A manganese-based metal organic complex material, a preparation method and application thereof

Abstract

The present application relates to a kind of manganese-based metal organic complex material and its preparation method and application.The manganese-based metal organic complex is composed of divalent manganese ion and organic polymer ligand;The organic polymer ligand contains carboxyl functional group, and the molecular weight is 5000~30000000;The molecular formula of the manganese-based metal organic complex material is [Mn x (PAL)2] n ·yH2O, wherein PAL is polyacrylate monomer [CH2CHCOO] ‑ , 0.5 x≤1, n=25~150,000;Preferably, the organic polymer ligand is at least one of the molecular weight 5000~30000000 polyacrylic acid sodium.

Description

Technical Field

[0001] This invention relates to a method for preparing and applying a manganese-based metal-organic complex material, belonging to the field of aqueous battery cathode material preparation technology. Background Technology

[0002] Aqueous zinc-ion batteries, especially aqueous zinc-manganese batteries, have become the most promising large-scale energy storage electrochemical devices in recent years due to their extremely high safety, specific capacity, and abundant resource reserves. The cathode materials for aqueous zinc-manganese batteries are generally various crystalline forms of manganese-based oxides (α-MnO2, β-MnO2, δ-MnO2, etc.). Their reaction mechanism is complex, involving the presence of Zn... 2+ / H + Co-intercalation and deintercalation and MnO2 / Mn 2+ The deposition and dissolution reactions, as well as the various phase transitions that occur during cycling (MnO2→MnOOH→ZnMnO2), contribute to the poor cycling stability of traditional manganese-based oxide materials. Furthermore, traditional manganese-based oxide cathode materials have a lower reaction voltage (1.35V vs. ZnMnO2). 2+ The presence of zinc (Zn) limits its energy density, and achieving a higher output voltage requires connecting more cells in series, which complicates battery assembly. These issues severely limit the application of manganese-based oxides in aqueous zinc-manganese batteries.

[0003] To address the low voltage issue, researchers achieved MnO2 / M ... 2+ The complete dissolution and deposition reaction of (1.20V vs. SHE), and Mn 3+ / Mn 2+ High-voltage redox reaction (1.51V vs. SHE); high-voltage reaction of metallic zinc at 1.5V was achieved by introducing a redox medium under weakly acidic conditions; EDTA-Mn(III) / EDTA-Mn(II) (1.6V vs. Zn) was achieved using the liquid-phase organic ligand EDTA. 2+ / Zn) However, the above scheme has the following drawbacks: (1) The introduction of a strong acid system will cause severe corrosion to metallic zinc, eventually causing the full cell to fail rapidly due to negative electrode corrosion; (2) Bipolar membranes can be used to separate strong acid from zinc negative electrode, but such ion-selective membranes are expensive and have poor lifespan; (3) The introduction of redox media will cause a shuttle effect, which will also cause negative electrode corrosion and battery failure; (4) Liquid phase Mn 3+ / Mn 2+ The reaction exhibits a shuttle effect. Summary of the Invention

[0004] To overcome the shortcomings of current high-voltage zinc-manganese battery technology, the present invention aims to provide a manganese-based complex material, its preparation method, and its application. The manganese-based organometallic complex material increases the reaction voltage, thereby increasing the overall energy density of the battery.

[0005] On one hand, this invention provides a manganese-based organometallic complex material, wherein the manganese-based organometallic complex is composed of divalent manganese ions and an organic polymer ligand. The organic polymer ligand contains a carboxyl functional group and has a molecular weight of 5000–30000000; the molecular formula of the manganese-based organometallic complex material is [Mn x (PAL)2] n ·yH2O, where PAL is the polyacrylate monomer [CH2CHCOO] - 0.5 < x ≤ 1, n = 25 to 150,000; preferably, the organic polymer ligand is at least one of sodium polyacrylate with different molecular weights (5,000 to 30,000,000).

[0006] In this invention, the manganese-based metal-organic complex material differs from traditional manganese-based oxides and can achieve high-voltage reactions in a weakly acidic sulfate system, thereby avoiding the corrosion problem of the zinc anode in a strong acid electrolyte system.

