A dynamically protected zinc-based aqueous electrolyte and applications thereof

Abstract

The application discloses a kind of zinc-based aqueous electrolyte of dynamic protection and application.The electrolyte of the application contains chitin nanocrystals, which can be used in aqueous zinc-ion batteries and capacitors.The zinc-based aqueous electrolyte of the application is non-toxic, environmentally friendly, safe and low-cost.When used in batteries and capacitors, it can change the solvation structure, induce uniform zinc deposition and build multiple functional interface protection layers, effectively protecting the zinc anode.On the other hand, it can act on multiple sites on the electrolyte and electrode surface, providing comprehensive protection for the zinc anode.Finally, and most importantly, during the charging and discharging cycle, chitin nanocrystals can perform dynamic protection, repeatedly affecting both electrodes and electrolyte, and effectively repairing damaged areas of the zinc anode to build a strong zinc anode, achieving dynamic protection throughout the entire process of the additive with high effectiveness.

Description

Technical Field

[0001] This invention relates to a zinc-based aqueous electrolyte and its application, particularly a dynamically protected zinc-based aqueous electrolyte and its application. Background Technology

[0002] Currently, the rapidly developing lithium-ion battery dominates large-scale smart grids and portable energy storage systems due to its high energy density. However, the high cost caused by the scarcity of lithium resources and the safety issues caused by organic electrolytes severely limit its further development. Compared to lithium metal, zinc metal has a lower potential (-0.762V vsSHE) and a higher theoretical capacitance (820mAh g / g). -1 Or 5854mAh L -1 With its significant advantages such as abundant zinc metal reserves, it has great potential in large-scale energy storage systems. Therefore, aqueous zinc-ion energy storage devices are also regarded as strong competitors for future secondary batteries.

[0003] However, during charge-discharge cycles, zinc ions (Zn) continuously precipitate at the electrode / electrolyte interface of aqueous zinc-ion energy storage devices. 2+ The deposition / dissolution reaction, along with the uneven charge distribution on the electrode surface and the ionization of active water molecules, leads to serious problems such as zinc dendrite growth, passivation, and side reactions during cycling. This results in severe issues such as low coulombic efficiency and short cycle life in aqueous zinc-ion energy storage devices, which seriously affects the inherently excellent electrochemical performance of the zinc anode and hinders the development of aqueous zinc-ion energy storage devices.

[0004] To improve the electrochemical performance of zinc anodes and achieve high-performance aqueous zinc-ion energy storage devices, researchers have proposed numerous strategies, including zinc metal anode structural design, artificial interface modification layers, membrane optimization, and electrolyte modification. Among these, electrolyte additive strategies have attracted widespread attention due to their simplicity, low cost, and ease of large-scale application. However, most current electrolyte additives suffer from limitations such as single function, limited application sites, and static protective behavior. This results in limited improvement in the performance of additives in aqueous zinc-ion energy storage devices during cycling, poor stability, and a high risk of sacrificing their protective function, making it difficult to achieve long-term stable charge-discharge and limiting their large-scale application. For example:

[0005] The literature, such as "Simultaneous tailoring of hydrogen evolution and dendrite growth via fertilizer-derived additive enables zinc anode interface stabilization," reports a method using fertilizer-derived N-methylthiourea additives to modulate the zinc-electrolyte interface, preferentially adsorbing onto the Zn surface, delaying water adsorption, and controlling Zn... 2+ The secondary diffusion of N-methylthiourea stabilizes the zinc / electrolyte interface, guides uniform zinc plating / stripping, and inhibits dendrite formation. However, N-methylthiourea itself is toxic and only acts at the zinc metal interface, which limits its effectiveness during cycling and prevents it from significantly improving the electrochemical performance of aqueous zinc-ion batteries.

[0006] In their article "Vitamin C Additives Synchronously Regulate the Center of Zinc Substrate d-Band / Weaken Zinc Ion Pauli Repulsion to Facilitate Reversible Zinc Anodes," Professors Xiong Shenglin and Xi Baojuan of Shandong University pointed out that the molecules and Zn 2+ The increased electrostatic charge and decreased Pauli repulsion decisively promote the hydration of vitamin C in Zn. 2+ The solvation structure replaces sulfate. Therefore, the alteration of the solvation coordination structure and microenvironment of the Zn substrate leads to a decrease in overpotential and an improvement in cycling stability, which contributes to the uniform and smooth deposition of Zn. However, vitamin C exhibits strong reducing properties and is easily oxidized and decomposed. This makes vitamin C additives not only functionally limited during cycling but also easily decomposed and sacrificed, resulting in limited effectiveness in improving electrochemical performance. Its susceptibility to sacrifice and static protection is detrimental to achieving ultra-stable zinc anodes.

