Aqueous zinc ion battery containing oxidation-reduction medium and preparation method of aqueous zinc ion battery

Abstract

The invention relates to the field of energy storage batteries. The invention provides a water-based zinc ion battery containing a redox medium and a preparation method of the water-based zinc ion battery. The battery comprises a shell, a positive plate, a diaphragm, a negative plate and electrolyte, the positive plate and the negative plate are oppositely arranged at two ends in the shell, the diaphragm is arranged between the positive plate and the negative plate, and the electrolyte is filled in the shell and is in contact with the positive plate and the negative plate. The electrolyte is an aqueous solution containing Zn (CF3SO3) 2, and 10-methylphenothiazine is dissolved in the electrolyte. The preparation method comprises the following steps: S1, dissolving Zn (CF3SO3) 2 powder in deionized water to obtain a basic electrolyte; s2, 10-methylphenothiazine powder is added into the basic electrolyte, and an oxidation reduction electrolyte is formed; and S3, sequentially arranging a positive plate, a diaphragm and a negative plate in the shell, injecting a redox electrolyte, and sealing and assembling to obtain the water-based zinc ion battery. According to the invention, dynamic regulation and control of the deposition behavior of the zinc negative electrode are realized, and the cycle life and stability of the battery are improved.

Description

Technical Field

[0001] The present application relates to the field of energy storage batteries, and more specifically, to an aqueous zinc ion battery containing a redox medium and a preparation method thereof. Background Art

[0002] Aqueous zinc-ion batteries (Zn-ion batteries) are becoming an important development direction for the next generation of energy storage devices due to their high safety, low cost, and environmental friendliness. These batteries typically use zinc metal as the negative electrode material, exhibiting high theoretical capacity and low reduction potential, making them suitable for applications such as large-scale energy storage, power tools, and portable electronics. However, the zinc negative electrode is susceptible to dendritic growth and accompanying side reactions such as hydrogen evolution and corrosion during long-term cycling. These phenomena lead to rapid capacity decay, a sharp increase in internal resistance, and even premature failure, severely restricting its practical application.

[0003] In response to the above problems, studies have attempted to improve them from multiple directions, such as constructing a three-dimensional conductive skeleton structure to increase the electrode specific surface area and enhance the zinc ion channel; introducing coatings or interface modification materials on the surface of the zinc negative electrode to stabilize the electrode interface; optimizing the diaphragm structure to regulate the ion flux distribution and alleviate local concentration polarization; or using non-traditional media such as ionic liquids and gel electrolytes to reduce the risk of side reactions. However, these solutions generally have problems such as complex preparation process, high material cost or poor long-term cycle adaptability, and it is difficult to meet the comprehensive requirements of scalability, safety and stability for practical applications. In contrast, the introduction of functional additives into aqueous electrolytes to assist in regulating the deposition behavior of zinc has shown unique technical advantages. The trace addition of molecules or ions with specific functions can precisely regulate the solvation structure, transport kinetics and deposition behavior of zinc ions at the negative electrode interface, effectively inhibiting the nucleation and growth of dendrites.

[0004] Therefore, there is an urgent need to construct an aqueous electrolyte system with good electrochemical stability and the ability to reduce the activity of side reactions during battery use, thereby improving the service life of aqueous zinc-ion batteries from the source. Summary of the Invention

[0005] The object of the present invention is to provide an aqueous zinc ion battery containing a redox medium and a preparation method thereof, in order to address the deficiencies in the above-mentioned prior art and solve the problem in the prior art of limited battery stability caused by dendrite growth of zinc negative electrode.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows: This application provides an aqueous zinc-ion battery containing a redox medium. The aqueous zinc-ion battery includes a housing, a positive electrode sheet, a separator, a negative electrode sheet, and an electrolyte. The positive and negative electrode sheets are disposed at opposite ends of the housing, the separator is disposed between the positive and negative electrode sheets, and the electrolyte fills the housing and contacts the positive and negative electrode sheets. The electrolyte is an aqueous solution containing zinc trifluoromethanesulfonate (Zn(CF3SO3)2), in which 10-methylphenothiazine (MPT) is dissolved.