[0007] Preferably, based on 100% of the total mass of the manganese-based organometallic complex material, the manganese element mass fraction is 10%–30%, and the organic polymer ligand mass fraction is 70%–90%. More preferably, based on 100% of the total mass of the manganese-based organometallic complex material, the manganese element mass fraction is 10%–28%, the organic polymer ligand mass fraction is 60%–85%, and the coordinated H₂O mass fraction is 5%–15%.

[0008] Preferably, the manganese-based metal-organic complex material is an amorphous amorphous structure formed by the cross-linking of divalent manganese ions, and there is no problem of poor material stability caused by the destruction of crystal structure.

[0009] In another aspect, the present invention provides a method for preparing a manganese-based metal-organic complex material, comprising: adding an organic polymer ligand to an aqueous solution of a divalent manganese salt, first stirring to obtain a precipitate, and then washing and drying to obtain the manganese-based metal-organic complex material.

[0010] Preferably, the solute in the divalent manganese salt aqueous solution is a divalent manganese salt, preferably at least one selected from manganese sulfate, manganese nitrate, manganese acetate, and manganese chloride. The concentration of the divalent manganese salt in the aqueous solution can be 0.5–2 mol / L.

[0011] Preferably, the molar ratio of divalent manganese ions and functional groups in the organic polymer ligand in the divalent manganese salt aqueous solution can be 1.0 to 3.0.

[0012] In another aspect, the present invention provides an application of a manganese-based metal-organic complex material in an aqueous battery, wherein the cathode material contains a manganese-based metal-organic complex material.

[0013] Preferably, the mass ratio of manganese-based metal-organic complex material, conductive agent and binder in the positive electrode material is (6-8.5):(1-3):(0.5-1).

[0014] Preferably, the preparation method of the positive electrode material is as follows: weighing manganese-based metal organic complex material, conductive agent and binder in a mass ratio of (6-8.5):(1-3):(0.5-1) and mixing them with solvent to form a slurry; then coating the slurry onto the current collector and drying it to obtain the positive electrode material.

[0015] Preferably, the conductive agent is acetylene black, Super P, or carbon nanotubes;

[0016] The adhesive is polyvinylidene fluoride, polytetrafluoroethylene, or styrene-butadiene rubber;

[0017] The solvent is N-methylpyrrolidone or water;

[0018] The current collector is a metal foil.

[0019] The beneficial effects of this invention are:

[0020] (1) This invention provides a manganese-based metal-organic complex in which divalent manganese ions coordinate with carboxyl groups in polymer ligands to form strong coordination bonds. During charge and discharge, the carboxyl-stabilized divalent manganese ions are oxidized to form coordinated trivalent manganese ions, thus preventing the trivalent manganese ions from immediately undergoing disproportionation in near-neutral sulfate electrolytes. The manganese element in the material, in a coordinated state, achieves a high-voltage redox reaction PAL-Mn during charge and discharge. 3+ / PAL-Mn 2+ (1.67V vs. Zn) 2+ / Zn) compared to the traditional zinc / manganese oxide battery potential (1.35V vs. Zn) 2+ / Zn) increased by 24%. The material, in a sulfate electrolyte system at 200 mA g -1 Achieving 450mAh g at a current density -1 Specific capacity. In 1A g -1 At a current density, the specific capacity is 120 mAh g. -1 The cycle should be at least 2000 times.

[0021] (2) This invention provides a manganese-based organometallic complex, wherein the carboxyl functional group in the material can re-coordinate with divalent manganese ions added to the electrolyte to achieve the material's regenerative function, thereby achieving excellent cycle stability of the battery; (3) This invention provides a method for preparing a manganese-based organometallic complex, wherein the method involves adding a polymer carboxyl ligand to a divalent manganese salt aqueous solution under normal temperature and pressure, and forming a stable amorphous manganese-based organometallic complex through the coordination and cross-linking adsorption of carboxyl groups and divalent manganese ions. The coordination process between manganese salt and polymer carboxyl ligand only requires a one-step precipitation reaction, and the reaction temperature is low, the time is short, it is simple and easy to operate, and there is no need for high-temperature calcination;