[0007] A paper published by Professor Dunmin Lin's team at Sichuan Normal University, titled "Revealing the Solvation Structure and Electrolyte Interface through Carbonyl Chemistry to Obtain a Durable and Dendrite-Free Zinc Anode," points out that acetylacetone can be used to simultaneously modulate the solvation structure and the anode / electrolyte interface to achieve a durable, dendrite-free zinc anode. The paper discusses anode / electrolyte interface reconstruction and acetylacetone-induced [Zn(H₂O)₆] 2+ The combination of desolvation and solvent removal effectively suppresses side reactions and promotes uniform Zn deposition during charging and discharging. However, the problem of excessively thick protective layers caused by the continuous decomposition of acetylacetone during zinc plating / stripping is detrimental to extending the service life of the zinc anode.

[0008] In his article "Achieving Highly Reversible Zinc-Ion Batteries with Zinc-Phlegac Electrolytes," Professor Wang Hao of Hubei University reported the development of a zinc-phobic electrolyte containing succinate (SN) additives. SN electrolytes exhibit low affinity for zinc but strong affinity for the solid-state interface (SEI). The inherently zinc-phobic electrolyte reduces the affinity of zinc metal for the electrolyte, preventing hydrogen evolution and corrosion caused by interfacial water. Therefore, the SN electrolyte not only reduces zinc metal corrosion but also alters the growth trend of zinc hydroxide sulfate (ZHS), causing ZHS to tend to stack horizontally, forming a dense SEI protective layer on the Zn anode surface, effectively slowing down Zn corrosion and dendrite growth. However, during charge-discharge transitions, succinate cannot oscillate between the two electrodes of the zinc battery with changes in the electric field. Furthermore, the continuous auxiliary effect of succinate on the zinc anode surface, resulting in an excessively thick SEI protective layer, affects interfacial transfer kinetics, hindering the continuous and stable protection of the zinc anode.

[0009] Therefore, designing an additive that combines the advantages of diverse functions, wide application range, and dynamic protection behavior to promote multifunctional, all-round, full-process, and highly effective dynamic protection behavior in aqueous zinc ion energy storage devices during reciprocating cycles is of great significance for constructing high-performance aqueous zinc ion energy storage devices. However, there are few reports on achieving high-performance zinc anodes based on the dynamic protection of additives. Some of the reports are as follows:

[0010] For example, Professor Li Zhi's team at the University of Alberta published an article titled "Self-repairing interphase reconstructed in each cycle for highly reversible aqueous zinc batteries," reporting a highly reversible zinc-water battery in which graphitic carbon nitride quantum dot additives act as rapid colloidal ion carriers, assisting in the construction of a dynamic and self-healing protective mesophase. This real-time assembled mesophase achieves ion isolation and can actively regenerate in each battery cycle, giving the system a single Zn content. 2+ Conductivity and stable structural integrity enable timely adaptation to zinc deposition, thereby maintaining sustainable long-term protective effects.

[0011] For example, the team led by Yang Jian at Shandong University pioneered the use of ultrathin zirconium phosphate (ZrP) nanosheets as electrolyte additives to stabilize zinc anodes over a wide temperature range. On one hand, the ZrP nanosheet additive significantly enhances the charge mobility and increases the charge concentration of the Helmholtz layer, thereby improving the stability of Zn. 2+On the one hand, ZrP nanosheets can dynamically adsorb and desorb at the electrolyte / electrode interface. The dynamic interface established by ZrP nanosheets not only reduces the loss of ZrP during cycling but also suppresses side reactions and promotes uniform deposition. Simultaneously, it can adapt to the dynamic changes in the electrode surface during cycling.

[0012] However, compared to inorganic materials, bio-based organic materials have more designable chemical and physical structures, which can give them more functions, and bio-based materials from green sources are more conducive to sustainable development.

