Graphite paper-based zinc negative electrode and preparation method and application thereof

Abstract

The invention relates to a graphite paper-based zinc negative electrode and a preparation method and application thereof, and belongs to the technical field of novel battery energy storage. The preparation method of the graphite paper-based zinc negative electrode comprises the following steps: by taking graphite paper as a negative electrode, a zinc foil as a positive electrode and a zinc salt aqueous solution as an electrolyte, carrying out electro-deposition by applying constant current, so that zinc ions are subjected to reduction reaction on the surface of the graphite paper to form a zinc deposition layer, and the graphite paper-based zinc negative electrode is obtained. The graphite paper substrate and a hexagonal crystal system of zinc have good lattice matching performance, and zinc can be induced to preferentially deposit along the (002) crystal face. The Zn (002) crystal face has higher electrochemical stability and lower interface energy, and dendritic crystal growth and side reaction are effectively inhibited. Compared with a traditional copper foil substrate, the surface of a zinc deposition layer of the graphite paper substrate is uniform and compact, is rich in metallic luster and has no obvious dendritic crystal protrusions.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of new battery energy storage, and particularly relates to a graphite paper-based zinc negative electrode and a preparation method and application thereof. BACKGROUND

[0002] As a new generation of electrochemical energy storage system, aqueous zinc-ion batteries have shown important application prospects in large-scale energy storage due to their high safety, low cost and environmental friendliness. In order to realize the industrial application of zinc-ion batteries, the lightweight design of the zinc negative electrode becomes a key point. The use of thinner zinc foils (such as 10 μm) can reduce the amount of active material, making the laboratory battery lighter, thereby helping zinc-ion batteries face a wider range of application scenarios. However, this strategy faces severe challenges. Compared with traditional thick zinc negative electrodes, thin zinc negative electrodes are more prone to uneven ion flow during the cycling process, leading to the deterioration of zinc deposition / stripping reversibility, inducing the disorderly growth of dendrites and accelerating the failure of the battery. This change in electrode structure not only causes rapid capacity decay, but also may cause internal short circuit and other safety hazards, which seriously restricts the practical application of thin zinc negative electrodes.

[0003] In view of the technical bottleneck of the zinc negative electrode, current research mainly focuses on electrolyte component regulation, interface modification and three-dimensional electrode structure design. Although these strategies have achieved certain results in inhibiting dendrite growth, the regulation of compact zinc deposition behavior and the improvement of long cycle stability still face great challenges. As an important carrier of electrode reaction, the essential characteristics of the current collector have a decisive influence on the zinc deposition kinetics. The widely used stainless steel and titanium current collector, although has excellent corrosion resistance, is limited by high cost and low conductivity. Therefore, developing a new type of substrate material with good interface compatibility, high conductivity, low cost and effective regulation of zinc deposition behavior is of great significance for improving the performance of zinc negative electrode and promoting the industrialization of zinc-ion batteries. SUMMARY

[0004] The first object of the present application is to provide a graphite paper-based zinc negative electrode, which can regulate the crystal face orientation of zinc deposition when used in a zinc battery, realize uniform zinc deposition and stripping, and improve the cycle life and safety of the zinc battery.

[0005] The second object of the present application is to provide a preparation method of the graphite paper-based zinc negative electrode.

[0006] The third object of the present application is to provide an application of the graphite paper-based zinc negative electrode.

[0007] In order to achieve the above objects, the technical scheme adopted by the present application is as follows:

[0008] A preparation method of a graphite paper-based zinc negative electrode, comprising the following steps: taking graphite paper as a cathode, taking zinc foil as an anode, and taking zinc salt aqueous solution as an electrolyte, and then performing electrodeposition by applying a constant current, so that zinc ions are reduced on the surface of the graphite paper to form a zinc deposition layer, thereby obtaining the graphite paper-based zinc negative electrode.

[0009] Further, the thickness of the graphite paper is 24-25 mu m, and the zinc deposition layer is formed on one side or both sides of the graphite paper.

[0010] Further, the zinc deposition layer is mainly oriented to the Zn (002) crystal face.

