Preparation and application of zinc-iodine battery positive electrode carrier with boat-in-bottle structure

Abstract

The application discloses a kind of bottle-in-bottle structure silver porous carbon composite material as zinc iodine battery positive carrier and its preparation and application in zinc iodine battery positive electrode.The bottle-in-bottle structure silver porous carbon composite material Ag@KJ600 is synthesized by ultrasonic immersion method, dried, calcined, ground with I2 in argon protection environment, sealed and heated for 12 hours to obtain Ag@KJ600 / I2.When the composite material is used as iodine positive carrier, it can chemically adsorb polyiodide formed during the cycle process, inhibit the shuttle effect of polyiodide, and further reduce the corrosion of negative zinc and the loss of active material.Ag@KJ600 / I2 active material can be applied to zinc iodine battery iodine positive electrode, and excellent electrochemical performance is shown.

Description

Technical Field

[0001] This invention belongs to the field of zinc-iodine battery technology, specifically relating to the preparation and application of a silver@porous carbon composite iodine cathode carrier with a "boat in a bottle" structure. Technical Background

[0002] Sustainable low-carbon energy sources such as wind and solar power have received widespread attention globally, sparking research into safe and low-cost electrochemical energy storage systems. Among various studies, zinc-iodine batteries stand out due to their high theoretical specific capacity (211 mAh g⁻¹). -1 ) and a high discharge plateau (1.38 V vs. Zn / Zn) 2+ ), and the abundant reserves of iodine in seawater (55 μg / L). -1 Zinc-iodine batteries are considered one of the most promising candidates due to their abundant reserves of zinc and iodine, coupled with their high energy density (220 Wh / kg). -1 Its characteristics are expected to fill the gap between lithium-ion batteries and lead-acid batteries.

[0003] However, in zinc-iodine batteries, the reversible two-electron redox reaction that occurs at the positive electrode ( The high solubility of polyiodides, intermediate products in zinc-iodine batteries, in water ensures high utilization rates but also leads to a shuttle effect. This shuttle effect results in the loss of active iodine and the generation of numerous byproducts at the negative electrode, which accumulate on the surface, causing zinc interface passivation. Consequently, the cycle capacity of zinc-iodine batteries gradually decreases, and even battery failure occurs. To address this issue, carbon-based materials (graphene, microporous carbon, carbon fibers, etc.) combined with I₂ can mitigate the shuttle effect of polyiodides. However, due to the electrochemical inertness of carbon-based materials, they cannot promote the reaction kinetics of I₂ conversion.

[0004] Therefore, developing a zinc-iodine battery cathode material with excellent conductivity and energy storage properties that can improve one or more of the above problems is of great research significance and application value. Summary of the Invention

[0005] To address the above issues, a novel Ag@porous carbon composite material with a "boat in a bottle" structure is needed to improve the conductivity and storage performance of the positive electrode material in zinc-iodine batteries. This invention provides a method for preparing and applying the Ag@porous carbon composite material with a "boat in a bottle" structure. When applied to the positive electrode of a zinc-iodine battery, this composite material effectively suppresses the shuttle effect of polyiodides, improves the utilization rate of polyiodides, reduces zinc corrosion and the generation of byproducts, enabling the zinc-iodine battery to exhibit higher specific capacity, better rate performance, and better cycle stability.

[0006] To achieve the above objectives, this application provides a zinc-iodine battery positive electrode carrier with a "boat in a bottle" structure. The positive electrode carrier is formed by embedding metallic silver in porous carbon composite material KJ600 to create Ag@KJ600 with a "boat in a bottle" structure.

[0007] This invention also provides a method for preparing Ag@KJ600, an Ag@porous carbon composite material with a ship-in-a-bottle structure. Specifically, it includes the following steps:

[0008] S1. Prepare a 150 μmol / mL silver nitrate solution, add the silver nitrate solution to KJ600, and ultrasonically mix to obtain the precursor of Ag@KJ600 composite material. The ratio of KJ600 to silver nitrate is 25 mg: 154~462 μL, and the preferred ratio is 25 mg: 278 μL.

