CN104465119B - Based on three-dimensional ZnO@MnO2Ultracapacitor of composite Nano array interdigital electrode and preparation method thereof - Google Patents

Abstract

The invention relates to a supercapacitor based on a three-dimensional ZnO@ _MnO2 composite nano-array interdigitated electrode and a preparation method thereof. The supercapacitor includes a packaging bag and a solid electrolyte, and also includes a ZnO@MnO ₂ composite nano-array interdigital electrode, the solid electrolyte and the ZnO@MnO ₂ composite nano-array interdigital electrode are placed in the packaging bag, and the The solid electrolyte is applied on the ZnO@MnO ₂ composite nano-array interdigitated electrodes. The ZnO@MnO ₂ composite nano-array interdigitated electrode uses micro-nano processing technology to prepare a transparent interdigitated collector on a flexible transparent PET substrate, grows a three-dimensional ZnO rod nano-array on the collector by a solution method, and uses electrodeposition The process is prepared by coating a layer of MnO ₂ around the three-dimensional ZnO nanorods. The supercapacitor greatly improves the area specific capacitance of the device, and the nano-array gap provides a channel for ion transmission and exchange, and also improves the rate characteristics and cycle performance of the capacitance.

Description

Supercapacitor based on three-dimensional ZnO@MnO2 composite nanoarray interdigitated electrodes and its Preparation

technical field

The invention relates to the technical field of energy storage, in particular to a supercapacitor based on three-dimensional ZnO@ _MnO2 composite nano-array interdigitated electrodes and a preparation method thereof.

Background technique

With the continuous development of wearable and portable multimedia electronic devices, higher requirements are placed on flexible and transparent electronic devices. For example, in order to realize the commercialization of flexible display devices with ultra-thin screens, their power supply components also need to be flexible. and transparency. Commonly used devices that provide energy storage are mainly lithium batteries and supercapacitors. As a new type of electrical energy storage device, supercapacitors are widely used due to their higher energy density than traditional parallel plate capacitors, higher power density and longer life than lithium-ion batteries. Research.

Supercapacitors are mainly divided into two categories, one is called electric double layer capacitors, and the other is called Faraday capacitors or pseudocapacitors. Electric double layer capacitors are mainly composed of various carbon materials, such as carbon nanotubes, graphene, carbon fibers, and carbon black. The electrode active materials of Faraday capacitors are mainly composed of various transition metal oxides such as RuO, NiO, CO ₃ O ₄ , MnO ₂ and conductive polymers. Compared with electric double layer capacitors, the energy storage mechanism of Faraday capacitors is that the electrode materials will undergo rapid and reversible chemical reactions in the process of charging and discharging, so they will have higher specific capacity. Therefore, for high-power and high-energy super Research on capacitors is mainly focused on Faraday capacitors.

The three-dimensional nanoelectrode structure (3D) has a high specific surface area and three-dimensional ion entry and exit channels. The application of this special structure to the electrodes of high-performance supercapacitors has been proved to have broad prospects. ZnO nanorod arrays have a three-dimensional structure and are used as electrode preparation templates for 3D supercapacitors, which have shown potential advantages (Yong Zhao, Peng Jiang. MnO ₂ nanosheets grown on the ZnO-nanorod-modified carbon fiber paper for supercapacitor electrode materials, Colloids and SurfacesA: Physicochem. Eng. Aspects, 2014, 444, 232-239; Yong Zhao, Peng Jiang, SishenXie. Template-mediated synthesis of three-dimensional coral-like MnO ₂ nanostructure for supercapacitors, Journal of Power Sources, 2013, 239, 39, 39) However, there are no related reports and technologies on the use of ZnO arrays for 3D flexible transparent supercapacitor devices.

Lift-Off micro-device processing technology is a mature, simple and easy micro-device processing method. This technology processes photoresist patterns on the substrate through ultraviolet lithography technology, then deposits the required materials, and then uses acetone or Other solvents remove the photoresist, resulting in a pattern of deposited material. Using this technology to prepare interdigitated electrodes on a flexible transparent substrate is a very effective way to process transparent electronic devices. For example, patent document CN 201210579735.5 discloses a transparent and flexible electrochemical device based on a planar comb-shaped electrode structure and its The preparation method uses an interdigitated electrode to prepare an electric double layer transparent supercapacitor with a one-dimensional carbon film material as an electrode. However, the specific capacitance of the capacitor is very low, and it uses a liquid electrolyte, which has poor safety, is not easy to package, and is difficult to apply Solid-state electronic devices are difficult to meet the development requirements of high-power, high-energy flexible transparent supercapacitors.

