Reversible dendrite-free battery for high voltage and its preparation method and application

Abstract

The application belongs to the technical field of batteries, and particularly relates to a high-voltage reversible dendrite-free battery. The battery comprises a positive electrode, a negative electrode, a separator and an electrolyte, wherein the electrolyte comprises sulfuric acid, manganese sulfate, zinc sulfate and aniline; the positive electrode comprises a positive electrode current collector and a positive electrode active material on the positive electrode current collector, the positive electrode active material being Zn 0.5 MnO2 / PANI; the negative electrode comprises a negative electrode current collector and a negative electrode active material on the negative electrode current collector, the negative electrode active material being Zn 0.5 MnO2 / PANI; the negative electrode comprises a negative electrode current collector and a negative electrode active material on the negative electrode current collector, the negative electrode active material being Zn 0.5 MnO2 / PANI; the negative electrode comprises a negative electrode current collector and a negative electrode active material on the negative electrode current collector, the negative electrode active material being Zn MnO2 is distributed in polyaniline; and Zn-ZIF-8-X means that Zn is deposited on the surface or pores of carbonized ZIF-8, and the carbonized ZIF-8 contains ZnO. The reversible battery has good reversibility, is suitable for high-voltage charging and discharging, and can meet the supply network of fast charging and discharging.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, specifically relating to a reversible, dendrite-free battery for high voltage applications. Background Technology

[0002] The demand for advanced battery technologies with high safety and low cost is growing in the fields of portable electronics, electric vehicles, and renewable energy storage. Although lithium-ion batteries have seen significant improvements in energy / power density and lifespan, safety concerns related to flammable organic electrolytes, as well as increasing worries about the price and availability of lithium resources, hinder the large-scale adoption of lithium-ion batteries. (The last sentence appears to be incomplete and possibly refers to a different topic.) + K + Mg 2+ Zn 2+ Electrochemical insertion / extraction-based battery chemistry in aqueous electrolytes is considered a promising alternative due to its safety, material abundance, and environmental friendliness. Rechargeable zinc-ion batteries (ZIBs) are particularly attractive because zinc exhibits greater aqueous compatibility and stability than alkali metals, allows for multivalent charge transport, and can be produced and reused through established industrial processes.

[0003] Manganese dioxide has a relatively complex crystal structure, which is reflected in its physical structure and chemical composition. Its stoichiometry is not entirely logical; it generally contains small amounts of Mn3O4, Mn2O3, and bound water, so its stoichiometry always indicates a slight oxygen deficiency. MnO is commonly used. X The molecular formula is represented by X, where X represents the oxygen content, which is generally less than 2. MnO2 reacts under acidic conditions to form MnO2 + 4H+. + +2e - →Mn 2+ Since manganese dioxide has a low conductivity (+2H2O), it is often used in neutral or even slightly alkaline dielectric conditions. Because manganese dioxide has very low conductivity, conductive components such as acetylene black or graphite are usually added to ensure electron flow. CN103247781A discloses a manganese dioxide / acetylene black composite material; however, due to the low electrochemical activity of acetylene black and graphite, and the fact that they are only mechanically mixed with manganese dioxide, the pseudocapacitance of manganese dioxide cannot be effectively utilized.

[0004] The conductive polymer PANI possesses advantages such as high conductivity, ease of preparation, good environmental stability, good capacitance performance, and readily available raw materials. Since MnO2 can stably exist under acidic conditions under the protection of a polyaniline (PANI) deposition layer, it not only serves as a suitable deposition layer material for MnO2 under acidic conditions but also inhibits the dissolution of MnO2 in acidic solutions due to reduction. Therefore, forming an MnO2 / PANI electrode can stabilize manganese dioxide in acidic media with high proton concentrations. Metal-organic frameworks (MOFs), also known as porous coordination polymers (PCPs), are synthesized by combining metal ions with organic ligands. The metal ions used to construct MOF structures are typically Zn. 2+ Fe 3+ Ru 2+ Cu 2+ Ni 2+ Pd 2+ Pt 2+ and Co 2+ Organic ligands are generally organic ligands containing carboxyl groups and nitrogen-containing heterocycles. MOFs have well-defined pore structures and extremely high porosity, along with incredibly high specific surface areas, which play a crucial role in functional applications. Therefore, they are widely used in storage and separation, sensing, catalysis, proton conduction, and energy storage devices.

[0005] Although metal-organic rechargeable batteries have significant advantages over traditional rechargeable batteries, they have not yet achieved industrial-scale production, mainly due to the following reasons: First, prolonged immersion of metal electrodes in electrolyte can lead to corrosion and passivation, or the formation of dendrites during charging and discharging, which can puncture the separator and cause a short circuit. Second, organic materials (such as polyaniline) can detach from the current collector during charging and discharging, resulting in an open circuit. Third, polyaniline degrades during charging and discharging, causing a rapid decrease in battery capacity and shortening the battery's cycle life. These factors compromise the battery's coulombic efficiency and cycle life, thus hindering the further development and application of metal-organic rechargeable batteries. Summary of the Invention

[0006] To address the problems existing in the prior art, the present invention provides a reversible dendrite-free battery for high voltage applications.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] In a first aspect, the present invention provides a reversible battery, the battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the electrolyte comprises sulfuric acid, manganese sulfate, zinc sulfate, and aniline; the positive electrode comprises a positive electrode current collector and a positive electrode active material located on the positive electrode current collector, the positive electrode active material being Zn. 0.5MnO2 / PANI; the negative electrode includes a negative electrode current collector and a negative electrode active material located on the negative electrode current collector, wherein the negative electrode active material is Zn-ZIF-8-X, wherein Zn 0.5 MnO2 / PANI refers to Zn 0.5 MnO2 is distributed in polyaniline; Zn-ZIF-8-X refers to Zn deposited on the surface or in the pores of carbonized ZIF-8 and ZnO contained in the carbonized ZIF-8.

