Method for improving charge-discharge performance of tin-air battery

Abstract

The invention relates to the technical field of electrochemistry, in particular to a method for improving the charge-discharge performance of a tin-air battery. A trace amount of urea is added into the electrolyte and the carbon cloth substrate is pretreated, so that amide groups (C = O and-NH) in urea molecules can interact with the carbon cloth substrate, and two H atoms of urea tend to be oriented towards two O atoms of Sn (OH) 3-, so that adsorption of Sn (OH) 3-on the carbon substrate in the electrolyte is enhanced; the problems of tin death, hydrogen evolution and the like of a current tin-air battery charge-discharge anode are solved, the service life of the battery is prolonged, the reliability of the battery is improved, low-cost and high-performance development of the tin-air battery can be promoted, and the commercialized application process of the tin-air battery is greatly promoted.

Description

Technical Field

[0001] The invention relates to the technical field of electrochemistry, and in particular to a method for improving the charging and discharging performance of a tin-air battery. Background Art

[0002] The research and development of electrochemical energy conversion and storage devices, especially high-performance batteries, is one of the scientific attempts of mankind to explore the utilization of green energy and deal with the energy crisis. Metal-air batteries are considered to be one of the important candidates for the next generation of battery systems because of their high theoretical specific energy (about 3-30 times that of lithium-ion batteries). This type of battery usually consists of pure metal as the negative electrode active material and O in the air. 2 As the positive electrode active material, it is a semi-open battery system between traditional batteries and fuel cells. According to the type of electrolyte, metal-air batteries can be divided into two categories: non-aqueous organic systems and aqueous systems. Typical non-aqueous organic systems include lithium-air batteries, sodium-air batteries and potassium-air batteries, with theoretical energy densities of up to 11410Wh / kg, 2677Wh / kg and 1622Wh / kg, respectively. However, the inherent safety issues caused by the flammability of organic electrolytes and the high activity of alkali metal negative electrodes are the ultimate problems that need to be faced in their future applications. In comparison, based on the inherent non-flammability and explosion, high ionic conductivity, low cost and environmental friendliness of aqueous electrolytes, aqueous metal-air batteries have inherent high safety, simple assembly process, high power characteristics and low cost advantages. Therefore, the development of metal-air batteries based on aqueous electrolyte systems has practical significance.

[0003] Metallic tin (Sn) has the advantages of low cost, non-toxicity, and good biocompatibility, and has been widely used in energy storage in lithium-ion batteries and sodium-ion batteries. The tin metal anode has a capacity of 903 mAh g -1 High theoretical specific capacity, theoretical energy density up to 1174Wh kg -1 . However, the application of tin anodes in rechargeable aqueous batteries (SABs) remains a challenge due to the short cycle life of aqueous tin-air batteries (SABs) during repeated tin plating / stripping processes. Fundamentally, the uneven tin plating / stripping process causes uneven accumulation of tin particles on the electrode surface, forming large particles or agglomerations. This uneven deposition and stripping can cause some tin particles to fail to be completely stripped during the discharge process, and then gradually lose their electrochemical activity to form "dead tin". In addition, Sn has poor thermodynamic stability in alkaline aqueous solutions. In alkaline electrolytes, the high overpotential of the Sn anode during the stripping process easily produces hydrogen evolution reaction, which is also the main reason for the low reversibility of the tin anode.

[0004] In view of this, the present invention is proposed to solve the interface problem of SABs without sacrificing the properties of the bulk electrolyte. Summary of the invention

[0005] In order to overcome the above technical defects, the present invention provides a tin-air battery and a method for improving the charge and discharge performance of the tin-air battery to solve the problem of poor reversibility of the tin-air electrode anode.