Contents of the invention

The purpose of the present invention is to propose a supercapacitor based on three-dimensional ZnO@ _MnO2 composite nano-array interdigitated electrodes and its preparation method. The supercapacitor has strong flexibility, high transparency, high area specific capacitance and power, and cycle performance Excellent, long life, able to meet the needs of high-power charging and discharging.

For reaching this purpose, the present invention adopts following technical scheme:

On the one hand, the present invention provides a supercapacitor based on a three-dimensional ZnO@ _MnO2 composite nano-array interdigitated electrode, including a packaging bag and a solid electrolyte, and also includes a ZnO@ _MnO2 composite nano-array interdigitated electrode, the solid electrolyte and The ZnO@MnO ₂ composite nano-array interdigitated electrode is placed in the packaging bag, and the solid electrolyte is coated on the ZnO@MnO ₂ composite nano-array interdigitated electrode.

The ZnO@ _MnO2 composite nano-array interdigitated electrode is composed of a flexible transparent substrate and a three-dimensional ZnO nanorod array and _MnO2 materials located on the flexible transparent substrate, and the length of the nanorods in the three-dimensional ZnO nanorod array is 6-8 microns, the MnO ₂ material is coated on the outside of the three-dimensional ZnO nanorod array.

The flexible transparent substrate is PET, PMMA or PDMS, preferably PET, and other flexible and transparent polymer materials can be used.

The effective electrode width and electrode spacing of the ZnO@ _MnO2 composite nano-array interdigitated electrodes are 2-100 microns, such as 5 microns, 10 microns, 20 microns, 30 microns, 40 microns, 50 microns, 60 microns, 70 microns, 80 microns or 90 microns.

In another aspect, the present invention provides a method for preparing a supercapacitor as described above, comprising the following steps:

1) Preparation of solid electrolyte;

2) Spread the solid electrolyte evenly on the ZnO@MnO ₂ composite nano-array interdigitated electrodes;

3) Encapsulate the ZnO@MnO ₂ composite nano-array interdigitated electrodes coated with solid electrolyte to obtain the supercapacitor.

Step 1) The preparation of the solid electrolyte includes dissolving lithium chloride and PVA in an appropriate amount of deionized water at a mass ratio of 2:1, and stirring in a water bath at 85°C-90°C for 1 hour to obtain a solid electrolyte.

Step 3) The material of the packaging bag is PMMA.

The present invention also provides a preparation method of the ZnO@MnO ₂ composite nano-array interdigitated electrode: using micro-nano processing technology, an interdigital collector is prepared on a flexible transparent substrate, and a three-dimensional electrode is grown on the interdigital collector by a solution method. ZnO nanorod arrays, and a layer of MnO ₂ active material was coated around the three-dimensional ZnO nanorods by electrodeposition process to prepare 3D flexible and transparent ZnO@MnO ₂ composite nanoarray interdigitated electrodes.

The preparation method of the ZnO@ _MnO2 composite nano-array interdigitated electrode specifically includes the following steps:

1) Select the substrate: select a flexible transparent substrate and perform surface treatment on it;

2) Design the interdigitated electrode pattern: design the pattern of the mask plate, and process the interdigitated electrode pattern on the substrate by using the semiconductor device micromachining process;

3) Preparation of collector electrode and ZnO seed layer: depositing Pt thin film and ZnO thin film on the interdigitated electrode pattern of the substrate;

4) Preparation of three-dimensional ZnO nanorod array interdigitated electrodes: place the substrate in step 3) in a sealable container, add a three-dimensional ZnO nanorod array precursor solution, fully stir and seal, and then heat in a water bath to obtain Three-dimensional ZnO nanorod array interdigitated electrodes;

5) Depositing MnO ₂ : coating the three-dimensional ZnO nanorod array obtained in step 4) with MnO ₂ to obtain a three-dimensional ZnO nanorod array interdigitated electrode coated with MnO ₂ ;

6) Lift-Off process: the excess photoresist in the MnO ₂ -coated three-dimensional ZnO nanorod array interdigital electrodes is removed to obtain a flexible and transparent ZnO@MnO ₂ composite nanoarray interdigital electrodes.

