Composite additive for zinc ion battery electrolyte, zinc ion battery electrolyte as well as preparation method and application of zinc ion battery electrolyte

Abstract

The invention discloses a composite additive for a zinc ion battery electrolyte, the zinc ion battery electrolyte as well as a preparation method and application of the zinc ion battery electrolyte. The composite additive comprises a carbon nano tube and an anionic surfactant, and the carbon nano tube and the anionic surfactant can generate micelle action to form nano micelle particles. The zinc ion battery electrolyte comprises zinc ions and the composite additive for the zinc ion battery electrolyte. The composite additive disclosed by the invention has multiple functions, and can finally realize multifunctionality of inducing uniform nucleation of zinc at an interface and retarding dendritic crystals and various side reactions through multiple mechanisms such as regulation and control of an H bond network of water molecules, improvement of a hydrated zinc ion solvation structure, generation of a shielding layer after adsorption on the surface of a negative electrode, regulation and control of an electric field and the like. The zinc ion battery electrolyte realizes dendrite-free stable circulation of a zinc negative electrode in a symmetrical battery assembled by using the zinc ion battery electrolyte under various current densities and surface capacities, and the cycle life of the negative electrode is greatly prolonged.

Description

Technical Field

[0001] This invention relates to a composite additive, and more particularly to a composite additive for zinc-ion battery electrolytes, as well as a multifunctional aqueous zinc-ion battery electrolyte containing the composite additive, its preparation method and application, belonging to the field of electrolyte modification technology. Background Technology

[0002] Rechargeable aqueous zinc-ion batteries (azibs) have a high theoretical capacity (820 mAh g) due to their metallic zinc anode. -1 and 5854mAh cm -3 Zinc, with its advantages such as a lower redox potential (-0.763V vs. SHE), high safety, environmental friendliness, and abundant reserves (approximately 300 times that of lithium), is considered one of the most promising rechargeable batteries. However, as a negative electrode, zinc is more prone to dendrite formation, corrosion, and hydrogen evolution during cyclic charging and discharging than lithium. This leads to the failure of electrochemically active zinc, reduced battery cycle life, and short circuits, limiting its practical application.

[0003] To effectively suppress the side reactions that easily occur during the use of zinc anodes, this paper analyzes the underlying principles and proposes solutions. The first issue is the uneven nucleation on the anode surface during deposition. Zinc deposition on the anode includes nucleation and Zn deposition. 2+ The process involves ion diffusion and deposition growth. However, zinc ions tend to deposit at the dendrite protrusions on the smallest surface area. This "tip effect" further exacerbates the uneven distribution of the electric field on the anode surface, accelerates the three-dimensional growth of zinc longitudinally, and eventually penetrates the separator, causing short circuits and failure of active components. Therefore, it is necessary to control the flux of zinc ions at the electrode-electrolyte interface and the differential electric field.

[0004] Furthermore, in weakly acidic aqueous electrolytes, hydrogen evolution competition is an unavoidable parasitic reaction during zinc deposition / dissolution. Gas accumulation increases the internal pressure of the sealed battery, leading to internal expansion or electrolyte leakage. Hydrogen release not only reduces the coulombic efficiency (CE) of the zinc anode but also increases the OH- concentration, promoting the formation of the passivation product, basic zinc sulfate insulating layer, resulting in electrode deactivation. Therefore, it is necessary to block the contact between the negative electrode interface and active water molecules to reduce water side reactions, or to increase the hydrogen evolution potential by limiting the hydrogen bonding network of active water in the solvent.