[0007] This application introduces MPT as a redox medium into the electrolyte containing zinc trifluoromethanesulfonate to construct a control system with dual functions of charge regulation and interface stabilization, aiming to inhibit dendrite formation, activate failed zinc and maintain the balance of interfacial reactions, thereby extending the cycle life of the battery. Zinc trifluoromethanesulfonate, as an electrolyte salt, has good water solubility and conductivity, and its anion has a weak coordination ability, which helps to build a stable zinc ion migration channel and enhance the redox activity and interface regulation effect of MPT. The MPT molecule has reversible redox properties and can participate in electron transfer during charging and discharging, and realize dynamic synergistic regulation in zinc deposition and stripping reactions. During the discharge stage of zinc deposition, electrons flow from the external circuit to the negative electrode, and a local high electric field area is easily formed on the electrode surface, inducing Zn 2+ In this process, MPT accepts excess electrons to relieve the concentration of interface charge and balance the local reaction rate, thereby promoting the Zn 2+ It is uniformly deposited along the plane, effectively inhibiting the formation of dendrites. During the charging stage of zinc stripping, MPT assists in the uniform oxidation of metallic zinc by releasing electrons, reducing the stripping resistance and improving the integrity of the electrode interface. At the same time, insulating "dead zinc" areas are inevitably formed during long battery cycles, blocking electron transmission and causing capacity loss. The redox properties of MPT can achieve electron redistribution near the "dead zinc" area, assist in re-establishing local reaction paths, and gradually reduce the "dead zinc" that was originally unable to participate in the reaction to recyclable active zinc, thereby restoring the electrode reaction activity. Through the above mechanism, MPT realizes multi-dimensional coordinated regulation of the electrochemical behavior of the zinc negative electrode, improves the deposition uniformity, reaction integrity and material recycling efficiency of the zinc negative electrode, and effectively improves the cycle life and stability of the battery.

[0008] Furthermore, the concentration of Zn(CF3SO3)2 is 1-3 mol / L, and the concentration of 10-methylphenothiazine is 1-10 mmol / L. This ratio provides a moderate driving force for the migration of zinc ions in the electrolyte while ensuring a sufficient concentration of MPT on the electrode surface to complete the redox cycle, which helps to continuously and stably produce a buffered charge regulation effect.

[0009] Furthermore, the pH value of the electrolyte is 3-5. The weakly acidic environment inhibits the side reaction rate of zinc and water, effectively reducing the interface disturbance during hydrogen evolution, thereby maintaining the stability of the deposition reaction.

[0010] Furthermore, the positive electrode is a composite electrode constructed on a metal foil. This structure provides an excellent electron channel, improves the conductivity of the reaction zone and the electron lateral diffusion rate, and makes the positive electrode oxidation reaction more evenly distributed.

[0011] Furthermore, the positive electrode sheet includes a manganese dioxide material, the negative electrode sheet is a metallic zinc material, and the separator is a glass fiber material.

[0012] Furthermore, the electrolyte contains conductive nanoparticles, which can serve as auxiliary electron channels to assist MPT in activating the "dead zinc" area.

[0013] The present application also proposes a method for preparing an aqueous zinc ion battery containing a redox medium, the method comprising the following steps: S1. Dissolve Zn(CF3SO3)2 powder in deionized water and stir to obtain a basic electrolyte; S2. adding 10-methylphenothiazine powder to the base electrolyte and dissolving it under magnetic stirring to form a redox electrolyte; S3. Place the positive electrode sheet, diaphragm and negative electrode sheet in sequence inside the shell, inject redox electrolyte, and seal and assemble into an aqueous zinc ion battery.

[0014] Furthermore, in S1, the stirring temperature is 20-25°C and the stirring time is 10-15 minutes, until the solution is clear and transparent, ensuring that the Zn in the electrolyte is 2+ Dissolve fully to avoid precipitation or concentration differences affecting the uniformity of subsequent reactions.

[0015] Furthermore, in S2, 10-methylphenothiazine is added to the base electrolyte under an inert atmosphere and magnetically stirred until completely dissolved. This ensures its stability and inhibits side reactions or slow oxidation caused by oxygen.

[0016] Furthermore, in S3, the positive electrode sheet is made by mixing manganese dioxide, conductive carbon black, and polyvinylidene fluoride in a mass ratio of 8:1:1, dispersing it in N-methylpyrrolidone as a solvent, coating it on the surface of a metal foil, and drying it. This positive electrode sheet preparation method improves the utilization rate of active materials and the interface contact performance, helping to achieve uniform discharge and rapid electron transfer.

[0017] Compared with the prior art, the present invention has the following advantages: By introducing MPT as a redox medium into the electrolyte of aqueous zinc ion batteries, the present invention constructs a synergistic control system with charge buffering and interface regulation functions. MPT can accept electrons in the discharge stage to balance the interface reaction rate, induce Zn 2+ It is uniformly deposited on the surface of the negative electrode, effectively inhibiting the formation of dendrites; it releases electrons during the charging stage to assist in the uniform oxidation of metallic zinc and promote the stable stripping of zinc. For the "dead zinc" area generated during the cycle, the reversible redox characteristics of MPT can realize electron redistribution in its adjacent area, rebuild the local reaction pathway, and gradually reduce the inactive metal to active zinc that can participate in the reaction, effectively improving the utilization efficiency of the material. Starting from the microscopic reaction path, this mechanism realizes the dynamic regulation of the zinc negative electrode deposition behavior, effectively improving the cycle stability and service life of the battery. Compared with the traditional method of structural modification or diaphragm optimization, the present invention introduces trace functional molecules from the reaction mechanism level, does not rely on complex preparation processes or high-cost materials, and has better system compatibility and large-scale application potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of an aqueous zinc ion battery containing a redox medium provided by the present invention; Figure 2 This is a scanning electron microscope image of zinc deposition on copper foil; Figure 3 For a zinc symmetric battery at a current density of 1 mA cm -2 , areal capacity of 1 mAh cm -2 The charge and discharge test results under the conditions of; Figure 4 For a zinc symmetric cell at a current density of 5 mA cm -2 , surface capacity of 5mAh cm -2 The charge and discharge test results under the conditions of; Figure 5 This is the test result of the rate performance of aqueous zinc-ion full battery.