[0009] The ZIF-8 of this invention, namely zeolite imidazole ester framework material, is a porous crystalline material formed by the coordination and self-assembly of zinc ions and 2-methylimidazolium, which has the characteristics of large specific surface area and high porosity.

[0010] In the above-mentioned reversible battery, as a preferred embodiment, the negative electrode current collector is nickel foam.

[0011] In the above-mentioned reversible battery, as a preferred embodiment, the positive electrode current collector is carbon cloth.

[0012] In the above-mentioned reversible battery, as a preferred embodiment, the carbonized ZIF-8 is obtained by heat-treating ZIF-8 at 450-550°C.

[0013] Secondly, the present invention provides a method for preparing the above-mentioned reversible battery, the method comprising the following steps in sequence:

[0014] S1. ZIF-8 is heat-treated to obtain ZIF-8-X, and ZIF-8-X is coated on the negative electrode current collector;

[0015] S2. Assemble the positive current collector without positive electrode active material, the negative current collector loaded with ZIF-8-X in step S1, the separator, and the electrolyte into a battery.

[0016] S3. The battery assembled in step S2 is subjected to constant voltage deposition to obtain the reversible battery.

[0017] During the constant-pressure deposition process, Zn is generated on the positive current collector of the reversible battery. 0.5 Zn-ZIF-8-X is generated on the negative electrode current collector of the reversible battery using MnO2 / PANI.

[0018] In this invention, a battery is assembled using a positive current collector without a positive electrode active material, a negative current collector loaded with ZIF-8-X, a separator, and an electrode solution. Then, Zn is generated on the positive and negative current collectors respectively by constant voltage deposition. 0.5MnO2 / PANI and Zn-ZIF-8-X. Compared with CF3SO3 salts, ZnSO4 and MnSO4 solutes have lower cost, better stability, and higher solubility in water. Depositing zinc on ZIF-8-X to form Zn-ZIF-8-X instead of the traditional compact zinc foil anode can suppress zinc dendrites and improve zinc utilization and the corresponding total energy / power density.

[0019] In the above-described method for preparing a reversible battery, as a preferred embodiment, step S1, the method for preparing ZIF-8 sequentially includes the following steps:

[0020] Sa, zinc nitrate and 2-methylimidazole were dissolved in solvents respectively, then mixed and aged to obtain a mixed solution;

[0021] Sb, Centrifuge the mixed solution obtained in step Sa and collect the precipitate;

[0022] Sc. Wash the precipitate collected in step Sb with solvent, and then dry the precipitate to obtain ZIF-8.

[0023] In the above-mentioned method for preparing reversible batteries, as a preferred embodiment, in step Sa, the solvent is methanol, deionized water, or ammonia.

[0024] In the above-mentioned method for preparing reversible batteries, as a preferred embodiment, in step Sa, the molar ratio of zinc nitrate to 2-methylimidazole is 1:(3.8~4.2) (e.g. 1:3.9, 1:4.0, 1:4.1).

[0025] In the above-mentioned method for preparing reversible batteries, as a preferred embodiment, in step Sa, the aging time is 10 to 24 hours (e.g., 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h).

[0026] In the above-mentioned method for preparing reversible batteries, as a preferred embodiment, in step Sc, the solvent is methanol; preferably, the drying temperature is 60~80℃ (e.g., 65℃, 70℃, 75℃).

[0027] In the above-mentioned method for preparing reversible batteries, as a preferred embodiment, in step S1, X in ZIF-8-X is the heat treatment temperature of ZIF-8, in degrees Celsius, and 450≤X≤550.

[0028] In the above-described method for preparing a reversible battery, as a preferred embodiment, in step S1, the loading of ZIF-8-X on the negative electrode current collector is 1.2~1.8 mg / cm³. 2(e.g., 1.3 mg / cm) 2 1.4 mg / cm 2 1.5 mg / cm 2 1.6 mg / cm 2 1.7 mg / cm 2 ).

[0029] In the above-mentioned method for preparing reversible batteries, as a preferred embodiment, in step S1, the heat treatment is carried out at a heating rate of 2~4℃ / min (e.g., 2.25℃ / min, 2.5℃ / min, 2.75℃ / min, 3℃ / min, 3.25℃ / min, 3.5℃ / min, 3.75℃ / min) to the holding temperature.

[0030] In the above-mentioned method for preparing reversible batteries, as a preferred embodiment, in step S1, the heat treatment holding time is 2 to 4 hours (e.g., 2.25 hours, 2.5 hours, 2.75 hours, 3 hours, 3.25 hours, 3.5 hours, 3.75 hours).

[0031] In the above-described method for preparing reversible batteries, as a preferred embodiment, in step S1, the heat treatment is carried out in an inert atmosphere; preferably, the heat treatment is carried out in a tube furnace.