[0013] Chitosan nanocrystals are highly crystalline one-dimensional rod-shaped nanoparticles extracted from natural chitosan. They not only possess the characteristics of nanoparticles but also exhibit excellent biodegradability, mechanical properties, low cost, and self-assembly properties. However, there are currently no reports on the application of chitosan nanocrystals in zinc-based aqueous electrolytes to address the aforementioned technical problems in zinc-based aqueous electrolytes. Summary of the Invention

[0014] To address the aforementioned technical problems, this invention provides a dynamically protected zinc-based aqueous electrolyte and its application. The zinc-based aqueous electrolyte of this invention is non-toxic, environmentally friendly, highly safe, and low-cost. When used in batteries and capacitors, it possesses multiple functions: altering the solvation structure, inducing uniform zinc deposition, and constructing an interfacial protective layer, effectively protecting the zinc anode. Furthermore, it acts in multiple locations within the electrolyte and on the electrode surface of aqueous zinc-ion batteries, providing comprehensive protection for the zinc anode. Finally, and more importantly, during charge-discharge cycles, the additive exhibits dynamic protective behavior, repeatedly acting on both electrodes and the electrolyte, effectively repairing damaged areas of the zinc anode and constructing a robust zinc anode. This achieves the additive's full-process and highly effective dynamic protection. These characteristics and functions help solve key scientific problems such as inhibiting zinc dendrite formation and mitigating side reactions, realizing the additive's multifunctional, comprehensive, full-process, and highly effective dynamic protection in zinc-based energy storage devices, thereby constructing high-performance aqueous zinc-ion energy storage devices.

[0015] The technical solution of the present invention:

[0016] A dynamically protected zinc-based aqueous electrolyte containing chitin nanocrystals.

[0017] Preferably, the aforementioned dynamically protected zinc-based aqueous electrolyte is composed of water, zinc salt, and chitin nanocrystals.

[0018] Preferably, in the aforementioned dynamically protected zinc-based aqueous electrolyte, the molar concentration of zinc salt is 0.1-10 mol / L, and the mass ratio of chitin nanocrystals to zinc salt is 0.1:100-15:100.

[0019] Preferably, in the aforementioned dynamically protected zinc-based aqueous electrolyte, the concentration of zinc salt is 2-8 mol / L, and the mass ratio of chitosan nanocrystals to zinc salt is 5:100-10:100.

[0020] Preferably, in the aforementioned dynamically protected zinc-based aqueous electrolyte, the concentration of zinc salt is 5 mol / L, and the mass ratio of chitosan nanocrystals to zinc salt is 8:100.

[0021] Preferably, in the aforementioned dynamically protected zinc-based aqueous electrolyte, the zinc salt is one or any combination of any of the following: zinc sulfate, zinc trifluoromethanesulfonate, zinc nitrate, zinc chloride, or zinc acetate.

[0022] Application of the aforementioned dynamically protected zinc-based aqueous electrolyte in aqueous zinc-ion batteries.

[0023] Application of the aforementioned dynamically protected zinc-based aqueous electrolyte in aqueous zinc-ion capacitors.

[0024] An aqueous zinc-ion battery comprising the aforementioned dynamic protection zinc-based aqueous electrolyte.

[0025] An aqueous zinc-ion capacitor comprising the aforementioned dynamic protection zinc-based aqueous electrolyte.

[0026] The beneficial effects of this invention are:

[0027] 1. In the electrolyte provided by this invention, the surface of chitin nanocrystals exposes a large number of free reactive hydroxyl groups and acetamino groups. The introduced acetamino groups contain both a hydrogen bond acceptor and a donor, effectively confining water molecules in a two-site anchoring configuration, enhancing hydrogen bond interactions, and breaking the original hydrogen bonds between water molecules; while the large-scale hydrogen bonds formed between a certain number of hydroxyl groups and H2O molecules disrupt hydrated Zn. 2+ The solvation shell reduces the number of active H2O molecules, regulates the electrode interface and solvation structure, and is beneficial for uniform interface charge and promoting Zn 2+ Uniform deposition.

[0028] 2. In the electrolyte provided by this invention, chitin nanocrystals possess excellent self-assembly characteristics, enabling them to level the interface on the surface, forming a uniform and smooth interface and adsorbing in situ to form a self-healing protective film. Simultaneously, during cycling, when the interface suffers from uneven dendrite growth or external force damage, the chitin nanocrystals block dendrite growth or rapidly fill the damaged interface, thereby forming a stable and robust zinc anode. This chitin nanocrystal-based protective film not only exhibits strong zinc ion affinity and homogenizes the electric field and ion concentration to promote uniform zinc deposition, but also possesses excellent insulation properties to suppress parasitic reactions, resulting in a dendrite-free zinc metal electrode and extending the cycle life of the zinc metal electrode. After assembling a zinc symmetric battery with the electrolyte of this invention, at a current density of 10 mA cm⁻¹... -2 The surface area capacity is 1mAh cm -2 Under certain conditions, it can stably cycle for over 1374 hours under a bent zinc anode. Furthermore, it can achieve stable cycling even when the zinc anode surface is severely damaged, and can repair the damaged area to rebuild a robust zinc anode.

