Integrated non-alkaline gel zinc-air battery and method of manufacturing the same

Abstract

The application relates to an integrated non-alkaline gel zinc-air battery and a preparation method thereof, and belongs to the technical field of zinc-air batteries. The battery comprises a zinc negative electrode, an air positive electrode, a gel electrolyte and a packaging body. The gel electrolyte is formed by in-situ gelation of a liquid precursor containing a non-alkaline zinc salt solution and a gelling agent in the packaging body, so that an integrated close contact structure is formed between the electrode and the electrolyte. The application solves the problems of easy carbonation failure and electrode corrosion of a traditional alkaline electrolyte through a non-alkaline system, and significantly improves the long-term stability and cycle life of the battery in air. Meanwhile, the process combining liquid infusion and in-situ gelation solves the problems of poor solid-state electrolyte interface contact and easy leakage of a liquid electrolyte, realizes low interface impedance and high ion transmission efficiency. The method is simple in process, does not need a crosslinking agent, and can be completed through heating, stirring and cooling steps, is suitable for large-scale production, and has high safety and excellent electrochemical performance.

Description

Technical Field

[0001] This invention belongs to the field of zinc-air battery technology, specifically relating to an integrated non-alkaline gel zinc-air battery and its preparation method. Background Technology

[0002] Zinc-air batteries are considered a promising next-generation electrochemical energy storage device due to their high theoretical energy density, abundant and inexpensive raw materials, and environmental friendliness. However, traditional zinc-air batteries typically use strongly alkaline liquid electrolytes (such as potassium hydroxide solution), which presents the following technical challenges in practical applications:

[0003] First, liquid electrolytes are prone to leakage and volatilization, which not only leads to battery failure but also poses safety hazards, limiting battery packaging methods and application scenarios. To overcome this problem, researchers have developed gel polymer electrolytes. In existing technologies, most solutions involve gelling an alkaline electrolyte solution with a polymer matrix (such as PVA, PAA, etc.) using crosslinking agents or initiators. While this method alleviates the leakage risk to some extent, it does not change the inherent alkaline nature of the system. In the semi-open structure of air batteries, alkaline electrolytes readily react with carbon dioxide in the air to undergo carbonation, generating insoluble carbonates that clog the pores of the air positive electrode, causing catalyst deactivation and rapid degradation of battery performance. Simultaneously, the strongly alkaline environment exacerbates corrosion, passivation, and dendrite growth in the zinc negative electrode, severely restricting the battery's cycle life and coulombic efficiency.

[0004] Secondly, in terms of battery assembly technology, existing gel zinc-air batteries mostly adopt a post-stacking method, that is, the gel electrolyte, zinc anode, and air cathode are prepared separately in advance, and then physically stacked and packaged. However, this method of contacting multiple solid materials inevitably leads to problems such as poor interface contact and loose adhesion, which easily generates pores, bubbles, or uncontacted areas at the interface. These defects will lead to increased interface impedance, obstructed ion transport paths, and reduced effective reaction area, thereby causing increased internal resistance, capacity decay, and shortened lifespan of the battery. Moreover, the formation process of the gel electrolyte usually relies on the addition of additional crosslinking agents / initiators, which requires specific heating, cooling, or light conditions. The process is complex and the synthesis cycle is long, making it difficult to meet the requirements of large-scale, high-efficiency manufacturing.

[0005] It should be noted that this part of the present invention only provides background technology related to the present invention, and does not necessarily constitute prior art or known technology. Summary of the Invention

[0006] This invention provides an integrated non-alkaline gel zinc-air battery and its preparation method, which at least solves the technical problems of short cycle life and rapid performance degradation of zinc-air batteries caused by poor contact between alkaline electrolyte and stack assembly interface in the prior art.

[0007] To achieve the above objectives, in a first aspect, the present invention provides an integrated non-alkaline gel zinc-air battery, comprising a zinc negative electrode, an air positive electrode, a gel electrolyte, and a packaging body. The zinc negative electrode, the air positive electrode, and the gel electrolyte are all disposed within the packaging body, and the zinc negative electrode and the air positive electrode form an integrated, tightly contacted structure with the gel electrolyte on both sides. The gel electrolyte is formed by in-situ gelation of a liquid precursor within the packaging body, and the liquid precursor includes a non-alkaline zinc salt solution and a gelling agent dissolved therein.

[0008] Preferably, the gelling agent includes at least one of agar, gelatin, carrageenan, gellan gum, and konjac glucomannan.

[0009] Preferably, the non-alkaline zinc salt includes at least one of zinc trifluoromethanesulfonate, zinc chloride, zinc sulfate, zinc acetate, or zinc perchlorate.

[0010] Preferably, an interface buffer layer is provided between the air positive electrode and the gel electrolyte; when the liquid precursor is filled into the package, the interface buffer layer is used to prevent the liquid precursor from directly contacting the air positive electrode and generating air bubbles, and after wetting, it adheres tightly to the air positive electrode to improve interface contact.

[0011] Preferably, the interface buffer layer includes at least one of glass fiber, polyacrylonitrile, nonwoven fabric, and filter paper.

[0012] Preferably, the zinc negative electrode is wrapped with a conductive porous current collector layer; the conductive porous current collector layer is made of a conductive material that does not participate in the electrochemical reaction, and the conductive porous current collector layer is used to maintain a continuous electron conduction path when the zinc active material layer undergoes volume shrinkage or structural breakage due to reaction consumption.

[0013] Preferably, the conductive porous current collector layer is a metal mesh, which is at least one of copper mesh, titanium mesh, or stainless steel mesh.

[0014] Preferably, the current collector for the positive air electrode is a titanium mesh, nickel mesh, copper mesh, or stainless steel mesh.

[0015] Preferably, the packaging body has ventilation holes in the area corresponding to the positive air electrode.

[0016] In a second aspect, the present invention provides a method for preparing the integrated non-alkaline gel zinc-air battery of the first aspect, comprising the following steps:

[0017] Step S102: Mix the gelling agent with the non-alkaline zinc salt solution and heat and stir to form a homogeneous liquid precursor;

[0018] Step S104: Place the zinc negative electrode and the air positive electrode into the packaging body and partially seal them, leaving a filling port;

[0019] Step S106: Inject the liquid precursor prepared in step S102 into the packaging body through the filling port, so that it covers the zinc negative electrode and is in close contact with the air positive electrode.

[0020] Step S108: Seal the filling port and allow the liquid precursor to cool and gel in situ within the packaging to form an integrated non-alkaline gel zinc-air battery.

[0021] Preferably, the heating and stirring in step S102 includes a mixing stage: maintaining stirring at a temperature of 115°C to 120°C and a rotation speed of 600 rpm to 800 rpm for 10 to 15 minutes to allow the gelling agent to completely dissolve in the non-alkaline zinc salt solution to form a liquid precursor.

[0022] Preferably, after the mixing stage, a defoaming stage is also included: the liquid precursor is cooled and the rotation speed is reduced in stages until it is stirred at a temperature of 95°C to 99°C and a rotation speed of 200 rpm to 300 rpm for 5 to 10 minutes to eliminate bubbles.

[0023] Preferably, in step S102, the mass ratio of the gelling agent to the volume of the non-alkaline zinc salt solution is (0.1g~0.7g):10mL.

[0024] Preferably, the concentration of the non-alkaline zinc salt solution is 0.1M to 0.5M.

[0025] Preferably, in step S106, the injection time of the liquid precursor is 1 min to 2 min.

[0026] Preferably, in step S108, the cooling is natural cooling.

[0027] The beneficial effects of this invention are as follows:

[0028] This invention successfully constructs an integrated non-alkaline gel zinc-air battery by combining a non-alkaline zinc salt solution with a gelling agent and employing a unique liquid precursor infusion and in-situ gelation process. The technical solution of this invention fundamentally solves the technical problems of traditional alkaline zinc-air batteries, such as electrode failure, electrolyte leakage, and poor contact between the solid electrolyte and electrode interface caused by carbonation. Specifically, the non-alkaline gel electrolyte system effectively avoids the reaction with carbon dioxide in the air to form carbonates, significantly improving the long-term chemical stability of the battery in air, inhibiting corrosion and dendrite growth of the zinc anode, thereby greatly extending the battery's cycle life. This invention achieves in-situ formation of the electrolyte between the electrodes by directly injecting the liquid precursor into the pre-packaged battery and cooling and solidifying it. This ensures a bubble-free, gap-free, integrated, and tightly contacted interface between the gel electrolyte, the zinc anode, and the air cathode, greatly reducing interface impedance, improving ion transport efficiency and reaction uniformity, and thus enhancing the battery's capacity output, power density, and zinc utilization. Furthermore, this preparation process does not require additional crosslinking agents or initiators and can be completed through simple steps such as heating, stirring, and natural cooling. The process is simple, efficient, and suitable for large-scale production, while also possessing high safety and good electrochemical performance. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a flowchart illustrating the preparation method of the integrated non-alkaline gel zinc-air battery provided in Embodiment 1 of the present invention.