[0032] In the above-described method for preparing a reversible battery, as a preferred embodiment, in step S2, the electrolyte comprises: sulfuric acid, manganese sulfate, zinc sulfate, and aniline; preferably, the solvent of the electrolyte is deionized water; preferably, the electrolyte comprises: 0.08~0.12M (e.g., 0.09M, 0.1M, 0.11M) of H2SO4, 0.8~1.2M (e.g., 0.09M, 0.1M, 0.11M) of MnSO4, 0.08~0.12M (e.g., 0.09M, 0.1M, 0.11M) of aniline, and 0.8~1.2M (e.g., 0.09M, 0.1M, 0.11M) of ZnSO4; preferably, the electrolyte comprises: 0.1M of H2SO4, 1M of MnSO4, 0.1M of aniline, and 1M of ZnSO4.

[0033] In the above-mentioned method for preparing reversible batteries, as a preferred embodiment, in step S2, the positive electrode current collector is carbon fiber cloth.

[0034] In the above-mentioned method for preparing reversible batteries, as a preferred embodiment, in step S2, the negative electrode current collector is nickel foam.

[0035] In the above-described method for preparing a reversible battery, as a preferred embodiment, the constant-voltage deposition conditions in step S3 are as follows: the battery assembled in step S2 is charged at a constant voltage of 2.0~2.4V (e.g., 2.1V, 2.2V, 2.3V) until the capacity reaches 1.8~2.2 mAh / cm³. 2 (e.g., 1.9mAh / cm) 2 2.0mAh / cm 2 2.1mAh / cm 2 ).

[0036] In the above-mentioned method for preparing reversible batteries, as a preferred embodiment, in step S3, the battery assembled in step S2 is left to stand for 20 to 30 hours (e.g., 21 hours, 22 hours, 23 hours, 24 hours, 25 hours, 26 hours, 27 hours, 28 hours, 29 hours) before constant pressure deposition is performed.

[0037] Thirdly, the present invention provides a reversible battery prepared by the preparation method described in the second aspect above.

[0038] Compared with the prior art, the present invention has at least the following beneficial effects:

[0039] 1. The ZIF-8-X prepared by this invention is obtained by heat treatment of ZIF-8 to obtain carbonized ZIF-8, namely ZIF-8-X. The obtained ZIF-8-X has trace amounts of ZnO generated in its framework, and has a high overpotential to prevent hydrogen evolution and reduce water decomposition. It effectively prevents dendrite growth during cycling, thus making its cycle reversibility much higher than that of other electrodes.

[0040] 2. Electrodeposition of Zn 0.5 MnO2 / PANI composite material is used as the positive electrode active material. Electrochemical test results show that the electrochemical reaction of the battery is diffusion-controlled. Compared with the operating voltage of traditional alkaline zinc-manganese batteries (0.6~1.5 V), the discharge voltage of this battery is 0.8~2 V, which is about 50% higher. The reversible battery of this invention can achieve an areal capacity of up to 5 mAh / cm². 2 With a charging / discharging efficiency of 96.0%, it can meet the needs of a fast charging / discharging power supply network. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the Zn-MnO2 / PANI battery assembly in Example 1.

[0042] In Figure 2, (a) the SEM detection results of ZIF-8-500 in detection example 1;

[0043] (b) Enlarged view of the SEM detection results of ZIF-8-500 in Detection Example 1;

[0044] (c) XRD patterns of ZIF-8 and ZIF-8-500 in Example 1;

[0045] (d) Results of electrochemical performance testing of the reversible battery prepared in Example 1 in Example 2;

[0046] (e) The positive electrode materials of the reversible batteries prepared in Example 1 and Comparative Example 1 in Example 3 (which were respectively deposited with Zn) were tested. 0.5 MnO2 / PANI or Zn 0.5 XRD results of carbon cloth containing MnO2;

[0047] (f) Test the reversible battery cathode material (with Zn deposited) prepared in Comparative Example 1 in Example 3. 0.5 SEM images of carbon cloth containing MnO2;

[0048] (g) corresponds to the EDS characterization of Mn element in the sample detected in Figure 2(f);

[0049] (h) corresponds to the EDS characterization of the O element in the sample tested in Figure 2(f);

[0050] (i) The reversible battery cathode material prepared in Example 1 of Example 3 (with Zn deposited) was tested. 0.5 SEM images of carbon cloth (MnO2 / PANI);

[0051] (j) corresponds to the EDS characterization of C element in the sample tested in Figure 2(i);

[0052] (k) corresponds to the N element EDS characterization of the sample in Figure 2(i);

[0053] (l) corresponds to the EDS characterization of the O element in the sample tested in Figure 2(i);

[0054] (m) corresponds to the EDS characterization of the Mn element in the sample detected in Figure 2(i).

[0055] Figure 3(a) shows the electrochemical performance test results of the reversible battery prepared in Example 1 of Example 4.

[0056] (b) The pH value of the electrolyte in the reversible battery prepared in Example 1 of Test Example 5 during the cycling process;

[0057] (c) Results of electrochemical performance testing of the reversible battery prepared in Example 1 of Example 6;

[0058] (d) Capacity change curve of the reversible battery prepared in Example 1 of Example 7 during 200 cycles;

[0059] (e) Comparison of EIS after discharge in the first cycle and after discharge in the 200th cycle of the reversible battery prepared in Example 1 of Example 7 during 200 cycles.