[0029] 3. In the electrolyte provided by this invention, the protective chitin nanocrystals, during charge and discharge, exhibit negatively charged hydroxyl groups and positively charged acetylamino groups on their surface that cyclically move between the two electrodes with changing electric fields. They spontaneously adsorb / desorb from the zinc anode, avoiding additive consumption and achieving multifunctional, comprehensive, full-process, and highly effective dynamic protection, providing sustainable long-term protection. Therefore, in the electrolyte containing chitin nanocrystals, dendrite-free and inherently stable Zn plating / stripping can be achieved. This solves the problems of hydrogen evolution, corrosion, passivation, and dendrite formation associated with zinc metal electrodes in aqueous electrolytes, while also improving the battery's charge / discharge efficiency and cycle stability. When the electrolyte of this invention is used to assemble a half-cell, at a current density of 40 mA cm⁻¹... -2 The surface area capacity is 1mAh cm -2 Under certain conditions, it can stably cycle for 843 cycles and has a high coulombic efficiency of 97.71%. After assembling a zinc symmetric battery with the electrolyte of this invention, it achieves a current density of 1 mA cm⁻¹. -2 The surface area capacity is 1mAh cm -2 Under these conditions, it can cycle stably for more than 2040 hours; and at 5mA cm -2 The surface area capacity is 1mAh cm -2 Under these conditions, it can stably cycle for over 1600 hours. Additionally, it can operate at 5-50 mA cm⁻¹. -2 High current density and 5mAh cm -2 With its high areal capacity, it exhibits excellent rate performance and reversibility. Furthermore, it demonstrates an exceptionally long cycle life in various zinc salt electrolytes, effectively protecting the zinc anode.

[0030] 4. The electrolyte provided by this invention has significant advantages such as low cost, safety, environmental friendliness, simple preparation method, wide applicability, dynamic self-healing, and dynamic protection. It has great application prospects and research value in aqueous zinc-based energy storage systems and other potential new energy battery fields. The aqueous zinc-based energy storage system electrolyte provided by this invention can achieve multifunctional, all-round, full-process, and highly effective dynamic protection behavior, and improves the cycle stability and lifespan of aqueous zinc-ion batteries and capacitors, providing a solution for realizing high-performance aqueous zinc-ion energy storage devices.

[0031] In summary, the zinc-based aqueous electrolyte of this invention is non-toxic, environmentally friendly, highly safe, and low-cost. When used in batteries and capacitors, it possesses multiple functions: altering the solvation structure, inducing uniform zinc deposition, and constructing an interfacial protective layer, effectively protecting the zinc anode. Furthermore, it acts in multiple locations within the electrolyte and on the electrode surface of the aqueous zinc-ion battery, providing comprehensive protection for the zinc anode. Finally, and more importantly, during charge-discharge cycles, the additive exhibits dynamic protective behavior, repeatedly acting on both electrodes and the electrolyte, effectively repairing damaged areas of the zinc anode and constructing a robust zinc anode. This achieves a full-process and highly effective dynamic protective effect. These characteristics and functions help solve key scientific problems such as inhibiting zinc dendrite formation and mitigating side reactions, realizing the multifunctional, comprehensive, full-process, and highly effective dynamic protective behavior of the additive in zinc-based energy storage devices, thereby constructing high-performance aqueous zinc-ion energy storage devices. Attached Figure Description

[0032] Figure 1 Electron images were taken of the electrolytes containing and without chitosan nanocrystals obtained in the comparative examples and Example 1 of this invention, after being left to stand for 10 days. The Tyndall effect was used to verify the dispersibility. It can be clearly seen that the electrolyte of Example 1 exhibits the Tyndall effect under laser irradiation, proving that the chitosan nanocrystals are uniformly dispersed and have good dispersibility in the zinc salt solution.

[0033] Figure 2 The electrolytes obtained in the comparative examples and Example 1 of this invention, with and without chitosan nanocrystal additives, showed a Raman spectral density of 950-1020 cm⁻¹. -1 Band diagram. It can be seen that compared with the comparative example, the ratio of solvent-separated ion pairs (SSIP) increased in Experimental Example 1, while the ratio of contact ion pairs (CIP) decreased. This confirms that the chitin nanocrystal additive changed the solvation structure of the traditional zinc hexahydrate, reduced the participation of some active water, and thus reduced the ionization of active water and dendrite growth.