[0011] Further, the current density of the constant current is 19-20 mA / cm 2 , the electrodeposition time is 24-25 min, and the surface capacity of the zinc deposition layer during the electrodeposition process is 8.05±0.1 mAh / cm 2 .

[0012] Further, the zinc salt aqueous solution is a zinc sulfate solution with a concentration of 1-2 mol / L.

[0013] Further, before the zinc deposition layer is deposited on the graphite paper, the graphite paper needs to be pretreated, and the pretreatment steps are to sequentially clean with ethanol and water, and then dry.

[0014] A graphite paper-based zinc negative electrode is prepared by using the above-mentioned preparation method of the graphite paper-based zinc negative electrode.

[0015] A graphite paper-based zinc negative electrode in a zinc ion battery.

[0016] Further, the zinc ion battery is a zinc-zinc symmetric battery, a zinc-iodine full battery or a zinc-iodine soft pack battery.

[0017] Further, the zinc-iodine full battery and the zinc-iodine soft pack battery take iodine anodes as anodes, and the preparation method of the iodine anode is as follows: uniformly mixing active carbon, acetylene black and a binder, adding ethanol to form a paste-like substance; rolling and drying the paste-like substance, and then pressing it onto a titanium mesh current collector to obtain a composite carbon material anode sheet; loading iodine on the composite carbon material anode sheet by using an electrochemical deposition method, and then washing and drying to obtain the iodine anode.

[0018] The beneficial effects of the present application are as follows:

[0019] First, the orientation of zinc deposition is regulated. The graphite paper substrate has good lattice matching with the hexagonal system of zinc, which can induce zinc to preferentially deposit along the (002) crystal plane. The Zn(002) crystal plane has higher electrochemical stability and lower interface energy, effectively inhibiting dendrite growth and side reactions. Compared with traditional copper foil substrates, the zinc deposition layer on the graphite paper substrate is uniform, dense and more metallic, with no obvious dendrite protrusions.

[0020] Second, the electrochemical performance of zinc batteries is improved. Under two test conditions of current density of 10 mA / cm 2 and surface capacity of 2 mAh / cm 2 , 5 mAh / cm 2 , the cycle life of the assembled zinc-zinc symmetric battery far exceeds that of ordinary copper foil substrate and pure Zn foil. The assembled zinc-iodine full cell shows superior cycle stability, with a capacity retention rate of 75.1% after 10,000 cycles at a 10C rate. The large-size zinc-iodine single-layer soft-pack battery assembled shows a capacity retention rate of 81.2% of the original capacity after 800 cycles at a current of 0.8 A. The assembled zinc-iodine multi-layer soft-pack battery can provide Ah-level capacity (1.67 Ah) and good cycle stability, with a capacity retention rate of about 60% after 300 cycles at a current of 1 A, and the overall coulombic efficiency is maintained at more than 98%. The stable operation under such high load conditions shows that the graphite paper-based zinc anode of the application has high reliability in handling large currents and high load environments, and can effectively address challenges such as zinc dendrite growth, volume expansion and side reactions.

[0021] Third, it has the advantages of low cost and large-scale production. The graphite paper material used in the application has low cost and abundant reserves, and the preparation process is relatively simple compared to traditional copper foil. It avoids the impact of copper resource price fluctuations and is conducive to large-scale production. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 Figure 1 is a diagram of a separator-free electrochemical deposition device for preparing a graphite paper-based zinc anode;

[0023] Figure 2 Figure 3 is a zinc SEM image and optical photograph of the zinc anode of Example 1 and Comparative Example 1, wherein a is Example 1 and b is Comparative Example 1;

[0024] Figure 3 Figure 4 is a cross-sectional SEM image of the zinc anode of Example 1 and Comparative Example 1, wherein a is Comparative Example 1 and b is Example 1;

[0025] Figure 4 Figure 5 is an XRD pattern of the zinc anode of Example 1 and Comparative Example 1;

[0026] Figure 5In-situ optical microscope observation images and hydrogen production test images of zinc deposition / stripping of zinc anodes in Example 1 and Comparative Example 1, wherein a is the in-situ optical microscope observation image of zinc deposition / stripping of the zinc anode of Comparative Example 1, b is the in-situ optical microscope observation image of zinc deposition / stripping of the zinc anode of Example 1, and c is the hydrogen production test image;