[0031] Figure 2 The graph shows the test results of ionic conductivity of Zn(OTf)2 solutions of different concentrations.

[0032] Figure 3 Optical photographs of AG electrolytes prepared from Zn(OTf)2 solutions of different concentrations.

[0033] Figure 4 The graph shows the mechanical strength test results of the AG electrolyte of this invention.

[0034] Figure 5 This is a schematic diagram showing the relationship between the mechanical strength and solidification time of AG electrolytes corresponding to Zn(OTf)2 solutions of different concentrations according to the present invention.

[0035] Figure 6The graph shows the ionic conductivity and electrochemical window test results of the AG electrolyte prepared in Example 1.

[0036] Figure 7 The graph shows the water absorption test results for AG polymer and AG electrolyte.

[0037] Figure 8 The image shows the SEM microstructure of the AG electrolyte.

[0038] Figure 9 This is a schematic diagram of the interfacial reactions between the AG electrolyte and the air positive electrode and the zinc negative electrode, respectively.

[0039] Figure 10 Optical image of the interface between AG electrolyte and zinc anode.

[0040] Figure 11 The image shows the XRD pattern of the air cathode in the AG electrolyte system after charging and discharging.

[0041] Figure 12 1mA·cm -2 Schematic diagram of the reaction mechanism at different charge and discharge depths of the air cathode under different current densities.

[0042] Figure 13 XRD patterns of zinc anodes immersed in liquid electrolyte (Comparative Example 2) and AG electrolyte (Example 1) for 15 days.

[0043] Figure 14 SEM and optical images of zinc anodes immersed in liquid electrolyte (Comparative Example 2) and AG electrolyte (Example 1) for 15 days.

[0044] Figure 15 The graph shows a comparison of the long-term cycling performance of zinc-zinc symmetric batteries in liquid electrolyte (Comparative Example 2) and AG electrolyte (Example 1).

[0045] Figure 16 A confocal microscope image of the zinc anode of a zinc-zinc symmetric battery after 100 hours of cycling in a liquid electrolyte (Comparative Example 2).

[0046] Figure 17 A confocal microscope image of the zinc anode of a zinc-zinc symmetric battery after 100 hours of cycling in an AG electrolyte (Example 1).

[0047] Figure 18 The graph shows the discharge performance versus zinc utilization (ZUR) of the integrated pouch cell prepared in Example 1.

[0048] Figure 19 The integrated pouch cell prepared for Example 1 was tested at 0.1 mA·cm⁻¹. -2 Long-cycle performance at current density. Detailed Implementation

[0049] In this invention, unless otherwise stated, directional terms such as "upper," "lower," "left," and "right" generally refer to the orientation shown in conjunction with the accompanying drawings and in practical application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0050] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0051] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0052] The terms "optional" and "optional" both mean that they may or may not be included (or may or may not be present).

[0053] In a first aspect, the present invention provides an integrated non-alkaline gel zinc-air battery, comprising a zinc negative electrode, an air positive electrode, a gel electrolyte, and a packaging body. The zinc negative electrode, the air positive electrode, and the gel electrolyte are all disposed within the packaging body, and the zinc negative electrode and the air positive electrode form an integrated, tightly contacted structure with the gel electrolyte on both sides. The gel electrolyte is formed by in-situ gelation of a liquid precursor within the packaging body. The liquid precursor includes a non-alkaline zinc salt solution and a gelling agent dissolved therein.

[0054] Understandably, traditional zinc-air batteries often use alkaline liquid electrolytes, which readily react with carbon dioxide in air to form carbonates, clogging the pores of the air positive electrode and leading to catalyst deactivation and battery performance degradation. Simultaneously, liquid electrolytes pose a leakage risk, limiting battery packaging methods and application scenarios. This invention solves the carbonation problem by using a non-alkaline zinc salt solution, significantly improving the battery's long-term stability in air. Furthermore, through in-situ gelation of the gelling agent, the electrolyte transforms from a liquid to a gel state inside the battery, not only eliminating the leakage risk but also achieving an integrated, tight-contact structure between the electrode and electrolyte, effectively reducing interfacial impedance and improving ion transport efficiency. This integrated structure ensures that the gel electrolyte fully fills the battery interior, coating the zinc negative electrode and forming a tight contact interface with the air positive electrode, avoiding the pores, bubbles, and uncontacted areas caused by poor contact between the solid electrolyte and electrode in traditional stacking methods, thereby improving battery capacity output and cycle life.

[0055] More specifically, the technical solution of this invention is a synergistic solution addressing the chemical, physical, and process defects existing in the prior art. First, at the level of chemical defects, traditional zinc-air batteries rely on strongly alkaline electrolytes (such as KOH solution). However, zinc-air batteries are inherently semi-open structures, requiring the air cathode to be in contact with the outside air to obtain oxygen as a reactant. This leads to unavoidable carbonation problems, as strongly alkaline electrolytes readily absorb carbon dioxide from the air (e.g., the reaction 2KOH + CO2 → K2CO3 + H2O occurs). The generated insoluble carbonates such as K2CO3 or ZnCO3 physically block the porous structure of the air cathode, hindering the effective electrochemical reaction and causing rapid performance degradation. Simultaneously, the strongly alkaline environment exacerbates hydrogen evolution corrosion, passivation (generating ZnO / Zn(OH)2), and dendrite growth problems in the zinc anode, severely limiting the battery's cycle life.

[0056] Secondly, at the level of physical defects, existing technologies for gel or solid electrolytes developed to address liquid electrolyte leakage generally employ a post-assembly stacking method. This involves physically stacking and encapsulating pre-prepared solid electrolyte membranes with solid zinc anodes and solid air cathodes. This physical contact at the solid interface is inherently uneven and loose. At the microscopic level, pores, bubbles, or uncontacted areas inevitably form between the two solid surfaces. Furthermore, slippage may occur at the two contact interfaces during assembly, leading to poor contact and a reduction in the effective reaction area. These physical defects result in obstructed ion transport paths, a sharp increase in interfacial impedance, and a decrease in the effective reaction area, ultimately leading to increased internal resistance, capacity decay, and shortened battery life.

[0057] Third, regarding process defects, the existing strategies for in-situ synthesis of gel electrolytes (such as PVA and PAA systems) typically rely on additional crosslinking agents or initiators for the gelation process, and require specific heating, cooling, or light conditions, resulting in complex processes and synthesis cycles ranging from several hours to several days.

[0058] To address the aforementioned triple defects, this invention employs a non-alkaline zinc salt solution. Non-alkaline systems exhibit excellent chemical stability in air and do not undergo carbonation with CO2. This ensures the long-term operational stability of the air cathode and better suppresses side reactions in the zinc anode. This invention utilizes in-situ gelation of a liquid precursor within the packaging, with the core process employing liquid filling and in-situ curing. During filling, the excellent fluidity and wettability of the liquid precursor allow it to penetrate and fully fill every tiny gap, corner, and electrode pore within the flexible packaging, completely wetting and coating the electrode surfaces (including the zinc anode and air cathode). This invention forms a monolithic, tightly contacted structure. After the liquid precursor gels in situ within the packaging, the interface formed in the liquid phase is locked. This ultimately results in a bubble-free, gap-free, and slip-free monolithic, tightly contacted structure. This structure ensures the lowest interfacial impedance and a highly efficient ion transport network, enabling high capacity and long lifespan. This invention uses a gelling agent with the physical properties of thermal dissolution and condensation. Its gelation process does not require the driving force of crosslinking agents / initiators; a rapid transition from liquid to gel state can be achieved through simple physical steps of heating and cooling. This makes the process of this invention extremely simple, efficient, low-cost, and easy to scale up for production.

[0059] In summary, the technical solution of this invention is a complete system that combines a non-alkaline chemical system, an integrated physical interface, and a simplified hot-melt condensation process, which together solve the technical problems of carbonation failure, poor interface contact, and process complexity that cannot be overcome simultaneously by existing technologies.

[0060] Preferably, the gelling agent includes at least one selected from agar, gelatin, carrageenan, gellan gum, and konjac glucomannan. More preferably, the gelling agent is agar.

