Zinc metal battery with multifunctional protective layer and preparation method of negative electrode of zinc metal battery

Abstract

The invention relates to the technical field of metal batteries, in particular to a zinc metal battery with a multifunctional protective layer and a preparation method of a negative electrode of the zinc metal battery, firstly, natural diatomite is subjected to high-temperature calcination, and the calcined diatomite is subjected to soaking treatment with an alkali solution and then subjected to secondary calcination. Then adding an N-methyl-pyrrolidone (NMP) solution, and fully stirring with polyvinylidene fluoride (PVDF), so as to obtain a mixture slurry; and finally, coating the slurry on a zinc foil through a tape casting method, and drying to obtain the zinc metal battery negative electrode. According to the zinc metal battery negative electrode disclosed by the invention, zinc ions are uniformly deposited due to a porous structure and a selective ion channel of the protective layer, and more importantly, the diatomite generates a protonation effect in a weakly acidic electrolyte environment, so that the microenvironment around the zinc negative electrode is regulated and controlled; generation of dendritic crystals and generation of side reactions are further reduced, and the cycle life of the battery is prolonged; and the preparation process is simple, low in cost and suitable for large-scale production.

Description

Technical Field

[0001] The present invention relates to the technical field of metal batteries, and in particular to a zinc metal battery with a multifunctional protective layer and a method for preparing a negative electrode thereof. Background Art

[0002] During the charge and discharge process of zinc metal batteries, zinc dendrite growth, zinc metal corrosion and hydrogen evolution are prone to occur on the surface of the negative zinc metal, which can lead to battery short circuit, battery expansion failure, poor reversibility and low cycle life.

[0003] In view of the above problems, constructing an artificial zinc negative electrode protective layer is considered to be the most direct, simplest and most practical method. Among various protective layer materials, inorganic natural mineral material protective layers have attracted widespread attention because of their abundant reserves, low cost and environmental friendliness. For example, Kang et al. coated porous nano-CaCO3 on the surface of the zinc negative electrode, utilized the porous characteristics of the coating layer, guided the deposition of zinc ions in the electrochemical reaction, and thus reduced the formation of dendrites. At the same time, due to the isolation effect of the CaCO3 layer, the contact between zinc and the electrolyte is reduced, thereby reducing the corrosion of zinc metal and the hydrogen evolution reaction, thereby improving the performance of the battery. Similarly, predecessors also used natural inorganic mineral materials such as kaolin and montmorillonite as protective layers for zinc negative electrode protection.

[0004] However, the existing inorganic natural mineral material protective layer is only physically regulated by the material's own structure, which may lose stability during the battery cycle, resulting in a weakened protective effect. Or because the preparation process is often complicated and costly, it limits its promotion in practical applications. Summary of the invention

[0005] The purpose of the present invention is to provide a zinc metal battery with a multifunctional protective layer and a method for preparing a negative electrode thereof, aiming to design a zinc metal battery with a multifunctional protective layer that can inhibit dendrite growth through its own structure and achieve corrosion resistance by inhibiting internal side reactions of the battery by adjusting the interface environment.

[0006] To achieve the above object, the present invention provides a zinc metal battery with a multifunctional protective layer and a method for preparing a negative electrode thereof, comprising the following steps:

[0007] Step 1: calcining diatomite at high temperature, soaking the calcined diatomite in an alkaline solution, and then calcining the pretreated diatomite at high temperature for a second time;

[0008] Step 2: adding the treated diatomaceous earth into the N-methyl-pyrrolidone solution and fully stirring with the polyvinylidene fluoride to obtain a mixture slurry;

[0009] Step 3: coating the mixture slurry onto a zinc foil by a tape casting method and drying the mixture to obtain a negative electrode of a zinc metal battery.

[0010] Optionally, the alkaline solution is one or more of sodium hydroxide, potassium hydroxide and ammonia water, and the concentration is 1 mol / L-5 mol / L.

[0011] Optionally, the high temperature calcination in step 1 is carried out at a temperature of 350-550° C. for 1-3 hours; and the immersion in the alkaline solution is carried out at a temperature of 50-85° C. for 2-8 hours.

