Preparation method and application of zinc negative electrode with nano-scale ultra-thin protective layer

Abstract

The present invention provides a method for preparing and applying a zinc negative electrode with a nanoscale ultra-thin protective layer, belonging to the field of energy material technology. The method is intended to prevent the occurrence of hydrogen evolution reaction and the generation of byproducts on the zinc surface, thereby avoiding corrosion and dendrite problems that affect the electrochemical performance of zinc-based batteries. The main solution is to deposit a nanoscale TiN protective layer on the surface of the metallic zinc negative electrode of an aqueous zinc ion battery using atomic layer vapor deposition technology as a zinc negative electrode protective layer. This ultra-thin protective layer not only prevents direct contact between the zinc negative electrode and the electrolyte, effectively inhibiting corrosion and electrochemical hydrogen evolution reaction on the zinc negative electrode surface, but also ensures that the electric field is evenly distributed on the zinc negative electrode surface, making zinc deposition more uniform. At the same time, the zinc-philic bond can effectively induce directional zinc deposition, successfully inhibiting zinc dendrites and significantly improving its structural and performance stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy materials, and in particular relates to a preparation method and application of a zinc negative electrode with a nano-scale ultra-thin protective layer. Background Art

[0002] The current energy storage sector continues to be dominated by lithium-ion batteries. However, growing concerns about low cost (lithium and cobalt), safety, environmental impact, and limited resource supply have prompted researchers to search for alternative energy storage devices. Aqueous batteries, owing to their use of aqueous electrolytes, have garnered particular attention due to their non-flammability and high ionic conductivity. Their inherent safety characteristics and good compatibility with the atmospheric environment can eliminate the need for complex battery management. Highly safe, high-performance energy storage systems are of great significance to the development of strategic emerging industries such as clean energy and smart grids. Aqueous zinc-based batteries, utilizing abundant, high-capacity metallic zinc as the anode, offer advantages such as high safety, high specific energy, and low cost. Due to their promising applications in large-scale energy storage, they have become a research hotspot. However, zinc anodes currently suffer from severe corrosion and dendrite formation problems, which compromise the electrochemical performance of zinc-based batteries. Zinc ions typically nucleate at localized, high-concentration interfacial regions. The low surface energy of zinc nuclei in these regions induces uneven zinc ion deposition, leading to dendrite growth and capacity degradation, and even short circuits. Therefore, enhancing interfacial stability is a key and challenging issue in improving the performance of zinc-based batteries. Summary of the Invention

[0003] The purpose of the present invention is to prevent the occurrence of hydrogen evolution reaction on the zinc surface and the generation of by-products, avoid corrosion and dendrite problems, and affect the electrochemical performance of zinc-based batteries.

[0004] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0005] A method for preparing a zinc negative electrode with a nanoscale ultra-thin protective layer comprises the following steps:

[0006] 1) placing a metal zinc negative electrode in a box-type muffle furnace for a certain period of time to obtain a zinc negative electrode with a zinc oxide film formed on the surface;

[0007] 2) transferring the zinc anode with a zinc oxide film formed on the surface to an atomic layer deposition device to deposit a protective layer under high temperature conditions to obtain a zinc anode with a nano-scale ultra-thin protective layer;

[0008] Specifically, in step 1), the heating temperature in the box-type muffle furnace is 100°C, the heating rate is 10°C / min, and the heating time is 5, 15, 30, 45, and 60 mins, respectively; the purpose of heating and calcining in the muffle furnace is to form an oxide film on the surface of the zinc negative electrode; during the atomic layer vapor deposition process, the surface oxide film can provide more active sites for deposition, facilitating the formation of a continuous thin film; the number of active sites is related to the heating time. If the heating time is too low, the TiN film will be discontinuous or even no film will be formed. If the heating time is too long, the oxide film will be too thick, which will cause the TiN film to be too thick, resulting in reduced performance.

[0009] Specifically, in step 2), the high temperature is 350° C., the titanium source is titanium tetraisopropoxide, and the nitrogen source is ammonia:

[0010] Specifically, in step 2), the number of deposition cycles is 300, 500, or 700;

[0011] Specifically, in step 2), the film thickness is 60, 100, or 140 nanometers;

[0012] In the present invention, the nanoscale ultra-thin protective layer not only avoids direct contact between the zinc negative electrode and the electrolyte, preventing the occurrence of hydrogen evolution reaction on the zinc surface and the generation of by-products, but also the nitrogen-containing bonds have stronger adsorption of zinc atoms, which can effectively induce the directional deposition of zinc ions and inhibit the growth of zinc dendrites. In addition, the uniform ultra-thin protective layer has good conductivity while having low interfacial impedance, realizing faster kinetic transmission, making the zinc deposition more uniform, and having good stability at the electrode-electrolyte interface, thereby greatly improving the cycle life of the zinc-based battery.

