Aqueous tin ion battery electrolyte and battery

Abstract

The invention relates to an aqueous tin ion battery electrolyte and a battery, and belongs to the technical field of aqueous tin ion batteries. The electrolyte is prepared by mixing and stirring tin salt, acid, an additive and a solvent. Water serves as a main solvent, safety is high, and raw materials are easy to obtain. The selected tin salt is tin acetate, acetate and Sn < 2 + > are subjected to coordination, a solvation structure is adjusted, and uniform deposition / stripping of tin on the surface of the electrode is promoted. The selected additives comprise three types of substances including deacetylated chitin, mercaptoacetic acid and ammonium acetate. Under different current density conditions, the electrolyte can achieve the excellent performance that the first-circle coulombic efficiency (CE) exceeds 98%. The characteristic shows that the electrolyte effectively inhibits the occurrence of side reactions, and the stability of an electrode / electrolyte interface is greatly improved. In addition, the electrolyte is simple in preparation process and low in cost, and shows a good application prospect.

Description

Technical Field

[0001] The present invention relates to a novel preparation of aqueous battery electrolyte, in particular to a preparation technology of aqueous tin ion battery acidic electrolyte, belonging to the field of aqueous tin ion battery manufacturing. Background Art

[0002] With the rapid development of renewable energy, efficient and environmentally friendly energy storage technologies have become particularly important. Batteries, as a key energy storage device, play a vital role in portable electronic devices, electric vehicles, and large-scale grid energy storage. Currently, lithium-ion batteries are widely available. They have high energy density and long cycle life, but lithium resources are relatively scarce and unevenly distributed, which will lead to an increase in their cost. Lithium-ion batteries also have safety issues that may cause the battery to catch fire and explode. Among the many battery technologies, tin-ion batteries have attracted widespread attention due to their advantages such as high theoretical specific capacity, low cost, and high safety.

[0003] Among the commonly used aqueous tin-ion battery electrolyte systems, the H2SO4+SnSO4 electrolyte is the most common. However, this electrolyte has obvious drawbacks. As a strong acid, H2SO4 is highly corrosive to the electrodes and can cause severe hydrogen evolution reactions, severely affecting the cycle life of aqueous tin-ion batteries. Summary of the Invention

[0004] To this end, the present invention has developed a new acidic electrolyte formula. On the one hand, acetic acid, as a weak acid, has less corrosion to the electrode than H2SO4 in the traditional H2SO4+SnSO4 electrolyte system, is cheaper, and has a higher safety factor. At the same time, CH3COO − The electron-donating -CH3 in the 2+ Form coordination and effectively improve Sn 2+ The solvation structure of the electrode is significantly improved, thereby significantly improving the stability of the electrode interface; on the other hand, by introducing a composite additive system (deacetylated chitosan, thioglycolic acid and ammonium acetate), a multifunctional protective layer is constructed on the electrode surface: deacetylated chitosan can be adsorbed on the electrode surface to form a protective layer, which can guide the uniform deposition of tin, and thioglycolic acid can inhibit Sn through complexation. 2+ Hydrolysis occurs, and ammonium acetate can also cross-link with chitosan, enhancing the mechanical strength of the interface. Ammonium acetate acts as a pH buffer, promoting electrolyte stability. This electrolyte system significantly suppresses side reactions such as hydrogen evolution while maintaining high ionic conductivity, significantly improving battery cycle life. The developed electrolyte formulation is simple to manufacture and low-cost. The assembled aqueous tin-ion battery exhibits excellent electrochemical performance, demonstrating significant research value and application prospects.

[0005] The present invention proposes a new acidic electrolyte formula suitable for aqueous tin ion batteries. By optimizing the tin salt, acid and composite additive system, the deposition / stripping reversibility and interfacial stability of the tin negative electrode are significantly improved. The present invention uses water as the main solvent, tin acetate as the tin salt, and uses acetate to react with Sn. 2+ The coordination effect of tin regulates the uniform deposition behavior of tin, and combined with the synergistic effect of deacetylated chitosan, thioglycolic acid and ammonium acetate, a highly stable composite interface layer is constructed on the electrode surface.

