Preparation method and application of basic copper nitrate coating for inhibiting zinc dendrite growth

Abstract

The present invention relates to the field of aqueous zinc ion batteries. A basic copper nitrate protective layer is coated on the surface of a zinc anode by a simple co-precipitation method. On the one hand, its unique hydrophobic structure prevents H2O molecules in the solution from directly contacting Zn, greatly reducing a series of side reactions caused by H2O corrosion, such as hydrogen evolution and the by-product Zn4(OH)6SO4·xH2O. On the other hand, the uniformly distributed CNO is Zn 2+ Nucleation provides more sites, which makes Zn 2+ During the deposition process, it is evenly deposited on the surface of the negative electrode, effectively reducing the 2+ The "tip effect" caused by uneven deposition resulted in the prepared CNO@Zn anode having a 1600-h service life compared to a pure zinc anode in symmetrical cell tests. In coulombic efficiency tests, the CNO@Zn half-cell assembled with Cu foil achieved 1600 cycles, compared to a bare Zn electrode (190 cycles), with a stable coulombic efficiency of 99.8%. In full cells assembled with an Al-MnO2 cathode, the CNO@Zn exhibited higher capacity retention and service life than a pure zinc anode.

Description

Technical Field

[0001] The invention relates to an aqueous zinc ion battery negative electrode material, a preparation method and a zinc ion battery, and belongs to the technical field of electrochemical energy. Background Art

[0002] The deposition of Zn during the charge and discharge process of aqueous zinc-ion batteries leads to a "tip effect," which deteriorates the reversibility of aqueous zinc-ion batteries. This leads to excessive dendrite growth that pierces the separator, causing battery failure and significantly reducing the battery's service life. Therefore, reducing the occurrence of dendrites and side reactions is crucial for the large-scale application of zinc-ion batteries.

[0003] There are many improvement schemes for these side reactions, such as plating Sn on the Zn surface to form an alloy, or forming an alloy with Cu, Bi, and Al, which provides more nucleation sites while reducing dendrite growth and greatly extending the battery life. Constructing an artificial solid electrolyte interface layer (ASEI) on Zn is also a way to regulate Zn 2+ Important approaches to electroplating chemistry include constructing an inorganic salt SEI film NaZnPO4, CaSO4·2H2O, NaTi2(PO4)3, TiO2, BaTiO3 and an organic SEI layer polyacrylonitrile, ZIF-8, covalent organic framework, etc. on the surface of the Zn electrode to inhibit the growth of Zn dendrites and thus extend the battery life. Alternatively, membrane modification can be used, such as fixing copper nanowires on a glass fiber membrane by filtration, which is beneficial for Zn 2+ The uniform distribution of flux, at the same time, the nanoscale size makes the Cu nanowires have a large specific surface area, which is beneficial to reduce the local current density and make the Zn 2+ The concentration field is homogenized, thereby inhibiting the growth of zinc dendrites. As a convenient and quick method, electrolyte additives are also widely studied, such as inorganic salt additives NH4F, LiCl, Sc 3+ and PbO etc. act as shields by adsorbing cations onto the surface of Zn sheets, thus inhibiting dendrite growth. Organic electrolyte additives such as 6-bromo-1H-benzimidazole, histidine, trimethyl phosphate and dodecyltrimethylammonium chloride etc., these organic additives can regulate Zn 2+ The solvation structure reduces the number of water molecules in the solvation sheath, thereby inhibiting by-products and reducing hydrogen evolution to extend battery life. Some of these additives are heavy metal salts, which will have a certain impact on the environment, and some organic additives will cause certain harm to the human body.

[0004] Interface modification is also an effective method to inhibit side reactions and reduce dendrite growth. For example, a dense layer of NaZnPO4 is deposited on the zinc surface to isolate it from direct contact with the electrolyte and effectively reduce the occurrence of side reactions. However, most of the current interface reactions are relatively cumbersome and complicated. Therefore, a simple and inexpensive zinc electrode coating preparation process is an important condition for its application. Summary of the Invention

[0005] The main purpose of the present invention is to provide a negative electrode material for aqueous zinc ion batteries, thereby reducing hydrogen evolution, Zn sheet corrosion and the generation of by-products, and overcoming the shortcomings of the existing technology.

[0006] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0007] S1: Weigh zinc salt and 2-methylimidazole separately, mix them in deionized water, stir at room temperature, centrifuge, wash, and dry to obtain ZIF-8 powder.

