Long-acting composite additive, aqueous electrolyte and zinc-based battery

Abstract

The invention belongs to the technical field of zinc-based batteries, and particularly relates to a long-acting composite additive, an aqueous electrolyte and a zinc-based battery. The long-acting composite additive provided by the invention comprises a subject additive (as shown in a formula 1) and an object additive (as shown in a formula 2), the guest additive can be directionally arranged in the aqueous electrolyte to form a hydrophilic shell of the micelle, and the host additive is coated in a hydrophobic core cavity, so that uniform dispersion and stable coexistence are realized, and the micelle structure realizes long-acting stable release of the host additive and ensures a lasting and stable interface modification effect; dendritic crystal growth and side reactions of hydrogen evolution and corrosion are inhibited, and the cycle life, coulombic efficiency and rate capability of the zinc-based battery are improved. Formula 1 and Formula 2.

Description

Technical Field

[0001] This invention belongs to the field of zinc-based battery technology, specifically relating to a long-lasting composite additive, an aqueous electrolyte, and a zinc-based battery. Background Technology

[0002] In aqueous zinc-based battery systems, zinc metal anodes are considered ideal anode materials due to their high specific capacity, abundant resources, and intrinsic safety, and have broad application prospects in large-scale energy storage. However, the development of this system is severely constrained by the zinc anode / electrolyte interface problem: on the one hand, uneven deposition of zinc ions at the interface can easily lead to dendrite growth, which may cause battery short circuits; on the other hand, side reactions such as hydrogen evolution and corrosion caused by water molecules will continuously consume active zinc and electrolyte, significantly deteriorating the battery's cycle life and coulombic efficiency.

[0003] To stabilize the zinc anode interface, electrolyte functionalization additives have become a research hotspot due to their simplicity and efficiency. Introducing a single additive can, to some extent, modulate the zinc ion solvation structure or interfacial adsorption behavior. However, the complexity and multifaceted nature of zinc anode interface problems make it difficult for single-component additives to achieve comprehensive and long-term stabilization. For example, additives focused on optimizing deposition morphology may not effectively prevent water molecule erosion, while additives that simply suppress side reactions may negatively impact ion migration. More importantly, most single additives are continuously consumed or become ineffective during cycling, failing to provide durable interfacial protection and potentially introducing new compatibility issues due to their singular function.

[0004] To overcome the limitations of single additives, researchers have begun exploring composite additive systems, aiming to achieve comprehensive regulation of the interfacial microenvironment through the synergistic effects of various components. However, traditional composite additives suffer from difficulties in coordinating solubility, dispersion stability, and intermolecular interactions in electrolytes, leading to component segregation or functional interference. Secondly, the adsorption competition among components at the electrode interface cannot be effectively controlled, resulting in a loose and functionally uneven interfacial modification layer, making it difficult to form a dense and stable protective layer. Most importantly, traditional composite methods cannot achieve controlled release of additives, and their rapid consumption in the early stages of cycling makes long-term protective functions unsustainable. In summary, the shortcomings of existing composite additives in terms of dispersion uniformity, functional synergy, and long-term effectiveness limit their practical applications. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a long-lasting composite additive, an aqueous electrolyte, and a zinc-based battery. In this invention, the guest additive in the long-lasting composite additive can be oriented to form a hydrophilic shell of micelles in the aqueous electrolyte, while the main additive is encapsulated in the hydrophobic core cavity, thereby achieving uniform dispersion and stable coexistence. This micellar structure enables the long-lasting and stable release of the main additive, ensuring a durable and stable interface modification effect, inhibiting dendrite growth and side reactions such as hydrogen evolution and corrosion, and improving the cycle life, coulombic efficiency, and rate performance of the zinc-based battery.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a long-acting compound additive, comprising a main additive and a guest additive; The structure of the main additive is shown in Formula 1: Formula 1, The structure of the guest additive is as shown in Formula 2: Formula 2; The R1 includes at least one of hydrogen, C1-C3 alkyl, methylthio, cyano, sulfonic acid, halogen, halogen-substituted C1-C3 alkyl, halogen-substituted methylthio, and halogen-substituted sulfonic acid. The R2 includes at least one of sulfonic acid group, carboxyl group, hydroxyl group, amino group and glucosyl group.