Step 1) The material of the flexible transparent substrate is PET, PMMA or PDMS, preferably PET, and other flexible transparent polymer materials are equally applicable; the instrument used for the surface treatment is an oxygen plasma surface treatment machine, and the time of the treatment For 2-3 minutes, the substrate material is surface treated to remove organic impurities and facilitate the adhesion between the photoresist and the substrate in the later stage.

Step 2) The ultraviolet lithography technology is used for making the pattern of the interdigitated electrodes, and the specific operating conditions are: select the photoresist model AZ4620, the thickness of the glue is 3-4 microns, and the speed of the glue is 1000-2000 rpm, The pre-baking temperature is 80-105°C, the exposure time is 15-25s, and the developing time is 65-70s.

The designed effective electrode width and electrode spacing of the interdigitated electrodes can be selected within 2-100 microns according to the light transmittance requirement, preferably the electrode width is 100 microns, and the electrode spacing is also 100 microns.

Step 3) the Pt thin film and ZnO thin film are deposited by magnetron sputtering, the thickness of the Pt thin film is 60-70nm, such as 62nm, 64nm, 65nm, 66nm, 67nm, 68nm or 69nm, the thickness of the ZnO thin film 10-20nm, such as 11nm, 12nm, 14nm, 15nm, 16nm, 17nm, 18nm or 19nm.

Step 4) The precursor solution of the three-dimensional ZnO nanorod array is 0.5-0.55mol/L zinc nitrate solution, 0.1-0.15mol/L polyvinyl imine solution, 0.25-0.3mol/L hexamethylenetetrafluoroethylene Amine solution, mass fraction are the mixed solution of 75% ammoniacal liquor and deionized water; Described deionized water: zinc nitrate solution: polyvinylimine solution: hexamethylenetetramine solution: the volume ratio of ammoniacal liquor is 32: 2:4:2:1; the heating temperature of the water bath is 65-70°C, such as 66°C, 67°C, 68°C or 68°C, and the heating time of the water bath is 5-13h, such as 6h, 7h, 8h , 9h, 10h, 11h or 12h. The concentration of the zinc nitrate solution is 0.5-0.55mol/L, such as 0.51mol/L, 0.52mol/L, 0.53mol/L or 0.54mol/L, and the concentration of the polyvinylimine solution is 0.1-0.15 mol/L, such as 0.11mol/L, 0.12mol/L, 0.13mol/L or 0.14mol/L, the concentration of the hexamethylenetetramine solution is 0.25-0.3mol/L, such as 0.26mol/L, 0.27mol/L, 0.28mol/L or 0.29mol/L.

Step 4) The three-dimensional ZnO nanorod array is also coated with a 10-15nm Pt thin film such as 11nm, 12nm, 13nm or 14nm by magnetron sputtering technology.

Step 5) The deposited MnO ₂ can be prepared by physical deposition such as magnetron sputtering, electron beam evaporation or electrochemical deposition, and other active materials such as RuO ₂ , NiO or CO can also be deposited on the three-dimensional ZnO nanorod array ₃ O ₄ . The present invention adopts three-electrode electrochemical deposition, and the operating conditions of the three-electrode electrochemical deposition are: the three-dimensional ZnO nanorod array interdigitated electrode is used as the working electrode, the mixed solution of manganese nitrate and sodium nitrate is used as the electrodeposition solution, and the platinum sheet is used as the counter electrode. Electrode, calomel electrode is the reference electrode, the current density of electrodeposition is 0.5-0.6mA/cm ² , such as 0.51mA/cm ² , 0.52mA/cm ² , 0.54mA/cm ² , 0.55mA/cm ² , 0.57 mA/cm ² or 0.59mA/cm ² , the electrodeposition time is 25-30min, such as 26min, 27min, 28min or 29min, and MnO ₂ is electrodeposited around the interdigitated electrodes of the three-dimensional ZnO nanorod array.

