A zinc metal battery with a multifunctional protective layer and a method for preparing its negative electrode.

Abstract

This invention relates to the field of metal battery technology, specifically to a zinc metal battery with a multifunctional protective layer and its negative electrode preparation method. First, natural diatomaceous earth is calcined at high temperature. The calcined diatomaceous earth is then soaked in an alkaline solution and calcined again. Next, an N-methylpyrrolidone (NMP) solution is added and thoroughly stirred with polyvinylidene fluoride (PVDF) to obtain a slurry mixture. Finally, the slurry is coated onto zinc foil using a casting method and dried to obtain the zinc metal battery negative electrode. The zinc metal battery negative electrode of this invention achieves uniform zinc ion deposition due to the porous structure and selective ion channels of the protective layer itself. More importantly, the protonation effect of diatomaceous earth in a weakly acidic electrolyte environment regulates the microenvironment around the zinc negative electrode, further reducing dendrite formation and side reactions, thus improving the battery's cycle life. Furthermore, the preparation process is simple, low-cost, and suitable for large-scale production.

Description

Technical Field

[0001] This invention relates to the field of metal battery technology, specifically to a zinc metal battery with a multifunctional protective layer and a method for preparing its negative electrode. Background Technology

[0002] During the charging and discharging process, zinc metal batteries are prone to zinc dendrite growth, zinc metal corrosion, and hydrogen evolution on the negative electrode zinc metal surface, which can lead to problems such as battery short circuit, battery swelling and failure, poor reversibility, and low cycle life.

[0003] To address the above issues, constructing an artificial zinc anode protective layer is considered the most direct, simplest, and most practical method. Among various protective layer materials, inorganic natural mineral materials have attracted widespread attention due to their abundant reserves, low cost, and environmental friendliness. For example, Kang et al. coated the zinc anode surface with porous nano-CaCO3, utilizing the porous characteristics of the coating layer to guide the deposition of zinc ions during the electrochemical reaction, thereby reducing dendrite formation. Simultaneously, the isolation effect of the CaCO3 layer reduces the contact between zinc and the electrolyte, thus minimizing zinc corrosion and hydrogen evolution reaction, thereby improving battery performance. Similarly, previous researchers have used natural inorganic mineral materials such as kaolin and montmorillonite as protective layers for zinc anode protection.

[0004] However, existing inorganic natural mineral material protective layers only achieve physical regulation through the material's own structure, which may lose stability during battery cycling, leading to a weakening of the protective effect. Furthermore, the complex and costly preparation processes often limit their widespread adoption in practical applications. Summary of the Invention

[0005] The purpose of this invention is to provide a zinc metal battery with a multifunctional protective layer and a method for preparing its negative electrode. The aim is to design a zinc metal battery with a multifunctional protective layer that suppresses dendrite growth through its own structure and suppresses internal side reactions and is corrosion resistant by adjusting the interface environment.

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

[0007] Step 1: Calcining the diatomaceous earth at high temperature, soaking the calcined diatomaceous earth in an alkaline solution, and then calcining the pretreated diatomaceous earth at high temperature a second time.

[0008] Step 2: Add the treated diatomaceous earth to the N-methyl-pyrrolidone solution and stir thoroughly with polyvinylidene fluoride to obtain a slurry mixture;

[0009] Step 3: The mixture slurry is coated onto zinc foil by casting and then dried to obtain the zinc metal battery negative electrode.

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

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

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

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

[0014] Optionally, step 3 involves coating the mixed slurry onto one side of a zinc foil using a casting method, allowing it to stand naturally for 1 hour, and then placing the zinc foil coated with the protective layer into an oven to dry 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. The negative electrode is prepared using the method for preparing a zinc metal battery negative electrode with a multifunctional protective layer, and the battery also includes a positive electrode. The positive electrode material includes at least one of manganese-based, vanadium-based, sulfide, selenide, and Prussian blue analogues.

[0016] This invention provides a zinc metal battery with a multifunctional protective layer and a method for preparing its negative electrode. Diatomaceous earth is calcined at high temperature, then soaked in an alkaline solution, and subsequently calcined a second time to obtain treated diatomaceous earth. This treated diatomaceous earth is then added to an N-methyl-pyrrolidone solution and thoroughly stirred with polyvinylidene fluoride to obtain a slurry. This slurry is then coated onto zinc foil using a casting method and dried at a constant temperature to obtain the zinc metal battery negative electrode. The zinc metal battery negative electrode, due to the porous structure and selective ion channels of its protective layer, can guide the zinc ion deposition process, achieving uniform zinc ion deposition and preventing dendrite formation. Furthermore, because the artificial protective layer isolates the zinc metal negative electrode from direct contact with the electrolyte, it inhibits corrosion and hydrogen evolution. More importantly, the numerous Si-OH bonds in diatomaceous earth undergo protonation in the electrolyte, generating a large amount of Si-OH2. +This results in a protective layer carrying a strong positive charge, altering the anodic interface environment. This leads to a large number of anions in the electrolyte being fixed in the outer electrode layer, promoting the desolvation process and further reducing side reactions. This multifunctional artificial protective layer is also rich in Si-O and -OH bonds, which can form hydrogen bonds with water molecules in the electrolyte, thereby inhibiting water activity, reducing side reactions and corrosion, and accelerating Zn... 2+ Migration. Therefore, the electrochemical performance of the battery can be further improved. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic flowchart of the steps involved in the preparation of a zinc metal battery with a multifunctional protective layer and its negative electrode according to the present invention.