[0005] Based on the solutions proposed above, most current studies have focused on modifying the electrolyte environment to suppress irreversible side reactions at the zinc metal anode. Compared to complex processes such as in-situ construction of the anode protective layer and membrane functionalization, directly introducing electrolyte additives into the zinc salt solution is simple and convenient, has a better effect on regulating zinc deposition behavior, and is more suitable for practical applications. Reported electrolyte additives, such as inorganic additives (lithium chloride, sodium sulfate, nickel sulfate), can form a positively charged SEI layer on the zinc anode surface, inducing uniform zinc ion deposition, but they cannot adapt to deposition at high current densities and have poor suppression effects on side reactions such as corrosion and hydrogen evolution. Organic additives, such as dimethyl sulfoxide (DMSO), acetone, ethylene glycol, nicotinamide, etc., can alleviate dendrite growth and suppress side reactions through various means such as shielding the electrostatic field, increasing Zn nucleation sites, adjusting Zn nucleation orientation, and regulating solvation structure. However, they all have varying degrees of toxicity and flammability, and are costly, making them unsuitable for practical applications. In addition, the introduction of most organic additives reduces the high conductivity of aqueous solutions to some extent, resulting in a decrease in ion migration rate and slow deposition kinetics.

[0006] In summary, existing methods for modifying electrolyte additives have the following drawbacks:

[0007] 1) The additive molecules themselves have poor conductivity, especially at high concentrations, which greatly reduces the high conductivity of the aqueous electrolyte and seriously affects the kinetic rate of zinc deposition reaction (zinc ion migration rate, interfacial reduction reaction rate).

[0008] 2) Its functionality is relatively singular, and it can only suppress a single side reaction through a certain action (accelerating the desolvation of hydrated ions, forming SEI at the reaction interface, etc.), making it difficult to take into account every side reaction.

[0009] 3) Many additive molecules are expensive and highly toxic (such as fluoride salts and most organic compounds) and highly flammable (such as pyridine, ethers, alcohols, etc.), which deviates from the original intention of water-based batteries to be green, environmentally friendly, low-cost, and highly safe.

[0010] 4) Most additives can only improve the dendrite problem of zinc anodes at lower currents, but not at higher current densities (>1 mA cm⁻¹). -2 Significant polarization or short-circuit failure occurs, and the deposition-dissolution coulombic efficiency is affected at high current densities (>5 mA cm⁻¹). -2 The battery exhibits rapid degradation under testing, with severe loss of active zinc that cannot be replenished in time, resulting in a significant reduction in battery cycle life. Summary of the Invention

[0011] The main objective of this invention is to provide a composite additive for zinc-ion battery electrolytes and its preparation method, so as to overcome the shortcomings of the prior art.

[0012] Another objective of this invention is to provide a multifunctional aqueous zinc-ion battery electrolyte containing the composite additive, its preparation method, and its application.

[0013] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0014] This invention provides a composite additive for zinc-ion battery electrolytes, comprising carbon nanotubes and anionic surfactants, wherein the carbon nanotubes and anionic surfactants can interact to form nanomicelle particles.

[0015] In some embodiments, the anionic surfactant is an amphiphilic anionic surfactant, whose hydrophobic chains self-assemble into nanomicelles through van der Waals forces, with the hydrophobic tails adsorbed on the surface of carbon nanotube bundles and the hydrophilic heads capable of binding with water or cations to form nanomicelle particles.

[0016] The present invention also provides a method for preparing the composite additive for zinc-ion battery electrolyte, which includes: mixing carbon nanotubes, anionic surfactants and water, ultrasonically mixing them evenly, and then centrifuging to obtain the composite additive for zinc-ion battery electrolyte.

[0017] This invention also provides the application of the composite additive for zinc-ion battery electrolyte in the preparation of zinc-ion battery electrolyte or zinc-ion energy storage device.

[0018] Accordingly, embodiments of the present invention also provide a zinc-ion battery electrolyte, which includes zinc ions and additives, wherein the additives are the aforementioned composite additives for zinc-ion battery electrolytes.

[0019] The present invention also provides a method for preparing the zinc-ion battery electrolyte, which includes: mixing zinc-ion battery electrolyte with zinc ions using composite additives to obtain the zinc-ion battery electrolyte.

[0020] Accordingly, this invention also provides a zinc-ion energy storage device, including a positive electrode, a negative electrode, and an electrolyte, wherein the electrolyte is the aforementioned zinc-ion battery electrolyte.