[0009] S2. Place the Ag@KJ600 precursor obtained in step S1 in a vacuum oven and dry it at 60-80℃; preferably 70℃.

[0010] S3. Place the sample obtained in step S2 into a porcelain boat and fire it in a tube furnace at 500 ℃ for 90 min to obtain Ag@KJ600 powder;

[0011] This application discloses the application of Ag@KJ600, a zinc-iodine battery cathode carrier with a "boat in a bottle" structure, in the cathode of a zinc-iodine battery.

[0012] A zinc-iodine battery cathode material based on the above-mentioned boat-in-a-bottle structure Ag@KJ600 cathode carrier is disclosed, including the zinc-iodine battery cathode material precursor Ag@KJ600 / I2 based on the above-mentioned boat-in-a-bottle structure, a conductive agent, and a binder.

[0013] Furthermore, the method for preparing the zinc-iodine battery cathode material of the present invention includes:

[0014] S4. Grind the Ag@KJ600 powder obtained after calcination in step S3 with I2 together in an argon-protected environment to obtain a fine mixture. The preferred mass ratio of Ag@KJ600:I2 is 2:3.

[0015] S5. The fine mixture obtained in step S4 is heated at 80 °C for 12 h in a sealed environment to obtain the Ag@KJ600 / I2 sample.

[0016] Furthermore, Ag@KJ600 / I2 has a spherical morphology with a relatively uniform particle size of approximately 20-100 nm.

[0017] Furthermore, the conductive agent is selected from one of the following: conductive carbon black (Super P), carbon fiber (VGCF), carbon nanotubes (CNT), or graphene. Super P is preferred.

[0018] Furthermore, the binder is selected from one of polyvinylidene fluoride (PVDF), sodium carboxymethyl cellulose (CMC), or styrene-butadiene rubber (SBR). PVDF is preferred.

[0019] This invention also provides a zinc-iodine battery positive electrode sheet comprising the above-mentioned positive electrode material, including Ag@KJ600 / I2, a conductive agent, and a binder. The zinc-iodine battery positive electrode material precursor Ag@KJ600 / I2 is mixed uniformly with the conductive agent and binder, and finally coated onto a current collector and dried to obtain the electrode sheet as the battery positive electrode sheet. The proportion of Ag@KJ600 / I2 is 60%-80%, the conductive agent is 10%-20%, and the binder is 10%-20%.

[0020] Preferably, the proportion of Ag@KJ600 / I2 is 70%, the conductive agent is 20%, the binder is 10%, and finally it is coated on the current collector and dried to obtain the positive electrode sheet.

[0021] When this electrode is used as the positive electrode of the battery, the zinc-iodine battery can achieve more than 50,000 cycles at a rate of 30 C, with a coulombic efficiency close to 100% and no significant capacity decay, demonstrating excellent electrochemical performance.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] The Ag@porous carbon composite material with a "boat in a bottle" structure of this invention anchors polyiodides to the positive electrode to suppress their migration, and the transition metal Ag fixed on the porous carbon can effectively lower the energy barrier of IRR and improve the I2 / I ratio. – The conversion kinetics, and improve the conversion from I2 to I – The conversion efficiency. These properties enable the Ag@porous carbon composite material with a boat-in-a-bottle structure to significantly improve the electrochemical performance of zinc-iodine batteries.

[0024] When the Ag@KJ600 composite material provided by this invention is used as an iodine cathode carrier in zinc-iodine batteries, this composite material can chemically adsorb polyiodides formed during cycling, suppressing the shuttle effect of polyiodides, thereby reducing zinc corrosion and loss of active materials. This allows the zinc-iodine battery to exhibit higher specific capacity, better rate performance, and better cycle stability. Therefore, this invention has significant value in promoting the industrialization of zinc-iodine batteries.