[0061] Understandably, these gelling agents are chosen because they possess the properties of dissolving upon heating and solidifying upon cooling, enabling rapid gelation without the need for crosslinking agents or initiators. Agar, a natural polysaccharide, exhibits high gel strength and the characteristic of dissolving upon heating and solidifying rapidly upon cooling, making it suitable for rapid liquid-solid transitions in in-situ filling. Furthermore, it has excellent compatibility with zinc salt solutions, making it one of the preferred gelling agents. Gelatin and carrageenan also possess similar properties of dissolving upon heating and solidifying upon cooling, and are widely available and inexpensive, allowing for selection or compounding based on specific needs. These gelling agents form a uniform liquid precursor upon heating, facilitating filling and packing. Upon cooling, they form a stable three-dimensional network structure, effectively immobilizing the electrolyte solution and preventing leakage, while also providing continuous channels for ion migration. Moreover, when combined with non-alkaline zinc salt solutions, they can suppress water activity and side reactions, further enhancing the electrochemical stability and safety of the battery.

[0062] More specifically, the gelling agent of this invention is the material basis for realizing the integrated construction process and excellent electrochemical performance of this invention. The reason for choosing this type of material lies in its physical properties of thermal dissolution and condensation. Taking agar (AG) as an example, the gelation of agar is a physical process. When heated (e.g., above 100°C), the double helix structure of the agar polymer chains unwinds and dissolves in a non-alkaline zinc salt solution, forming a low-viscosity, easily flowing liquid precursor (i.e., sol state). When naturally cooled, the agar chain segments re-entangle and aggregate through non-covalent forces such as hydrogen bonds, forming a stable three-dimensional network (crosslinking) structure, thereby physically locking the liquid electrolyte solution within the network, forming a gel state. This process does not require chemical driving by crosslinking agents or initiators, matching the integrated construction process of this invention that combines liquid infusion and in-situ solidification.

[0063] This gel electrolyte, formed from a gelling agent (using agar as an example), offers the following technical advantages: First, traditionally, it is believed that the ionic conductivity of gel electrolytes is less than 50% of that of liquid electrolytes. However, this invention overcomes this deficiency through material and process optimization, achieving an ionic conductivity of approximately 70% that of liquid electrolytes. The possible mechanism lies in the strong water absorption of the pure agar polymer matrix (AG polymer), which can absorb nearly 20 times its own weight in water. After being prepared into an AG electrolyte (containing zinc salts), it can also store more than 5 times its own weight in electrolyte. The gelled AG electrolyte exhibits a highly cross-linked structure and abundant channels. This three-dimensional network structure physically binds a large amount of electrolyte, while its abundant internal channels are for zinc ions (Zn). 2+ The rapid migration of ) provides a low-resistance pathway.

[0064] Secondly, agar, as a natural polysaccharide, is rich in hydroxyl (-OH) polar groups on its molecular chain. These hydroxyl groups bind tightly to water molecules in the electrolyte through strong hydrogen bonds. This strong interaction greatly limits the amount and activity of water. In the electrochemical system, the activity of water is effectively reduced, which can significantly reduce the hydrogen evolution corrosion (HER) side reaction (2H₂O + 2e⁻) on the zinc anode surface. - →H2+2OH - This improves the coulombic efficiency and stability of zinc. Simultaneously, because the activity of water is suppressed, the interfacial flux of zinc ions during the deposition process is more uniform, thus achieving dendrite-free zinc deposition.

[0065] In summary, the gelling agent (such as agar) of this invention not only provides processability for liquid infusion and in-situ solidification processes, but more importantly, its unique chemical structure (such as the hydroxyl groups of agar) regulates interfacial chemistry at the microscopic level through water-binding activity, achieving a high degree of suppression of hydrogen evolution, dendrites, and byproducts, thereby maintaining the reaction stability of the positive and negative electrode interfaces, effectively suppressing side reactions, and enhancing reaction stability and reversibility. This invention is not limited to agar; other polymers with similar thermally reversible gel properties and / or rich in functional groups such as hydroxyl groups, such as gelatin, carrageenan, gellan gum, and konjac glucomannan, as long as they can achieve or partially achieve the synergistic effects of the above-mentioned process simplicity, high conductivity, and interfacial stability, should all fall within the protection scope of this invention.

[0066] Preferably, the non-alkaline zinc salt includes at least one of zinc trifluoromethanesulfonate, zinc chloride, zinc sulfate, zinc acetate, or zinc perchlorate. More preferably, the non-alkaline zinc salt is zinc trifluoromethanesulfonate.

[0067] Alternatively, these non-alkaline zinc salts possess high solubility and ionic conductivity, enabling them to form stable electrolyte solutions in water and avoiding the susceptibility to carbon dioxide reactions seen in alkaline electrolytes. By using non-alkaline zinc salt systems, the chemical stability of the battery during long-term operation in air is significantly enhanced, while the formation of a gel electrolyte further reduces water activity, lowering the risk of hydrogen evolution corrosion and byproduct accumulation.

[0068] Furthermore, in strongly alkaline systems, the thermodynamic instability of the zinc anode itself leads to severe hydrogen evolution corrosion and passivation. In contrast, non-alkaline systems (especially near-neutral systems) can significantly suppress these side reactions, improving the utilization efficiency and cycle stability of the zinc anode.

[0069] It is understood that zinc trifluoromethanesulfonate (Zn(OTf)₂) is a preferred choice in this invention. Zn(OTf)₂ has high solubility and high dissociation in aqueous solution, providing abundant charge carriers, which is the chemical basis for achieving high ionic conductivity. Trifluoromethanesulfonate (OTf) -Zinc(II) is a highly stable noncoordinate anion with extremely weak coordination ability and a wide electrochemical window. This makes the electrolyte itself less prone to oxidation or reduction side reactions on the electrode surface, improving the electrochemical stability of the entire system. This system can effectively inhibit the corrosion and dendrite growth of the zinc anode.

[0070] Other salts such as zinc chloride (ZnCl2), zinc sulfate (ZnSO4), zinc acetate (Zn(OAc)2), or zinc perchlorate (Zn(ClO4)2) are also viable non-basic zinc salts, all of which can avoid the carbonation problem. For example, ZnSO4 and ZnCl2 are more cost-effective and have advantages in industrial applications, but more precise control may be needed in specific applications to suppress their anions (such as Cl-). - It may cause slight corrosion or side effects.

[0071] Understandably, the non-alkaline system also achieves a highly reversible cathode reaction. In the zinc trifluoromethanesulfonate system, a stable and reversible Zn / ZnO2 reaction occurs at the air cathode, rather than the complex, multi-step oxygen reduction (ORR) reaction with poor reversibility found in the alkaline system.

[0072] Understandably, the gelling agent and non-alkaline zinc salt work synergistically. The non-alkaline zinc salt provides a macroscopic environment characterized by no carbonation, a wide electrochemical window, and chemical stability. The gelling agent, through its hydroxyl groups binding water activity, inhibits hydrogen evolution and dendrite formation, providing physicochemical regulation of the microscopic interface. It is precisely this combination of macroscopic chemical environment (non-alkaline) and microscopic interface regulation (gel water locking) that jointly achieves the suppression of hydrogen evolution, dendrite formation, and byproducts (such as basic salts), enabling the battery to achieve excellent stability.

[0073] Understandably, the choice of a non-alkaline zinc salt solution is not only for electrochemical stability considerations, but also a prerequisite for ensuring successful in-situ gelation of the gelling agent. In traditional strongly alkaline environments (such as high-concentration KOH solutions), the gelation ability of the gelling agent is severely inhibited or even fails. The underlying reason may be that a strongly alkaline environment interferes with non-covalent bonding interactions such as hydrogen bonds between the gelling agent's molecular chains. These forces are the basis for its formation of a three-dimensional network structure through heating to dissolve, cooling, and reassembling. Alkalinity disrupts its thermally reversible physical gelation properties, causing the liquid precursor to fail to solidify upon cooling, or resulting in an extremely fragile and unstable gel structure.

[0074] Meanwhile, it should be noted that the concentration of the non-alkaline zinc salt should not be too high. Excessive zinc salt concentration may also adversely affect the gelation process. Therefore, the non-alkaline zinc salt system of this invention provides a macroscopic chemical environment with no carbonation and a wide electrochemical window. Simultaneously, controlling the zinc salt concentration within a suitable range provides the necessary physicochemical environment for the gelling agent to exert its inherent, cross-linking-free, hot-melt-cooling properties, thereby ensuring that the liquid precursor can smoothly and stably complete in-situ gelation within the battery packaging. The synergistic effect of the non-alkaline chemical system and the hot-melt-cooling gelation process jointly guarantees the implementation of the integrated battery technology solution of this invention.