[0021] Compared with the prior art, the beneficial effects of the present invention include:

[0022] 1) The zinc-ion battery electrolyte provided by this invention achieves dendrite-free stable cycling of the zinc anode in symmetrical cells assembled using this zinc-ion battery electrolyte at various current densities and areal capacities. Compared with the environment of a single zinc sulfate aqueous solution, the cycle life of the anode is significantly improved.

[0023] 2) In the multifunctional electrolyte system provided by the present invention, uniform zinc ion diffusion achieves high deposition-dissolution coulombic efficiency with stable and long lifetime under high current density and areal capacity, and the high reversibility of deposition-dissolution behavior achieves high utilization rate of active zinc.

[0024] 3) The zinc-ion battery electrolyte composite additive provided by this invention has multiple functions. It can improve the solvation structure of hydrated zinc ions by regulating the H bond network of water molecules, generate a shielding layer after adsorption on the negative electrode surface, regulate the electric field, and so on. Ultimately, it can induce uniform nucleation of zinc at the interface, reduce dendrites and various side reactions. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram illustrating the preparation process of a zinc-ion battery electrolyte in a typical embodiment of the present invention;

[0027] Figure 2a Optical images of the ZnSO4-CNT-LAS electrolyte in Example 1 of the present invention and the ZnSO4 electrolyte in Comparative Example 1;

[0028] Figure 2b Raman spectra of the ZnSO4-CNT-LAS electrolyte in Example 1 of the present invention and the ZnSO4 electrolyte in Comparative Example 1;

[0029] Figure 3a and Figure 3b The figures show the cycle performance results of Zn / / Zn symmetric cells under different current densities and areal capacities for the ZnSO4-CNT-LAS electrolyte in Example 1 and the ZnSO4 electrolyte in Comparative Example 1, respectively.

[0030] Figure 4 The graph shows the coulombic efficiency of zinc deposition and dissolution at high current density for the ZnSO4-CNT-LAS electrolyte in Example 1 and the ZnSO4 electrolyte in Comparative Example 1.

[0031] Figure 5a The voltage window curves of the Zn / / Cu battery composed of the ZnSO4-CNT-LAS electrolyte in Example 1 of the present invention and the ZnSO4 electrolyte in Comparative Example 1 are shown.

[0032] Figure 5bThese are optical micrographs of zinc deposition in two different electrolytes: the ZnSO4-CNT-LAS electrolyte in Example 1 of the present invention and the ZnSO4 electrolyte in Comparative Example 1.

[0033] Figure 6a , Figure 6b The images show the ESI impedance spectra of two different electrolytes, namely the ZnSO4-CNT-LAS electrolyte in Example 1 of this invention and the ZnSO4 electrolyte in Comparative Example 1, and the comparison of their conductivity after conversion.

[0034] Figure 7a , Figure 7b The images show the XRD diffraction patterns and SEM images after corrosion in two different electrolytes: the ZnSO4-CNT-LAS electrolyte in Example 1 and the ZnSO4 electrolyte in Comparative Example 1.

[0035] Figure 8a The hydrogen evolution curves at negative potential during voltage window testing of Zn / / Ti batteries composed of ZnSO4-CNT-LAS electrolyte in Example 1 and ZnSO4 electrolyte in Comparative Example 1 are shown.

[0036] Figure 8b The oxygen evolution curves at positive potential during voltage window testing of Zn / / Ti batteries composed of ZnSO4-CNT-LAS electrolyte in Example 1 and ZnSO4 electrolyte in Comparative Example 1 are shown.

[0037] Figure 9 This is a schematic diagram showing the sedimentation of CNTs in zinc sulfate solution when only CNTs are used as an additive in Comparative Example 2.

[0038] Figure 10 The graph shows the cycle performance of the Zn / / Zn symmetric cell in Comparative Example 2 when only the same concentration of CNT was used as an additive.

