Protective layer for metal negative electrode of aqueous zinc ion battery and preparation method and application of protective layer

Abstract

The invention discloses a protective layer of a metal negative electrode of an aqueous zinc ion battery and a preparation method and application of the protective layer, and the protective layer of the metal negative electrode of the aqueous zinc ion battery comprises the following raw materials in percentage by weight: 90-95% of an active material and 5-10% of a binder. The surface of the zinc metal negative electrode is covered with a uniform and cheap porous induced zinc ion uniform deposition protection layer, and the protection layer can be coupled with active water molecules through a specific PVP / PANI nitrogen-containing conjugated skeleton, electrostatic coupling Zn < 2 + > and side chain loaded active polar groups (-NH <-> and = N <->), so that the desolvation efficiency is improved, the corrosion of water to zinc is inhibited, and the service life of the zinc metal negative electrode is prolonged. Meanwhile, zinc ions are guided to be uniformly deposited, the activity of the zinc ions is regulated and controlled, the growth of zinc dendrites is inhibited, the electrochemical performance of the battery is effectively improved, and the cycle life of the battery is effectively prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of aqueous zinc ion batteries, and in particular relates to a protective layer of a metal negative electrode of an aqueous zinc ion battery, and a preparation method and application thereof. Background Art

[0002] Aqueous zinc-ion batteries are relatively simple to manufacture and maintain, and zinc resources are abundant. Their cost is lower than that of lithium batteries, which makes them have greater application potential in large-scale energy storage. Aqueous zinc-ion batteries use water as the electrolyte solvent, avoiding the safety hazards brought by the highly flammable organic electrolyte in lithium batteries, and have higher safety and environmental protection. -1 ) with different positive electrode materials, such as manganese materials (manganese dioxide), vanadium materials (vanadium pentoxide), Prussian blue analogs, organic compounds, halogen elements, etc., aqueous zinc-ion batteries can meet different practical application needs. However, due to the uneven deposition / stripping behavior of zinc ions during the cycle, the negative electrode of this type of battery often has dendrite growth and severe hydrogen evolution reaction corrosion electrode, which affects the battery life and causes the battery performance to decline rapidly.

[0003] One of the effective ways to achieve a highly stable zinc negative electrode is to construct a functional coating on the zinc surface. Chinese patent application CN114005949A discloses a zinc battery negative electrode protected by a hydrophobic layer, a preparation method and a battery. A layer of titanate and a hydrophobic binder mixture is provided on the surface of the zinc battery negative electrode active material as a zinc negative electrode protective layer. The protective layer has a certain hydrophobicity and a stable structure. It can effectively inhibit hydrogen evolution at the zinc negative electrode and can also inhibit zinc dendrites. The zinc negative electrode provided with the hydrophobic protective layer and the battery using the negative electrode can significantly improve the charge and discharge cycle performance. Chinese patent application CN115312685A discloses a protective layer for a metal zinc negative electrode of an aqueous zinc ion battery and a preparation method for the metal zinc negative electrode. The raw material composition of the protective layer is mainly 70-90% of active material, 5-15% of conductive agent and 5-15% of binder, expressed in weight percentage. The weighed active material, conductive agent and binder are ground and mixed, and N-methylpyrrolidone or distilled water is added after mixing and stirred evenly to obtain a protective coating slurry; the obtained coating slurry is evenly coated on the metal zinc negative electrode, and then the film is scraped, dried, rolled and cut in sequence to obtain a new type of coating-protected aqueous zinc ion battery metal zinc negative electrode. The invention uses cheap cation exchange materials as the active material of the metal zinc negative electrode protective layer to inhibit the growth and corrosion passivation of the metal zinc negative electrode dendrites during the charge and discharge process of the zinc ion battery, thereby greatly improving the battery's cycle stability and electrochemical performance. Although the above method solves the zinc negative electrode problem to a certain extent, it still has problems such as complex preparation process, high cost, by-product pollution of the environment and high energy consumption (such as the use of heavy metal salts and high-temperature calcination), which is not conducive to the further industrialization of aqueous zinc ion batteries.

