Zinc negative electrode composite interface layer and preparation method and application thereof

Abstract

The invention provides a zinc negative electrode composite interface layer as well as a preparation method and application thereof. The composite interface layer comprises organic salt and inorganic salt, the organic salt is selected from any one or two of alginate and hyaluronate; the inorganic salt is selected from any one or two of bicarbonate and carbonate. The composite interface layer has high mechanical performance, can prolong the protection of the interface on the zinc negative electrode while isolating water molecules, effectively reduces the possibility of decomposition or rupture of the zinc negative electrode, achieves the effect of improving the stability of the zinc negative electrode, further promotes ion transmission, improves the zinc ion deposition mode, and improves the service life of the zinc negative electrode. And the formation of by-products and zinc dendrites is greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of aqueous zinc-ion battery anode technology, and in particular to a zinc anode composite interface layer, its preparation method, and its applications. Background Technology

[0002] Aqueous zinc-ion batteries, by eliminating flammable organic electrolytes and expensive cathode materials, possess significant environmental and economic advantages. Their aqueous electrolyte is non-toxic and non-flammable, exhibits superior ionic conductivity compared to organic electrolytes, enables rapid charging and high power density, and demonstrates outstanding resistance to mechanical stress and electrical abuse, making them a promising candidate for sustainable and efficient energy storage technology. Aqueous zinc-ion batteries use metallic zinc as the anode, which boasts a low redox potential, abundant reserves, and low cost. Its divalent redox chemistry endows it with extremely high volumetric and gravimetric capacity, and it is easily processed at room temperature, exhibiting good stability in acidic and alkaline electrolytes. Early research focused on cathode design, with transition metal oxides (such as manganese-based and vanadium-based oxides) becoming mainstream due to their excellent electrochemical performance. Alternative materials such as hexacyanoferrate derivatives were also explored. Recent research has expanded to comprehensive performance optimization, including anode modification and separator improvement.

[0003] However, aqueous zinc-ion battery anodes face challenges such as dendrite growth, hydrogen evolution reaction, passivation, limited reversibility, and Zn. 2+ Challenges such as slow diffusion are crucial for technological advancement. To address these difficulties, numerous electrode-electrolyte interface technologies have been developed and applied to zinc-ion batteries. These technologies effectively isolate the electrolyte and the zinc metal anode to suppress side reactions, thereby improving cycle life and efficiency. However, this strategy still faces challenges in formation and stability. Zinc anodes are prone to dendrite formation during cycling, especially when the interface layer is unstable. Dendrites can pierce the interface layer, causing short circuits. Due to insufficient interface layer stability, direct contact between water molecules in the electrolyte and zinc cannot be prevented, leading to corrosion of the zinc anode, decreased coulombic efficiency, and battery failure. Some artificial interface layers also suffer from weak physical contact or chemical bonding with the zinc anode. Therefore, exploring simple and convenient formation mechanisms and self-renewing solid-state electrolyte interfaces is essential. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a zinc anode composite interface layer, its preparation method and application, to solve the problems of poor mechanical properties, inability to suppress side reactions, insufficient stability and slow zinc ion transport caused by the interface layer in the prior art.

[0005] To achieve the above and other related objectives, the present invention provides a zinc anode composite interface layer, its preparation method, and its uses.

[0006] The first aspect of the present invention provides a composite interface layer for modifying a zinc anode. The composite interface layer comprises an organic salt and an inorganic salt; the organic salt is selected from any one or two of alginate and hyaluronic acid salt; and the inorganic salt is selected from any one or two of bicarbonate and carbonate.

[0007] Preferably, the alginate is selected from any one or more of sodium alginate, potassium alginate, and ammonium alginate.

[0008] Preferably, the hyaluronic acid salt is selected from any one or more of sodium hyaluronate, potassium hyaluronate, zinc hyaluronate, and calcium hyaluronate.

[0009] Preferably, the bicarbonate is selected from any one or two of sodium bicarbonate and potassium bicarbonate.

[0010] Preferably, the carbonate is selected from any one or two of sodium carbonate and potassium carbonate.

[0011] More preferably, the organic salt is an alginate.

[0012] More preferably, the organic salt is sodium alginate.

[0013] More preferably, the inorganic salt is a bicarbonate.

[0014] More preferably, the inorganic salt is potassium bicarbonate.

[0015] Preferably, the mass ratio of the organic salt to the inorganic salt is 1:(0.1 to 10).

[0016] More preferably, the mass ratio of the organic salt to the inorganic salt is 1:(0.1-5).

[0017] More preferably, the mass ratio of the organic salt to the inorganic salt is 1:(0.5 to 1.5); including but not limited to 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1.0, 1:1.2, 1:1.3, 1:1.4 or 1:1.5.

[0018] Preferably, the weight-average molecular weight of the alginate is 200-300 kDa; for example, it can be 200 kDa, 210 kDa, 220 kDa, 230 kDa, 240 kDa, 250 kDa, 260 kDa, 270 kDa, 280 kDa, 290 kDa or 300 kDa.

