Zinc negative electrode interface self-protection method and system for aqueous zinc ion battery

Abstract

The invention discloses a zinc negative electrode interface self-protection method and system for an aqueous zinc ion battery, and belongs to the technical field of electrochemical energy storage. The protection method disclosed by the invention comprises the following steps: immersing a zinc negative electrode into an electrolyte containing citric acid, carrying out electrochemical pre-cycle treatment, and then forming a continuously covered zinc-loving-hydrophobic interface layer on the surface of the zinc negative electrode; the continuously covered zinc-loving-hydrophobic interface layer comprises a zinc-loving area on the inner layer and a hydrophobic area on the outer layer. According to the method disclosed by the invention, the zinc negative electrode is immersed in the electrolyte containing citric acid for electrochemical pre-cycle treatment, citric acid molecules are triggered to be spontaneously adsorbed and coupled on the zinc surface, and the citric acid (CA) realizes in-situ construction of a'zincophilic-hydrophobic 'bifunctional interface in a breakthrough manner by virtue of a tricarboxyl-hydroxyl unique molecular structure of the citric acid (CA); and a continuously covered zinc-philic-hydrophobic interface layer is formed, so that the electrochemical activity of the zinc negative electrode of the water-based zinc ion battery can be remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage technology, specifically relating to a self-protection method and system for the zinc anode interface of an aqueous zinc-ion battery. Background Technology

[0002] Aqueous zinc-ion batteries (AZIBs) have become an ideal choice for large-scale energy storage due to their high safety, low cost (zinc price ≈ $2.5 / kg), and large theoretical capacity (820mAh / g). However, the zinc anode faces two major critical interface problems: Zn 2+ Uneven deposition leads to uncontrolled dendrite growth, which pierces the diaphragm and causes a short circuit. Water molecules react with zinc (Zn + 2H2O → Zn(OH)2 + H2↑), resulting in hydrogen evolution and passivation layer accumulation, severe interfacial corrosion, and a sharp drop in coulombic efficiency.

[0003] Constructing artificial interface layers is a fundamental solution, but existing technologies face bottlenecks. Physical coatings such as ZnO@C and MXene coatings suffer from complex processes, weak interfacial bonding, and hindered ion diffusion. Electrolyte additives like MnSO4 and PEG200 offer limited functionality. In-situ interface layers such as ZnF2 and Zn3(PO4)2, on the other hand, are rigid and prone to cracking, cannot be dynamically repaired, and increase interfacial impedance. Summary of the Invention

[0004] The purpose of this invention is to provide a self-protection method and system for the zinc anode interface of an aqueous zinc-ion battery, in order to solve the technical problem of poor electrochemical activity of the zinc anode in existing aqueous zinc-ion batteries.

[0005] To achieve the above objectives, the present invention employs the following technical solution: This invention discloses a self-protection method for the zinc anode interface of an aqueous zinc-ion battery, comprising the following steps: The zinc anode is immersed in an electrolyte containing citric acid for electrochemical pre-cycling treatment, and then a continuous zinc-hydrophobic interface layer is formed on the surface of the zinc anode; the continuous zinc-hydrophobic interface layer includes an inner zinc-loving region and an outer hydrophobic region.

[0006] Furthermore, the concentration of citric acid in the citric acid-containing electrolyte is 0.5~10 mM.

[0007] Furthermore, during the electrochemical pre-cycling treatment, the current density is 1~5 mA / cm². 2 .

[0008] Furthermore, during the electrochemical pre-cycling treatment, the number of cycles is 2 to 5.

[0009] Furthermore, the thickness of the zinc-hydrophobic interface layer is 5~50 nm.

[0010] Furthermore, the thickness of the zinc-hydrophobic interface layer is 20~30nm.

[0011] Furthermore, the zinc-loving region has a Zn-O bonded structure.

[0012] Furthermore, the hydrophobic region has a carboxyl group oriented arrangement structure.

[0013] Furthermore, the contact angle of the zinc-hydrophobic interface layer is ≥100°.