[0075] Preferably, an interface buffer layer is provided between the air positive electrode and the gel electrolyte; when the liquid precursor is filled into the package, the interface buffer layer is used to prevent the liquid precursor from directly contacting the air positive electrode and generating air bubbles, and after wetting, it adheres tightly to the air positive electrode to improve interface contact.

[0076] Understandably, the core process of this invention involves injecting a hot liquid precursor (temperature between 95°C and 99°C) into a pre-packaged battery pack at room temperature. During the injection of the gel electrolyte precursor, numerous bubbles appear when the hot gel electrolyte comes into contact with the carbon cathode. The possible causes of these bubbles include the combined effect of thermal shock and abrupt changes in surface tension. The active material of the air cathode (such as nano-carbon powder) has a porous structure with a high specific surface area. When a hot, viscous liquid precursor suddenly impacts the surface of the porous carbon cathode at room temperature, the air (or solvent vapor) originally present in the pores of the carbon layer expands rapidly due to heat, making it difficult to escape; simultaneously, the surface tension of the liquid leads to uneven wetting, thus trapping a large number of microbubbles at the interface. These bubbles trapped at the interface form voids or uncontacted areas after the electrolyte cools and gels. This directly leads to a sharp increase in interfacial impedance on the cathode side and a drastic reduction in the effective reaction area (three-phase interface), causing the battery's electrochemical performance (capacity and rate performance) to fall far short of expectations.

[0077] Understandably, the interface buffer layer of this invention first acts as a physical barrier, preventing the direct impact of the high-temperature liquid precursor on the carbon cathode. Then, after being wetted during the filling process, the interface buffer layer can adhere tightly to the carbon layer. The liquid precursor first slowly and uniformly wets the buffer layer. The buffer layer, through its own capillary force, conducts or guides the liquid electrolyte to the surface of the carbon cathode. This process is gradual, rather than impactful, thus effectively and gently expelling the air originally present in the pores of the carbon cathode, avoiding the formation and trapping of bubbles. By setting the interface buffer layer, the residual bubbles at the cathode interface are effectively avoided, thereby ensuring the formation of a low-resistance, high-effective-reaction-area, integrated, tight-contact interface between the gel electrolyte and the air cathode. This is one of the keys to achieving high battery capacity and long cycle life.

[0078] Preferably, the interface buffer layer comprises at least one of glass fiber, polyacrylonitrile (PAN), nonwoven fabric, and filter paper. To achieve the above functions, the present invention preferably uses materials such as glass fiber, PAN, nonwoven fabric, or filter paper as the interface buffer layer. The interface buffer layer should possess the following characteristics: First, good wettability, capable of being rapidly and uniformly wetted by high-temperature liquid precursors; Second, porous structure, capable of adsorbing and retaining electrolytes and acting as ion conduction channels; Third, chemical and thermal stability, remaining stable in non-alkaline zinc salt systems and at the filling temperature (99°C), without degradation or reaction; Fourth, flexibility, capable of closely adhering to the surface microstructure of the carbon cathode.

[0079] Preferably, the zinc negative electrode is wrapped with a conductive porous current collector layer; the conductive porous current collector layer is made of a conductive material that does not participate in the electrochemical reaction, and the conductive porous current collector layer is used to maintain a continuous electron conduction path when the zinc active material layer undergoes volume shrinkage or structural breakage due to reaction consumption.

[0080] It is understood that the conductive porous current collector structure of this invention is designed to address the physical defects of the zinc anode during discharge (consumption) and achieve high zinc utilization rate (ZUR). In this system, zinc itself is a negative electrode reactant; during battery discharge, zinc metal is continuously oxidized and consumed (Zn→Zn). 2+ +2e - Meanwhile, the reaction zone of zinc is not uniform or synchronous. Therefore, as the reaction proceeds (zinc is continuously consumed), traditional zinc foil (if used directly as the negative electrode and current collector) will experience intermediate or localized fractures due to volume shrinkage or uneven corrosion, even leading to the breakage of the tabs connecting to the external circuit. Once a physical fracture occurs, although the zinc metal at the rear end of the fractured part still exists, it has lost its electronic conduction path to the external circuit. This results in a significant reduction in battery capacity, which is one of the core reasons for the low zinc utilization rate of traditional zinc-based batteries (especially soft-pack batteries using zinc foil).

[0081] This invention employs a conductive porous current collector layer to encapsulate the zinc anode. This current collector layer acts as a three-dimensional electronic framework. It does not participate in the reaction within the system, but merely serves as a current collector. It tightly encapsulates the zinc foil and is completely enveloped by the electrolyte after injection. In this configuration, even if the internal zinc anode (active material) undergoes volume shrinkage or structural breakage due to consumption, the non-reactive conductive framework maintains its structural integrity and conductive continuity. This structure ensures that any remaining, even isolated, zinc active material can still maintain effective electronic communication with the external circuit through the current collector layer. This allows the reaction to proceed continuously at any time until the zinc anode is completely depleted.

[0082] Preferably, the conductive porous current collector layer is a metal mesh, which is at least one of copper mesh, titanium mesh, or stainless steel mesh.

[0083] Understandably, the conductive porous current collector layer should be made of a conductive material that does not participate in the electrochemical reaction. It should also possess porous characteristics, allowing the gel electrolyte precursor to fully permeate during infusion, achieving complete encapsulation of the zinc active material by the electrolyte, and ensuring that both the electrolyte (ion channel) and the current collector (electron channel) reach all active materials simultaneously. Copper mesh is a preferred choice due to its excellent conductivity and low cost. Titanium or stainless steel mesh are also viable alternatives, as they may offer stronger corrosion resistance in certain electrolyte environments.

[0084] Preferably, the current collector for the positive air electrode is a titanium mesh, nickel mesh, copper mesh, or stainless steel mesh.

[0085] Understandably, the air cathode needs to be connected to the outside air to achieve the reduction and evolution of oxygen; therefore, the current collector must have good conductivity and corrosion resistance. Materials such as titanium mesh and nickel mesh exhibit high stability in non-alkaline environments and can bond well with the carbon cathode, making them preferred options.

[0086] Preferably, the packaging body has ventilation holes in the area corresponding to the positive air electrode.

[0087] Understandably, vents are placed on the positive electrode side of the packaging to ensure smooth airflow and prevent the positive electrode reaction from being limited by oxygen deficiency. The number and size of the vents can be adjusted according to the battery power and packaging form to balance air supply and packaging reliability.

[0088] Preferably, the packaging material includes, but is not limited to, plastic, plastic shell, aluminum-plastic film, acrylic sheet, metal product packaging, etc.

[0089] Understandably, as the physical shell and structural carrier of the battery, the packaging material selection must be compatible with the unique liquid filling, in-situ gelation process, and non-alkaline gel system of this invention to ensure the battery's encapsulation reliability, process feasibility, and final performance. This invention is not limited to a single packaging material but provides multiple options to adapt to different application scenarios, cost requirements, and performance priorities. The technology of this invention has broad applicability and industrialization potential.

[0090] In a second aspect, the present invention provides a method for preparing an integrated non-alkaline gel zinc-air battery as described in the first aspect, comprising the following steps:

[0091] Step S102: Mix the gelling agent with the non-alkaline zinc salt solution and heat and stir to form a homogeneous liquid precursor;

[0092] Step S104: Place the zinc negative electrode and the air positive electrode into the packaging body and partially seal them, leaving a filling port;

[0093] Step S106: Inject the liquid precursor prepared in step S102 into the packaging body through the filling port, so that it covers the zinc negative electrode and is in close contact with the air positive electrode.

[0094] Step S108: Seal the filling port and allow the liquid precursor to cool and gel in situ within the packaging to form an integrated non-alkaline gel zinc-air battery.

[0095] Understandably, this method achieves in-situ formation and integrated construction of the electrolyte by directly injecting the liquid precursor into the pre-encapsulated battery and then cooling and solidifying it, fundamentally solving the problems of poor interfacial contact and complex processes in traditional stacking methods. In step S102, heating and stirring ensure that the gelling agent is completely dissolved and mixed uniformly, providing a precursor with good flowability for subsequent filling. In step S104, the design of partial encapsulation and reserved filling port facilitates electrolyte filling and subsequent encapsulation. In step S106, the flowability and wettability of the liquid precursor allow it to fully fill the electrode gaps, coat the zinc anode, and maintain close contact with the air cathode. In step S108, the cooling gelation process transforms the electrolyte from a liquid state to a gel state, forming a stable interfacial structure. The entire process requires no crosslinking agent or initiator, and can be completed solely through heating and cooling, simplifying the process, improving production efficiency, and making it suitable for large-scale applications.