[0019] Icon: 1-shell; 2-positive electrode; 3-diaphragm; 4-negative electrode. DETAILED DESCRIPTION

[0020] In order to make the implementation process of the present invention clearer, it will be described in detail below with reference to the accompanying drawings.

[0021] Example 1: The present invention provides an aqueous zinc ion battery containing a redox medium, such as Figure 1As shown, the aqueous zinc-ion battery includes a housing 1, a positive electrode sheet 2, a separator 3, a negative electrode sheet 4, and an electrolyte. The positive electrode sheet 2 and the negative electrode sheet 4 are arranged at opposite ends of the housing 1. The separator 3 is arranged between the positive electrode sheet 2 and the negative electrode sheet 4. The electrolyte fills the interior of the housing 1 and contacts the positive electrode sheet 2 and the negative electrode sheet 4. The electrolyte is an aqueous solution containing zinc trifluoromethanesulfonate (Zn(CF3SO3)2), in which 10-methylphenothiazine (MPT) is dissolved.

[0022] The battery housing 1 of this embodiment utilizes a structure with upper and lower covers that fit together to form a sealed structure. The housing 1 is preferably made of polypropylene (PP) with a thickness of 0.6-1 mm. It exhibits excellent corrosion resistance, dielectric strength, and heat-sealing properties, making it suitable for long-term, stable operation in aqueous electrolyte environments. The edges of the housing 1 can be sealed using any method, such as press-fit, snap-fit, or twist-fit. Preferably, a hot-melt seal is used. This sealing method prevents electrolyte leakage while also improving the overall mechanical strength of the structure, making it suitable for energy storage device operation in temperatures between 20°C and 60°C. The interior of the housing 1 includes an inner cavity area that accommodates the electrode pads and electrolyte. The inner cavity surface is coated with a uniform insulating coating to prevent electrical shorts or side reactions caused by contact between the electrode material and the housing 1 during cycling. This coating is preferably a polyimide material with a thickness of 10-15 μm. It is applied uniformly by doctor blade or spray coating and then heat-cured to provide excellent adhesion, electrical insulation, and chemical resistance, ensuring long-term stability and resistance to peeling and expansion in electrochemical reaction environments.

[0023] The positive electrode sheet 2 and the negative electrode sheet 4 are positioned at opposite ends of the housing 1, participating in the redox reaction during the battery's charge and discharge processes, forming a three-dimensionally symmetrical electrode system. The positive electrode sheet 2 is a composite sheet, consisting of a metal substrate and an active layer. Its length and width match the housing cavity, and its thickness is preferably 100-200 μm. The metal substrate is preferably titanium foil, serving as an electron conductor and mechanical support. It is preferably 60 μm thick and suitable for aqueous high-potential positive electrode environments. The active layer, composed of manganese dioxide (MnO2), a conductive agent, and a binder, is coated on the titanium foil surface, exhibiting excellent adhesion and interfacial stability. Manganese dioxide, the primary active material, exhibits stable, reversible oxidation state transitions, enabling reversible electron transfer during the battery's charge and discharge processes. This composite structure of the positive electrode sheet 2 provides a continuous electron channel and a high specific surface area, which helps improve lateral conductivity and electron diffusion rate in the reaction zone.

[0024] The negative electrode sheet 4 is a high-purity metal zinc sheet with a thickness of preferably 80-120 μm. It is used to bear the deposition and stripping reaction of zinc ions during battery operation. The area of ​​the zinc sheet is the same as that of the positive electrode sheet 2 to ensure balanced reaction and uniform current distribution. Zinc material has a low reduction potential and can stably achieve Zn in aqueous electrolyte.2+ / Zn reversible conversion process. During the discharge stage, Zn in the electrolyte 2+ Migrate to the negative electrode and reduce and deposit as metallic zinc on the surface of the negative electrode; during the charging stage, metallic zinc is oxidized to Zn 2+ And released back into the electrolyte, completing the reversible electrochemical cycle.

