Aqueous zinc-based battery negative electrode based on metal organic framework material and preparation method of aqueous zinc-based battery negative electrode

Abstract

The invention provides an aqueous zinc-based battery negative electrode based on a metal organic framework material and a preparation method of the aqueous zinc-based battery negative electrode, and belongs to the technical field of aqueous zinc-based batteries. The zinc oxide / imidazole organic ligand composite material is prepared from the following raw materials in parts by weight: 70 to 80 parts of zinc oxide, 20 to 30 parts of imidazole organic ligand, 5 to 20 parts of inorganic salt doped with metal ions, 10 to 20 parts of current collector and methanol, the imidazole organic ligand and the inorganic salt doped with metal ions are subjected to an in-situ coordination reaction to generate a metal organic framework interface layer, the surface of zinc oxide is coated with the metal organic framework interface layer to obtain a composite material, and the current collector serving as a supporting carrier and the composite material jointly form the negative electrode material. The metal organic framework interface layer is generated on the surface of the zinc oxide negative electrode in situ, and metal ions are doped, so that dendrite growth, hydrogen evolution and corrosion phenomena of the zinc negative electrode are effectively inhibited, the cycle life, the capacity retention rate and the discharge depth of the aqueous zinc-based battery are remarkably prolonged, and the negative electrode performance with high stability and high utilization rate is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of aqueous zinc-based batteries, and in particular to an aqueous zinc-based battery negative electrode based on a metal organic framework material and a preparation method thereof. Background Art

[0002] Among many aqueous batteries, aqueous zinc-ion batteries have become an ideal choice that has attracted much attention in the field of large-scale energy storage because of the outstanding advantages of the zinc negative electrode, such as good compatibility with aqueous electrolytes, lower reduction potential than other compatible metals, good processing performance and abundant reserves. It consists of a negative electrode, a positive electrode, an electrolyte and a separator, and is divided into alkaline zinc batteries and neutral or weakly acidic zinc-ion batteries.

[0003] For alkaline zinc batteries, the electrolyte is a KOH alkaline solution containing a small amount of zinc salt, and the positive electrode material is mostly transition metal oxides. During operation, the negative electrode zinc dissolves and deposits to produce Zn(OH)4 2- It will promote the formation of inactive Zn(OH)2 and ZnO, leading to passivation of the zinc negative electrode surface, affecting stability and zinc utilization; although the side reactions of neutral or weakly acidic zinc ion batteries are relatively mild, the zinc metal negative electrode still faces problems such as dendrites, hydrogen evolution, corrosion and passivation.

[0004] Due to the uneven surface morphology and composition of the electrode, the zinc negative electrode will have uneven zinc deposition, which will cause dendrite growth. In severe cases, it will pierce the diaphragm and cause the battery to short-circuit and fail. In the early stage of zinc deposition, Zn 2+ The Zn is preferentially deposited towards the high surface energy position to form a rough morphology, and the tip is protruding and electron-rich to attract more Zn. 2+ Inducing dendrites, and the thermodynamic properties of zinc make it more inclined to two-dimensional sheet deposition; H in the electrolyte + The electrons on the electrode surface become hydrogen atoms, which release hydrogen through Volmer-Heyrovsky or Volmer-Tafel reaction, consuming energy and electrolyte, causing the battery to swell, and the generated OH - Increasing the local pH value promotes zinc corrosion passivation. Hydrogen adhesion to the electrode will also hinder contact and uniform ion distribution, promote dendrite growth and increase the possibility of "dead zinc". In neutral or weakly acidic electrolytes, corrosion microbatteries are easily formed on the zinc surface. Dissolved oxygen, electrode defects and impurities will trigger corrosion reactions, leading to self-discharge and affecting the shelf stability of the battery.