[0006] One of the purposes of the present invention is to provide a method for improving the charge and discharge performance of a tin-air battery, comprising the following steps:

[0007] S1. The carbon cloth is sequentially placed in hydrochloric acid and deionized water, ultrasonically cleaned, and dried to obtain a clean substrate;

[0008] S2. Assemble the clean substrate prepared in S1 on the anode side of the battery. After assembling the battery, conduct 5 mA cm -2 After charging for 1 h under the above conditions, a tin anode with carbon cloth as the substrate was obtained;

[0009] S3. The alkaline hydroxide, the organic additive, the tin salt and water to obtain an anode side electrolyte;

[0010] S4. Assemble a tin-air battery with a tin anode, an anode-side electrolyte, a separation membrane, a cathode-side electrolyte and an air battery cathode.

[0011] In some embodiments, S1 is specifically: placing the carbon cloth in a dilute hydrochloric acid solution and ultrasonicating it for 20-30 minutes, placing it in deionized water and ultrasonicating it for 20-30 minutes, and finally drying it in an oven at 60° C. for 1 hour to obtain a clean carbon cloth substrate.

[0012] In some embodiments, S2 is specifically: the cleaned carbon cloth is used as a substrate to be assembled on the anode side of the battery, the N117 proton membrane is used as a diaphragm, and Pt / C, RuO 2 After mixing, the organic solvent and the binder are coated on the conductive composite substrate as the air cathode, the composite electrolyte is used as the electrolyte on the anode side, and the KOH solution is used as the electrolyte on the cathode side. After assembling into a battery, the battery is charged at 5 mA cm -2 After charging for 1 h under the above conditions, a tin anode with carbon cloth as the substrate was obtained.

[0013] In some embodiments, in S3, on a molar basis, the organic additive concentration is 0.01-1M, or 0.05-1M, or 0.08-1M, or 0.01-0.5M, or 0.03-0.2M, or 0.05-0.1M; the alkaline hydroxide concentration is 1-12M, or 1-10M, or 1-8M, or 1-5M, or 1-3M; the tin salt concentration is 0.01-1M, or 0.05-1M, or 0.08-1M, or 0.01-0.5M, or 0.03-0.2M, or 0.05-0.1M.

[0014] In some embodiments, the alkaline hydroxide is selected from one or more of lithium hydroxide, sodium hydroxide, and potassium hydroxide;

[0015] In a preferred embodiment of the present invention, the alkaline hydroxide is selected from potassium hydroxide.

[0016] In some embodiments, the organic additive is selected from one or more of urea, formamide, acetamide, caprolactam, and nicotinamide;

[0017] In a preferred embodiment of the present invention, the organic additive is selected from urea.

[0018] In some embodiments, the tin salt is selected from a mixture of one or more soluble salts of stannate or stannate, tin or stannous salts;

[0019] In a preferred embodiment of the present invention, the tin salt is selected from SnSO 4 .

[0020] In some embodiments, the air battery cathode is prepared by the following method: Pt / C, RuO 2 The organic solvent and the binder are mixed and then coated on a conductive composite substrate to obtain the product.

[0021] In some embodiments, the Pt / C, RuO 2 The mass volume ratio of the organic solvent and the binder is (0.1-1) mg:(0.1-2) mg:(50-200) μL:(50-200) μL.

[0022] In a preferred embodiment of the present invention, the organic solvent is selected from isopropanol, the binder is selected from Nafion; the Pt / C, RuO 2 The mass volume ratio of , isopropanol, and nafion is 1 mg:0.2 mg:100 μL:100 μL.

[0023] In some embodiments, the conductive composite substrate is formed by rolling nickel foam, a PTFE waterproof layer and carbon paper.

[0024] One of the purposes of the present invention is to provide a tin-air battery prepared by the above method.