[0022] (4) This invention provides an application of a manganese-based organometallic complex, wherein the application is as a positive electrode material for zinc-ion batteries; the material, as a positive electrode material for zinc-ion batteries, exhibits extremely high reaction voltage and cycle stability, and the manganese-based organometallic complex has a high reaction voltage and cycle stability at 200 mA g. -1 Achieving 450mAh g at a current density -1 The specific capacity, at 1A g -1 At a current density, the specific capacity is 120 mAh g. -1 The cycle should be at least 2000 times. Attached Figure Description

[0023] Figure 1 The X-ray diffraction pattern of manganese polyacrylate (molecular weight 3,000,000 to 7,000,000) material in Example 1 is shown.

[0024] Figure 2 Example 1: Manganese polyacrylate (molecular weight 3,000,000–7,000,000) material at 0.1 mV s -1 Cyclic voltammetry curves at scan rate;

[0025] Figure 3 For Example 1, manganese polyacrylate (molecular weight 3,000,000–7,000,000) material was used at 0.1 A g. -1 Constant current charge-discharge curves at current density;

[0026] Figure 4 For Example 1, the manganese polyacrylate (molecular weight 3,000,000–7,000,000) material was tested at 1.0 A g. -1 Cyclic stability curves at current densities;

[0027] Figure 5 The X-ray diffraction pattern of manganese polyacrylate (molecular weight 5000) material in Example 2 is shown below.

[0028] Figure 6Example 2: Manganese polyacrylate (molecular weight 5000) material at 0.1 mV s -1 Cyclic voltammetry curves at scan rate;

[0029] Figure 7 Example 2: Manganese polyacrylate (molecular weight 5000) material at 0.1A g -1 Constant current charge-discharge curves at current density;

[0030] Figure 8 Example 2: Manganese polyacrylate (molecular weight 5000) material at 1.0 A g -1 Cyclic stability curves at current densities;

[0031] Figure 9 The X-ray diffraction pattern of manganese polyacrylate (molecular weight 30,000,000) material in Example 3 is shown.

[0032] Figure 10 Example 3: Manganese polyacrylate (molecular weight 30,000,000) material at 0.1 mV s -1 Cyclic voltammetry curves at scan rate;

[0033] Figure 11 Example 3: Manganese polyacrylate (molecular weight 30,000,000) material at 0.1 A g -1 Constant current charge-discharge curves at current density;

[0034] Figure 12 Example 3: Manganese polyacrylate (molecular weight 30,000,000) material at 1.0 A g. -1 Cyclic stability curves at current densities;

[0035] Figure 13 The X-ray diffraction pattern of the manganese monoxide material in Comparative Example 1;

[0036] Figure 14 For Comparative Example 1, manganese monoxide material at 0.1 mV s -1 Cyclic voltammetry curves at scan rate;

[0037] Figure 15 For Comparative Example 1, manganese monoxide material was used at 0.1 A g. -1 Constant current charge-discharge curves at current density;

[0038] Figure 16 For Comparative Example 1, manganese monoxide material was used at 1.0 A g. -1 Cyclic stability curves at current densities; Detailed Implementation

[0039] The present invention will be further illustrated by the following embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the present invention.

[0040] In this disclosure, the manganese-based organometallic complex material (manganese polyacrylate) is synthesized by ion exchange precipitation of divalent manganese ions and organic carboxyl polymer ligands in an aqueous solution. Based on 100% of the total mass of the manganese-based organometallic complex material, the mass fraction of manganese element is 13%–28%, the mass fraction of polymer ligands is 60%–70%, and the mass fraction of coordinated H₂O is 5%–15%. Preferably, the divalent manganese salt is a sulfate, nitrate, or chloride salt. Since the sulfate ion in sulfate has the weakest coordinating ability, it is more conducive to the coordination and cross-linking of divalent manganese ions with carboxyl ligands in solution; therefore, sulfate is preferred.

