Inorganic-organic mixed acid etched zinc negative electrode material and preparation method and application thereof

Abstract

The invention discloses an inorganic-organic mixed acid etched zinc negative electrode material and a preparation method and application thereof, and belongs to the technical field of aqueous zinc ion batteries. The invention aims to solve the problem that the service life of the battery is shortened due to zinc dendrite growth, corrosion and hydrogen evolution in the practical application of the current aqueous zinc ion battery. The mixed acid of hydrochloric acid and citric acid is used for etching commercial zinc foil to obtain the zinc negative electrode etched by inorganic / organic mixed acid, the zinc negative electrode is applied to the aqueous zinc ion battery negative electrode, the three-dimensional structure of the zinc negative electrode can uniformly distribute an electric field, and the high specific surface area can reduce the local current density, so that zinc ions are more uniformly distributed in the deposition / stripping process; and dendritic crystal formation is reduced. And meanwhile, a zinc citrate layer rich in zinc binding sites is generated on the surface in situ, so that the nucleation barrier of zinc ions can be reduced, uniform nucleation is promoted, and under the dual action of the three-dimensional structure and the zinc-loving layer, the generation of zinc dendrites is further inhibited, and the electrochemical performance of the zinc ion battery is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of aqueous zinc ion batteries, and in particular to an inorganic-organic mixed acid-etched zinc negative electrode material, a preparation method thereof, and applications thereof. Background Art

[0002] With the rapid development of society, traditional energy plays a decisive role. Currently, lithium-ion batteries (LIBs) occupy the dominant position in commercial batteries and have broad application prospects in mobile electronic devices, electric vehicles and large-scale grid energy storage systems. However, lithium-ion batteries have obvious disadvantages. The lack of lithium metal resources and its potential safety issues have seriously hindered its further application. Aqueous zinc-ion batteries (ZIBs) are secondary batteries with great development potential due to their inherent safety and low cost. However, commercial zinc foil, as the zinc negative electrode, is affected by the uneven distribution of the electric field during the battery charging and discharging process, resulting in uneven zinc ion deposition, leading to problems such as the growth of zinc phyllites, which directly affects the battery's service life and is the fundamental reason why aqueous zinc-ion batteries are difficult to commercialize.

[0003] To address the aforementioned technical challenges of zinc anodes, the research community has proposed a variety of innovative solutions, primarily including electrode / electrolyte interface engineering, substrate structure optimization, electrolyte composition control, and multifunctional coating construction. Structural engineering of zinc anode substrates has attracted considerable attention due to its effective control over metal deposition behavior. This strategy primarily involves constructing three-dimensional zinc anode structures through surface modification processes such as electrochemical etching and wet etching. Existing research has primarily employed organic or inorganic acid etching of zinc foil. While organic acids offer improved operational safety due to their weaker acidity, the characteristic dimensions of the three-dimensional structures they form are insufficient, resulting in zinc-ion batteries typically maintaining cycling stability only at low current densities. In contrast, while inorganic acid etching systems can form significant three-dimensional structures, their strong acidity makes precise control of etching kinetics difficult, and they also present challenges in wastewater disposal. The inherent non-degradability of the etchants, coupled with the potential for leakage during industrial production, not only increases environmental management costs but also severely restricts the scale-up of this technology. Summary of the Invention

[0004] The main purpose of this invention is to provide a zinc anode material etched with an inorganic-organic mixed acid, as well as its preparation method and application. This anode material can effectively suppress problems such as dendrite formation, corrosion, hydrogen evolution, and passivation in aqueous zinc-ion batteries, thereby improving the cycle rate stability and reversibility of aqueous zinc-ion batteries. The present invention features a simple process, significant results, and environmental friendliness, and has great potential for promoting the industrialization and application of aqueous zinc-ion batteries.

[0005] To achieve the above object, the present invention provides a method for preparing a zinc negative electrode material etched by inorganic-organic mixed acid, comprising the following steps:

[0006] A hydrochloric acid aqueous solution and a citric acid aqueous solution are mixed to obtain a mixed acid etching solution; then the pretreated zinc foil is placed in the mixed acid etching solution for ultrasonic etching, the etched zinc foil is taken out and washed with deionized water and ethanol, and then placed in a vacuum drying oven for drying to obtain an inorganic-organic mixed acid etched zinc negative electrode material.

[0007] Preferably, the concentration of the hydrochloric acid aqueous solution is 3-8wt%; the concentration of the citric acid aqueous solution is 10-30wt%; and the volume ratio of the hydrochloric acid aqueous solution to the citric acid aqueous solution is 1-2:1-2.

