Preparation method of zinc ion battery negative plate

Abstract

The invention discloses a preparation method of a zinc ion battery negative plate. The preparation method comprises the following steps: carrying out surface treatment on a zinc plate; and placing the zinc sheet subjected to surface treatment in a soluble lead salt solution, and continuously reacting for a preset period of time to obtain the zinc negative electrode sheet with the surface covered with a lead layer. According to the preparation method, the lead layer is deposited on the surface of the zinc sheet, and the surface of the zinc sheet is wrapped and covered by the lead layer, so that the battery negative electrode is protected, dendritic crystal growth caused by non-uniform deposition of zinc ions on the negative electrode sheet is avoided, the battery performance and safety are ensured, and the battery efficiency is improved while the internal resistance of the battery is reduced; the zinc sheet is separated from water by covering the lead layer, so that the corrosion of the negative plate is reduced, the influence of corrosion byproducts on the battery performance is avoided, the consumption of the negative plate and the internal resistance of the battery are reduced, and the battery efficiency and the service life of the battery are improved; the surface of the zinc sheet is protected through the lead layer, decomposition of water in the charging and discharging process is inhibited, the problem of battery gas expansion and explosion caused by hydrogen evolution reaction is avoided, the energy density and cycle life of the battery are guaranteed, and normal work of the battery is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and particularly to a method for preparing a negative electrode sheet of a zinc-ion battery. Background Art

[0002] Aqueous zinc-ion batteries are new energy storage devices that utilize zinc aqueous chemical reactions for energy storage and release. During the discharge process of the battery, electrons released during the negative electrode reaction flow in the external circuit and undergo a reduction reaction with an oxidant, causing zinc ions to be generated on the positive electrode; during the charging process, an external power source reversely injects electrons into the battery through the external circuit, causing the reactor raw material zinc ions to be reduced to zinc metal precipitate in an aqueous environment. During the charge and discharge process of the aqueous zinc-ion battery, the deposition of zinc ions on the zinc negative electrode is uneven, forming dendritic metal zinc crystals (dendrites). These dendrites may pierce the separator, resulting in an internal short circuit of the battery, seriously affecting the performance and safety of the battery; at the same time, the growth of dendrites will also make the surface of the battery negative electrode rough, increasing the internal resistance of the battery, thereby reducing the efficiency of the battery. Secondly, water, which is used as an electrolyte solvent inside the battery, will decompose and release hydrogen during the charge and discharge process. The release of hydrogen will cause the battery to swell and may even cause an explosion; moreover, the hydrogen evolution reaction (the process of generating hydrogen) will consume the water in the battery, reducing the energy density and cycle life of the battery; the hydrogen evolution reaction will compete with the zinc electrodeposition process for electrons, thus affecting the normal operation of the battery. In addition, since metallic zinc is relatively active, it will spontaneously react with water chemically, resulting in the continuous consumption of the zinc negative electrode material (negative electrode corrosion reaction). This corrosion reaction will not only reduce the reversible capacity of the battery but also produce insoluble by-products that are difficult to play a protective role, thereby affecting the performance of the battery; the corrosion reaction will also increase the internal resistance of the battery, reducing the efficiency and service life of the battery. Summary of the Invention

[0003] Based on this, in view of the above deficiencies, it is necessary to provide a method for preparing a negative electrode sheet of a zinc-ion battery that can reduce dendrite growth and hydrogen evolution reaction, and protect the battery negative electrode to reduce negative electrode corrosion.

[0004] A method for preparing a negative electrode sheet of a zinc-ion battery includes the following steps:

[0005] S1. Perform surface treatment on the zinc sheet;

[0006] S2. Place the zinc sheet after surface treatment in a soluble lead salt solution and continuously react for a preset duration to obtain a zinc negative electrode sheet with a lead layer on its surface.

[0007] In one embodiment, step S1 includes:

[0008] S11. Cut the zinc material into zinc sheets of a preset size;

[0009] S12. Clean the zinc sheet;

[0010] S13. Immerse the zinc sheet in the acid solution and continue the reaction for a preset time;

[0011] S14. Take out the zinc sheet from the acid solution and clean the zinc sheet.