[0041] Preferably, the organic carboxylate polymer ligand is at least one sodium polyacrylate with a molecular weight of 5,000 to 30,000,000. After testing the manganese content of manganese polyacrylate materials prepared with various carboxyl polymer ligands using inductively coupled plasma (ICP) technology, it was found that the manganese polyacrylate materials prepared with sodium polyacrylate ligands with a molecular weight of 3,000,000 to 7,000,000 had the highest manganese content. If the molecular weight of the polymer ligand is too small, the manganese in the material will dissolve; if the molecular weight is too large, the degree of molecular cross-linking of the polymer will be too high, resulting in a decrease in the coordination ability of manganese ions. Therefore, sodium polyacrylate with a molecular weight of 3,000,000 to 7,000,000 is preferred. All the manganese-based organometallic complexes mentioned herein are amorphous structures.

[0042] The following exemplarily illustrates a method for preparing manganese-based organometallic complexes.

[0043] One or more divalent manganese salts, such as manganese sulfate, manganese nitrate, or manganese chloride, are added to deionized water and stirred until a homogeneous and clear solution A is obtained. The concentration of the divalent manganese salt in the aqueous solution is 0.5–2 mol / L. -1 .

[0044] A certain amount of sodium polyacrylate polymer ligand of a certain molecular weight was added to solution A at a rotation speed of 300-600 r / min. After stirring for 0.5 h to 2 h, a powdery white precipitate was obtained.

[0045] In an optional embodiment, the ratio of the molar amount of manganese in solution A to the molar amount of carboxyl groups in the added polymer ligand can be 1.0 to 3.0.

[0046] After filtration, the product is washed with deionized water and anhydrous ethanol and then dried at a temperature of 60℃ to 80℃.

[0047] An application of the manganese-based metal-organic complex described in this invention, wherein the application is as a positive electrode material for zinc-ion batteries.

[0048] Specific applications:

[0049] The manganese-based metal-organic complex material, conductive agent, and binder are mixed and ground in a mass ratio of (6-7):(2-3):(0.5-1), and an organic solvent is added to form a slurry. The slurry is then coated onto a current collector and dried in an oven at 80°C to obtain the positive electrode of the battery. The binder is polyvinylidene fluoride or polytetrafluoroethylene. The conductive agent is acetylene black, Super P, or carbon nanotubes. The solvent is N-methylpyrrolidone. The current collector is stainless steel foil.

[0050] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the appropriate range based on the description herein, and are not intended to be limited to the specific values ​​in the examples below.

[0051] Example 1:

[0052] (1) Dissolve 6.76 g of manganese sulfate monohydrate (0.04 mol) in 40 mL of deionized water and stir until the manganese sulfate is completely dissolved to obtain a concentration of 1 mol L. -1 Aqueous solution of manganese sulfate;

[0053] (2) Add 2g of sodium polyacrylate powder with a molecular weight of 3,000,000 to 7,000,000 (functional group is carboxyl group, and the molar content of functional group is 0.02mol) to the above manganese sulfate aqueous solution (40mL), and obtain a powdery white precipitate after stirring for 30min.

[0054] (3) After washing the precipitate with deionized water and anhydrous ethanol, it was dried in an oven at 60°C to obtain a powdery white material. Based on a total mass of 100% for the manganese-based organometallic complex material, the manganese element mass fraction was 23%, the organic polymer ligand mass fraction was 66%, and the coordinated H₂O mass fraction was 11%.

[0055] Example 2:

[0056] (1) Dissolve 6.76 g of manganese sulfate monohydrate (0.04 mol) in 40 mL of deionized water and stir until the manganese sulfate is completely dissolved to obtain a concentration of 1 mol L. -1 Aqueous solution of manganese sulfate;

[0057] (2) Add 2g of sodium polyacrylate powder with a molecular weight of 5000 (functional group is carboxyl group, and the molar content of functional group is 0.02mol) to the above manganese sulfate aqueous solution (40mL), and obtain a powdery white precipitate after stirring for 30min.