[0019] Preferably, the number average molecular weight of the hyaluronic acid salt is 1000 kDa to 2000 kDa; for example, it can be 1000 kDa, 1100 kDa, 1200 kDa, 1300 kDa, 1400 kDa, 1500 kDa, 1600 kDa, 1700 kDa, 1800 kDa, 1900 kDa or 2000 kDa.

[0020] A second aspect of the present invention provides a zinc anode modified with a composite interface layer, comprising the above-described composite interface layer and a zinc substrate, wherein the composite interface layer is coated on the surface of the zinc substrate.

[0021] Preferably, the thickness of the zinc substrate is 30-100 μm.

[0022] More preferably, the thickness of the zinc substrate is 40-80 μm; for example, it can be 40 μm, 50 μm, 60 μm, 70 μm or 80 μm.

[0023] Preferably, the coating thickness is 10-100 μm.

[0024] More preferably, the coating thickness is 10-50 μm; for example, it can be 10 μm, 20 μm, 30 μm, 40 μm or 50 μm.

[0025] Preferably, the coating is applied by scraping or spin coating.

[0026] Preferably, the coating is a full coating, so that the composite interface layer completely covers the zinc substrate.

[0027] A third aspect of the present invention provides a method for preparing the above-mentioned composite interface layer modified zinc anode, the method comprising: dissolving an organic salt and an inorganic salt in water to form an organic-inorganic salt composite aqueous solution; coating the organic-inorganic salt composite aqueous solution onto the surface of a zinc substrate, and drying it by heating to obtain a composite interface layer modified zinc anode.

[0028] Preferably, the concentration of organic salt in the organic-inorganic salt composite aqueous solution is 10-100 mg / mL.

[0029] More preferably, the concentration of the organic salt in the organic-inorganic salt composite aqueous solution is 10-50 mg / mL; for example, it can be 10 mg / mL, 20 mg / mL, 30 mg / mL, 40 mg / mL or 50 mg / mL.

[0030] Preferably, the concentration of inorganic salt in the organic-inorganic salt composite aqueous solution is 10-100 mg / mL.

[0031] More preferably, the concentration of inorganic salt in the organic-inorganic salt composite aqueous solution is 10-50 mg / mL; for example, it can be 10 mg / mL, 20 mg / mL, 30 mg / mL, 40 mg / mL or 50 mg / mL.

[0032] Preferably, the areal capacity of the organic-inorganic salt composite aqueous solution coating is 10-100 μL cm⁻¹. -2 .

[0033] More preferably, the areal capacity of the organic-inorganic salt composite aqueous solution coating is 10-50 μL cm⁻¹. -2 For example, it can be 10 μL cm -2 15μL cm -2 20μL cm -2 25μL cm -2 30μL cm -2 35μL cm -2 40μL cm -2 45μLcm -2 50μL cm -2 .

[0034] More preferably, the areal capacity of the organic-inorganic salt composite aqueous solution coating is 10-20 μL cm⁻¹. -2 For example, it can be 10 μL cm -2 11μL cm -2 12μL cm -2 13μL cm -2 14μL cm -2 15μL cm -2 16μL cm -2 17μL cm -2 18μL cm -2 19μL cm -2 Or 20μL cm -2 .

[0035] Preferably, the zinc substrate is a pretreated zinc sheet, and the pretreatment includes grinding and impurity removal.

[0036] More preferably, the polishing is done by using sandpaper to remove oxides from the surface of the zinc sheet.

[0037] More preferably, the impurity removal is performed by wiping or cleaning the surface of the zinc sheet with ethanol or water to remove impurities from the zinc sheet surface.

[0038] Preferably, the drying temperature is 40-80℃; for example, it can be 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃ or 80℃.

[0039] Preferably, the drying time is 0.5 to 2 hours.

[0040] More preferably, the drying time is 0.5 to 1 hour; for example, it can be 0.5 hours, 0.6 hours, 0.7 hours, 0.8 hours, 0.9 hours, or 1 hour.

[0041] The fourth aspect of the present invention provides the use of the zinc anode modified with the above-mentioned composite interface layer as the anode in an aqueous zinc-ion battery.

[0042] The fifth aspect of the present invention provides an aqueous zinc-ion battery, comprising a zinc negative electrode modified with the above-described composite interface layer, a positive electrode, a separator, and an electrolyte.

[0043] Preferably, the positive electrode is any one or more of manganese-based oxide, vanadium-based oxide, and Prussian blue.

[0044] More preferably, the manganese-based oxide is MnO2.

[0045] More preferably, the vanadium-based oxide is any one or more selected from vanadium pentoxide, hydrated vanadium pentoxide, and zinc vanadate.

[0046] More preferably, the Prussian blue is any one or more selected from iron-based Prussian blue, manganese-based Prussian blue, and cobalt-based Prussian blue.

[0047] Preferably, the diaphragm is made of glass fiber.

[0048] Preferably, the electrolyte comprises an aqueous solution of zinc salt.

[0049] More preferably, the zinc salt is selected from any one or more of zinc sulfate, zinc chloride, zinc trifluoromethanesulfonate, and zinc acetate.

[0050] More preferably, the electrolyte further includes an aqueous solution of manganese salt.

[0051] More preferably, the manganese salt is selected from any one or more of manganese sulfate, manganese chloride, and manganese acetate.

[0052] Preferably, the aqueous zinc-ion battery is a rechargeable aqueous zinc-ion battery.