[0039] Figure 11 The graph shows the cycle performance of the Zn / / Zn symmetric cell in Comparative Example 3 when only LAS at the same concentration was used as an additive. Detailed Implementation

[0040] In view of the problems existing in the prior art, after long-term research and extensive experiments, the inventors of this case proposed this technical solution, which mainly focuses on improving the side reactions of the zinc anode by introducing mixed additives into the electrolyte to regulate the zinc ion solvation structure, the solution H-bond network, and the zinc ion interfacial reduction behavior. Utilizing the multifunctionality of this composite additive, it simultaneously regulates the solution environment and the ion-electron field at the zinc anode interface, thereby suppressing dendrite formation and interfacial side reactions.

[0041] The following terms need to be explained in this invention:

[0042] 1. Carbon nanotubes (CNTs)

[0043] 2. Anionic surfactant: LAS;

[0044] 3. Saturated calomel electrode: SCE, standard hydrogen electrode: SHE.

[0045] The following will provide a further explanation of the technical solution, its implementation process, and its principles.

[0046] As one aspect of the technical solution of this invention, a composite additive for zinc-ion battery electrolyte (which may be simply referred to as "CNT-LAS composite additive") comprises carbon nanotubes (CNTs) and anionic surfactants (LAS), wherein the carbon nanotubes and the anionic surfactants can undergo micellar interactions to form nanomicelle particles. The introduction of highly conductive CNTs into this composite additive increases the electrolyte conductivity and accelerates zinc deposition kinetics.

[0047] In some preferred embodiments, the anionic surfactant is an amphiphilic anionic surfactant, whose hydrophobic chains self-assemble into nanomicelles through van der Waals forces, the hydrophobic tails adsorb onto the surface of carbon nanotube bundles, and the hydrophilic heads can bind with water or cations to form nanomicelle particles.

[0048] In some preferred embodiments, the carbon nanotubes and anionic surfactants are capable of generating electrostatic and hydrogen bonding interactions with water molecules.

[0049] In this invention, CNTs interact with amphiphilic LAS anionic surfactants. By adding a certain mass of CNTs to an aqueous solution of an anionic surfactant above the critical micelle concentration and then ultrasonically dispersing, micellar interaction occurs. The alkyl and other hydrophobic groups of the anionic surfactant self-assemble into hemispherical or cylindrical rod-shaped nanomicelles through van der Waals forces (hydrophobic / hydrophilic interactions) or π-π interactions. The hydrophobic tails of the anionic surfactant adsorb onto the surface of the carbon nanotube bundles, while the hydrophilic heads can bind to water and cations in the solution, thus remaining stable in aqueous or zinc salt solutions. The resulting CNT nanomicelle particles can remain stable in high-concentration zinc salt solutions for extended periods without aggregation, making them a relatively stable additive for use in zinc-ion energy storage devices.

[0050] Furthermore, as an amphiphilic substance, the anionic surfactant LAS binds to CNTs at its hydrophobic end, while a large number of negatively charged head groups are uniformly distributed on the surface of the nanotubes, bringing a large number of active sites. This enables the CNTs with high surface hydrophobicity to achieve the effect of binding zinc ions and adsorbing other ions to migrate together, ultimately achieving a dual stabilizing effect of ionic and electronic fields at the interface, inducing the uniform reduction of zinc at the negative electrode interface, and inhibiting dendrite growth.

[0051] In some preferred embodiments, the diameter of the carbon nanotubes is 0.8 to 10 nm.

[0052] In some preferred embodiments, the anionic surfactant LAS may include any one or a combination of two or more of sodium dodecylbenzenesulfonate (DDBS), sodium dodecyl sulfate (SDS), sodium cholate (SC), sodium tetradecyl sulfonate (XLT4), etc., but is not limited thereto.

[0053] In some preferred embodiments, the mass ratio of the anionic surfactant to carbon nanotubes is 1.5–100:1. If the concentration is below this range, CNTs cannot exist stably in the zinc salt aqueous solution, especially in high-concentration salt solutions where they quickly aggregate and fail to function as an additive. When the concentration ratio is above this range, excessive LAS will cause a decrease in the ionic conductivity of the zinc salt solution, a decrease in ion migration rate and mass transfer kinetics, and an excessively high total overpotential of the zinc symmetric cell, ultimately leading to rapid and uneven dendrite growth at the zinc anode.

