Metal-doped manganese dioxide aqueous zinc ion battery positive electrode material and preparation method thereof

Abstract

The invention discloses a preparation method of a metal-doped manganese dioxide aqueous zinc ion battery positive electrode material, which comprises the following steps of: preparing a solution from any one of potassium permanganate, potassium manganate, sodium permanganate and sodium manganate, and recording the solution as a solution A; preparing a solution from any one of oxalic acid, citric acid, formic acid, acetic acid, sodium hydrogen sulfite and phosphorous acid, and recording the solution as a solution B; 2-10 ml of the solution B and aluminum salt are weighed and added into the solution A, ultrasonic dispersion is carried out, stirring is carried out for 20-120 min, and a mixed solution is obtained; and transferring the mixed solution into a polytetrafluoroethylene high-pressure reaction kettle, putting the polytetrafluoroethylene high-pressure reaction kettle into a drying oven at 120-180 DEG C, carrying out heating reaction for 10-24 hours, naturally cooling to room temperature, washing the reactant with water and ethanol, centrifuging, and carrying out vacuum drying to obtain the aluminum-doped delta-MnO2 positive electrode material. The positive electrode material is applied to the field of aqueous zinc ion batteries, the specific capacity of the battery positive electrode is extremely high, the battery positive electrode has very excellent cycling stability and high-rate charge-discharge characteristics, and raw materials used for synthesis are non-toxic and low in price.

Description

Technical Field

[0001] The present invention belongs to the technical field of aqueous zinc-ion batteries, and particularly relates to a cathode material for an aqueous zinc-ion battery of metal-doped manganese dioxide and a preparation method thereof. Background Art

[0002] With the increasing demand for electronic products, lithium-ion batteries have occupied most of the commercial rechargeable battery market due to their ultra-high energy density. However, with the increasingly prominent problems such as high packaging cost of lithium-ion batteries, great harm of organic electrolytes, and uneven global lithium resource distribution, the development prospects of lithium-ion batteries have been seriously hindered. Therefore, the demand for developing low-cost and environmentally friendly batteries has become more and more urgent. In recent years, a new type of rechargeable aqueous battery - aqueous zinc-ion battery has received more and more attention due to its low cost, high safety, and high environmental friendliness, and the research on its cathode materials has also become a hot topic.

[0003] In recent years, due to the advantages of low cost, non-toxicity, rich materials, and large theoretical capacity of MnO2, it has become one of the most popular cathode materials in the field of aqueous zinc-ion batteries. MnO2 can be roughly divided into tunnel type, layered type, and spinel type according to the crystal structure. Although tunnel-type MnO2 exhibits excellent Zn 2+ diffusion ability and structural stability, the tunnel structure limits the zinc storage capacity of MnO2 and affects the specific capacity of the material. In addition, the structure of spinel-type MnO2 is closely packed, and Zn 2+ is difficult to embed, resulting in low capacity. In comparison, layered δ-MnO2 has a relatively large interlayer spacing and faster Zn 2+ diffusion ability, which is beneficial to the storage and transportation of Zn 2+ and may be the most ideal MnO2 cathode material. However, during the electrochemical reaction, interlayer phase transformation is likely to occur, resulting in structural collapse and seriously affecting stability. Summary of the Invention

[0004] The purpose of the embodiments of the present invention is to provide a preparation method for a cathode material of an aqueous zinc-ion battery of metal-doped manganese dioxide, which realizes the support for δ-MnO2 through metal doping; improves the specific capacity of the battery cathode, cycle stability, and charge-discharge rate.

[0005] Another object of the present invention is to provide a cathode material for an aqueous zinc-ion battery of metal-doped manganese dioxide.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is a preparation method for a cathode material of an aqueous zinc-ion battery of metal-doped manganese dioxide,

[0007] S1. Prepare a manganese-containing oxidant solution, denoted as solution A;

[0008] S2. Prepare an acidic reducing agent solution, denoted as solution B;

[0009] S3. Measure and add solution B and metal salt to solution A, ultrasonically disperse and stir for a period of time to obtain a mixed solution C;

[0010] S4. Transfer the mixed solution C to a polytetrafluoroethylene high-pressure reactor, place it in an oven for heating reaction, naturally cool to room temperature, wash the reactants with water and ethanol and centrifuge, and dry in vacuum to obtain a metal-doped δ-MnO2 cathode material.