[0012] In one embodiment, in step S12, the zinc sheet is cleaned with deionized water and ethanol.

[0013] In one embodiment, in step S13, the zinc sheet is immersed in a hydrochloric acid solution, and the soluble lead salt solution is a lead chloride solution.

[0014] In one embodiment, in step S13, the zinc sheet is immersed in a nitric acid solution, and the soluble lead salt solution is a lead nitrate solution.

[0015] In one embodiment, in step S13, the zinc sheet is immersed in an acetic acid solution, and the soluble lead salt solution is a lead acetate solution.

[0016] In one embodiment, the solvent of the soluble lead salt solution is water, or ethylene glycol, or PVDF.

[0017] In one embodiment, the concentration of the soluble lead salt solution is 0.1 - 0.2 mol / L, and the immersion time of the zinc sheet in the soluble lead salt solution is 1 - 10 min.

[0018] In one embodiment, after step S2, it further includes:

[0019] S3. Take out the zinc negative electrode sheet with a lead layer on its surface from the soluble lead salt solution, clean and dry the zinc negative electrode sheet.

[0020] In one embodiment, the thickness of the lead layer is 30 - 50 μm.

[0021] Implementing the preparation method of the zinc ion battery negative electrode sheet of the present invention, a lead layer is deposited on the surface of the zinc sheet, and the surface of the zinc sheet is wrapped and covered by the lead layer to achieve the protection of the battery negative electrode, which can avoid the dendrite growth caused by uneven deposition of zinc ions on the negative electrode sheet, ensure the battery performance and safety, reduce the battery internal resistance while improving the battery efficiency; through the coverage of the lead layer, the zinc sheet can be separated from water, reducing the corrosion of the negative electrode sheet, avoiding the influence of corrosion by-products on the battery performance, further reducing the consumption of the negative electrode sheet and the battery internal resistance, improving the battery efficiency and the battery service life; through the protection of the lead layer on the surface of the zinc sheet, the decomposition of water during charge and discharge can be inhibited, avoiding the problem of battery swelling and explosion caused by the hydrogen evolution reaction, ensuring the energy density and cycle life of the battery, and ensuring the normal operation of the battery. Brief Description of the Drawings

[0022] Figure 1The graph showing the relationship between the capacity and Coulomb efficiency of the aqueous zinc-manganese battery prepared from the negative electrode sheet of the zinc-ion battery and the number of cycles in Example 1 of the present invention;

[0023] Figure 2 The graph showing the relationship between the discharge specific capacity and the number of cycles in Example 1 and Comparative Example 1 of the present invention;

[0024] Figure 3 The graph showing the relationship between the specific capacity and voltage within 120 cycles of the aqueous zinc-manganese battery prepared from the negative electrode sheet of the zinc-ion battery in Example 1 of the present invention;

[0025] Figure 4 The graph showing the relationship between dQ / dV and voltage within 120 cycles of the aqueous zinc-manganese battery prepared from the negative electrode sheet of the zinc-ion battery in Example 1 of the present invention. Detailed implementation manners

[0026] In order to make the above objects, features and advantages of the present invention more obvious and understandable, the following will describe the detailed implementation manners of the present invention with reference to the accompanying drawings. Many specific details are set forth in the following description in order to fully understand the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0027] The present invention discloses a preparation method of a negative electrode sheet of a zinc-ion battery for protecting the negative electrode of the battery, reducing dendrite growth, hydrogen evolution reaction and negative electrode corrosion by depositing a Pb metal layer in a solution. The preparation method includes the following steps:

[0028] S1. Perform surface treatment on the zinc sheet.

[0029] In this embodiment, by performing surface treatment on the zinc sheet, impurities and oxide layers on the surface of the zinc sheet can be removed, so that zinc atoms on the surface of the zinc sheet are exposed, providing a chemical reaction surface on the surface of the zinc sheet and enabling the lead layer to firmly adhere to the surface of the zinc sheet.