[0006] The presence of amino (-NH2) and hydroxyl (-OH) functional groups in chitosan allows it to adsorb onto the electrode surface to form a protective layer, guiding the uniform deposition of tin. Thioglycolic acid inhibits electrolyte hydrolysis through complexation and can undergo a cross-linking reaction with chitosan, enhancing the mechanical strength of the interface and effectively inhibiting dendrite formation and side reactions. Ammonium acetate acts as a pH buffer to maintain system stability. Sn||Cu half-cells assembled using this electrolyte exhibit an initial coulombic efficiency exceeding 98% and exhibit excellent cycling stability at various current densities. The electrolyte provided by the present invention has a simple formulation and process, is low-cost, and provides an effective solution to addressing issues such as interface instability and short cycle life of the negative electrode in aqueous tin ion batteries, promising broad prospects for industrial application.

[0007] The technical solution of the present invention comprises the following steps: A method for preparing an aqueous tin ion battery electrolyte comprises the following steps: (1) adding a tin salt to the acetic acid solution prepared in step (1), stirring and mixing thoroughly to obtain an acidic tin salt solution; (2) Ammonium acetate, thioglycolic acid solution, and deacetylated chitosan solution are sequentially added to the acidic tin salt solution of step (1) and stirred evenly to obtain a tin ion battery electrolyte.

[0008] The concentration of the acetic acid solution is 0.5-18 M, and the pH of the acidic tin salt solution is controlled to be 1-2.

[0009] The tin salt includes one or more of tin acetate, tin sulfate, tin chloride, tin fluoborate, tin pyrophosphate, tin oxalate or tin trifluoromethanesulfonate; the concentration of the tin salt is 0.5-2 M.

[0010] The mass fraction of ammonium acetate is 1-3%, preferably 1-2%.

[0011] The mass fraction of the thioglycolic acid solution is 1-5%, preferably 1-3%, and the concentration of the thioglycolic acid solution is 0.1-0.5 M.

[0012] The mass fraction of the chitosan solution is 0.5-2%, preferably 0.5-1%.

[0013] On the other hand, the present invention also provides an aqueous tin ion battery electrolyte, characterized in that it includes an electrolyte prepared by the method described in any one of claims 1 to 6, mainly using water as the main solvent, the concentration of tin ions as the effective active ingredient in the electrolyte is 0.5-2 M, the pH of the electrolyte is controlled in the range of 1-2, and the electrolyte is clear and transparent.

[0014] On the other hand, the present invention also provides a tin symmetrical battery or a tin asymmetrical battery, characterized in that it comprises the aqueous tin ion battery electrolyte.

[0015] On the other hand, the present invention also provides a Sn||Cu half-cell, comprising the aqueous tin ion battery electrolyte.

[0016] On the other hand, the present invention also provides a tin ion electrochemical energy storage device using the electrolyte. The tin ion electrochemical energy storage device is an aqueous secondary battery containing tin ions or an aqueous battery capacitor containing tin ions.

[0017] The positive electrode material of the aqueous battery capacitor containing tin ions is a metal material selected from at least one of copper foil, stainless steel and titanium mesh; the negative electrode active material is tin foil, and the diaphragm is a glass fiber diaphragm.

[0018] Compared with the prior art, the advantages and beneficial effects of the present invention are: 1. The present invention uses acetic acid as the acidic substance in the electrolyte. As a weak acid, acetic acid has weak corrosiveness to the electrode, and CH3COO in acetic acid - Due to the presence of -CH3 electron-donating group, it can better react with Sn 2+ Form coordination and regulate the solvation structure, so that tin ions can be uniformly deposited / stripped on the electrode surface.

[0019] 2. By adding a variety of functional additives, a composite electrode / electrolyte interface with higher mechanical strength is formed on the electrode surface through synergistic action. Deacetylated chitosan is used as an electrolyte additive. This compound has multiple functional groups that can be adsorbed on the electrode surface to promote uniformity of deposition. Thioglycolic acid can cross-link with deacetylated chitosan to improve the stability of the electrode / electrolyte interface. At the same time, ammonium acetate can act as a pH buffer to reduce local pH fluctuations, maintain electrolyte stability, and enable the battery to have a longer cycle life.

