A water-based tin metal battery electrolyte containing a metal sulfate additive, a preparation method and application thereof

Abstract

This invention relates to the field of aqueous metal battery technology, specifically to an aqueous tin metal battery electrolyte containing metal sulfate additives, its preparation method, and its application. The electrolyte is based on an alkaline electrolyte (such as KOH) and soluble tin salts (such as SnSO4, SnCl2), with added metal sulfates such as Li2SO4, ZnSO4, K2SO4, MnSO4, or Na2SO4 as additives at a concentration of 0.01 mol / L to 0.5 mol / L. The metal cations preferentially adsorb onto the surface of the metal anode to form an electrostatic shielding layer, regulating metal ion deposition behavior, inhibiting the formation of "dead tin," and significantly improving the battery's cycle stability and coulombic efficiency.

Description

Technical Field

[0001] This invention relates to the field of aqueous metal battery technology, specifically to an aqueous tin metal battery electrolyte containing metal sulfate additives, its preparation method, and its application. Background Technology

[0002] The ever-increasing demand for energy and the worsening environmental pollution have jointly driven the research and development of renewable clean energy and large-scale energy storage technologies. Lithium-ion batteries (LIBs) have dominated the portable electronic device and electric vehicle markets for decades due to their high energy density and stable performance; however, their inherent drawbacks, such as the uneven geographical distribution of lithium resources, high cost, and safety hazards posed by organic electrolytes, have limited their application in the field of large-scale energy storage.

[0003] Against this backdrop, aqueous electrolytes have become a highly attractive alternative in the field of large-scale energy storage due to their inherent safety (non-flammable and non-explosive), environmental friendliness, high ionic conductivity, ease of preparation, and low cost. Among these, electrolytes based on multivalent metal ions (such as Zn) are particularly promising. 2+ Sn 2+ Al 3+ Aqueous metal batteries (such as those with high theoretical specific capacity and low electrode potential) have attracted much attention due to the advantages of metal anodes.

[0004] However, existing aqueous metal batteries still face severe challenges. Taking aqueous zinc metal batteries as an example, the uncontrollable dendrite growth, severe hydrogen evolution corrosion, and the resulting interface instability and capacity decay of the zinc anode during cycling remain the core problems restricting their practical application. For alkaline aqueous tin metal batteries, although the tin anode has advantages such as a body-centered tetragonal crystal structure (isotropic morphology, tending to form "tin mounds" rather than dendrites) and a high hydrogen evolution overpotential, it still faces two major bottleneck problems: "dead tin" and "Helmholtz layer repulsion." On the one hand, the polyhedral tin grains deposited on the surface of the tin anode are prone to detachment, forming "dead tin," resulting in a coulombic efficiency of less than 80% and a cycle life of less than 20 hours. On the other hand, the negatively charged tin oxide anions (such as Sn(OH)3) in the Helmholtz layer at the tin anode interface... - The repulsion significantly raises the reduction energy barrier, resulting in slowed deposition kinetics. Summary of the Invention

[0005] To address the shortcomings of the existing technology, the present invention aims to provide an aqueous tin metal battery electrolyte containing metal sulfate additives, its preparation method, and its application. By introducing metal sulfates such as Li2SO4, ZnSO4, K2SO4, MnSO4, and Na2SO4, the formation of dead tin is suppressed and the repulsion effect of the Helmholtz layer is alleviated, thereby improving the cycle stability and coulombic efficiency of the battery.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: An aqueous tin metal battery electrolyte containing a metal sulfate additive, the electrolyte comprising an electrolyte, a metal salt, deionized water, and a metal sulfate additive.

[0007] The metal sulfate additive includes any one of lithium sulfate (Li2SO4), zinc sulfate (ZnSO4), potassium sulfate (K2SO4), manganese sulfate (MnSO4), and sodium sulfate (Na2SO4).

[0008] Metal sulfates such as Li₂SO₄, ZnSO₄, K₂SO₄, MnSO₄, and Na₂SO₄ are introduced as electrolyte additives to improve the reversibility of aqueous metal batteries. For example, tin anodes typically suffer from dead tin due to the repulsive effect of the Helmholtz layer, but in this system, Li₂SO₄... + Zn 2+ K + Mn 2+ and Na + It will preferentially accumulate at the interface of the tin anode, affecting Sn(OH)3. - The ions form a strong electrostatic shield, guiding them to deposit in a smoother region of the negative electrode, thus effectively and uniformly depositing tin metal.