[0096] Preferably, the heating and stirring in step S102 includes a mixing stage: maintaining stirring at a temperature of 115°C to 120°C and a rotation speed of 600 rpm to 800 rpm for 10 to 15 minutes to allow the gelling agent to completely dissolve in the non-alkaline zinc salt solution to form a liquid precursor.

[0097] Preferably, after the mixing stage, a defoaming stage is also included: the liquid precursor is cooled and the rotation speed is reduced in stages until it is stirred at a temperature of 95°C to 99°C and a rotation speed of 200 rpm to 300 rpm for 5 to 10 minutes to eliminate bubbles.

[0098] Optionally, high-temperature, high-speed stirring during the mixing stage ensures rapid dissolution of the gelling agent and system homogeneity, but it may also introduce air bubbles, affecting subsequent filling quality. The defoaming stage, by gradually reducing the temperature and rotation speed, allows air bubbles to escape slowly, avoiding residual bubbles caused by drastic cooling or stirring. This staged control process significantly improves the uniformity and fillability of the precursor, which is crucial for obtaining a defect-free gel electrolyte. If the defoaming stage is skipped or the parameters are not properly controlled, residual air bubbles in the precursor will form pores after solidification, leading to poor interfacial contact and decreased battery performance.

[0099] Furthermore, the goal of step S102 is to prepare a uniform, bubble-free, pourable liquid precursor. High temperature and high rotation speed are required to rapidly dissolve and homogenize the agar. However, such high temperature and high rotation speed may cause the solution to boil and generate a large number of bubbles. Due to the presence of these numerous bubbles, electrolyte pouring is impossible. If this bubble-filled precursor is forcibly poured, these bubbles will be trapped inside the gel electrolyte and at the electrode interface after cooling in S108, forming numerous pore defects.

[0100] This invention utilizes a controlled two-stage process to obtain a uniform and bubble-free liquid precursor. In the mixing stage, the temperature is above the melting point of agar to ensure rapid and complete dissolution of the agar powder, fully dissociating its polymer chains to form a homogeneous sol. The rotational speed in this stage provides sufficient shear force to rapidly disperse the agar powder upon addition to the solution, preventing clumping. Maintaining sufficient stirring time is crucial to ensure adequate time for this dissolution and homogenization process; too short a time may lead to incomplete dissolution of the gelling agent or an uneven system, directly affecting the quality and performance of the subsequent gel.

[0101] During the defoaming stage, the temperature is below the boiling point of water, causing the solution to stop boiling and preventing the generation of new bubbles. It is also above the gelation temperature of agar to ensure that the precursor remains liquid and has good flowability throughout the defoaming and subsequent filling process. The rotation speed can be reduced to stop high-speed shearing, preventing the entrainment of new air. Slow stirring prevents localized gelation or crusting due to uneven surface heat dissipation, maintaining a uniform system temperature. Slight disturbance helps accelerate the rise and escape of existing bubbles. Maintaining an appropriate stirring time provides an optimized time window for the rise and escape of existing bubbles. This duration ensures that most macroscopic bubbles are effectively eliminated, resulting in a clear precursor suitable for filling, while avoiding excessively long process times, meeting the efficiency requirements of large-scale production.

[0102] Preferably, the present invention proceeds gradually and in stages from the mixing stage to the defoaming stage, for example, adjusting from 120°C, 800 rpm to 110°C, 500 rpm, and then to 99°C, 300 rpm.

[0103] Understandably, this phased reduction of temperature and rotation speed is a creative optimization to achieve the high uniformity and low bubble content required during mixing of the specific system of this invention (gelling agent + non-alkaline zinc salt).

[0104] More specifically, during the mixing stage (e.g., 120°C, 800 rpm), the system is in a state of violent motion and boiling, containing a large number of bubbles. Directly reducing this high-temperature, high-momentum system to the target defoaming conditions (e.g., 99°C, 300 rpm) would be equivalent to subjecting the system to a severe thermal and mechanical shock. This would cause the liquid viscosity to increase rapidly with the sudden drop in temperature, trapping a large number of small bubbles that haven't yet escaped within the liquid and preventing them from rising to the surface and bursting. Simultaneously, the drastic and unstable cooling could lead to localized supersaturation, triggering even more intense gas-liquid exchange, which is detrimental to obtaining a stable and homogeneous precursor.

[0105] Therefore, setting one or more intermediate transition stages (such as 110°C, 500 rpm) is crucial. This process acts as a buffer, slowly lowering the temperature to allow the solution to move away from boiling, stopping the generation of new steam bubbles and creating a stable thermal environment for the escape of existing bubbles. Slowly reducing the rotation speed reduces the shear force of the fluid, preventing strong eddies from breaking large bubbles into more difficult-to-remove microbubbles, while also mitigating surface fluctuations and providing calm surface conditions for bubble rise and collapse.

[0106] Preferably, in step S102, the mass ratio of the gelling agent to the volume of the non-alkaline zinc salt solution is (0.1g~0.7g):10mL, which can be 0.1g:10mL, 0.2g:10mL, 0.3g:10mL, 0.4g:10mL, 0.5g:10mL, 0.6g:10mL, 0.7g:10mL, and any value between them.

[0107] Understandably, the ratio of gelling agent to solution directly affects the flowability, gel strength, and curing time of the precursor. Too low a ratio will result in insufficient gel strength, prolonged curing time, and difficulty in forming a stable coating layer; too high a ratio will result in excessively high precursor viscosity, poor flowability, and difficulties in pouring and interfacial wetting.

[0108] The ratio (i.e., the mass fraction of agar) directly determines the viscosity of the liquid precursor (which in turn affects flowability and fillability) and the mechanical strength of the solidified gel (which in turn affects its support for the electrodes). When the ratio is too low, although gel electrolytes can still be synthesized, it takes a relatively long time to solidify, which reduces cooling efficiency; and the gel is too soft, its mechanical strength will decline, and it cannot effectively support the electrodes when the pouch cell is bent or squeezed, which can easily lead to damage to the internal structure or short circuits between the electrodes. When the ratio is too high, too much agar powder will reduce the flowability of the electrolyte precursor (i.e., the viscosity is too high), which will make it difficult to achieve the filling process (the viscosity is too high, making it difficult to inject through the filling port); even if injected, the high viscosity liquid is not conducive to good interfacial contact (it cannot fully wet the microporous structure of the electrodes).

[0109] More preferably, in step S102, the ratio of the mass of the gelling agent to the volume of the non-alkaline zinc salt solution is 0.5 g: 10 mL, which is a balance between suitable fluidity (facilitating pouring), good mechanical strength (supporting the battery), and reasonable curing time.

[0110] Preferably, the concentration of the non-alkaline zinc salt solution is 0.1M to 0.5M, and can be 0.1M, 0.2M, 0.3M, 0.4M, 0.5M, or any value between them.

[0111] Understandably, the concentration of non-alkaline zinc salt solutions affects ionic conductivity and electrochemical performance. Too low a concentration results in slow ion migration and high internal resistance, while too high a concentration may lead to crystallization or decreased compatibility with the gelling agent. By optimizing the ratio and concentration, a balance can be achieved between high ionic conductivity, good mechanical strength, and suitable curing time, ensuring that the battery possesses both high electrochemical performance and structural stability.

[0112] The concentration of the non-alkaline zinc salt solution directly determines the carrier concentration in the electrolyte, thus affecting ionic conductivity and battery internal resistance; it also determines the physicochemical properties of the solution (such as viscosity and water activity), thereby affecting gel behavior (such as curing time and mechanical strength). When the concentration is too low, the ionic conductivity of the electrolyte will decrease significantly, the battery internal resistance will increase, and the rate performance and power density will drop sharply. When the concentration is too high, it is not conducive to the synthesis and preparation of the electrolyte (high salt concentration may lead to salting-out effect, interfering with agar dissolution and gel network formation); at the same time, a longer curing time is required, and its relative mechanical strength is weak.

[0113] More preferably, the concentration of the non-alkaline zinc salt solution is 0.3 M. This concentration exhibits excellent ionic conductivity, along with good gelation properties and mechanical strength.

[0114] Preferably, in step S106, the injection time of the liquid precursor is 1 min to 2 min.