[0025] Beneficial effect: By adding a trace amount of urea to the electrolyte and pretreating the carbon cloth substrate, the amide groups (C=O and -NH) in the urea molecule can interact with the carbon cloth substrate, and the two H atoms of the urea tend to move toward Sn(OH) 3 - The two O atoms of 3 -Adsorption on the carbon substrate solves the current problems of dead tin and hydrogen evolution in the charging and discharging anode of tin-air batteries, improves battery life and reliability, and can help develop low-cost, high-performance tin-air batteries, greatly promoting the commercial application of tin-air batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a graph showing the electrochemical polarity curve measurement results of the present invention;

[0027] Figure 2 This is a scanning electron microscope characterization result diagram of the carbon cloth surface of the tin-air battery of the present invention;

[0028] Among them, 2a is the SEM image of Example 2, and 2b is the SEM image of Comparative Example 1;

[0029] Figure 3 This is a cycle test diagram of the tin-air battery of the present invention. DETAILED DESCRIPTION

[0030] In order to make those skilled in the art better understand the technical solution of the present invention, the present invention is described in detail below in conjunction with specific embodiments. The experimental methods in the following examples that do not specify specific conditions are usually based on conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, percentages and parts are calculated by weight. Unless otherwise defined, all professional and scientific terms used in the text have the same meanings as those familiar to those skilled in the art. In addition, any method and material similar or equivalent to the recorded content can be applied to the present invention. The preferred implementation methods and materials described in the text are for demonstration purposes only.

[0031] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0032] Example 1 Investigation of the Hydrogen Evolution Corrosion Inhibition Performance of the Composite Electrolyte

[0033] Urea was used as an electrolyte additive and prepared into a composite electrolyte with potassium hydroxide aqueous solution to carry out a kinetic Tafel test on tin anode, verifying that urea has the effect of inhibiting hydrogen evolution corrosion.

[0034] Two groups of composite electrolytes were prepared for the experimental group and the control group, and the kinetic polarization curve was measured by three electrodes, using the tin anode as the working electrode, Hg / HgO as the reference electrode, and the graphite rod as the counter electrode. Test results (see Figure 1); Experimental group: 33.7 g KOH, 0.1 M SnSO 4 , 0.1M urea to prepare 200mL composite electrolyte; control group: 33.7g KOH, 0.1M SnSO 4 Prepare 200mL of composite electrolyte.

[0035] like Figure 1 As shown, the corrosion potential of Example 1 (-1.04V) is greater than the corrosion current of Comparative Example 1 (-1.05V), which indicates that the addition of urea reduces the damage of KOH to the tin anode; the corrosion potential of Comparative Example 1 is smaller, indicating that the corrosion of tin is aggravated.

[0036] Example 2 Tin-air battery

[0037] Preparation of carbon cloth substrate: put the carbon cloth into a dilute hydrochloric acid solution for ultrasonication for 20-30 minutes, then put it into deionized water for ultrasonication for 20-30 minutes, and finally dry it in an oven at 60°C for 1 hour to obtain a clean carbon cloth substrate;

[0038] Preparation of air cathode: 4 mg Pt / C, 1 mg RuO 2 After the catalysts are mixed, 400 μL of Nafion solution and 400 μL of isopropanol are added to the beaker in turn, and the mixed solution is dispersed by ultrasonication to prepare a slurry, and then the slurry is coated on the surface of the conductive composite substrate and dried naturally to obtain an air cathode; wherein the conductive composite substrate is formed by rolling nickel foam, PTFE waterproof layer and carbon paper;

[0039] Preparation of tin anode: The cleaned carbon cloth is used as a substrate to assemble on the anode side of the battery, N117 proton membrane is used as a separator, Pt / C, RuO 2 After mixing, the organic solvent and the binder are coated on the conductive composite substrate as the air cathode, the composite electrolyte is used as the electrolyte on the anode side, and the KOH solution is used as the electrolyte on the cathode side. After assembling into a battery, the battery is charged at 5 mA cm -2 After charging for 1 h under the above conditions, a tin anode with carbon cloth as the substrate was obtained.

[0040] Preparation of electrolyte: 0.1 mol urea, 3 mol KOH, 0.1 mol SnSO 4 A composite electrolyte was prepared with 1L water as the electrolyte on the anode side, and a 3M KOH solution was used as the electrolyte on the cathode side;

[0041] Air battery assembly: Assemble a tin anode, an anode-side electrolyte, a separation membrane, a cathode-side electrolyte and an air battery cathode into a tin-air battery.