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

[0020] Figure 3 This 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 This is a SEM image of the cross-section of the zinc metal battery negative electrode with a multifunctional protective layer in a specific embodiment of the present invention.

[0022] Figure 5 This is a specific embodiment of the present invention at 8mA cm -2 1mAh cm -2 Graph of long-term cycle test of symmetrical battery under current density.

[0023] Figure 6 This is a full-cell 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 Implementation

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

[0025] Please see Figure 1 This invention provides a zinc metal battery with a multifunctional protective layer and a method for preparing the negative electrode thereon, comprising the following steps:

[0026] S1: The diatomaceous earth is calcined at high temperature, and the calcined diatomaceous earth is soaked in an alkaline solution. Then the pretreated diatomaceous earth is calcined at high temperature again.

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

[0028] S3: The mixture slurry is coated onto zinc foil by casting and then dried to obtain a zinc metal battery negative electrode.

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

[0030] In step S2, the stirring speed is 800 r / min, and the stirring time is 6-8 h. 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 onto one side of the zinc foil by casting, and allowed to stand naturally for 1 hour. After constructing the framework 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 the zinc metal battery negative electrode.

[0032] Zinc metal battery anodes possess uniform selective ion channels, and the protective layer thickness is controllable, ranging from approximately 55 μm to 65 μm. Zinc metal battery anodes are rich in various functional groups, such as zinc-philic Si-OH bonds and Si-O bonds.

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

[0034] Please see Figures 2 to 6 The following detailed description of the method for preparing the zinc metal battery anode with a multifunctional protective layer is provided in conjunction with specific embodiments:

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

[0036] Example 1

[0037] Includes the following steps:

[0038] (1) 0.2 g of diatomaceous earth was calcined at 350 °C for 2 h, 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 then calcined again at 250 °C for 1 h. The treated diatomaceous earth was obtained.

[0039] (2) Add the diatomaceous earth treated in (1) to 4.6g of N-methyl-pyrrolidone solution and stir at 800r / min for 6h to obtain a homogeneous and stable diatomaceous earth precursor solution.

[0040] (3) The diatomaceous earth precursor solution described in (2) is coated onto the cut zinc foil using a casting method. The foil is allowed to stand naturally for 1 hour to form a uniform film on the zinc metal surface. The zinc sheet with the single-sided coating is then placed in an oven and dried at 60°C for 6 hours to obtain a negative electrode sheet coated with a diatomaceous earth artificial protective layer. Scanning electron micrographs of the diatomaceous earth protective layer and the zinc metal surface are shown below. Figure 3 (a) SEM image of the zinc metal battery anode with a multifunctional protective layer; (b) SEM image of the bare zinc surface. The protective layer is approximately 58 μm thick, and its cross-sectional SEM image is shown below. Figure 4 Zinc ion transport number T(Zn) 2+ The value is 0.6.

[0041] (4) A symmetrical battery was assembled with a zinc metal negative electrode coated with a diatomaceous earth protective layer after drying, and then tested at 8 mA cm⁻¹. -2 1mAhcm -2 At current density, the lifetime can reach 2400 hours, as shown in the results. Figure 5 The negative electrode sheet coated with an artificial protective layer of diatomaceous earth and the positive electrode material Na2V6O 16 • 1.5H₂O (NVO) was used to assemble a zinc metal battery in a 2M ZnSO₄ electrolyte. Charge-discharge tests were conducted at a current density of 1 A / g, and the capacity retention rate was 90% after 800 cycles. The results are shown in [Figure number missing]. Figure 6 .

[0042] Example 2

[0043] Includes the following steps:

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

[0045] (2) Add the diatomaceous earth treated in (1) to 4.2g of N-methyl-pyrrolidone solution and stir at 800r / min for 7h to obtain a homogeneous and stable diatomaceous earth precursor solution.

[0046] (3) The diatomaceous earth precursor solution described in (2) is coated onto the cut zinc foil using a casting method. After standing naturally for 1 hour to form a uniform film on the zinc metal surface, the zinc foil with the single-sided coating is placed in an oven and dried at 60°C for 6 hours to obtain a negative electrode sheet coated with a diatomaceous earth artificial protective layer. The protective layer thickness is approximately 68 μm, and the zinc ion transference number T(Zn) is... 2+ The value is 0.51.