[0053] More preferably, the aqueous zinc-ion battery includes button cells, cylindrical cells, sheet cells, and pouch cells.

[0054] As described above, the zinc anode composite interface layer, its preparation method, and its uses according to the present invention have the following beneficial effects:

[0055] 1. This invention successfully constructs an organic-inorganic composite interface layer on the zinc anode surface by pre-coating organic and inorganic components onto the surface, enabling in-situ chemical reactions with zinc ions in the electrolyte. Unlike the solid electrolyte interface formation mechanism in most aqueous zinc-ion batteries, this method constructs a composite interface with high mechanical properties in a more direct and convenient manner. This interface not only isolates water molecules but also extends its protective effect on the zinc anode, effectively reducing the possibility of decomposition or breakage, thereby improving the stability of the zinc anode.

[0056] 2. This invention selects suitable organic components to enable them to effectively coordinate with zinc ions, forming an interface layer on the zinc anode surface through coordination. This layer consists of zinc ions acting as ion bridges and organic matter forming a network cross-linked structure. The zinc ions in this cross-linked structure not only act as cross-linking agents but also as charge carriers, participating in ion transport. Therefore, the cross-linked structure not only provides mechanical support but also promotes ion transport. Simultaneously, it improves the zinc ion deposition method, significantly reducing the formation of byproducts and zinc dendrites.

[0057] 3. During battery cycling, the inorganic components in the constructed interface layer will change, and zinc carbonate will be initially formed through a relatively slow in-situ chemical reaction. It will always exist in the environment of the electrode / electrolyte interface layer to protect the zinc negative electrode and isolate the electrolyte. The zinc carbonate will partially decompose and transform during the charging and discharging process of the battery cycle to achieve self-renewal and repair.

[0058] 4. Using the composite interface layer modified zinc electrode of the present invention, and using the modified zinc electrode to form a symmetrical cell, at a current density of 1 mA cm⁻¹ -2 1mAh capacity for kneading dough -2 The cycle time exceeded 1100 hours; current density 5 mA / cm². -2 2.5mAh capacity for kneading dough -2 The modified zinc-copper battery can withstand over 750 hours of cycling; at a current density of 1 mA / cm², it can withstand over 750 hours of cycling. -2 Dough capacity: 0.5mAh / cm³ -2 The lower coulomb efficiency reaches 99.6%.

[0059] 5. The organic and inorganic materials used in this invention are inexpensive, environmentally friendly, readily available, safe, non-toxic, and easy to apply in industrial applications. Attached Figure Description

[0060] Figure 1 The image shows a symmetrical battery prepared in Example 1 and Comparative Example 1 in Example 7 of the present invention at a current density of 1 mA / cm².2 The surface capacity is 1mAh / cm². 2 The test results of the cycle performance under the conditions; where Bare Zn||Zn represents the symmetrical cell of Comparative Example 1, and BZC / ZCZH / SA@Zn||Zn represents the symmetrical cell of Example 1.

[0061] Figure 2 The image shows a symmetrical battery prepared in Example 4 of this invention at a current density of 1 mA / cm². 2 The surface capacity is 1mAh / cm². 2 Results of cyclic performance tests under the specified conditions.

[0062] Figure 3 The image shows a symmetrical battery prepared in Example 5 of the present invention in Example 7 at a current density of 1 mA / cm². 2 The surface capacity is 1mAh / cm². 2 Results of cyclic performance tests under the specified conditions.

[0063] Figure 4 The image shows a symmetrical battery prepared in Example 6 in Example 7 of this invention at a current density of 1 mA / cm². 2 The surface capacity is 1mAh / cm². 2 Results of cyclic performance tests under the specified conditions.

[0064] Figure 5 The image shows a symmetrical battery prepared in Example 1 in Example 7 of this invention at a current density of 5 mA / cm². 2 The surface capacity is 2.5mAh / cm². 2 Cyclic performance test results under the specified conditions; among which, Figure 5 (Left) shows the charge-discharge cycle test results of the symmetrical battery in Example 1 over 800 hours. Figure 5 (Right) represents the charge-discharge test results of the symmetrical battery of Example 1 between 750h and 760h.

[0065] Figure 6 The image shows a symmetrical battery prepared in Example 2 of this invention at a current density of 5 mA / cm². 2 The surface capacity is 2.5mAh / cm². 2 Cyclic performance test results under the specified conditions; among which, Figure 6 (Left) shows the charge-discharge cycle test results of the symmetrical battery in Example 2 over 450 hours. Figure 6 (Right) represents the charge-discharge test results of the symmetrical battery of Example 2 between 410h and 420h.

[0066] Figure 7 The image shows a symmetrical battery prepared in Example 3 of this invention at a current density of 5 mA / cm².2 The surface capacity is 2.5mAh / cm². 2 Cyclic performance test results under the specified conditions; among which, Figure 7 (Left) shows the charge-discharge cycle test results of the symmetrical battery in Example 3 over 500 hours. Figure 7 (Right) represents the charge-discharge test results of the symmetrical battery of Example 3 between 450h and 460h.