[0030] Further, step S1 includes:

[0031] S11. Cut the zinc material into zinc sheets of a preset size. Specifically, cut the zinc material into rectangular zinc sheets with a size of 3.5 cm x 4.5 cm. The length and width dimensions of the rectangular zinc sheets are the length and width dimensions of the finished negative electrode sheet.

[0032] S12. Clean the zinc sheet. In step S12, deionized water and ethanol are used to clean the zinc sheet. Specifically, first use deionized water to clean the dust or particulate impurities on the surface of the zinc sheet; then use ethanol to clean the zinc sheet to dissolve the organic pollutants, bacteria and viruses on the surface of the zinc sheet, and further wash away the impurities remaining on the surface of the zinc sheet to avoid zinc sheet corrosion; finally, use deionized water to clean the zinc sheet again to remove the ethanol remaining on the surface of the zinc sheet. It should be noted that in this embodiment, the zinc sheet can be cleaned by soaking in deionized water and ethanol; it can also be cleaned by combining flowing deionized water with ethanol soaking; it can also pour deionized water and ethanol into an ultrasonic cleaning device, and drive the deionized water or ethanol to vibrate through ultrasonic waves, so that the deionized water and ethanol hit and clean the zinc sheet at high frequency, improving the cleaning efficiency and cleaning effect of the zinc sheet.

[0033] S13. Immerse the zinc sheet in the acid solution and react for a preset time. The acid solution can be one of hydrochloric acid (HCl) solution, nitric acid (HNO 3 ) solution and acetic acid (CH 3 COOH) solution. Further, the concentration of the acid solution is 0.1 mol / L, and the soaking time of the zinc sheet in the acid solution is 2 - 5 min. By immersing the zinc sheet in the acid solution and using the corrosion effect of the acid solution on the zinc sheet, the oxide layer on the surface of the zinc sheet is removed, so that the zinc atoms on the surface of the zinc sheet are exposed, facilitating the subsequent displacement reaction between zinc atoms and lead ions. When the acid solution is HCl solution, zinc oxide (ZnO) on the surface of the zinc sheet reacts with HCl as follows: ZnO + 2HCl → ZnCl 2 +H 2 O, making the zinc oxide produced on the surface of the zinc sheet dissolve in water as ZnCl 2 , so as to remove ZnCl 2 by washing. When the acid solution is HNO 3 solution, zinc oxide (ZnO) on the surface of the zinc sheet reacts with HNO 3 as follows: ZnO + 2HNO 3 →Zn(NO 3 ) 2 +H 2 O, making the zinc oxide produced on the surface of the zinc sheet dissolve in water as Zn(NO 3 ) 2 , so as to remove Zn(NO 3 ) 2 by washing. When the acid solution is CH 3 COOH solution, zinc oxide (ZnO) on the surface of the zinc sheet reacts with CH 3 COOH as follows: ZnO + 2CH 3 COOH→Zn(CH 3 COO) 2 +H2 O such that zinc oxide on the surface of the zinc sheet produces Zn(CH 3 COO) that is soluble in water 2 , so as to remove Zn(CH 3 COO) by washing 2 .

[0034] S14. Take out the zinc sheet from the acid solution and wash the zinc sheet.

[0035] Specifically, take out the pickled zinc sheet from the acid solution and place the zinc sheet under a flowing deionized water stream for rinsing to remove the residual acid solution on the surface of the zinc sheet, so as to avoid the continuous corrosion of the zinc sheet surface by the acid solution, thereby causing the uncontrollable problem of the zinc sheet thickness. In other words, in this embodiment, by controlling the soaking time of the zinc sheet in the acid solution and the acid solution concentration, the thickness of the pickled zinc sheet can be controlled.

[0036] S2. Place the surface-treated zinc sheet in a soluble lead salt solution and react for a preset duration to obtain a zinc negative electrode sheet with a lead layer covering the surface.