[0008] S2: The dried precursor powder and copper salt are stirred at a mass ratio of 14:1 at 40-90 °C for 6-24 h, and CNO powder is obtained by centrifugation, washing, and drying.

[0009] S3: The obtained CNO powder and polyvinylidene fluoride (PVDF) were mixed in a certain proportion using N-methylpyrrolidone (NMP) as solvent. The mixture was thoroughly ground in a mortar and then coated on the Zn foil surface with a thickness of 5-20 μm. The mixture was dried at 40-80°C for 6-24 hours to obtain the CNO@Zn anode.

[0010] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0011] (1) The raw material cost used in the present invention is low, and the co-precipitation and coating methods are simple to operate.

[0012] (2) The Cu2NO3(OH)3 negative electrode of the present invention provides abundant zinc-philic sites by introducing insoluble hydrophobic basic copper carbonate into the surface of the zinc electrode, so that Zn 2+ Uniform deposition reduces the formation of zinc dendrites, making the assembled symmetrical battery pure zinc electrode assembled symmetrical battery (cycle life 60 h) have excellent cycle stability and can have a cycle life of 1600 h.

[0013] (3) The Cu2NO3(OH)3 negative electrode of the present invention reduces the direct contact between the electrolyte and the zinc sheet due to its strong hydrophobicity, effectively reducing hydrogen evolution, corrosion and the formation of Zn4(OH)6SO4·xH2O by-products. As a result, the full-battery aqueous Al-MnO2 button cell assembled with Al-MnO2 has a capacity retention rate of 88.5% compared to bare zinc, and can be stably cycled for more than 400 cycles. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is the X-ray diffraction pattern of the Cu2NO3(OH)3 powder prepared in Example 1.

[0015] Figure 2 This is a scanning electron microscope image of Cu2NO3(OH)3@Zn prepared in Example 1.

[0016] Figure 3 This is the contact angle diagram of Cu2NO3(OH)3@Zn prepared in Example 1 and bare Zn in 2 mol / L ZnSO4 electrolyte after 4 minutes.

[0017] Figure 4 When the Cu2NO3(OH)3@Zn prepared in Example 1 is used as the negative electrode of the aqueous zinc ion battery, the current density is 1 mA / cm 2 , with an areal capacity of 0.5 mAh / cm 2 Below is the charge and discharge performance curve of a symmetrical battery.

[0018] Figure 5 When the Cu2NO3(OH)3@Zn prepared in Example 1 is used as the negative electrode of the aqueous zinc ion battery, the current density is 5 mA / cm 2 , with an areal capacity of 1 mAh / cm 2 Below is the charge and discharge performance curve of a symmetrical battery.

[0019] Figure 6 The half-cell prepared in Example 1 with Cu2NO3(OH)3@Zn as the negative electrode material and Cu foil as the positive electrode material was assembled at a current density of 2 mA / cm 2 , with an areal capacity of 0.5 mAh / cm 2 Coulomb efficiency diagram below.

[0020] Figure 7 The charge and discharge performance curve of a full battery assembled with Cu2NO3(OH)3@Zn prepared in Example 1 as the negative electrode material and Al-MnO2 as the positive electrode at a current density of 0.5 A / g.

[0021] Figure 8 The charge and discharge performance curve of a full battery assembled with Cu2NO3(OH)3@Zn prepared in Example 1 as the negative electrode material and Al-MnO2 as the positive electrode at a current density of 1 A / g. DETAILED DESCRIPTION

[0022] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0023] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0024] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The present description and examples are intended to be illustrative only.

[0025] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0026] Example 1

[0027] The preparation process of the basic copper nitrate coating for inhibiting zinc dendrite growth of the present invention comprises the following steps:

[0028] (1) Zinc nitrate hexahydrate and 2-methylimidazole in a molar ratio of 12:96 were weighed and dissolved in deionized water and stirred at room temperature for 4 h. The precursor ZIF-8 powder was obtained by centrifugation, washing, and drying.

[0029] (2) The dried precursor (M ZIF-8 :229.6 mol g -1 ) precursor powder and copper salt were stirred at a molar ratio of 1:2 at 60 °C for 12 h, and CNO powder was obtained by centrifugation, washing, and drying.