[0011] Further; the manganese oxidant solution is specifically any one of potassium permanganate solution, potassium manganate solution, sodium permanganate solution, and sodium manganate solution.

[0012] Further; in the manganese oxidant solution, the concentration of manganese salt is 0.1 - 0.9 mol / L in molar concentration.

[0013] Further; the acidic reducing agent solution is specifically any one of citric acid solution, formic acid solution, acetic acid solution, oxalic acid solution, sodium bisulfite solution, and phosphorous acid solution.

[0014] Further; in the acidic reducing agent solution, the concentration of the acidic reducing agent is 0.1 - 0.6 mol / L.

[0015] Further; in S3, the volume ratio of solution B to solution A is (4 - 14):(70 - 100).

[0016] Further; the metal salt is an aluminum salt, specifically any one of aluminum nitrate, aluminum sulfate, aluminum carbonate, and aluminum chloride, and the molar volume ratio of the aluminum salt to solution A is (0.005 - 0.09):(70 - 100) mol / ml.

[0017] Further; during the heating process of S4, the oven temperature is 120 - 200 °C, and the heating reaction time is 10 - 24 h.

[0018] A metal-doped manganese dioxide aqueous zinc-ion battery cathode material prepared by the above method.

[0019] Compared with the prior art, the beneficial effects of the present invention are: The present invention prepares an aluminum-doped δ-MnO2 cathode material by a hydrothermal method; the doping of high-charge-density Al 3+ will bring a large amount of crystal water into the interlayer of δ-MnO2. The crystal water in the interlayer has a lubricating effect, which can improve the electrostatic shielding effect and reduce the repulsive force suffered by Zn 2+ when it embeds into the cathode lattice. Coupled with Al 3 +The embedding provides support for the δ-MnO2 layered structure; the combination of crystal water and Al 3+ improves the structural stability of the battery cathode, reduces the conductivity of the electrode, and thus effectively improves the cycle stability and rate performance of the battery; moreover, the main raw materials of this cathode material are non-toxic and low in price, making the prepared cathode material green, safe and low in cost. Brief Description of the Drawings

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0021] Figure 1 is the rate performance diagram of the aluminum-doped δ-MnO2 cathode at different current densities;

[0022] Figure 2 is the cycle performance diagram of the battery with the aluminum-doped δ-MnO2 cathode at a current density of 500 mA / g. Detailed Embodiments

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0024] The present invention provides a preparation method for a cathode material of a metal-doped manganese dioxide aqueous zinc ion battery, and the specific steps are as follows:

[0025] S1. Prepare a manganese-containing oxidant solution and an acidic reducing agent solution;

[0026] S2. Measure a small amount of acidic reducing agent solution and metal salt and add them to the manganese-containing oxidant solution, disperse ultrasonically, and stir for a period of time to obtain a mixed solution;

[0027] S3. Transfer the mixed solution to a polytetrafluoroethylene high-pressure reaction kettle, place it in an oven for heating reaction, naturally cool to room temperature, wash the reactants with water and ethanol and centrifuge, and dry in vacuum to obtain a metal-doped δ-MnO2 cathode material.

[0028] Example 1

[0029] S1. Weigh 0.01 mol of potassium permanganate and add it to 70 ml of distilled water, stir to dissolve to obtain a potassium permanganate solution; weigh 0.01 mol of citric acid and add it to 100 mL of distilled water, dissolve evenly to obtain a citric acid solution;

[0030] S2. Measure 4 ml of the citric acid solution and 0.01 mol of aluminum nitrate and add them to the potassium permanganate solution, disperse ultrasonically, and stir for 20 min to obtain a mixed solution;

[0031] S3. Transfer the mixed solution to a polytetrafluoroethylene high-pressure reaction kettle, place it in an oven and heat it at 160 °C for 12 h, naturally cool to room temperature, wash the reactants with water and ethanol and centrifuge, and dry in vacuum to obtain aluminum-doped δ-MnO2.

