A light-assisted charging aqueous zinc ion battery and a preparation method thereof

Abstract

The application provides a light-assisted charging aqueous zinc ion battery and a preparation method thereof, and provides a light-assisted charging aqueous zinc ion battery, which comprises a light cathode, a diaphragm, an electrolyte, a zinc anode and a battery shell, the light cathode is a vanadium oxide compound light cathode, the zinc anode is a metal zinc sheet, the electrolyte is a zinc salt aqueous solution, and the light-assisted charging aqueous zinc ion battery is packaged in a battery shell with a cathode side opening, the vanadium oxide compound light cathode and the metal zinc sheet anode are separated by a diaphragm, and the diaphragm is filled with electrolyte on both sides. The application can realize the light-assisted charging aqueous zinc ion battery which can collect solar energy and store at the same time, and improve the electrochemical performance of the aqueous zinc ion battery.

Description

Technical Field

[0001] This invention belongs to the field of solar energy and energy storage, and relates to a photo-assisted charging aqueous zinc-ion battery and its preparation method. Background Technology

[0002] Developing new energy sources, achieving energy transition, and building a green and low-carbon energy system are important measures to achieve the "dual carbon" goals. Currently, vigorously developing clean and efficient renewable energy has become one of the key areas of technological research and development in the energy sector. Among these, the efficient utilization of solar energy has become crucial for renewable energy development. However, the intermittent nature of solar energy leads to unstable output from solar cells. Therefore, traditional solar energy applications typically include a separate energy harvesting component (such as photovoltaic solar cells) and a rechargeable energy storage component (such as batteries and supercapacitors). This assembly design not only increases the space occupied by the equipment, but also often results in a mismatch between the output voltage of the energy harvesting component and the voltage required by the energy storage device, significantly increasing costs and energy losses. Therefore, in order to utilize solar energy more effectively, breaking away from the inherent structure of traditional solar cells and adopting new concepts, structures, and devices to achieve efficient solar energy utilization is currently a key research focus in the solar energy and energy storage fields.

[0003] Recently, the emergence of photovoltaic-assisted charging energy storage devices has provided an effective way to directly realize energy conversion and storage involving solar energy. Among them, zinc-ion batteries (ZIBs) are expected to become the next generation of new energy storage systems due to their abundant reserves, environmental friendliness, and high volumetric capacity. Therefore, photovoltaic-assisted charging batteries based on zinc-ion batteries can not only solve the mismatch problem between energy harvesting output voltage and storage input voltage faced by traditional solar cell systems, but also eliminate the need for additional voltage conversion equipment, reducing costs and energy losses, which is also very beneficial for large-scale energy storage. Based on this, the present invention provides a photovoltaic-assisted charging aqueous zinc-ion battery. Summary of the Invention

[0004] The purpose of this invention is to provide a light-assisted charging aqueous zinc-ion battery that can simultaneously collect and store solar energy, thereby improving the electrochemical performance of the aqueous zinc-ion battery.

[0005] The objective of this invention is achieved as follows: a photo-assisted charging aqueous zinc-ion battery is provided, comprising a photocathode, a separator, an electrolyte, a zinc anode, and a battery casing. The photocathode is a vanadium oxide photocathode, the zinc anode is a zinc sheet, and the electrolyte is an aqueous zinc salt solution. The photo-assisted charging aqueous zinc-ion battery encapsulates the vanadium oxide photocathode and the zinc sheet anode within a battery casing with an opening on the cathode side. The vanadium oxide photocathode and the zinc sheet anode are separated by a separator, and the separator is filled with electrolyte on both sides.