[0012] Optionally, in step 2, the mass ratio of the alkaline solution, the N-methyl-pyrrolidone, the polyvinylidene fluoride and the diatomaceous earth is 20-25 g: 4-5 g: 0.06-0.2 g: 0.6-2 g.

[0013] Optionally, in step 2, the stirring rate is 800 r / min and the time is 6-8 h.

[0014] Optionally, the execution process of step 3 is specifically to apply the mixed slurry to a single side of the zinc foil by a casting method, let it stand naturally for 1 hour, build a skeleton of the protective layer on the zinc foil, put the zinc foil coated with the protective layer into an oven, and dry it at 60°C for 8 hours to obtain the zinc metal battery negative electrode.

[0015] The present invention also proposes a zinc metal battery with a multifunctional protective layer, wherein the negative electrode is prepared using the method for preparing a zinc metal battery negative electrode with a multifunctional protective layer, and also includes a positive electrode, wherein the positive electrode material includes at least one of a manganese-based material, a vanadium-based material, a sulfide, a selenide, and a Prussian blue analogue.

[0016] The present invention provides a zinc metal battery with a multifunctional protective layer and a method for preparing the negative electrode thereof, wherein diatomaceous earth is subjected to high temperature calcination, then soaked in an alkaline solution, and then subjected to secondary high temperature calcination to obtain treated diatomaceous earth, which is then added to an N-methyl-pyrrolidone solution and fully stirred with polyvinylidene fluoride to obtain a mixture slurry, and the slurry is coated on a zinc foil by a casting method and dried at a constant temperature to obtain a zinc metal battery negative electrode. The zinc metal battery negative electrode can guide the zinc ion deposition process due to the porous structure and selective ion channels of the protective layer, thereby achieving uniform zinc ion deposition and avoiding dendrites, and the artificial protective layer isolates the zinc metal negative electrode from direct contact with the electrolyte, thereby inhibiting the corrosion of the zinc negative electrode and the generation of hydrogen evolution. More importantly, diatomaceous earth has a large number of Si-OH bonds, which will undergo a protonation effect in the electrolyte to produce a large amount of Si-OH2 +, so that the protective layer has a strong positive charge and changes the anode interface environment, which causes a large number of anions in the electrolyte to be fixed in the outer layer, which also promotes the desolvation process and further reduces side reactions. The multifunctional artificial protective layer is also rich in Si-O bonds and -OH bonds, which can form hydrogen bonds with water molecules in the electrolyte, thereby inhibiting the activity of water, reducing side reactions and corrosion, and accelerating the Zn 2+ Therefore, the electrochemical performance of the battery can be further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a schematic flow chart of the steps of a zinc metal battery with a multifunctional protective layer and a method for preparing a negative electrode thereof according to the present invention.

[0019] Figure 2 It is a schematic diagram comparing the deposition of zinc ions on the negative electrode of a zinc metal battery with bare zinc and a zinc metal battery with a multifunctional protective layer in a specific embodiment of the present invention.

[0020] Figure 3 It is a SEM image of the zinc metal battery negative electrode with a multifunctional protective layer and the bare zinc surface in a specific embodiment of the present invention.

[0021] Figure 4 is a SEM image of a cross section of a negative electrode of a zinc metal battery having a multifunctional protective layer in a specific embodiment of the present invention.

[0022] Figure 5 The specific embodiment of the present invention is 8mA cm -2 , 1mAh cm -2 Symmetrical battery long-term cycle test diagram under current density.

[0023] Figure 6 This is a full-battery charge-discharge cycle test diagram of a zinc metal battery negative electrode assembly with a multifunctional protective layer according to a specific embodiment of the present invention. DETAILED DESCRIPTION

[0024] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0025] See also Figure 1 The present invention provides a zinc metal battery with a multifunctional protective layer and a method for preparing a negative electrode thereof, comprising the following steps:

[0026] S1: calcining diatomite at high temperature, soaking the calcined diatomite in an alkaline solution, and then calcining the pretreated diatomite at high temperature for a second time;

[0027] S2: adding the treated diatomaceous earth to the N-methyl-pyrrolidone solution and fully stirring with the polyvinylidene fluoride to obtain a mixture slurry;

[0028] S3: coating the mixture slurry onto a zinc foil by a casting method and drying the mixture to obtain a negative electrode for a zinc metal battery.