[0060] In Figure 4, (a) is a comparison of the discharge curves of the reversible batteries prepared in Example 1 and Comparative Example 1 in Example 8;

[0061] (b) Comparison of AC impedance of reversible batteries prepared in Example 1 and Comparative Example 1 in Example 9;

[0062] (c) Test results of the cycle performance of the reversible batteries prepared in Example 1 and Comparative Example 1 in Test Example 10;

[0063] (d) The electrochemical performance test results of the reversible battery prepared in Example 1 of Example 11.

[0064] Figure 5 The results are for testing the cycle performance of the reversible batteries prepared in Example 1 of Example 13 and Comparative Examples 2-4. Detailed Implementation

[0065] This invention synthesizes a Zn by a one-step electrodeposition method. 0.5 MnO2 / PANI composite material was used as the positive electrode active material, and Zn-ZIF-8-X as the negative electrode active material. Electrochemical experiments showed that both materials exhibited excellent rechargeability. In high-voltage electrolytic zinc-ion batteries, MnO2 was excited... 4+ / Mn 2+ The unique two-electron redox electrolysis reaction has a theoretical voltage of 2 V. The reversible battery provided by this invention has a high discharge plateau at 2 V and stability for 200 long-term cycles.

[0066] Zn was prepared by constant voltage deposition method 0.5 MnO2 / PANI composite material, wherein Zn 0.5 The synthesis of MnO2 mainly includes the following four processes:

[0067] Mn 2+ +2H₂O → MnO₂ + 4H₂O + +2e - (1)

[0068] MnO2 + 4H + +2e - Mn 2+ +2H2O (2)

[0069] MnO2+H + +e - MnOOH(3)

[0070] MnO2+ 0.5Zn 2+ + e – Zn 0.5 MnO2(4)

[0071] In a preferred embodiment of the present invention, the composite material Zn is composed of MnO2, PANI, and Zn. 0.5 MnO2 / PANI is synthesized via electrodeposition using a constant voltage technique. Battery assembly: Carbon cloth without positive electrode active material is used as the positive electrode, and ZIF-8-X-coated nickel foam is used as the negative electrode. The positive and negative electrodes are separated by a separator, and the battery is assembled. It is then immersed in the electrolyte for 24 hours to ensure the electrolyte fully wets the separator and ZIF-8-X. The electrolyte includes H2SO4, MnSO4, ZnSO4, and ANI.

[0072] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Those skilled in the art should understand that the embodiments described are merely illustrative of the invention and should not be considered as specific limitations thereof. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0073] The embodiments of the present invention are implemented under the premise of the technical solution of the present invention, and detailed implementation methods and processes are given. However, the protection scope of the present invention is not limited to the following embodiments. The process parameters in the following embodiments that do not specify specific conditions are generally in accordance with conventional conditions.

[0074] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0075] In this invention, unless otherwise specified and / or stated, all values ​​relating to component amounts are in parts by weight throughout. Process parameters in the following examples that do not specify particular conditions are generally performed under conventional conditions.

[0076] Example 1

[0077] (1) Preparation of ZIF-8: Zinc nitrate hexahydrate (2.975 g, Ar) and 2-methylimidazole (3.284 g, Ar) were dissolved in methanol (100 mL, Ar) respectively, mixed for 5 minutes under vigorous stirring, and then the resulting solution was aged at room temperature for 12 hours to obtain a mixed solution. The mixed solution was centrifuged and the precipitate (white powder) was collected, washed 3 times with methanol, and dried overnight at 80 °C to obtain ZIF-8 nanocrystals.

[0078] (2) The ZIF-8 nanocrystals synthesized in step (1) were kept at a high temperature of 500℃: ZIF-8 was placed in a tube furnace and heated to 500℃ at a heating rate of 3℃ / min. The temperature was kept at 3h under a nitrogen atmosphere to obtain ZIF-8-500 (the ZIF-8 skeleton after burning has a trace amount of ZnO generated, and has a high overpotential that can prevent hydrogen evolution and reduce water decomposition, and effectively prevent dendrite growth during cycling).

[0079] (3) The method of assembling the battery is as follows Figure 1 As shown, Figure 1 In the diagram, 1 is the positive electrode shell, 2 is hollow carbon cloth (thickness 0.25 mm, porosity 77%), 3 is the separator (glass fiber separator), and 4 is nickel foam loaded with ZIF-8-500 (porosity: 96.5%, thickness 1.6 mm, ZIF-8-500 loading on the nickel foam is 1.5 mg / cm³). 2 ), 5 is the negative electrode shell, and the battery model is CR2032. The electrolyte is 0.1 M H2SO4, 1 M MnSO4, 1 M ZnSO4, and 0.1 M aniline, and the solvent is deionized water. After assembly, it was left to stand at room temperature for 24 hours.

[0080] (4) The battery assembled in step (3) is deposited at a constant voltage of 2.2 V until the termination condition: capacity of 2 mAh / cm³. 2 The reversible battery was fabricated in 90 seconds.

[0081] Zn is deposited on the positive electrode carbon cloth after deposition. 0.5 MnO2 / PANI, Zn-ZIF-8-X is deposited on the negative electrode.

[0082] During constant-pressure deposition, Zn in the electrolyte solution 2+ Mn 2+ Aniline and aniline are reduced to Zn at the negative electrode, and then oxidized on carbon cloth to form solid Zn. 0.5MnO2 and polyaniline. Traditional battery electrode materials are typically fabricated by first preparing active materials chemically, then adding binders (such as PTFE) and solvents, grinding, and finally coating them onto the current collector. However, in most cases, the binder only enhances mechanical strength and adhesion, contributing nothing to the conductivity or capacity of the electrode material; in fact, it increases the material's internal resistance. This invention uses direct in-situ deposition of electrode materials onto the current collector, eliminating the need for any binders and effectively controlling the morphology and thickness of the deposited material.