[0054] The CNT-LAS composite additive provided by this invention can induce uniform nucleation of zinc ions at the electrode interface, alleviate dendrite growth, and improve the cycle life of the zinc anode under high current density. Furthermore, the strong H-bonding interaction between this CNT-LAS composite additive and water mitigates side reactions caused by polar water molecules at the anode interface, improves the corrosion resistance of the zinc anode, and to some extent suppresses hydrogen and oxygen evolution problems at the anode, thereby increasing the operating voltage window of the electrolyte.

[0055] In summary, the composite additive provided by this invention has multiple functions. It can improve the solvation structure of hydrated zinc ions by regulating the H-bond network of water molecules, generate a shielding layer after adsorption on the negative electrode surface, regulate the electric field, and so on. Ultimately, it can induce uniform nucleation of zinc at the interface, reduce dendrite formation, and mitigate various side reactions.

[0056] As one aspect of the technical solution of the present invention, it relates to a method for preparing a composite additive for zinc-ion battery electrolyte, which includes: mixing carbon nanotubes, anionic surfactants and water, and ultrasonically mixing them evenly, followed by centrifugation to obtain a composite additive for zinc-ion battery electrolyte.

[0057] In some preferred embodiments, the ultrasonic power of the ultrasonic mixture is 10% to 40%, and the ultrasonic time is 20 min to 100 min.

[0058] In some preferred embodiments, the centrifugation speed is greater than 10,000 r / min.

[0059] In summary, the preparation and introduction processes of the composite additive of the present invention are simple to operate, suitable for mass production, and have strong practical applicability; the reagents used in the preparation process are all non-toxic or low-toxic, and the cost is low.

[0060] As one aspect of the technical solution of the present invention, it relates to the application of the aforementioned composite additive for zinc-ion battery electrolyte in the preparation of zinc-ion battery electrolyte or zinc-ion energy storage device.

[0061] Furthermore, as one aspect of the technical solution of the present invention, a multifunctional aqueous zinc-ion battery electrolyte containing the composite additive includes zinc ions and an additive, wherein the additive is the aforementioned composite additive for zinc-ion battery electrolytes.

[0062] In some preferred embodiments, the zinc-ion battery electrolyte comprises: an aqueous solution of zinc sulfate and an additive, wherein the additive accounts for 0.001% to 10% of the volume of the aqueous solution of zinc sulfate.

[0063] In some preferred embodiments, the concentration of the zinc sulfate aqueous solution is 0.1–3 mol / L.

[0064] As one aspect of the technical solution of the present invention, a method for preparing a zinc-ion battery electrolyte includes: mixing zinc-ion battery electrolyte with zinc ions using composite additives to obtain the zinc-ion battery electrolyte.

[0065] In some preferred embodiments, the preparation method includes: adding zinc-ion battery electrolyte to zinc sulfate solution with composite additives, and ultrasonically oscillating to obtain the zinc-ion battery electrolyte.

[0066] Furthermore, the duration of the ultrasonic oscillation is 10–60 seconds.

[0067] As one of the more specific implementation schemes, please refer to Figure 1 As shown, the preparation method of the zinc-ion battery electrolyte may specifically include the following technical steps:

[0068] 1) Preparation of zinc sulfate aqueous solution: Weigh a certain amount of zinc sulfate heptahydrate, dissolve it in deionized water and stir. The concentration of the obtained zinc sulfate aqueous solution is 0.1-3 mol / L.