[0027] Figure 6 Long cycle test curves of zinc-zinc symmetric batteries of Example 2, Comparative Example 2 and Comparative Example 5 at a current density of 10 mA / cm 2 , and an area capacity of 2 mAh / cm 2 , wherein a is Example 2, b is Comparative Example 5, and c is Comparative Example 2;

[0028] Figure 7 Long cycle test curves of zinc-zinc symmetric batteries of Example 2, Comparative Example 2 and Comparative Example 5 at a current density of 10 mA / cm 2 , and an area capacity of 5 mAh / cm 2 , wherein a is Example 2, b is Comparative Example 5, and c is Comparative Example 2;

[0029] Figure 8 SEM images of electrode surfaces after different cycles of zinc-zinc symmetric batteries of Example 2 and Comparative Example 2 at a current density of 10 mA / cm 2 , and an area capacity of 5 mAh / cm 2 , wherein a is Comparative Example 2, and b is Example 2;

[0030] Figure 9 Long cycle test results comparison chart of zinc-iodine full batteries of Example 3, Comparative Example 3 and Comparative Example 6;

[0031] Figure 10 Long cycle test results comparison chart of zinc-iodine soft pack batteries of Example 4 and Comparative Example 4, wherein a is Comparative Example 4, and b is Example 4;

[0032] Figure 11 Optical photograph images of Example 1, Comparative Example 1 and Comparative Example 7, wherein a is Example 1, b is Comparative Example 1, and c is Comparative Example 7. DETAILED DESCRIPTION

[0033] The application will be further described below with reference to the embodiments thereof and the accompanying drawings.

[0034] Example 1

[0035] The preparation method of the graphite paper-based zinc negative electrode of Example 1 is as follows: ZnS04·7H20 is dissolved in ultrapure water to form a ZnS04solution with a concentration of 2 mol / L. A zinc foil is used as an anode, and a high-purity graphite paper with a thickness of 25 μm is used as a cathode. The anode and the cathode are placed in the ZnS04solution to construct a diaphragm-free electrochemical deposition device. The constructed diaphragm-free electrochemical deposition device is as shown in Figure 1 A constant current of 20 mA / cm 2 is applied in the electrochemical deposition device to perform electrodeposition. Under the driving of the electric field, zinc ions are stripped from the surface of the zinc foil and migrate to the surface of the cathode substrate through the electrolyte to undergo a reduction reaction, and finally a zinc deposition layer is formed on the surface of the graphite paper. The deposition time is 24 min, and the surface capacity of the zinc deposition layer is 8.05 ± 0.1 mAh / cm 2 , which is equivalent to 10 μm of zinc foil. After the electrodeposition is completed, the graphite paper-based zinc negative electrode is taken out, the surface is washed with ultrapure water for 3 times to remove the residual electrolyte, and then it is naturally dried at room temperature to obtain a single-sided deposited graphite paper-based zinc negative electrode.

[0036] As can be seen from Figure 2 a, on the surface of the graphite paper substrate, zinc grows in a lamellar structure parallel to the substrate, corresponding to the preferred orientation of the Zn(002) crystal plane. At the same time, the zinc deposition layer formed on the surface of the graphite paper substrate presents a relatively bright metal luster, indicating that it has high crystallinity and a dense structure, which is better than that of Comparative Example 1. Figure 3 In the SEM image of Figure 3 b, it can be seen that the interface of the zinc layer in the graphite paper-based zinc negative electrode is flat and its structure is more ordered. Compared with Figure 4 a, there is no obvious protrusion, and a clear and uniform contact interface is formed between the zinc layer and the graphite layer, indicating that the interface is well combined, which helps to reduce the interface resistance and the interface side reaction. As can be seen from , the peak intensity of the Zn(002) crystal plane of the graphite paper-based negative electrode material is much higher than that of the other two materials, indicating that it has a significant deposition tendency of Zn(002) preferred orientation. This crystal plane structure helps to form a more dense, flat and stable Zn deposition layer.