[0058] (3) After washing the precipitate with deionized water and anhydrous ethanol, it was dried in an oven at 60°C to obtain a powdery white material. Based on the total mass of the manganese-based metal-organic complex material as 100%, the mass fraction of manganese element was 13%, the mass fraction of organic polymer ligands was 75%, and the mass fraction of coordinated H2O was 12%.

[0059] Example 3:

[0060] (1) Dissolve 6.76 g of manganese sulfate monohydrate (0.04 mol) in 40 mL of deionized water and stir until the manganese sulfate is completely dissolved to obtain a concentration of 1 mol L. -1 Aqueous solution of manganese sulfate;

[0061] (2) Add 2g of sodium polyacrylate powder with a molecular weight of 30,000,000 (functional group is carboxyl group, and the molar content of functional group is 0.02mol) to the above manganese sulfate aqueous solution (40mL), and obtain a powdery white precipitate after stirring for 30min.

[0062] (3) After washing the precipitate with deionized water and anhydrous ethanol, it was dried in an oven at 60°C to obtain a powdery white material. Based on the total mass of the manganese-based metal-organic complex material as 100%, the mass fraction of manganese element was 16%, the mass fraction of organic polymer ligands was 72%, and the mass fraction of coordinated H2O was 12%.

[0063] Comparative Example 1: Comparative Example 1 is a commercially available manganese monoxide material, wherein the manganese element has the same valence state as the manganese polyacrylate prepared in Examples 1, 2 and 3, which is divalent manganese.

[0064] The testing methods for electrochemical performance are as follows:

[0065] (1) The manganese monoxide material of Comparative Example 1 and the polyacrylic acid manganese complex material of Examples 1, 2 and 3, 350 mg, acetylene black 100 mg and polyvinylidene fluoride 50 mg were mixed and ground in a mass ratio of 7:2:1. Polyvinylidene fluoride was added in the form of a solution, the solvent was N-methylpyrrolidone and the solute was polyvinylidene fluoride. The mass fraction of polyvinylidene fluoride in the solution was 2.5% and the amount added was 2 g. Then 1.5 g of N-methylpyrrolidone was added and stirred and ground in a ball mill at a speed of 350 r / min for 3 hours to form a slurry. The slurry was then coated on a stainless steel foil and dried in an oven at 80°C to obtain the electrode sheet of the zinc ion battery positive electrode.

[0066] (2) The zinc-ion battery positive electrode obtained in step (1) is cut into circular electrode sheets with a diameter of 14 mm using a cutting machine, and then matched with zinc foil with a thickness of 100 μm to assemble a full cell. The electrolyte solutes are ZnSO4 and MnSO4, and the solvent is deionized water. The concentrations of ZnSO4 and MnSO4 are 1 mol / L. -1 and 0.5 mol L -1 Electrochemical testing is performed after battery assembly.

[0067] (3) Electrochemical testing conditions:

[0068] Cyclic voltammetry was performed at 0.1 mV s. -1 The scanning speed is maintained at a certain level.

[0069] The charge-discharge test was a constant current charge-discharge test, at 0.1A g. -1 The process is carried out at a current density;

[0070] Cyclic performance testing was performed using a constant current charge-discharge test at 1.0 Ag. -1 The experiment was conducted at a current density of [specific value].

[0071] X-ray diffraction tests were performed on the manganese polyacrylate complexes of different molecular weights prepared in Examples 1, 2, and 3, and on the manganese monoxide material of Comparative Example 1. The results correspond to... Figure 1 , Figure 5 , Figure 9 and Figure 13 As shown, the manganese polyacrylate complexes synthesized in Examples 1, 2, and 3, with molecular weights of 3,000,000–7,000,000, 5,000, and 30,000,000 respectively, exhibit no sharp diffraction peaks in their X-ray spectra, indicating that they are amorphous materials without a crystalline structure. This suggests that the complexes formed after the coordination adsorption of divalent manganese ions are amorphous materials. Comparative Example 1 matches the standard PDF card for manganese monoxide. The manganese valence state of the manganese monoxide material in Comparative Example 1 is divalent in both the manganese monoxide material and the manganese polyacrylate complexes synthesized in Examples 1, 2, and 3. The difference is that Comparative Example 1 is an oxide, while Examples 1, 2, and 3 are carboxyl complexes. In Examples 1, 2 and 3, the manganese element is in a carboxyl coordination state. The difference is that the molecular weight of the carboxyl ligand is different. The molecular weight of the carboxyl ligand in Example 1 is 3,000,000 to 7,000,000, the molecular weight of the carboxyl ligand in Example 2 is 5,000, and the molecular weight of the carboxyl ligand in Example 3 is 30,000,000.