[0005] Although metallic zinc is the preferred anode due to its high energy density and low cost, the above-mentioned issues have hindered its widespread application. While currently proposed embedded anodes can avoid some of these issues, they suffer from high electrode potential and low theoretical capacity. Summary of the Invention

[0006] In order to overcome the shortcomings of the existing technology, the purpose of the present invention is to provide an aqueous zinc-based battery negative electrode based on metal-organic framework materials and a preparation method thereof. By in situ generating a metal-organic framework interface layer on the surface of the zinc oxide negative electrode and doping it with metal ions, the dendrite growth, hydrogen evolution and corrosion of the zinc negative electrode are effectively inhibited, and the cycle life, capacity retention rate and discharge depth of the aqueous zinc-based battery are significantly improved, thereby achieving high stability and high utilization rate of the negative electrode performance.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] A metal-organic framework-based aqueous zinc-based battery negative electrode, the negative electrode comprising the following raw materials: 70-80 parts by weight of zinc oxide, 20-30 parts of an imidazole organic ligand, 5-20 parts of an inorganic salt doped with metal ions, 10-20 parts of a current collector, and methanol;

[0009] The imidazole organic ligand and the inorganic salt doped with metal ions form a metal organic framework interface layer through an in-situ coordination reaction, which is coated on the surface of zinc oxide to obtain a composite material. The current collector serves as a supporting carrier and together with the composite material constitutes a negative electrode material.

[0010] Preferably, the doping metal ion is one of indium, copper and bismuth.

[0011] Preferably, the imidazole organic ligand is dimethylimidazole or imidazole cation, the current collector is copper foil, and the metal organic framework is a ZIF-8 type framework.

[0012] Preferably, the inorganic salt containing doped metal ions is nitrate or chloride.

[0013] The present invention also provides a method for preparing the above-mentioned aqueous zinc-based battery negative electrode based on the metal organic framework material, comprising the following steps:

[0014] S1. Dissolve zinc oxide and an inorganic salt containing doped metal ions in methanol according to the raw material ratio to form a suspension A;

[0015] S2, dissolving an imidazole organic ligand in methanol, stirring to form a solution B, and adding the solution B to the suspension A and stirring to generate a metal-organic framework-coated zinc oxide composite material through a coordination reaction;

[0016] S3, filtering, washing and drying the metal organic framework-coated zinc oxide composite material;

[0017] S4. Mixing and grinding the treated composite material with the electrolyte material and the binder, then adding isopropyl alcohol and continuing grinding, then adding polytetrafluoroethylene emulsion, and evenly applying it on the current collector, and obtaining the negative electrode material after drying.

[0018] Preferably, in step S1, the zinc oxide accounts for 60-70% of the total mass of the battery pole piece, and the inorganic salt containing doped metal ions accounts for 5-20% of the total mass of the electrode pole piece.

[0019] Preferably, in step S2, the imidazole organic ligand accounts for 20-30% of the total mass of the electrode plate, the solution B is stirred for 10-30 minutes, and the solution B and suspension A are mixed and stirred for 4-6 hours.

[0020] Preferably, in step S3, the washing process of the metal organic framework-coated zinc oxide composite material is: washing with deionized water and methanol for 3 times; the drying process is: drying in an oven at 60-100° C. for 2-4 hours.

[0021] Preferably, in step S4, the specific process of the negative electrode material is: mixing the treated composite material with zinc powder, polyvinyl alcohol, sodium dodecylbenzenesulfonate, potassium polymethacrylate, bismuth trioxide, aluminum oxide, and indium hydroxide and grinding them for 30-40 minutes, adding isopropyl alcohol and continuing to grind for 20-30 minutes, then adding 5%-15% mass fraction of polytetrafluoroethylene emulsion, evenly applying it on the copper foil current collector, and drying to obtain the negative electrode material.

[0022] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0023] (1) The present invention generates a dense and uniform metal-organic framework interface layer in situ on the surface of the zinc oxide negative electrode and introduces doped metal ions such as indium and copper to construct an interface structure with ion screening and uniform conduction functions, thereby regulating the zinc ion deposition behavior, inhibiting dendrite growth and hydrogen evolution side reactions, and significantly improving the cycle stability of aqueous zinc-based batteries, so that the negative electrode maintains structural integrity during long-term cycles, reduces active material loss, and extends battery life.

[0024] (2) The present invention optimizes the charge distribution and ion transport path on the electrode surface through the synergistic effect of the metal-organic framework interface layer and zinc oxide, reduces reaction polarization, improves the reversibility of the electrode reaction, and achieves high capacity retention of the battery under deep discharge conditions and stable operation under high current density. At the same time, it enhances the corrosion resistance of the negative electrode to the electrolyte, improves the utilization rate of zinc metal, and ensures that the battery can perform efficiently under different working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. 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 any creative work.