[0014] The present invention also discloses a self-protection system for the zinc anode interface of an aqueous zinc-ion battery for implementing the above-mentioned protection method.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses a self-protection method for the zinc anode interface of an aqueous zinc-ion battery. By immersing the zinc anode in an electrolyte containing citric acid and performing electrochemical pre-cycling treatment, the spontaneous adsorption and coupling of citric acid molecules on the zinc surface are triggered. Citric acid (CA), with its unique tricarboxylic acid-hydroxyl molecular structure, achieves a breakthrough in the in-situ construction of a "zinc-loving-hydrophobic" bifunctional interface, forming a continuously covered zinc-loving-hydrophobic interface layer. Moreover, the continuously covered zinc-loving-hydrophobic interface layer includes an inner zinc-loving region and an outer hydrophobic region, which can significantly improve the electrochemical activity of the zinc anode of the aqueous zinc-ion battery.

[0016] Furthermore, the zincophilic-hydrophobic interface layer includes the inner zincophilic region where Zn-O covalent bonds induce Zn... 2+ Uniform nucleation and oriented growth of (002) crystal planes; the close packing of carboxyl groups in the hydrophobic region increases the contact angle between the electrolyte and the electrode sheet, blocks the contact of active H2O, and effectively reduces the corrosion current.

[0017] Furthermore, the constructed continuously covered zinc-hydrophobic interface layer exhibits dynamic self-healing properties, with unreacted -COOH continuously capturing free Zn. 2+ This method repairs interface defects while using hydrophobic chains to flexibly buffer volumetric strain and prevent brittle cracking. The interface self-assembles in situ, resulting in a simple, low-cost fabrication process that is easy for large-scale production.

[0018] Furthermore, based on relevant experimental results, the method of this invention achieves a yield of 10 mA / cm². 2 20 mAh / cm 2 Under these conditions, the cycle life of Zn / / Zn symmetric cells is ≥3000 h; at 40 mA / cm², the cycle life is ≥3000 h. 2 40 mAh / cm 2Under high load, the capacity does not decrease after cycling for ≥700 h; the Zn / / NaV3O8·1.5H2O (NVOH) full cell retains ≥62% capacity after 1000 cycles at 5 A / g. Attached Figure Description

[0019] Figure 1 A comparison chart of contact angle tests for zinc sulfate electrolyte (ZSO) and zinc sulfate plus citric acid composite electrolyte (ZSO+CA); Figure 2 A comparison of the inhibition effects of ZSO+CA electrolyte and ZSO electrolyte on the byproduct Zn4SO4(OH)6·xH2O; Figure 3 Here are SEM images of the zinc anode surface in different electrolytes; Wherein: a-ZSO electrolyte; b-ZSO+CA electrolyte; Figure 4 XPS characterization comparison of zinc anode surfaces in different electrolytes; Among them: C 1s spectrum in a-ZSO electrolyte; O 1s spectrum in b-ZSO electrolyte; C 1s spectrum in c-ZSO+CA electrolyte; O 1s spectrum in d-ZSO+CA electrolyte; Figure 5 Comparison of cycle performance of Zn / / Zn symmetric cells in different electrolytes; Figure 6 Comparison of the cycling performance of Zn / / Zn symmetric cells in different electrolytes at high current densities; Figure 7 The graph shows the cycling performance of the Zn / / NaV3O8·1.5H2O (NVOH) full cell at 5 A / g. Detailed Implementation

[0020] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0021] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0022] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0023] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0024] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0025] This invention provides a self-protection method for the zinc anode interface of an aqueous zinc-ion battery, comprising the following steps: The zinc negative electrode is immersed in an electrolyte containing citric acid (CA) for electrochemical pre-cycling treatment. This triggers the spontaneous adsorption and coupling of citric acid molecules on the zinc surface, forming a continuous zinc-loving-hydrophobic interface layer. The interface layer comprises an inner zinc-loving region (Zn-O bonded structure) and an outer hydrophobic region (carboxyl groups oriented), with a contact angle ≥100°.

[0026] Preferably, the pre-cycling conditions are: current density 1~5 mA / cm². 2 The number of cycles is 2 to 5. The thickness of the interface layer is 5~50 nm.

[0027] Preferably, the concentration of citric acid in the electrolyte is 0.5~10 mM.