[0009] In a preferred embodiment of the present invention, the concentration of the metal sulfate additive is 0.01 mol / L to 1 mol / L.

[0010] In a preferred embodiment of the present invention, it is further preferred that the concentration of the metal sulfate additive is 0.05 mol / L-0.5 mol / L.

[0011] In a preferred embodiment of the present invention, the electrolyte is potassium hydroxide (KOH) with a concentration of 1 mol / L to 5 mol / L.

[0012] In a preferred embodiment of the present invention, the metal salt is a soluble tin salt, which is stannous sulfate or stannous chloride, with a concentration of 0.05 mol / L to 0.5 mol / L.

[0013] The preparation method of the aqueous tin metal battery electrolyte containing metal sulfate additives includes the following steps: dissolving the electrolyte, metal tin salt and metal sulfate additives in deionized water in sequence and mixing them to obtain the aqueous tin metal battery electrolyte containing metal sulfate additives.

[0014] The present invention relates to the application of the aqueous tin metal battery electrolyte containing metal sulfate additives in the negative electrode of an aqueous tin metal battery.

[0015] Compared with the prior art, the beneficial effects of the present invention are: This invention uses metal sulfates as electrolyte additives to suppress dead tin and Helmholtz layer formation, thereby improving cycle stability; metal cations (such as Li) + Zn 2+ K + Mn 2+ Na + Sn(OH) can preferentially adsorb onto the surface of the metal negative electrode, forming an electrostatic shielding layer and stabilizing Sn(OH). 3- It also reduces side reactions and inhibits the formation of dead tin. Experimental results show that after introducing metal sulfate additives, the metal anode deposition layer is more dense and smooth, the battery cycle life is significantly extended, and the coulombic efficiency is stabilized at a high level, making it suitable for high-performance aqueous tin metal battery systems. Attached Figure Description

[0016] Figure 1 SEM images of tin electrodes under different electrolyte systems and areal capacities (test conditions: current density 10 mA·cm). -2 ), where a is the KOH / SnSO4 electrolyte at 10 mA·cm⁻¹ -2 The current density, 10 mA·h·cm -2 SEM images after testing under the areal capacity condition; b is the SEM image after testing in KOH / SnSO4 electrolyte at 20 mA·h·cm⁻¹. -2 SEM images after testing under the areal capacity condition; c represents the KOH / SnSO4 / ZnSO4 electrolyte at 10 mA·cm⁻¹. -2 Current density, 10 mA·h·cm -2 SEM images after testing under the areal capacity condition; d represents the KOH / SnSO4 / ZnSO4 electrolyte at 20 mA·h·cm⁻¹. -2 SEM images after testing under the areal capacity condition.

[0017] Figure 2 Long-term cycle voltage curves of tin-symmetric batteries under different electrolyte systems (test conditions: current density 10 mA·cm⁻¹) -2 0.5mAh·cm -2 (The inset a shows the voltage amplification curve for the 100th cycle, comparing the voltage at 10 mA·cm⁻¹ between two electrolytes: KOH / SnSO₄ / ZnSO₄ (dashed) and KOH / SnSO₄ (solid line).) -2 0.5 mA·h·cm -2a) Voltage curve under single-cycle conditions; b) Voltage amplification curve at the 800th cycle; c) Voltage amplification curves of KOH / SnSO4 / ZnSO4 electrolyte at different long cycle numbers, including voltage curves at the 2000th, 1000th, and 5000th cycles.

[0018] Figure 3 Hydrogen evolution rate curves of tin batteries under different electrolyte systems (test conditions: current density 10 mA·cm⁻¹) -2 5 mAh·cm -2 ). Detailed Implementation

[0019] The following detailed description, in conjunction with embodiments of the present invention and accompanying drawings, provides a clear and complete illustration of the technical solutions in these embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0020] It should be noted that all technical terms used in this invention are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased from the market or prepared by existing methods.

[0021] The purpose of this invention is to provide an aqueous tin metal battery electrolyte containing metal sulfate additives and its application, characterized in that the electrolyte comprises an electrolyte, a tin metal salt, deionized water and a metal sulfate additive.