[0083] Comparative Example 1

[0084] This comparative example is basically the same as Example 1, except that the electrolyte used in step (3) in this comparative example is 0.1 M H2SO4, 1 M MnSO4 and 1 M ZnSO4.

[0085] In this comparative example, the reversible battery prepared has Zn as the active material deposited on the positive electrode. 0.5 The active material obtained by depositing MnO2 on the negative electrode is Zn-ZIF-8-X.

[0086] Comparative Example 2

[0087] This comparative example is basically the same as Example 1, except that in this comparative example, the heat treatment temperature of ZIF-8 nanocrystals in step (2) is 400℃.

[0088] Comparative Example 3

[0089] This comparative example is basically the same as Example 1, except that in this comparative example, the heat treatment temperature of ZIF-8 nanocrystals in step (2) is 600℃.

[0090] Comparative Example 4

[0091] This comparative example is basically the same as Example 1, except that in this comparative example, the heat treatment temperature of ZIF-8 nanocrystals in step (2) is 800℃.

[0092] The detection results of detection example 13 are as follows: Figure 5 As shown, in Example 1, when the heat treatment temperature of ZIF-8 nanocrystals was 500℃, the prepared reversible battery exhibited the highest coulombic efficiency of 99.6%, and its reversibility was far superior to that of other electrodes. It remained stable during cycling without any significant decrease.

[0093] The reversible battery prepared in Comparative Example 2 (when the heat treatment temperature of ZIF-8 nanocrystals was 400℃) had low reversibility, which was due to the lack of ZnO distribution in the framework of ZIF-8-400 prepared in Comparative Example 2.

[0094] In the reversible batteries prepared in Comparative Examples 3 and 4, the heat treatment temperature for ZIF-8 nanocrystals was too high (600℃ and 800℃, respectively). As a result, N-doped carbon (with hydrogen catalytic activity) was formed in ZIF-8-600 and ZIF-8-800 after heat treatment, leading to the decomposition of H2O and thus affecting the reversibility of the battery.

[0095] Example of detection:

[0096] Example 1. XRD detection was performed on the ZIF-8 nanocrystals prepared in step (1) of Example 1, and SEM and XRD detection were performed on the ZIF-8-500 obtained in step (2) of Example 1. The results are shown in Figure 2.

[0097] Figure 2(a) shows the structure of ZIF-8-500 as a scanning electron microscope image, and Figure 2(b) is an enlarged view of Figure 2(a);

[0098] Figure 2(c) shows the XRD patterns of ZIF-8 and ZIF-8-500.

[0099] Comparing the test curve of ZIF-8 in Figure 2(c) with the simulated curve of standard ZIF-8 crystal shows that ZIF-8 crystal was effectively synthesized in this embodiment. After carbonization (heat treatment), the characteristic peaks of ZIF-8 no longer exist in ZIF-8-500, and instead, broad peaks corresponding to amorphous carbon are present, indicating that the carbonization process of ZIF-8-500 after heat treatment is complete.

[0100] As shown in the XRD pattern of Figure 2(c), the diffraction peaks of ZIF-8 are relatively sharp, indicating that ZIF-8 has a high degree of crystallinity. The XRD pattern of ZIF-8-500 shows a broad diffraction peak at approximately 25°, which is a characteristic peak of amorphous carbon materials, and a less obvious diffraction peak at 44°, which is a characteristic peak of graphite. This indicates that the nitrogen-doped derived porous carbon obtained after carbonization of ZIF-8 at 500℃ has a certain degree of graphitization.

[0101] Example 2. The electrochemical performance of the reversible battery prepared in Example 1 was tested under the following conditions: the test was conducted within a voltage range of 0.8 to 2V, and the charging condition was constant voltage charging at 2.2V to 2.0mAh × cm⁻¹. -2 , at 4mA / cm 2 The discharge is carried out under the current conditions until the cutoff voltage is reached. The discharge curves for the first six cycles are shown in Figure 2(d).

[0102] As shown in Figure 2(d), the discharge capacity in the first cycle (1st) is 1.3 mAh / cm³. -2The initial coulombic efficiency (CE) was 60%. In the 6th cycle (6th), the discharge capacity increased to 1.89 mAh / cm³. -2 It can be clearly seen that the discharge curve slope of these six cycles has two abrupt changes. Based on these two abrupt changes, the discharge curve can be divided into three discharge regions: D1 (2.0~1.8 V), D2 (1.8~1.05 V), and D3 (1.05~0.8 V). Among them, the capacity of the D1 region increases with the increase of the cycle, which is the main reason for the high total capacity of the reversible battery prepared by this invention and its applicability to high voltage.

[0103] Example 3. Positive electrode materials of the reversible batteries prepared in Example 1 and Comparative Example 1 (each having Zn deposited on it) were taken respectively. 0.5 MnO2 / PANI or Zn 0.5 The carbon cloth containing MnO2 was subjected to XRD detection, and the detection results are shown in Figure 2(e).