[0067] Figure 8 The image shows the full cells prepared in Example 1 and Comparative Example 1 in Example 7 of this invention at a mass current density of 1 Ag. -1 The results of long-cycle performance tests under the specified conditions; where the horizontal axis represents the number of cycles, the vertical axis represents the specific capacity (left) and coulombic efficiency (right), Bare Zn||MnO2 represents a full cell assembled with unmodified zinc sheets, and BZC / ZCZH / SA@Zn||MnO2 represents a full cell assembled with zinc sheets modified with a composite interface layer.

[0068] Figure 9 The illustration shows the modified zinc sheet from Example 1 in Example 8 of the present invention at a current density of 1 mA / cm². 2 The surface capacity is 1mAh / cm². 2 The surface morphology was observed using a scanning electron microscope after 20 cycles of charge and discharge under certain conditions.

[0069] Figure 10 The image shows the unmodified zinc sheet from Comparative Example 1 in Example 8 of this invention at a current density of 1 mA / cm². 2 The surface capacity is 1mAh / cm². 2 The surface morphology was observed using a scanning electron microscope after 20 cycles of charge and discharge under certain conditions.

[0070] Figure 11 The figure shown is a Tafel curve for studying the corrosion resistance of the modified zinc sheet in Example 1 and the unmodified zinc sheet in Comparative Example 1 in Example 8 of the present invention; wherein, Bare Zn represents the unmodified zinc sheet, and BZC / ZCZH / SA@Zn represents the zinc sheet modified with a composite interface layer.

[0071] Figure 12 The results of mechanical property testing of the unmodified zinc sheet in Comparative Example 1 using atomic force microscopy in Example 8 of the present invention are shown; where the horizontal axis represents distance and the vertical axis represents the corresponding Young's modulus.

[0072] Figure 13 The results of mechanical property testing of the modified zinc sheet in Example 1 using an atomic force microscope are shown in Example 8 of the present invention; where the horizontal axis represents distance and the vertical axis represents the corresponding Young's modulus.

[0073] Figure 14 The figures shown are the coulombic efficiency test results of zinc-copper batteries assembled using the modified zinc sheet from Example 1 and the unmodified zinc sheet from Comparative Example 1, respectively, in Example 8 of the present invention; wherein, Bare Cu||Zn represents the zinc-copper battery prepared using the unmodified zinc sheet from Comparative Example 1, and BZC / ZCZH / SA@Cu||Zn represents the zinc-copper battery prepared using the modified zinc sheet from Example 1. Detailed Implementation

[0074] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0075] It should be noted that the process equipment or apparatus not specifically mentioned in the following embodiments are all conventional equipment or apparatus in the art.

[0076] Furthermore, it should be understood that the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, does not preclude the presence of other method steps before or after the combined steps, unless otherwise stated. It should also be understood that the combined connection relationship between one or more devices / apparatus mentioned in this invention does not preclude the existence of other devices / apparatus before or after the combined devices / apparatus, or the insertion of other devices / apparatus between these explicitly mentioned devices / apparatus. Moreover, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or defining the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0077] Before further describing specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terminology used in the embodiments of the present invention is for describing specific embodiments and not for limiting the scope of protection of the present invention; in the specification and claims of the present invention, unless otherwise expressly stated in the text, the singular forms "a", "an" and "this" include the plural forms.

[0078] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. In addition to the specific methods, apparatus, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description of this invention, any prior art methods, apparatus, and materials similar to or equivalent to those described, apparatus, and materials in the embodiments of this invention may be used to implement the present invention.

[0079] Aqueous zinc-ion batteries are a new type of rechargeable battery that uses zinc as the negative electrode material and water or an aqueous electrolyte as the electrolyte. They offer advantages such as high energy density, high safety, and environmental friendliness. The working principle is as follows: When the battery discharges, zinc atoms lose electrons and undergo oxidation. Zinc atoms enter the electrolyte as ions, while the released electrons flow to the positive electrode through the external circuit, thus forming an electric current. During charging, under the influence of an external power source, electrons flow from the positive electrode to the negative electrode. Zinc ions are released from the positive electrode material's crystal lattice, enter the electrolyte, and migrate to the surface of the negative electrode, where they are redeposited as zinc metal. Through this charging and discharging process, aqueous zinc-ion batteries achieve the interconversion of chemical energy and electrical energy.

[0080] Charging process (zinc ions deposit on the positive electrode surface to form a zinc layer) Zn 2+ +2e - →Zn;

[0081] Discharge process (zinc layer dissolves from the positive electrode surface to form zinc ions) Zn→Zn 2+ +2e - .

[0082] To suppress various side reactions (zinc dendrite formation, hydrogen evolution, etc.) during the charging and discharging process of aqueous zinc-ion batteries, the applicant of this application has coated the zinc anode surface with specific organic and inorganic components. Through the in-situ chemical reaction between the two components and zinc ions in the electrolyte, an organic-inorganic composite interface layer is constructed on the zinc anode surface. This composite interface layer possesses high mechanical properties. The organic component of this application, through coordination with zinc ions, forms an interface layer on the zinc anode surface with zinc ions acting as ion bridges and forming a network cross-linked structure with organic matter. The zinc ions in this cross-linked structure not only act as cross-linking agents but also as charge carriers, participating in ion conduction. The inorganic component of this application, through in-situ chemical reaction with zinc ions, forms zinc carbonate. The zinc carbonate is fixed on the electrode surface through the organic network cross-linked structure, thereby isolating the zinc anode from the electrolyte. During the charging and discharging process of the battery cycle, some of the zinc carbonate decomposes and transforms, achieving self-renewal and repair.