[0025] The Ag@porous carbon composite material with a "ship-in-a-bottle" structure of this invention possesses the aforementioned superior properties. The mechanism lies in the fact that the silver@porous carbon composite material not only enhances the catalytic activity of silver but also provides the porous carbon material with a larger specific surface area and more active sites. The composite material effectively confines the polyiodides formed by active iodine during cycling, inhibiting the shuttle effect of polyiodides, thereby reducing the loss of active materials and zinc corrosion.

[0026] The cathode material precursor (Ag@KJ600 / I2) was uniformly mixed with a conductive agent and a binder, coated onto a current collector, and dried to obtain the electrode sheet. When this electrode sheet was used as the cathode of a battery, the zinc-iodine battery could achieve more than 50,000 cycles at a rate of 30 C, with a coulombic efficiency close to 100% and no significant capacity decay, exhibiting excellent electrochemical performance. Attached Figure Description

[0027] Figure 1 The XRD pattern of the Ag@KJ600 composite material prepared in Example 1 of this invention compared with the standard card;

[0028] Figure 2 This is a SEM image of the Ag@KJ600 composite material prepared in Example 1 of this invention;

[0029] Figure 3 The image shows an in-situ UV comparison between the Ag@KJ600 composite material prepared in Example 1 and the KJ600 composite material in Comparative Example 1.

[0030] Figure 4 Comparison of the zinc plate of the negative electrode in zinc-iodine batteries after cycling, when the Ag@KJ600 composite material prepared in Example 1 and the KJ600 in Comparative Example 1 are used as positive electrode carriers respectively.

[0031] Figure 5 XPS comparison of Zn2p when Ag@KJ600 composite material prepared in Example 1 and KJ600 in Comparative Example 1 are used as positive electrode supports;

[0032] Figure 6 Rate performance of zinc-iodine batteries when the Ag@KJ600 composite material prepared in Example 1 and the KJ600 in Comparative Example 1 are used as positive electrode carriers.

[0033] Figure 7 The cycling performance of zinc-iodine batteries at 10 C is shown in the graphs of the Ag@KJ600 composite material prepared in Example 1 and the KJ600 in Comparative Example 1, respectively, as positive electrode carriers.

[0034] Figure 8 The graph shows the cycle performance of the zinc-iodine battery at 30 C when the Ag@KJ600 composite material prepared in Example 1 is used as the positive electrode carrier. Detailed Implementation

[0035] The present invention will be further described below through specific embodiments, but these descriptions are not intended to further limit the scope of the invention. Those skilled in the art should understand that equivalent substitutions or corresponding improvements made to the technical features of the present invention still fall within the protection scope of the present invention.

[0036] Unless otherwise specified, the instruments, reagents, and materials used in the following embodiments are all conventional instruments, reagents, and materials already available in the prior art and can be obtained through legitimate commercial channels. Similarly, unless otherwise specified, the experimental methods and detection methods used in the following embodiments are all conventional experimental methods and detection methods already available in the prior art. The KJ600 described in this invention is commercially available and was purchased from Suzhou Shengernuo Technology Co., Ltd. The brand is LION (Japan).

[0037] Example 1

[0038] A silver@porous carbon composite material (Ag@KJ600) and Ag@KJ600 / I2 are prepared as positive electrode carriers for zinc-iodine batteries with a "boat in a bottle" structure.

[0039] (1) Prepare a 150 μmol / mL AgNO3 solution.

[0040] (2) Take 278 μL of AgNO3 solution from step (1) and add it to 25 mg KJ600, and sonicate for 250 min.

[0041] (3) The solution obtained in step (2) was vacuum dried overnight to obtain sample A (Ag@KJ600 precursor).

[0042] (4) The sample A (Ag@KJ600 precursor) dried in step (3) was placed in a tube furnace at 500 °C for 90 min to obtain Ag@KJ600 powder.

[0043] (5) Grind the Ag@KJ600 powder obtained in step (4) with I2 at a mass ratio of 2:3 and obtain a fine mixture in a glove box filled with argon.