[0013] The technical solution of the present invention proposes an aqueous secondary battery, including a positive electrode sheet, a zinc negative electrode sheet made of the zinc negative electrode material as described above, a diaphragm and an electrolyte, wherein the zinc negative electrode sheet and the positive electrode sheet are respectively located on both sides of the diaphragm, and the hydrophobic conductive polymer film on one surface of the zinc negative electrode sheet is adjacent to the diaphragm.

[0014] Furthermore, the diaphragm includes but is not limited to a glass fiber diaphragm, a PP diaphragm, a PE diaphragm and a filter paper diaphragm.

[0015] Furthermore, the solute of the electrolyte includes but is not limited to at least one of zinc sulfate, zinc trifluoromethanesulfonate, zinc perchlorate and zinc chloride; the solvent of the electrolyte is ultrapure water; the amount and concentration of the electrolyte are conventional injection amounts and concentrations in the art, generally 60-100 μL.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] (1) The zinc negative electrode with a nano-scale ultra-thin protective layer constructed in the present invention can regulate the electric field and / or ion field during the dissolution / deposition of zinc ions during the charge and discharge process, induce the directional deposition of zinc ions, and inhibit the formation of zinc dendrites, thereby realizing a high-stability, long-cycle-life aqueous zinc-based energy storage system.

[0018] (2) Compared with the existing protective layers that have been reported to inhibit zinc dendrite formation, the film thickness of this protective layer can be precisely controlled at the nanoscale. Nanoscale interface modification can achieve faster kinetic transport at lower interface impedance and produce high-energy-density metal anodes with extended cycling capabilities.

[0019] (3) The purpose of the present invention is to provide a metal zinc negative electrode with a protective layer on the surface, which constructs an ultra-thin protective layer with a nanometer scale on the surface of the zinc negative electrode, wherein atomic layer deposition is a unique technology with good coverage and conformal deposition. Due to its self-limiting nature, the thickness of the atomic layer deposited film can be precisely controlled at the nanometer scale. The protective layer not only avoids direct contact between the zinc negative electrode and the electrolyte, prevents the occurrence of hydrogen evolution reaction on the zinc surface and the generation of by-products, but also the titanium nitride protective coating can effectively inhibit the growth of zinc dendrites and side reactions; unexpectedly, the TiN film can regulate the crystal orientation of zinc deposition by inducing lateral growth, promotes the deposition of the (002) crystal plane parallel to the substrate, thereby inhibiting the vertical growth of zinc dendrites. In addition, the uniform ultra-thin protective layer has good conductivity while having low interface impedance, realizes faster kinetic transmission, reduces battery loss, and has good stability at the electrode-electrolyte interface, thereby greatly improving the cycle life of the zinc-based battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Attachment Figure 1 Schematic diagram of the internal structure of the battery;

[0021] Attachment Figure 2 The zinc negative electrode with a nano-scale ultra-thin protective layer provided in Example 1 of the present invention and the zinc negative electrode of Comparative Example 1 were tested at current densities of 1, 3, 5, and 8 mA cm -2 Polarization voltage-cycle time diagram tested under rate charge and discharge conditions;

[0022] Attachment Figure 3 X-ray photoelectron spectra of the zinc negative electrode with a nanoscale ultra-thin protective layer provided in Example 2 of the present invention and the zinc negative electrode of Comparative Example 2;

[0023] Attachment Figure 4 The zinc negative electrode with a nano-scale ultra-thin protective layer provided by Example 2 of the present invention and the zinc negative electrodes of Comparative Examples 2 and 3 were tested at current densities of 1, 3, 5, and 8 mA cm -2 Polarization voltage-cycle time diagram tested under rate charge and discharge conditions;

[0024] Attachment Figure 5 The zinc negative electrode with nano-thin protective layer provided by Example 2 of the present invention and the zinc negative electrode of Comparative Example 2 have a high conductivity at 5 mA cm -2 Polarization voltage-cycle time diagram of charge and discharge test at current density;

[0025] Attachment Figure 6 The zinc negative electrode with a nano-scale ultra-thin protective layer provided by Example 3 of the present invention and the zinc negative electrode of Comparative Example 4 were tested at current densities of 1, 3, 5, and 8 mA cm -2 Polarization voltage-cycle time diagram tested under rate charge and discharge conditions;

[0026] Reference numerals

[0027] 1-first zinc foil, 2-first protective layer, 3-diaphragm, 4-second protective layer, 5-second zinc foil. DETAILED DESCRIPTION

[0028] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0029] The following embodiments are only used to illustrate the present invention. The specific implementation of the present invention is not limited to these descriptions. Any deductions, modifications or substitutions made based on the concept of the present invention should be deemed to be within the scope of protection of the claims submitted by the present invention.

