A high performance zinc negative electrode consisting of zinc powder and silane

Abstract

The application discloses a zinc-based slurry and a preparation method and application thereof. The zinc-based slurry comprises a silane solution and zinc powder, and the mass ratio of silane in the silane solution to the mass of the zinc powder is 6:1-8:1. The zinc-based slurry can prevent the zinc powder from being corroded by water, the silane is adhered to the surface of the zinc powder to form a protective layer, and the zinc powder is prevented from being directly corroded by water; when the zinc-based slurry is used in a battery as an electrode material, the cycle life of the battery can be prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electrode materials, in particular to a zinc-based slurry and a preparation method and application thereof. BACKGROUND

[0002] Zinc-ion secondary batteries and zinc flow batteries are two important energy storage devices based on zinc metal anodes. A typical zinc-ion secondary battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator. The positive electrode usually uses zinc-ion intercalation / deintercalation materials such as manganese dioxide and vanadium pentoxide. The negative electrode usually uses zinc metal foil as the active material. The electrolyte can be selected from zinc salt solution or polymer gel. The separator is used to prevent the positive and negative electrodes from direct contact while allowing ion transmission. Zinc-ion secondary batteries have high energy density, low cost, high safety, and environmental friendliness. On the other hand, zinc flow batteries consist of a positive electrode, a negative electrode, and an electrolyte storage tank. The positive electrode usually uses oxidizing agents such as bromine and iodine. The negative electrode uses zinc metal foil. The electrolyte storage tank contains electrolyte solution capable of transmitting ions. Zinc flow batteries have adjustable capacity, high charge-discharge efficiency, and long cycle life. It can achieve large-scale energy storage and has the ability of fast charge and discharge.

[0003] Although both of the above two zinc-based batteries currently use zinc metal foil as the negative electrode. However, the specific surface area of zinc foil is low, which is not suitable for high-power charge and discharge. In actual industrial applications, compared with zinc foil, zinc powder as the active material of the battery negative electrode has the following advantages: first, zinc powder has a large specific surface area, which allows more active material to be exposed to the electrolyte, thereby improving the reaction rate and electrochemical performance. This is very important for batteries that achieve high energy density and high power output. Second, the particle size and distribution of zinc powder can be controlled to meet different battery systems and design requirements. By controlling the microstructure of zinc powder, key performance indicators such as cycle stability, capacity retention rate, and power output of the battery can be optimized. Third, compared with zinc foil, the preparation cost of zinc powder is lower, and it can be produced using existing manufacturing technology. This makes zinc powder more feasible in industrial-scale applications and commercialization.

[0004] However, due to the large specific surface area of zinc powder, its expanded contact area makes it more susceptible to corrosion. In aqueous electrolyte, the corrosion risk of zinc powder is higher, which can lead to the reduction of battery cycle life and capacity decay. In addition, during the charging and discharging process, zinc powder will experience volume expansion and contraction, which causes mechanical stress on the electrode sheet. Due to the large surface area and high reactivity of zinc powder, this volume change can cause deformation, cracking or peeling of the electrode sheet, thereby reducing the cycle stability and life of the battery. At the same time, since zinc powder exists in the form of particles, there are gaps between the particles. During long-term use, these gaps may gradually be filled or accumulated with other substances, such as product deposits or dissolved substances in the electrolyte. This can cause the surface of the electrode sheet to become uneven, affecting the electrochemical reaction and performance of the battery.

[0005] In zinc powder negative electrode, the binder plays a very important role. The binder is a polymer material that can firmly bond zinc powder particles together and connect with the conductive current collector of the battery. Zinc powder itself is a granular material that lacks its own mechanical strength. The binder, by binding zinc powder particles together, forms a solid electrode structure, providing the necessary mechanical strength and stability, allowing the battery to remain intact and resist external stress. In addition, the binder forms a porous network structure between zinc powder particles, which can help maintain the permeability of the electrolyte. This helps the transport of zinc ions in the battery and provides a better reaction contact interface to promote the reaction. The binder can also help against the volume change problem of zinc powder during charging and discharging. It can increase the flexibility and elasticity of the electrode sheet, reducing the mechanical stress caused by the expansion and contraction of zinc powder, thereby prolonging the cycle life of the battery. SUMMARY

[0006] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present application is to overcome the high corrosion risk of zinc powder contained in zinc-based batteries in aqueous electrolyte, which leads to the reduction of battery cycle life and capacity decay.

[0007] To achieve the above-mentioned purpose, the present application provides a zinc-based slurry, the components of which include a silane solution and zinc powder, the mass ratio of silane in the silane solution to the mass of the zinc powder is 6:1-8:1.