[0007] Preferably, the molar ratio of the main additive to the guest additive is 1:(0.5~5).

[0008] Preferably, the main additive is N-trifluoromethylthiosaccharin.

[0009] Preferably, the guest additive is lauryl glucoside.

[0010] The present invention also provides an aqueous electrolyte comprising water, electrolyte salt and additives, wherein the additives are the long-acting composite additives described in the above technical solution; in the long-acting composite additives, the guest additives encapsulate the host additives to form micelle structures.

[0011] Preferably, the total mass of the long-acting compound additive accounts for 0.001 to 5 wt.% of the total mass of the electrolyte salt and water.

[0012] Preferably, the electrolyte salt is a zinc salt; the zinc salt includes at least one of zinc sulfate, zinc trifluoromethanesulfonate, zinc perchlorate, zinc chloride, zinc nitrate, zinc acetate, and zinc difluorosulfonamide.

[0013] Preferably, the molar concentration of the electrolyte salt in the aqueous electrolyte is 0.1~3 mol / L.

[0014] The present invention also provides a zinc-based battery, comprising an electrolyte, a positive electrode, a negative electrode, and a separator, wherein the electrolyte contains the long-lasting composite additive described in the above technical solution, or the electrolyte is the aqueous electrolyte described in the above technical solution.

[0015] Preferably, the zinc-based battery is a zinc-ion battery, a zinc-air battery, or a zinc-based flow battery.

[0016] This invention provides a long-acting compound additive, comprising a main additive and a guest additive; The structure of the main additive is shown in Formula 1: Formula 1, The structure of the guest additive is as shown in Formula 2: Formula 2; The R1 includes at least one of hydrogen, C1-C3 alkyl, methylthio, cyano, sulfonic acid, halogen, halogen-substituted C1-C3 alkyl, halogen-substituted methylthio, and halogen-substituted sulfonic acid. The R2 includes at least one of sulfonic acid group, carboxyl group, hydroxyl group, amino group and glucosyl group.

[0017] In this invention, the host additive and guest additive spontaneously assemble into structurally stable micelles in an aqueous electrolyte through intermolecular forces. The guest additive aligns in the aqueous solution with its R2 end facing outwards and the other end converging inwards, forming micelles with a hydrophilic shell and a hydrophobic core cavity. The host additive is encapsulated within the hydrophobic core cavity, thus achieving uniform molecular-level dispersion and stable coexistence of the composite additives in solution. Based on this unique micelle structure, the decomposition of the additives in an electric field environment can be delayed, achieving long-term stable release of the host additive. During battery cycling, the micelles respond to changes in the interfacial environment, dynamically and controllably releasing the active component (host additive) within its core cavity slowly, ensuring a durable and stable interfacial modification effect. The main additive in this mechanism can form a dense and stable solid electrolyte interphase (SEI) film on the negative electrode surface, effectively regulating the zinc ion solvation structure (altering the environment around zinc ions to include not only water molecules but also micelles, making them easier to desolvate) and guiding their easier and more uniform deposition. This simultaneously suppresses dendrite growth and side reactions such as hydrogen evolution and corrosion, significantly improving the cycle life, coulombic efficiency, and rate performance of zinc-based batteries. Furthermore, the preparation process of this long-lasting composite additive is simple and inexpensive, providing a reliable technical path for the industrialization of high-performance, long-life aqueous zinc-based batteries. Attached Figure Description

[0018] Figure 1 Comparative graph showing the long-cycle performance test comparison of Zn||I2 button batteries assembled with aqueous electrolytes in Comparative Example 1 and Example 1; Figure 2 The images show the surface morphology of the zinc anode in the Zn||I2 coin cells assembled with aqueous electrolytes in Comparative Example 1 and Example 1, where a represents Comparative Example 1 and b represents Example 1. Detailed Implementation

[0019] This invention provides a long-acting compound additive, comprising a main additive and a guest additive; The structure of the main additive is shown in Formula 1: Formula 1, The structure of the guest additive is as shown in Formula 2: Formula 2; The R1 includes at least one of hydrogen, C1-C3 alkyl, methylthio, cyano, sulfonic acid, halogen, halogen-substituted C1-C3 alkyl, halogen-substituted methylthio, and halogen-substituted sulfonic acid. The R2 includes at least one of sulfonic acid group, carboxyl group, hydroxyl group, amino group and glucosyl group.