[0069] 2) Preparation of CNT-LAS composite additive: A certain mass of carbon nanotubes and anionic surfactants LAS (such as sodium dodecylbenzenesulfonate (DDBS), sodium dodecyl sulfate (SDS), sodium cholate (SC), sodium tetradecyl sulfonate (XLT4), etc.) are added to deionized water in a certain proportion. The mixture is ultrasonically mixed and dispersed evenly in a cell disruptor. Then, it is centrifuged at high speed (>10000 r / min), and the well-dispersed suspension is collected to obtain the CNT-LAS composite additive (such as...). Figure 1 (as shown);

[0070] 3) The CNT-LAS composite additive prepared in step 2) is added to the zinc sulfate aqueous solution in step 1) in different proportions. After ultrasonic oscillation for several seconds, zinc-ion battery electrolytes (i.e., ZnSO4-CNT-LAS electrolytes) with different addition concentrations are obtained, such as... Figure 1 As shown.

[0071] As another aspect of the technical solution of the present invention, it also relates to a zinc ion energy storage device, including a positive electrode, a negative electrode and an electrolyte, wherein the electrolyte is the aforementioned zinc ion battery electrolyte.

[0072] Furthermore, the zinc-ion energy storage device may be a zinc-ion battery, but is not limited to this.

[0073] The entire process will be described in detail below with reference to several embodiments and accompanying drawings. However, the scope of the claims of this invention is not limited to these embodiments. Furthermore, the embodiments only provide some conditions for achieving this objective, but do not imply that these conditions must be met to achieve this objective. All modifications conceived of or derived from the content disclosed in this invention are considered to be within the scope of protection of this invention.

[0074] Example 1

[0075] 1) Preparation of zinc sulfate aqueous solution: Weigh zinc sulfate heptahydrate, dissolve it in deionized water and stir. The concentration of the zinc sulfate aqueous solution obtained is 1 mol / L.

[0076] 2) Preparation of CNT-LAS composite additive: Carbon nanotubes and sodium dodecylbenzenesulfonate were added to deionized water and ultrasonically mixed and dispersed evenly in a cell disruptor. The ultrasonic power was 10% to 40% and the ultrasonic time was 20 min to 100 min. Then, the mixture was centrifuged at a high speed (>10000 r / min) and the well-dispersed suspension was collected to obtain the CNT-LAS composite additive. The mass ratio of sodium dodecylbenzenesulfonate to carbon nanotubes was 1.5 to 100:1.

[0077] 3) The CNT-LAS composite additive prepared in step 2) is added to the zinc sulfate aqueous solution in step 1) in different proportions (the volume percentage of the additive in the zinc sulfate aqueous solution is 0.001% to 10%). After ultrasonic oscillation for 10 to 60 seconds, zinc ion battery electrolytes (i.e., ZnSO4-CNT-LAS electrolytes) with different addition concentrations are obtained.

[0078] Comparative Example 1

[0079] Preparation of zinc sulfate aqueous solution: Weigh zinc sulfate heptahydrate, dissolve it in deionized water and stir. The concentration of the resulting zinc sulfate aqueous solution is 1 mol / L.

[0080] Optical images of the ZnSO4-CNT-LAS electrolyte in Example 1 and the ZnSO4 electrolyte in Comparative Example 1 are shown below. Figure 2a As shown, the Raman spectrum is as follows Figure 2b As shown.

[0081] Figure 3a and Figure 3b The figures show the cycle performance results of Zn / / Zn symmetric cells using the ZnSO4-CNT-LAS electrolyte in Example 1 and the ZnSO4 electrolyte in Comparative Example 1 at different current densities and areal capacities. The results show that the present invention achieves dendrite-free and stable cycling in symmetric cells assembled with the zinc anode using the ZnSO4-CNT-LAS electrolyte at various current densities and areal capacities. Compared with the environment of a single zinc sulfate aqueous solution, the cycle life of the anode is significantly improved.

[0082] Figure 4 The graphs show the coulombic efficiency of zinc deposition and dissolution at high current densities for the ZnSO4-CNT-LAS electrolyte in Example 1 and the ZnSO4 electrolyte in Comparative Example 1. The results show that in this invention, the uniform diffusion of zinc ions in the multifunctional electrolyte system achieves stable and long-life high deposition and dissolution coulombic efficiency at high current densities and areal capacities. The high reversibility of the deposition and dissolution behavior also achieves high utilization of active zinc.