[0047] (4) A symmetrical battery was assembled with a zinc metal negative electrode coated with a diatomaceous earth protective layer after drying, and tested at 6 mA cm⁻¹. -2 1mAhcm -2 At current density, the battery has a lifespan of up to 1400 hours. The negative electrode coated with diatomaceous earth artificial protective layer and the positive electrode material MnO2 are assembled into a zinc metal battery in 2MZnSO4 electrolyte. Under the condition of 2A / g current density, the capacity retention rate is 88% after 2000 cycles.

[0048] Example 3

[0049] Includes the following steps:

[0050] (1) 0.2 g of diatomaceous earth was calcined at 450 °C for 2 h, 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 then calcined again at 300 °C for 1 h. The treated diatomaceous earth was obtained.

[0051] (2) Add the diatomaceous earth treated in (1) to 4g of N-methyl-pyrrolidone solution and stir at 800r / min for 8h to obtain a homogeneous and stable diatomaceous earth precursor solution.

[0052] (3) The diatomaceous earth precursor solution described in (2) is coated onto the cut zinc foil using a casting method. After standing naturally for 1 hour to form a uniform film on the zinc metal surface, the zinc sheet with the single-sided coating is placed in an oven and dried at 60°C for 6 hours to obtain a negative electrode sheet coated with a diatomaceous earth artificial protective layer. The thickness of the protective layer is approximately 62.8 μm, and the zinc ion transference number T(Zn) is [not specified]. 2+ The value is 0.558.

[0053] (4) A symmetrical battery was assembled with a zinc metal negative electrode coated with a diatomaceous earth protective layer after drying, and tested at 10 mA cm⁻¹. -2 1mAh cm -2 At current density, the lifespan can reach 1200 hours. A negative electrode coated with a diatomaceous earth artificial protective layer and a positive electrode material V2O5 are assembled into a zinc metal battery in 2M ZnSO4 electrolyte. Under charge-discharge testing at a current density of 1A / g, the capacity retention rate is 61% after 1000 cycles.

[0054] Example 4

[0055] Includes the following steps:

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

[0057] (2) Add the diatomaceous earth treated in (1) to 4.5g of N-methyl-pyrrolidone solution and stir at 800r / min for 6h to obtain a homogeneous and stable diatomaceous earth precursor solution.

[0058] (3) The diatomaceous earth precursor solution described in (2) is coated onto the cut zinc foil using a casting method. The foil is allowed to stand naturally for 1 hour to form a uniform film on the zinc metal surface. The zinc sheet with the single-sided coating is then placed in an oven and dried at 60°C for 6 hours to obtain a negative electrode sheet coated with a diatomaceous earth artificial protective layer. The protective layer thickness is approximately 62 μm, and the zinc ion transport number T(Zn) is [not specified]. 2+ The value is 0.559.

[0059] (4) A symmetrical battery was assembled with a zinc metal negative electrode coated with a diatomaceous earth protective layer after drying, and tested at 1 mA cm⁻¹. -2 1mAhcm -2 At current density, the lifespan can reach 900 hours. A negative electrode coated with a diatomaceous earth artificial protective layer and a positive electrode material V2O5 are assembled into a zinc metal battery in a 2M ZnSO4 electrolyte. Under a high current density of 3A / g, the capacity retention rate is 71% after 1000 cycles.

[0060] Example 5

[0061] Includes the following steps:

[0062] (1) 0.2 g of diatomaceous earth was calcined at 550 °C for 3 h, 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 then calcined again at 300 °C for 1 h. The treated diatomaceous earth was obtained.

[0063] (2) Add the diatomaceous earth treated in (1) to 5g of N-methyl-pyrrolidone solution and stir at 800r / min for 8h to obtain a homogeneous and stable diatomaceous earth precursor solution.

[0064] (3) The diatomaceous earth precursor solution described in (2) is coated onto the cut zinc foil using a casting method. The foil is allowed to stand naturally for 1 hour to form a uniform film on the zinc metal surface. The zinc foil with the single-sided coating is then placed in an oven and dried at 60°C for 6 hours to obtain a negative electrode sheet coated with a diatomaceous earth artificial protective layer. The thickness of the protective layer is approximately 62.5 μm, and the zinc ion transference number T(Zn) is [not specified]. 2+ The value is 0.566.

[0065] (4) A symmetrical battery was assembled with a zinc metal negative electrode coated with a diatomaceous earth protective layer after drying, and tested at 2 mA cm⁻¹. -2 1mAhcm -2 At current density, the lifespan can reach 970 hours. A negative electrode coated with a diatomaceous earth artificial protective layer and a positive electrode material V2O5 are assembled into a zinc metal battery in a 2M ZnSO4 electrolyte. Under charge-discharge testing at a current density of 5A / g, the capacity retention rate is 80.8% after 1000 cycles.