[0004] Therefore, it is of great practical significance to find a simple, inexpensive, and environmentally friendly material to prepare a functional coating that can simultaneously inhibit zinc negative electrode dendrite growth and electrode corrosion. Summary of the invention

[0005] In view of the deficiencies in the prior art, the object of the present invention is to provide a protective layer for the metal negative electrode of an aqueous zinc ion battery and a preparation method and application thereof, so as to solve the problems of poor stability of the negative electrode of the aqueous zinc ion battery, easy occurrence of dendrite growth and hydrogen evolution corrosion during the cycle process.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A protective layer for a metal negative electrode of an aqueous zinc ion battery. The raw materials of the protective layer are composed of 90-95% active material and 5-10% binder in weight percentage.

[0008] Preferably, a protective layer for a metal negative electrode of an aqueous zinc ion battery comprises, in weight percentage, 90% active material and 10% binder; the active material is PVP / PANI, and the binder is PVDF.

[0009] Preferably, the preparation method of the PVP / PANI is as follows:

[0010] Dissolve PVP in deionized water, then add aniline, stir evenly, then add ammonium persulfate solution, and react under room temperature with stirring. After the reaction is completed, let stand, precipitate, filter, wash, and dry to obtain the product.

[0011] Preferably, the mass concentration of the ammonium persulfate solution is 15-20%, the mass ratio of the PVP, aniline and ammonium persulfate solution is 1-2:0.8-1.2:10-15, and the stirring reaction time is 20-30h.

[0012] Preferably, the thickness of the protective layer is 5-20 μm.

[0013] The present invention also provides an application of the protective layer of the metal negative electrode of an aqueous zinc ion battery as described above in preparing a metal zinc negative electrode of an aqueous zinc ion battery with a protective layer, comprising the following steps:

[0014] S1. preparing active materials;

[0015] S2. Weigh the active material and the binder according to the formula, grind and mix them, then add N-methylpyrrolidone and stir evenly to obtain a protective layer slurry;

[0016] S3, evenly drop the protective layer slurry in step S2 onto the cut metal zinc negative electrode, and dry it to obtain the metal zinc negative electrode of the aqueous zinc ion battery with a protective layer.

[0017] Preferably, in step S2, the N-methylpyrrolidone accounts for 95-98% of the mass of the protective layer slurry.

[0018] Preferably, the metal zinc negative electrode in step S3 is a zinc foil with a thickness of 80-100 μm.

[0019] Preferably, the drying condition in step S3 is: vacuum drying at 80° C. for 1-2 h.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) The present invention uses a simple drop coating method to cover the surface of the zinc metal negative electrode with a uniform and inexpensive uniform deposition protective layer, which can electrostatically couple Zn through its unique nitrogen-containing conjugated skeleton of PVP / PANI. 2+The active polar groups (-NH- and =N-) loaded on the side chains couple with active water molecules, improve the desolvation efficiency, and inhibit the corrosion of zinc by water. At the same time, they guide the uniform deposition of zinc ions, regulate the activity of zinc ions, and inhibit the growth of zinc dendrites, effectively improving the electrochemical performance and cycle life of the battery.

[0022] (2) The protective layer of the metal negative electrode of the aqueous zinc ion battery provided by the present invention uses cheap and easy-to-prepare PVP / PANI as the active material of the zinc negative electrode protective layer. PVP / PANI is insoluble in water and can work with PVDF to improve the hydrophobicity of the protective layer to prevent water molecules from penetrating the coating, thereby inhibiting the growth and corrosion passivation of the metal zinc negative electrode dendrites during the charge and discharge process of the zinc ion battery, thereby greatly improving the cycle stability and electrochemical performance of the battery, so that the prepared aqueous zinc battery has a long cycle life and stable performance.

[0023] (3) The protective layer of the metal negative electrode of the aqueous zinc ion battery provided by the present invention adopts PANI, which has a broad industrial base, is rich in resources, low in price and environmentally friendly, and can meet the requirements of large-scale production. At the same time, the concept of using PVP / PANI as the protective layer of the metal zinc negative electrode of the aqueous zinc ion battery is proposed. Only by coating PVP / PANI on the surface of the zinc negative electrode, a zinc negative electrode with excellent stability can be obtained, thereby realizing a high-performance aqueous zinc battery.

[0024] (4) The aqueous zinc battery prepared by the technical solution of the present invention is safe and reliable. The zinc symmetric battery prepared by chemical method has an output current of 1 mA cm -2 (1mAh cm -2 ) current density can reach 1000h; the zinc-manganese full battery prepared by the method can achieve a cycle life of 1000h at 1Ag -1 The current density (calculated based on the active material) can be maintained for more than 700 cycles with a capacity retention rate of up to 80%.