[0030] Since the improvements of this invention only relate to the zinc negative electrode of zinc-based batteries, the positive electrode, separator, and electrolyte described in the zinc secondary battery provided herein are all types of positive electrodes, separators, and aqueous electrolytes used in conventional zinc-based secondary batteries. In the examples, where specific conditions are not specified, conventional conditions or those recommended by the manufacturer were followed. Reagents or instruments used, where the manufacturer is not specified, are all commercially available conventional products.

[0031] Example 1

[0032] The method for preparing a zinc negative electrode having a nanoscale ultra-thin protective layer in this embodiment comprises the following steps:

[0033] 1) placing a metallic zinc negative electrode in a box-type muffle furnace, heating the metal zinc negative electrode to 100°C, heating at a rate of 10°C / min, and heating for 15 minutes to obtain a zinc negative electrode having a zinc oxide film formed on the surface;

[0034] 2) The zinc anode with a zinc oxide film formed on its surface was transferred to an atomic layer deposition apparatus and deposited for 500 cycles at 350°C with titanium tetraisopropoxide as the titanium source and ammonia as the nitrogen source to obtain a zinc anode with a nanoscale ultra-thin protective layer;

[0035] 3) Using 2 mol / L ZnSO4 aqueous solution as electrolyte and glass fiber separator, Zn||Zn symmetrical cells were assembled according to conventional battery assembly methods in the field. -2 Tested under the charge and discharge conditions of the rate, as shown in the attached Figure 2 shown.

[0036] Comparative Example 1

[0037] The untreated zinc sheet was used as electrolyte with 2 mol / L ZnSO4 aqueous solution and glass fiber separator to assemble Zn||Zn symmetrical cells according to the conventional battery assembly method in the field. The cells were tested at current densities of 1, 3, 5, and 8 mA cm -2 The test was conducted under rate charge and discharge conditions; the cycle overpotential of the Zn||Zn symmetric battery assembled with a zinc negative electrode with a nano-scale ultra-thin protective layer was lower than that of Comparative Example 1.

[0038] Example 2

[0039] The method for preparing a zinc negative electrode having a nanoscale ultra-thin protective layer in this embodiment comprises the following steps:

[0040] 1) placing a metallic zinc negative electrode in a box-type muffle furnace, heating the metal zinc negative electrode to 100°C, heating the metal zinc negative electrode at a rate of 10°C / min, and heating the metal zinc negative electrode for 30 minutes to obtain a zinc oxide film formed on the surface of the metal zinc negative electrode;

[0041] 2) The zinc anode with a zinc oxide film formed on its surface was transferred to an atomic layer deposition apparatus and deposited for 500 cycles at 350°C with titanium tetraisopropoxide as the titanium source and ammonia as the nitrogen source to obtain a zinc anode with a nanoscale ultra-thin protective layer;

[0042] 3) The zinc negative electrode with nano-thin protective layer obtained above was characterized by X-ray photoelectron spectroscopy (XPS), as shown in the attached Figure 3 As shown in the figure, compared with Comparative Example 2, the surface of the zinc negative electrode with a nano-thin protective layer has TiN and TiO2 signals; a 2 mol / L ZnSO4 aqueous solution is used as the electrolyte, a glass fiber separator is used, and a Zn||Zn symmetrical battery is assembled according to the conventional battery assembly method in the field. At current densities of 1, 3, 5, and 8 mA cm -2 Tested under the charge and discharge conditions of the rate, as shown in the attached Figure 4As shown, compared with Comparative Examples 2 and 3, the Zn||Zn symmetric battery assembled with a zinc negative electrode having a nano-scale ultra-thin protective layer has a lower cycle overpotential; -2 Long cycle test under current density conditions, as shown in the attached Figure 5 As shown, compared with Comparative Example 2, the Zn||Zn symmetric battery assembled with a zinc negative electrode having a nanoscale ultra-thin protective layer has a lower cycle overpotential and a longer cycle life. However, if the heating time is too short, the oxide film will have too few active sites, resulting in discontinuous or even no TiN film formation, leading to reduced performance; therefore, Example 2 has a lower overpotential than Example 1.