[0006] The preparation of a photo-assisted charging aqueous zinc-ion battery includes the following steps:

[0007] Step 1: Vanadium chloride and terephthalic acid are dissolved in deionized water and stirred until fully dissolved to obtain a brownish-red mixed solution. The mixed solution is transferred to an autoclave for hydrothermal reaction. After the reaction is complete, the solution is washed with deionized water and dried to obtain a yellowish-green powdered vanadium metal-organic framework precursor. Then, the vanadium metal-organic framework precursor and tannic acid are dispersed in a mixed solution of deionized water and ethanol and etched at room temperature. Finally, the etched material is transferred to a tube furnace under argon atmosphere for annealing to obtain a vanadium oxide photocathode material.

[0008] Step 2: Mix the vanadium oxide photocathode material obtained in Step 1, conductive carbon black, and binder to form a slurry, and coat it onto conductive glass to obtain a vanadium oxide photocathode.

[0009] Step 3: Assemble the vanadium oxide photocathode, separator, zinc metal anode and electrolyte obtained in Step 2 into a coin cell with an opening on the cathode side. This cell is a photo-assisted charging aqueous zinc-ion battery.

[0010] Preferably, the molar ratio of vanadium chloride and terephthalic acid in step one is (0.5-2):1.

[0011] Preferably, the hydrothermal reaction in step one is carried out at a temperature of 180–200°C for 24–48 hours.

[0012] Preferably, the mass ratio of the vanadium metal-organic framework precursor to tannic acid in step one is (1-2):(0.5-1).

[0013] Preferably, the room temperature etching time in step one is 10 to 30 minutes.

[0014] Preferably, the annealing in step one is a two-step annealing. The first annealing temperature is 200–300℃, and the time is 30–60 min. The second annealing temperature is 500–600℃, and the time is 60–120 min. The heating rate for both steps is 1–5℃ / min. -1 .

[0015] Preferably, the mass ratio of the vanadium oxide photocathode material, conductive carbon black and binder in step two is (60-80):(10-20):(10-20).

[0016] Preferably, the diaphragm mentioned in step three is a cellulose diaphragm.

[0017] Preferably, the zinc sheet anode mentioned in step three is made of high-purity zinc foil with a thickness of 0.1 to 0.3 mm.

[0018] Preferably, the electrolyte in step three is selected from one or more of zinc trifluoromethanesulfonate, zinc sulfate, zinc chloride, and zinc perchlorate, and the concentration is 0.5–3 mol / L. -1 .

[0019] Preferably, the diameter of the circular hole on the cathode side described in step three is 6-10 mm.

[0020] Compared with existing technologies, the advantages of this invention are: This invention provides a novel photo-assisted charging aqueous zinc-ion battery. The battery simultaneously achieves in-situ solar energy conversion and charge storage. Through the integrated photocathode design, it not only solves the mismatch problem between the energy harvesting output voltage and the storage input voltage faced by traditional solar cell systems, but also eliminates the need for additional voltage conversion equipment, reducing costs and energy losses, which is highly advantageous for large-scale energy storage.

[0021] The photo-assisted charging aqueous zinc-ion battery prepared in this invention, when photo-assisted charging is performed using a xenon lamp light source, achieves a charging efficiency of 0.2 A g. -1 The reversible discharge specific capacity at current density is as high as 468.7 mAh g. -1 It is 1.7 times that under non-illuminated conditions. When the current density is 2A g... -1 The reversible specific capacity after 100 cycles under xenon lamp light source conditions is still 175 mAh g. -1 The efficiency is significantly higher than under non-sunlight conditions. Furthermore, the photo-assisted charging aqueous zinc-ion battery described in this invention features a simple structure, environmental friendliness, low cost, and high safety, achieving an effective combination and efficient utilization of solar energy and energy storage systems. Attached Figure Description

[0022] Figure 1 This invention relates to the structure of a light-assisted charging aqueous zinc-ion battery.

[0023] Figure 2 This is a schematic diagram of the mechanism of the light-assisted charging of the present invention.

[0024] Figure 3 These are scanning electron microscope images and ultraviolet absorption spectra of vanadium oxide photocathode materials.