[0025] (5) The protective layer of the metal negative electrode of the aqueous zinc ion battery provided by the present invention uses PVDF as a binder to produce a film with a certain hydrophobicity, which can repel contact with water molecules, thereby further improving the protection of the zinc negative electrode; the negative electrode protective layer is prepared by a drop coating method. Compared with the scraping method, the drop coating method can obtain a thinner coating, increase the proportion of metal zinc in the electrode, and improve the energy density of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The button-type symmetrical cell prepared for the aqueous zinc ion battery metal zinc negative electrode of Example 1 was charged at a constant current density of 1 mA cm -2 , constant capacity 1mAh cm -2 The time-voltage diagram below.

[0027] Figure 2The button-type full cell prepared for the aqueous zinc ion battery metal zinc negative electrode of Example 1 is 1Ag -1 Cycling performance diagram under constant current density.

[0028] Figure 3 This is a diagram of the discharge specific capacity of a button-type full cell prepared with the metal zinc negative electrode of the aqueous zinc ion battery of Example 1 at different times.

[0029] Figure 4 The button-type symmetrical battery prepared for the aqueous zinc ion battery metal zinc negative electrode of Example 1 and Comparative Example 1 was 1Ag -1 Cycling performance diagram under constant current density.

[0030] Figure 5 The button-type symmetrical battery prepared for the aqueous zinc ion battery metal zinc negative electrode of Example 1 and Comparative Example 2 was 1Ag -1 Cycling performance diagram under constant current density. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Example 1

[0033] The invention discloses a protective layer for a metal negative electrode of an aqueous zinc ion battery, which consists of 90% PVP / PANI and 10% PVDF by weight.

[0034] The preparation method of PVP / PANI is as follows: 1.1g PVP is dissolved in 30g deionized water, then 0.93g aniline is added, and after stirring evenly, 10g ammonium persulfate solution with a mass concentration of 18.6% is added, and the reaction is stirred at room temperature for 24h. After the reaction is completed, the solution is allowed to stand for precipitation, filtered, washed, and dried to obtain PVP / PANI.

[0035] A method for preparing a metal zinc negative electrode of an aqueous zinc ion battery with a protective layer for a metal negative electrode of an aqueous zinc ion battery comprises the following steps:

[0036] S1. Preparation of PVP / PANI;

[0037] S2. Grind and mix PVP / PANI and PVDF according to the above formula, then add N-methylpyrrolidone and stir evenly to obtain a protective layer slurry; the N-methylpyrrolidone accounts for 98% of the mass of the protective layer slurry;

[0038] S3, evenly drop the protective layer slurry in step S2 on the cut zinc foil negative electrode with a thickness of 90 μm, and vacuum dry it at 80° C. for 1.5 h to obtain a metal zinc negative electrode for an aqueous zinc ion battery with a protective layer (thickness of 10 μm).

[0039] Example 2

[0040] The invention discloses a protective layer for a metal negative electrode of an aqueous zinc ion battery, which consists of 93% of PVP / PANI and 7% of PVDF by weight.

[0041] The preparation method of PVP / PANI is as follows: 2g PVP is dissolved in 30g deionized water, then 1.5g aniline is added, and after stirring evenly, 15g ammonium persulfate solution with a mass concentration of 18.6% is added, and the reaction is stirred at room temperature for 30h. After the reaction is completed, the solution is allowed to stand for precipitation, filtered, washed, and dried to obtain PVP / PANI.

[0042] A method for preparing a metal zinc negative electrode of an aqueous zinc ion battery with a protective layer for a metal negative electrode of an aqueous zinc ion battery comprises the following steps:

[0043] S1. Preparation of PVP / PANI;

[0044] S2. PVP / PANI and PVDF are ground and mixed according to the above formula, and then N-methylpyrrolidone is added and stirred evenly to obtain a protective layer slurry; the N-methylpyrrolidone accounts for 96% of the mass of the protective layer slurry;

[0045] S3, evenly drop the protective layer slurry in step S2 on the cut zinc foil negative electrode with a thickness of 100 μm, and vacuum dry it at 80° C. for 1 h to obtain a metal zinc negative electrode for an aqueous zinc ion battery with a protective layer (thickness of 20 μm).