[0029] Specifically, in step S1, the alkaline solution is sodium hydroxide, potassium hydroxide, ammonia water, etc., with a concentration of 1mol / L-5mol / L. High-temperature calcination requires calcination at 350-550°C in a muffle furnace for 1-3h; the alkaline solution pretreatment requires heating at 50-85°C for 2-8h to create a large amount of (Si-OH), and then secondary high-temperature calcination requires calcination at 250-350°C in a muffle furnace for 1-3h.

[0030] In step S2, the stirring rate is 800 r / min, and the time is 6-8 hours. The mass ratio of the alkaline solution, the N-methyl-pyrrolidone, the polyvinylidene fluoride and the diatomaceous earth is 20-25 g: 4-5 g: 0.06-0.2 g: 0.6-2 g.

[0031] In step 3, the mixture slurry is coated on one side of the zinc foil by a casting method and allowed to stand naturally for 1 hour. After constructing a skeleton of the protective layer on the zinc foil, the zinc foil coated with the protective layer is placed in an oven and dried at 60°C for 8 hours to obtain a zinc metal battery negative electrode.

[0032] The negative electrode of the zinc metal battery has a uniform selective ion channel, and the thickness of the protective layer is controllable, about 55μm to 65μm. The negative electrode of the zinc metal battery is rich in various groups, such as the zinc-philic group Si-OH bond and Si-O bond.

[0033] The present invention also proposes a zinc metal battery with a multifunctional protective layer, wherein the negative electrode is prepared using the method for preparing a zinc metal battery negative electrode with a multifunctional protective layer, and also includes a positive electrode, wherein the positive electrode material includes at least one of a manganese-based material, a vanadium-based material, a sulfide, a selenide, and a Prussian blue analogue.

[0034] See also Figures 2 to 6 The following is a further description of the method for preparing the zinc metal battery negative electrode with a multifunctional protective layer in combination with specific examples:

[0035] In contrast, Figure 2 (a) is a schematic diagram of uneven deposition of bare zinc. Figure 2 (b) is a schematic diagram of uniform deposition of the negative electrode of a zinc metal battery with a multifunctional protective layer according to the present invention.

[0036] Example 1

[0037] The following steps are involved:

[0038] (1) 0.2 g of diatomaceous earth was calcined at 350° C. for 2 h, and then added to 25 mL of 1 mol / L sodium hydroxide solution and soaked at 50° C. for 6 h. The soaked diatomaceous earth was calcined again at 250° C. for 1 h to obtain the treated diatomaceous earth.

[0039] (2) The treated diatomaceous earth described in (1) was added to 4.6 g of N-methyl-pyrrolidone solution and stirred at 800 r / min for 6 h to obtain a uniform and stable diatomaceous earth precursor solution.

[0040] (3) The diatomite precursor solution described in (2) is applied to the cut zinc foil by a casting method, and the solution is allowed to stand naturally for 1 hour until a uniform film is formed on the zinc metal surface. The zinc foil coated on one side is placed in an oven and dried at 60° C. for 6 hours to obtain a negative electrode sheet coated with a diatomite artificial protective layer. The scanning electron microscope image of the diatomite protective layer and the zinc metal surface is shown in FIG. Figure 3 ((a) SEM image of the negative electrode of a zinc metal battery with a multifunctional protective layer, (b) SEM image of the bare zinc surface). The thickness of the protective layer is about 58 μm, and the SEM image of its cross section is shown in Figure 4 , zinc ion migration number T(Zn 2+ ) is 0.6.

[0041] (4) After drying, the zinc metal anode coated with a diatomaceous earth protective layer was assembled into a symmetrical battery at 8 mA cm -2 , 1mAhcm -2 The lifespan can reach 2400h at the current density. Figure 5 The negative electrode sheet coated with diatomite artificial protective layer and the positive electrode material Na2V6O 16 ·1.5H2O(NVO), assembled into zinc metal battery in 2M ZnSO4 electrolyte, and charged and discharged at 1A / g current density. After 800 cycles, the capacity retention rate was 90%. The results are shown in Figure 6 .