[0037] Under the test conditions of a current density of 10 mA / cm 2 and an area capacity of 5 mAh / cm 2 , the in-situ optical microscope combined with the electrochemical differential mass spectrometer technology is used to perform real-time observation on the internal gas production of the symmetrical battery running for 1 h. As shown in Figure 5 b, no obvious dendrites and bubbles appear in the graphite paper-based zinc negative electrode during the entire deposition process, and only a small amount of bubbles appear in the stripping period after 30 min. At the same time, as can be seen from the hydrogen production rate graph of Figure 5 c, the graphite paper-based zinc negative electrode shows a low and stable hydrogen release rate, indicating that it effectively inhibits the adverse side reaction between zinc and water.

[0038] Example 2

[0039] Application of graphite paper-based zinc anode in zinc-zinc symmetric battery

[0040] The graphite paper-based zinc anode of Example 1 was cut into a circular sheet with a diameter of 12 mm and an area of 1.13 cm 2 . The cut graphite paper-based zinc anode was assembled into a CR2025 type symmetric battery for cycle stability test. The diameter of the battery was 20.0 mm and the thickness was 2.5 mm. The components of the zinc-zinc symmetric battery were in turn anode shell, graphite paper-based zinc anode, separator, graphite paper-based zinc anode, stainless steel gasket, and cathode shell, and the sealing pressure was 50 kg per cubic centimeter. The battery needed to be placed at room temperature for not less than 2 hours before use. The electrolyte used was 2 mol / L zinc sulfate solution, and the amount was 100 μL, which was added after the separator was placed. The diameter of the stainless steel gasket was 16 mm and the thickness was 1 mm. The separator was glass fiber produced by Whatman Company, with a diameter of 110 mm and a thickness of 260 μm, and was cut into a circular sheet with a diameter of 19 mm for use.

[0041] The battery test used the battery test system of Wuhan Lan Electric, and was carried out in a constant temperature box (25°C) to eliminate the influence of environmental temperature. As shown in Figure 6 a, the test parameters were set to constant current discharge and constant current charge, the current density based on the electrode area was 10 mA / cm 2 , and the area capacity was 2 mAh / cm 2 . Under this test condition, the service life of the symmetric battery using the graphite paper-based zinc anode could reach more than 750 hours. When the test condition was changed to a current density of 10 mA / cm 2 and an area capacity of 5 mAh / cm 2 , as shown in Figure 7 a, the zinc-zinc symmetric battery of Example 2 could still be stably operated for more than 190 hours, far exceeding the 46 hours of Comparative Example 2 and the 82 hours of Comparative Example 5. This fully embodies that the graphite paper-based zinc anode can significantly improve the electrochemical performance of the zinc-zinc symmetric battery and significantly improve the cycle life.

[0042] The morphological evolution of the graphite paper-based zinc anode symmetric battery after 2, 25, and 50 cycles under the condition of a current density of 10 mA / cm 2 and an area capacity of 5 mAh / cm 2 was characterized by scanning electron microscopy. As shown in Figure 8 b, Figure 8The upper row in b is the reaction zinc substrate, and the lower row is the deposition morphology on the separator. Compared with Comparative Example 2, the graphite paper-based zinc negative electrode still maintains a flat and uniform Zn deposition morphology even after 50 cycles, and the deposition on the separator is more regular, indicating that it has excellent structural stability and interface control ability.

[0043] Example 3

[0044] Application of graphite paper-based zinc negative electrode in zinc-iodine full cell

[0045] Preparation of iodine positive electrode: active carbon, acetylene black and polytetrafluoroethylene were mixed uniformly according to a mass ratio of 8:1:1, and ethanol was added for stirring to form a paste; then the paste was processed by rolling to form a film, and after drying at room temperature, the film was pressed onto a titanium mesh current collector to obtain a composite carbon material positive electrode sheet. Then the composite carbon material positive electrode sheet and the zinc metal negative electrode sheet were inserted into a 0.5 mol / L zinc iodide aqueous solution, the composite carbon material positive electrode sheet was connected to the positive electrode of the power supply, and the zinc metal negative electrode sheet was connected to the negative electrode of the power supply. A constant current of 1000 mA was applied to the power supply, and iodine was loaded onto the composite carbon material positive electrode sheet by electrodeposition for 18 minutes. The composite carbon material after electrodeposition was surface cleaned with ultrapure water to remove surface residual zinc iodide impurities, and the rinsed material was dried at room temperature to obtain an iodine positive electrode sheet. The iodine positive electrode sheet was cut into a circular sheet with a diameter of 11 mm and an area of 0.949 cm 2 2 .