[0008] In the present application, the silane solution can be a silane solution of conventional concentration in the art. Preferably, the volume concentration of the silane solution is 30%-50%.

[0009] In the present application, the silane solution can be prepared by conventional preparation methods in the art.

[0010] For example, the silane solution comprises a silicon-based raw material and a solvent. The volume ratio of the silicon-based raw material to the solvent can be 1:1-1:2, for example, 1:1.

[0011] The silicon-based raw material can comprise one or more of 3-(2,3-epoxypropoxy)propylmethyldimethoxysilane, 3-(2,3-epoxypropoxy)propylmethyldiethoxysilane, 3-(2,3-epoxypropoxy)propyltrimethoxysilane, 3-(2,3-epoxypropoxy)propyltriethoxysilane, and hydrolysis products thereof.

[0012] The solvent can be one or more of ethanol, NMP (N-methyl pyrrolidone), methanol, and DMF (N,N-dimethylformamide).

[0013] The silane solution can be obtained by mixing and stirring the components thereof.

[0014] In the present application, the zinc powder can be a zinc powder of a particle size commonly understood in the art. Preferably, the particle size of the zinc powder is 50 nm-1 μm.

[0015] In the present application, the mass ratio of the silane in the silane solution to the mass of the zinc powder is preferably 6:1-7:1.

[0016] In the present application, the components of the zinc-based slurry preferably further comprise an additive, which comprises one or more of carboxymethyl cellulose, carbon nanotubes, reduced graphene oxide, carbon black, and hydroxyethyl cellulose. The mass percentage of the additive is preferably 10%-40%, more preferably 20%-30%, based on the total mass of the zinc-based slurry.

[0017] The present application further provides a preparation method of the above-described zinc-based slurry. The components of the zinc-based slurry are mixed in a proportion to obtain a uniformly dispersed slurry.

[0018] In the present application, the mixing method preferably comprises ultrasonic and stirring. The ultrasonic time can be 10-20 min. The stirring time can be 10-20 min. In the present application, when the zinc-based slurry further comprises the additive, which comprises one or more of carboxymethyl cellulose, carbon nanotubes, reduced graphene oxide, carbon black, and hydroxyethyl cellulose, the components are preferably added in the form of a dispersion. The preparation method of the dispersion can be conventional in the art, and the mass concentration of the dispersion can be 0.2%-0.4%.

[0019] For example, the silane solution can be mixed with the additive first, and then mixed with the zinc powder.

[0020] The present application further provides a use of the above-described zinc-based slurry in a battery as a preparation of an electrode material.

[0021] In the present application, the zinc-based slurry can be prepared into electrode material in a conventional manner in the art, for example, the slurry of the zinc-based slurry can be coated on a titanium foil, carbon cloth, glass or polyimide film, and then dried to obtain an electrode sheet, and then prepared into a half-cell or a battery in a conventional manner in the art.

[0022] The technical solution of the present application achieves the following technical effects:

[0023] 1. The silane in the zinc-based slurry of the present application can prevent the zinc powder particles from being corroded by water, and the silane adheres to the surface of the zinc powder to form a protective layer, preventing the zinc powder from being directly corroded by water; when the zinc-based slurry is used in a battery as an electrode material, the cycle life of the battery can be prolonged.

[0024] 2. In the preferred embodiment of the present application, an additive is further added to the zinc-based slurry, which can assist in resisting the volume change problem of the zinc powder during charging and discharging, and the additive can form a silane binder with the silane solution, thereby binding the zinc powder particles together to form a solid electrode structure, increasing the flexibility and elasticity of the electrode sheet, reducing the mechanical stress caused by the expansion and contraction of the zinc powder, thereby prolonging the cycle life of the battery.

[0025] In addition, the silane binder can firmly bind the zinc powder particles together to form a porous network structure and connect with the conductive current collector of the battery, and the silane binder contains a silicon-oxygen bond in its chemical structure, which can form a stable chemical bond with the surface of the zinc powder to form a solid electrode structure, obtaining an electrode sheet with a smooth and solid surface, thereby affecting the electrochemical reaction of the battery and improving the cycle life of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a schematic diagram of the molecular structure of the silane-based binder of the present application.

[0027] Figure 2 is a photograph of the negative electrode prepared by the zinc-based slurry of the present application.

[0028] Figure 3 Zn-P symmetric battery charging and discharging cycle test.

[0029] Figure 4 Zn-P / / MnO2 full battery charging and discharging cycle test. DETAILED DESCRIPTION

[0030] The following reference to the drawings of the specification introduces a plurality of preferred embodiments of the present application, so that the technical content is more clear and convenient to understand. The present application can be embodied in many different forms of embodiments, and the protection scope of the present application is not limited to the embodiments mentioned in the text.