[0044] (6) The fine mixture obtained in step (5) is sealed in a Pyrex tube and heated at 80 °C for 12 hours to obtain the Ag@KJ600 / I2 sample.

[0045] Example 2

[0046] Repeat the steps of Example 1, except that the volume of silver nitrate in step (2) is changed to 154 μL.

[0047] Example 3

[0048] Repeat the steps of Example 1, except that the volume of silver nitrate in step (2) is changed to 462 μL.

[0049] Comparative Example 1

[0050] Repeat the steps in Example 1, but change Ag@KJ600 in step (5) to KJ600, and finally obtain the KJ600 / I2 sample.

[0051] Example 4: Preparation of the positive electrode and zinc-iodine battery:

[0052] The composite materials Ag@KJ600 / I2 and KJ600 obtained in Example 1 and Comparative Example 1 were respectively mixed with a conductive agent and a binder at a ratio of 70% Ag@KJ600 / I2, 20% conductive agent, and 10% binder. The mixture was then coated onto a current collector and dried to obtain the positive electrode sheet for a zinc-iodine battery. The conductive agent was Super P; the binder was PVDF. This positive electrode was assembled with a zinc negative electrode, electrolyte, and separator to form a zinc-iodine battery, followed by material characterization and electrochemical testing.

[0053] I. Experimental Objective:

[0054] The composite materials prepared in Example 1 and Comparative Example 1, as well as the zinc-iodine battery containing the composite material, were subjected to performance tests.

[0055] II. Experimental Content and Conclusions:

[0056] The Ag@KJ600 obtained in Example 1 was subjected to X-ray diffraction testing, as shown below. Figure 1 As shown, it matches the standard card PDF#04-0783.

[0057] The Ag@KJ600 obtained in Example 1 was observed under a scanning electron microscope, such as... Figure 2 As shown, the particle size is relatively uniform.

[0058] In-situ UV-Vis absorption spectroscopy was used to study the effect of KJ600 and Ag@KJ600 on I3 during charge and discharge. - The adsorption capacity was observed, such as... Figure 3 As shown, (a) and (b) respectively demonstrate the effects of KJ600 and Ag@KJ600 on I3 during charging and discharging. - The adsorption capacity of KJ600 is shown in the comparison chart, indicating that KJ600 exhibits stronger I3 adsorption capacity than Ag@KJ600. - The absorbance indicates that during the charging process, Ag@KJ600 has a stronger adsorption capacity for polyiodide ions than KJ600, and polyiodide ions are less likely to desorb and dissolve into the electrolyte.

[0059] The cycled zinc anode was cut and observed using confocal ion beam microscopy (FIB), such as... Figure 4 As shown, (a) and (b) present the observation results for KJ600 and Ag@KJ600, respectively. Compared with KJ600, the zinc-iodine battery with Ag@KJ600 composite material as the carrier has a smoother zinc anode surface during cycling, indicating that Ag@KJ600 composite material can suppress the shuttle effect of polyiodide ions, thereby inhibiting the corrosion of zinc anode by polyiodide ions, reducing the generation of by-products, and extending the cycle life of zinc-iodine battery.

[0060] like Figure 5 As shown, Figures (a) and (b) respectively present a comparison of Zn 2p XPS spectra when KJ600 and Ag@KJ600 are used as positive electrode supports. In the Zn 2p XPS spectrum, Ag@KJ600 suppresses the shuttle effect of polyiodides better than KJ600, resulting in less dead zinc formation. Therefore, the peaks of Ag@KJ600 are basically consistent at different depths. However, the peaks of KJ600 gradually decrease with increasing depth. This is because the reaction of polyiodides with zinc produces irreversible byproducts, and the continuous accumulation of these byproducts prevents the reaction of internal zinc. Therefore, Zn 2+ It gradually decreases as the depth increases.