[0083] Example 1

[0084] This embodiment 1 provides a specific composite interface-modified zinc sheet, and the zinc sheet is used as the positive and negative electrodes, or the zinc sheet is used as the negative electrode and MnO2 is used as the positive electrode, and it is assembled with a separator and electrolyte to form a symmetrical battery or a full battery. The specific preparation method includes the following steps:

[0085] A commercial zinc disc with a diameter of 16 mm and a thickness of approximately 50 μm was sanded to remove surface oxides, wiped with ethanol, and then dried for later use. 0.4 g of sodium alginate powder (weight-average molecular weight 270,000 Da) and 0.4 g of potassium bicarbonate powder were dissolved in 20 mL of deionized water and stirred thoroughly for 4 h to obtain a sodium alginate-potassium bicarbonate composite aqueous solution. 50 μL of the sodium alginate-potassium bicarbonate composite aqueous solution was dropped onto the treated commercial zinc disc, and a coating scraper was used to evenly coat the zinc disc. The coated zinc disc was then dried in a vacuum drying oven at 70 °C for 40 min to obtain a composite interface-modified zinc disc with a coating thickness of approximately 20 μm.

[0086] Furthermore, using the aforementioned composite interface layer modified zinc sheet as the positive and negative electrodes, glass fiber (GF / D, average pore size 2.7 μm, thickness 50 μm) as the separator, and 2M zinc sulfate aqueous solution as the electrolyte, a CR2032 type symmetrical cell was assembled.

[0087] Furthermore, using the aforementioned composite interface layer modified zinc sheet as the negative electrode, MnO2 as the positive electrode, glass fiber as the separator, and a mixed aqueous solution of 2M zinc sulfate and 0.2M manganese sulfate as the electrolyte, a CR2032 type full cell was assembled.

[0088] Example 2

[0089] This embodiment 2 provides a specific composite interface modified zinc sheet, and the zinc sheet is used as the positive and negative electrode, or the zinc sheet is used as the negative electrode and MnO2 is used as the positive electrode, and it is assembled with a separator and electrolyte to form a symmetrical battery or a full battery. The difference between this embodiment 2 and embodiment 1 is that the amount of potassium bicarbonate powder added is increased from 0.4g to 0.6g in the preparation process of the composite interface, while the amount of other substances added and the preparation method are the same as in embodiment 1.

[0090] Example 3

[0091] This embodiment 3 provides a specific composite interface modified zinc sheet, and the zinc sheet is used as the positive and negative electrode, or the zinc sheet is used as the negative electrode and MnO2 is used as the positive electrode, and it is assembled with a separator and electrolyte to form a symmetrical battery or a full battery. The difference between this embodiment 3 and embodiment 1 is that the amount of potassium bicarbonate powder added is reduced from 0.4g to 0.2g in the preparation process of the composite interface, while the amount of other substances added and the preparation method are the same as in embodiment 1.

[0092] Example 4

[0093] This embodiment 4 provides a specific composite interface modified zinc sheet, and the zinc sheet is used as the positive and negative electrode, or the zinc sheet is used as the negative electrode and MnO2 is used as the positive electrode, and it is assembled with a separator and electrolyte to form a symmetrical battery or a full battery. The difference between this embodiment 4 and embodiment 1 is that potassium bicarbonate powder is replaced with sodium bicarbonate powder in the preparation process of the composite interface, and the amount of other substances added and the preparation method are the same as in embodiment 1.

[0094] Example 5

[0095] This embodiment 5 provides a specific composite interface modified zinc sheet, and the zinc sheet is used as the positive and negative electrode, or the zinc sheet is used as the negative electrode and MnO2 is used as the positive electrode, and it is assembled with a separator and electrolyte to form a symmetrical battery or a full battery. The difference between this embodiment 5 and embodiment 1 is that potassium bicarbonate powder is replaced with potassium carbonate powder in the preparation process of the composite interface, and the amount of other substances added and the preparation method are the same as in embodiment 1.

[0096] Example 6

[0097] This embodiment 6 provides a specific composite interface modified zinc sheet, and the zinc sheet is used as the positive and negative electrode, or the zinc sheet is used as the negative electrode and MnO2 is used as the positive electrode, and it is assembled with a separator and electrolyte to form a symmetrical battery or a full battery. The difference between this embodiment 6 and embodiment 1 is that sodium alginate powder is replaced with sodium hyaluronate powder (number average molecular weight 1,500,000 Da) in the preparation process of the composite interface, while the amount of other substances added and the preparation method are the same as in embodiment 1.

[0098] Comparative Example 1

[0099] Comparative Example 1 uses a single unmodified zinc sheet as both the positive and negative electrodes, or uses the zinc sheet as the negative electrode and MnO2 as the positive electrode, and assembles it together with a separator and electrolyte to form a symmetrical cell or a full cell. The specific preparation method includes the following steps:

[0100] Commercial zinc discs with a diameter of 16 mm and a thickness of approximately 50 μm were sanded to remove surface oxides, wiped with ethanol, and then dried for later use.

