Flexible zinc ion battery positive electrode constructed through 3D printing and preparation method and application thereof

Abstract

The invention discloses a flexible zinc ion battery positive electrode constructed through 3D printing and a preparation method and application thereof. Polyvinylidene fluoride and N-methyl pyrrolidone are mixed, heated and stirred to form gel, the carbon nanotube coated MOF-based composite material and carbon black are added, ball milling is performed, and printable positive ink is prepared; the method comprises the following steps: filling printable positive electrode ink into an injector, connecting the injector to an air pressure control device of a printer, uniformly extruding mild ink, after printing is completed, placing an obtained electrode in a ventilation cabinet, drying and removing a soldering flux. According to the flexible zinc ion battery positive electrode constructed through 3D printing, a three-dimensional network structure of a carbon nanotube coated MOF material and carbon black is prepared through a 3D printing method, rapid transmission of zinc ions is guaranteed, and the flexible zinc ion battery positive electrode has high specific capacity and long cycle stability, meanwhile has good flexibility, is simple in preparation process and short in time consumption and has good industrialization prospects.

Description

Technical Field

[0001] The present invention relates to the field of electrode technology, and in particular to a 3D-printed flexible zinc-ion battery positive electrode, and a preparation method and application thereof. Background Art

[0002] In recent years, the rapid development of microelectronics technology and the integration of electronic devices have placed higher demands on the area, safety, and energy density of energy storage devices. The poor safety of traditional energy storage devices, such as lithium-ion batteries, has limited their application and development. Among the new generation of energy storage devices, aqueous zinc-ion batteries have attracted widespread attention due to their high safety, environmental friendliness, and low cost.

[0003] Zinc (Zn) has abundant reserves in the earth's crust and is inexpensive; Zn metal can exist stably in the air, so the assembly and production of zinc-ion batteries can be carried out in the air, which greatly reduces production costs; the aqueous electrolyte used in zinc-ion batteries is non-toxic to the human body, does not pollute the environment, and does not cause safety problems such as combustion. Therefore, aqueous zinc-ion batteries are a very promising energy storage system. Despite this, the current research on aqueous zinc-ion battery positive electrode materials is still in its infancy. The most commonly used aqueous zinc-ion battery positive electrode material is MnO2, but the above positive electrode material contains Zn 2+ The problems of slow storage kinetics and easy dissolution of materials in the electrolyte, as well as the lack of flexibility of MnO2 electrodes produced by traditional coating processes, limit the further application of zinc-ion batteries in complex scenarios. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of the present invention is to propose a 3D printing-constructed flexible zinc-ion battery positive electrode and its preparation method and application. A carbon nanotube-coated UiO-66-NH2@MnO2 composite material positive electrode with a three-dimensional hierarchical network structure is prepared by a 3D printing method. The periodic pores constructed by 3D printing and the rich mesopores in the UiO-66-NH2@MnO2 composite material constitute a hierarchical pore structure, which ensures the rapid transmission of zinc ions and can alleviate the electrode deformation during charging and discharging. Therefore, the positive electrode has excellent rate performance and long cycle stability, and at the same time has good flexibility and can adapt to different microelectronic device usage scenarios. The preparation process is simple, time-saving, and has good industrialization prospects.

[0005] In order to solve the problems of the prior art, the technical solution adopted by the present invention is:

[0006] A method for preparing a flexible zinc-ion battery positive electrode by 3D printing, comprising the following steps:

[0007] S1. Preparation of printable positive electrode ink:

[0008] The polyvinylidene fluoride and N-methyl pyrrolidone are mixed, heated and stirred at 55-65° C. to form a gel, and then carbon nanotube-coated MOF-based composite material and carbon black are added, and ball milled for 1-3 hours to prepare a printable positive electrode ink, wherein the mass ratio of the polyvinylidene fluoride, N-methyl pyrrolidone, carbon nanotube-coated MOF-based composite material, and carbon black is 2-4:0.5-1:8-10:0.5-1;

[0009] S2.3D printing process:

[0010] The printable positive electrode ink is loaded into a syringe, which is connected to the air pressure control device of the printer. Then, the printer is started, the preset program of the 3D model is run, and the air pressure of the air pressure control device is adjusted to evenly extrude the gentle ink. After printing is completed, the obtained electrode is placed in a fume hood, dried, and the flux is removed to obtain a 3D printed flexible zinc-ion battery electrode.