[0032] Example 2

[0033] S1. Weigh 0.02 mol of potassium permanganate and add it to 70 ml of distilled water, stir to dissolve to obtain a potassium permanganate solution; weigh 0.02 mol of oxalic acid and add it to 100 mL of distilled water, dissolve evenly to obtain an oxalic acid solution;

[0034] S2. Measure 14 ml of the oxalic acid solution and 0.05 mol of aluminum sulfate and add them to the potassium permanganate solution, disperse ultrasonically, and stir for 30 min to obtain a mixed solution;

[0035] S3. Transfer the mixed solution to a polytetrafluoroethylene high-pressure reaction kettle, place it in an oven and heat it at 120 °C for 24 h, naturally cool to room temperature, wash the reactants with water and ethanol and centrifuge, and dry in vacuum to obtain aluminum-doped δ-MnO2.

[0036] Example 3

[0037] S1. Weigh 0.03 mol of potassium manganate and add it to 70 ml of distilled water, stir to dissolve to obtain a potassium manganate solution; weigh 0.03 mol of formic acid and add it to 100 mL of distilled water, dissolve evenly to obtain a formic acid solution;

[0038] S2. Measure 12 ml of the formic acid solution and 0.02 mol of aluminum carbonate and add them to the potassium manganate solution, disperse ultrasonically, and stir for 40 min to obtain a mixed solution;

[0039] S3. Transfer the mixed solution to a polytetrafluoroethylene high-pressure reaction kettle, place it in an oven and heat it at 200 °C for 10 h, naturally cool to room temperature, wash the reactants with water and ethanol and centrifuge, and dry in vacuum to obtain aluminum-doped δ-MnO2.

[0040] Example 4

[0041] S1. Weigh 0.04 mol of potassium manganate and add it to 70 ml of distilled water, stir to dissolve to obtain a potassium manganate solution; weigh 0.04 mol of acetic acid and add it to 100 mL of distilled water, dissolve evenly to obtain an acetic acid solution;

[0042] S2. Measure 10 ml of acetic acid solution and 0.05 mol of aluminum chloride and add them to the potassium manganate solution, disperse ultrasonically, and stir for 50 min to obtain a mixed solution;

[0043] S3. Transfer the mixed solution to a polytetrafluoroethylene high-pressure reaction kettle, place it in an oven and heat at 140 °C for 18 h, naturally cool to room temperature, wash the reactants with water and ethanol and centrifuge, and dry under vacuum to obtain aluminum-doped δ-MnO2.

[0044] Example 5

[0045] S1. Weigh 0.05 mol of sodium permanganate and add it to 70 ml of distilled water, stir to dissolve to obtain a sodium permanganate solution; weigh 0.05 mol of sodium bisulfite and add it to 100 ml of distilled water, dissolve evenly to obtain a sodium bisulfite solution;

[0046] S2. Measure 6 ml of sodium bisulfite solution and 0.03 mol of aluminum sulfate and add them to the sodium permanganate solution, disperse ultrasonically, and stir for 60 min to obtain a mixed solution;

[0047] S3. Transfer the mixed solution to a 100 ml polytetrafluoroethylene high-pressure reaction kettle, place it in an oven and heat at 180 °C for 14 h, naturally cool to room temperature, wash the reactants with water and ethanol and centrifuge, and dry under vacuum to obtain aluminum-doped δ-MnO2.

[0048] Example 6

[0049] S1. Weigh 0.06 mol of sodium manganate and add it to 70 ml of distilled water, stir to dissolve to obtain a sodium manganate solution; weigh 0.06 mol of phosphorous acid and add it to distilled water, dissolve evenly to obtain a phosphorous acid solution;

[0050] S2. Measure 8 ml of phosphorous acid solution and 0.09 mol of aluminum nitrate and add them to the potassium permanganate solution, disperse ultrasonically, and stir for 60 min to obtain a mixed solution;

[0051] S3. Transfer the mixed solution to a 100 ml polytetrafluoroethylene high-pressure reaction kettle, place it in an oven and heat at 120 °C for 24 h, naturally cool to room temperature, wash the reactants with water and ethanol and centrifuge, and dry under vacuum to obtain aluminum-doped δ-MnO2.

[0052] Example 7

[0053] Weigh 0.01 mol of potassium permanganate in S1 and add it to 100 ml of distilled water; the remaining steps are the same as those in Example 1.