[0083] Figure 5a The voltage window curves are shown for Zn / / Cu batteries composed of the ZnSO4-CNT-LAS electrolyte in Example 1 and the ZnSO4 electrolyte in Comparative Example 1. Figure 5b Optical micrographs of zinc deposition in two different electrolytes: the ZnSO4-CNT-LAS electrolyte in Example 1 and the ZnSO4 electrolyte in Comparative Example 1. The results show that during cycling, zinc nucleation at the electrode-electrolyte interface is finer and more uniform (e.g., ...). Figure 5b As shown), this increases the voltage window of the Zn / / Cu cell (as shown). Figure 5a (As shown).

[0084] Figure 6a , Figure 6b The figures show the ESI impedance spectra of the ZnSO4-CNT-LAS electrolyte in Example 1 and the ZnSO4 electrolyte in Comparative Example 1, as well as a comparison of the conductivity after conversion. The electrolyte conductivity test results show that, in this invention, the high conductivity of the ZnSO4-CNT-LAS electrolyte is improved compared to the zinc sulfate electrolyte due to the high conductivity of CNTs themselves.

[0085] Figure 7a and Figure 7b Self-corrosion experiments were conducted in different electrolyte environments, such as... Figure 7a The image shows the XRD diffraction patterns after etching in two different electrolytes: the ZnSO4-CNT-LAS electrolyte in Example 1 and the ZnSO4 electrolyte in Comparative Example 1. Figure 7b The images show SEM images of the zinc electrode after corrosion in different electrolytes. The results indicate that, in this invention, due to the adsorption and deposition of CNTs and LAS on the negative electrode surface, a protective layer is formed, which to some extent isolates the side reactions of polar water molecules on the electrode surface, improving the corrosion resistance of the zinc electrode. In a 10-20 day self-corrosion simulation experiment, it exhibited higher corrosion resistance than zinc sulfate aqueous solution.

[0086] Figure 8a and Figure 8b The results are from the Zn / / Ti battery voltage window test (LSV curve test). Figure 8a The hydrogen evolution curves at negative potential during voltage window testing of Zn / / Ti batteries composed of ZnSO4-CNT-LAS electrolyte in Example 1 and ZnSO4 electrolyte in Comparative Example 1 are shown. Figure 8b The figures show the oxygen evolution curves at positive potentials during voltage window testing of the Zn / / Ti battery composed of the ZnSO4-CNT-LAS electrolyte in Example 1 and the ZnSO4 electrolyte in Comparative Example 1. The results indicate that during the electrolyte voltage window testing, the electrostatic interactions and H-bonding between CNTs and LAS with water molecules restrict the H-bond network structure of active water molecules in the zinc sulfate aqueous solution. This leads to a certain degree of increase in both the hydrogen evolution and oxygen evolution potentials of the ZnSO4-CNT-LAS electrolyte, thus broadening the overall operating voltage window of the electrolyte.

[0087] Comparative Example 2

[0088] The difference between this comparative example and Example 1 is that the additive is only the same concentration of CNTs.

[0089] like Figure 9As shown, when CNTs were used as an additive at the same concentration, they failed to disperse well in the zinc sulfate electrolyte, exhibiting significant flocculation and sedimentation after a period of time, indicating instability. Zinc symmetric cells assembled using the electrolyte before flocculation showed good dispersion at a low current density of 1 mA cm⁻¹. -2 Significant polarization failure occurred after only 50 hours of cycling. Figure 10 The graph shows the cycle performance of a Zn / / Zn symmetric cell when only CNTs of the same concentration are used as an additive. Therefore, CNTs cannot be used as a standalone additive.

[0090] Comparative Example 3

[0091] The difference between this comparative example and Example 1 is that the additive is only the same concentration of LAS.