[0020] Unless otherwise specified, the present invention does not have special requirements on the source of raw materials used, and commercially available products well known to those skilled in the art can be used.

[0021] In one embodiment, R1 includes at least one of hydrogen, C1-C3 alkyl, methylthio, cyano, sulfonic acid, halogen, halogen-substituted C1-C3 alkyl, halogen-substituted methylthio, and halogen-substituted sulfonic acid, with a specific embodiment being a halogen-substituted sulfonic acid; the halogen-substituted sulfonic acid is -SF3. The main additive can form a dense and stable solid electrolyte interphase (SEI) film on the negative electrode surface, suppressing dendrite growth and side reactions such as hydrogen evolution and corrosion, significantly improving the cycle life, coulombic efficiency, and rate performance of zinc-based batteries.

[0022] In one embodiment, R2 includes at least one of sulfonic acid group, carboxyl group, hydroxyl group, amino group and glucosyl group, and in a specific embodiment it is glucosyl group.

[0023] The host additive and guest additive described in this invention can spontaneously form micelle structures in an aqueous electrolyte. The guest additive will oriented in the aqueous system with the R2 end facing outward and the alkyl end converging inward, forming micelles with a hydrophilic shell and a hydrophobic core cavity, while the host additive is encapsulated inside the hydrophobic core cavity, thereby achieving molecular-level uniform dispersion and stable coexistence of the composite additive in the solution.

[0024] In this invention, the main additive is gradually consumed as the battery operates; the guest additive can improve the solubility and dispersibility of the main additive in the aqueous electrolyte and prolong the action time of the main additive in the electrolyte.

[0025] In this embodiment of the invention, the main additive is N-trifluoromethylthiosaccharin; the guest additive is lauryl glucoside.

[0026] In one embodiment, the molar ratio of the main additive to the guest additive is 1:(0.5~5), and in specific embodiments it is 1:1 or 1:2.

[0027] The long-lasting composite additive provided by this invention comprises two components: a host additive and a guest additive. This composite additive system, through its self-assembly into a micelle structure in the electrolyte, effectively encapsulates and controls the release of the host additive, slowing down its consumption and thus achieving a long-lasting and stable interface modification effect. In zinc-based batteries, batteries using this additive exhibit significant advantages in long-cycle stability, high-rate charge-discharge capability, and safety, demonstrating enormous potential for industrial application.

[0028] The present invention also provides an aqueous electrolyte comprising water, electrolyte salt and additives, wherein the additives are the long-acting composite additives described in the above technical solution; in the long-acting composite additives, the guest additives encapsulate the host additives to form micelle structures.

[0029] In one embodiment, the total mass of the long-acting compound additive accounts for 0.001 to 5 wt.% of the total mass of the electrolyte salt and water, and in specific embodiments, it is 0.1 wt.%, 0.5 wt.%, or 1 wt.%.

[0030] In one embodiment, the electrolyte salt is a zinc salt; the zinc salt includes at least one of zinc sulfate, zinc trifluoromethanesulfonate, zinc perchlorate, zinc chloride, zinc nitrate, zinc acetate, and zinc difluorosulfonamide, and in a specific embodiment, zinc sulfate, zinc perchlorate, zinc acetate, zinc trifluoromethanesulfonate, or zinc difluorosulfonamide; the molar concentration of the electrolyte salt in the aqueous electrolyte is 0.1~3 mol / L, and in a specific embodiment, it is 0.5~2 mol / L.