[0034] Figure 3The electrolytes obtained in the comparative examples and Example 1 of this invention, with and without chitosan nanocrystal additives, showed a Raman spectral density of 2800-3800 cm⁻¹. -1 Band diagram. Compared to the comparative example, in Example 1 after the addition of chitosan nanocrystals, the proportion of strong hydrogen bonds significantly increased and the proportion of medium hydrogen bonds decreased, confirming that the chitosan nanocrystal additive can enhance the Zn... 2+ The surrounding bound H2O molecules are released into the electrolyte and the number of active H2O molecules is reduced, thus further confirming that chitin nanocrystal additives can change the solvation structure.

[0035] Figure 4 The images show SEM images of zinc foil immersed in the electrolytes obtained in the comparative example and Example 1 for 5, 15, and 30 days. In the comparative example without chitosan nanocrystalline additive, the zinc foil surface was uneven, with numerous corrosion cracks and pits, and the corrosion worsened with increasing immersion time. However, when immersed in the electrolyte of Example 1 containing chitosan nanocrystalline additive, its surface was clearly observed to be extremely uniform and smooth, remaining so even after 30 days of immersion. This demonstrates that the chitosan nanocrystalline additive preferentially adsorbs onto the zinc foil surface and forms a protective layer, significantly reducing the corrosion of the zinc foil by the ZnSO4 solution.

[0036] Figure 5 The zinc symmetric cells assembled with the electrolytes obtained in the comparative examples and Example 1 of this invention, with and without chitosan nanocrystal additives, were used at a current density of 5 mA cm⁻¹. -2 The surface area capacity is 1mAh cm -2 SEM images at different cycle counts are shown. In the comparative example without chitosan nanocrystal additives in the electrolyte, a large number of dendrites gradually grow on the zinc anode surface as the number of cycle counts increases. In Example 1, which contains chitosan nanocrystal additives in the electrolyte, the zinc anode surface maintains uniform planar growth as the number of cycle counts increases, forming a stable and robust zinc anode interface.

[0037] Figure 6 The zinc symmetric cells assembled with the electrolytes obtained in the comparative examples and Example 1 of this invention, with and without chitosan nanocrystal additives, were used at a current density of 5 mA cm⁻¹. -2 The surface area capacity is 1mAh cm -2 AFM images were obtained after 60 cycles. In the comparative example without chitosan nanocrystal additive in the electrolyte, severe dendrite growth was observed on the zinc anode surface. In Example 1, which contained chitosan nanocrystal additive in the electrolyte, the zinc anode surface was smooth and flat. This confirms that chitosan nanocrystal additive can effectively induce uniform deposition of zinc along the (002) crystal plane.

[0038] Figure 7The zinc symmetric cells assembled with the electrolytes obtained in the comparative examples and Example 1 of this invention, with and without chitosan nanocrystal additives, were used at a current density of 50 mA cm⁻¹. -2 In-situ optical microscopy images after 60 minutes of cycling. In the comparative example without chitosan nanocrystal additives in the electrolyte, a large number of dendrites gradually grew on the zinc anode surface as the cycling time increased. In Example 1, which contained chitosan nanocrystal additives in the electrolyte, the zinc anode surface maintained uniform planar growth as the cycling time increased, forming a stable and robust zinc anode interface.

[0039] Figure 8 The zinc half-cells assembled with the electrolytes obtained in the comparative examples and Example 1 of this invention, with and without chitosan nanocrystal additives, were tested at a current density of 40 mA cm⁻¹. -2 The surface area capacity is 1mAh cm -2 Long-cycle testing was conducted. Compared to the comparative example, Example 1 with added chitosan nanocrystals was able to cycle stably for over 843 cycles while maintaining a coulombic efficiency of 97.71%, confirming that the addition of chitosan nanocrystals greatly inhibited dendrite growth and mitigated side reactions.

[0040] Figure 9 The zinc symmetric cells assembled with the electrolytes obtained in the comparative examples and Example 1 of this invention, with and without chitosan nanocrystal additives, were used at a current density of 1 mA cm⁻¹. -2 The surface area capacity is 1mAh cm -2 The following is a graph showing the long-cycle performance. Example 1, with the addition of chitosan nanocrystals, exhibits a stable cycle life exceeding 2000 hours, which is 5 times that of the comparative example. This demonstrates that the addition of chitosan nanocrystals significantly improves the stability of the zinc anode.