[0042] Example 2

[0043] The following steps are involved:

[0044] (1) 0.2 g of diatomaceous earth was calcined at 400°C for 2 h, and then added to 25 mL of 1.5 mol / L sodium hydroxide solution and soaked at 80°C for 8 h. The soaked diatomaceous earth was calcined again at 280°C for 1 h to obtain the treated diatomaceous earth.

[0045] (2) The treated diatomaceous earth described in (1) was added to 4.2 g of N-methyl-pyrrolidone solution and stirred at 800 r / min for 7 h to obtain a uniform and stable diatomaceous earth precursor solution.

[0046] (3) The diatomite precursor solution described in (2) is applied to the cut zinc foil by a casting method, and allowed to stand naturally for 1 hour until a uniform film is formed on the zinc metal surface. The zinc foil coated on one side is placed in an oven and dried at 60° C. for 6 hours to obtain a negative electrode sheet coated with a diatomite artificial protective layer. The protective layer thickness is about 68 μm, and the zinc ion migration number T (Zn 2+ ) is 0.51.

[0047] (4) After drying, the zinc metal anode coated with a diatomaceous earth protective layer was assembled into a symmetrical battery at 6 mA cm -2 , 1mAhcm -2 The negative electrode sheet coated with a diatomaceous earth artificial protective layer and the positive electrode material MnO2 are assembled into a zinc metal battery in a 2MZnSO4 electrolyte with a lifespan of up to 1400h under a current density of 2A / g. The charge and discharge test is carried out under a current density of 2A / g, and the capacity retention rate is 88% after 2000 cycles.

[0048] Example 3

[0049] The following steps are involved:

[0050] (1) 0.2 g of diatomaceous earth was calcined at 450°C for 2 h, and then added to 25 mL of 2 mol / L potassium hydroxide solution and soaked at 80°C for 6 h. The soaked diatomaceous earth was calcined again at 300°C for 1 h to obtain the treated diatomaceous earth.

[0051] (2) The treated diatomaceous earth described in (1) was added to 4 g of N-methyl-pyrrolidone solution and stirred at 800 r / min for 8 h to obtain a uniform and stable diatomaceous earth precursor solution.

[0052] (3) The diatomite precursor solution described in (2) was applied to the cut zinc foil by a casting method, and the solution was allowed to stand naturally for 1 hour until a uniform film was formed on the surface of the zinc metal. The zinc foil coated on one side was placed in an oven and dried at 60° C. for 6 hours to obtain a negative electrode sheet coated with a diatomite artificial protective layer. The protective layer thickness was about 62.8 μm, and the zinc ion migration number T (Zn 2+ ) is 0.558.

[0053] (4) After drying, the zinc metal anode coated with a diatomaceous earth protective layer was assembled into a symmetrical battery and then charged at 10 mA cm -2 , 1mAh cm -2 The lifespan can reach 1200h under the current density. The negative electrode sheet coated with diatomite artificial protective layer and the positive electrode material V2O5 were assembled into a zinc metal battery in 2M ZnSO4 electrolyte. The charge and discharge test was carried out under the condition of 1A / g current density. After 1000 cycles, the capacity retention rate was 61%.

[0054] Example 4

[0055] The following steps are involved:

[0056] (1) 0.2 g of diatomaceous earth was calcined at 500° C. for 2 h, and then added to 25 mL of 2 mol / L sodium hydroxide solution and soaked at 80° C. for 6 h. The soaked diatomaceous earth was calcined again at 300° C. for 1 h to obtain treated diatomaceous earth.

[0057] (2) The treated diatomaceous earth described in (1) was added to 4.5 g of N-methyl-pyrrolidone solution and stirred at 800 r / min for 6 h to obtain a uniform and stable diatomaceous earth precursor solution.