[0008] Preferably, the pretreatment method of the zinc foil is to polish the surface of the zinc foil with sandpaper, and then wash it with deionized water and ethanol in sequence.

[0009] Preferably, the ultrasonic power is 300-500W.

[0010] Preferably, the etching time is 1-10 minutes.

[0011] Preferably, the etching temperature is 15°C-25°C.

[0012] Preferably, the drying temperature is 60-80° C., and the drying time is 1-3 hours.

[0013] The invention also discloses the inorganic-organic mixed acid-etched zinc negative electrode material prepared by the method for preparing the inorganic-organic mixed acid-etched zinc negative electrode material.

[0014] The invention also discloses the application of the zinc negative electrode material etched by the inorganic-organic mixed acid in an aqueous zinc ion battery.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. The present invention has developed a self-driven redox etching technology based on an inorganic / organic mixed acid system. Under normal temperature and pressure conditions, a hydrochloric acid-citric acid synergistic etching mechanism is used to simultaneously construct a three-dimensional structure on the surface of the zinc substrate and in situ construct a zinc citrate protective layer with zinc ion coordination function, realizing the integration of surface morphology control and interface engineering.

[0017] 2. The zinc negative electrode material synthesized by the present invention has a three-dimensional structure that can uniformly distribute the electric field and reduce the local current density gradient. The high specific surface area feature enables uniform distribution of zinc ions during the electrodeposition / dissolution process, effectively reducing the tip effect caused by electric field concentration, thereby inhibiting the preferential nucleation and growth of dendrites. At the same time, the zinc citrate layer generated in situ on its surface is rich in zinc binding sites, which can reduce the nucleation barrier of zinc ions and promote uniform nucleation. Under the dual effects of the three-dimensional structure and the zinc-philic layer, the formation of zinc dendrites is further inhibited;

[0018] 3. The present invention provides a method for preparing a zinc negative electrode material etched with an inorganic / organic mixed acid. By strictly controlling the mass concentration, volume mixing ratio, and etching time of hydrochloric acid and citric acid in the mixed acid, the morphology of the protective layer is effectively regulated, and a zinc negative electrode material etched with an inorganic / organic mixed acid is successfully prepared, ensuring the controllability of the structural performance of the zinc negative electrode material.

[0019] 4. The present invention provides a method for preparing a zinc negative electrode etched by inorganic / organic mixed acid. The preparation process is simple and easy to operate, and it has good application prospects as a negative electrode material for aqueous zinc ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 This is the SEM image of 2:1 3D-Zn prepared in Example 1 of the present invention;

[0022] Figure 2 This is the SEM image of the conventional commercial zinc foil of Comparative Example 1 of the present invention;

[0023] Figure 3 This is the XRD pattern of 2:1 3D-Zn prepared in Example 1 of the present invention;

[0024] Figure 4 The Zn / / Zn symmetrical battery assembled from Example 1 of the present invention and Comparative Example 1 was tested at 2 mA·cm -2 Current density, 1 mAh cm -2 Time-voltage diagram under deposition capacity;

[0025] Figure 5 The Zn / / Zn symmetrical battery 2 mA·cm assembled in Example 2 of the present invention -2 Current density, 1 mAh cm-2 Time-voltage diagram under deposition capacity;

[0026] Figure 6 The Zn / / Zn symmetrical battery 2 mA·cm assembled in Example 3 of the present invention -2 Current density, 1 mAh cm -2 Time-voltage diagram under deposition capacity;

[0027] Figure 7 The Zn / / Zn symmetrical battery assembled in Comparative Example 2 of the present invention is -2 Current density, 1 mAh cm -2 Time-voltage diagram under deposition capacity;

[0028] Figure 8 The Zn / / Zn symmetrical battery assembled in Comparative Example 3 of the present invention is -2 Current density, 1 mAh cm -2 Time-voltage diagram of the deposition capacity.

[0029] Figure 9 The Zn / / Cu half-cells assembled in Example 1 and Comparative Example 1 were -2 Current density, 1 mAh cm -2 Cycle number versus Coulomb efficiency plot for deposition capacity.

[0030] Figure 10 The Zn / / δ-MnO2 fully symmetrical battery assembled for Example 1 and Comparative Example 1 was -1 Cycling performance diagram at current density of .