[0011] As an improvement, the preparation method of the carbon nanotube-coated MOF-based composite material in step S1 is as follows:

[0012] Step 1, benzoic acid, zirconium tetrachloride, and 2-aminoterephthalic acid are weighed in a mass ratio of 4-4.5:0.5-1:0.3-0.7, mixed and added to N,N-dimethylformamide to obtain solution A, potassium permanganate and manganese sulfate monohydrate are weighed in a mass ratio of 3-3.5:5-5.5, and added to deionized water, and magnetically stirred for 1 hour to obtain solution B, which is then slowly added to solution A. The mixed solution is transferred to a polytetrafluoroethylene reactor, hydrothermally reacted at 120-140° C. for 20-24 hours, centrifuged, washed, and dried to obtain a UiO-66-NH2@MnO2 composite material;

[0013] Step 2: The UiO-66-NH2@MnO2 composite material is heated to 200-300°C under inert gas protection, and replaced with hydrogen after keeping warm for one hour. The temperature is raised to 450°C at a rate of 5°C / min, and then rapidly heated to 600-700°C at a rate of 20°C / min, and then the hydrogen is replaced with n-hexane. The reaction is kept warm for 20-40 minutes. After the insulation is completed, the n-hexane is replaced with an inert gas, and the mixture is cooled to room temperature to obtain a carbon nanotube-coated MOF-based composite material.

[0014] A further improvement is that in step T2, the ventilation rate of the hydrogen is 120-150 mg / min, and the ventilation rate of the n-hexane is 0.1-0.3 mL / min.

[0015] The 3D printed flexible zinc-ion battery positive electrode prepared by the above preparation method has a periodic layered grid, which is conducive to electrolyte penetration and is highly flexible. It can still maintain structural stability when bent at 45°-180°. The capacity retention rate of the 3D printed flexible zinc-ion battery positive electrode after 100 cycles of charge and discharge after bending is still 95.3%.

[0016] The above-mentioned 3D printing construction of a flexible zinc-ion battery positive electrode is used in the preparation of zinc-ion batteries.

[0017] A zinc ion battery comprising the above-mentioned 3D-printed flexible zinc ion battery positive electrode, wherein the zinc ion battery has a specific capacity of 97.6 mAh / g at a current density of 2 A / g and a capacity retention rate of 92.3% after 1000 cycles of charge and discharge.

[0018] Beneficial effects:

[0019] Compared with the prior art, the present invention uses 3D printing technology to achieve layer-by-layer printing and positive electrode printing without a metal current collector, further increasing the mass load and thus the area capacity. The prepared 3D printed flexible zinc ion battery positive electrode has a three-dimensional layered network structure, which ensures the rapid transmission of zinc ions, has high specific capacity and long cycle stability. In addition, the electrode prepared by the present invention has good flexibility and is suitable for a variety of complex scenarios. The preparation process is simple and time-consuming, providing a new direction for the commercial application of aqueous zinc ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Flow chart of the preparation of a 3D printed flexible zinc ion battery positive electrode prepared in Example 3 of the present invention;

[0021] Figure 2 The 3D-printed positive electrode prepared in Example 3 of the present invention and its flexibility test;

[0022] Figure 3 This is a SEM photo of the 3D printed flexible electrode prepared in Example 3 of the present invention;

[0023] Figure 4 This is a rate performance diagram of the 3D printed flexible electrode prepared in Example 3 of the present invention;

[0024] Figure 5 This is a graph showing the long cycle performance of the 3D printed flexible electrode prepared in Example 3 of the present invention;

[0025] Figure 6 The capacity retention rate of the 3D printed flexible electrode prepared in Example 3 of the present invention after 100 cycles of charge and discharge after bending. DETAILED DESCRIPTION

[0026] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0027] Example 1

[0028] A method for preparing a flexible zinc-ion battery positive electrode by 3D printing, comprising the following steps:

[0029] T1. 4 g of benzoic acid, 0.5 g of zirconium tetrachloride, and 0.3 g of 2-aminoterephthalic acid were mixed and added to 200 mL of N,N-dimethylformamide to obtain solution A. 3 g of potassium permanganate and 5 g of manganese sulfate monohydrate were added to 150 mL of deionized water and magnetically stirred for 1 hour to obtain solution B. Solution A was then slowly added to the mixture. The mixed solution was transferred to a hydrothermal reactor and hydrothermally reacted at 120°C for 20 hours. The mixture was centrifuged and washed three times with deionized water and ethanol alternately. The mixture was then dried at 60°C for 24 hours to obtain the UiO-66-NH2@MnO2 material.