[0025] Figure 4 The light-assisted charging aqueous zinc-ion battery provided in this embodiment has a scan rate of 1.0 mV / s under both illuminated and unilluminated conditions. -1 Comparison of cyclic voltammetry curves.

[0026] Figure 5 The light-assisted charging aqueous zinc-ion battery provided in this embodiment has a current density of 0.2 A g under both illuminated and non-illuminated conditions. -1A comparison of charge and discharge curves.

[0027] Figure 6 The photo-assisted charging aqueous zinc-ion battery provided in this embodiment has a current density of 2.0 A g under both illuminated and non-illuminated conditions. -1 Comparison chart of cyclic performance.

[0028] Figure 7 This is a comparison chart of the rate performance of the light-assisted charging aqueous zinc-ion battery provided in the embodiment under both light and non-light conditions. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0030] This invention provides a photo-assisted charging aqueous zinc-ion battery. The overall concept of this embodiment is to develop a photocathode that simultaneously collects solar energy and stores electrochemical energy, and to construct an aqueous zinc-ion battery that can achieve photo-assisted charging using this photocathode.

[0031] Appendix Figure 1 As shown, a light-assisted charging aqueous zinc-ion battery includes a cathode shell with a circular optical window, conductive glass, a photocathode, a separator, an electrolyte, a zinc anode, and an anode shell.

[0032] To simultaneously achieve solar energy collection and storage, the selected photocathode material not only needs to have a suitable bandgap for light absorption in the visible spectrum, enabling the excitation of holes and electrons under illumination, but also needs to possess the ability to store zinc ions. Therefore, the photocathode material described in this invention is a vanadium oxide compound with a bandgap width of 2.2 eV. Its photo-assisted charging mechanism is as follows. Figure 2 As shown, electrons are excited to the conduction band of the vanadium oxide compound under illumination, then transported through conductive carbon black to the conductive glass, and subsequently returned to the zinc anode via the external circuit. Simultaneously, due to the blocking effect of the conductive carbon black on hole transport, zinc ions stored in the vanadium oxide compound are deposited onto the zinc anode surface via the electrolyte, realizing the entire photo-assisted charging process. Due to the photo-assisted charging effect, the electrochemical performance of the aqueous zinc-ion battery in this invention is significantly improved.

[0033] The technical solutions claimed in this invention will be further described below through some embodiments and accompanying drawings. However, the embodiments are for explaining the implementation of the present invention and do not exceed the scope of the subject matter of the present invention, nor is the scope of protection of the present invention limited by the embodiments. Unless otherwise specified, the materials and reagents used in this invention can be obtained from commercially available products in the art.

[0034] Example 1

[0035] Preparation of vanadium oxide photocathode materials:

[0036] (1) Dissolve 0.9 g vanadium chloride (VCl3), 0.5 g terephthalic acid (H2BDC) and 0.02 g hexadecyltrimethylammonium bromide (CTAB) in 10 mL of deionized water (DI) to obtain a uniform brownish-brown solution; then transfer the obtained solution to a high-pressure reactor and hydrothermally react at 200 °C for 48 h; then centrifuge, wash and dry with N,N dimethylformamide (DMF) to obtain a yellowish-green precursor powder.

[0037] (2) 0.3g of precursor powder and 0.15g of tannic acid (TA) were ultrasonically dispersed in 150ml of ethanol. The above solutions were then mixed and stirred for 10min, and washed and dried by centrifugation with ethanol to obtain precursor powder after organic weak acid etching treatment.

[0038] (3) Finally, the precursors etched with the above-mentioned organic weak acid were annealed at 200℃ for 1 h and 600℃ for 1 h in an argon atmosphere, with a heating rate of 1℃ / min. -1 Obtain vanadium oxide photocathode material (with attachment) Figure 3 ).