[0031] In the present application, in the following examples, the volume of silane is calculated by first determining the mass of silane and zinc powder, and then calculating the volume of silane based on the mass of silane contained in the silane solution: 硅烷 = V 总 * m 硅烷 / m 总 ; wherein V 总 is the total volume of the silane solution, m 总 is the total mass of the silane solution, m 硅烷 is the mass of the silane, and V 硅烷 is the volume of silane required.

[0032] In the present application, in the following examples, the particle size of the zinc powder is 1 μm.

[0033] In the present application, in the following examples, when the zinc-based slurry contains an additive, the amount of the additive can be calculated based on the total mass by the above-mentioned percentage, wherein the total mass can be weighed by means of a weighing tool.

[0034] Example 1: 2 mL of 3-glycidyloxypropylmethyldiethoxysilane was added to 2 mL of anhydrous ethanol, and 2 mL of NMP was added, and stirred for 30 min to obtain a clear silane solution. 1.5 mL of the above-mentioned silane solution was added to 3 g of zinc powder, and ultrasonic treatment was performed for 15 min, and stirring was performed for 15 min to obtain a uniform zinc-based slurry. The prepared zinc-based slurry was coated on a titanium foil, and a natural leveling method was used to completely cover the titanium foil with the slurry. Drying was performed at 100°C for 12 h to obtain an electrode sheet, as shown in Figure 2 .

[0035] Example 2: 2 mL of 3-glycidyloxypropylmethyldiethoxysilane was added to 4 mL of anhydrous ethanol, and stirring was performed for 30 min to obtain a clear silane solution. 1.5 mL of the above-mentioned silane solution was added to 0.5 g of zinc powder, and ultrasonic treatment was performed for 15 min, and stirring was performed for 15 min to obtain a uniform zinc-based slurry. The prepared zinc-based slurry was coated on a titanium foil, and a natural leveling method was used to completely cover the titanium foil with the slurry. Drying was performed at 100°C for 12 h to obtain an electrode sheet.

[0036] Example 3: 2 mL of 3-glycidyloxypropylmethyldiethoxysilane was added to 2 mL of anhydrous ethanol, and stirring was performed for 30 min to obtain a silane solution. Separately, 0.02 g of carboxymethyl cellulose was added to 10 mL of anhydrous ethanol, and stirring was performed to obtain a homogeneous dispersion to prepare a silane binder, and the molecular structure is as shown in Figure 1The 2 mL microcrystalline cellulose dispersion solution was mixed with 1.5 mL of the above silane solution, 3 g of zinc powder was added, ultrasonic treatment was performed for 15 min, stirring was performed for 15 min, and a uniform zinc-based slurry was obtained. The prepared zinc-based slurry was coated on a carbon cloth, and a natural leveling method was used to completely cover the carbon cloth with the slurry. Drying was performed at 100 °C for 12 h, and an electrode sheet was obtained.

[0037] In Example 4, 2 mL of 3-glycidyloxypropylmethyldiethoxysilane was added to 2 mL of anhydrous ethanol, and stirring was performed for 30 min to obtain a silane solution. 0.02 g of carbon nanotubes was added to 10 mL of NMP, stirring was performed to obtain a homogeneous dispersion solution, and a silane binder was prepared, and the molecular structure is as shown in Figure 1 The 2 mL carbon nanotube dispersion solution was mixed with 1.5 mL of the silane solution, 0.5 g of zinc powder was added, ultrasonic treatment was performed for 15 min, stirring was performed for 15 min, and a uniform zinc-based slurry was obtained. The prepared zinc-based slurry was coated on a glass, and a natural leveling method was used to completely cover the glass with the slurry. Drying was performed at 100 °C for 12 h, and a self-supporting electrode sheet was obtained by peeling the dried coating from the surface of the glass.

[0038] In Example 5, 2 mL of 3-glycidyloxypropylmethyldiethoxysilane was added to 2 mL of anhydrous ethanol, and stirring was performed for 30 min to obtain a silane solution. 0.02 g of reduced graphene oxide powder was added to 10 mL of anhydrous ethanol, and stirring was performed at 60 °C to obtain a homogeneous dispersion solution. The 2 mL reduced graphene oxide dispersion solution was mixed with 1.5 mL of the silane solution, 3 g of zinc powder was added, ultrasonic treatment was performed for 15 min, stirring was performed for 15 min, and a uniform zinc-based slurry was obtained. The prepared zinc-based slurry was coated on a polyimide film, and a natural leveling method was used to completely cover the polyimide film with the slurry. Drying was performed at 100 °C for 12 h, and a self-supporting electrode sheet was obtained by peeling the dried coating from the surface of the polyimide film.