[0026] Figure 1 This is a flow chart of a method for preparing an aqueous zinc-based battery negative electrode based on a metal organic framework material according to the present invention;

[0027] Figure 2 This is a SEM image of a metal organic framework-based aqueous zinc-based battery negative electrode material provided by the present invention; wherein, Figure 2 (a) is the SEM image of Example 1, Figure 2 (b) is the SEM image of Example 2, Figure 2 (c) is the SEM image of Comparative Example 1, Figure 2 (d) is the SEM image of Comparative Example 2;

[0028] Figure 3 XPS graph of an aqueous zinc-based battery negative electrode based on a metal-organic framework material according to the present invention;

[0029] Figure 4 This is a charge and discharge curve diagram of the battery provided by the present invention. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0031] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] like Figure 1 As shown, the present invention provides a method for preparing an aqueous zinc-based battery negative electrode based on a metal organic framework material, comprising the following steps:

[0033] S1. Dissolve zinc oxide and an inorganic salt doped with metal ions in methanol according to the raw material ratio to form a suspension A; wherein the zinc oxide accounts for 60-70% of the total mass of the battery electrode, and the inorganic salt doped with metal ions accounts for 5-20% of the total mass of the electrode.

[0034] S2. Dissolve the imidazole organic ligand in methanol and stir for 10-30 minutes to form solution B, and add the solution B to the suspension A and stir for 4-6 hours to generate a metal-organic framework-coated zinc oxide composite material through coordination reaction; the imidazole organic ligand accounts for 20-30% of the total mass of the electrode plate.

[0035] S3, filtering the metal organic framework-coated zinc oxide composite material, washing it with deionized water and methanol three times, and drying it in an oven at 60-100° C. for 2-4 hours;

[0036] S4. Mixing and grinding the treated composite material with the electrolyte material and the binder, then adding isopropyl alcohol and continuing grinding, then adding polytetrafluoroethylene emulsion, and evenly applying it on the current collector, and obtaining the negative electrode material after drying.

[0037] Specifically, the specific process of the negative electrode material is as follows: the treated composite material is mixed with zinc powder, polyvinyl alcohol, sodium dodecylbenzene sulfonate, potassium polymethacrylate, bismuth trioxide, aluminum oxide, and indium hydroxide and ground for 30-40 minutes, isopropyl alcohol is added and ground for 20-30 minutes, 5%-15% by mass of polytetrafluoroethylene emulsion is added, and the mixture is evenly applied to the copper foil current collector, and dried to obtain the negative electrode material.

[0038] In addition, in the above step S1, the negative electrode material is composed of the following raw materials: by weight, 70-80 parts of zinc oxide, 20-30 parts of imidazole organic ligand, 5-20 parts of inorganic salt containing doped metal ions, 10-20 parts of current collector and methanol; the doped metal ion is one of indium, copper, and bismuth, and the inorganic salt containing doped metal ions is nitrate or chloride.

[0039] The imidazole organic ligand and the inorganic salt doped with metal ions undergo an in-situ coordination reaction to form a metal-organic framework interface layer, which is then coated on the surface of zinc oxide to form a composite material. The current collector serves as a support carrier and together with the composite material, forms the negative electrode material. The imidazole organic ligand is dimethylimidazole or an imidazolium cation, the current collector is copper foil, and the metal-organic framework is a ZIF-8 framework.

[0040] Example 1

[0041] In this embodiment, the negative electrode raw material formula prepared is: 80 parts of zinc oxide, 30 parts of dimethylimidazole, 20 parts of current collector, 15 parts of inorganic salt containing indium ions, and 15 parts of inorganic salt containing copper ions.

[0042] The preparation process is as follows: First, 7g of zinc oxide (the total mass of the battery electrode) and 2g of indium nitrate are dissolved in 75ml of methanol to form Suspension A. 2.5g of dimethylimidazole is then dissolved in 75ml of methanol. The methanol solution containing dimethylimidazole is then stirred for 10 minutes, mixed with Suspension A, and stirred for another 4 hours. Finally, the mixture is filtered and washed three times with deionized water and methanol to obtain the final product, ZIF-8, which is then dried in an oven at 100°C for 2 hours.