[0030] (3) The obtained CNO powder was mixed with polyvinylidene fluoride (PVDF) in a mass ratio of 9:1 using N-methylpyrrolidone (NMP) as solvent in a mortar, fully ground, and then coated on the surface of Zn foil with a thickness of 5 μm. The mixture was dried at 60 °C for 12 h to obtain the Cu2NO3(OH)3@Zn negative electrode.

[0031] The Cu2NO3(OH)3@Zn prepared in this example is denoted as CNO@Zn and used as the positive and negative electrodes of a button battery. A glass fiber separator and 2 mol / L ZnSO4 are used as the electrolyte. The button battery is assembled under conventional conditions and is denoted as a CNO@Zn / / CNO@Zn symmetrical battery.

[0032] The Cu2NO3(OH)3@Zn prepared in this example is denoted as CNO@Zn and used as the negative electrode of a button battery. Copper foil is used as the positive electrode. A glass fiber separator is used. 2 mol / L ZnSO4 is used as the electrolyte. The button battery is assembled under conventional conditions and denoted as CNO@Zn / / Cu half-cell.

[0033] The Cu2NO3(OH)3@Zn prepared in this example is denoted as CNO@Zn and used as the negative electrode of the button battery. Al-MnO2 is used as the positive electrode. A glass fiber separator is used, and 2 mol / L ZnSO4 and 0.2 mol / L MnSO4 are used as the electrolyte. The button battery is assembled under conventional conditions and is denoted as CNO@Zn / / Al-MnO2 full battery.

[0034] Comparative Example 1

[0035] Zinc foil is used as the positive and negative electrodes of the button battery, a glass fiber separator is used, and 2 mol / L ZnSO4 is used as the electrolyte. The button battery is assembled under conventional conditions and is recorded as a Zn / / Zn symmetric battery.

[0036] Zinc foil is used as the negative electrode of the button battery, copper foil is used as the positive electrode, a glass fiber separator is used, and 2 mol / L ZnSO4 is used as the electrolyte. The button battery is assembled under conventional conditions and is recorded as a Zn / / Cu half-cell.

[0037] Zinc foil is used as the negative electrode of the button battery, Al-MnO2 is used as the positive electrode, a glass fiber separator is used, 2 mol / L ZnSO4 and 0.2 mol / L MnSO4 are used as the electrolyte, and the button battery is assembled under conventional conditions, which is recorded as Zn / / Al-MnO2 full battery.

[0038] The obtained basic copper nitrate coating was subjected to X-ray diffraction analysis, scanning electron microscopy analysis, contact angle test, symmetrical battery cycle life test, half-cell coulomb efficiency test, full battery life and retention rate test, and the results are as follows: Figures 1-8 shown.

[0039] Figure 1 The figure shows the X-ray diffraction of the Cu2NO3(OH)3@Zn sample prepared in Example 1. From the figure, it can be seen that the diffraction peaks of basic copper nitrate can be well observed, indicating that the basic copper nitrate sample was successfully prepared. Figure 2 This is a scanning electron microscope image of the sample. In the image, it can be seen that basic copper nitrate nanosheets with an average particle size of 0.5-1 micron are evenly distributed on the surface of the zinc foil. Figure 3 Contact angle test of Cu2NO3(OH)3@Zn sample after 4 minutes in 2 mol / L ZnSO4 electrolyte.

[0040] Figure 4 and Figure 5 The symmetrical battery constant current charge and discharge test diagrams of the symmetrical battery assembled in Example 1 and Comparative Example 1 at low current and high current density are shown respectively. Figure 4 It can be seen that the symmetrical battery has a current density of 1 mA / cm 2 , with an areal capacity of 0.5 mAh / cm 2 Under the conditions of 100 nm CMOS and 0.8 V CMOS, the overpotential of CNO@Zn is significantly lower than that of the symmetrical battery with pure Zn electrode, indicating that the presence of the basic copper nitrate coating reduces the nucleation barrier of Zn and also reduces the polarization, promoting a relatively uniform zinc deposition / dissolution process, so that the symmetrical battery with basic copper nitrate coating has a cycle life of 1600 h compared to the 60 h cycle life of the pure zinc symmetrical battery. Figure 5 5 mA / cm 2 The high current density of 1 mAh / cm 2 This rule also applies to surface capacity, and the battery has a longer cycle life than the pure Zn electrode, indicating that the presence of basic copper nitrate can effectively reduce the occurrence of side reactions and thus extend battery life.