[0025] The diaphragm 3 is arranged between the positive electrode sheet 2 and the negative electrode sheet 4 to achieve the dual functions of ion conduction and electronic isolation. The diaphragm 3 is made of glass fiber material with a thickness of 100-200μm and a pore size distribution in the range of 0.1-1μm. It has good structural density and chemical corrosion resistance. The surface of the diaphragm 3 has good wettability to the electrolyte and can form a continuous liquid phase channel between the positive electrode sheet 2 and the negative electrode sheet 4 to ensure the ion supply and electrolyte distribution stability of the entire reaction interface. The microporous structure of the diaphragm 3 gives it good zinc ion permeability, which helps to achieve rapid ion migration during the charge and discharge process, while inhibiting Zn 2+ The concentration shift in local areas reduces the risk of sudden changes in current density, thereby helping to improve the uniformity of zinc deposition. Its inorganic rigid skeleton can also effectively prevent growing zinc dendrites from piercing through, reducing the risk of short circuits and improving the cycle safety of the battery.

[0026] In this embodiment, the electrolyte is a composite aqueous solution located between the positive electrode sheet 2 and the negative electrode sheet 4 and is composed of Zn(CF3SO3)2 and MPT. The concentration of Zn(CF3SO3)2 is 1-3 mol / L, preferably 2 mol / L, which provides a stable zinc ion conduction foundation for the battery and also enhances the redox activity and interface regulation effect of MPT. The concentration of MPT is 1-10 mmol / L, preferably 5 mmol / L, and exists as a reversible redox pair during the electrochemical process. Its reaction behavior is as follows: Among them, MPT + In the oxidized state, MPT － In the reduced state, MPT is a neutral molecule. This redox system enables MPT to dynamically migrate between the positive and negative electrodes, and alternately act as an electron acceptor or donor during the charge and discharge process, building a stable and reversible electron buffer channel.

[0027] During the discharge phase, the MnO2 in the positive electrode 2 undergoes a reduction reaction as the main active material, and tetravalent manganese (Mn 4+ ) is reduced to trivalent manganese (Mn 3+ ), the released electrons flow to the negative electrode through the external circuit, driving the Zn 2+ The surface of the negative electrode sheet 4 is reduced and deposited as metallic zinc. At this time, the local electric field intensity on the surface of the negative electrode sheet 4 is relatively high, which easily induces the rapid growth of zinc dendrites along its normal direction.+ Capture excess electrons at the negative electrode and transform into MPT or MPT － , effectively disperse the electron density, relieve local charge accumulation, and induce Zn 2+ The metal zinc on the surface of the negative electrode 4 is oxidized to Zn 2+ And released back into the electrolyte; Mn on the surface of the positive electrode 2 3+ Oxidized to Mn 4+ At the same time, MPT － Or MPT releases electrons at the negative electrode and converts into MPT + These electrons are transported to the positive electrode to assist in the completion of the positive electrode oxidation reaction. MPT achieves electron transpolarization between electrodes through its reversible redox process, balancing electron flow, reducing polarization voltage, and regulating reaction kinetics, thereby improving the overall energy efficiency and rate performance of the battery.

[0028] Furthermore, during long-term cycling, “dead zinc” regions may appear in the negative electrode, i.e., electrochemically inactive metal zinc clusters (Zn 0 ), it is difficult to continue to participate in the reversible reaction. MPT molecules can freely diffuse to the vicinity of the "dead zinc" area in the electrolyte, and its reduced state MPT - Electrons are released through a contactless electron transfer mechanism, local charge transfer pathways are rebuilt, and the electrochemical activity of inactivated zinc clusters is restored. This mechanism establishes a diffusible electron transfer pathway that does not rely on direct contact with the current collector, effectively activating "dead zinc" and improving material utilization and cycle stability. The redox potential range of MPT is within the battery operating voltage range, and it can stably participate in electron transfer without inducing side reactions or decomposition. Its dynamically reversible electron buffering characteristics run through the entire process of zinc deposition and stripping, positive and negative electrode reaction rate matching, dendrite control, and dead zinc repair. It effectively optimizes the battery's interface behavior and cycle life without changing the main structure, and is the key control method for the present invention to achieve high-stability aqueous zinc-ion batteries.

[0029] A small-amplitude alternating voltage signal is introduced outside the battery as a dynamic electric field perturbation source to enhance the electronic regulation effect of MPT in suppressing dendrite formation. The alternating voltage signal has a frequency of 0.5-2Hz and an amplitude of 30mV. It is superimposed between the positive and negative electrodes during the battery charging and discharging process. It is controlled by an external adjustable pulse source to form a periodic electric field perturbation environment, which is used to regulate the local charge density and electric field distribution at the negative electrode interface. The voltage signal amplitude is much lower than the electrode reaction voltage and does not affect the main redox process; at the same time, it does not participate in the main reaction process, but only regulates the electric field distribution in the early stage of zinc deposition, thereby intervening in the Zn 2+The introduction of this dynamic electric field promotes the formation of more uniform initial nucleation sites on the surface of the negative electrode 4, improving the spatial deposition behavior of zinc and preventing the concentrated growth of zinc dendrites in a few high-field areas. This synergistic effect, combined with the electron buffering mechanism provided by the MPT molecules at the interface, allows the zinc deposition process to be simultaneously controlled in both electron distribution and nucleation location, ultimately resulting in a denser, smoother metallic zinc deposit, effectively enhancing the interface stability and service life during cycling.