[0022] In this invention, the concentration of the metal sulfate additive is preferably from 0.01 mol / L to 0.5 mol / L, more preferably from 0.05 mol / L to 0.5 mol / L. Concentrations that are too high or too low will affect battery performance: too low a concentration will result in insignificant regulatory effects; too high a concentration may cause increased electrolyte viscosity, impeded ion migration, or even induce side reactions.

[0023] In this invention, the electrolyte is KOH, preferably with a concentration of 1 mol / L to 5 mol / L, used to maintain the alkaline environment of the electrolyte and inhibit the hydrolysis of metal ions.

[0024] In this invention, the metal salt is a soluble tin salt, such as stannous sulfate (SnSO4) or stannous chloride (SnCl2), with a preferred concentration of 0.05 mol / L to 0.5 mol / L, used to provide electrochemically active ions.

[0025] The present invention also provides the application of the metal sulfate modified aqueous tin metal battery electrolyte described in the above technical solution in aqueous tin metal batteries.

[0026] Example 1 (containing ZnSO4 additive) Prepare 50 mL of electrolyte: Weigh 1.438 g ZnSO4·7H2O and dissolve it in 10 mL of deionized water, stirring until dissolved; add 8.416 g KOH and 1.074 g SnSO4, and continue stirring until completely dissolved; transfer to a 50 mL volumetric flask and dilute to volume with deionized water to obtain an electrolyte containing 0.1 mol / L ZnSO4 of 3 mol / L KOH + 0.1 mol / L SnSO4.

[0027] Example 2 (containing Li2SO4 additive) Referring to Example 1, the additive was replaced with an equimolar amount of Li2SO4 to prepare an aqueous tin metal battery electrolyte containing 0.1 mol / L Li2SO4.

[0028] Example 3 (containing K2SO4 additive) Referring to Example 1, the additive was replaced with an equimolar amount of K2SO4 to prepare an alkaline aqueous tin metal battery electrolyte containing 0.1 mol / L K2SO4.

[0029] Example 4 (containing MnSO4 additive) Referring to Example 1, the additive was replaced with an equimolar amount of MnSO4 to prepare an aqueous tin metal battery electrolyte containing 0.1 mol / L MnSO4.

[0030] Example 5 (containing Na2SO4 additive) Referring to Example 1, the additive was replaced with an equimolar amount of Na2SO4 to prepare an aqueous tin metal battery electrolyte containing 0.1 mol / L Na2SO4.

[0031] Example 6 (Comparison with other types of additives – carboxylates) To verify the optimality of the metal sulfate additive, a comparative electrolyte containing 0.1 mol / L sodium acetate (CH3COONa) was prepared: 0.410 g of CH3COONa was added to a basic system of 3 mol / L KOH + 0.1 mol / L SnSO4, and the solution was dissolved and brought to a final volume of 50 mL.

[0032] Example 7 (Comparison with other types of additives - halides) Prepare a comparative electrolyte containing 0.1 mol / L zinc chloride (ZnCl2): Add 0.681 g ZnCl2 to a basic system of 3 mol / L KOH + 0.1 mol / L SnSO4, and dissolve and bring the volume to 50 mL.

[0033] Comparative Example 1 (No Additives) Prepare 50 mL of basic electrolyte: Dissolve 8.416 g KOH and 1.074 g SnSO4 in deionized water, stir until completely dissolved, transfer to a volumetric flask and make up to volume to obtain a 3 mol / L KOH and 0.1 mol / L SnSO4 electrolyte without any additives.

[0034] Example 8 (Battery Assembly and Symmetrical Battery Testing) Using the electrolytes of Examples 1-7 and Comparative Example 1, respectively, symmetrical cells (such as Sn / / Sn) or half-cells (such as Sn / / Cu) were assembled with tin foil as the symmetrical electrode and glass fiber as the separator, and cycle performance and coulombic efficiency were tested.

[0035] Results Analysis Figure 1 SEM images of tin electrodes under different electrolyte systems and areal capacities (test conditions: current density 10 mA·cm). -2 ), where a is the KOH / SnSO4 electrolyte at 10 mA·cm⁻¹ -2 The current density, 10 mA·h·cm -2 SEM images after testing under the areal capacity condition; b is the SEM image after testing in KOH / SnSO4 electrolyte at 20 mA·h·cm⁻¹. -2 SEM images after testing under the areal capacity condition; c represents the KOH / SnSO4 / ZnSO4 electrolyte at 10 mA·cm⁻¹. -2 Current density, 10 mA·h·cm -2 SEM images after testing under the areal capacity condition; d represents the KOH / SnSO4 / ZnSO4 electrolyte at 20 mA·h·cm⁻¹. -2 SEM images after testing under the areal capacity condition.