[0066] Example 6

[0067] Includes the following steps:

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

[0069] (2) Add the diatomaceous earth treated in (1) to a 4.9 g N-methyl-pyrrolidone solution and stir at 800 r / min for 6 h to obtain a homogeneous and stable diatomaceous earth precursor solution.

[0070] (3) The diatomaceous earth precursor solution described in (2) is coated onto the cut zinc foil using a casting method. After standing naturally for 1 hour, a uniform film is formed on the zinc metal surface. The zinc sheet with the single-sided coating is placed in an oven and dried at 60°C for 6 hours to obtain a negative electrode sheet coated with a diatomaceous earth artificial protective layer. The thickness of the protective layer is approximately 61.5 μm, and the zinc ion transference number T(Zn) is [not specified]. 2+ The value is 0.524.

[0071] (4) A symmetrical battery was assembled with a zinc metal negative electrode coated with a diatomaceous earth protective layer after drying, and tested at 4 mA cm⁻¹. -2 1mAhcm -2At current density, the lifespan can reach 1300 hours. A negative electrode coated with a diatomaceous earth artificial protective layer and a positive electrode material V2O5 are assembled into a zinc metal battery in a 2M ZnSO4 electrolyte. Under charge-discharge testing at a current density of 4A / g, the capacity retention rate is 80.2% after 1000 cycles.

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

[0073] (1) The zinc metal battery anode with a multifunctional protective layer of the present invention is prepared using inexpensive diatomaceous earth as the main raw material. The zinc metal battery anode with a multifunctional protective layer can be prepared by coating the diatomaceous earth onto zinc foil through a simple casting method. The preparation cost is low and it can be prepared on a large scale.

[0074] (2) The zinc metal battery anode with a multifunctional protective layer of the present invention is functionalized in that the protective layer not only guides the zinc ion deposition process due to its porous structure and selective ion channels, achieving uniform zinc ion deposition and avoiding dendrite formation, but also, because the artificial protective layer isolates the zinc metal anode from direct contact with the electrolyte, inhibiting the corrosion of the zinc anode 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 generate a large amount of Si-OH2. + This results in a protective layer carrying a strong positive charge, altering the anodic interface environment. Simultaneously, it causes a large number of anions from the electrolyte to be fixed in the outer electrode layer, promoting the desolvation process and further reducing side reactions. This multifunctional artificial protective layer is also rich in Si-O and -OH bonds, which can form hydrogen bonds with water molecules in the electrolyte, thereby inhibiting water activity, reducing side reactions and corrosion, and accelerating Zn... 2+ Migration. Therefore, the electrochemical performance of the battery can be further improved.

[0075] The above description discloses only one or more preferred embodiments of the present invention, and should not be construed as limiting the scope of the present invention. Those skilled in the art will understand that all or part of the processes of the above embodiments can be implemented, and equivalent changes made in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A method for preparing a zinc metal battery anode with a multifunctional protective layer, characterized in that, The method comprises the following steps: Step 1: high-temperature calcination of diatomite, soaking of the calcined diatomite in an alkali solution, and secondary high-temperature calcination of the pretreated diatomite; Step 2: adding the treated diatomite into an N-methyl-pyrrolidone solution and fully stirring with polyvinylidene fluoride to obtain a mixture slurry; Step 3: coating the mixture slurry onto a zinc foil by a flow casting method and drying to obtain a zinc metal battery negative electrode.

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

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

4. The method for preparing a zinc metal battery negative electrode with a multifunctional protective layer according to claim 3, wherein the mass ratio of the alkali solution, the N-methyl-pyrrolidone, the polyvinylidene fluoride and the diatomite 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 zinc metal battery negative electrode with a multifunctional protective layer according to claim 4, wherein the stirring rate in step 2 is 800 r / min, and the time is 6-8 h.

6. The method for preparing a zinc metal battery negative electrode with a multifunctional protective layer according to claim 5, wherein the execution process of step 3 is that the mixture slurry is coated onto one side of the zinc foil by a flow casting method, and is naturally placed for 1 h, and after the skeleton of the protective layer is constructed on the zinc foil, the zinc foil coated with the protective layer is placed into an oven, and is dried at 60°C for 8 h to obtain a zinc metal battery negative electrode.

7. A zinc metal battery with a multifunctional protective layer, wherein the negative electrode is prepared by the method for preparing a zinc metal battery negative electrode with a multifunctional protective layer according to claim 6, and the zinc metal battery further comprises a positive electrode, and the positive electrode material comprises at least one of manganese-based, vanadium-based, sulfide, selenide and Prussian blue analogues. ​ ​ ​ ​ ​ ​

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