[0030] The pH value of the electrolyte is preferably controlled between 3-5 to form a stable weakly acidic reaction environment, effectively inhibiting the hydrogen evolution side reaction and reducing the risk of interfacial gas disturbance and by-product accumulation. This pH range can also stabilize the redox potential of MPT, preventing it from irreversible decomposition or electrode desorption, thereby ensuring that it continues to play an electronic buffering role during the charge and discharge process. -2 Within the current density range, the deposition and stripping rates of zinc ions maintain a dynamic match with the electron transfer ability of MPT, enabling it to effectively participate in the electron buffering and deposition regulation process throughout the entire electrochemical cycle, thereby achieving continuous controllability and structural stability of the interfacial reaction process.

[0031] For the aqueous zinc ion battery described in this embodiment, copper foil is used as the working electrode. -2 Current density, 1mAh cm -2 After zinc was deposited under the conditions of surface capacity, the zinc deposition morphology was observed by scanning electron microscopy, such as Figure 2 shown. Figure 2 (a) is a scanning electron microscope image of the electrolyte system described in this example. It can be seen that the zinc deposited layer is dense and uniform, with no dendritic spikes on the surface and clear boundaries, indicating that the zinc deposition process is controlled with the participation of MPT and the interface stability is high. Figure 2 (b) is a scanning electron microscope image of the comparative electrolyte system. The electrolyte is a 2 mol / L aqueous solution of Zn(CF3SO3)2. The zinc deposit exhibits a distinct dendritic morphology, with a rough surface and random protrusions. This indicates a lack of an interface control mechanism, leading to localized non-uniform zinc growth and increased short-circuit risk. This shows that the electrolyte system incorporating MPT can optimize the zinc deposition morphology and inhibit dendrite formation, verifying its effectiveness in interface control and deposition behavior optimization at the microstructural level.

[0032] Example 2: Based on Example 1, in order to further improve the deposition uniformity and interface stability of the battery during long-term cycling, this example introduces two function enhancement measures: one is to add conductive nanoparticles to the electrolyte as auxiliary electron channels; the other is to coat the surface of the negative electrode 4 with polypyrrole (PPy) material to stabilize the deposition morphology.

[0033] First, conductive nanoparticles are added to the electrolyte to create an auxiliary electron pathway. Nitrogen-doped carbon quantum dots (N-CQDs) are preferred. These particles are approximately 5-10 nm in size and are rich in polar functional groups such as amino and carboxyl groups. They exhibit excellent water dispersibility and electron transport capabilities. N-CQDs are incorporated into an electrolyte containing MPT at a mass fraction of 0.02 wt% and ultrasonically dispersed for 10 minutes to form a uniform nanocomposite system. During battery operation, the N-CQDs migrate with the electrolyte and accumulate in areas with restricted interfacial electron pathways, assisting MPT in electron transport. Specifically, they establish supplementary electron pathways in "dead zinc" regions, activating locally inactive zinc. Furthermore, the carbon quantum dots themselves enhance the overall electrolyte conductivity, thereby enhancing the battery's rate capability. This conductive nanomaterial combines the dual functions of "electron bridging" and "conductance enhancement," further stabilizing the interfacial electron pathways and optimizing the local reaction environment.

[0034] Secondly, a layer of PPy material is coated on the surface of the zinc negative electrode sheet 4 to achieve stable morphology control of the deposition process. The film preparation method is as follows: a 0.1 mol / L pyrrole monomer solution is mixed with an equimolar amount of ammonium persulfate, stirred and reacted at room temperature for 30 minutes to cause oxidative polymerization of the pyrrole monomer to form a polypyrrole sol. It is evenly coated on the surface of the zinc sheet by a doctor blade method, and after drying, an interface film layer with a thickness of 10-20 μm is formed. The film layer is tightly attached to the surface of the negative electrode sheet 4, is porous and has a dense structure, and has good adhesion and flexible buffering capacity. PPy is a conductive polymer whose molecular chain has a continuous π conjugated structure, which can provide a stable electron channel in an electrochemical environment. During the charge and discharge process, the film layer allows Zn 2+ It freely penetrates and reaches the zinc metal surface, while limiting excessive zinc deposition in local areas, alleviating the tip electric field concentration effect, thereby effectively suppressing dendrite nucleation and improving deposition uniformity. Optionally, to enhance the effectiveness of MPT in the interface regulation process, a trace amount of MPT can be introduced simultaneously during the preparation of the interface film layer, resulting in local enrichment of MPT in the microporous structure of the film layer. In the initial deposition stage, this portion of MPT can achieve electron buffering and deposition induction at the negative electrode interface, enhancing the spatial uniformity of the overall reaction.