[0104] In Figure 2(e), the reversible battery cathode material prepared in Example 1 (with Zn deposited) 0.5 The XRD pattern of the carbon cloth (MnO2 / PANI) shows that 2θ=16°, 20° and 25° are the characteristic peaks of the emerald green imine state of PANI, corresponding to the (001), (020) and (200) crystal planes, respectively. Among them, the diffraction peaks of 2θ=16° and 25° are related to the periodic structure perpendicular and parallel to the polymer backbone, and the diffraction peak of 2θ=20° is caused by the alternation of polymer chains. The peak broadening indicates that the obtained PANI has an amorphous structure.

[0105] MnO2 (JCPDS #30-0820) has typical peaks at (100) and (101), with angles of 37.1° and 42.4°, respectively. These weak and broad peaks are related to its nanoscale polycrystalline structure.

[0106] In Figure 2(e), the reversible battery cathode material prepared in Comparative Example 1 (with Zn deposited) 0.5 The XRD pattern of the carbon cloth containing MnO2 shows two sharp peaks at 2θ = 26.60° and 54.79°, which are characteristic peaks of the carbon cloth. No obvious MnO2 diffraction peaks are observed in the XRD pattern. This is partly because the loading of MnO2 on the carbon cloth is low, and most of the characteristic diffraction peaks of manganese dioxide are masked by the strong peaks of the carbon cloth. On the other hand, it also indicates that the manganese dioxide obtained by the electrochemical deposition method has poor crystallinity.

[0107] The reversible battery cathode materials prepared in Example 1 and Comparative Example 1 (which were respectively deposited with Zn) were taken respectively. 0.5 MnO2 / PANI or Zn 0.5The carbon cloth containing MnO2 was subjected to SEM-EDS detection, and the detection results are shown in Figure 2(f), Figure 2(g), Figure 2(h), Figure 2(j), Figure 2(k), Figure 2(l), and Figure 2(m).

[0108] Figure 2(f) shows the reversible battery cathode material prepared in Comparative Example 1 (with Zn deposited). 0.5 SEM images of carbon cloth with MnO2, Figure 2(g) and Figure 2(h) correspond to the EDS characterization of Mn and O elements in the sample in Figure 2(f).

[0109] Figure 2(i) shows the reversible battery cathode material (with Zn deposited) prepared in Example 1. 0.5 SEM images of carbon cloth (MnO2 / PANI), Figures 2(j), 2(k), 2(l), and 2(m) correspond to the EDS characterization of C, N, O, and Mn elements in the sample in Figure 2(i), respectively. These images show the influence of C, N, O, and Mn elements on Zn. 0.5 The MnO2 / PANI is uniformly distributed, indicating that MnO2 and PANI are very uniformly combined, and the composite material was successfully prepared.

[0110] In Figure 2(f), the reversible battery cathode material (with Zn deposited) prepared from Comparative Example 1 is shown. 0.5 The SEM image of the carbon cloth (MnO2) shows that, under high magnification, the sediment (Zn) can be clearly observed. 0.5 MnO2 exhibits a porous, plate-like structure, which facilitates electrolyte wetting and allows Zn to... 0.5 The MnO2 active sites are in full contact with the electrolyte, improving the activity of the electrode material (ZnO2). 0.5 The utilization rate of MnO2 is beneficial to the active material (ZnO2) of the electrode material. 0.5 The electrochemical properties of MnO2 are brought into play.

[0111] In Figure 2(i), the reversible battery cathode material (with Zn deposited) prepared from Example 1 is shown. 0.5 The SEM image of the MnO2 / PANI carbon cloth shows that MnO2 is located on the PANI surface, and ZnO2 is arranged in a cauliflower-like pattern. 0.5 The PANI / MnO2 fiber network structure becomes smaller, and the particles are significantly refined.

[0112] Example 4. The electrochemical performance of the reversible battery prepared in Example 1 was tested under the following conditions: the test was conducted within a voltage range of 0.8 to 2V, and the charging condition was constant voltage charging at 2.2V to 2.0mAh × cm⁻¹. -2 Then, 2mA×cm were used respectively. -2 4mA×cm -2 8mA×cm -215mA×cm -2 or 30mA×cm -2 Constant current discharge was performed, and the results are shown in Figure 3(a).

[0113] High-rate charge and discharge capability is considered a key indicator for the large-scale application of batteries, such as fast charging of electric vehicles and mobile phones, as well as regenerative braking. The zinc battery discharge curve in Figure 3(a) exhibits typical battery behavior characteristics at 2 mA cm⁻¹. -2 The discharge voltage is 2.05 V at 30 mA cm⁻¹. -2 The discharge voltage is 1.6V (100 s), which enables rapid charging and discharging under high voltage.

[0114] Example 5. The pH value of the electrolyte in the reversible battery prepared in Example 1 was measured using a pH meter during cycling. Cycling conditions: voltage 0.8~2.2V; current 4 mA / cm². 2 The constant current charge-discharge cycle was performed, and the results are shown in Figure 3(b).

[0115] Throughout the entire cycle, the electrolyte pH of the reversible battery remains at 1, and the discharge plateau and electrolyte pH value remain stable.

[0116] Example 6. The electrochemical performance of the reversible battery prepared in Example 1 was tested under the following cycling conditions: voltage 0.8~2.2V, and 2.0 mA / cm². 2 Constant current charging, 2 mA / cm² for the first 5 cycles. 2 Constant current discharge, 4mA / cm for cycles 6-10. 2 Constant current discharge, 8mA / cm for cycles 11-15. 2 Constant current discharge, 15mA / cm for cycles 16-20. 2 Constant current discharge, 30mA / cm for cycles 21-25. 2 Constant current discharge, 4mA / cm for cycles 26-30. 2 Constant current discharge was performed, and the results are shown in Figure 3(c). A constant current discharge of 2 mA / cm² was used. 2 The discharge capacity during discharge is greater than 1.9 mAh / cm³. 2 Using 30 mA / cm 2 During discharge, the discharge capacity is greater than 1.4 mAh / cm³. 2 .