[0028] At 10 mA / cm 2 20 mAh / cm 2 Below, the cycle life of Zn / / Zn symmetric cells is ≥3000 h; At 40 mA / cm 2 40 mAh / cm 2 No capacity decay after cycling for ≥700 hours under high load; The Zn / / NaV3O8·1.5H2O (NVOH) full cell retains ≥62% capacity after 1000 cycles at 5 A / g.

[0029] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0030] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0031] Example 1 A self-protection method for the zinc anode interface of an aqueous zinc-ion battery includes the following steps: The zinc anode was immersed in a 0.5 mM citric acid-containing electrolyte for electrochemical pre-cycling treatment, subsequently forming a continuous zinc-philic-hydrophobic interface layer on the zinc anode surface; the current density during the electrochemical pre-cycling treatment was 1 mA / cm². 2 The number of cycles is 3; the thickness of the zinc-hydrophobic interface layer is 20 nm.

[0032] Example 2 A self-protection method for the zinc anode interface of an aqueous zinc-ion battery includes the following steps: The zinc anode was immersed in a 3 mM citric acid-containing electrolyte for electrochemical pre-cycling treatment, subsequently forming a continuous zinc-philic-hydrophobic interface layer on the zinc anode surface; the current density during the electrochemical pre-cycling treatment was 3 mA / cm². 2 The number of cycles is 1; the thickness of the zinc-hydrophobic interface layer is 30 nm.

[0033] Example 3 A self-protection method for the zinc anode interface of an aqueous zinc-ion battery includes the following steps: The zinc anode was immersed in a 0.5 mM citric acid-containing electrolyte for electrochemical pre-cycling treatment, subsequently forming a continuous zinc-philic-hydrophobic interface layer on the zinc anode surface; the current density during the electrochemical pre-cycling treatment was 1 mA / cm². 2 The number of cycles is 5; the thickness of the zinc-hydrophobic interface layer is 5 nm.

[0034] Example 4 A self-protection method for the zinc anode interface of an aqueous zinc-ion battery includes the following steps: The zinc anode was immersed in a 10 mM citric acid-containing electrolyte for electrochemical pre-cycling treatment, subsequently forming a continuous zinc-philic-hydrophobic interface layer on the zinc anode surface; the current density during the electrochemical pre-cycling treatment was 5 mA / cm². 2 The number of cycles is 2; the thickness of the zinc-hydrophobic interface layer is 50 nm.

[0035] Figure 1 This is a comparison of the contact angle tests of zinc sulfate electrolyte (ZSO) and zinc sulfate plus citric acid composite electrolyte (ZSO+CA) in Example 1. Figure 1 It can be seen that the contact angle of ZSO+CA electrolyte is ≥100°, which is significantly greater than that of ZSO electrolyte, indicating its good wettability, which is conducive to reducing the free energy of zinc metal interface and uniform deposition of zinc ions.

[0036] Figure 2 This is a comparison chart of the inhibition effects of ZSO+CA electrolyte and ZSO electrolyte on the byproduct Zn4SO4(OH)6·xH2O in Example 1. Figure 2 It is evident that the XRD peak of the byproduct at around 8° is significantly weakened, indicating that the ZSO+CA electrolyte effectively inhibits the generation of byproducts.

[0037] Figure 3 These are surface SEM images of the zinc anode in different electrolytes from Example 1. Figure 3 As can be seen, many uneven thin flakes were observed on the surface of the zinc anode in the ZSO electrolyte. Figure 3 a). However, the zinc surface remained smooth in the ZSO+CA electrolyte and exhibited a regular array morphology ( Figure 3 b). This comparison further confirms the effectiveness of ZSO+CA electrolyte in inhibiting corrosion on the zinc anode surface.

[0038] Figure 4 This is a comparison of XPS characterization of the zinc anode surface in different electrolytes in Example 1, from... Figure 4 As can be seen, XPS analysis was used to analyze the composition of the self-built interface after CA molecule adsorption in order to identify the zinc-electrolyte interface. For ZSO electrolyte, the C 1s spectrum only showed the CC / CH and CO bonds ( Figure 4 a). However, Figure 4 The C 1s spectrum of c shows that the carboxyl group of the CA molecule in the ZSO+CA electrolyte derives an additional O=CO bond, indicating that CA exists at the zinc / electrolyte interface. Furthermore, for the O 1s spectrum, only Zn-O bonds were detected in the ZSO electrolyte. Figure 4 b), while Zn-O bonds and O=CO bonds were detected in ZSO+CA electrolyte (b), Figure 4d) further confirms that CA participated in the self-construction of the protection interface.