[0041] Figure 10 The zinc symmetric cells assembled using the electrolytes obtained in the comparative examples and Example 1 of this invention, with and without chitosan nanocrystal additives, operate at a high current density of 5 mA cm⁻¹. -2 The surface area capacity is 1mAh cm -2 The following is a long-cycle performance graph. It is clearly observed that the zinc symmetric battery with the 1M ZnSO4 solution electrolyte containing chitosan nanocrystals exhibits stable cycling for over 1600 hours, far exceeding that of the 1M ZnSO4 solution electrolyte without chitosan nanocrystals. This demonstrates that the addition of chitosan nanocrystals effectively alters the solvation structure, guiding the uniform deposition of zinc ions; simultaneously, it promotes zinc ion migration kinetics and facilitates rapid desolvation reactions.

[0042] Figure 11This diagram shows the rate performance of zinc symmetric batteries assembled with the electrolytes obtained in the comparative examples and Example 1 of this invention, with and without chitosan nanocrystal additives, at different current densities. It can be clearly observed that the symmetric batteries containing chitosan nanocrystal additives perform well at different current densities (5-50 mA cm⁻¹). -2 It exhibits good rate performance and reversibility, proving that chitin nanocrystal additives can effectively regulate zinc ion deposition and guide zinc solvation migration and desolvation transformation.

[0043] Figure 12 With the comparative example and Example 1 swapped for the present invention, the assembled zinc symmetric cell operates at a current density of 1 mA cm⁻¹. -2 The surface area capacity is 1mAh cm -2 The following is a graph showing the long-cycle performance. First, using a zinc symmetric battery assembled in the comparative example, after a short-circuit cycle, the electrolyte of Example 1 was replaced, and the inhibition behavior of chitosan nanocrystals on the dendrite-severe zinc anode surface was observed. It can be found that even on the dendrite-severe zinc anode surface, Example 1 with added chitosan nanocrystals can still cycle stably, thus achieving a long cycle life.

[0044] Figure 13 The soft-pack symmetrical battery assembled in Comparative Example and Example 1 of this invention, with a bending radius R = 1 cm, exhibits high current density of 10 mA / cm². -2 The surface area capacity is 1mAh cm -2 The following is a graph showing the long-cycle performance. The flat zinc anode exhibits a uniform electric field and ion concentration. To further verify that chitosan nanocrystals can achieve a healthy and robust interfacial reaction by uniformizing the electric field and reducing the ion concentration gradient, a bent pouch cell was used to exacerbate the uneven interfacial reaction. Based on the self-assembly characteristics of chitosan nanocrystals, they can homogenize the interfacial reaction, thereby constructing a healthy zinc anode. It can be observed that the zinc symmetric battery assembled in Example 1 can stably cycle for over 6878 cycles, accumulating over 1473 hours, which greatly increases the practicality and applicability of zinc-based energy storage devices.

[0045] Figure 14 As a comparative example and Example 1 of the present invention, the current density was 5 mA cm⁻¹. -2 The surface area capacity is 1mAh cm -2 In-situ Fourier transform infrared spectroscopy was performed under charging conditions. The concentration of v(-SO3) in the comparative electrolyte was measured. 2- The strengths of α and β (-OH) decreased continuously with increasing deposition time, indicating that sulfur-containing compounds and active water molecules in the electrolyte system were continuously reacted at the zinc anode, leading to hydrogen evolution reaction and the generation of a large number of byproducts. In contrast, the strengths in Example 1 remained stable, suggesting that a healthy and stable interfacial chemical reaction in the electrolyte is beneficial for achieving a zinc anode with a high cycle life.

[0046] Figure 15 Images showing the surface condition of the zinc anode in a zinc symmetric cell assembled using a severely damaged (marked with a letter B) zinc anode at different numbers of cycles, as well as at 10 mA cm⁻¹, for comparative examples and Example 1 of the present invention. -2 and 1mAh cm -2 Long-term cycling tests were conducted. The comparative example, under severely damaged conditions, exhibited a cycle life of less than 200 hours and extremely uneven surface deposition due to its non-uniform interfacial electric field and tip growth. In contrast, Example 1 achieved stable cycling for over 390 hours and was able to repair the damaged interface, resulting in a smooth and flat zinc anode.

[0047] Figure 16 The zinc symmetric cells assembled with the electrolytes obtained in the comparative examples and Example 2 of this invention, with and without chitosan nanocrystal additives, were used at a current density of 1 mA cm⁻¹. -2 The surface area capacity is 1mAh cm -2 The following is a graph showing the long-cycle performance. Example 2, with the addition of chitosan nanocrystals, exhibits a stable cycle life exceeding 980 hours, nearly 10 times that of the comparative example. This demonstrates that the addition of chitosan nanocrystals significantly improves the stability of the zinc anode and can stably enhance electrochemical performance in different zinc salt systems.