Compared with prior art, the beneficial effect of the present invention is:

(1) The solid-state supercapacitor device provided by the present invention has strong flexibility and high transparency;

(2) The solid-state supercapacitor provided by the present invention has higher area specific capacitance and power, excellent cycle performance and long life;

(3) The solid-state supercapacitor provided by the present invention can meet the high-power charge and discharge requirements, can be applied to the display field and the field of wearable electronic products, and meets people's needs for modern technology products and high-quality green life.

Description of drawings

FIG. 1 is a schematic diagram of the design of an interdigitated electrode mask provided in Embodiment 1 of the present invention.

Fig. 2 is a SEM image of the three-dimensional ZnO nanorod array interdigitated electrodes provided in Embodiment 1 of the present invention.

FIG. 3 is a SEM image of the ZnO@MnO ₂ composite nano-array interdigitated electrode provided in Embodiment 1 of the present invention.

Fig. 4 is a flexible transparent solid-state 3D supercapacitor provided by Embodiment 2 of the present invention.

Fig. 5 is the cyclic voltammetry curve of the flexible transparent solid-state 3D supercapacitor provided by Embodiment 2 of the present invention.

Fig. 6 is a cycle stability test curve of the flexible transparent solid-state 3D supercapacitor provided by Embodiment 2 of the present invention.

detailed description

The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and through specific implementation methods.

Example 1

Fabrication of ZnO@MnO ₂ Composite Nanoarray Interdigital Electrodes

1. Substrate selection: choose PET as the substrate, and treat it with an oxygen plasma surface treatment machine for 2 minutes.

2. Design of interdigitated electrodes: use semiconductor device micro-processing technology to process interdigitated electrode patterns on PET substrates. The pattern design of the interdigitated electrodes used as a UV lithography mask is shown in Figure 1. It can be seen from the figure that the number of pairs of prepared interdigital electrodes is 8 pairs, and the spacing and finger width between the interdigital electrodes are 100 microns. The operating conditions of the photolithography process are: the photoresist model used for ultraviolet lithography is AZ4620, the coating thickness is 3 microns, the coating speed is 2000 rpm, the pre-baking temperature is 105 degrees, the exposure time is 25s, and the developing time For 70s, an interdigitated electrode pattern was prepared on the PET sink bottom.

3. Preparation of collector electrode and ZnO seed layer: A 70nm Pt thin film and a 20nm ZnO thin film were deposited on the PET substrate with interdigitated electrode patterns prepared in the second step above by means of magnetron sputtering.

4. Preparation of ZnO nanorod array: Put the PET substrate prepared in the above step 3 into a sealable container, and add deionized water and 0.5mol/L of Zinc nitrate solution, 0.1mol/L polyvinylimine solution, 0.25mol/L hexamethylenetetramine solution and 75% ammonia water in mass fraction. After fully stirring, seal it, and then heat it in a water bath at 65° C. for 10 hours to obtain a nano-zinc oxide array of about 6 microns, as shown in FIG. 2 . It can be seen from Figure 2 that the ZnO nanorods are evenly distributed on the interdigitated Pt electrode film, the ZnO nanorods are closely arranged, and the length is about 6 microns. In order to further improve the conductivity of zinc oxide nanorods, a 10nm Pt film can be coated on the zinc oxide nanorods by magnetron sputtering;

5. Preparation of three-dimensional MnO ₂ array: The three-dimensional ZnO nanorod array is coated with cheap and environmentally friendly MnO ₂ material by three-electrode electrochemical deposition. The operating conditions of the electrochemical deposition are: the electrodeposition solution is 0.02mol/L The mixed solution of manganese nitrate and 0.1mol/L sodium nitrate, with the three-dimensional ZnO nanorod array interdigitated electrode prepared in step 4 as the working electrode, the platinum sheet as the counter electrode, and the calomel electrode as the reference electrode, the current density of electrodeposition 0.5mA/cm ² , the deposition time is 25min, electrodeposit and coat MnO ₂ electrode material around the ZnO nanorods, and obtain MnO ₂ coated ZnO nanorod arrays;

6. Lift-Off process. The three-dimensional MnO ₂ array obtained in step 5 was soaked in acetone for 2 h, and ultrasonicated for 10 min to remove excess photoresist to obtain a flexible and transparent ZnO@MnO ₂ composite nano-array interdigitated electrode, as shown in Figure 3. It can be seen from the figure that the MnO ₂ film is uniformly coated on the three-dimensional ZnO nanorod array, and the thickness of the MnO ₂ film is about 40 nm.