[0039] Figure 5 This is a comparison of the cycle performance of Zn / / Zn symmetric cells in different electrolytes in Example 1. From... Figure 5 It can be seen that the ZSO+CA electrolyte at 10 mA cm⁻¹ -2 and 20 mAh cm -2 It achieved a long cycle life of 3000 hours. However, under the same conditions using ZSO electrolyte, a short circuit occurred after 100 cycles.

[0040] Figure 6 This is a comparison of the cycling performance of Zn / / Zn symmetric cells in different electrolytes under high current density in Example 1. Figure 6 It can be seen that at a high current density of 40 mA cm⁻¹ -2 and 40 mAh cm -2 Under these conditions, the ZSO+CA electrolyte also exhibited better cycle durability, with no significant capacity decay over ≥700 h.

[0041] Figure 7 This is a cycling performance graph of the Zn / / NaV3O8·1.5H2O(NVOH) full cell in Example 1 at 5 A / g. From... Figure 7 It is evident that the Zn / / NOVH full cell retains 62.68% of its capacity after 1000 cycles, which is significantly higher than the capacity retention of the full cell without CA (4.63%). This indicates that CA plays a crucial role in maintaining the cycle stability of the Zn / / NOVH full cell.

[0042] This invention utilizes electrochemical pre-cycling to trigger the spontaneous adsorption and coupling of citric acid on the zinc anode surface, forming a bifunctional interface layer that combines a zinc-loving region (Zn-O bond anchoring) and a hydrophobic region (carboxyl group-directed H2O blocking). This interface layer achieves corrosion suppression (contact angle ≥100°), enabling Zn / / Zn symmetric cells to achieve a lifetime exceeding 3000 h@20 mA / cm². 2 The capacity retention rate of the full battery after 1000 cycles is >62%.

[0043] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for self-protection of the zinc anode interface in an aqueous zinc-ion battery, characterized in that, Includes the following steps: The zinc anode is immersed in an electrolyte containing citric acid for electrochemical pre-cycling treatment, and then a continuous zinc-hydrophobic interface layer is formed on the surface of the zinc anode; the continuous zinc-hydrophobic interface layer includes an inner zinc-loving region and an outer hydrophobic region.

2. The self-protection method for the zinc anode interface of an aqueous zinc-ion battery according to claim 1, characterized in that, The concentration of citric acid in the electrolyte containing citric acid is 0.5~10 mM.

3. A self-protection method for the zinc anode interface of an aqueous zinc-ion battery according to claim 1, characterized in that, During the electrochemical pre-cycling treatment, the current density is 1~5 mA / cm². 2 .

4. The self-protection method for the zinc anode interface of an aqueous zinc-ion battery according to claim 1, characterized in that, During the electrochemical pre-cycling treatment, the number of cycles is 2 to 5.

5. A self-protection method for the zinc anode interface of an aqueous zinc-ion battery according to claim 1, characterized in that, The thickness of the zinc-hydrophobic interface layer is 5~50 nm.

6. The self-protection method for the zinc anode interface of an aqueous zinc-ion battery according to claim 1, characterized in that, The thickness of the zinc-hydrophobic interface layer is 20~30nm.

7. The self-protection method for the zinc anode interface of an aqueous zinc-ion battery according to claim 1, characterized in that, The zinc-loving region has a Zn-O bonded structure.

8. The self-protection method for the zinc anode interface of an aqueous zinc-ion battery according to claim 1, characterized in that, The hydrophobic region has a carboxyl group oriented arrangement structure.

9. A self-protection method for the zinc anode interface of an aqueous zinc-ion battery according to claim 1, characterized in that, The contact angle of the zinc-hydrophobic interface layer is ≥100°.

10. A self-protection system for the zinc anode interface of an aqueous zinc-ion battery, characterized in that, Used to implement the protection method according to any one of claims 1 to 9.

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