[0031] As one embodiment, the preparation method of the aqueous electrolyte includes the following steps: dissolving zinc salt in water, and then adding a long-lasting composite additive that has been thoroughly stirred. This invention does not impose special limitations on the stirring parameters, as long as the components are mixed uniformly.

[0032] This invention introduces host and guest additives into an aqueous electrolyte, causing them to spontaneously assemble into thermodynamically stable micelle structures in an aqueous environment. This achieves uniform dispersion, long-lasting effect, and synergistic function of the additives. The specific principle is as follows: First, the selected guest additive can spontaneously assemble into micelles in an aqueous electrolyte. The hydrophobic core cavity of the micelle can effectively encapsulate and protect the water-insoluble host additive, while its hydrophilic shell ensures the solubility stability of the entire structure in the electrolyte, providing a structural basis for the controlled storage and targeted release of active ingredients.

[0033] Secondly, the micelle system constructed in this invention possesses a sustained-release function for the main additive. During battery cycling, the micelle structure can continuously and controllably release the main additive encapsulated within the core cavity to the interfacial reaction region through dynamic disassembly and assembly, achieving persistent and stable regulation of the interfacial microenvironment.

[0034] Third, based on the aforementioned slow-release mechanism, the main additive and the guest additive undergo synergistic adsorption at the electrode interface, jointly constructing a dense and stable dynamic protective film. This interface layer can simultaneously regulate the zinc ion flow distribution, optimize deposition behavior, and block water molecule contact, thereby synergistically inhibiting zinc dendrite growth, hydrogen evolution reaction, and interface corrosion, significantly improving the battery's coulombic efficiency, cycle life, and safety performance.

[0035] The present invention also provides a zinc-based battery, comprising an electrolyte, a positive electrode, a negative electrode, and a separator, wherein the electrolyte contains the long-lasting composite additive described in the above technical solution, or the electrolyte is the aqueous electrolyte described in the above technical solution.

[0036] In one embodiment, the zinc-based battery is a zinc-ion battery, a zinc-air battery, or a zinc-based flow battery.

[0037] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, but they should not be construed as limiting the scope of protection of the present invention.

[0038] Example 1 Zinc sulfate electrolyte salt is added to ultrapure water to form an aqueous electrolyte solution. Then, the main additive N-trifluoromethylthiosaccharin and the guest additive lauryl glucoside are mixed in a molar ratio of 1:1 to form a long-acting composite additive. After thorough stirring, 0.1 wt.% of the long-acting composite additive is added to the solution, resulting in an aqueous long-acting composite additive electrolyte solution with stable performance, using zinc sulfate (2 mol / L) as the electrolyte salt.

[0039] Example 2 The other operations are the same as in Example 1, except that zinc perchlorate is used as the zinc salt.

[0040] Example 3 The other operations are the same as in Example 1, except that zinc acetate is used as the zinc salt.

[0041] Example 4 The other operations are the same as in Example 1, except that zinc trifluoromethanesulfonate is used as the zinc salt.

[0042] Example 5 The other operations are the same as in Example 1, except that zinc difluorosulfonamide is used as the zinc salt.

[0043] Example 6 Other operations are the same as in Example 1, except that the main additive N-trifluoromethylthiosaccharin and the guest additive lauryl glucoside are mixed in a molar ratio of 1:2 to form a long-acting compound additive, which accounts for 0.5 wt.% of the total mass of zinc salt and water.

[0044] Example 7 Other operations are the same as in Example 1, except that the main additive N-trifluoromethylthiosaccharin and the guest additive lauryl glucoside are mixed in a molar ratio of 1:2 to form a long-acting compound additive, which accounts for 1 wt.% of the total mass of zinc salt and water.

[0045] Comparative Example 1 Comparative Example 1: Zinc sulfate (2 mol / L) electrolyte salt was added to ultrapure water to form an aqueous electrolyte.

[0046] Performance testing The aqueous electrolytes from Comparative Example 1 and Example 1 were assembled with positive and negative electrodes to form Zn||I2 coin cells. Long-term cycle performance tests were conducted on the full cells to measure the cycle life of different cells. The results are as follows: Figure 1 As shown, the ordinary electrolyte represents Comparative Example 1, and the long-lasting composite additive electrolyte represents Example 1.