[0039] In Example 6, 2 mL of 3-glycidyloxypropylmethyldiethoxysilane was added to 2 mL of anhydrous ethanol, and stirring was performed for 30 min to obtain a silane solution. 0.02 g of carbon black and 0.02 g of hydroxyethyl cellulose were added to 10 mL of a mixed solvent of anhydrous ethanol and NMP (volume ratio 1:1), and stirring was performed at 60 °C to obtain a homogeneous dispersion solution. The 2 mL dispersion solution was mixed with 1.5 mL of the above silane solution, 0.5 g of zinc powder was added, ultrasonic treatment was performed for 15 min, stirring was performed for 15 min, and a uniform zinc-based slurry was obtained. The prepared zinc-based slurry was coated on a polyimide film, and a natural leveling method was used to completely cover the polyimide film with the slurry. Drying was performed at 100 °C for 12 h, and a self-supporting electrode sheet was obtained by peeling the dried coating from the surface of the polyimide film.

[0040] Example 7: Performance test of zinc-based slurry: the performance of the zinc-based slurry prepared in the present application was tested by making a half-cell from the zinc-based slurry in a conventional manner in the art, and performing charge-discharge experiments to understand the cycle performance of the material. The electrode prepared by the above method was used as the anode, glass fiber material was used as the separator, and Zn(OTf)2electrolyte was injected, and then the electrode was pressed into a CR2016 button cell (Zn-P symmetric cell) by a machine. After standing for 12 h, the constant current charge-discharge test was performed on a blue cell test system (discharged at a current of 1 mA for 1 h, and then charged at a current of 1 mA for 1 h, and the cycle was repeated), and the test results are shown in Figure 3 As shown in Figure 3 , the Zn-P symmetric cell prepared from the zinc-based slurry of the present application achieved a reversible cycle of up to 40 hours.

[0041] Example 8: Performance test of zinc-based slurry: the performance of the zinc-based slurry prepared in the present application was tested by making a full cell from the zinc-based slurry in a conventional manner in the art, and performing charge-discharge experiments to understand the cycle performance of the material. The electrode prepared by the above method was used as the anode, glass fiber material was used as the separator, and Zn(OTf)2electrolyte was injected, and then the electrode was pressed into a CR2016 button cell (Zn-P / / MnO2full cell) by a machine. After standing for 12 h, the constant current charge-discharge test was performed on a blue cell test system (discharged at a current of 1 A / g to a cell voltage of 1.0 V, and then charged at a current of 1 A / g to a cell voltage of 1.8 V, and the cycle was repeated), and the test results are shown in Figure 4 .

[0042] The preferred embodiments of the present application are described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and changes to the present application without creative work based on the concept of the present application. Therefore, any technical solutions obtained by logical analysis, reasoning or limited experiments by those skilled in the art based on the concept of the present application on the basis of the prior art shall be within the scope of protection determined by the claims.

Claims

1. A zinc-based slurry characterized in that, The components of the zinc-based slurry include a silane solution and zinc powder, and the mass ratio of silane in the silane solution to the mass of the zinc powder is 6:1-8:

1.

2. The zinc-based slurry of claim 1, wherein, The volume concentration of the silane solution is 30%-50%.

3. The zinc-based slurry of claim 1, wherein, The silicon-based raw material in the silane solution includes one or more of 3-(2,3-epoxypropoxy) propyl methyl dimethoxysilane, 3-(2,3-epoxypropoxy) propyl methyl diethoxysilane, 3-(2,3-epoxypropoxy) propyl trimethoxysilane, 3-(2,3-epoxypropoxy) propyl triethoxysilane, and hydrolysis products thereof.

4. The zinc-based slurry of claim 1, wherein, The particle size of the zinc powder is 50 nm-1 μm.

5. The zinc-based slurry of claim 1, wherein, The mass ratio of silane in the silane solution to the mass of the zinc powder is 6:1-7:

1.

6. The zinc-based slurry of claim 1, wherein, The components of the zinc-based slurry further include an additive, and the additive includes one or more of carboxymethyl cellulose, carbon nanotubes, reduced graphene oxide, carbon black, and hydroxyethyl cellulose.

7. The zinc-based slurry of claim 6, wherein, The mass percentage of the additive is 10%-40% based on the total mass of the zinc-based slurry.

8. The zinc-based slurry of claim 7, wherein, The mass percentage of the additive is 20%-30% based on the total mass of the zinc-based slurry.

9. A process for the preparation of a zinc-based slurry as claimed in any one of claims 1 to 8, characterized in that, The components of the zinc-based slurry are mixed in a proportion to obtain a uniformly dispersed slurry.

10. Use of the zinc-based slurry according to any one of claims 1-8 in a battery as a preparation of electrode material.

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