[0046] The graphite paper-based zinc negative electrode of Example 1 was assembled into a CR2025 type full cell for cycle stability testing. The diameter of the battery was 20.0 mm, and the thickness was 2.5 mm. The assembly sequence of the zinc-iodine full cell was positive electrode shell, iodine positive electrode sheet, separator, graphite paper-based zinc negative electrode, stainless steel gasket, and negative electrode shell. The sealing pressure was 50 kilograms per cubic centimeter. The battery needed to be left to stand for 2 hours at room temperature before use. The electrolyte was a 2 mol / L zinc sulfate solution, and the amount used was 100 μL, which was added after the separator was placed. The thickness of the stainless steel gasket was 1 mm, the separator was glass fiber produced by Whatman Company, and the diameter was 110 mm, which was cut into a circular sheet with a diameter of 19 mm.

[0047] The full cell test was performed using a battery test system from Wuhan Lanbatt and in a constant temperature box (25°C). The test results are shown in Figure 9 Example 3, and Comparative Example 6, showing excellent long-term cycle performance.

[0048] ​Example 4

[0049] Application of graphite paper-based zinc anode in zinc-iodine pouch cells

[0050] Preparation of the iodine cathode: Activated carbon, acetylene black, and polytetrafluoroethylene were mixed uniformly in a mass ratio of 8:1:1, and ethanol was added and stirred to form a paste. This paste was then rolled to form a film, dried at room temperature, and pressed onto a titanium mesh current collector to obtain a composite carbon cathode sheet. Next, the composite carbon cathode sheet and a zinc metal anode sheet were immersed in a 0.5 mol / L zinc iodide aqueous solution. The composite carbon cathode sheet was connected to the positive terminal of a power supply, and the zinc metal anode sheet was connected to the negative terminal. A constant current of 2000 mA was applied to the power supply for 18 minutes to load iodine onto the composite carbon cathode sheet. After electrodeposition, the composite carbon material was surface-cleaned with ultrapure water to remove residual zinc iodide impurities. The rinsed material was dried at room temperature to obtain the final iodine cathode sheet. The iodine cathode sheet was cut into 8×9 cm pieces and weighed for later use. The iodine loading of the active material in the full-cell iodine cathode sheet was approximately 2925 mg.

[0051] The assembly sequence of the zinc-iodine pouch battery is as follows: assemble the graphite paper-based zinc negative electrode, separator, and iodine positive electrode sheet as in Example 1. The assembly of the multilayer pouch battery follows the same procedure, and the batteries are sealed using a vacuum heat sealer. The batteries need to be left to stand at room temperature for 2 hours before use. The separator is made of glass fiber (manufactured by Oral-Glass, cut to 10×10cm). The electrolyte is a 2mol / L zinc sulfate solution; 7mL of electrolyte is added dropwise after the separator is placed in the solution.

[0052] The zinc-iodine pouch batteries were tested in a constant temperature chamber (25℃) to eliminate the influence of ambient temperature. The battery testing used a battery testing system from Wuhan Landian. Figure 10 The assembled single-layer pouch cell can retain 81.16% of its capacity after 800 cycles at 0.8A current, and exhibits a stable discharge capacity curve and extremely high coulombic efficiency. Figure 10 b demonstrates that the assembled multilayer pouch cell can provide Ah-level capacity (1.67Ah) and good cycle stability. Even after 100 cycles under 1A conditions, the capacity retention rate is about 89.9%, and the overall coulombic efficiency is maintained above 98%.