[0058] (3) The diatomite precursor solution described in (2) is applied to the cut zinc foil by a casting method, and the solution is allowed to stand naturally for 1 hour until a uniform film is formed on the surface of the zinc metal. The zinc foil coated on one side is placed in an oven and dried at 60° C. for 6 hours to obtain a negative electrode sheet coated with a diatomite artificial protective layer, the protective layer thickness is about 62 μm, and the zinc ion migration number T (Zn 2+ ) is 0.559.

[0059] (4) After drying, the zinc metal anode coated with a diatomaceous earth protective layer was assembled into a symmetrical battery at 1 mA cm -2 , 1mAhcm -2 The lifespan can reach 900h under the current density. The negative electrode sheet coated with diatomite artificial protective layer and the positive electrode material V2O5 are assembled into a zinc metal battery in 2MZnSO4 electrolyte. The charge and discharge test is carried out under the condition of 3A / g high current density. After 1000 cycles, the capacity retention rate is 71%.

[0060] Example 5

[0061] The following steps are involved:

[0062] (1) 0.2 g of diatomaceous earth was calcined at 550° C. for 3 h, and then added to 25 mL of 2.5 mol / L sodium hydroxide solution and soaked at 80° C. for 6 h. The soaked diatomaceous earth was calcined again at 300° C. for 1 h to obtain the treated diatomaceous earth.

[0063] (2) The treated diatomaceous earth described in (1) was added to 5 g of N-methyl-pyrrolidone solution and stirred at 800 r / min for 8 h to obtain a uniform and stable diatomaceous earth precursor solution.

[0064] (3) The diatomite precursor solution described in (2) is applied to the cut zinc foil by a casting method, and the solution is allowed to stand naturally for 1 hour until a uniform film is formed on the surface of the zinc metal. The zinc foil coated on one side is placed in an oven and dried at 60° C. for 6 hours to obtain a negative electrode sheet coated with a diatomite artificial protective layer, wherein the protective layer thickness is about 62.5 μm and the zinc ion migration number T (Zn 2+ ) is 0.566.

[0065] (4) After drying, the zinc metal anode coated with a diatomaceous earth protective layer was assembled into a symmetrical battery at 2 mA cm -2 , 1mAhcm -2 The lifespan can reach 970h under the current density. The negative electrode sheet coated with diatomite artificial protective layer and the positive electrode material V2O5 were assembled into a zinc metal battery in 2MZnSO4 electrolyte. The charge and discharge test was carried out under the condition of 5A / g current density. After 1000 cycles, the capacity retention rate was 80.8%.

[0066] Example 6

[0067] The following steps are involved:

[0068] (1) 0.2 g of diatomaceous earth was calcined at 450°C for 3 h, and then added to 25 mL of 5 mol / L ammonia solution and soaked at 80°C for 6 h. The soaked diatomaceous earth was calcined again at 300°C for 1 h to obtain the treated diatomaceous earth.

[0069] (2) The treated diatomaceous earth described in (1) was added to 4.9 g of N-methyl-pyrrolidone solution and stirred at 800 r / min for 6 h to obtain a uniform and stable diatomaceous earth precursor solution.

[0070] (3) The diatomite precursor solution described in (2) was applied to the cut zinc foil by a casting method, and the solution was allowed to stand naturally for 1 hour until a uniform film was formed on the surface of the zinc metal. The zinc foil coated on one side was placed in an oven and dried at 60° C. for 6 hours to obtain a negative electrode sheet coated with a diatomite artificial protective layer, the protective layer thickness of which was about 61.5 μm, and the zinc ion migration number T (Zn 2+ ) is 0.524.

[0071] (4) After drying, the zinc metal anode coated with a diatomaceous earth protective layer was assembled into a symmetrical battery at 4 mA cm -2 , 1mAhcm -2The lifespan can reach 1300h under the current density. The negative electrode sheet coated with diatomite artificial protective layer and the positive electrode material V2O5 were assembled into a zinc metal battery in 2MZnSO4 electrolyte. The charge and discharge test was carried out under the condition of 4A / g current density. After 1000 cycles, the capacity retention rate was 80.2%.