[0036] Test conditions: Current density 10 mA·cm -2 The scale bar is 50 μm, and the tin electrode deposition morphology of the additive-containing and additive-free systems is compared.

[0037] Systems containing metal sulfate additives (such as ZnSO4, Li2SO4, etc.): The tin deposition layer exhibits a uniform, dense, and flat morphology, with no obvious grain agglomeration or shedding. The deposition layer is tightly bonded to the electrode substrate, and no irregular protrusions were observed.

[0038] Additive-free system (KOH / SnSO4): The tin deposition layer exhibits irregular agglomeration, uneven grain size, and loosely packed particles in some areas, with obvious gaps and detachment traces, consistent with the morphological characteristics of "dead tin" formation.

[0039] At different areal capacities, the deposition morphology of the additive system was consistent, while the agglomeration phenomenon of the additive-free system became more severe with the increase of areal capacities.

[0040] Metal sulfate additives can regulate Sn(OH)3 - The deposition behavior of ions guides them to be deposited uniformly in the smooth region of the negative electrode, avoiding disordered growth and shedding of grains, thereby forming a dense and stable deposition layer, providing structural support for the long cycle life of the battery.

[0041] Figure 2 Long-term cycle voltage curves of tin-symmetric batteries under different electrolyte systems (test conditions: current density 10 mA·cm⁻¹) -2 Capacity 0.5 mAh·cm -2 (The inset a shows the voltage amplification curve for the 100th cycle, comparing the voltage at 10 mA·cm⁻¹ between two electrolytes: KOH / SnSO₄ / ZnSO₄ (dashed) and KOH / SnSO₄ (solid line).) -2 0.5 mA·h·cm -2 The first graph shows the voltage difference at the beginning of the cycle under the given conditions; the second graph shows the voltage amplification curve at the 800th cycle, comparing the single-cycle voltage behavior of the two electrolytes under the same test conditions to illustrate the changes in voltage stability after long cycles; the third graph shows the voltage amplification curves of the KOH / SnSO4 / ZnSO4 electrolyte at different long cycle numbers, including the voltage curves at the 2000th, 1000th, and 5000th cycles, with the test condition remaining at 10 mA·cm. -2 0.5 mA·h·cm -2 The study focuses on demonstrating the stability of the voltage plateau of this electrolyte during extremely long cycling, with the test conditions being a current density of 10 mA·cm⁻¹. -2 Capacity 0.5 mAh·cm -2 The electrode system is a Sn / / Sn symmetric cell.

[0042] The system containing metal sulfate additives (taking ZnSO4 as an example, the curve is labeled "KOH / SnSO4+ZnSO4"): the voltage curve remained stable for a long time without significant fluctuations or sudden drops, the cycle life was significantly extended to more than 2500 h, and no signs of failure were observed.

[0043] Additive-free system (curve labeled "KOH / SnSO4"): The voltage fluctuation is small in the early stage of cycling, but the voltage fluctuates drastically and drops rapidly in a short period of time (far below 2500 h), and the battery fails quickly, which is consistent with the characteristic of "additive-free tin battery cycle life less than 20 hours" in the background technology.

[0044] The voltage curves of other metal sulfate additive systems (Li2SO4, K2SO4, etc.) also showed good stability, and their cycle life was significantly better than that of the additive-free system, only slightly lower than that of the ZnSO4 additive system.

[0045] Metal sulfate additives can stabilize the electrode interface by forming an electrostatic shielding layer and suppress the formation of "dead tin", thereby significantly improving the cycle stability of the battery; among them, ZnSO4 additives have the best effect and the most significant improvement on voltage stability.

[0046] Figure 3 shows the hydrogen evolution rate curves of tin batteries under different electrolyte systems; Test conditions: Current density 10 mA·cm -2 5 mAh·cm -2 The intensity of the hydrogen evolution side reaction is reflected by the peak value and trend of the curve.

[0047] The system containing ZnSO4 additive (curve labeled "KOH / SnSO4+ZnSO4") shows a significant decrease in the peak value of the hydrogen evolution rate curve, which remains at a low level throughout the cycle without a significant upward trend, indicating that the hydrogen evolution side reaction is effectively suppressed.