[0037] To reduce the influence of residual ions on the surface of the pickled zinc sheet on the reaction between the zinc sheet and the soluble lead salt solution, it is necessary to make the anions in the acid solution the same as the anions in the soluble lead salt. Specifically, in one embodiment, in step S13, the zinc sheet is immersed in a hydrochloric acid (HCl) solution, and the soluble lead salt solution is a lead chloride (PbCl 2 ) solution. When the soluble lead salt solution is a lead chloride (PbCl 2 ) solution, the following reaction occurs after the zinc sheet is placed in the soluble lead salt solution: Zn + PbCl 2 →Pb + ZnCl 2 . After the reaction, a displacement reaction occurs between lead ions and zinc atoms, causing the lead ions to deposit on the surface of the zinc sheet, thereby forming a lead layer that covers and wraps the surface of the zinc sheet to achieve the protection of the zinc sheet. In another embodiment, in step S13, the zinc sheet is immersed in a nitric acid (HNO 3 ) solution, and the soluble lead salt solution is a lead nitrate (Pb(NO 3 ) 2 ) solution. When the soluble lead salt solution is a lead nitrate (Pb(NO 3 ) 2 ) solution, the following reaction occurs after the zinc sheet is placed in the soluble lead salt solution: Zn + Pb(NO 3 ) 2 →Pb + Zn(NO 3 ) 2, after the reaction, a displacement reaction occurs between lead ions and zinc atoms, causing the lead ions to deposit on the surface of the zinc sheet, thereby forming a lead layer that covers and wraps the surface of the zinc sheet to achieve the protection of the zinc sheet. In another embodiment, in step S13, the zinc sheet is immersed in acetic acid (CH 3 COOH) solution, and the soluble lead salt solution is lead acetate (Pb(CH 3 COO) 2 ). When the soluble lead salt solution is lead acetate (Pb(CH 3 COO) 2 ) solution, the following reaction occurs when the zinc sheet is placed in the soluble lead salt solution: Zn + Pb(CH 3 COO) 2 → Pb + Zn(CH 3 COO) 2 . After the reaction, a displacement reaction occurs between lead ions and zinc atoms, causing the lead ions to deposit on the surface of the zinc sheet, thereby forming a lead layer that covers and wraps the surface of the zinc sheet to achieve the protection of the zinc sheet.

[0038] In one embodiment, the concentration of the soluble lead salt solution is 0.1 - 0.2 mol / L, and the immersion time of the zinc sheet in the soluble lead salt solution is 1 - 10 min. Further, the solvent of the soluble lead salt solution is water, or ethylene glycol, or PVDF (polyvinylidene fluoride), that is, the soluble lead salt solution is obtained by dissolving the soluble lead salt in water or ethylene glycol or liquid PVDF. It should be noted that in this embodiment, the reaction temperature of the zinc sheet in the soluble lead salt solution is room temperature (20 - 25 °C) to slow down the reaction rate between zinc atoms and lead ions, so that the lead ions accumulate on the surface of the zinc sheet during the displacement process, thereby generating a dense and uniform lead layer on the surface of the zinc sheet. Preferably, the thickness of the lead layer is 30 - 50 μm.

[0039] Further, after step S2, it further includes:

[0040] S3. Take out the zinc negative electrode sheet with a lead layer on its surface from the soluble lead salt solution, and wash and dry the zinc negative electrode sheet. Specifically, take out the zinc sheet after the displacement reaction from the soluble lead salt solution, wash the zinc sheet thoroughly with deionized water, and then place the washed zinc sheet in an environment of 40 - 60 °C for drying to remove the moisture on the surface of the zinc sheet, thereby obtaining a zinc negative electrode sheet coated with a Pb metal layer.

[0041] The preparation process of the zinc ion battery negative electrode sheet is described below with specific examples.

[0042] Example 1

[0043] First, cut zinc sheets with a size of 3.5×4.5 cm, and thoroughly clean the zinc sheets in the order of deionized water cleaning - ethanol cleaning - deionized water re - cleaning. Subsequently, fully immerse the cleaned zinc sheets in 0.1 mol / L HCl solution to remove the oxide layer on the surface of the zinc sheets through pickling. After soaking for 2 min, take out the zinc sheets and thoroughly clean them with deionized water. Then, fully soak the pickled zinc sheets in 0.1 mol / L PbCl 2 aqueous solution. After soaking for 5 min, take out the zinc sheets. Thoroughly clean the zinc sheets with deionized water, and place the zinc sheets in a constant - temperature oven, and continuously dry them at 60 °C for 10 min to obtain zinc negative electrode sheets coated with a Pb metal layer.