[0046] Example 3

[0047] The invention discloses a protective layer for a metal negative electrode of an aqueous zinc ion battery, which consists of 95% of PVP / PANI and 5% of PVDF by weight.

[0048] The preparation method of PVP / PANI is as follows: 1g PVP is dissolved in 30g deionized water, then 0.8g aniline is added, and after stirring evenly, 10g ammonium persulfate solution with a mass concentration of 18.6% is added, and the reaction is stirred at room temperature for 20h. After the reaction is completed, the solution is allowed to stand for precipitation, filtered, washed, and dried to obtain PVP / PANI.

[0049] A method for preparing a metal zinc negative electrode of an aqueous zinc ion battery with a protective layer for a metal negative electrode of an aqueous zinc ion battery comprises the following steps:

[0050] S1. Preparation of PVP / PANI;

[0051] S2. PVP / PANI and PVDF are ground and mixed according to the above formula, and then N-methylpyrrolidone is added and stirred evenly to obtain a protective layer slurry; the N-methylpyrrolidone accounts for 95% of the mass of the protective layer slurry;

[0052] S3. Evenly drop the protective layer slurry in step S2 onto the cut zinc foil negative electrode with a thickness of 80 μm, and vacuum dry it at 80° C. for 2 h to obtain a metal zinc negative electrode for an aqueous zinc ion battery with a protective layer (thickness of 5 μm).

[0053] Comparative Example 1

[0054] The invention discloses a protective layer for a metal negative electrode of an aqueous zinc ion battery, which consists of 90% of PVP / PANI and 10% of sodium hydroxymethyl cellulose by weight.

[0055] The preparation method of PVP / PANI is as follows: 1.1g PVP is dissolved in 30g deionized water, then 0.93g aniline is added, and after stirring evenly, 10g ammonium persulfate solution with a mass concentration of 18.6% is added, and the reaction is stirred at room temperature for 24h. After the reaction is completed, the solution is allowed to stand for precipitation, filtered, washed, and dried to obtain PVP / PANI.

[0056] A method for preparing a metal zinc negative electrode of an aqueous zinc ion battery with a protective layer for a metal negative electrode of an aqueous zinc ion battery comprises the following steps:

[0057] S1. Preparation of PVP / PANI;

[0058] S2. PVP / PANI and sodium hydroxymethyl cellulose are ground and mixed according to the above formula, and then N-methyl pyrrolidone is added and stirred evenly to obtain a protective layer slurry; the N-methyl pyrrolidone accounts for 98% of the mass of the protective layer slurry;

[0059] S3, evenly drop the protective layer slurry in step S2 on the cut zinc foil negative electrode with a thickness of 90 μm, and vacuum dry it at 80° C. for 1.5 h to obtain a metal zinc negative electrode for an aqueous zinc ion battery with a protective layer (thickness of 10 μm).

[0060] Comparative Example 2

[0061] The invention discloses a protective layer for a metal negative electrode of an aqueous zinc ion battery, which consists of 90% PVP / PANI and 10% PVDF by weight.

[0062] The preparation method of PVP / PANI is as follows: 1.1g PVP is dissolved in 30g deionized water, then 0.93g aniline is added, and after stirring evenly, 10g ammonium persulfate solution with a mass concentration of 18.6% is added, and the reaction is stirred at room temperature for 24h. After the reaction is completed, the solution is allowed to stand for precipitation, filtered, washed, and dried to obtain PVP / PANI.

[0063] A method for preparing a metal zinc negative electrode of an aqueous zinc ion battery with a protective layer for a metal negative electrode of an aqueous zinc ion battery comprises the following steps:

[0064] S1. Preparation of PVP / PANI;

[0065] S2. Grind and mix PVP / PANI and PVDF according to the above formula, then add N-methylpyrrolidone and stir evenly to obtain a protective layer slurry; the N-methylpyrrolidone accounts for 98% of the mass of the protective layer slurry;

[0066] S3, evenly scrape the protective layer slurry in step S2 onto the cut zinc foil negative electrode with a thickness of 90 μm, and vacuum dry it at 80° C. for 1.5 h to obtain a metal zinc negative electrode for an aqueous zinc ion battery with a protective layer (thickness of 10 μm).