[0031] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0032] Unless otherwise specified, the experimental methods involved in the embodiments of the present invention are all conventional methods; the materials, reagents, instruments, equipment, etc. used, unless otherwise specified, can be obtained through commercial channels.

[0033] Hydrochloric acid and citric acid were purchased from commercial sources.

[0034] Zinc foil preparation: Commercially available 100μm thick zinc foil was used as the raw material. The surface was polished with 2500-grit and 5000-grit sandpaper to remove the oxide layer and impurities, and then cleaned with water and anhydrous ethanol. Subsequently, a cutting machine was used to process the treated zinc foil into 12mm diameter discs, which were used in the following battery systems: 1) as positive / negative electrode material for symmetrical half-cells; 2) as negative electrode material for asymmetric half-cells; 3) as negative electrode material for full batteries.

[0035] Preparation of diaphragm: The commercially available GF-D glass fiber diaphragm was punched into discs with a diameter of 19 mm using a cutting machine and stored for later use.

[0036] Copper foil preparation: Commercially available copper foil was punched into discs with a diameter of 16.2 mm and stored for use as the positive electrode material of the asymmetric half-cell.

[0037] δ-MnO2 cathode preparation:

[0038] (1) Preparation of PVDF colloid: polyvinylidene fluoride binder (PVDF) and N-methylpyrrolidone (NMP) were mixed at a mass ratio of 1:19 and stirred thoroughly to dissolve to prepare 5% PVDF colloid;

[0039] (2) Preparation of electrode slurry: δ-MnO2, acetylene black and PVDF binder (calculated by PVDF dry weight) were mixed in a mass ratio of 7:2:1, an appropriate amount of NMP solvent was added, and stirred until a uniform slurry was formed;

[0040] (3) Electrode preparation: The slurry was evenly coated on a 30 μm thick titanium foil using a doctor blade coating method. After vacuum drying at 60 °C for 12 h, it was punched into discs with a diameter of 12 mm. The active material loading was controlled at 0.9-1.4 mg cm -2 The obtained electrode is used as the positive electrode of the whole battery.

[0041] Example 1

[0042] A method for preparing a zinc negative electrode material etched by inorganic-organic mixed acid comprises the following steps:

[0043] 60 mL of 5 wt% hydrochloric acid aqueous solution and 30 mL of 20 wt% citric acid were mixed and stirred to obtain a mixed acid etching solution. The pretreated zinc sheet was vertically immersed in the mixed acid etching solution, then placed in an ultrasonic cleaner and ultrasonically etched for 10 min at 20°C and 400 W. Finally, it was placed in an oven at 60°C and dried for 2 h to obtain an inorganic-organic mixed acid-etched zinc negative electrode material, abbreviated as 2:1 3D-Zn.

[0044] The SEM spectrum of the zinc negative electrode material 2:1 3D-Zn prepared in this example is as follows Figure 1As shown in the figure, a clear three-dimensional structure can be seen. The XRD pattern of the zinc negative electrode material 2:1 3D-Zn is as follows Figure 3 As shown in the figure, it can be seen that the characteristic diffraction peaks of zinc citrate are detected at 2θ=12°, 15°, and 19°, confirming the in situ construction of the surface zinc citrate protective layer. Combined with morphology and phase analysis, this study successfully achieved the simultaneous regulation of the three-dimensional structure design and interface modification of the zinc substrate, and prepared an inorganic / organic mixed acid-etched zinc negative electrode material.

[0045] The 2:1 3D-Zn prepared in this example was cut into 12mm zinc sheets and used as positive and negative electrodes to assemble a CR2032Zn / / Zn symmetrical battery. The assembled CR 2032 symmetrical battery was subjected to charge and discharge experiments on a blue power test system. The experimental results are shown in the figure. Figure 4 As shown in the figure, it can be seen that at a current density of 2 mA cm -2 , deposition capacity is 1 mAh·cm -2 Under the conditions of , the Zn / / Zn symmetrical battery of this embodiment did not short-circuit for 3300h.

[0046] The 2:1@3D-Zn prepared in this example was used as the negative electrode and the 16.2 mm copper foil was used as the positive electrode to assemble a CR 2032 half-cell. The cycle performance test results of the half-cell are shown in Figure 2. Figure 9 As shown in the figure, it can be seen that the half-battery of Example 1 still has a relatively stable coulombic efficiency after 2000 charging cycles.