[0030] T2. Under nitrogen protection, the UiO-66-NH2@MnO2 material was heated to 300°C, and then the nitrogen was replaced with hydrogen at a hydrogen flow rate of 120 mg / min. The temperature was raised to 450°C at a rate of 5°C / min, and then the temperature was rapidly raised to 600°C at a rate of 20°C / min, and the hydrogen was replaced with n-hexane at a n-hexane flow rate of 0.1 mL / min. The reaction was kept warm for 20 minutes. After the insulation was completed, the n-hexane was replaced with nitrogen, and the mixture was cooled to room temperature to obtain a carbon nanotube-coated MOF-based composite material.

[0031] S1. Preparation of Printable Cathode Ink

[0032] 2 g of polyvinylidene fluoride and 0.5 g of N-methylpyrrolidone were mixed and heated to 55°C, stirred to form a gel, and 8 g of the carbon nanotube-coated MOF-based composite prepared in step T2 and 0.5 g of carbon black were added. The mixture was ball-milled for 1 h to prepare a printable positive electrode ink.

[0033] S2.3D printing process

[0034] Load the printable positive electrode ink into a 100 μm needle syringe, connect the syringe to the air pressure control device of the 3D printer, then start the 3D printer, run the preset program of the 3D model, adjust the air pressure of the air pressure control device, and evenly squeeze the printing ink at a pressure of 50 kPa. After printing is completed, place the obtained electrode in a fume hood and dry it naturally.

[0035] Example 2

[0036] A method for preparing a flexible zinc-ion battery positive electrode by 3D printing, comprising the following steps:

[0037] T1. 4.5 g of benzoic acid, 1 g of zirconium tetrachloride, and 0.7 g of 2-aminoterephthalic acid were mixed and added to 200 mL of N,N-dimethylformamide to obtain solution A. 3.5 g of potassium permanganate and 5.5 g of manganese sulfate monohydrate were added to 200 mL of deionized water and magnetically stirred for one hour to obtain solution B, which was then slowly added to solution A. The mixed solution was transferred to a hydrothermal reactor and hydrothermally reacted at 140°C for 24 hours. The mixture was centrifuged and washed three times with deionized water and ethanol alternately. The mixture was then dried at 60°C for 24 hours to obtain the UiO-66-NH2@MnO2 material.

[0038] T2. Under nitrogen protection, the UiO-66-NH2@MnO2 material was heated to 300°C, and then the nitrogen was replaced with hydrogen at a hydrogen flow rate of 150 mg / min. The temperature was raised to 450°C at a rate of 5°C / min, and then the temperature was rapidly raised to 600°C at a rate of 20°C / min. The hydrogen was replaced with n-hexane at a n-hexane flow rate of 0.3 mL / min. The reaction was kept warm for 20 minutes. After the insulation was completed, the n-hexane was replaced with nitrogen, and the mixture was cooled to room temperature to obtain a carbon nanotube-coated MOF-based composite material.

[0039] S1. Preparation of a printable positive electrode ink: 4 g of polyvinylidene fluoride and 1 g of N-methylpyrrolidone were mixed and heated to 65°C and stirred to form a gel. 10 g of the carbon nanotube-coated MOF-based composite material prepared in Preparation Example 2 and 1 g of carbon black were added and ball-milled for 3 h to prepare a printable positive electrode ink.

[0040] S2.3D printing process

[0041] Load the printable positive electrode ink into a 100 μm needle syringe, connect the syringe to the air pressure control device of the 3D printer, then start the 3D printer, run the preset program of the 3D model, adjust the air pressure of the air pressure control device, and evenly squeeze the printing ink at a pressure of 50 kPa. After printing is completed, place the obtained electrode in a fume hood and dry it naturally.

[0042] Example 3

[0043] A method for preparing a flexible zinc-ion battery positive electrode by 3D printing, comprising the following steps:

[0044] T1. 4.2 g of benzoic acid, 0.7 g of zirconium tetrachloride, and 0.3-0.7 g of 2-aminoterephthalic acid were mixed and added to 200 mL of N,N-dimethylformamide to obtain Solution A. 3.3 g of potassium permanganate and 5.2 g of manganese sulfate monohydrate were added to 200 mL of deionized water and magnetically stirred for one hour to obtain Solution B, which was then slowly added to Solution A. The mixed solution was transferred to a hydrothermal reactor and hydrothermally reacted at 130°C for 20 hours. The reaction was centrifuged, washed alternately with deionized water and ethanol three times, and dried at 60°C for 24 hours to obtain UiO-66-NH2@MnO2 material.