[0048] Figure 17 The zinc symmetric cells assembled with the electrolytes obtained in the comparative examples and Example 3 of this invention, with and without chitosan nanocrystal additives, were used at a current density of 1 mA cm⁻¹. -2 The surface area capacity is 1mAh cm -2 The following is a graph showing the long-cycle performance. Example 3, with the addition of chitosan nanocrystals, exhibits a stable cycle life exceeding 1120 hours, which is 7 times that of the comparative example. This demonstrates that the addition of chitosan nanocrystals effectively protects the zinc anode and can stably improve electrochemical performance in different zinc salt systems. Detailed Implementation

[0049] The present invention will be further described below with reference to embodiments, but these embodiments are not intended to limit the scope of the invention.

[0050] Embodiments of the present invention

[0051] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0052] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0053] The following is a method for preparing chitin nanocrystals: 10g of chitin was placed in a 500mL three-necked flask, 3M hydrochloric acid aqueous solution was added, and the flask was placed in an oil bath at 124℃ for reflux acid hydrolysis and boiling for 3h. After acid hydrolysis, the flask was centrifuged at 8000rpm for 10min and the supernatant (slightly yellow) was poured off. Then, 1000mL of deionized water was added for washing, and the flask was centrifuged again and the supernatant was poured off. Another 250mL of deionized water was added, and the flask was sonicated for 15min. The flask was then added to a dialysis bag with a molecular weight cutoff of 8000-4000 and dialyzed for three days, during which the deionized water was changed several times. The flask was then freeze-dried for later use.

[0054] In the following embodiments, the battery performance tests were all conducted using the Chenhua Battery Testing System. In the embodiments below, polished zinc foil was used as the positive and negative electrodes of the symmetrical battery, and polished zinc foil and copper foil were used as the positive and negative electrodes of the half-cell, respectively. Glass fiber membrane was used as the separator, and 1M ZnSO4 solution containing chitin nanocrystal additive was used as the electrolyte. CR2032 button batteries or pouch batteries were assembled in an air atmosphere and electrochemical stability tests were conducted under constant current density and constant time.

[0055] Comparative examples of the present invention

[0056] (1) 2.8756 g of zinc sulfate heptahydrate and an appropriate amount of deionized water were diluted to 10 mL in a volumetric flask and dissolved completely at room temperature to obtain a 1 M ZnSO4 solution.

[0057] (2) Using 1M ZnSO4 solution as electrolyte, zinc foil as positive and negative electrode, and glass fiber membrane as separator, a CR2032 button cell was assembled in an air atmosphere and its electrochemical stability was tested.

[0058] Embodiment 1 of the present invention

[0059] (1) 0.0288g of chitin nanocrystals, 2.8756g of zinc sulfate heptahydrate and an appropriate amount of deionized water were diluted to 10mL in a volumetric flask and dissolved completely at room temperature to obtain a 1.0wt% chitin nanocrystal 1M ZnSO4 solution.

[0060] (2) A CR2032 button cell was assembled in an air atmosphere using a ZnSO4 solution containing 1.0 wt% chitin nanocrystals as the electrolyte, zinc foil as the positive and negative electrodes, and a glass fiber membrane as the separator.

[0061] Embodiment 2 of the present invention

[0062] (1) 0.0364 g of chitin nanocrystals, 3.6353 g of zinc trifluoromethanesulfonate and an appropriate amount of deionized water were diluted to 10 mL in a volumetric flask and dissolved completely at room temperature to obtain a 1 M (CF3SO3)2Zn solution of 1.0 wt% chitin nanocrystals.

[0063] (2) A CR2032 button cell was assembled in an air atmosphere using a (CF3SO3)2Zn solution of 1.0wt% chitin nanocrystals as electrolyte, zinc foil as positive and negative electrodes, and glass fiber membrane as separator.

[0064] Embodiment 3 of the present invention

[0065] (1) 0.0136 g of chitin nanocrystals, 1.3632 g of zinc chloride and an appropriate amount of deionized water were diluted to 10 mL in a volumetric flask and dissolved completely at room temperature to obtain a 1.0 wt% chitin nanocrystal 1 M ZnSO4 solution.

[0066] (2) A CR2032 button cell was assembled in an air atmosphere using a ZnSO4 solution containing 1.0 wt% chitin nanocrystals as the electrolyte, zinc foil as the positive and negative electrodes, and a glass fiber membrane as the separator.