[0035] In this embodiment, the conductive nanoparticles and interfacial film are located in the electrolyte region and the negative electrode interface region, respectively. While their structural layout does not interfere with each other, their functional mechanisms complement those of the MPT, enhancing its effectiveness in regulating the electron transport chain and the deposition interface, respectively. The simultaneous introduction of these two measures helps to comprehensively improve the battery's long-cycle stability and material utilization efficiency, making it suitable for high-rate, long-life aqueous zinc-ion battery systems.

[0036] Example 3: The present invention also provides a method for preparing an aqueous zinc ion battery containing a redox medium, the method comprising the following steps: S1. Dissolve Zn(CF3SO3)2 powder in deionized water and stir to obtain a basic electrolyte. In this step, Zn(CF3SO3)2 is selected as the zinc source, which has good water solubility, conductivity and electrochemical stability and is suitable for aqueous zinc ion battery systems. Weigh 7.27g of Zn(CF3SO3)2 powder and dissolve it in 10mL of deionized water. After sufficient stirring, a basic electrolyte is formed with a concentration of 2mol / L. This concentration can provide sufficient zinc ion supply to meet the ion migration requirements at higher rates, and can also avoid interface abnormalities such as crystallization deposition caused by local supersaturation. Trifluoromethanesulfonate ion (CF3SO3 - ) is a weakly coordinating anion and is not easy to react with Zn 2+ The occurrence of stable complexation helps to improve the migration rate and reaction activity of zinc ions, further enhancing the overall kinetic properties of the electrolyte.

[0037] To ensure Zn 2+ The zinc salt is fully released and evenly distributed in the aqueous solution. This step is preferably carried out at room temperature (20-25°C) using magnetic stirring for 10-15 minutes until the resulting solution is clear and transparent with no visible suspended matter or precipitation. This operation helps to improve the dissolution efficiency of the zinc salt and stabilize the Zn in the electrolyte. 2+ The initial distribution state of the ions is optimized to reduce the risk of local concentration polarization and provide a uniform ion environment for subsequent redox reactions.

[0038] S2. Add 10-methylphenothiazine powder to the base electrolyte and dissolve it under magnetic stirring to form a redox electrolyte. Take 5 mL of the base electrolyte, add 5.33 mg of MPT powder, and magnetically stir at room temperature for 10-20 minutes until the MPT is fully dissolved and the resulting solution is light yellow and transparent with no visible precipitate or floating matter, thus preparing a redox electrolyte with a concentration of 5 mmol / L. The MPT used is a powdered raw material with an industrial purity of not less than 98%. It can be added directly to the electrolyte without pretreatment and has good solubility and redox stability, which helps improve its electronic buffering function and cyclic reversibility in the electrolyte.

[0039] MPT belongs to the phenothiazine class of compounds and possesses strong reducing properties. It is easily oxidized by oxygen in air, which affects its subsequent redox stability. Therefore, this step is preferably performed under an inert atmosphere (such as nitrogen or argon) during the addition and stirring process. This treatment effectively prevents MPT from coming into contact with oxygen during the dissolution phase, inhibiting side reactions and improving its dissolution stability and electrochemical response consistency in the electrolyte. Compared to dissolution in air, an inert atmosphere better preserves MPT's original structure and functionality, ensuring its electron transfer performance and reversibility during subsequent charge and discharge cycles.

[0040] S3. Place the positive electrode sheet 2, the diaphragm 3 and the negative electrode sheet 4 in sequence inside the shell, inject the redox electrolyte, and seal and assemble them into an aqueous zinc ion battery. The positive electrode sheet 2 and the negative electrode sheet 4 are respectively a composite electrode sheet and a metal zinc sheet, and the diaphragm 3 is a glass fiber sheet. The three constitute the basic battery unit. Place the positive electrode sheet 2 at the bottom of the battery shell 1 with the active layer facing upward; set the diaphragm 3 in the center and completely cover the positive electrode sheet 2; place the negative electrode sheet 4 on the top layer and arrange it opposite to the positive electrode sheet 2. The above three-layer components should be arranged flat and the edges should be aligned to ensure interface fit and avoid short circuits or reaction area offsets caused by component misalignment. Before assembly, the negative electrode sheet 4 can be cleaned with alcohol and lightly polished to remove its surface oxide layer and impurities, enhance its interfacial affinity with the electrolyte, and improve the uniformity and interfacial stability of the deposition reaction.

[0041] Subsequently, the redox electrolyte prepared in step S2 is dripped from multiple points on the edge of the shell 1 using a pipette and slowly injected into the battery. During the injection process, avoid direct impact of the liquid flow on the electrode surface to prevent damage to the electrode structure. The injection volume should be limited to completely wet the positive electrode sheet 2, the negative electrode sheet 4 and the diaphragm 3, and the electrolyte penetrates into the pores of the diaphragm, while avoiding liquid accumulation. After injection, the shell 1 can be slightly tilted to promote the electrolyte to spread evenly on the surface of the component, ensuring that there are no dry areas and bubbles. After the injection is completed, the battery is sealed using a hot pressing edge sealing process. The packaging temperature is controlled at 160-180°C, and the pressing time is 2-5 seconds. The specific parameters are adjusted appropriately according to the material and structure of the shell 1. The packaging process must ensure that the hot pressing position is accurate and the pressure is uniform so that the edge sealing is tightly closed to prevent liquid leakage or edge cracking. The packaged battery should be left to stand at room temperature for more than 2 hours to allow the electrolyte to be further evenly distributed and fully wetted with the electrodes, establishing a stable electrode / electrolyte interface, which is conducive to improving the repeatability and result stability of subsequent electrochemical performance tests.