Example 2

Fabrication of flexible transparent solid-state 3D supercapacitors

Dissolve lithium chloride and PVA in an appropriate amount of deionized water at a mass ratio of 2:1, and stir in a water bath at 85°C for 1 hour to obtain a solid electrolyte. Spread the solid electrolyte evenly on the prepared interdigitated capacitor, and encapsulate it with PMMA to obtain a flexible transparent solid supercapacitor, as shown in Figure 4. It can be seen from the figure that the length of the solid supercapacitor is about 5cm , high transparency, can be bent, has good flexibility. The cyclic voltammetry curve of the prepared flexible transparent solid supercapacitor is shown in Figure 5. It can be seen from the figure that at different scan rates, the CV curves have a nearly rectangular structure, which is a typical capacitance characteristic of amorphous MnO ₂ , at a scan rate of 2mV/s, the area capacitance of the device can reach 167mF/cm ^-2 . Figure 6 is the cycle performance curve of the device under the condition of lateral flow charge and discharge. It can be seen that after 5000 cycles, the capacity of the device remains at about 99%, indicating that the device has good stability.

Example 3

Fabrication of ZnO@MnO ₂ Composite Nanoarray Interdigital Electrodes

1. Substrate selection: select PDMS as the substrate, and treat it with an oxygen plasma surface treatment machine for 2 minutes.

2. Design of interdigitated electrodes: use semiconductor device micromachining technology to process interdigitated electrode patterns on PDMS substrates. The pitch and finger width of the interdigitated electrodes used as a UV lithography mask are 2 μm. The operating conditions of the photolithography process are: the photoresist model used for ultraviolet lithography is AZ4620, the coating thickness is 4 microns, the coating speed is 1000 rpm, the pre-baking temperature is 80 degrees, the exposure time is 15s, and the developing time For 65s, an interdigitated electrode pattern was prepared on the PDMS substrate.

3. Preparation of collector electrode and ZnO seed layer: using magnetron sputtering, deposit a 60nm Pt film and a 10nm ZnO film on the PDMS substrate with interdigitated electrode patterns prepared in the second step above.

4. Prepare a three-dimensional ZnO nanorod array: put the PDMS substrate prepared in the third step above into a sealable container, and add deionized water and 0.55mol/L Zinc nitrate solution, 0.15mol/L polyvinylimine solution, 0.3mol/L hexamethylenetetramine solution and 75% ammonia water. After fully stirring, seal it, and then heat it in a water bath at 70°C for 13 hours to obtain a nano-zinc oxide array of about 6 microns;

5. Preparation of three-dimensional MnO ₂ array: The three-dimensional ZnO nanorod array is coated with cheap and environmentally friendly MnO ₂ material by three-electrode electrochemical deposition. The operating conditions of the electrochemical deposition are: the electrodeposition solution is 0.02mol/L The mixed solution of manganese nitrate and 0.1mol/L sodium nitrate, with the three-dimensional ZnO nanorod array interdigitated electrode prepared in step 4 as the working electrode, the platinum sheet as the counter electrode, and the calomel electrode as the reference electrode, the current density of electrodeposition 0.6mA/cm ² , the deposition time is 30min, and the MnO ₂ electrode material is electrodeposited around the ZnO nanorods to obtain MnO ₂ coated ZnO nanorod arrays;

6. Lift-Off process. The three-dimensional MnO ₂ array obtained in step 5 was soaked in acetone for 2 h, and ultrasonicated for 10 min to remove excess photoresist to obtain ZnO@MnO ₂ composite nano-array interdigitated electrodes.

Example 4

Fabrication of ZnO@MnO ₂ Composite Nanoarray Interdigital Electrodes

1. Substrate selection: select PMMA as the substrate, and treat it with an oxygen plasma surface treatment machine for 2 minutes.