[0041] Figure 6 The half-cell assembled with Example 1 and Comparative Example 1 as the negative electrode of the button battery and Cu foil as the positive electrode of the button battery was tested at 2 mA / cm 2 Coulombic efficiency measured at 200 current densities. The figure shows that the coulombic efficiency of the pure Zn electrode fluctuates significantly after 190 cycles due to a series of side reactions, leading to battery damage. However, the half-cell coated with basic copper carbonate prepared in Example 1 maintains a coulombic efficiency of 99.8% after 1600 cycles, significantly exceeding that of Comparative Example 1, thanks to the excellent side reaction suppression capability of basic copper carbonate.

[0042] Figure 7 and Figure 8 These are the charge and discharge test diagrams of a full battery assembled with Example 1 and Comparative Example 1 as the negative electrode sheets of the button battery and Al-MnO2 as the positive electrode sheet of the button battery at different current densities. Figure 7 This is a charge and discharge test diagram at a current density of 0.5 A / g. From the figure, it can be seen that the initial capacity of the Zn / / Al-MnO2 battery is the same as the initial capacity of the CNO@Zn / / Al-MnO2. However, the capacity of the pure Zn electrode rapidly decays after 140 cycles due to various side reactions. However, the CNO@Zn / / Al-MnO2 full battery of Example 1 still has a capacity retention rate of 88.5% after 400 cycles due to the reduction of side reactions. Figure 8This is a charge and discharge test diagram at a current density of 1 A / g. From the figure, it can be seen that the Zn / / Al-MnO2 battery rapidly decays in capacity and finally fails after 900 cycles due to a series of side reactions. However, the CNO@Zn / / Al-MnO2 battery prepared in Example 1 can stably cycle 1400 cycles and maintain a retention rate of 93.4% because the side reactions are suppressed, which is significantly better than Comparative Example 1.

[0043] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for a person skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to replace some of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions claimed to be protected by the present invention.

Claims

1. A method for preparing a basic copper nitrate coating for inhibiting zinc dendrite growth, characterized in that: The steps include: S1: Zinc salt and 2-methylimidazole are mixed and stirred at room temperature, and the reaction product is centrifuged, washed, and dried to obtain ZIF-8 precursor powder; S2: ZIF-8 precursor powder and copper salt are stirred in a certain ratio at a certain temperature for a certain time, and then centrifuged, washed, and dried to obtain CNO powder; S3: The obtained CNO powder and polyvinylidene fluoride are fully ground in a solvent, and then coated on the surface of Zn foil. After drying, a basic copper nitrate coating Cu2NO3(OH)3@Zn is obtained to inhibit the growth of zinc dendrites.

2. The method for preparing a basic copper nitrate coating for inhibiting zinc dendrite growth according to claim 1, wherein: The zinc salt is any one of zinc oxide, zinc sulfate heptahydrate, zinc nitrate hexahydrate and zinc chloride.

3. The method for preparing a basic copper nitrate coating for inhibiting zinc dendrite growth according to claim 1, wherein: The copper salt described in S2 is one of copper acetate, copper nitrate, copper sulfate and copper chloride.

4. The method for preparing a basic copper nitrate coating for inhibiting zinc dendrite growth according to claim 1, wherein: The temperature in S2 is 40-90°C and the stirring time is 6-24 h.

5. The method for preparing a basic copper nitrate coating for inhibiting zinc dendrite growth according to claim 1, wherein: The coating thickness in S3 is 5-20 μm.

6. A basic copper nitrate coating for inhibiting zinc dendrite growth, characterized in that: The Cu2NO3(OH)3@Zn prepared by the method according to any one of claims 1 to 5 has XRD peaks at characteristic peak positions at approximately 12.8°, 21.58°, 25.77°, and 33.51° 2θ.

7. A negative electrode or positive electrode material, characterized in that The negative electrode or positive electrode material includes the basic copper nitrate coating for inhibiting zinc dendrite growth according to claim 6.

8. A symmetrical battery, characterized in that: The positive electrode sheet and / or the negative electrode sheet of the symmetrical battery adopts the basic copper nitrate coating for inhibiting zinc dendrite growth as claimed in claim 6.

9. A half-cell, characterized in that: The negative electrode of the half-cell adopts the basic copper nitrate coating for inhibiting zinc dendrite growth as claimed in claim 6.

10. A full battery, characterized in that: The negative electrode of the full battery adopts the basic copper nitrate coating for inhibiting zinc dendrite growth as claimed in claim 6.

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