[0061] Figure 6 As shown in the rate performance graph, it can be seen that the specific capacity of Ag@KJ600 at 50 C is higher than that of KJ600 at 20 C. This indicates that Ag@KJ600 has a better inhibition effect on polyiodides than KJ600, and exhibits superior rate performance.

[0062] like Figure 7 The graphs show the cycle stability and coulombic efficiency at a rate of 10 C. Compared with KJ600, when Ag@KJ600 is used as the positive electrode carrier, the zinc-iodine battery has a higher specific capacity and a coulombic efficiency close to 100%, indicating that Ag@KJ600 suppresses the shuttle effect of polyiodide ions to a certain extent.

[0063] Figure 8 The Ag@KJ600 composite material can achieve a higher number of cycles at a rate of 30 C. When the Ag@KJ600 composite material is used as the positive electrode carrier, the zinc-iodine battery can achieve a stable cycle of up to 50,000 cycles without significant capacity decay, demonstrating a good suppression effect of polyiodide ions.

Claims

1. A zinc-iodine battery cathode material, characterized in that, The materials include Ag@KJ600 / I2, a positive electrode material precursor formed by mixing a zinc-iodine battery positive electrode carrier with I2 in a bottle-in-ship structure, a conductive agent, and a binder; The zinc-iodine battery positive electrode carrier with a "boat in a bottle" structure is formed by embedding metallic silver into porous carbon composite material KJ600, creating a silver@porous carbon composite material Ag@KJ600 with a "boat in a bottle" structure. The preparation method of the zinc-iodine battery positive electrode carrier specifically includes the following steps: S1, preparing a 150 μmol / mL silver nitrate solution, adding the silver nitrate solution to KJ600, and ultrasonically mixing to obtain a precursor of the Ag@KJ600 composite material. The ratio of KJ600 to silver nitrate solution is 25 mg: 154~462 μL; S2, drying the Ag@KJ600 composite material precursor obtained in step S1 in a vacuum oven at 60-80℃; S3, placing the sample obtained in step S2 into a ceramic boat and firing it in a tube furnace at 500℃ for 90 min to obtain the silver@porous carbon composite material Ag@KJ600 powder with a "boat in a bottle" structure. The Ag@KJ600 has a spherical morphology with a particle size of 20-100 nm. The battery cathode material precursor Ag@KJ600 / I2 is prepared by the following steps: S4, the silver@porous carbon composite material Ag@KJ600 powder with a ship-in-a-bottle structure obtained in step S3 is ground together with I2 in an argon-protected environment to obtain a fine mixture; S5, the fine mixture obtained in step S4 is heated at 80 ℃ for 12 h in a sealed environment to obtain the battery cathode material precursor Ag@KJ600 / I2.

2. The zinc-iodine battery cathode material according to claim 1, characterized in that, In step S1, the ratio of KJ600 to silver nitrate solution is 25 mg: 278 μL.

3. The zinc-iodine battery cathode material according to claim 1, characterized in that, The drying temperature is 70°C.

4. The zinc-iodine battery cathode material according to claim 1, characterized in that, Step S4 is as follows: the Ag@KJ600 powder obtained after firing in step S3 is ground together with I2 in an argon-protected environment to obtain a fine mixture. The mass ratio of Ag@KJ600 to I2 is 2:

3.

5. The zinc-iodine battery cathode material according to claim 1, characterized in that, The conductive agent is selected from one of conductive carbon black, carbon fiber, carbon nanotubes, or graphene.

6. The zinc-iodine battery cathode material according to claim 4, characterized in that, The adhesive is selected from one of polyvinylidene fluoride, sodium carboxymethyl cellulose, or styrene-butadiene rubber.

7. A positive electrode sheet for a zinc-iodine battery, characterized in that, The preparation method is as follows: Ag@KJ600 / I2, the positive electrode material precursor described in any one of claims 1 to 5, is mixed with a conductive agent and a binder in a mass percentage ratio of 60%-80%:10%-20%:10%-20%, and then coated onto a current collector and dried to obtain a zinc-iodine battery positive electrode sheet.

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