[0117] Example 7. The electrochemical performance of the reversible battery prepared in Example 1 was tested under the following cycling conditions: voltage 0.8~2.2V, at 4 mA / cm². 2 The current density was used to test the stability of charge-discharge cycles and to detect its internal resistance.

[0118] The instrument used to test internal resistance is a multimeter.

[0119] The capacity change curve of the battery is shown in Figure 3(d). The reversible battery prepared in Example 1 of this invention exhibits good cycle sustainability at 4 mA / cm². 2 After 200 charge-discharge cycles at the specified rate, the battery retains nearly 90% of its capacity.

[0120] Figure 3(e) shows a comparison of the EIS after the first discharge cycle and the second discharge cycle in a 200-cycle reversible battery. The resistance increases after cycling, and the capacity gradually decreases after 200 cycles (Figure 3(d) shows a 10% capacity decrease after 200 cycles), which can be attributed to the increased resistance after cycling. Importantly, this demonstrates that the excellent rate stability of the reversible battery prepared in Example 1 of this invention is not accidental, but rather due to its stable electrolysis reaction, higher electrolyte conductivity, lower ohmic and charge transfer resistance, and faster ion diffusion rate.

[0121] Example 8. The cycle performance of the reversible batteries prepared in Example 1 and Comparative Example 1 was tested under the following conditions: voltage 0.8~2.2V, at 4 mA / cm². 2 The current density was used for charging and discharging, and the test results are shown in Figure 4(a).

[0122] As shown in Figure 4(a), when the active material deposited on the positive electrode is Zn 0.5 When using MnO2, it is evident that the discharge plateau is only 1.5 V, and there is a significant capacity loss. However, the active material deposited on the positive electrode is Zn. 0.5 PANI / MnO2 composites exhibit a discharge plateau of nearly 2 V with almost no capacity loss.

[0123] Example 9. The reversible batteries prepared in Example 1 and Comparative Example 1 were subjected to AC impedance testing using an electrochemical workstation. Testing conditions: Frequency range: 10... -2 ~10 6 The detection result is shown in Figure 4(b).

[0124] Figure 4(b) shows that the cathode material is Zn. 0.5 MnO2 and Zn are the cathode materials. 0.5 Impedance spectrum of the PANI / MnO2 composite cell.

[0125] The size of the semi-circular diameter in the high-frequency region reflects the speed of charge transfer in the material. As can be seen from the figure, the cathode material is Zn. 0.5The PANI / MnO2 composite material exhibits a small arc radius in the high-frequency region, indicating low charge transfer resistance and a fast charge transfer rate, thus demonstrating good conductivity. Both cathode materials show approximately linear curves in the low-frequency region. The slope of these curves in the low-frequency region indicates the rate of ion diffusion and mass transfer at the electrode surface; a larger slope indicates faster ion diffusion. Figure 4(b) shows that Zn... 0.5 The large slope of the PANI / MnO2 composite material indicates that the ions in Zn 0.5 The PANI / MnO2 composite electrode surface exhibits rapid mass transfer.

[0126] The above results indicate that Zn 0.5 PANI / MnO2 composite electrode materials not only have a fast charge transfer rate but also a fast ion transport rate, and therefore should also have good capacitance properties.

[0127] Test Example 10. The reversible batteries prepared in Example 1 and Comparative Example 1 were subjected to cycle performance testing under the following conditions: voltage 0.8~2.2V, at 4 mA / cm². 2 The current density was used to test the stability of charge-discharge cycles, and the test results are shown in 4(c).

[0128] Figure 4(c) shows that the cathode material is Zn. 0.5 MnO2 and Zn are the cathode materials. 0.5 Coulombic efficiency plot of a reversible battery using PANI / MnO2 composite material after 200 cycles, with Zn as the cathode material. 0.5 The coulombic efficiency (the ratio of battery discharge capacity to charge capacity during the same cycle) of the PANI / MnO2 composite reversible battery is almost 100% (the decrease at cycle 180 is attributed to detection error). In Comparative Example 1, the cathode material is Zn. 0.5 The reversible battery of MnO2 has a coulombic efficiency of 90% after 200 cycles.

[0129] Example 11. The electrochemical performance of the reversible battery prepared in Example 1 of this invention was tested under the following conditions: voltage 0.8~2.2V, and charging condition: constant voltage of 2.2V to 2.0mAh×cm. -2 3.0mAh×cm -2 4.0mAh×cm -2 Or 5.0mAh×cm -2 Discharge conditions: at 4 mA / cm 2 The constant current discharge test results are shown in Figure 4(d). The reversible battery prepared in Example 1 of this invention can simultaneously maintain an areal capacity (based on the area of ​​the positive electrode current collector) of up to 5 mAh cm⁻¹. -2The battery was charged / discharged with a coulombic efficiency of 96.0%. This demonstrates the potential for large-scale application of the reversible battery prepared in this invention.