[0072] In summary, the present invention has the following advantages:

[0073] (1) The zinc metal battery negative electrode with a multifunctional protective layer of the present invention is prepared using cheap diatomaceous earth as a main raw material. The diatomaceous earth is coated on a zinc foil by a simple tape casting method to prepare a zinc metal battery negative electrode with a multifunctional protective layer. The preparation cost is low and can be prepared on a large scale.

[0074] (2) The zinc metal battery negative electrode with a multifunctional protective layer of the present invention is functionalized in that the protective layer can not only guide the deposition process of zinc ions due to its porous structure and selective ion channels, thereby achieving uniform deposition of zinc ions and avoiding dendrites, but also because the artificial protective layer isolates the zinc metal negative electrode from direct contact with the electrolyte, thereby inhibiting the corrosion of the zinc negative electrode and the generation of hydrogen evolution. More importantly, diatomaceous earth has a large number of Si-OH bonds, which will undergo protonation effect in the electrolyte to produce a large amount of Si-OH2 + , so that the protective layer has a strong positive charge and changes the anode interface environment. At the same time, it also causes a large number of anions in the electrolyte to be fixed in the outer layer, promoting the desolvation process and further reducing side reactions. The multifunctional artificial protective layer is also rich in Si-O bonds and -OH bonds, which can form hydrogen bonds with water molecules in the electrolyte, thereby inhibiting the activity of water, reducing side reactions and corrosion, and accelerating the Zn 2+ Therefore, the electrochemical performance of the battery can be further improved.

[0075] What is disclosed above is only one or more preferred embodiments of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of implementing the above embodiments and making equivalent changes according to the claims of the present invention still fall within the scope of the invention.

Claims

1. A method for preparing a zinc metal battery negative electrode with a multifunctional protective layer, characterized in that: The following steps are involved: Step 1: calcining diatomite at high temperature, soaking the calcined diatomite in an alkaline solution, and then calcining the pretreated diatomite at high temperature for a second time; Step 2: adding the treated diatomaceous earth into the N-methyl-pyrrolidone solution and fully stirring with the polyvinylidene fluoride to obtain a mixture slurry; Step 3: coating the mixture slurry onto a zinc foil by a tape casting method and drying the mixture to obtain a negative electrode of a zinc metal battery.

2. The method for preparing a negative electrode of a zinc metal battery having a multifunctional protective layer according to claim 1, characterized in that: The alkaline solution is one or more of sodium hydroxide, potassium hydroxide and ammonia water, and the concentration is 1 mol / L-5 mol / L.

3. The method for preparing a negative electrode of a zinc metal battery having a multifunctional protective layer according to claim 2, characterized in that: In step 1, the high temperature calcination temperature is 350-550°C and the time is 1-3h; the immersion temperature of the alkaline solution is 50-85°C and the time is 2-8h; the secondary high temperature calcination temperature is 250-350°C and the time is 1-3h.

4. The method for preparing a negative electrode of a zinc metal battery having a multifunctional protective layer according to claim 3, characterized in that: The mass ratio of the alkaline solution, the N-methyl-pyrrolidone, the polyvinylidene fluoride and the diatomaceous earth in step 2 is 20-25 g: 4-5 g: 0.06-0.2 g: 0.6-2 g.

5. The method for preparing a negative electrode of a zinc metal battery having a multifunctional protective layer according to claim 4, characterized in that: In step 2, the stirring rate is 800 r / min and the time is 6-8 h.

6. The method for preparing a negative electrode of a zinc metal battery having a multifunctional protective layer according to claim 5, characterized in that: The execution process of step 3 is specifically to apply the mixed slurry to a single side of the zinc foil by a casting method, let it stand naturally for 1 hour, build a skeleton of the protective layer on the zinc foil, put the zinc foil coated with the protective layer into an oven, and dry it at 60°C for 8 hours to obtain the zinc metal battery negative electrode.

7. A zinc metal battery with a multifunctional protective layer, wherein the negative electrode is prepared using the method for preparing a zinc metal battery negative electrode with a multifunctional protective layer as claimed in claim 6, characterized in that: It also includes a positive electrode, wherein the positive electrode material includes at least one of a manganese-based material, a vanadium-based material, a sulfide, a selenide, and a Prussian blue analogue.

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