[0053] Comparative Example 1

[0054] ZnSO4·7H2O was dissolved in ultrapure water to form a 2 mol / L ZnSO4 solution. A 9 μm thick copper foil was used as the cathode, and a zinc foil as the anode. The anode and cathode were placed in the ZnSO4 solution to construct a diaphragm-free electrochemical deposition device. A 20 mA / cm² pressure was applied to the electrochemical deposition device. 2Electrodeposition was performed using a constant current. Under the drive of an electric field, zinc ions were stripped from the zinc foil surface and migrated through the electrolyte to the cathode substrate surface, where they underwent a reduction reaction, ultimately forming a zinc deposition layer on the copper foil surface. The deposition time was 24 min, and the areal capacity of the zinc deposition layer was 8.05 ± 0.1 mAh / cm³. 2 This is equivalent to a 10μm zinc foil. After electrodeposition, the copper foil-based zinc anode is removed, rinsed three times with ultrapure water to remove residual electrolyte, and then allowed to air dry at room temperature to obtain a single-sided deposited copper foil-based zinc anode.

[0055] The surface morphology was observed using a Zeiss focused dual-ion beam scanning electron microscope (SEM), such as... Figure 2 As shown in b, a Zn(101) oriented deposition layer is mainly formed on the surface of the zinc anode on the traditional copper foil substrate. Its prismatic grain boundaries easily become initiation sites for dendrite growth. Simultaneously, the zinc deposition layer on the copper foil substrate exhibits a relatively dull grayish-white characteristic. Further cross-sectional SEM images reveal numerous "peak" structures and byproduct formation in the zinc layer on the copper foil surface, indicating uneven zinc deposition on this substrate. This leads to enhanced local electric fields, inducing dendrite growth. XRD further confirms that on the copper foil substrate surface, zinc is mainly concentrated in the Zn(101) crystal plane.

[0056] In addition, in-situ optical microscopy coupled with electrochemical differential mass spectrometry was used at a current density of 10 mA / cm². 2 The surface area capacity is 5mAh / cm². 2 Under the test conditions, the gas production inside the symmetrical battery was observed in real time after running for 1 hour. For example... Figure 5 As shown in Figure a, after prolonged zinc deposition and stripping, a large number of bubbles appeared, and simultaneously... Figure 5 In the hydrogen production rate graph, the amount of hydrogen evolution on the copper foil substrate increases significantly, indicating severe side reactions.

[0057] Comparative Example 2

[0058] Application of copper foil-based zinc anode in zinc-zinc symmetric cells

[0059] The zinc negative electrode on the copper foil substrate of Comparative Example 1 was cut into pieces with a diameter of 12 mm and an area of ​​approximately 1.13 cm². 2 The circular wafers were used to assemble a CR2025 model symmetrical battery with a copper foil substrate and a zinc anode, and then the battery was subjected to cycle stability testing. The battery assembly method was the same as in Example 2.

[0060] The long-cycle testing of the symmetrical batteries was conducted in a constant-temperature chamber maintained at 25°C to eliminate the influence of ambient temperature. The battery testing used was a battery testing system from Wuhan Landian. Figure 6 c. The test parameters are set to constant current discharge and constant current charge, with a current density of 10 mA / cm² based on the electrode area.2 The surface area capacity is 2mAh / cm². 2 Under these test conditions, the symmetrical cell lifespan using a copper foil-based zinc anode is approximately 340 hours, indicating a shorter lifespan. The test conditions were then changed to a current density of 10 mA / cm². 2 The surface area capacity is 5mAh / cm². 2 At times, such as Figure 7 c indicates that the lifespan of a symmetrical battery is only 46 hours.

[0061] SEM was used to study the symmetric cells with zinc anodes on copper foil substrates at a current density of 10 mA / cm². 2 The surface capacity is 5mAh / cm². 2 The morphological evolution after 2, 25, and 50 cycles under certain conditions was observed. For example... Figure 8 As shown in a, Figure 8 The top row in diagram 'a' shows the zinc substrate of the reaction, and the bottom row shows the deposition morphology on the separator. With increasing cycle count, the Zn deposition on the negative electrode surface becomes increasingly uneven. After 50 cycles, numerous obvious Zn dendrite structures appear, and dendrite protrusions and the accumulation of "dead zinc" corrosion products are observed on the separator. This hinders charge transfer and destroys Zn. 2+ Uniform diffusion. During long-term cycling, dendrites tend to preferentially grow vertically in regions with uneven electric fields, posing a risk of piercing the diaphragm and causing a short circuit.