[0044] Example 2

[0045] First, cut zinc sheets with a size of 3.5×4.5 cm, and thoroughly clean the zinc sheets in the order of deionized water cleaning - ethanol cleaning - deionized water re - cleaning. Subsequently, fully immerse the cleaned zinc sheets in 0.1 mol / L HNO 3 solution to remove the oxide layer on the surface of the zinc sheets through pickling. After soaking for 3 min, take out the zinc sheets and thoroughly clean them with deionized water. Then, fully soak the pickled zinc sheets in 0.2 mol / L Pb(NO 3 ) 2 aqueous solution. After soaking for 5 min, take out the zinc sheets. Thoroughly clean the zinc sheets with deionized water, and place the zinc sheets in a constant - temperature oven, and continuously dry them at 50 °C for 15 min to obtain zinc negative electrode sheets coated with a Pb metal layer.

[0046] Example 3

[0047] First, cut zinc sheets with a size of 3.5×4.5 cm, and thoroughly clean the zinc sheets in the order of deionized water cleaning - ethanol cleaning - deionized water re - cleaning. Subsequently, fully immerse the cleaned zinc sheets in 0.1 mol / L CH 3 COOH solution to remove the oxide layer on the surface of the zinc sheets through pickling. After soaking for 5 min, take out the zinc sheets and thoroughly clean them with deionized water. Then, fully soak the pickled zinc sheets in 0.2 mol / L Pb(CH 3 COO) 2 aqueous solution. After soaking for 5 min, take out the zinc sheets. Thoroughly clean the zinc sheets with deionized water, and place the zinc sheets in a constant - temperature oven, and continuously dry them at 40 °C for 20 min to obtain zinc negative electrode sheets coated with a Pb metal layer.

[0048] Comparative Example

[0049] Select zinc sheets with a size of 3.5 cm×4.5 cm and the same thickness as that in Examples 1 - 3 as zinc negative electrode sheets.

[0050] Mix MnO 2 , acetylene black, and polyvinylidene fluoride (binder) evenly at a mass ratio of 80:10:10 to prepare a slurry. Coat the slurry evenly onto a nickel foam current collector (or carbon cloth current collector) to obtain a positive electrode plate. Subsequently, assemble the zinc negative electrode plates coated with Pb metal layer prepared in Example 1, Example 2, and Example 3 and the zinc negative electrode plate in the comparative example with the above positive electrode plate to obtain four different soft-pack batteries, and perform charge and discharge tests on each soft-pack battery. Charge and discharge under the voltage range of 0.8 - 1.8V and current condition of 0.1C in the test procedure. The battery test results are shown in the following table:

[0051] Test battery Initial cycle capacity (mAh) Initial cycle Coulomb efficiency (%) Capacity retention rate (%) (120 cycles) Example 1 20.8 96.01 82.2 Example 2 21.1 97.15 79.6 Example 3 20.3 96.34 71.3 Comparative example 19.3 95.03 65.3

[0052] As can be seen from the above table, for the soft-pack batteries assembled with the zinc negative electrode plates coated with Pb metal layer prepared by the method of this solution, the initial cycle capacity, initial cycle Coulomb efficiency, and capacity retention rate after 120 cycles of each example are significantly higher than those of the soft-pack batteries assembled with the zinc negative electrode plates without surface treatment. Further, please refer to Figure 1 , it can be seen that for the aqueous zinc-manganese battery assembled with the zinc negative electrode plate coated with Pb metal layer prepared by the method of this solution, when the number of cycling is less than 80, the battery cycles stably, the capacity is 17.2 mAh, the retention rate is close to 82%, and the Coulomb efficiency fluctuates little around 100%. The battery efficiency and battery performance are good. Combining Figure 2 it can be seen that the discharge specific capacity of the zinc negative electrode plate (Zn@Pb) coated with Pb metal layer is significantly better than that of the untreated bare Zn. And as the cycling progresses, the attenuation rate of the discharge specific capacity of the aqueous zinc-manganese battery assembled with the zinc negative electrode plate coated with Pb metal layer prepared by this solution is significantly slower. Under the condition of a long cycling time, it can still maintain high battery performance. When the number of cycling reaches 120, the two are close to being the same, improving the cycling stability of the battery. Combining Figure 3 and Figure 4 it can be seen that the charging platform of the zinc-manganese aqueous battery with the zinc negative electrode plate coated with Pb metal layer at the negative electrode is 1.5 - 1.6V, and the discharging platform is 1.2 - 1.6V. The reaction peaks in the dQ / dV vs. voltage relationship diagram within 120 cycles are 1.25V and 1.4V. While ensuring the battery performance, it can meet the needs of battery use.