[0072] Electrochemical tests were performed on the manganese polyacrylate complex with a molecular weight of 3,000,000 prepared in Example 1. The electrochemical tests were conducted at 0.1 mV s-1. -1Cyclic voltammetry curves at scan rate are as follows: Figure 2 As shown. In Example 1, the manganese polyacrylate complex with a molecular weight of 3,000,000 exhibits a pair of high-pressure redox peaks at 1.83V / 1.67V, corresponding to PAL-Mn in the carboxyl coordination state. 3+ / PAL-Mn 2+ Redox reactions were observed. Simultaneously, reduction peaks of manganese oxide in a zinc sulfate-containing electrolyte environment were still present at 1.2V and 1.35V, indicating that the MnSO4 in the electrolyte still underwent a MnO2 / Mn redox reaction. 2+ The presence of this reaction provides higher capacity for Zn / / PAL-Mn batteries. Figure 3 The manganese polyacrylate complex with a molecular weight of 3,000,000 prepared in Example 1 was subjected to a reaction at 0.1 Ag. -1 Charge-discharge curves at current density. They exhibit three voltage plateau regions, with the high-voltage region around 1.7V corresponding to PAL-Mn in the carboxyl coordination state. 3+ / PAL-Mn 2+ The redox reaction, with two low-pressure plateau regions corresponding to the MnO2 / Mn reactions involving MnSO4 in the electrolyte. 2+ The reaction resulted in a specific capacity of 360 mAh g. -1 . Figure 4 0.1 A g of the manganese polyacrylate complex with a molecular weight of 3,000,000 prepared in Example 1. -1 After activation with a small current for 10 cycles, at 1.0 A g -1 Cyclic stability test curves at current density. In Example 1, the specific capacity of the manganese polyacrylate complex increased from 226.4 mAh g⁻¹ in the first 400 cycles. -1 Decreased to 128.8 mAhg -1 After that, due to MnO2 / Mn 2+ Reaction with Mn 3+ / Mn 2+ Both reactions reached a steady state, and the specific capacity remained at 120 mAh g⁻¹ for the subsequent 1600 cycles. -1 The capacity retention rate reached 93.2%.

[0073] Electrochemical tests were performed on the manganese polyacrylate complex with a molecular weight of 5000 prepared in Example 2. The electrochemical tests were conducted at 0.1 mV / s. -1 Cyclic voltammetry curves at scan rate are as follows: Figure 6 As shown. In Example 2, the manganese polyacrylate complex with a molecular weight of 5000 exhibits a pair of high-voltage redox peaks at 1.86V / 1.62V, corresponding to PAL-Mn in the carboxyl coordination state. 3+ / PAL-Mn 2+Redox reactions were observed. Simultaneously, redox peaks of manganese oxides in a zinc sulfate-containing electrolyte environment were still present at 1.6V / 1.35V, indicating that the MnSO4 in the electrolyte still underwent MnO2 / Mn redox reactions. 2+ The presence of this reaction provides higher capacity for Zn / / PAL-Mn batteries. Figure 7 The manganese polyacrylate complex with a molecular weight of 5000 prepared in Example 2 was subjected to a reaction at 0.1 Ag. -1 Charge-discharge curves at current density. They exhibit three voltage plateau regions, with the high-voltage region around 1.7V corresponding to PAL-Mn in the carboxyl coordination state. 3+ / PAL-Mn 2+ Redox reactions, the region below 1.4V corresponds to the MnO2 / Mn reaction involving MnSO4 in the electrolyte. 2+ The reaction, due to the much lower content of coordinated manganese in Example 2 compared to Example 1, resulted in a specific capacity of only 80 mAh g. -1 . Figure 8 0.1A g of the manganese polyacrylate complex with a molecular weight of 5000 prepared in Example 2. -1 After activation with a small current for 10 cycles, at 1.0 A g -1 Cyclic stability test curves at current density. In Example 2, the specific capacity of the manganese polyacrylate complex increased from 252.2 mAh g⁻¹ in the first 120 cycles. -1 Reduced to 64mAh g -1 The capacity retention rate was 25.4%, which is because the polyacrylic acid polymer ligand with a molecular weight of only 5000 is soluble in water, causing the material to dissolve and thus leading to a decline in battery cycle performance.