[0062] Comparative Example 3

[0063] Application of copper foil-based zinc anode in zinc-iodine full cells

[0064] A CR2025 full cell was assembled from a copper foil-based zinc anode and an iodine cathode and subjected to cycle stability testing. The assembly sequence of the battery in Comparative Example 3 was the same as that in Example 3. The preparation method of the iodine cathode was the same as that in Example 3.

[0065] Zinc-iodine full cell testing was conducted in a constant temperature chamber (25℃) to eliminate the influence of ambient temperature. The battery testing used a battery testing system from Wuhan Landian, and the test results are as follows: Figure 9 As shown, during charge-discharge testing at a 10C rate, the assembled copper foil-based zinc anode full cell exhibited significant capacity decay after 3000 cycles and began to show overcharge at 5000 cycles. This indicates that the anode material has poor electrochemical stability and is difficult to withstand high-rate charge-discharge conditions.

[0066] Comparative Example 4

[0067] Application of copper foil-based zinc anode in zinc-iodine pouch cells

[0068] The zinc anode from Comparative Example 1, cut into 8.5 × 9.5 cm electrode sheets, was assembled with an 8 × 9 cm iodine cathode sheet to form a pouch cell for cycle stability testing. The preparation method of the iodine cathode was the same as that in Example 4, and the assembly method of the zinc-iodine pouch cell was the same as that in Example 4.

[0069] Zinc-iodine pouch battery testing was conducted in a constant temperature chamber (25℃) to eliminate the influence of ambient temperature. The battery testing system from Wuhan Landian was used. The zinc-iodine single-layer pouch was tested under a constant current charge-discharge condition of 0.8A, and the test results are as follows: Figure 10 As shown in Figure a, overshoot occurs after 400 cycles, and the discharge capacity decays rapidly.

[0070] Comparative Example 5

[0071] Zinc-zinc symmetric cells were assembled using 10μm zinc foil.

[0072] The 10μm zinc foil negative electrode was shaped using an electrode slicer to form a diameter of 12mm and an area of ​​approximately 1.13cm². 2 The discs were used as electrodes. The assembly sequence of the zinc-zinc symmetric battery in Comparative Example 5 was the same as that in Example 2. Long-cycle testing of the zinc-zinc symmetric battery was conducted in a constant temperature chamber maintained at 25°C to eliminate the influence of ambient temperature. The battery testing used a battery testing system from Wuhan Landian. Figure 6 As shown in b, the test parameters were set to constant current discharge and constant current charge, with a current density of 10 mA / cm² based on the electrode area. 2 The surface area capacity is 2mAh / cm². 2 Under these test conditions, the symmetrical cell lifespan using a 10μm zinc foil negative electrode is approximately 380 hours. When the test conditions are changed to a current density of 10 mA / cm²... 2 The surface area capacity is 5mAh / cm². 2 At times, such as Figure 7 b indicates that the symmetrical battery life is 82 hours.

[0073] Comparative Example 6

[0074] Zinc-iodine full cells were assembled using 10μm zinc foil.

[0075] The 10μm zinc foil negative electrode was shaped using an electrode slicer to form a diameter of 12mm and an area of ​​approximately 1.13cm². 2 The discs were used as electrodes. The assembly sequence of the zinc-iodine full cell in Comparative Example 6 was the same as that in Example 3. The zinc-iodine full cell tests were conducted in a constant temperature chamber (25°C) to eliminate the influence of ambient temperature. The battery tests used a battery testing system from Wuhan Landian, and the test results are as follows: Figure 9 As shown. Charge-discharge tests were conducted at a 10C rate, and... Figure 9As can be seen, the assembled 10μm zinc foil anode full cell exhibits rapid capacity decay, with capacity starting to decay rapidly and fail only after 3000 cycles.

[0076] Comparative Example 7

[0077] The preparation method of the zinc anode of Comparative Example 7 is roughly the same as that of Example 1. The difference between the preparation method of the zinc anode of Comparative Example 7 and Example 1 is that the deposition substrate used in Comparative Example 7 is carbon felt.