[0042] In this embodiment, the steps for preparing the positive electrode sheet 2 in step S3 are as follows: MnO2 powder, conductive carbon black powder, and polyvinylidene fluoride (PVDF) binder powder were weighed and mixed in a mass ratio of 8:1:1. An appropriate amount of N-methylpyrrolidone (NMP) was added as a solvent, and stirring was continued for at least 30 minutes to form a uniform slurry. The stirring process helps promote the dissolution of PVDF and enhances its adhesion to the active material, ensuring adhesion and uniformity during the final film formation process. The slurry was evenly applied to the surface of a 60μm thick titanium foil using a doctor blade or roller coating method. The titanium foil serves as an electronic conductor and mechanical support layer, and has good corrosion resistance and interfacial stability.

[0043] After coating, let it stand for a few minutes to allow the slurry surface to initially set, which helps to reduce the risk of coating edge warping or surface cracks caused by solvent migration. Afterwards, the coated titanium foil is placed in a vacuum drying oven and dried at 100-130°C for 10-14 hours. The drying process is carried out under low-pressure vacuum conditions, which can accelerate the volatilization of the NMP solvent and inhibit the damage of the solvent residue to the bonding network structure, thereby achieving dense molding of the active layer structure. After drying, a composite electrode with firm adhesion and smooth surface is obtained. The dried composite electrode is cut according to the specifications of the battery shell to obtain a positive electrode 2 of matching size. Before assembly, the positive electrode 2 can be placed in a 60°C drying oven for a short time to dehumidify, further remove possible adsorbed moisture, reduce the thickness of the interfacial water film, help improve the electrolyte infiltration efficiency and reaction contact area, and ensure the stability and consistency of the initial cycle after assembly. In the positive electrode sheet 2 prepared by the above steps, the active components are evenly distributed and have stable adhesion, which is conducive to achieving stable reaction and efficient electron transmission of manganese-based materials, and is suitable for the aqueous zinc-ion battery manufacturing process with high consistency requirements.

[0044] The aqueous zinc-ion battery prepared in this embodiment is suitable for various application scenarios such as wearable electronic devices, portable energy storage units and distributed energy storage devices. It can meet the use requirements with high requirements for safety, cycle stability and operating life, has good environmental adaptability and system compatibility, and has broad application prospects.

[0045] Example 4: This example tests the electrochemical performance of aqueous zinc ion batteries to verify the regulation effect of the redox mediator 10-methylphenothiazine proposed in this application in aqueous zinc ion batteries. The test group battery electrolyte contains 2mol / L Zn(CF3SO3)2+5mmol / L MPT (labeled as ZF+5MPT), and the control group battery electrolyte contains only 2mol / L Zn(CF3SO3)2 basic electrolyte (labeled as ZF). The results are as follows: Figure 3-Figure 5 shown.

[0046] To accurately evaluate the impact of electrolyte differences, a CR2032 button-type half-cell was assembled for testing. The half-cell structure was a zinc symmetric cell (Zn|electrolyte|Zn). Under the same conditions, the electrolyte injection volume was 150μl, and constant current charge and discharge cycles were performed using the Xinwei CT-4008T battery test system. The termination conditions were voltage fluctuations > ±20% or short circuit failure. -2 Current density, 1mAh cm -2 Under the condition of surface capacity, the cycle voltage curve is as follows Figure 3 As shown in (a), the stable cycle of the test group battery in the figure exceeds 2800h, while the control group battery without MPT added fails due to a voltage drop (voltage fluctuation > 50%) at around 2100h, indicating that its electrode interface stability is reduced and the zinc deposition process is hindered. Figure 3 (a) It is demonstrated that the test group electrolyte with the addition of MPT can effectively improve the cycling stability of the battery, reflecting the high reversibility of its deposition / stripping process. Figure 3 (b) Figure 3 The local enlarged image of the 900-1700h interval in (a) shows that the average charge and discharge voltage of the test group in this interval increased by 39.6% compared with the control group, proving that MPT reduces interfacial impedance by inhibiting dendrite formation and activating "dead zinc". Figure 3 (c) shows a partial enlarged image of the 2225-2540h interval. In this interval, only the battery voltage of the test group remains stable, further verifying the beneficial effect of MPT on the long cycle life of the battery.