[0115] Optionally, the injection time is controlled within 1 to 2 minutes to complete the filling before the electrolyte precursor has significantly solidified, ensuring its sufficient flow and wetting of the electrode surface. If the injection time is too long, the precursor may gel prematurely in the injection port or narrow channels inside the soft package (such as the electrode edge), resulting in a sharp decrease in fluidity, incomplete filling, uneven coating, or leaving voids on the electrode surface.

[0116] Preferably, during the filling process in step S106, the liquid precursor with no obvious bubbles and relatively uniform composition from the lower layer of the defoaming stage in step S102 should be injected as much as possible. Although the entire precursor is still in a liquid state (95~99℃) at the end of the defoaming stage, the temperature of the uppermost liquid surface is the lowest due to heat radiation and convection dissipation, as it is in contact with room temperature air. For gelling agents such as agar, the gelation process is extremely sensitive to temperature. Even if the overall temperature is much higher than its freezing point, the surface layer may have approached or reached the critical state of gelation due to heat dissipation, forming a pre-gel layer or skin layer with inconsistent structural strength and significantly increased viscosity. If this layer is injected into the battery, the high-viscosity semi-solid material may clog the filling port; if heterogeneous gel fragments enter the battery, they will become defects during subsequent overall cooling and solidification, leading to stress concentration points or heterogeneous regions within the gel, affecting the uniformity of ionic conductivity; the semi-solid surface layer may encapsulate bubbles that have not escaped and carry them into the battery.

[0117] During the settling process, due to temperature differences and possible slight evaporation, the local concentration of the surface liquid may differ slightly from that of the bulk liquid. Absorbing the middle and lower layers of liquid effectively avoids this concentration gradient caused by mass and heat transfer, ensuring that the electrolyte precursor injected into each battery has a highly reproducible chemical composition and geler / zinc salt ratio. This is crucial for guaranteeing the performance consistency of mass-produced batteries.

[0118] During mixing and transfer, a very small amount of incompletely dispersed gel particles or trace amounts of dust from the environment may float on the liquid surface. Absorbing the lower and middle layers of liquid is equivalent to performing a simple purification, preventing these potential impurities from being introduced into the battery, thus ensuring the purity and electrochemical stability of the gel electrolyte.

[0119] It is understood that in step S106 of the present invention, the interface construction strategies of the liquid precursor for the zinc negative electrode and the air positive electrode are different, which is determined by the different working principles and structural characteristics of the two electrodes in the zinc-air battery.

[0120] For the zinc anode, which serves as the active material storage medium in the battery, an oxidation reaction (Zn→Zn) will occur during discharge. 2+ +2e -Zinc metal is gradually consumed. Therefore, to achieve high zinc utilization rate (ZUR) and uniform electrochemical reaction, it is essential to ensure a sufficient and continuous ion transport channel between the gel electrolyte and the active sites of the zinc anode. By completely coating the zinc anode with a liquid precursor possessing excellent fluidity and wettability, it is ensured that the precursor penetrates and fills the zinc foil surface. After in-situ gelation, this all-around coating structure is locked, forming a three-dimensional ion conduction network. This not only ensures efficient and uniform dissolution of zinc ions during discharge, effectively avoiding dendrite growth and corrosion problems caused by excessively high local ion concentrations or obstructed transport, but also provides continuous interfacial contact and mechanical support for the volume shrinkage and structural changes that may occur during the reaction consumption of the zinc anode, which is crucial for achieving high capacity and long cycle life.

[0121] The function of the air cathode is to catalyze the reaction of oxygen in the air. This electrode is typically composed of a porous catalyst layer with a high specific surface area. Its core characteristic is that it must maintain an open porous structure to ensure that the reactant oxygen can continuously and smoothly diffuse from the outside of the battery to the three-phase reaction interface inside the electrode. If a coating strategy similar to that used for zinc anodes is adopted, the gel electrolyte may excessively penetrate and block the pores of the air cathode, severely hindering oxygen transport and causing a sharp decline in battery performance. Therefore, the strategy of this invention is to enable the liquid precursor to form a close contact with the surface of the catalyst layer of the air cathode under the guidance of the interface buffer layer. This contact method can create a low-resistance, large-area ion conduction and charge transfer interface between the two, ensuring efficient electrochemical reaction while maximizing the preservation of the porosity of the air cathode and maintaining its permeability.

[0122] Preferably, in step S108, the cooling is natural cooling.

[0123] Alternatively, natural cooling (i.e., slow cooling at room temperature) is a low-stress curing method. It ensures that the temperature of the entire battery pack (including electrodes, packaging, and electrolyte precursor) decreases slowly and uniformly, avoiding internal stress or uneven shrinkage that may be caused by forced cooling, and contributing to the formation of a uniform, dense gel electrolyte structure. Natural cooling is simple and energy-efficient, reducing equipment complexity and production costs while ensuring battery performance.

[0124] The present invention will be further described in detail below with reference to specific embodiments, but these are exemplary and do not limit the scope of protection of the present invention in any way.

[0125] Example 1

[0126] like Figure 1 As shown, this embodiment provides a method for preparing an integrated non-alkaline gel zinc-air battery, specifically including the following steps:

[0127] Step S102, Preparation of electrolyte precursor: Add 0.5g of agar powder (gelling agent) to a beaker containing 10mL of 0.3M zinc trifluoromethanesulfonate (non-alkaline zinc salt solution). Then, place the beaker on a magnetic stirrer and heat and stir.

[0128] The heating and stirring process includes a mixing stage and a defoaming stage:

[0129] Mixing stage: Set the temperature to 120℃ and the speed to 800 rpm, and maintain stirring for 10 minutes under these conditions until the agar powder is completely dissolved and a uniform liquid precursor is formed.

[0130] Defoaming stage: After the mixing stage, the temperature and speed are gradually reduced in stages (110℃, 500 rpm), and finally the temperature is reduced to 99℃ and the speed is reduced to 300 rpm. Stirring is maintained under these conditions for 5 minutes to eliminate a large number of bubbles generated by high-temperature boiling during the mixing stage, so as to obtain a uniform, clear liquid precursor without obvious bubbles.

[0131] Step S104, Battery pre-packaging:

[0132] Negative electrode preparation: Cut zinc foil (zinc negative electrode) to the required size, and completely cover it with a conductive porous current collector layer (copper mesh in this embodiment). The copper mesh is led out as the negative electrode current collector.

[0133] Positive electrode preparation: The air positive electrode (mainly composed of nano-carbon powder) is rolled onto a titanium mesh (positive electrode current collector).

[0134] Buffer layer configuration: A glass fiber membrane (interface buffer layer) is covered on the carbon layer side of the air cathode to prevent the high-temperature precursor from directly impacting the carbon cathode and generating bubbles during subsequent filling.

[0135] Encapsulation: The negative electrode component and positive electrode component (including the interface buffer layer) prepared above are placed inside a transparent plastic encapsulation film (package). The positive and negative current collector outlets are located on the same side. The three sides of the package are heat-sealed, and a small opening is reserved at the bottom as a filling port.

[0136] Step S106, Liquid Precursor Injection: Using a pipette, draw up the liquid precursor prepared in step S102 at 99°C (preferably the middle and lower layer liquid) and slowly inject it into the packaging through the injection port reserved in step S104. The injection process should be completed within 1 to 2 minutes to ensure that the liquid precursor fully fills the gap between the positive and negative electrodes and completely wets and coats the zinc negative electrode.

[0137] Step S108, In-situ gelation: After filling, the filling port is immediately heat-sealed to seal the battery. The sealed battery pack is then placed in a room temperature environment to allow it to cool naturally. During the cooling process, the liquid precursor gels in-situ within the pack, forming a solid gel electrolyte, ultimately resulting in a non-alkaline gel zinc-air battery with an integrated, tightly contacted electrode-electrolyte structure.

[0138] Example 2

[0139] The preparation method of Example 2 is the same as that of Example 1, except that in step S102, the amount of agar used is 0.1g.

[0140] Example 3

[0141] The preparation method of Example 3 is the same as that of Example 1, except that in step S102, the amount of agar used is 0.7g.

[0142] Example 4

[0143] The preparation method of Example 4 is the same as that of Example 1, except that the concentration of zinc trifluoromethanesulfonate solution in step S102 is 0.1M.

[0144] Example 5

[0145] The preparation method of Example 5 is the same as that of Example 1, except that the concentration of zinc trifluoromethanesulfonate solution in step S102 is 0.2M.

[0146] Example 6

[0147] The preparation method of Example 6 is the same as that of Example 1, except that the concentration of the zinc trifluoromethanesulfonate solution in step S102 is 0.4M.