[0047] A 2:1 3D-Zn with a diameter of 14 mm was used as the negative electrode, a δ-MnO2 with a diameter of 12 mm was used as the positive electrode, and 130 microliters of 2 mol / L ZnSO4 + 0.2 mol / L MnSO4 was selected as the electrolyte to assemble a CR 2023 full battery. The CR2023 full battery assembled in this embodiment was subjected to a 1 A / g charge and discharge test on a blue electric test system. The test results are shown in FIG. Figure 10 As shown, it can be seen that after matching the positive electrode, the initial capacity of the full battery is about 260mAh / g at a current density of 1A / g, and the capacity remains relatively stable after 500 cycles.

[0048] Example 2

[0049] A method for preparing a zinc negative electrode material etched by inorganic-organic mixed acid comprises the following steps:

[0050] 30 mL of 5 wt% hydrochloric acid aqueous solution and 60 mL of 20 wt% citric acid were mixed and stirred evenly to obtain a mixed acid etching solution. The pretreated zinc sheet was vertically immersed in the mixed acid etching solution, then placed in an ultrasonic cleaner and ultrasonically etched for 10 min at 20°C and 400 W. Finally, it was placed in an oven at 60°C and dried for 2 h to obtain an inorganic-organic mixed acid-etched zinc negative electrode material, abbreviated as 1:2 3D-Zn.

[0051] The zinc negative electrode material 1:2 3D-Zn prepared in this example was cut into 12mm zinc sheets, used as positive and negative electrodes, and assembled into a CR 2032Zn / / Zn symmetrical battery. The assembled CR 2032Zn / / Zn symmetrical battery was subjected to charge and discharge experiments on a blue power test system. The test results are shown in the figure. Figure 5 As shown, at a current density of 2 mA·cm -2 , deposition capacity is 1 mAh·cm -2 Under the conditions of , the Zn / / Zn battery assembled in this embodiment short-circuited at approximately 850 h.

[0052] Example 3

[0053] A method for preparing a zinc negative electrode material etched by inorganic-organic mixed acid comprises the following steps:

[0054] 45 mL of 5 wt% hydrochloric acid aqueous solution and 45 mL of 20 wt% citric acid were mixed and stirred to obtain a mixed acid etching solution. The pretreated zinc sheet was vertically immersed in the mixed acid etching solution, and then placed in an ultrasonic cleaner and ultrasonically etched for 10 min at 20°C and 400 W. Finally, it was placed in an oven at 60°C and dried for 2 h to obtain an inorganic-organic mixed acid-etched zinc negative electrode material, abbreviated as 1:1 3D-Zn.

[0055] The zinc negative electrode material 1:1 3D-Zn prepared in this example was cut into 12mm zinc sheets, used as positive and negative electrodes, and assembled into a CR 2032Zn / / Zn symmetrical battery. The assembled CR 2032Zn / / Zn symmetrical battery was subjected to charge and discharge experiments on a blue power test system. The test results are shown in the figure. Figure 6 As shown in the figure, it can be seen that at a current density of 2 mA cm -2 , deposition capacity is 1 mAh·cm -2 Under the conditions of , the CR 2032Zn / / Zn battery assembled in this embodiment short-circuited at approximately 760 h.

[0056] Comparative Example 1

[0057] Pure zinc foil was used as the positive and negative electrodes to assemble a symmetrical battery. The assembled CR 2032 symmetrical battery was subjected to charge and discharge experiments on a blue power test system. The experimental results are as follows: Figure 4As shown in the figure, it can be seen that at a current density of 2 mA cm -2 , deposition capacity is 1 mAh·cm -2 Under the conditions of , the polarization voltage of the symmetrical battery assembled in this comparative example fluctuated greatly during the cycle and a short circuit occurred at about 230h.

[0058] Pure zinc foil was used as the negative electrode and copper foil as the positive electrode to assemble a half-cell. The assembled half-cell was subjected to charge and discharge experiments on a blue-electric test system. The experimental results are as follows: Figure 9 As shown in the figure, it can be seen that at a current density of 4 mA cm -2 , deposition capacity is 1 mAh·cm -2 The half-cell test was carried out under the following conditions. The half-cell of Comparative Example 1 was short-circuited after the charge and discharge cycle reached 400 cycles.

[0059] Pure zinc foil was used as the negative electrode and δ-MnO2 was used as the positive electrode to assemble a full battery. The assembled full battery was subjected to a 1A / g charge and discharge test on a blue electric test system. The test results are as follows: Figure 10 As shown, it can be seen that the capacity retention rate of the full battery is relatively low at a current density of 1 A / g.