[0074] Electrochemical tests were performed on the manganese polyacrylate complex with a molecular weight of 30,000,000 prepared in Example 3. The electrochemical tests were conducted at 0.1 mV s-1. -1 Cyclic voltammetry curves at scan rate are as follows: Figure 10 As shown. In Example 3, the manganese polyacrylate complex with a molecular weight of 30,000,000 exhibits a pair of high-pressure redox peaks at 1.88V / 1.66V, corresponding to PAL-Mn in the carboxyl coordination state. 3 + / PAL-Mn 2+ Redox reactions were observed. Simultaneously, redox peaks of manganese oxides in a zinc sulfate-containing electrolyte environment were still present at 1.6V / 1.35V, indicating that the MnSO4 in the electrolyte still underwent MnO2 / Mn redox reactions. 2+ The presence of this reaction provides higher capacity for Zn / / PAL-Mn batteries. Figure 11 The manganese polyacrylate complex with a molecular weight of 30,000,000 prepared in Example 3 was used at 0.1 A g.-1 Charge-discharge curves at current density. They exhibit three voltage plateau regions, with the high-voltage region around 1.7V corresponding to PAL-Mn in the carboxyl coordination state. 3+ / PAL-Mn 2+ Redox reactions, the region below 1.4V corresponds to the MnO2 / Mn reaction involving MnSO4 in the electrolyte. 2+ The reaction has a specific capacity of 100 mAh g. -1 . Figure 13 0.1 Ag of the manganese polyacrylate complex with a molecular weight of 30,000,000 prepared in Example 3. -1 After activation with a small current for 10 cycles, at 1.0 A g -1 Cyclic stability test curves at current density. In Example 3, the specific capacity of the manganese polyacrylate complex increased from 147 mAh g⁻¹ in the first 500 cycles. -1 Reduced to 48mAh g -1 The capacity retention rate was 32.6%, which is because the polyacrylic acid polymer ligand with a molecular weight of 30,000,000 has poor conductivity, resulting in a low specific capacity at higher currents.

[0075] Electrochemical tests were performed on the manganese monoxide material in Comparative Example 1. The electrochemical tests were conducted at 0.1 mV s⁻¹. -1 Cyclic voltammetry curves at scan rate are as follows: Figure 14 As shown. In Comparative Example 1, the manganese monoxide material exhibits two pairs of conventional manganese oxide redox peaks at 1.60V / 1.33V and 1.55V / 1.20V, corresponding to the MnO2 / Mn ratio in the zinc sulfate electrolyte system. 2+ The reaction did not show a high-voltage reduction peak above 1.6V, unlike Examples 1, 2 and 3. Figure 15 For the manganese monoxide material in Comparative Example 1, at 0.1 Ag -1 Charge-discharge curves at current density. The voltage plateau region is only below 1.4V, corresponding to the MnO2 / Mn electrolyte with MnSO4 participation. 2+ The reaction has a specific capacity of 220 mAh g. -1 . Figure 16 For the manganese monoxide material in Comparative Example 1 at 0.1A g -1 After activation with a small current for 10 cycles, at 1.0 A g -1 Cyclic stability test curves at current density. The specific capacity of the manganese monoxide material in Comparative Example 1 increased from 160.8 mAh g⁻¹. -1 Decayed to 71.2 mAh g -1 The capacity retention rate was 44.2%, which is similar to that of traditional Zn / / MnO2 batteries. The capacity decay was caused by the formation of irreversible, low-activity spinel-structured zinc manganate by divalent manganese ions in the electrolyte.