[0047] from Figure 1 It can be seen that when testing the Zn||I2 full cells assembled with the aqueous electrolyte in Example 1 and Comparative Example 1, under the condition of 1A / g, the battery assembled with the electrolyte in Comparative Example 1 could only work for about 700 cycles before failing, while the battery assembled with the electrolyte containing the long-lasting composite additive in Comparative Example 1 could cycle for more than 2000 cycles without failure, proving that the long-lasting composite additive can work in a long-term and stable manner.

[0048] Figure 2 The images show the surface morphology of the zinc anode in the Zn||I2 coin cells assembled with aqueous electrolytes in Comparative Example 1 and Example 1, where a represents Comparative Example 1 and b represents Example 1.

[0049] from Figure 2As can be seen from Figure a, the zinc anode deposited using the ordinary electrolyte in Comparative Example 1 exhibits a loose, flocculent dendritic morphology; in stark contrast, after using the electrolyte containing the long-lasting composite additive in Example 1, the zinc deposition layer becomes denser and smoother, exhibiting a uniform structure composed of stacked zinc sheets. Figure 2 As can be seen from Figure b), the long-lasting composite additive provided by the present invention significantly optimizes the deposition quality.

[0050] In summary, the aqueous electrolyte with long-lasting composite additives provided by this invention improves the stability, reversibility, and cycle life of battery cycles by inhibiting dendrite growth, minimizing side reactions, and ensuring uniform zinc deposition. This provides a reliable technical path and industrialization prospect for developing high-performance, long-life, and highly safe aqueous zinc-based energy storage systems.

[0051] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A long-acting compound additive, characterized in that, Includes main additives and guest additives; The structure of the main additive is shown in Formula 1: Formula 1, The structure of the guest additive is as shown in Formula 2: Formula 2; The R1 includes at least one of hydrogen, C1-C3 alkyl, methylthio, cyano, sulfonic acid, halogen, halogen-substituted C1-C3 alkyl, halogen-substituted methylthio, and halogen-substituted sulfonic acid. The R2 includes at least one of sulfonic acid group, carboxyl group, hydroxyl group, amino group and glucosyl group.

2. The long-acting compound additive according to claim 1, characterized in that, The molar ratio of the main additive to the guest additive is 1:(0.5~5).

3. The long-acting compound additive according to claim 1, characterized in that, The main additive is N-trifluoromethylthiosaccharin.

4. The long-acting compound additive according to claim 1 or 2, characterized in that, The guest additive is lauryl glucoside.

5. An aqueous electrolyte, characterized in that, It includes water, electrolyte salts, and additives, wherein the additives are the long-acting compound additives according to any one of claims 1 to 4; in the long-acting compound additives, the guest additives encapsulate the host additives to form micelle structures.

6. The aqueous electrolyte according to claim 5, characterized in that, The total mass of the long-acting compound additive accounts for 0.001~5 wt.% of the total mass of electrolyte salt and water.

7. The aqueous electrolyte according to claim 5, characterized in that, The electrolyte salt is a zinc salt; the zinc salt includes at least one of zinc sulfate, zinc trifluoromethanesulfonate, zinc perchlorate, zinc chloride, zinc nitrate, zinc acetate, and zinc difluorosulfonamide.

8. The aqueous electrolyte according to claim 5 or 7, characterized in that, The molar concentration of electrolyte salts in the aqueous electrolyte is 0.1~3 mol / L.

9. A zinc-based battery, comprising an electrolyte, a positive electrode, a negative electrode, and a separator, characterized in that, The electrolyte contains the long-acting composite additive as described in any one of claims 1 to 4, or the electrolyte is the aqueous electrolyte as described in any one of claims 5 to 8.

10. The zinc-based battery according to claim 9, characterized in that, The zinc-based battery is a zinc-ion battery, a zinc-air battery, or a zinc-based flow battery.

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