[0053] Implement the preparation method of the negative electrode sheet of the zinc-ion battery of the present invention. Deposit a layer of lead on the surface of the zinc sheet, and wrap and cover the surface of the zinc sheet through the lead layer to achieve the protection of the battery negative electrode. It can avoid the dendrite growth caused by uneven deposition of zinc ions on the negative electrode sheet, ensure the battery performance and safety, reduce the battery internal resistance while improving the battery efficiency; through the coverage of the lead layer, the zinc sheet can be separated from water, reduce the corrosion of the negative electrode sheet, avoid the influence of corrosion by-products on the battery performance, further reduce the consumption of the negative electrode sheet and the battery internal resistance, improve the battery efficiency and the battery service life; through the protection of the lead layer on the surface of the zinc sheet, the decomposition of water during charge and discharge can be inhibited, avoid the problem of battery swelling and explosion caused by the hydrogen evolution reaction, ensure the energy density and cycle life of the battery, and ensure the normal operation of the battery.

[0054] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0055] The above-described embodiments only represent several implementation manners of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent should be subject to the appended claims.

Claims

1. A method for preparing a negative electrode sheet for a zinc ion battery, characterized in that: The following steps are involved: S1. Surface treatment of zinc sheet; S2. placing the surface-treated zinc sheet in a soluble lead salt solution and continuing the reaction for a preset time to obtain a zinc negative electrode sheet with a lead layer on the surface.

2. The method for preparing a zinc ion battery cathode sheet according to claim 1, wherein Step S1 includes: S11, cutting the zinc material into zinc sheets of a preset size; S12, cleaning the zinc sheet; S13, immersing the zinc sheet in the acid solution and continuing the reaction for a preset time; S14. Take out the zinc sheet from the acid solution and clean the zinc sheet.

3. The method for preparing a zinc ion battery cathode sheet according to claim 2, wherein: In step S12, the zinc sheet is cleaned with deionized water and ethanol.

4. The method for preparing a zinc ion battery cathode sheet according to claim 2, wherein: In step S13, the zinc sheet is immersed in a hydrogen chloride solution, and the soluble lead salt solution is a lead chloride solution.

5. The method for preparing a zinc ion battery cathode sheet according to claim 2, wherein: In step S13, the zinc sheet is immersed in a nitric acid solution, and the soluble lead salt solution is a lead nitrate solution.

6. The method for preparing a zinc ion battery cathode sheet according to claim 2, wherein: In step S13, the zinc sheet is immersed in an acetic acid solution, and the soluble lead salt solution is a lead acetate solution.

7. The method for preparing a negative electrode sheet for a zinc ion battery according to any one of claims 4 to 6, characterized in that: The solvent of the soluble lead salt solution is water, or ethylene glycol, or PVDF.

8. The method for preparing a zinc ion battery cathode sheet according to claim 1, wherein: The concentration of the soluble lead salt solution is 0.1-0.2 mol / L, and the zinc sheet is immersed in the soluble lead salt solution for 1-10 minutes.

9. The method for preparing a zinc ion battery cathode sheet according to claim 1, wherein: After step S2, the following steps are also included: S3. Take out the zinc negative electrode sheet with the lead layer on the surface from the soluble lead salt solution, and wash and dry the zinc negative electrode sheet.

10. The method for preparing a negative electrode sheet for a zinc ion battery according to claim 1, characterized in that: The thickness of the lead layer is 30 to 50 μm.

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