[0148] Example 7

[0149] The preparation method of Example 7 is the same as that of Example 1, except that the concentration of zinc trifluoromethanesulfonate solution in step S102 is 0.5M.

[0150] Comparative Example 1

[0151] The battery assembly method of Comparative Example 1 is the same as step S104 (battery pre-packaging) of Example 1, but without the interface buffer layer. In step S106, instead of using a gel electrolyte precursor, conventional 0.3M potassium hydroxide (KOH) liquid electrolyte is directly injected.

[0152] Comparative Example 2

[0153] The battery assembly method of Comparative Example 2 is the same as that of Comparative Example 1, except that the electrolyte used is a 0.3M liquid electrolyte (i.e. the zinc trifluoromethanesulfonate solution of Example 1, but without agar).

[0154] Comparative Example 3

[0155] The electrolyte preparation method of Comparative Example 3 is the same as step S102 (0.5g agar, 10mL zinc trifluoromethanesulfonate solution) in Example 1, except that the prepared liquid precursor is poured into a petri dish and allowed to cool naturally at room temperature to pre-solidify into a gel film. Then, the gel film is cut and placed between the zinc negative electrode (with copper mesh) and the air positive electrode (with buffer layer) in a physical stacking manner (i.e., the stacking method in the prior art), and then encapsulated.

[0156] Test case

[0157] To verify the performance of the embodiments of the present invention, the electrolytes or batteries prepared in Examples 1-8 and Comparative Examples 1-5 were subjected to performance tests.

[0158] 1. Ionic conductivity test:

[0159] For gel electrolytes: ohmic resistance (R) was measured at room temperature using an electrochemical workstation via electrochemical impedance spectroscopy (EIS). Ionic conductivity (σ) was calculated using the formula σ = L / (R × S), where L is the electrolyte thickness and S is the test area.

[0160] For liquid electrolytes: their ionic conductivity is measured directly at room temperature using a conductivity meter.

[0161] 2. Mechanical strength and setting time test:

[0162] Solidification time: The time required for the liquid precursor to completely lose its fluidity and form a self-supporting gel state is recorded by combining gelation timing observation with mechanical property testing.

[0163] Mechanical strength: The gel electrolyte to be tested is prepared into a standard geometric shape (such as a cylinder or cube). The sample is placed on the horizontal base of a texture analyzer or universal testing machine. A flat indenter is used to apply a vertically downward compressive force to the sample at a constant speed. The pressure applied to the sample (unit: kPa) and the deformation state of the sample are monitored and recorded in real time. When the pressure continues to increase, the gel sample is considered to have ruptured when macroscopically visible cracks, breakage, or irreversible structural collapse first appear. The pressure value corresponding to this point is the critical strength of the gel electrolyte against compressive structural integrity. The maximum pressure value tested in this invention is 86 kPa.

[0164] 3. Electrochemical performance testing:

[0165] Zinc || Zinc Symmetric Cell Life: Assembling CR2032 coin cells using a zinc sheet as the counter electrode. Life was measured at a current density of 1.0 mA·cm⁻¹. -2 The capacity is 1.0 mAh·cm -2 Under these conditions, constant current charge-discharge cycle tests were conducted, and the time for the battery to operate stably was recorded.

[0166] Zinc utilization rate (ZUR): The soft-pack batteries (effective area of ​​4cm×5cm) prepared in the test examples and comparative examples were tested by constant current discharge, the actual discharge capacity of the batteries was recorded, and the zinc utilization rate (ZUR) was calculated based on the theoretical capacity of the zinc negative electrode.

[0167] Full battery cycle life: The pouch cell is tested at 0.1 mA·cm⁻¹. -2 Long-cycle charge-discharge tests were conducted at a current density to record battery capacity retention and cycle time.

[0168] Performance Test Results and Analysis

[0169] According to the methods described in the test examples above, Examples 1 to 8 and Comparative Examples 1 to 5 were tested, and the resulting performance data are summarized in Table 1.

[0170] Table 1

[0171]

[0172] Based on the experimental data in Table 1, compared with Comparative Example 1 (a traditional alkaline liquid electrolyte), Example 1 exhibits a longer cycle life and significantly improved zinc utilization, directly demonstrating the fundamental advantages of non-alkaline systems in addressing carbonation failure and inhibiting zinc anode corrosion. Compared with Comparative Example 2 (a non-alkaline liquid electrolyte without gel), Example 1 demonstrates a longer cycle life and higher zinc utilization, indicating that chemical system modifications alone are insufficient to achieve a long cycle life; the integrated gel structure of this invention is crucial for maintaining interfacial stability and structural integrity. Compared with Comparative Example 3 (using a physical stacking method), Example 1 shows superior ionic conductivity and cycle life, strongly demonstrating the irreplaceable nature of liquid infusion and in-situ gelation processes in constructing low-impedance, tight interfaces.

[0173] Within the examples, by adjusting the amount of gelling agent and the concentration of zinc salt, the various performance indicators showed a regular change, demonstrating the controllability of the process of the present invention. Comparing Examples 1, 2, and 3 with different amounts of gelling agent, it can be found that with increasing amount, the mechanical strength of the gel significantly improves and the solidification time is greatly shortened; however, excessively high gelling agent amounts lead to a slight decrease in ionic conductivity and zinc utilization. Comparing Examples 1, 4, 5, 6, and 7 with different zinc salt concentrations, it can be seen that ionic conductivity gradually increases with increasing concentration, while mechanical strength decreases significantly after the concentration exceeds 0.4 M, and high concentrations also lead to excessively long solidification times. In summary, the formulation used in Example 1 is the optimal solution for achieving the best balance between high ionic conductivity, excellent mechanical strength, suitable curing time, and excellent electrochemical performance, enabling it to maintain high zinc utilization while achieving a long full-cell cycle life.

[0174] In summary, the technical solution of this invention fundamentally solves several technical bottlenecks of traditional zinc-air batteries through the synergy of a non-alkaline chemical system and an integrated in-situ gelation process.

[0175] To further demonstrate the technical effectiveness of the present invention, the following analysis will be conducted in conjunction with specific experimental test results and images.

[0176] Figure 2 The results show the ionic conductivity of Zn(OTf)₂ solutions at different concentrations. The results indicate that the ionic conductivity gradually increases with increasing concentration.

[0177] Figure 3 Optical photographs of AG electrolytes prepared from Zn(OTf)₂ solutions of different concentrations. The image visually demonstrates that the gel electrolytes prepared using the method of this invention are homogeneous, transparent, and solid, verifying that agar can be successfully gelled in Zn(OTf)₂ solutions of different concentrations.

[0178] Figure 4 The mechanical strength test results of the AG electrolyte of this invention are shown. The figure shows that when the concentration of Zn(OTf)2 solution is 0.4M or higher, its mechanical strength is significantly affected and shows a downward trend. This indicates that excessively high salt concentration may interfere with the formation of the agar three-dimensional network structure.

[0179] Figure 5 This diagram illustrates the mechanical strength and solidification time of the AG electrolyte corresponding to different concentrations of Zn(OTf)2 solutions according to the present invention. The diagram shows that the formulation selection of the present invention (Example 1) is based on the synergistic optimization of high ionic conductivity (ensuring low internal resistance of the battery), excellent mechanical strength (ensuring stable battery structure), and suitable curing time (ensuring process feasibility), achieving comprehensive performance optimization.

[0180] Figure 6 The graph shows the ionic conductivity and electrochemical window test results of the AG electrolyte prepared in Example 1. Figure 6 In the left graph, the horizontal axis Z' represents the real impedance in the electrochemical impedance spectroscopy (EIS) test, that is, the part of the impedance that is in phase with the current, and the vertical axis Z'' represents the imaginary impedance in the EIS test, that is, the part of the impedance that is 90 degrees out of phase with the current. By analyzing this impedance spectrum, the ionic conductivity of the electrolyte can be calculated, and the charge transfer kinetics at its electrode interface can be evaluated. Figure 6 The left figure shows that the gel electrolyte of Example 1 has an ionic conductivity as high as 21.0 mS·cm. -1 This value is much higher than that of many traditional gel electrolytes and is close to the level of liquid electrolytes, which is the basis for achieving high performance. Figure 6 The right figure shows that the electrochemical window of the gel electrolyte is widened compared to that of the liquid electrolyte, indicating that the gel electrolyte system has excellent electrochemical stability.