[0045] T2. Under nitrogen protection, the UiO-66-NH2@MnO2 material was heated to 250°C, and then the nitrogen was replaced with hydrogen at a hydrogen flow rate of 120 mg / min. The temperature was raised to 450°C at a rate of 5°C / min, and then the temperature was rapidly raised to 600°C at a rate of 20°C / min. The hydrogen was replaced with n-hexane at a n-hexane flow rate of 0.2 mL / min. The reaction was kept warm for 20 minutes. After the insulation was completed, the n-hexane was replaced with nitrogen, and the material was cooled to room temperature to obtain a carbon nanotube-coated MOF-based composite material.

[0046] S1. Preparation of printable positive electrode ink:

[0047] 3 g of polyvinylidene fluoride and 0.7 g of N-methylpyrrolidone were mixed and heated to 60° C., stirred to form a gel, and 9 g of the carbon nanotube-coated MOF-based composite material prepared in Preparation Example 3 and 0.7 g of carbon black were added. The mixture was ball-milled for 2 h to prepare a printable positive electrode ink.

[0048] S2.3D printing process

[0049] Load the printable positive electrode ink into a 100 μm needle syringe, connect the syringe to the air pressure control device of the 3D printer, then start the 3D printer, run the preset program of the 3D model, adjust the air pressure of the air pressure control device, and evenly squeeze the printing ink at a pressure of 50 kPa. After printing is completed, place the obtained electrode in a fume hood and dry it naturally.

[0050] Figure 2 The positive electrode prepared in Example 3 was subjected to flexibility tests by bending it 90° and 180°, respectively. As can be seen from the figure, the positive electrode material of the present invention still has an intact structure after bending.

[0051] Comparative Example 1

[0052] Compared with Example 3, the difference is that step T2 is not performed, and the carbon nanotube-coated MOF-based composite material in step S1 is replaced by the UiO-66-NH2@MnO2 material prepared in step T1.

[0053] Comparative Example 2

[0054] Compared with Example 3, the difference is that in step T1, solution B is not added to solution A. Instead, solution A is hydrothermally reacted at 130°C for 20 hours, centrifuged, washed three times with deionized water and ethanol, and dried at 60°C for 24 hours to obtain pure UiO-66-NH2 material. In step S1, the carbon nanotube-coated MOF-based composite material is replaced with the prepared pure UiO-66-NH2 material.

[0055] The remaining steps are the same as step S2 of Example 3.

[0056] The 3D printed flexible zinc ion battery positive electrode prepared in Examples 1-3 and Comparative Examples 1-2 was assembled into an aqueous zinc ion button cell (the negative electrode was zinc metal, the electrolyte was 2 mol / L ZnSO4 solution, and the separator was glass fiber) and its pseudocapacitance contribution ratio (%) at different scan rates was tested. The results are shown in Table 1.

[0057] Table 1 Pseudocapacitance contribution ratio of different cathode materials at different scan rates (%)

[0058]

[0059] As can be seen from the above table, the 3D printed flexible zinc ion batteries prepared in Examples 1-3 of the present invention have a higher capacitance contribution ratio, and Example 3 has the highest capacitance contribution, indicating that it has the ability to rapidly store optimal charges and can still maintain excellent electrochemical performance at high current density.

[0060] The 3D printed flexible zinc ion battery cathode prepared in Example 3 was assembled into an aqueous zinc ion button cell (the negative electrode was zinc metal, the electrolyte was 2 mol / L ZnSO4 solution, and the separator was glass fiber). Constant current charge and discharge tests were performed to obtain the discharge specific capacity (mAh / g) at different current densities. The results are shown in Table 1. Figure 4 As can be seen from the figure, the 3D printed flexible zinc ion battery prepared in Example 3 of the present invention still has a specific capacity of 97.6 mAh / g at a current density of 2 A / g, and has excellent rate performance.