[0054] Example 8

[0055] Weigh 0.09 mol of potassium permanganate in S1 and add it to 100 ml of distilled water; the remaining steps are the same as those in Example 1.

[0056] Example 9

[0057] Measure 4 ml of citric acid solution and 0.005 mol of aluminum nitrate in S2 and add them to the potassium permanganate solution; the remaining steps are the same as those in Example 7.

[0058] Example 10

[0059] Measure 4 ml of citric acid solution and 0.09 mol of aluminum nitrate in S2 and add them to the potassium permanganate solution; the remaining steps are the same as those in Example 7.

[0060] Example 11

[0061] Weigh 0.01 mol of potassium permanganate in S1 and add it to 80 ml of distilled water; the remaining steps are the same as those in Example 1.

[0062] Example 12

[0063] Weigh 0.01 mol of potassium permanganate in S1 and add it to 90 ml of distilled water; the remaining steps are the same as those in Example 1.

[0064] Comparative Example 1

[0065] To compare the effect of aluminum ion doping on the battery performance, the process of S2 is not carried out, and the remaining steps are the same as those in Example 1.

[0066] Comparative Example 2

[0067] To compare the effect of acidic reducing agent and basic reducing agent on the battery performance, change the steps in S1 to weigh 0.06 mol of sodium manganate and add it to 70 ml of distilled water, stir to dissolve to obtain a sodium manganate solution; weigh 0.06 mol of sodium hydroxide (basic reducing agent) and add it to 100 mL of distilled water, dissolve evenly to obtain a sodium hydroxide solution, and the remaining steps are the same as those in Example 1.

[0068] The manganese-containing oxidant of the present invention is the main raw material for synthesizing the composite cathode material of the present invention. The manganese-containing oxidant slowly forms δ-MnO2 under the action of an acidic reducing agent and a hydrothermal reaction; the acidic reducing agent mainly has two functions during the reaction. On the one hand, it adjusts the pH value of the system to make the system acidic, so that Al 3+On the one hand, it can exist stably. On the other hand, the reducing agent provides conditions for the slow formation of δ-MnO2. The δ-MnO2 has an important characteristic, in which part of the Mn 4+ is replaced by Mn 3+ , resulting in a large number of negative charges in the structure of δ-MnO2. The aluminum salt mainly has two functions during the reaction. On the one hand, Al 3+ is embedded in the layered δ-MnO2 to replace Mn 3+ , playing a role in supporting the structure. On the other hand, a large amount of crystal water is brought into the material.

[0069] Using the aluminum-doped δ-MnO2 cathode material prepared in Examples 1-Comparative Example 2 as the active material, polyvinylidene fluoride as the binder, and acetylene black as the conductive agent, and then mixing them evenly and coating them on the stainless steel mesh substrate to prepare the cathode. Then, a CR2020 type stainless steel coin-shaped battery case was selected, with zinc foil as the anode, a 2mol / L zinc sulfate and 0.1mol / L manganese sulfate aqueous solution as the electrolyte, a Waterman glass fiber filter paper as the separator and the prepared cathode to assemble an aqueous zinc ion battery.

[0070] The performance of the obtained battery was tested. The rate performance of the cathode material obtained in Example 1 after being assembled into an aqueous zinc ion battery at different current densities is as Figure 1 shown. The specific capacity of the cathode material is as high as 308.8 mAh / g at a current density of 0.1 A / g, and its specific capacity is still as high as 110.9 mAh / g at a current density of 2 A / g, showing very excellent specific capacity and high-current charge-discharge characteristics.

[0071] The cycling performance at a current density of 500 mA / g is as Figure 2 shown. Its initial discharge specific capacity is as high as 202.8 mAh / g. After 300 cycles, the battery is further activated, and the discharge specific capacity reaches 247.3 mAh / g, and the charge-discharge efficiency reaches almost 100%. This is mainly because the combination of crystal water and Al 3+ improves the structural stability of the battery cathode, reduces the conductivity of the electrode, and thus greatly improves the rate characteristics and cycling stability of the battery.

[0072] Table 1 shows the cycling performance of the aqueous zinc ion batteries assembled with the cathode materials described in Examples 1-Comparative Example 2 at a current density of 500 mA / g.