[0076] Examples 1, 2, and 3 all exhibited high-voltage redox potentials above 1.6V. This indicates that the coordination ability of the carboxyl ligand stabilized Mn in a weakly acidic sulfate electrolyte. 3+ , making Mn 3+ / Mn 2+ The redox reaction is achieved in a weakly acidic system. Furthermore, because the carboxyl polymer ligand is poorly soluble in water, the complexed manganese ions are all in a solid phase, eliminating the shuttle effect caused by liquid-phase ligands. Preferably, compared to ligands with other molecular weights, carboxyl polymer ligands with molecular weights of 3,000,000 to 7,000,000 possess the highest coordination ability for divalent manganese ions and excellent stability. The polyacrylate manganese metal organometallic complex material prepared using carboxyl polymer ligands with molecular weights of 3,000,000 to 7,000,000 in Example 1 exhibits the highest cycle stability, the highest stable specific capacity, and the highest discharge voltage, thus possessing the optimal energy density.

Claims

1. A positive electrode material for an aqueous battery, characterized in that, The positive electrode material of the aqueous battery contains a manganese-based organometallic complex material. The manganese-based organometallic complex is an aqueous complex of manganese polyacrylate, which is composed of complexed divalent manganese ions and sodium polyacrylate ligands with carboxyl groups. The complexed divalent manganese ions are all in a solid phase. The molecular weight of the sodium polyacrylate is 5,000 to 30,000,000; Based on the total mass of the manganese-based organometallic complex material as 100%, the mass fraction of manganese element is 10% to 30%, the mass fraction of sodium polyacrylate ligand with carboxyl groups is 60% to 85%, and the mass fraction of coordinated H2O is 5% to 15%.

2. The positive electrode material of the aqueous battery according to claim 1, characterized in that, The manganese-based metal-organic complex material has an amorphous, non-crystalline structure formed by the cross-linking of manganese ions.

3. The positive electrode material of the aqueous battery according to claim 1, characterized in that, The preparation method of the manganese-based metal-organic complex includes: adding sodium polyacrylate ligands with carboxyl groups to a divalent manganese salt aqueous solution, first stirring to obtain a precipitate, and then washing and drying to obtain the manganese-based metal-organic complex material.

4. The positive electrode material of the aqueous battery according to claim 3, characterized in that, The solute in the divalent manganese salt aqueous solution is a divalent manganese salt, selected from at least one of manganese sulfate, manganese nitrate, manganese acetate, and manganese chloride; the concentration of the divalent manganese salt in the divalent manganese salt aqueous solution is 0.5–2 mol / L.

5. The positive electrode material of the aqueous battery according to claim 3 or 4, characterized in that, The molar ratio of divalent manganese ions and functional groups in sodium polyacrylate ligands with carboxyl groups in the divalent manganese salt aqueous solution is 1.0 to 3.

0.

6. The positive electrode material of the aqueous battery according to any one of claims 1-4, characterized in that, The mass ratio of manganese-based metal organic complex material, conductive agent and binder in the positive electrode material is (6-8.5):(1-3):(0.5-1).

7. The positive electrode material of the aqueous battery according to claim 6, characterized in that, The method for preparing the positive electrode material is as follows: weigh manganese-based metal organic complex material, conductive agent and binder in a mass ratio of (6-8.5):(1-3):(0.5-1) and mix them with solvent to form a slurry; then coat the slurry onto the current collector and dry it to obtain the positive electrode material.

8. The positive electrode material of the aqueous battery according to claim 7, characterized in that, The conductive agent is acetylene black, Super P, or carbon nanotubes. The adhesive is polyvinylidene fluoride, polytetrafluoroethylene, or styrene-butadiene rubber; The solvent is N-methylpyrrolidone or water; The current collector is a metal foil.

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