[0067] Embodiment 4 of the present invention

[0068] (1) 0.2908g of chitin nanocrystals, 14.5412g of zinc trifluoromethanesulfonate and an appropriate amount of deionized water were diluted to 10mL in a volumetric flask and dissolved completely at room temperature to obtain a 2.0wt% chitin nanocrystal 4M (CF3SO3)2Zn solution.

[0069] (1) A button cell of CR2032 was assembled in an air atmosphere using a (CF3SO3)2Zn solution of 2.0wt% chitin nanocrystals as electrolyte, zinc foil as positive and negative electrodes, and glass fiber membrane as separator.

[0070] Embodiment 5 of the present invention

[0071] (1) 0.6981g of chitin nanocrystals, 5.7512g of zinc sulfate heptahydrate, 2.9749g of zinc nitrate hexahydrate and an appropriate amount of deionized water were diluted to 10mL in a volumetric flask and dissolved completely at room temperature to obtain a 3M zinc salt mixed solution of 8.0wt% chitin nanocrystals.

[0072] (2) A CR2032 button cell was assembled in an air atmosphere using a zinc salt mixed solution of 8.0 wt% chitin nanocrystals as electrolyte, zinc foil as positive and negative electrodes, and glass fiber membrane as separator.

[0073] Embodiment 6 of the present invention

[0074] (1) 0.7417g of chitin nanocrystals, 2.8756g of zinc sulfate heptahydrate, 1.8177g of zinc trifluoromethanesulfonate, 1.4875g of zinc nitrate hexahydrate and an appropriate amount of deionized water were diluted to 10mL in a volumetric flask and dissolved completely at room temperature to obtain a 2M zinc salt mixed solution of 12.0wt% chitin nanocrystals.

[0075] (2) A CR2032 button cell was assembled in an air atmosphere using a 12.0wt% zinc salt mixed solution of chitin nanocrystals as electrolyte, zinc foil as positive and negative electrodes, and glass fiber membrane as separator.

[0076] Embodiment 7 of the present invention

[0077] (1) 0.3813g of chitin nanocrystals, 0.9088g of zinc trifluoromethanesulfonate, 0.7437g of zinc nitrate hexahydrate, 0.3408g of zinc chloride, 0.5487g of zinc acetate and an appropriate amount of deionized water were diluted to 10mL in a volumetric flask and dissolved completely at room temperature to obtain a 1M zinc salt mixed solution of 15.0wt% chitin nanocrystals.

[0078] (2) A CR2032 button cell was assembled in an air atmosphere using a zinc salt mixed solution of 15.0 wt% chitin nanocrystals as electrolyte, zinc foil as positive and negative electrodes, and glass fiber membrane as separator.

[0079] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A dynamically protected zinc-based aqueous electrolyte, characterized in that: It contains chitin nanocrystals.

2. The dynamically protected zinc-based aqueous electrolyte according to claim 1, characterized in that: The electrolyte is composed of water, zinc salt and chitin nanocrystals.

3. The dynamically protected zinc-based aqueous electrolyte according to claim 2, characterized in that: In the electrolyte, the molar concentration of zinc salt is 0.1-10 mol / L, and the mass ratio of chitin nanocrystals to zinc salt is 0.1:100-15:

100.

4. The dynamically protected zinc-based aqueous electrolyte according to claim 3, characterized in that: In the electrolyte, the concentration of zinc salt is 2-8 mol / L, and the mass ratio of chitin nanocrystals to zinc salt is 5:100-10:

100.

5. The dynamically protected zinc-based aqueous electrolyte according to claim 4, characterized in that: The electrolyte contains 5 mol / L zinc salt and the mass ratio of chitin nanocrystals to zinc salt is 8:

100.

6. The dynamically protected zinc-based aqueous electrolyte according to claim 2, characterized in that: The zinc salt is one or any combination of any of the following: zinc sulfate, zinc trifluoromethanesulfonate, zinc nitrate, zinc chloride, or zinc acetate.

7. The application of a dynamically protected zinc-based aqueous electrolyte according to any one of claims 1-6 in an aqueous zinc-ion battery.

8. The application of a dynamically protected zinc-based aqueous electrolyte according to any one of claims 1-6 in an aqueous zinc-ion capacitor.

9. An aqueous zinc-ion battery comprising the zinc-based aqueous electrolyte with dynamic protection as described in any one of claims 1-6.

10. An aqueous zinc-ion capacitor comprising the zinc-based aqueous electrolyte with dynamic protection as described in any one of claims 1-6.

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