[0078] from Figure 11 It can be seen that the surface state of zinc deposition on the graphite paper substrate is that the deposition layer is dense and uniform with clear edges and no obvious edge effect. On the carbon felt substrate, the boundary of the deposition area is blurred, the zinc layer is severely unevenly distributed, and there is even obvious accumulation in some areas. This is because carbon felt usually has high porosity and large surface roughness. Its three-dimensional disordered structure easily causes drastic fluctuations in electrolyte distribution and current density at the microscale. This non-uniform electric field environment will induce zinc ions to preferentially nucleate and grow at some positions, resulting in the accumulation of zinc deposition layer clusters with varying thicknesses, which in turn leads to poor electrode contact and increased side reactions, affecting the cycle stability of the battery. In contrast, the surface of graphite paper is flat and dense, with a highly layered structure and good conductivity. During the electrochemical deposition process, it can uniformly guide the directional migration and orderly deposition of zinc ions, thereby forming a dense metal layer with highly preferential orientation along the (002) crystal plane. In addition, graphite paper has excellent flexibility and processability, making it suitable for preparing large-area, highly uniform electrodes, and has good adaptability and scalability for the future industrialization path of zinc batteries. Carbon felt is inherently unfavorable for the stable deposition of zinc layers and induces electrochemical instability, while graphite paper as a substrate has significant advantages in terms of interface morphology control and process compatibility, thus verifying the scientific nature and advancement of this invention in the selection of anode materials.

[0079] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This disclosure is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the claims.

[0080] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. The scope of patent protection of the present invention shall be determined by the claims. Similarly, any equivalent structural changes made based on the content of the present invention's specification shall also be included within the scope of protection of the present invention.

Claims

1. A method for preparing a graphite paper-based zinc negative electrode, characterized by, The method comprises the following steps: The graphite paper-based zinc negative electrode is prepared by applying a constant current to deposit zinc ions on the surface of the graphite paper to form a zinc deposition layer.

2. The method of claim 1, wherein the graphite paper-based zinc negative electrode is prepared by the steps of: (a) preparing a graphite paper; (b) coating the graphite paper with a zinc layer; and (c) coating the zinc layer with a zinc oxide layer. The thickness of the graphite paper is 24-25 μm, and the zinc deposition layer is formed on one side or both sides of the graphite paper.

3. The method for preparing the graphite paper-based zinc anode according to claim 1, characterized in that, The zinc deposition layer is mainly oriented to Zn(002) crystal face.

4. The method for preparing the graphite paper-based zinc anode according to claim 1, characterized in that, The current density of the constant current is 19-20 mA / cm 2 , the time of electrodeposition is 24-25 min; the surface capacity of the zinc deposition layer during the electrodeposition process is 8.05±0.1 mAh / cm 2 .

5. The method for preparing the graphite paper-based zinc anode according to claim 1, characterized in that, The zinc salt aqueous solution is a zinc sulfate solution with a concentration of 1-2 mol / L.

6. The method for preparing the graphite paper-based zinc anode according to claim 1, characterized in that, Before depositing the zinc deposition layer on the graphite paper, the graphite paper needs to be pretreated by sequentially cleaning with ethanol and water and then drying.

7. A graphite paper-based zinc anode, characterized by, The graphite paper-based zinc negative electrode is prepared by the method according to any one of claims 1-6.

8. Application of the graphite paper-based zinc negative electrode according to claim 7 in a zinc ion battery.

9. Use of the graphite paper-based zinc negative electrode according to claim 8, characterized in that, The zinc ion battery is a zinc-zinc symmetric battery, a zinc-iodine full battery or a zinc-iodine soft pack battery.

10. The use of the graphite paper-based zinc negative electrode according to claim 9, characterized in that, The zinc-iodine full battery and the zinc-iodine soft pack battery use iodine as the positive electrode, and the preparation method of the iodine positive electrode is as follows: active carbon, acetylene black and a binder are uniformly mixed, and then ethanol is added to form a paste; the paste is rolled and dried, and then pressed onto a titanium mesh current collector to obtain a composite carbon material positive electrode sheet; iodine is loaded on the composite carbon material positive electrode sheet by electrochemical deposition, and then washed and dried to obtain the iodine positive electrode.

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