[0039] Example 2

[0040] Preparation of vanadium oxide photocathode: Vanadium oxide photocathode material, acetylene black, and polyvinylidene fluoride were mixed in an agate mortar with manual stirring at a mass ratio of 70:20:10 to obtain a slurry; then, the slurry was coated onto the conductive side of a circular conductive glass with a diameter of 8 mm. The coating amount of the slurry was based on the substrate area at a standard ratio of 2.0 mg / cm². -2 Then, the conductive glass coated with the mixed slurry was dried in a vacuum oven at a pressure of 270 Pa for 12 hours to obtain a vanadium oxide photocathode.

[0041] Example 3

[0042] Pre-treatment of zinc metal anode: A 20μm thick sheet of zinc metal is polished with sandpaper of 2000 and 3000 grit respectively to remove the oxide layer on the surface of the zinc metal, thereby exposing the zinc metal and obtaining the zinc metal anode.

[0043] Example 4

[0044] Preparation of aqueous zinc salt electrolyte: Dissolve 3 mol of zinc trifluoromethanesulfonate in deionized water, and stir at 500 rpm with a magnetic stirrer. -1 The aqueous zinc salt electrolyte was obtained by stirring at a certain rate for 12 hours.

[0045] Example 5

[0046] Assemble a light-assisted charging zinc-ion battery:

[0047] (1) Place the anode shell flat on the panel with the opening facing upwards;

[0048] (2) Place the spring sheet and the current collector sequentially on the anode shell;

[0049] (3) Place the polished zinc sheet on the current collector;

[0050] (4) Place the diaphragm on the zinc sheet;

[0051] (5) Add 3-5 drops of aqueous zinc salt electrolyte to the diaphragm to wet the diaphragm;

[0052] (6) Place the prepared vanadium oxide photocathode coating material side down at the center of the diaphragm;

[0053] (7) Cover the cathode shell to obtain a prototype photo-assisted charging aqueous zinc-ion battery;

[0054] (8) Press the prototype aqueous zinc-ion battery obtained in step (7) with a pressure of 50 MPa to obtain an aqueous zinc-ion battery device that can be charged by light.

[0055] Example 6

[0056] Performance Testing: The assembled aqueous zinc-ion batteries were tested under both illuminated and unilluminated conditions, including cyclic voltammetry, charge-discharge curves, cycle performance, and rate performance. Illumination was performed using a xenon lamp with a wavelength range of 320-2500 nm and a visible light output power of 19.6 W. The power current was set to 15 A, and the light spot size was adjusted to precisely cover the optical window of the device. Test results are attached. Figure 4-7 As shown.

[0057] Appendix Figure 4 This is a comparison of the cyclic voltammograms of a photo-assisted charging aqueous zinc-ion battery device obtained according to the technical solution of this application under both illuminated and unilluminated conditions. It shows that the peak current of the redox peak of the aqueous zinc-ion battery device obtained according to the technical solution of this application increases significantly under illuminated conditions. Quantitative calculations show that the area of ​​the cyclic voltammogram of this device increases by 92.3% under illuminated conditions.

[0058] Appendix Figure 5 This is a comparison of the charge-discharge curves of the light-assisted charging aqueous zinc-ion battery device obtained according to the technical solution of this application under both illuminated and non-illuminated conditions. It shows that the aqueous zinc-ion battery device obtained according to the technical solution of this application exhibits increased discharge reaction potential and decreased charging reaction potential under illuminated conditions, resulting in reduced polarization. Therefore, the discharge specific capacity of this device under illuminated conditions reaches as high as 468.7 mAh g⁻¹. -1This is 1.72 times the discharge specific capacity under non-illuminated conditions. This photoelectric hybrid cathode, which assembles a photoelectrode with a zinc-ion battery cathode, can simultaneously achieve solar energy collection and energy storage, improving the electrochemical performance and packaging efficiency of the device, reducing device size and ohmic transmission loss, and lowering manufacturing costs.