[0043] Next, 7.116g of the prepared negative electrode material was mixed with the electrolyte material and binder, specifically 1.38g of zinc powder, 0.09g of polyvinyl alcohol, 0.006g of sodium dodecylbenzenesulfonate, 0.003g of potassium polymethacrylate, 0.456g of bismuth trioxide, 0.096g of aluminum oxide, and 0.012g of indium hydroxide. After grinding for 30 minutes, 7.5ml of isopropyl alcohol was added and grinding continued for another 30 minutes. After sufficient grinding, 0.48g of polytetrafluoroethylene emulsion was added and, after solidification, evenly applied to the copper foil. A commercial nickel positive electrode was used as the positive electrode. The battery was assembled in an air atmosphere. The separator was made of plastic, and the electrolyte was a zinc oxide-saturated potassium hydroxide solution.

[0044] Example 2

[0045] The difference from Example 1 is that the added indium nitrate is replaced by copper chloride of equal mass, and the rest is the same.

[0046] Comparative Example 1

[0047] The difference from Example 1 is that indium nitrate is not added, and the intermediate process is the same as that of Example 1.

[0048] Comparative Example 2

[0049] The difference from Example 1 is that indium nitrate and dimethylimidazole are not added, and the intermediate process is the same as that of Example 1.

[0050] After fully soaking the assembled battery electrodes of Examples 1-2 and Comparative Examples 1-2 in the electrolyte, they are placed in a mold, and the electrochemical performance of the battery is evaluated and analyzed at a certain current density. The cycle life, coulombic efficiency, overpotential and other performance can be obtained through cycle testing.

[0051] Therefore, the test results were shown in Table 1 by using the Xinwei battery testing system and compared with the discharge capacity test results of the battery with the homemade zinc oxide negative electrode.

[0052] Table 1 Discharge capacity test data

[0053]

[0054]

[0055] As shown in Table 1, the ZIF-8 structure, formed by combining zinc oxide with dimethylimidazole, effectively improves battery capacity retention compared to batteries with homemade zinc oxide anodes, maintaining a higher capacity retention than the homemade comparison sample for the same number of cycles. Batteries fabricated with copper ions doped in ZIF-8 showed no significant difference in capacity retention over the first 20 cycles. After 20 cycles, the capacity retention decreased significantly compared to the ZIF-8 battery, but remained superior to that of the homemade battery. Batteries fabricated with indium ions doped in ZIF-8 showed significantly better capacity retention than the ZIF-8 battery for the same number of cycles, maintaining a stable capacity retention of over 80% for 150 cycles and exceeding 90% in most cases. Therefore, batteries fabricated with indium ion-doped ZIF-8 exhibit significant capacity retention advantages.

[0056] Reference Figure 2 The magnification of (a), (b), (c) and (d) is 10000 times. Figure 2 It can be seen that Comparative Example 2 has obvious dendrite growth, while Comparative Example 1 forms a more uniform modified layer on the zinc negative electrode surface after adding dimethylimidazole. The negative electrode surface modified layer of Example 2 is looser than that of Comparative Example 2, while the negative electrode surface modified layer of Example 1 is smoother and denser, and has the best effect in inhibiting dendrite growth.

[0057] To further confirm the formation of the negative electrode surface modification layer, XPS energy spectrum analysis was performed on the modified zinc negative electrode. Figure 3 The XPS images of aqueous zinc-based battery anode materials based on metal organic frameworks are provided. Figure 3 The formation of its surface modification layer was confirmed.

[0058] Table 2 XPS analysis data

[0059]

[0060]

[0061] in addition, Figure 4 The changes in voltage and capacity of the comparative sample and the indium ion-doped ZIF-8 sample during the discharge process are shown. Figure 4 It was confirmed that under the same discharge environment, the voltage of the battery containing the indium ion-doped ZIF-8 structure dropped more slowly during the discharge process, indicating that its discharge performance was better than that of the comparative sample, with a deeper discharge depth and higher discharge capacity.

[0062] Based on the above results, Example 1 has the best overall performance in terms of capacity retention, discharge depth, and negative electrode utilization, meeting industry standards. Although Cu ion-doped ZIF-8 homemade pole piece battery can improve battery performance, the copper ion doping has the effect of promoting hydrogen evolution under alkaline conditions, so its capacity retention effect is slightly worse than that of the non-ion-doped ZIF-8 homemade pole piece battery. Therefore, the indium-doped ZIF-8 structure can significantly improve battery performance.