[0048] Additive-free system (curve labeled "KOH / SnSO4"): The hydrogen evolution rate curve has a high peak value and continues to rise with the extension of cycle time, indicating that the hydrogen evolution corrosion on the tin anode surface is severe and a large amount of hydrogen gas is generated, leading to the destruction of the electrode interface.

[0049] The hydrogen evolution rate of other metal sulfate additive systems was lower than that of the additive-free system, with ZnSO4 and Li2SO4 showing the most significant inhibitory effects.

[0050] Metal sulfate additives reduce the active sites at the electrode interface by adsorbing metal cations on the negative electrode surface, thereby reducing the water reduction reaction, inhibiting side reactions, avoiding electrode corrosion and capacity decay, and improving the coulombic efficiency of the battery.

[0051] Table 1 shows the performance comparison between Examples 1-7 and Comparative Example 1. As shown in Table 1, in the alkaline aqueous tin metal battery system, the test results show that after introducing metal sulfate additives (especially ZnSO4), the cycle life of the tin symmetric battery is significantly extended to over 2500 h, and the voltage curve is stable, while the system without additives fails rapidly. SEM morphology shows that the tin deposition in the additive system is uniform and dense, while the system without additives exhibits irregular agglomeration.

[0052] Compared to other types of additives (such as carboxylates and halides), metal sulfate additives exhibit significant advantages in cycle life, coulombic efficiency, and side reaction suppression. Carboxylate additives offer limited performance improvement due to the hindering effect of organic groups on deposition kinetics; while halide additives may limit long-term stability due to halide ion corrosion of the electrode. This further highlights the superiority of metal sulfates as additives for aqueous tin-based battery electrolytes.

[0053] The above results indicate that metal sulfate additives, especially ZnSO4, are well-suited for alkaline aqueous tin metal batteries and can significantly improve the battery's electrochemical performance and cycle stability.

[0054] This invention uses metal sulfates as electrolyte additives to inhibit the formation of dead tin, alleviate the Helmholtz layer repulsion effect, and improve cycle stability; metal cations (such as Li) + Zn 2+ K + Mn 2+ Na + Sn(OH) can preferentially adsorb onto the surface of the metal negative electrode, forming an electrostatic shielding layer and stabilizing Sn(OH). 3- It also reduces side reactions and inhibits the formation of dead tin. Experimental results show that after introducing metal sulfate additives, the metal anode deposition layer is more dense and smooth, the battery cycle life is significantly extended, and the coulombic efficiency is stabilized at a high level, making it suitable for high-performance aqueous tin metal battery systems.

[0055] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described here to avoid redundancy. Although preferred embodiments of the invention have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this invention.

[0056] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. An aqueous tin metal battery electrolyte containing metal sulfate additives, characterized in that, The electrolyte comprises an electrolyte, a soluble tin salt, water, and a metal sulfate additive; The metal sulfate additive is any one of lithium sulfate, zinc sulfate, potassium sulfate, manganese sulfate, and sodium sulfate.

2. The aqueous tin metal battery electrolyte containing metal sulfate additives according to claim 1, characterized in that, The concentration of the metal sulfate additive is 0.01 mol / L-0.5 mol / L.

3. The aqueous tin metal battery electrolyte containing metal sulfate additives according to claim 1, characterized in that, The electrolyte is potassium hydroxide with a concentration of 1 mol / L to 5 mol / L.

4. The aqueous tin metal battery electrolyte containing metal sulfate additives according to claim 1, characterized in that, The metal salt is a soluble tin salt, specifically stannous sulfate or stannous chloride.

5. The aqueous tin metal battery electrolyte containing metal sulfate additives according to claim 4, characterized in that, The concentration of metallic tin salt is 0.05 mol / L-0.5 mol / L.

6. The method for preparing the aqueous tin metal battery electrolyte containing metal sulfate additives according to claim 1, characterized in that, The process includes the following steps: dissolving the electrolyte, tin salt, and metal sulfate additive sequentially in deionized water and mixing them to obtain an aqueous tin metal battery electrolyte containing metal sulfate additive.

7. The application of the aqueous tin metal battery electrolyte containing metal sulfate additives according to claim 1 in the negative electrode of an aqueous tin metal battery.

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