[0101] Furthermore, the treated zinc sheet was used as the positive and negative electrodes, glass fiber as the separator, and 2M zinc sulfate aqueous solution as the electrolyte to assemble a CR2032 type symmetrical battery.

[0102] Furthermore, using the treated zinc sheet as the negative electrode, MnO2 as the positive electrode, glass fiber as the separator, and a mixed aqueous solution of 2M zinc sulfate and 0.2M manganese sulfate as the electrolyte, a CR2032 type full cell was assembled.

[0103] Example 7

[0104] Example 7 tests the long-cycle performance of the symmetric cells or full cells prepared in Examples 1-6 and Comparative Example 1.

[0105] First, the symmetrical cells prepared in Examples 1, 4-6, and Comparative Example 1 were tested at a current density of 1 mA / cm². 2 The surface capacity is 1mAh / cm². 2 The long-cycle performance under certain conditions was tested.

[0106] Specifically: The assembled symmetrical battery was clipped onto the NEWARE battery tester, and the constant current charge / discharge mode was selected for testing, with the current density set to 1 mA / cm². 2 The surface capacity is 1mAh / cm². 2 The resting time is 12 hours, and the charging and discharging time is 1 hour each.

[0107] The long-cycle performance of the symmetric cells prepared in Example 1 and Comparative Example 1 is as follows: Figure 1 As shown in the figure, the horizontal axis represents the cycle time, and the vertical axis represents the total potential difference of the battery over time during the test. The change in total potential difference is recorded once for each charge-discharge cycle. The results show that at a current density of 1 mA / cm²... 2 The surface capacity is 1mAh / cm². 2 Under the same conditions, the unmodified symmetric battery in Comparative Example 1 could only operate stably for about 250 hours. Compared with the unmodified symmetric battery in Comparative Example 1, the symmetric battery in Example 1 has better cycle stability and can operate stably for more than 1100 hours. In addition, within 1100 hours, the total potential difference of the symmetric battery in Example 1 during the charging and discharging process can be stably maintained at about 0.05V, proving that it has better cycle capability and is safer.

[0108] The long-cycle performance of the symmetric cells prepared in Examples 4-6 are as follows: Figures 2-4 As shown in the figure, the horizontal axis represents the cycle time, and the vertical axis represents the total potential difference of the battery over time during the test. The change in total potential difference is recorded once for each charge-discharge cycle. The results show that at a current density of 1 mA / cm²... 2The surface capacity is 1mAh / cm². 2 Under the conditions, the symmetric cell prepared in Example 4 ( Figure 2 The battery can operate stably for over 900 hours. Furthermore, within this 900-hour period, the total potential difference of the symmetrical battery in Example 4 during charge and discharge can be stably maintained below 0.1V, demonstrating good cycle capability. The symmetrical battery prepared in Example 5 (… Figure 3 The battery can operate continuously for about 1000 hours. During this period, the total potential difference of the symmetrical battery in Example 5 remains relatively stable during charging and discharging, but it is less stable in the early stages of cycling. The symmetrical battery prepared in Example 6... Figure 4 The device can operate continuously for approximately 1000 hours, maintaining a total potential difference of around 0.05V during charge and discharge, demonstrating good cycle performance. However, the total potential difference tends to decrease and stabilize over time, although it remains relatively unstable in the early stages of cycling. Furthermore, compared to the sodium bicarbonate inorganic salt used in Example 4, the composite interface layer prepared using a sodium alginate-potassium bicarbonate composite aqueous solution in Example 1 provides better protection for the zinc anode. This is because sodium ions have a stronger solvation ability, resulting in a higher desolvation barrier. Compared to the sodium hyaluronate organic salt used in Example 6, the composite interface layer prepared using a sodium alginate-potassium bicarbonate composite aqueous solution in Example 1 provides better protection for the zinc anode and exhibits lower voltage hysteresis during cycling. This is because sodium alginate coordinates more easily with zinc ions, and the resulting coordination structure is more conducive to the uniform transport of zinc ions.

[0109] Furthermore, the symmetrical cells prepared in Examples 1-3 were tested at a current density of 5 mA / cm². 2 The surface capacity is 2.5mAh / cm². 2 The long-cycle performance under certain conditions was tested.

[0110] Specifically: The assembled symmetrical battery was clipped onto the NEWARE battery tester, and the constant current charge / discharge mode was selected for testing, with the current density set to 5 mA / cm². 2 The surface capacity is 2.5mAh / cm². 2 The resting time is 12 hours, and the charging and discharging time is 0.5 hours each.

[0111] The long-cycle performance of the symmetric cells prepared in Examples 1-3 is as follows: Figures 5-7 As shown in the figure, the horizontal axis represents the cycle time, and the vertical axis represents the total potential difference of the battery over time during the test. The change in total potential difference is recorded once for each charge-discharge cycle. The results show that at a current density of 5 mA / cm²... 2 The surface capacity is 2.5mAh / cm². 2Under the given conditions, the symmetric batteries prepared in Examples 1 to 3 can all operate stably for more than 400 hours. Furthermore, compared with the symmetric batteries in Examples 2 to 3, the symmetric battery in Example 1 has a smaller total potential difference and a longer cycle life during cycling, and can operate stably for nearly 800 hours. This result proves that the amount of inorganic salt added affects the cycle performance of the battery, and both excessive and insufficient addition will lead to a decrease in its cycle performance.