[0092] When using only LAS at the same concentration as an additive, zinc symmetric cells at a low current density of 2 mA cm⁻¹ -2 Significant short circuits and polarization appeared after only 40 hours of cycling, and the polarization potential plateau was unstable. Figure 11 The graph shows the cycle performance of a Zn / / Zn symmetric cell when only LAS at the same concentration is used as an additive. Therefore, anionic surfactants such as LAS cannot be used alone as additives.

[0093] In addition, the inventors of this case also conducted experiments with other raw materials and conditions listed in this specification, referring to the above embodiments, such as replacing sodium dodecylbenzenesulfonate with sodium dodecyl sulfate, sodium cholate, sodium tetradecyl sulfonate, etc., and similarly obtained zinc-ion battery electrolyte composite additives and zinc-ion battery electrolytes.

[0094] It should be understood that the above are merely specific application examples of the present invention and do not constitute any limitation on the scope of protection of the present invention. All technical solutions formed by equivalent transformations or equivalent substitutions fall within the scope of protection of the present invention.

Claims

1. A composite additive for zinc-ion battery electrolyte, characterized in that, include: Carbon nanotubes and anionic surfactants, wherein micelles can form nanomicelle particles through micelle interactions.

2. The composite additive for zinc-ion battery electrolyte according to claim 1, characterized in that: The anionic surfactant is an amphiphilic anionic surfactant. Its hydrophobic chains self-assemble into nanomicelles through van der Waals forces or π-π interactions. The hydrophobic tails are adsorbed on the surface of carbon nanotube bundles, and the hydrophilic heads can bind with water or cations to form nanomicelle particles. And / or, the carbon nanotubes and anionic surfactants are capable of generating electrostatic and hydrogen bonding interactions with water molecules; And / or, the diameter of the carbon nanotubes is 0.8 to 10 nm.

3. The composite additive for zinc-ion battery electrolyte according to claim 1, characterized in that: The anionic surfactant includes any one or a combination of two or more of sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, sodium cholate, and sodium tetradecyl sulfonate. And / or, the mass ratio of the anionic surfactant to the carbon nanotubes is 1.5 to 100:

1.

4. The method for preparing the composite additive for zinc-ion battery electrolyte according to any one of claims 1-3, characterized in that, include: Carbon nanotubes, anionic surfactants, and water were mixed and ultrasonically mixed to achieve uniform mixing. The mixture was then centrifuged to obtain a composite additive for zinc-ion battery electrolytes.

5. The preparation method according to claim 4, characterized in that: The ultrasonic power of the ultrasonic mixture is 10% to 40%, and the ultrasonic time is 20 min to 100 min; and / or, the centrifugation speed is greater than 10000 r / min.

6. The application of the composite additive for zinc-ion battery electrolyte according to any one of claims 1-3 in the preparation of zinc-ion battery electrolyte or zinc-ion energy storage device.

7. A zinc-ion battery electrolyte, characterized in that, include: Zinc ions and additives, wherein the additives are composite additives for zinc-ion battery electrolytes as described in any one of claims 1-3.

8. The zinc-ion battery electrolyte according to claim 7, characterized in that, include: The zinc sulfate aqueous solution and the additive, preferably, the additive accounts for 0.001% to 10% of the volume percentage of the zinc sulfate aqueous solution; preferably, the concentration of the zinc sulfate aqueous solution is 0.1 to 3 mol / L.

9. The method for preparing the zinc-ion battery electrolyte according to claim 7 or 8, characterized in that, include: The zinc-ion battery electrolyte is prepared by mixing zinc ions with a composite additive. Preferably, the preparation method includes: adding zinc-ion battery electrolyte to zinc sulfate solution with composite additives, and ultrasonically oscillating to obtain the zinc-ion battery electrolyte; Particularly preferred is that the ultrasonic oscillation time is 10 to 60 seconds.

10. A zinc ion energy storage device, comprising a positive electrode, a negative electrode, and an electrolyte, characterized in that: The electrolyte is the zinc-ion battery electrolyte as described in claim 7 or 8, and preferably, the zinc-ion energy storage device includes a zinc-ion battery.

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