[0060] Comparative Example 2

[0061] A method for preparing a zinc negative electrode material, comprising the following steps:

[0062] The pretreated zinc foil was vertically immersed in 90 mL of 5 wt% hydrochloric acid aqueous solution, then ultrasonically etched in an ultrasonic cleaner at 20°C and 400W for 10 minutes, and finally dried in a 60°C oven for 2 hours to obtain an inorganic acid-etched zinc negative electrode material, abbreviated as HCl 3D-Zn. The zinc negative electrode material HCl3D-Zn was then used as the positive and negative electrodes to assemble a symmetrical battery. The assembled CR 2032 symmetrical battery was subjected to charge and discharge experiments on a blue electric test system. The experimental results are shown in FIG. Figure 7 As shown in the figure, it can be seen that at a current density of 2 mA cm -2 , deposition capacity is 1 mAh·cm -2 Under the conditions of , the symmetrical battery assembled in this comparative example suffered a short circuit at approximately 800 h during the cycle.

[0063] Comparative Example 3

[0064] A method for preparing a zinc negative electrode material, comprising the following steps:

[0065] The pretreated zinc foil was vertically immersed in 90 mL of 20 wt% citric acid aqueous solution, then ultrasonically etched in an ultrasonic cleaner at 20 ° C and 400 W for 10 minutes, and finally dried in a 60 ° C oven for 2 hours to obtain an organic acid-etched zinc negative electrode material, abbreviated as CA-Zn; the zinc negative electrode material CA-Zn was then used as the positive and negative electrodes to assemble a symmetrical battery, and the assembled CR2032 symmetrical battery was subjected to charge and discharge experiments on a blue electric test system. The experimental results are shown in FIG. Figure 8 As shown in the figure, it can be seen that at a current density of 2 mA cm -2 , deposition capacity is 1 mAh·cm -2 Under the conditions of , the symmetrical battery assembled in this comparative example suffered a short circuit at approximately 500 h during the cycle.

[0066] The test results of the Zn / / Zn symmetrical batteries obtained in the above examples and comparative examples are summarized in Table 1 below:

[0067] Table 1 Test results of Zn / / Zn symmetrical batteries obtained in Examples and Comparative Examples

[0068]

[0069] The present invention constructs a three-dimensional zinc citrate protective layer on the surface of the zinc negative electrode by a simple ultrasonic etching method. The protective layer has a three-dimensional structure and abundant nucleation sites, which is beneficial to the uniform electric field and promotes the Zn 2+ The uniform deposition of zinc can effectively inhibit the formation of zinc dendrites and can greatly improve the cycle life and stability of aqueous zinc-ion batteries.

[0070] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of the present invention.

Claims

1. A method for preparing a zinc negative electrode material etched by inorganic and organic mixed acid, characterized in that: The steps include: A hydrochloric acid aqueous solution and a citric acid aqueous solution are mixed to obtain a mixed acid etching solution; then the pretreated zinc foil is placed in the mixed acid etching solution for ultrasonic etching, the etched zinc foil is taken out and washed with deionized water and ethanol, and then placed in a vacuum drying oven for drying to obtain an inorganic-organic mixed acid etched zinc negative electrode material.

2. The preparation method according to claim 1, wherein: The concentration of the hydrochloric acid aqueous solution is 3-8 wt %; the concentration of the citric acid aqueous solution is 10-30 wt %.

3. The preparation method according to claim 1, wherein: The volume ratio of the hydrochloric acid aqueous solution to the citric acid aqueous solution is 1-2:1-2.

4. The preparation method according to claim 1, wherein: The pretreatment method of the zinc foil is to polish the surface of the zinc foil with sandpaper, and then wash it with deionized water and ethanol in sequence.

5. The preparation method according to claim 1, wherein: The ultrasonic power is 300-500W.

6. The preparation method according to claim 1, wherein: The etching time is 1-10 minutes.

7. The preparation method according to claim 1, wherein: The etching temperature is 15°C-25°C.

8. The preparation method according to claim 1, wherein: The drying temperature is 60-80° C., and the drying time is 1-3 hours.

9. A zinc negative electrode material etched by an inorganic-organic mixed acid, characterized in that: The compound is prepared by the preparation method according to any one of claims 1 to 8.

10. An application of the zinc negative electrode material etched by inorganic-organic mixed acid according to claim 9, characterized in that: The zinc negative electrode material etched by the inorganic-organic mixed acid is used in an aqueous zinc ion battery.

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