[0112] Furthermore, the full cells prepared in Example 1 and Comparative Example 1 were compared at a mass current density of 1 Ag. -1 The long-cycle performance under certain conditions was tested.

[0113] Specifically: Clamp the assembled full battery onto the NEWARE battery tester, select the constant current charge / discharge mode for testing, and set the mass current density to 1Ag. -1 The shelf life is 12 hours.

[0114] Test results are as follows Figure 8 As shown in the figure, the horizontal axis represents the number of cycles, and the vertical axis represents the specific capacity (left) and coulombic efficiency (right). Bare Zn||MnO2 represents a full cell assembled with unmodified zinc sheets, and BZC / ZCZH / SA@Zn||MnO2 represents a full cell assembled with zinc sheets modified with a composite interface layer. The results show that at a mass current density of 1 Ag... -1 Under the conditions described, the full cell in Example 1 exhibited higher specific capacity and coulombic efficiency than that in Comparative Example 1 throughout the entire operating process, and maintained a high specific capacity (165.2 mAh g⁻¹) even after 1000 cycles. -1 The capacity decay rate is relatively slow (decay rate <0.05% / cycle), exhibiting good cycle stability; while the full cell in Comparative Example 1 showed a specific capacity decay of 131.04 mAh g after 1000 cycles. -1 The rate of decline is relatively fast, and the cycle stability is poor; in addition, the coulombic efficiency of the full cell in Example 1 remains above 99% throughout the entire working process.

[0115] Example 8

[0116] In this embodiment 8, the surface morphology, corrosion resistance, mechanical properties, and coulombic efficiency of the modified zinc sheet in Example 1 and the unmodified zinc sheet in Comparative Example 1 after operation were tested, respectively, and they were used to assemble zinc-copper batteries.

[0117] First, the surface morphology of the modified zinc sheet in Example 1 and the unmodified zinc sheet in Comparative Example 1 was observed after a certain period of operation. Specifically, the symmetric cells prepared in Example 1 and Comparative Example 1 were observed at a current density of 1 mA / cm². 2 The surface capacity is 1mAh / cm². 2Under the condition of 20 cycles of charge and discharge, the zinc sheet after work was placed under a scanning electron microscope to observe the surface of both.

[0118] The surface of the zinc sheet in Example 1 is as follows Figure 9 As shown, the surface of the zinc sheet in Comparative Example 1 is as follows: Figure 10 As shown, the results indicate that at a current density of 1 mA / cm², 2 The surface capacity is 1mAh / cm². 2 After 20 cycles of charge and discharge under the specified conditions, the zinc sheet with composite interface layer in Example 1 has a relatively flat, dense and uniform surface with almost no dendrite growth and by-product accumulation, while the zinc sheet in Comparative Example 1 is occupied by dendrites and by-products. Therefore, the composite interface of this application can effectively protect the zinc electrode during the operation of the battery and reduce dendrite growth and by-product accumulation caused by uneven deposition.

[0119] Furthermore, the corrosion resistance of the electrodes in Example 1 and Comparative Example 1 was investigated. Specifically, a three-electrode system was assembled, using zinc foil as the working electrode, zinc foil as the counter electrode, Ag / AgCl as the reference electrode, and 2M zinc sulfate solution as the electrolyte. The three-electrode system was tested using the Tafel test mode of a CHI660E electrochemical workstation, with the voltage scan range set to -0.9 to -1.1 V and the scan rate at 1 mV / s.

[0120] The obtained Tafel curve is as follows Figure 11 As shown, Bare Zn represents unmodified zinc sheet, and BZC / ZCZH / SA@Zn represents zinc sheet modified with composite interface layer. The results show that compared with Comparative Example 1, the zinc sheet in Example 1 has a higher corrosion voltage and a lower corrosion current, and the modified zinc sheet has higher corrosion resistance than commercial zinc sheet.

[0121] Furthermore, the mechanical properties of the modified zinc sheet prepared in Example 1 and the zinc sheet in Comparative Example 1 were tested using atomic force microscopy (AFM). Specifically, the zinc sheet was scanned using AFM in quantitative nanomechanical imaging (QNM) mode to obtain Young's modulus data; during the scanning process, the Young's modulus values ​​of the diagonal of the scanned area and the corresponding lateral positions were recorded as follows: Figure 12 (Comparative Example 1) and Figure 13 As shown in Example 1, the horizontal axis represents distance and the vertical axis represents the corresponding Young's modulus. The results show that compared with Comparative Example 1, the modified zinc sheet in Example 1 has a higher Young's modulus, better mechanical properties, and is more resistant to elastic deformation during battery cycling, maintaining a uniform transport channel for zinc ions.

[0122] Furthermore, the modified zinc sheet from Example 1 and the unmodified zinc sheet from Comparative Example 1 were used to assemble zinc-copper batteries, and their coulombic efficiency was tested.