[0042] Comparative Example 1

[0043] Preparation of carbon cloth substrate: put the carbon cloth into a dilute hydrochloric acid solution for ultrasonication for 20-30 minutes, then put it into deionized water for ultrasonication for 20-30 minutes, and finally dry it in an oven at 60°C for 1 hour to obtain a clean carbon cloth substrate;

[0044] Preparation of air cathode: 4 mg Pt / C, 1 mg RuO 2 After the catalysts are mixed, 400 μL of Nafion solution and 400 μL of isopropanol are added to the beaker in turn, and the mixed solution is dispersed by ultrasonication to prepare a slurry, and then the slurry is coated on the surface of the conductive composite substrate and dried naturally to obtain an air cathode; wherein the conductive composite substrate is formed by rolling nickel foam, PTFE waterproof layer and carbon paper;

[0045] Preparation of tin anode: The cleaned carbon cloth is used as a substrate to assemble on the anode side of the battery, N117 proton membrane is used as a separator, Pt / C, RuO 2 After mixing, the organic solvent and the binder are coated on the conductive composite substrate as the air cathode, the composite electrolyte is used as the electrolyte on the anode side, and the KOH solution is used as the electrolyte on the cathode side. After assembling into a battery, the battery is charged at 5 mA cm -2 After charging for 1 h under the above conditions, a tin anode with carbon cloth as the substrate was obtained.

[0046] Preparation of electrolyte: 3 mol KOH, 0.1 mol SnSO 4 A composite electrolyte was prepared with 1L water as the electrolyte on the anode side, and a 3M KOH solution was used as the electrolyte on the cathode side;

[0047] Air battery assembly: Assemble a tin anode, an anode-side electrolyte, a separation membrane, a cathode-side electrolyte and an air battery cathode into a tin-air battery.

[0048] Comparative Example 2

[0049] Preparation of air cathode: 4 mg Pt / C, 1 mg RuO 2 After the catalysts are mixed, 400 μL of Nafion solution and 400 μL of isopropanol are added to the beaker in turn, and the mixed solution is dispersed by ultrasonication to prepare a slurry, and then the slurry is coated on the surface of the conductive composite substrate and dried naturally to obtain an air cathode; wherein the conductive composite substrate is formed by rolling nickel foam, PTFE waterproof layer and carbon paper;

[0050] Preparation of tin anode: Untreated carbon cloth was used as a substrate to assemble on the anode side of the battery, N117 proton membrane was used as a separator, Pt / C, RuO 2 After mixing, the organic solvent and the binder are coated on the conductive composite substrate as the air cathode, the composite electrolyte is used as the electrolyte on the anode side, and the KOH solution is used as the electrolyte on the cathode side. After assembling into a battery, the battery is charged at 5 mA cm -2After charging for 1 h under the above conditions, a tin anode with carbon cloth as the substrate was obtained.

[0051] Preparation of electrolyte: 0.1 mol urea, 3 mol KOH, 0.1 mol SnSO 4 A composite electrolyte was prepared with 1L water as the electrolyte on the anode side, and a 3M KOH solution was used as the electrolyte on the cathode side;

[0052] Air battery assembly: Assemble a tin anode, an anode-side electrolyte, a separation membrane, a cathode-side electrolyte and an air battery cathode into a tin-air battery.

[0053] The tin-air batteries prepared in the comparative example and the embodiment were tested for charge and discharge performance:

[0054] At 5mAcm -2 After charging for 1 h at the current density, the carbon cloth surface was tested by scanning electron microscopy (see Figure 2 ).

[0055] from Figure 2 It can be seen that the carbon cloth surface of the tin-air battery of the present invention has a large amount of tin ( Figure 2 a), this is because the two H atoms of urea tend to move toward Sn(OH) 3 - The orientation of the two O atoms is mainly attributed to the urea and Sn(OH) 3 - The favorable orbital matching between them enhances the Sn(OH) 3 - Adsorption on the carbon substrate; while the carbon cloth surface of the tin-air battery prepared in the comparative example has less tin loaded ( Figure 2 b) This is because there is no additional H atom adsorbing Sn(OH) in the electrolyte without additives. 3 - , which results in the Sn(OH) 3 - The adsorption of tin is reduced, so that less tin is loaded on the carbon cloth.

