the additional micro / nano unit; wherein the shell material is a material that can form a Schottky junction or a heterojunction with the piezoelectric micro / nano unit.

73. The method of claim 59, wherein: The assembly step includes: placing a pad around the surface of the lower conductive layer on which the piezoelectric micro / nano units are fixed, wherein the thickness of the pad, or the thickness of the pad after compression when the pad is compressed under force, is not less than the distance from the free end of the piezoelectric micro / nano unit to the surface of the lower conductive layer on which the piezoelectric micro / nano unit is fixed, and is less than the sum of the distance from the free end of the piezoelectric micro / nano unit to the surface of the lower conductive layer on which the piezoelectric micro / nano unit is fixed and the distance from the free end of the additional micro / nano unit to the surface of the upper conductive layer on which the additional micro / nano unit is fixed; and placing the upper conductive layer on which the additional micro / nano unit is fixed on the pad, such that the additional micro / nano units on the surface of the upper conductive layer and the piezoelectric micro / nano units on the surface of the lower conductive layer form an interlocking arrangement during the assembly.

74. The method of claim 73, wherein: The fluid introduction step includes introducing the fluid, which is a liquid, into the space surrounded by the entire pad after the pad is placed on it, and then placing the upper conductive layer on which the additional micro / nano units are fixed on the pad, thereby introducing the fluid during the assembly process; wherein when the additional micro / nano units do not satisfy the above (i), the surface of the upper conductive layer on which the additional micro / nano units are fixed is the surface of the upper conductive layer on which the additional micro / nano units are fixed and wrapped by the shell material.

75. An article comprising the energy conversion apparatus according to any one of claims 1 to 58.

76. The article as claimed in claim 75, wherein: The item is powered by the energy conversion device.

77. An apparatus comprising the energy conversion device according to any one of claims 1 to 58.

78. The apparatus of claim 77, wherein: The device is powered by the energy conversion unit.

79. A power supply device comprising the energy conversion device according to any one of claims 1 to 58.

80. The energy conversion device as described in any one of claims 1 to 58 is used for energy storage.

81. The use of the energy conversion device as described in any one of claims 1 to 58 in a sensor.

82. Use of the energy conversion device as described in any one of claims 1 to 58 in a wearable device.

83. Use of the energy conversion device as described in any one of claims 1 to 58 in a mobile device.

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