[0073] Table 1 Cycling performance of aqueous zinc ion batteries in Examples 1 to Comparative Example 2

[0074] Initial cycle (mAh / g) 300 cycles (mAh / g) Example 1 202.8 247.3 Example 2 217.6 255.9 Example 3 221.3 240.6 Example 4 214.8 254.6 Example 5 193.7 237.2 Example 6 210.3 251.3 Comparative Example 1 150.6 60.3 Comparative Example 2 140.1 59.4

[0075] As can be seen from Table 1, taking Comparative Example 1 as a reference, after doping with aluminum ions in Examples 1 to 7 in Table 1, both the initial cycle capacity and the capacity after 300 cycles of the battery increased significantly. It shows that the combination of doping Al 3+ and the incorporated crystal water improves the structural stability of the battery cathode, thus greatly improving the rate performance and cycle stability of the battery;

[0076] As can be seen from Table 1, taking Comparative Example 2 as a reference, after using different acidic reducing agents in Examples 1 to 7 in Table 1, both the initial cycle capacity and the capacity after 300 cycles of the battery increased significantly. On the one hand, it shows that the acidic reducing agent has universality. On the other hand, it shows that the acidic reducing agent provides conditions for the slow formation of δ-MnO2 and adjusts the pH, providing a better environment for the existence of Al 3+ .

[0077] Each embodiment in this specification is described in a related manner. For the same or similar parts among the embodiments, reference can be made to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and for the relevant parts, reference can be made to the partial description of the method embodiment.

[0078] The above are only the preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A preparation method of a metal-doped manganese dioxide aqueous zinc-ion battery cathode material, characterized in that ； S1. Prepare a manganese-containing oxidant solution, denoted as solution A; S2. Prepare an acidic reducing agent solution, denoted as solution B; S3. Measure solution B and a metal salt and add them to solution A, ultrasonically disperse and stir for a period of time to obtain a mixed solution C; S4. Transfer the mixed solution C to a polytetrafluoroethylene high-pressure reactor, place it in an oven for heating reaction, naturally cool to room temperature, wash the reactant with water and ethanol and centrifuge, and dry it under vacuum to obtain a metal-doped δ-MnO2 cathode material for an aqueous zinc-ion battery.

2. The preparation method of a cathode material for an aqueous zinc-ion battery based on metal-doped manganese dioxide according to claim 1, characterized in that; The manganese oxidant solution is specifically any one of potassium permanganate solution, potassium manganate solution, sodium permanganate solution, and sodium manganate solution.

3. The preparation method of a metal-doped manganese dioxide aqueous zinc ion battery cathode material according to claim 2, characterized in that; In the manganese oxidant solution, the concentration of the manganese salt is 0.1 - 0.9 mol / L in molar concentration.

4. The preparation method of a metal-doped manganese dioxide aqueous zinc-ion battery cathode material according to claim 1, characterized in that; The acidic reducing agent solution is specifically any one of citric acid solution, formic acid solution, acetic acid solution, oxalic acid solution, sodium bisulfite solution, and phosphorous acid solution.

5. The preparation method of a metal-doped manganese dioxide aqueous zinc ion battery cathode material according to claim 4, characterized in that; In the acidic reducing agent solution, the concentration of the acidic reducing agent is 0.1 - 0.6 mol / L.

6. The preparation method of a metal-doped manganese dioxide aqueous zinc ion battery cathode material according to claim 1, characterized in that; In S3, the volume ratio of solution B to solution A is (4 - 14):(70 - 100).

7. A method for preparing a positive electrode material for an aqueous zinc ion battery with metal-doped manganese dioxide, characterized in that; The metal salt is an aluminum salt, specifically any one of aluminum nitrate, aluminum sulfate, aluminum carbonate, and aluminum chloride. The molar volume ratio of the aluminum salt to solution A is (0.005 - 0.09):(70 - 100) mol / ml.

8. A method for preparing a positive electrode material for a metal-doped manganese dioxide aqueous zinc ion battery according to claim 1, characterized in that; During the heating process in S4, the oven temperature is 120 - 200 °C, and the heating reaction time is 10 - 24 h.

9. A cathode material for an aqueous zinc-ion battery with metal-doped manganese dioxide prepared by the method according to any one of claims 1 - 8.

Images