[0061] The 3D printed flexible zinc ion battery positive electrode prepared in Example 3 was assembled into an aqueous zinc ion button battery (the negative electrode was zinc metal, the electrolyte was 2 mol / L ZnSO4 solution, and the separator was glass fiber). Cyclic charge and discharge tests were performed at a current density of 1 A / g. The results are shown in FIG. Figure 5 As can be seen from the figure, the 3D printed flexible zinc ion battery prepared in Example 3 of the present invention has a capacity retention rate of 92.3% after 1000 cycles of charge and discharge, and has excellent long-cycle stability.

[0062] The 3D printed flexible zinc ion battery cathode prepared in Example 3 was assembled into a soft pack battery and the long cycle performance was tested after being bent 100 times. The results are shown in FIG. Figure 6 As can be seen from the figure, the 3D printed flexible zinc ion battery positive electrode prepared in Example 3 of the present invention has a capacity retention rate of 95.3% after 100 cycles of charge and discharge after bending, showing excellent flexibility.

Claims

1. A method for preparing a flexible zinc ion battery positive electrode by 3D printing, characterized in that: The following steps are involved: S1. Preparation of printable positive electrode ink: The polyvinylidene fluoride and N-methyl pyrrolidone are mixed, heated and stirred at 55-65° C. to form a gel, and then carbon nanotube-coated MOF-based composite material and carbon black are added, and ball milled for 1-3 hours to prepare a printable positive electrode ink, wherein the mass ratio of the polyvinylidene fluoride, N-methyl pyrrolidone, carbon nanotube-coated MOF-based composite material, and carbon black is 2-4:0.5-1:8-10:0.5-1; S2.3D printing process: The printable positive electrode ink is loaded into a syringe, which is connected to the air pressure control device of the printer. Then, the printer is started, the preset program of the 3D model is run, and the air pressure of the air pressure control device is adjusted to evenly extrude the gentle ink. After printing is completed, the obtained electrode is placed in a fume hood and dried to obtain a 3D printed flexible zinc-ion battery electrode.

2. The method for preparing a flexible zinc ion battery positive electrode constructed by 3D printing according to claim 1, characterized in that: The preparation method of the carbon nanotube-coated MOF-based composite material in step S1 is as follows: Step 1, benzoic acid, zirconium tetrachloride, and 2-aminoterephthalic acid are weighed and mixed in a mass ratio of 4-4.5:0.5-1:0.3-0.7, and then added to N,N-dimethylformamide to obtain solution A, potassium permanganate and manganese sulfate monohydrate are weighed in a mass ratio of 3-3.5:5-5.5, and then added to deionized water, magnetically stirred for 1 hour to obtain solution B, and then slowly added to solution A. The mixed solution is transferred to a polytetrafluoroethylene reactor, hydrothermally reacted at 120-140°C for 20-24 hours, centrifuged, washed, and dried to obtain UiO-66-NH2@MnO2 material; Step 2: Under the protection of inert gas, the UiO-66-NH2@MnO2 material is heated to 200-300°C, kept warm for 1 hour, and then replaced with hydrogen. The temperature is raised to 450°C at a rate of 5°C / min, and then rapidly heated to 600-700°C at a rate of 20°C / min, and then the hydrogen is replaced with n-hexane. The reaction is kept warm for 20-40 minutes. After the insulation is completed, the n-hexane is replaced with an inert gas, and the mixture is cooled to room temperature to obtain a carbon nanotube-coated MOF-based composite material.

3. The method for preparing a flexible zinc ion battery positive electrode constructed by 3D printing according to claim 2, characterized in that: In step T2, the hydrogen gas flow rate is 120-150 mg / min, and the n-hexane gas flow rate is 0.1-0.3 mL / min.

4. A 3D printed flexible zinc ion battery positive electrode prepared by any one of the preparation methods of claims 1-3, characterized in that: The 3D printed flexible zinc-ion battery positive electrode has a periodic layered grid, which is conducive to electrolyte penetration and is highly flexible. It can still maintain structural stability when bent at 45°-180°. The capacity retention rate of the 3D printed flexible zinc-ion battery positive electrode after 100 cycles of charge and discharge after bending is still 95.3%.

5. Application of the 3D printed flexible zinc ion battery positive electrode constructed based on claim 4 in the preparation of a zinc ion battery.

6. A zinc ion battery, characterized in that: The 3D-printed flexible zinc-ion battery positive electrode according to claim 4 has a specific capacity of 97.6 mAh / g at a current density of 2 A / g, and a capacity retention rate of 92.3% after 1000 cycles of charge and discharge.

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