[0043] Comparative Example 2

[0044] The untreated zinc sheets were characterized by X-ray photoelectron spectroscopy (XPS). A 2 mol / L ZnSO4 aqueous solution was used as the electrolyte and a glass fiber separator was used to assemble Zn||Zn symmetrical cells according to conventional cell assembly methods in the art. The Zn||Zn symmetrical cells were assembled at current densities of 1, 3, 5, and 8 mA cm -2 Tested under the charge and discharge conditions of the rate, as shown in the attached Figure 4 shown.

[0045] Comparative Example 3

[0046] The zinc sheet was heated in a box-type muffle furnace at 100°C for 30 mins, and a 2 mol / L ZnSO4 aqueous solution was used as the electrolyte. A glass fiber separator was used to assemble a Zn||Zn symmetrical battery according to the conventional battery assembly method in the field. The Zn||Zn symmetrical battery was assembled at current densities of 1, 3, 5, and 8 mA cm -2 Tested under the charge and discharge conditions of the rate, as shown in the attached Figure 4 shown.

[0047] Example 3

[0048] The method for preparing a zinc negative electrode having a nanoscale ultra-thin protective layer in this embodiment comprises the following steps:

[0049] 1) placing a metallic zinc negative electrode in a box-type muffle furnace, heating the metal zinc negative electrode to 100°C, heating at a rate of 10°C / min, and heating for 45 minutes to obtain a zinc negative electrode having a zinc oxide film formed on the surface;

[0050] 2) The zinc anode with a zinc oxide film formed on its surface was transferred to an atomic layer deposition apparatus and deposited for 700 cycles at 350°C using titanium tetraisopropoxide as the titanium source and ammonia as the nitrogen source to obtain a zinc anode with a nanoscale ultra-thin protective layer;

[0051] 3) Using 2 mol / L ZnSO4 aqueous solution as electrolyte and glass fiber separator, Zn||Zn symmetrical cells were assembled according to conventional battery assembly methods in the field. -2 Tested under the charge and discharge conditions of the rate, as shown in the attached Figure 6 As shown, the Zn||Zn symmetrical battery assembled with a zinc negative electrode having a nanoscale ultra-thin protective layer has a lower cycle overpotential than Comparative Example 4. Excessive deposition cycles will cause the TiN film to become thicker, which is not conducive to the kinetic transport of ions, increases the battery impedance and loss during the cycle, and shortens the lifespan. Therefore, compared with Example 2, Example 3 has a higher overpotential.

[0052] Comparative Example 4

[0053] The untreated zinc sheet was used as electrolyte with 2 mol / L ZnSO4 aqueous solution and glass fiber separator to assemble Zn||Zn symmetrical cells according to the conventional battery assembly method in the field. The cells were tested at current densities of 1, 3, 5, and 8 mA cm -2 Tested under rate charge and discharge conditions;

[0054] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for preparing a zinc negative electrode having a nanoscale ultra-thin protective layer, characterized in that: The following steps are involved: Step 1) placing a metallic zinc negative electrode in a box-type muffle furnace to obtain a zinc negative electrode with a zinc oxide film formed on the surface; Step 2) transferring the zinc anode with a zinc oxide film formed on its surface to an atomic layer deposition apparatus to deposit a protective layer under high temperature conditions to obtain a zinc anode with a TiN nanoscale ultra-thin protective layer, wherein the titanium source selected in the atomic layer deposition apparatus is titanium tetraisopropoxide and the nitrogen source is ammonia; In step 2), the high temperature is 350° C., the titanium source is titanium tetraisopropoxide, and the nitrogen source is ammonia; In step 2), the number of deposition cycles is 300, 500 or 700; In step 2), the film thickness is 60, 100 or 140 nanometers.

2. The method for preparing a zinc negative electrode having a nanoscale ultra-thin protective layer according to claim 1, wherein: In step 1), the heating temperature in the box-type muffle furnace is 100° C., the heating rate is 10° C. / min, and the heating time is 5 to 60 minutes.

3. The method for preparing a zinc negative electrode having a nano-scale ultra-thin protective layer according to claim 2, wherein: The heating time is 30 minutes.

4. A zinc negative electrode having a nanoscale ultra-thin protective layer prepared according to the method according to any one of claims 1 to 3.

5. An aqueous secondary battery comprising a positive electrode, a separator, an electrolyte, and the zinc negative electrode according to claim 4, characterized in that: The zinc negative electrode sheet and the positive electrode sheet are respectively located on both sides of the diaphragm, and the protective layer on the surface of one side of the zinc negative electrode is adjacent to the diaphragm.

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