2. Design of interdigitated electrodes: use semiconductor device micromachining technology to process interdigitated electrode patterns on PMMA substrates. The pitch and finger width of the interdigitated electrodes used as a UV lithography mask are 50 microns. The operating conditions of the photolithography process are: the photoresist model used for ultraviolet lithography is AZ4620, the coating thickness is 3.5 microns, the coating speed is 1500 rpm, the pre-baking temperature is 90 °C, the exposure time is 20s, and the developing time For 68s, an interdigitated electrode pattern was prepared on the PMMA substrate.

3. Preparation of collector electrode and ZnO seed layer: adopt magnetron sputtering mode to deposit 65nm Pt film and 15nm ZnO film on the PMMA substrate with interdigitated electrode pattern prepared in the above-mentioned 2nd step.

4. Preparation of ZnO nanorod array: Put the PMMA substrate prepared in the above step 3 into a sealable container, and add deionized water and 0.52mol/L of Zinc nitrate solution, 0.12mol/L polyvinylimine solution, 0.28mol/L hexamethylenetetramine solution and ammonia water with a mass fraction of 75%. After fully stirring, seal it, and then heat it in a water bath at 70°C for 5 hours to obtain a nano-zinc oxide array of about 6 microns;

5. Preparation of three-dimensional MnO ₂ array: The three-dimensional ZnO nanorod array is coated with cheap and environmentally friendly MnO ₂ material by three-electrode electrochemical deposition. The operating conditions of the electrochemical deposition are: the electrodeposition solution is 0.02mol/L The mixed solution of manganese nitrate and 0.1mol/L sodium nitrate, with the three-dimensional ZnO nanorod array interdigitated electrode prepared in step 4 as the working electrode, the platinum sheet as the counter electrode, and the calomel electrode as the reference electrode, the current density of electrodeposition 0.55mA/cm ² , the deposition time is 28min, electrodeposited and coated MnO ₂ electrode material around the ZnO nanorods to obtain MnO ₂ coated ZnO nanorod arrays;

6. Lift-Off process. The three-dimensional MnO ₂ array obtained in step 5 was soaked in acetone for 2 h, and ultrasonicated for 10 min to remove excess photoresist to obtain ZnO@MnO ₂ composite nano-array interdigitated electrodes.

The applicant declares that the present invention illustrates the detailed methods of the present invention through the above-mentioned examples, but the present invention is not limited to the above-mentioned detailed methods, that is, it does not mean that the present invention must rely on the above-mentioned detailed methods to be implemented. Those skilled in the art should understand that any improvement of the present invention, the equivalent replacement of each raw material of the product of the present invention, the addition of auxiliary components, the selection of specific methods, etc., all fall within the scope of protection and disclosure of the present invention.

Claims (10)

1. one kind is based on three-dimensional ZnO@MnO₂The preparation method of the ultracapacitor of composite Nano array interdigital electrode, its feature exists In described to be based on three-dimensional ZnO@MnO₂The ultracapacitor of composite Nano array interdigital electrode includes packaging bag and solid electrolytic Matter, also including ZnO@MnO₂Composite Nano array interdigital electrode, the solid electrolyte and the ZnO@MnO₂Composite Nano array Interdigital electrode is placed in the packaging bag, and the solid electrolyte is applied to the ZnO@MnO₂The interdigital electricity of composite Nano array On extremely；

It is described to be based on three-dimensional ZnO@MnO₂The preparation method of the ultracapacitor of composite Nano array interdigital electrode includes following step Suddenly：

1) solid electrolyte is prepared；

2) solid electrolyte is equably applied to ZnO@MnO₂In composite Nano array interdigital electrode；The ZnO@MnO₂It is compound The preparation method of nano-array interdigital electrode is：Using micro-nano technology technology, interdigital colelctor electrode is prepared in flexible transparent substrate, By solwution method on interdigital colelctor electrode growing three-dimensional ZnO nano-rod array, and using electrodeposition technology in three-dimensional ZnO nanorod Surrounding coats one layer of MnO₂Active material, prepares 3D flexible and transparent ZnO@MnO₂Composite Nano array interdigital electrode；

3) the ZnO@MnO of solid electrolyte will have been smeared₂Composite Nano array interdigital electrode is encapsulated, and obtains the ultracapacitor.