[0130] Example 12. Three reversible batteries prepared in Example 1 of this invention were connected in series to form a battery pack, which successfully charged a standard mobile phone battery (5V, 5W) for 20 seconds. A redox flow battery pack model was established using the reversible battery prepared in Example 1, verifying the feasibility of using a novel electrolytic zinc battery (the reversible battery prepared in Example 1) to achieve large-scale energy storage. This is very important for meeting the rapid power changes in practical power grid applications.

[0131] Example 13. The reversible batteries prepared in Example 1 and Comparative Examples 2-4 of the present invention were cycled under the following conditions: voltage 0.8~2.2V; current 4 mA / cm². 2 The coulombic efficiency during the cyclic process was tested, and the results are as follows: Figure 5 As shown.

[0132] In Example 1, when the heat treatment temperature of ZIF-8 nanocrystals was 500℃, the prepared reversible battery exhibited the highest coulombic efficiency of 99.6%, and its reversibility was far superior to that of other electrodes. It remained stable during cycling without any significant decrease.

[0133] The reversible battery prepared in Comparative Example 2 (when the heat treatment temperature of ZIF-8 nanocrystals was 400℃) had low reversibility, which was due to the lack of ZnO distribution in the framework of ZIF-8-400 prepared in Comparative Example 2.

[0134] In the reversible batteries prepared in Comparative Examples 3 and 4, the excessively high holding temperatures (600℃ and 800℃, respectively) during the heat treatment of ZIF-8 nanocrystals led to the formation of N-doped carbon (with hydrogen catalytic activity) in the resulting ZIF-8-600 and ZIF-8-800, causing H2O decomposition and thus affecting the battery's reversibility. In summary, the reversible battery prepared in this invention exhibits excellent reversibility and cycle efficiency.

[0135] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. However, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A reversible battery, characterized in that, The battery includes a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the electrolyte includes sulfuric acid, manganese sulfate, zinc sulfate, and aniline; the positive electrode includes a positive electrode current collector and a positive electrode active material located on the positive electrode current collector, wherein the positive electrode active material is Zn. 0.5 MnO2 / PANI; the negative electrode includes a negative electrode current collector and a negative electrode active material located on the negative electrode current collector, wherein the negative electrode active material is Zn-ZIF-8-X, wherein Zn 0.5 MnO2 / PANI refers to Zn 0.5 MnO2 is distributed in polyaniline; Zn-ZIF-8-X refers to Zn deposited on the surface or in the pores of carbonized ZIF-8 and ZnO contained in the carbonized ZIF-8. The negative electrode current collector is nickel foam; The positive electrode current collector is carbon cloth; The method for preparing the reversible battery includes the following steps in sequence: S1. ZIF-8 is heat-treated at 450-550℃ to obtain ZIF-8-X, and ZIF-8-X is coated on the negative electrode current collector. S2. Assemble the positive current collector without positive electrode active material, the negative current collector loaded with ZIF-8-X in step S1, the separator, and the electrolyte into a battery. S3. The battery assembled in step S2 is subjected to constant voltage deposition to obtain the reversible battery. During the constant-pressure deposition process, Zn is generated on the positive current collector of the reversible battery. 0.5 Zn-ZIF-8-X is generated on the negative electrode current collector of the reversible battery using MnO2 / PANI.

2. The reversible battery as described in claim 1, characterized in that, In step S1, the preparation method of ZIF-8 includes the following steps in sequence: Sa, zinc nitrate and 2-methylimidazole were dissolved in solvents respectively, then mixed and aged to obtain a mixed solution; Sb, Centrifuge the mixed solution obtained in step Sa and collect the precipitate; Sc. Wash the precipitate collected in step Sb with solvent, and then dry the precipitate to obtain ZIF-8.

3. The reversible battery as described in claim 2, characterized in that, In step Sa, the solvent is methanol, deionized water, or ammonia. And / or, in step Sa, the molar ratio of zinc nitrate to 2-methylimidazole is 1:(3.8~4.2). And / or, in step Sa, the aging time is 10 to 24 hours; And / or, in step Sc, the solvent is methanol; And / or, in step Sc, the drying temperature is 60~80℃.

4. The reversible battery as described in claim 1, characterized in that, In step S1, X in ZIF-8-X is the heat treatment temperature of ZIF-8, in degrees Celsius, and 450≤X≤550; And / or, in step S1, the loading of ZIF-8-X on the negative electrode current collector is 1.2~1.8 mg / cm³. 2 ; And / or, in step S1, the heat treatment is performed by heating to the holding temperature at a heating rate of 2~4℃ / min; And / or, in step S1, the heat treatment holding time is 2 to 4 hours; And / or, in step S1, the heat treatment is carried out in an inert atmosphere or in a tube furnace; And / or, in step S1, the negative electrode current collector is nickel foam.

5. The reversible battery as described in claim 1, characterized in that, In step S3, the constant voltage deposition conditions are as follows: the battery assembled in step S2 is charged at a constant voltage of 2.0~2.4V until its capacity reaches 1.8~2.2 mAh / cm³. 2 ; And / or, in step S3, the battery assembled in step S2 is left to stand for 20 to 30 hours before constant pressure deposition.

6. The reversible battery as described in claim 1, characterized in that, The electrolyte comprises: 0.08~0.12M H2SO4, 0.8~1.2M MnSO4, 0.08~0.12M aniline and 0.8~1.2M ZnSO4; the solvent of the electrolyte is deionized water.

7. The reversible battery as described in claim 6, characterized in that, The electrolyte comprises: 0.1M H2SO4, 1M MnSO4, 0.1M aniline and 1M ZnSO4.

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