[0123] Specifically: A CR2032 zinc-copper battery was assembled using the modified zinc sheet prepared in Example 1 as the negative electrode, a 16mm diameter copper foil as the positive electrode, glass fiber as the separator, and a 2M zinc sulfate aqueous solution as the electrolyte. The assembled zinc-copper battery was then clamped onto a NEWARE battery tester, and a constant current charge-discharge mode was selected for testing, with a current density set to 1mA / cm². 2 The surface capacity is 0.5mAh / cm³. 2 The resting time is 12 hours, the charging and discharging time is 0.5 hours each, and the cutoff voltage is 0.5V.

[0124] Specific test results are as follows: Figure 14 As shown, Bare Cu||Zn represents the zinc-copper battery prepared using the unmodified zinc sheet in Comparative Example 1, and BZC / ZCZH / SA@Cu||Zn represents the zinc-copper battery prepared using the modified zinc sheet in Example 1. The results show that the zinc-copper battery prepared using the unmodified zinc sheet in Comparative Example 1 can only cycle about 300 times, and the coulombic efficiency during the cycle is unstable and varies greatly; while the zinc-copper battery prepared using the modified zinc sheet in Example 1 can cycle 1200 times, and the coulombic efficiency is stable at about 99.6%, showing higher cycle performance and coulombic efficiency.

[0125] In summary, modifying the zinc anode using the composite interface layer of this application can effectively accelerate zinc ion transport, suppress side reactions (hydrogen evolution reaction, passivation reaction), and promote uniform zinc ion deposition, thereby reducing the accumulation of zinc dendrites and dead zinc on the electrode surface. Simultaneously, due to the self-healing properties of the composite interface layer, it can more effectively isolate the interface from attacks by molecules in the electrolyte and extend its protection time for the electrode, mitigating the possibility of failure and breakage.

[0126] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any form or substance. It should be noted that those skilled in the art can make various improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention. Any modifications, alterations, and equivalent changes made by those skilled in the art based on the above-disclosed technical content without departing from the spirit and scope of the present invention are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and evolutions made to the above embodiments based on the essential technology of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A composite interface layer for modifying zinc anodes, characterized in that, The composite interface layer comprises organic salts and inorganic salts; the organic salts are selected from any one or two of alginate and hyaluronic acid salts; the inorganic salts are selected from any one or two of bicarbonate and carbonate salts.

2. The composite interface layer according to claim 1, characterized in that, The alginate is selected from any one or more of sodium alginate, potassium alginate, and ammonium alginate. And / or, the hyaluronic acid salt is any one or more selected from sodium hyaluronate, potassium hyaluronate, zinc hyaluronate, and calcium hyaluronate; And / or, the bicarbonate is selected from any one or two of sodium bicarbonate and potassium bicarbonate; And / or, the carbonate is selected from any one or two of sodium carbonate and potassium carbonate; And / or, the mass ratio of the organic salt to the inorganic salt is 1:(0.1 to 10); And / or, the weight-average molecular weight of the alginate is 200-300 kDa; And / or, the number average molecular weight of the hyaluronic acid salt is 1000 kDa to 2000 kDa.

3. A zinc anode modified with a composite interface layer, characterized in that, It includes the composite interface layer as described in any one of claims 1 to 2 and a zinc substrate, wherein the composite interface layer is coated on the surface of the zinc substrate.

4. The zinc anode modified with a composite interface layer according to claim 3, characterized in that, The thickness of the zinc substrate is 30-100 μm; And / or, the coating thickness is 10-100 μm; And / or, the coating is applied by scraping or spin coating.

5. A method for preparing a zinc anode modified with a composite interface layer as described in any one of claims 3 or 4, characterized in that, The preparation method includes: dissolving organic salt and inorganic salt in water to form an organic-inorganic salt composite aqueous solution; coating the organic-inorganic salt composite aqueous solution onto the surface of a zinc substrate, and drying it by heating to obtain a zinc anode modified with a composite interface layer.

6. The preparation method according to claim 5, characterized in that, The concentration of organic salt in the organic-inorganic salt composite aqueous solution is 10–100 mg / mL; And / or, the concentration of inorganic salt in the organic-inorganic salt composite aqueous solution is 10-100 mg / mL; And / or, the areal capacity of the organic-inorganic salt composite aqueous solution coating is 10-100 μL cm⁻¹. -2 .

7. The preparation method according to claim 5, characterized in that, The zinc substrate is a pretreated zinc sheet, and the pretreatment includes grinding and impurity removal. And / or, the drying temperature is 40-80℃; And / or, the drying time is 0.5 to 2 hours.

8. The use of a zinc anode modified with a composite interface layer as described in any one of claims 3 or 4 as an anode in an aqueous zinc-ion battery.

9. An aqueous zinc-ion battery, characterized in that, The zinc anode, cathode, separator, and electrolyte are modified with the composite interface layer as described in any one of claims 3 or 4.

10. The aqueous zinc-ion battery according to claim 9, characterized in that, The positive electrode is selected from any one or more of manganese-based oxides, vanadium-based oxides, and Prussian blue. And / or, the diaphragm is made of glass fiber; And / or, the electrolyte comprises an aqueous solution of zinc salt.

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