[0047] The performance of CR2032 button half-cell at high current density was further tested. -2 Current density, 5 mAh cm -2 Under the condition of surface capacity, the cycle voltage curve is as follows Figure 4 The test group batteries achieved 1000 hours of stable cycling, while the control group batteries experienced short-circuit failure around 110 hours. This result demonstrates MPT's ability to consistently regulate zinc deposition behavior, optimize electrode / electrolyte interface stability, and extend cycle life, confirming that MPT's advantages are even more pronounced at high current densities.

[0048] The full battery rate performance test of the Zn-MnO2 aqueous zinc ion battery prepared in Example 3 was performed using a Xinwei battery tester. Figure 5As shown in the figure, from top to bottom are the circular pattern curve, the left triangle pattern curve (the sharp corner of the triangle points to the left), the square pattern curve, and the right triangle pattern curve (the sharp corner of the triangle points to the right). Among them, the circular pattern curve represents the test results of the coulombic efficiency of the test group battery, and the left triangle pattern curve represents the test results of the coulombic efficiency of the control group battery; the square pattern curve represents the test results of the specific capacity of the test group battery, and the right triangle pattern curve represents the test results of the specific capacity of the control group battery. The test was cycled 40 times in total, and the current density was adjusted every 10 cycles. That is, in the 1st to 10th cycles, the current density was 0.5A g -1 (Unit: Ag -1 Indicates the current carried by unit mass of active material); for the 11th to 20th cycles, the current density is 5A g -1 ; 21st-30th cycles, current density is 2A g -1 ; 31st-40th cycles, current density is 0.5A g -1 In the figure, the coulombic efficiency of the control group battery is lower than that of the test group battery, while the coulombic efficiency of the test group is stable at nearly 100% throughout the process, indicating that the electrolyte containing MPT improves the reversibility of electron / ion transfer. -1 In the current density range, the specific capacity of the test group full battery is much higher than that of the control group full battery. In other words, the battery using the MPT electrolyte exhibits higher capacity output and lower polarization.

[0049] The above results show that by introducing MPT redox mediators into the electrolyte, the cycle life can be effectively extended, the battery capacity can be increased, and the rate response capability can be enhanced, thereby achieving a stable improvement in the overall battery performance.

[0050] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. An aqueous zinc ion battery containing a redox medium, the zinc ion battery comprising a housing, a positive electrode sheet, a separator, a negative electrode sheet and an electrolyte, wherein the positive electrode sheet and the negative electrode sheet are relatively arranged at two ends inside the housing, the separator is arranged between the positive electrode sheet and the negative electrode sheet, the electrolyte is filled in the housing and in contact with the positive electrode sheet and the negative electrode sheet, and is characterized in that: The electrolyte is an aqueous solution containing Zn(CF3SO3)2, and 10-methylphenothiazine is dissolved in the electrolyte.

2. The aqueous zinc ion battery containing a redox medium according to claim 1, wherein: The concentration of the Zn(CF3SO3)2 is 1-3 mol / L, and the concentration of the 10-methylphenothiazine is 1-10 mmol / L.

3. The aqueous zinc ion battery containing a redox medium according to claim 2, wherein: The pH value of the electrolyte is 3-5.

4. The aqueous zinc ion battery containing a redox medium according to claim 3, wherein: The positive electrode sheet is a composite electrode sheet constructed on a metal foil.

5. The aqueous zinc ion battery containing a redox medium according to claim 4, wherein: The positive electrode sheet comprises manganese dioxide material; the negative electrode sheet is made of metallic zinc material; and the separator is made of glass fiber material.

6. The aqueous zinc ion battery containing a redox medium according to claim 1, wherein: The electrolyte contains conductive nanoparticles.

7. A method for preparing an aqueous zinc ion battery containing a redox medium, characterized in that: The method comprises the following steps: S1. Dissolve Zn(CF3SO3)2 powder in deionized water and stir to obtain a basic electrolyte; S2. adding 10-methylphenothiazine powder to the basic electrolyte and dissolving it under magnetic stirring to form a redox electrolyte; S3. Arrange the positive electrode sheet, the separator and the negative electrode sheet in sequence inside the shell, inject the redox electrolyte, and seal and assemble them into an aqueous zinc ion battery.

8. The method for preparing an aqueous zinc ion battery containing a redox medium according to claim 7, wherein: In S1, the stirring temperature is 20-25°C and the stirring time is 10-15 minutes, until the solution becomes clear and transparent.

9. The method for preparing an aqueous zinc ion battery containing a redox medium according to claim 8, wherein: In S2, the 10-methylphenothiazine is added to the basic electrolyte under the protection of an inert atmosphere, and magnetic stirring is performed until it is completely dissolved.

10. The method for preparing an aqueous zinc ion battery containing a redox medium according to claim 7, wherein: In S3, the positive electrode sheet is obtained by mixing manganese dioxide, conductive carbon black and polyvinylidene fluoride in a mass ratio of 8:1:1, dispersing the mixture with N-methylpyrrolidone as a solvent, coating the mixture on a metal foil surface and drying the mixture.

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