2. preparation method according to claim 1, it is characterised in that described ZnO@MnO₂The interdigital electricity of composite Nano array Three-dimensional ZnO nano-rod array and MnO of the pole by flexible transparent substrate and in flexible transparent substrate₂Material is constituted, the MnO₂ Material is coated on outside the three-dimensional ZnO nano-rod array.

3. preparation method according to claim 1, it is characterised in that the flexible transparent substrate be PET, PMMA or PDMS。

4. preparation method according to claim 1, it is characterised in that described ZnO@MnO₂The interdigital electricity of composite Nano array The active electrode width and electrode spacing of pole are 2-100 microns.

5. preparation method according to claim 1, it is characterised in that the ZnO@MnO₂Composite Nano array interdigital electrode Preparation method specifically include following steps：

1) substrate is selected：Selection flexible transparent substrate is simultaneously surface-treated to it；

2) interdigital electrode pattern is designed：Designed mask plate pattern, using semiconductor devices micro fabrication, adds over the substrate Work goes out interdigital electrode pattern；

3) prepared by colelctor electrode and ZnO Seed Layers：Pt films and ZnO film are deposited on the interdigital electrode pattern of the substrate；

4) three-dimensional ZnO nano-rod array interdigital electrode is prepared：By step 3) substrate is placed in sealable container, adds three ZnO nano-rod array precursor liquid is tieed up, is sealed after being sufficiently stirred for, then under condition of water bath heating, three-dimensional ZnO nanorod battle array is obtained Row interdigital electrode；

5) MnO is deposited₂：In step 4) MnO is coated on obtained three-dimensional ZnO nano-rod array₂, obtain MnO₂The three-dimensional ZnO of cladding Nanometer stick array interdigital electrode；

6) Lift-Off techniques：By MnO₂Unnecessary photoresist is removed in the three-dimensional ZnO nano-rod array interdigital electrode of cladding, is obtained To the ZnO@MnO of flexible and transparent₂Composite Nano array interdigital electrode.

6. preparation method according to claim 5, it is characterised in that step 2) the processing interdigital electrode pattern use purple Outer photoetching technique, concrete operations condition is：From model AZ4620 photoresist, spin coating thickness is 3-4 microns, spin coating speed For 1000-2000 revs/min, pre-bake temperature is 80-105 DEG C, and the time for exposure is 15-25s, and developing time is 65-70s.

7. preparation method according to claim 5, it is characterised in that step 3) the Pt films and ZnO film pass through magnetic Control sputtering mode is deposited, and the thickness of the Pt films is 60-70nm, and the thickness of the ZnO film is 10-20nm.

8. preparation method according to claim 5, it is characterised in that step 4) the three-dimensional ZnO nano-rod array forerunner Liquid is 0.5-0.55mol/L zinc nitrate solution, 0.1-0.15mol/L polyethylenimine solution, 0.25-0.3mol/L's 75% ammoniacal liquor and the mixed liquor of deionized water that hexamethylenetetramine solution, mass fraction are；The deionized water：Zinc nitrate is molten Liquid：Polyethylenimine solution：Hexamethylenetetramine solution：The volume ratio of ammoniacal liquor is 32:2:4:2:1；The heating water bath Temperature is 65-70 DEG C, and the time of the heating water bath is 5-13h.

9. preparation method according to claim 5, it is characterised in that in step 4) on the three-dimensional ZnO nano-rod array 10-15nm Pt films have also been coated by magnetron sputtering technique.

10. preparation method according to claim 5, it is characterised in that step 5) the deposition MnO₂Using three electrode electrochemicals Deposition is learned, the operating condition of the three-electrode electro Chemical deposition is：It is electric by work of three-dimensional ZnO nano-rod array interdigital electrode Pole, manganese nitrate and sodium nitrate mixed liquor are electrodeposit liquid, and platinized platinum is that calomel electrode is reference electrode, the electricity of electro-deposition to electrode Current density is 0.5-0.6mA/cm², electrodeposition time is 25-30min, electric around three-dimensional ZnO nano-rod array interdigital electrode Deposition cladding MnO₂。