[0020] 3. The new electrolyte has a longer cycle life than commonly used electrolytes. Testing using a Sn||Cu half-cell demonstrated a coulombic efficiency of 98% in the first cycle, demonstrating excellent cycling performance. The preparation method is simple and has promising application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Example 1 of the present invention at 0.5 mA cm -2 ,0.5 mAh cm -2 Cyclic performance diagram under .

[0022] Figure 2 Example 1 of the present invention at 1 mA cm -2 ,0.5 mAh cm -2 Cyclic performance diagram under .

[0023] Figure 3 Example 2 of the present invention at 0.5 mA cm -2 ,0.5 mAh cm -2 Cyclic performance diagram under .

[0024] Figure 4 Example 3 of the present invention at 0.5 mA cm -2 ,0.5 mAh cm -2 Cyclic performance diagram under .

[0025] Figure 5 For comparative example 1 at 0.5 mA cm -2 ,0.5 mAh cm -2 Cyclic performance diagram under .

[0026] Figure 6 For comparative example 1 at 1 mA cm -2 ,0.5 mAh cm -2 Cyclic performance diagram under .

[0027] Figure 7 Comparative Example 1 of the present invention at 0.5 mA cm -2 , 0.5 mAh cm -2 Cyclic performance diagram under .

[0028] Figure 8 Comparative Example 2 of the present invention at 0.5 mA cm -2 , 0.5 mAh cm -2 Cyclic performance diagram under .

[0029] Figure 9 Comparative Example 3 of the present invention is 0.5 mA cm -2 , 0.5 mAh cm -2 Cyclic performance diagram under .

[0030] Figure 10These are digital photos of the electrolytes of Example 1 and Comparative Example 1 of the present invention after being placed for one month. (a) is a photo of the electrolyte of Example 1, with the left side showing the freshly prepared electrolyte and the right side showing the electrolyte after being placed for one month. (b) is a photo of the electrolyte of Comparative Example 1, with the left side showing the freshly prepared electrolyte and the right side showing the electrolyte after being placed for one month.

[0031] Figure 11 The optical microscope photos of Example 1, Comparative Example 1 and the original tin foil in the present invention are shown in Figure 1. (a) is a photo of the original tin foil, and (b) and (c) are photos of the electrolyte in Example 1 and Comparative Example 1 at 0.5 mA cm -2 ,0.5 mAh cm -2 Optical microscope photograph of the Sn||Cu half-cell after 10 cycles under the same conditions. DETAILED DESCRIPTION

[0032] In the embodiment, the aqueous tin ion battery assembly includes a positive electrode material, an electrolyte, a separator, and a negative electrode material. The positive electrode material is copper foil, the negative electrode material is tin foil, and the separator is a glass fiber separator.

[0033] Example 1 The preparation method of 1 M acetic acid solution used in the embodiment is: First add 4.7143 mL of deionized water, then add 0.2857 mL of pure acetic acid and stir evenly.

[0034] The preparation method of 0.1 M thioglycolic acid solution used in the embodiment is: First add 4.9625 mL of deionized water, then add 0.0348 mL of pure thioglycolic acid and stir well.

[0035] Preparation method of the electrolyte of the aqueous tin ion battery in this embodiment: At room temperature, add 1 mL of 1 M acetic acid solution to a glass bottle, and add 0.1184 g of tin acetate. After mixing, stabilize the pH of the electrolyte in the range of 1-2, then add 0.01 g of ammonium acetate, and then use a pipette to transfer 0.03 mL of 0.1 M thioglycolic acid solution and stir evenly. Finally, add 0.005 g of deacetylated chitosan and stir on a magnetic stirrer until the electrolyte is clear to obtain 1 M CH3COOH+0.5 M Sn(CH3COO)2+NH4OAc+TGA+CS.