[0059] Appendix Figure 6 This is a comparison chart of the rate performance of a light-assisted aqueous zinc-ion battery device obtained from the technical solution of this application under both illuminated and unilluminated conditions. It shows that the rate performance of the device is significantly improved under illuminated conditions, reaching 2A g. -1 It still has 259 mAh g at a current density. -1 Its reversible discharge specific capacity is 1.8 times that under non-light conditions.

[0060] Appendix Figure 7 This is a comparison chart of the cycle performance of a light-assisted charging aqueous zinc-ion battery device obtained from the technical solution of this application under both light and non-light conditions, with a current density of 2A g. -1 The reversible specific capacity of the device after 100 cycles under both illuminated and non-illuminated conditions was 175 mAh g and 101 mAh g, respectively. -1 This indicates that the photo-assisted aqueous zinc-ion battery obtained by the technical solution in this application embodiment has good cycle stability.

[0061] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a photo-assisted charging aqueous zinc-ion battery, characterized in that, Includes the following steps: Step 1: Dissolve vanadium chloride and terephthalic acid in deionized water and stir until fully dissolved to obtain a brownish-red mixed solution; transfer the mixed solution to an autoclave for hydrothermal reaction; after the reaction is complete, wash and dry with deionized water to obtain a yellowish-green powder vanadium metal-organic framework precursor; disperse the vanadium metal-organic framework precursor and tannic acid in a mixed solution of deionized water and ethanol for room temperature etching; transfer the etched material to a tube furnace under argon atmosphere for annealing to obtain a vanadium oxide photocathode material; Step 2: Mix the vanadium oxide photocathode material obtained in Step 1, conductive carbon black and binder to form a slurry, and coat it on conductive glass to obtain a vanadium oxide photocathode. Step 3: Assemble the vanadium oxide photocathode, separator, zinc metal anode and electrolyte obtained in Step 2 into a coin cell with an opening on the cathode side. This cell is a photo-assisted charging aqueous zinc-ion battery.

2. The method for preparing a photo-assisted charging aqueous zinc-ion battery according to claim 1, characterized in that: The molar ratio of vanadium chloride and terephthalic acid mentioned in step one is (0.5~2):

1.

3. The method for preparing a photo-assisted charging aqueous zinc-ion battery according to claim 1, characterized in that: The temperature of the hydrothermal reaction described in step one is 180~200℃. o C, the time is 24~48h.

4. The method for preparing a photo-assisted charging aqueous zinc-ion battery according to claim 1, characterized in that: The mass ratio of the vanadium metal-organic framework precursor to tannic acid in step one is (1~2):(0.5~1).

5. The method for preparing a photo-assisted charging aqueous zinc-ion battery according to claim 1, characterized in that: The room temperature etching time mentioned in step one is 10~30 minutes.

6. The method for preparing a photo-assisted charging aqueous zinc-ion battery according to claim 1, characterized in that: The annealing described in step one is a two-step annealing process, with the first annealing temperature being 200~300℃. o C, time is 30~60min; second annealing temperature is 500~600℃. o Temperature, time 60-120 min, heating rate 1-5 o C min -1 .

7. The method for preparing a photo-assisted charging aqueous zinc-ion battery according to claim 1, characterized in that: The mass ratio of the vanadium oxide photocathode material, conductive carbon black and binder mentioned in step two is (60~80):(10~20):(10~20).

8. The method for preparing a photo-assisted charging aqueous zinc-ion battery according to claim 1, characterized in that: The diaphragm mentioned in step three is a cellulose diaphragm; the zinc anode mentioned in step three is made of high-purity zinc foil with a thickness of 0.1~0.3 mm; the electrolyte mentioned in step three is selected from one or more of zinc trifluoromethanesulfonate, zinc sulfate, zinc chloride, and zinc perchlorate in aqueous solution, with a concentration of 0.5~3 mol L. -1 .

9. The method for preparing a photo-assisted charging aqueous zinc-ion battery according to claim 1, characterized in that: The circular hole on the cathode side mentioned in step three has a diameter of 6~10mm.

Images