[0056] At a current density of 5 mA cm -2 Long-term charge and discharge cycle test (see Figure 3 ).like Figure 3 As shown in the figure, the cycle time of the tin-air battery of the present invention is 360h, while the tin-air battery prepared in the comparative example has dead tin after 50h and 90h of cycle, causing the battery to stop working. This is because urea and Sn(OH) 3 - The favorable orbital matching between them enhances the Sn(OH) 3 -Adsorption on the carbon substrate reduces the generation of dead tin and significantly increases the cycle time.

[0057] Finally, it should be noted that the above description is only a preferred embodiment of the present invention. Under the guidance of the present invention, those skilled in the art can make a variety of similar expressions without violating the purpose and claims of the present invention. Such changes all fall within the scope of protection of the present invention.

Claims

1. A method for improving the charge and discharge performance of a tin-air battery, characterized in that: The following steps are involved: S1. The carbon cloth is sequentially placed in hydrochloric acid and deionized water, ultrasonically cleaned, and dried to obtain a clean substrate; S2. Assemble the clean substrate prepared in S1 on the anode side of the battery. After assembling the battery, conduct 5 mA cm -2 After charging for 1 h under the above conditions, a tin anode with carbon cloth as the substrate was obtained; S3. The alkaline hydroxide, the organic additive, the tin salt and water to obtain an anode side electrolyte; S4. Assemble a tin-air battery with a tin anode, an anode-side electrolyte, a separation membrane, a cathode-side electrolyte and an air battery cathode.

2. The method according to claim 1, characterized in that The S1 is specifically as follows: placing the carbon cloth in a dilute hydrochloric acid solution for ultrasonic treatment for 20-30 minutes, placing the carbon cloth in deionized water for ultrasonic treatment for 20-30 minutes, and finally drying the carbon cloth in an oven at 60° C. for 1 hour to obtain a clean carbon cloth substrate.

3. The method according to claim 1, characterized in that In S3, in terms of molar concentration, the concentration of the organic additive is 0.01-1M, or 0.05-1M, or 0.08-1M, or 0.01-0.5M, or 0.03-0.2M, or 0.05-0.1M; the concentration of the alkaline hydroxide is 1-12M, or 1-10M, or 1-8M, or 1-5M, or 1-3M; the concentration of the tin salt is 0.01-1M, or 0.05-1M, or 0.08-1M, or 0.01-0.5M, or 0.03-0.2M, or 0.05-0.1M.

4. The method according to claim 1, characterized in that: The alkaline hydroxide is selected from one or more of lithium hydroxide, sodium hydroxide and potassium hydroxide; preferably, it is selected from potassium hydroxide.

5. The method according to claim 1, characterized in that The organic additive is selected from one or more of urea, formamide, acetamide, caprolactam and nicotinamide; preferably, it is selected from urea.

6. The method according to claim 1, characterized in that The tin salt is selected from a mixture of one or more soluble salts of stannates or stannates, tin or stannous salts; preferably, it is selected from SnSO4.

7. The method according to claim 1, characterized in that The air battery cathode is prepared by the following method: Pt / C, RuO2, an organic solvent and a binder are mixed and then coated on a conductive composite substrate.

8. The method according to claim 7, characterized in that The mass volume ratio of the Pt / C, RuO2, organic solvent, and binder is (0.1-1) mg: (0.1-2) mg: (50-200) μL: (50-200) μL.

9. The method according to claim 7, characterized in that: The conductive composite substrate is formed by rolling nickel foam, a PTFE waterproof layer and carbon paper.

10. A tin-air battery, characterized in that: The method according to claim 1 is adopted to prepare the present invention.

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