[0036] The above electrolyte formulation was installed as a Sn||Cu half-cell for electrochemical testing. The results are as follows Figure 1 As shown, it was found that at 0.5 mA cm -2 , 0.5 mAh cm -2Under the condition of , the battery can maintain a cycle life of 920 h, and the average CE is stable at 99.6%. Figure 2 As shown, the Sn||Cu half-cell installed using the above electrolyte has a high capacitance at 1 mA cm -2 , 0.5 mAhcm -2 Under the condition of high temperature, it can stably cycle for more than 300 times, and the average CE is stable at 99.4%.

[0037] Example 2 The preparation method of 0.5 M acetic acid solution used in the embodiment is: First add 4.8571 mL of deionized water, then add 0.1429 mL of pure acetic acid and stir evenly.

[0038] The method for preparing the aqueous tin ion battery electrolyte in this embodiment is different from that in Example 1 only in that the concentration of the acetic acid solution added to the glass bottle in Example 2 is changed to 0.5 M. The rest are the same, and finally 0.5 M CH3COOH+0.5 M Sn(CH3COO)2+NH4OAc+TGA+CS is obtained by mixing.

[0039] The above electrolyte formulation was installed as a Sn||Cu half-cell for electrochemical testing. The results are as follows Figure 3 As shown, the results show that the battery still has a coulombic efficiency of more than 98% at the beginning. During the cycle, the battery can cycle stably for 360 cycles, and the average CE is stable at 99.6%.

[0040] Example 3 The preparation method of 2 M acetic acid solution used in the embodiment is: First add 4.4286 mL of deionized water, then add 0.5714 mL of pure acetic acid and stir evenly.

[0041] The method for preparing the aqueous tin ion battery electrolyte in this embodiment is different from that in Example 1 only in that the concentration of the acetic acid solution added to the glass bottle in Example 2 is changed to 2 M. The rest are the same, and finally 2 M CH3COOH+0.5 MSn(CH3COO)2+NH4OAc+TGA+CS are obtained by mixing.

[0042] The above electrolyte formulation was installed as a Sn||Cu half-cell for electrochemical testing. The results are as follows Figure 4 As shown, the results showed that under different concentrations of acetic acid, the initial coulombic efficiency was 98%, and the battery operated stably during the cycle.

[0043] Comparative Example 1 The preparation method of 1 M sulfuric acid solution used in this example is: First add 4.7283 mL of deionized water, then add 0.2717 mL of concentrated sulfuric acid and stir well.

[0044] Preparation method of the electrolyte of the aqueous tin ion battery in this embodiment: Take 1 mL of 1 M sulfuric acid solution and add it to a glass bottle. Then add 0.1074 g of tin sulfate and mix well to obtain 1 MH2SO4 + 0.5 M SnSO4.

[0045] The above electrolyte formulation was installed as a Sn||Cu half-cell for electrochemical testing. The results are as follows Figure 5 As shown in the results, it was found that the initial coulombic efficiency of the electrolyte was significantly lower than that of the electrolyte configured in the present invention, and the cycle life was not long. The battery had obvious irreversible reactions after less than 50 cycles. −2 The cycle life of the battery is shorter at a current density of Figure 6 ).

[0046] Comparative Example 2 The preparation method of the electrolyte in this example is the same as that in Example 1, except that the additives in Example 1 are not added to obtain 1 MCH3COOH+0.5 M Sn(CH3COO)2.

[0047] The above electrolyte formulation was installed as a Sn||Cu half-cell for electrochemical testing. The results are as follows Figure 7 As shown, it was found that at 0.5 mA cm -2 , 0.5 mAh cm -2 Under the conditions of , the battery can maintain a longer cycle life, but the cycle life is shorter than that of Example 1, and the CE is not stable enough.

[0048] Comparative Example 3 The preparation method of the electrolyte in this example is the same as that in Example 2, except that the additives in Example 2 are not added to obtain 0.5 MCH3COOH+0.5 M Sn(CH3COO)2.