[0063] Therefore, the above-mentioned aqueous zinc-based battery negative electrode based on metal-organic framework materials and its preparation method are adopted. By in situ generating a metal-organic framework interface layer on the surface of the zinc oxide negative electrode and doping metal ions, the dendrite growth, hydrogen evolution and corrosion of the zinc negative electrode are effectively inhibited, and the cycle life, capacity retention rate and discharge depth of the aqueous zinc-based battery are significantly improved, thereby achieving high stability and high utilization rate of the negative electrode performance.

[0064] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0065] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A negative electrode for an aqueous zinc-based battery based on a metal-organic framework material, characterized in that: The negative electrode is composed of the following raw materials: by weight, 70-80 parts of zinc oxide, 20-30 parts of imidazole organic ligand, 5-20 parts of inorganic salt containing doped metal ions, 10-20 parts of current collector and methanol; The imidazole organic ligand and the inorganic salt doped with metal ions form a metal organic framework interface layer through an in-situ coordination reaction, which is coated on the surface of zinc oxide to obtain a composite material. The current collector serves as a supporting carrier and together with the composite material constitutes a negative electrode material.

2. The aqueous zinc-based battery negative electrode based on metal organic framework material according to claim 1, characterized in that: The doped metal ion is one of indium, copper and bismuth.

3. The aqueous zinc-based battery negative electrode based on metal organic framework material according to claim 1, characterized in that: The imidazole organic ligand is dimethylimidazole or imidazole cation, the current collector is copper foil, and the metal organic framework is a ZIF-8 type framework.

4. The aqueous zinc-based battery negative electrode based on metal organic framework material according to claim 1, characterized in that: The inorganic salt containing doped metal ions is nitrate or chloride.

5. A method for preparing an aqueous zinc-based battery negative electrode based on a metal organic framework material according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Dissolve zinc oxide and an inorganic salt containing doped metal ions in methanol according to the raw material ratio to form a suspension A; S2, dissolving an imidazole organic ligand in methanol, stirring to form a solution B, and adding the solution B to the suspension A and stirring to generate a metal-organic framework-coated zinc oxide composite material through a coordination reaction; S3, filtering, washing and drying the metal organic framework-coated zinc oxide composite material; S4. Mixing and grinding the treated composite material with the electrolyte material and the binder, then adding isopropyl alcohol and continuing grinding, then adding polytetrafluoroethylene emulsion, and evenly applying it on the current collector, and obtaining the negative electrode material after drying.

6. The method for preparing an aqueous zinc-based battery negative electrode based on a metal organic framework material according to claim 5, characterized in that: In step S1, the zinc oxide accounts for 60-70% of the total mass of the battery pole piece, and the inorganic salt containing doped metal ions accounts for 5-20% of the total mass of the electrode pole piece.

7. The method for preparing an aqueous zinc-based battery negative electrode based on a metal organic framework material according to claim 5, characterized in that: In step S2, the imidazole organic ligand accounts for 20-30% of the total mass of the electrode plate, the solution B is stirred for 10-30 minutes, and the solution B and suspension A are mixed and stirred for 4-6 hours.

8. The method for preparing an aqueous zinc-based battery negative electrode based on a metal organic framework material according to claim 5, characterized in that: In step S3, the metal organic framework-coated zinc oxide composite material is washed by using deionized water and methanol for three times; and the drying process is dried in an oven at 60-100° C. for 2-4 hours.

9. The method for preparing an aqueous zinc-based battery negative electrode based on a metal organic framework material according to claim 5, characterized in that: In step S4, the specific process of the negative electrode material is as follows: the treated composite material is mixed with zinc powder, polyvinyl alcohol, sodium dodecylbenzene sulfonate, potassium polymethacrylate, bismuth trioxide, aluminum oxide, and indium hydroxide and ground for 30-40 minutes, isopropyl alcohol is added and ground for 20-30 minutes, and then 5%-15% mass fraction of polytetrafluoroethylene emulsion is added, and the mixture is evenly applied to the copper foil current collector, and dried to obtain the negative electrode material.

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