[0067] The metal zinc negative electrode of the aqueous zinc ion battery with a protective layer prepared in Example 1 and Comparative Example 1-2 was made into a button-type symmetrical battery, the positive electrode sheet was the same as the negative electrode, ZnSO 4 The solution was used as the electrolyte. The electrochemical performance test was carried out using a blue electric test system with a constant current density of 1 mA cm -2 , constant capacity 1mAh cm -2 The charge and discharge were carried out at a test temperature of 25°C.

[0068] The metal zinc negative electrode of the aqueous zinc ion battery with a protective layer prepared in Example 1 was made into a button-type full battery, with manganese dioxide as the positive electrode sheet and 2 mol / L Zn SO 4 +0.1mol / L MnSO 4 The mixed solution was used as the electrolyte to assemble a button-type full battery. The electrochemical performance test was carried out using the Blue Electric test system, and the charge and discharge voltage range was 0.8V~1.8V (vs. Zn 2+ / Zn), the test temperature is 25°C. It is used to test the cycle life of the battery under different conditions and the capacity discharge capacity under different current densities.

[0069] The test results show that at a constant current density of 1 mA cm -2 , constant capacity 1mAh cm -2 Under the conditions of charge and discharge, the cycle life of the zinc symmetric battery prepared by the method can reach more than 1100h (such as the attached Figure 1In the charge and discharge range of 0.8V to 1.8V, at 1A g -1 At constant current density, the prepared aqueous zinc ion battery negative electrode material has a discharge capacity of 191 mAh g -1 After 100 cycles, the capacity remains at 145 mAh g -1 (As attached Figure 2 At different rates, the full battery maintains a high discharge capacity (as shown in the attached Figure 3 shown).

[0070] Depend on Figure 4 , Figure 5 It is known that at a constant current density of 1 mA cm -2 , constant capacity 1 mAh cm -2 Under charge and discharge conditions, the PVP / PANI interface protection layer prepared by drop coating method using polyvinylidene fluoride as a binder has better battery cycle performance.

[0071] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A protective layer for a metal negative electrode of an aqueous zinc ion battery, characterized in that: In terms of weight percentage, the raw material composition of the protective layer is 90-95% of active material and 5-10% of binder.

2. The protective layer of the metal negative electrode of the aqueous zinc ion battery according to claim 1, characterized in that: In terms of weight percentage, the raw material composition of the protective layer is 90% active material and 10% binder; the active material is PVP / PANI, and the binder is PVDF.

3. The protective layer of the metal negative electrode of the aqueous zinc ion battery according to claim 2, characterized in that: The preparation method of the PVP / PANI is as follows: PVP is dissolved in deionized water, and then aniline is added. After stirring evenly, ammonium persulfate solution is added and stirred at room temperature for reaction. After the reaction is completed, precipitation, filtration, washing and drying are performed to obtain the product.

4. The protective layer of the metal negative electrode of the aqueous zinc ion battery according to claim 3, characterized in that: The mass concentration of the ammonium persulfate solution is 15-20%, the mass ratio of the PVP, aniline and ammonium persulfate solution is 1-2:0.8-1.2:10-15, and the stirring reaction time is 20-30 hours.

5. The protective layer of the metal negative electrode of the aqueous zinc ion battery according to claim 1, characterized in that: The thickness of the protective layer is 5-20 μm.

6. Use of the protective layer of the metal negative electrode of an aqueous zinc ion battery as claimed in any one of claims 1 to 5 in preparing a metal zinc negative electrode of an aqueous zinc ion battery with a protective layer, characterized in that: The following steps are involved: S1. preparing active materials; S2. Weigh the active material and the binder according to the formula, grind and mix them, then add N-methylpyrrolidone and stir evenly to obtain a protective layer slurry; S3, evenly drop the protective layer slurry in step S2 onto the cut metal zinc negative electrode, and dry it to obtain the metal zinc negative electrode of the aqueous zinc ion battery with a protective layer.

7. The use according to claim 6, characterized in that: In step S2, the N-methylpyrrolidone accounts for 95-98% of the mass of the protective layer slurry.

8. The use according to claim 6, characterized in that: The metal zinc negative electrode in step S3 is a zinc foil with a thickness of 80-100 μm.

9. The use according to claim 6, characterized in that: The drying conditions in step S3 are: vacuum drying at 80° C. for 1-2 h.

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