[0049] The above electrolyte formulation was installed as a Sn||Cu half-cell for electrochemical testing. The results are as follows Figure 8 As shown, it was found that at 0.5 mA cm -2 , 0.5 mAh cm -2 Under the conditions of Example 2, the cycle life of the battery is shorter than that of Example 2.

[0050] Comparative Example 4 The preparation method of the electrolyte in this example is the same as that in Example 3, except that the additives in Example 3 are not added to obtain 2 MCH3COOH+0.5 M Sn(CH3COO)2.

[0051] The above electrolyte formulation was installed as a Sn||Cu half-cell for electrochemical testing. The results are as follows Figure 9 As shown, it was found that at 0.5 mA cm -2 , 0.5 mAh cm -2 Under the conditions of , the cycle life of the battery is significantly shorter than that of the electrolyte with composite additives.

[0052] By comparing the above examples with the comparative examples, it can be clearly found that the electrolyte containing the composite additive can significantly improve the cycle life of the battery in the tin-copper asymmetric battery.

[0053] Example 1 and Comparative Example 1 were placed in glass bottles and placed under sealed conditions for 30 days. Figure 10 It can be found that after one month of storage, the electrolyte of Example 1 is still clear and transparent, while the electrolyte of Comparative Example 1 is obviously turbid.

[0054] The electrode surface after cycling photographed by an optical microscope clearly shows that the corrosion phenomenon of Comparative Example 1 is significantly more serious ( Figure 11 ), which proves that the present invention has a significant effect of slowing down the corrosion of the electrode.

[0055] The above is only a preferred embodiment of the present invention and is not intended to be a formal limitation on the technical solution of the present invention. Any simple modification, equivalence, or variation of the above embodiment based on the technical essence of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A method for preparing an aqueous tin ion battery electrolyte, characterized in that: The following steps are involved: (1) adding a tin salt to the acetic acid solution prepared in step (1), stirring and mixing thoroughly to obtain an acidic tin salt solution; (2) Ammonium acetate, thioglycolic acid solution, and deacetylated chitosan solution are sequentially added to the acidic tin salt solution of step (1) and stirred evenly to obtain a tin ion battery electrolyte.

2. The method for preparing an aqueous tin ion battery electrolyte according to claim 1, wherein: The concentration of the acetic acid solution is 0.5-18 M, and the pH of the acidic tin salt solution is controlled to be 1-2.

3. The method for preparing an aqueous tin ion battery electrolyte according to claim 1, wherein: The tin salt includes one or more of tin acetate, tin sulfate, tin chloride, tin fluoborate, tin pyrophosphate, tin oxalate or tin trifluoromethanesulfonate; the concentration of the tin salt is 0.5-2 M.

4. The method for preparing an aqueous tin ion battery electrolyte according to claim 1, wherein: The mass fraction of ammonium acetate is 1-3%, preferably 1-2%.

5. The method for preparing an aqueous tin ion battery electrolyte according to claim 1, wherein: The mass fraction of the thioglycolic acid solution is 1-5%, preferably 1-3%.

6. The method for preparing an aqueous tin ion battery electrolyte according to claim 1, wherein: The mass fraction of the chitosan solution is 0.5-2%, preferably 0.5-1%.

7. An aqueous tin ion battery electrolyte, characterized in that: The electrolyte prepared by the method according to any one of claims 1 to 6 mainly uses water as the main solvent, the concentration of tin ions as the effective active ingredient in the electrolyte is 0.5-2 M, the pH of the electrolyte is controlled in the range of 1-2, and the electrolyte is clear and transparent.

8. A tin asymmetric battery, characterized in that The invention comprises the aqueous tin ion battery electrolyte according to claim 7.

9. A tin ion electrochemical energy storage device using the electrolyte according to claim 7, characterized in that: The tin ion electrochemical energy storage device is an aqueous secondary battery containing tin ions.

10. A tin ion electrochemical energy storage device using the electrolyte according to claim 7, characterized in that: The tin ion electrochemical energy storage device is an aqueous battery capacitor containing tin ions.

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