[0181] Figure 7 The graph shows the results of the water absorption tests on AG polymer and AG electrolyte. The results show that pure AG polymer (agar powder) can absorb nearly 20 times its own weight in water. The prepared AG electrolyte (Example 1) can also store more than 5 times its own weight in electrolyte. This demonstrates that the three-dimensional network structure of the gel has a strong liquid-locking ability, ensuring ion conduction and interfacial wetting during the cycling process.

[0182] Figure 8 This is a SEM microstructure image of the AG electrolyte. The image clearly shows that the gel electrolyte exhibits a highly cross-linked, porous three-dimensional network structure. This structure explains... Figure 7 Its high water absorption (liquid-locking) capacity, along with its abundant micron-sized pores and channels forming a continuous ion transport path, helps to store large amounts of electrolyte and provides a low-resistance pathway for the rapid migration of zinc ions. This is why it combines high mechanical strength (solid network) and high ionic conductivity (liquid channel).

[0183] Figure 9This diagram illustrates the interfacial reactions of the AG electrolyte with the air positive electrode and the zinc negative electrode, respectively. In traditional stacked structures, the pre-fabricated solid electrolyte and electrodes are in physical contact, resulting in significant gaps and air bubbles, leading to high interfacial impedance and impaired ion transport. However, in the integrated structure of this invention, the liquid precursor fully wets and coats the electrode surface during infusion. After cooling and gelation, a gapless, tight contact interface is formed between the gel electrolyte and the zinc negative electrode and the air positive electrode. This integrated structure significantly increases the effective three-phase reaction interface area, ensuring the continuity and efficiency of the ion transport path, thereby fundamentally reducing interfacial impedance and significantly improving the uniformity and stability of the interfacial reaction.

[0184] Figure 10 This is an optical image showing the interface between the AG electrolyte and the zinc anode. The image clearly shows that the gel electrolyte formed by the in-situ gelation process of this invention achieves a seamless, bubble-free, and tight bond with the zinc anode. This macroscopic morphology directly confirms... Figure 9 The superiority of the integrated interface structure described visually confirms the excellent wettability and encapsulation ability of the liquid precursor, as well as the stable, low-resistance contact interface formed after cooling and solidification.

[0185] Figure 11 This is the XRD pattern of the air cathode in the AG electrolyte system after charging and discharging. XRD (X-ray diffraction) is a common analytical technique used to determine the crystal structure and phase of materials. During testing, an X-ray beam is incident on the sample surface at a specific angle (θ). The regular arrangement of atoms within the crystal causes the X-rays to diffract. The diffraction conditions follow Bragg's law, and the diffraction angle is equal to the detection angle, both being θ. Therefore, the instrument actually scans and records twice the diffraction angle, i.e., 2θ. The horizontal axis "2θ" in the XRD pattern represents the range of angles swept by the instrument detector relative to the direction of the incident X-rays, i.e., twice the diffraction angle.

[0186] XRD results showed that the product of the discharge process was ZnO2, while the ZnO2 peak disappeared after charging. This confirms from the perspective of phase analysis that in the non-alkaline gel electrolyte of this invention, the battery system follows a reversible reaction pathway with ZnO2 as the discharge product. Figure 12 1mA·cm -2 The reaction mechanism of the air cathode at different charge-discharge depths under different current densities is shown in the figure. As shown, the cathode reaction exhibits highly consistent behavior under all conditions: the discharge process is stably maintained at a 1V plateau, and the voltage curve shows no significant decay, hysteresis, or deformation. This directly confirms from an electrochemical behavior perspective that the above reaction pathway has excellent reversibility and stability, and is consistent with... Figure 11 The results correspond to this.

[0187] Figure 11 and Figure 12This demonstrates that the integrated non-alkaline gel electrolyte system constructed in this invention drives a stable and reversible 2-electron Zn / ZnO2 reaction. This mechanism differs from the complex and poorly reversible oxygen reduction / evolution reaction (ORR / OER) in traditional alkaline systems. This highly reversible reaction pathway is one of the keys to the high cycle stability of the battery of this invention.

[0188] Figure 13 The XRD patterns are of zinc anodes immersed in liquid electrolyte (Comparative Example 2) and AG electrolyte (Example 1) for 15 days. The horizontal axis "2θ" in the XRD pattern represents the range of angles swept by the instrument detector relative to the direction of incident X-rays, which is twice the diffraction angle.

[0189] Figure 14 SEM and optical images of the zinc anode immersed in liquid electrolyte (Comparative Example 2) and AG electrolyte (Example 1) for 15 days are shown. The optical images and SEM images reveal that in the liquid electrolyte, the surface morphology of the zinc sheet is severely damaged and corroded; XRD patterns further confirm the formation of a large amount of zinc basic salts (byproducts) on its surface. However, in the AG electrolyte (Example 1), the zinc sheet surface retains its metallic luster and smooth morphology after 15 days of immersion, and no obvious byproducts are detected by XRD. This result demonstrates that the hydroxyl (-OH) groups abundant on the surface agar molecular chain are tightly bound to water molecules in the electrolyte through strong hydrogen bonds, greatly limiting the amount and activity of water. The effective reduction of water activity effectively inhibits hydrogen evolution corrosion (HER) and the accumulation of basic salt byproducts on the zinc anode.

[0190] Figure 15 The graph shows a comparison of the long-term cycling performance of the zinc-zinc symmetric battery in liquid electrolyte (Comparative Example 2) and AG electrolyte (Example 1). In the liquid electrolyte (Comparative Example 2), due to high water activity, severe side reactions, and uncontrollable dendrite growth, the symmetric battery quickly experienced short-circuit failure (<150h). However, the symmetric battery using the AG electrolyte (Example 1), thanks to the effective confinement of water activity and suppression of zinc dendrites by the gel, achieved a long-term stable cycling time of up to 850 hours. This demonstrates the significant advantage of the gel electrolyte of this invention in improving the stability of the zinc anode interface.

[0191] Figure 16 The image shows a confocal microscope image of the zinc anode in a zinc-zinc symmetric battery after 100 hours of cycling in a liquid electrolyte (Comparative Example 2). The image reveals extremely uneven distribution of fluorescence signal intensity and location, exhibiting numerous bright clusters and dark grooves. This indicates that the zinc deposition / dissolution process is highly localized and uncontrollable, leading to severely corroded electrode surfaces and intense dendrite growth, which is the direct cause of the short cycle life (<150 hours) in Comparative Example 2.

[0192] Figure 17 The image shows a confocal microscope image of the zinc anode of the zinc-zinc symmetric battery after 100 hours of cycling in an AG electrolyte (Example 1). The image reveals highly uniform fluorescence signal intensity and distribution, exhibiting a smooth and uniform surface morphology. This demonstrates that the zinc ion flux distribution is uniform in the gel electrolyte system of this invention, achieving dendrite-free and highly reversible zinc deposition / dissolution behavior. This uniform interfacial reaction is the microscopic basis for the ultra-long cycle life (850 hours) of the zinc-zinc symmetric battery, and also explains the high zinc utilization rate and high cycling stability of the entire cell.

[0193] Figure 18 The diagram shows the discharge performance and zinc utilization rate (ZUR) of the integrated pouch cell prepared in Example 1 of this invention. The results show that the pouch cell of Example 1 maintains stable capacity output under different discharge states, and the zinc utilization rate (ZUR) consistently remains above 80%, a value higher than most traditional zinc-based full battery systems. The gel electrolyte and structural design of this invention contribute to this excellent performance, especially the conductive porous current collector layer (i.e., the copper mesh in Example 1). This copper mesh, acting as a conductive framework, provides a robust electron conduction network during volume changes at the zinc anode. Even when the zinc active material (zinc foil) shrinks or breaks due to discharge consumption, a continuous electron conduction pathway is maintained, thus achieving extremely high ZUR.

[0194] Figure 19 The integrated pouch cell prepared for Example 1 was tested at 0.1 mA·cm⁻¹. -2 The graph shows the long-cycle performance at current density. The results show that the integrated pouch battery can cycle stably for more than 250 hours. Analysis of the aforementioned graphs reveals that the integrated non-alkaline gel battery of this invention successfully achieves a balance between high ZUR and long cycle life through the synergistic effects of the chemical system (non-alkaline), materials (hydrogel), process (in-situ infusion), and structure (copper mesh framework), demonstrating extremely high practical application value.

[0195] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An integrated non-alkaline gel zinc-air battery, characterized in that, The device includes a zinc negative electrode, an air positive electrode, a gel electrolyte, and a packaging body. The zinc negative electrode, the air positive electrode, and the gel electrolyte are all disposed within the packaging body, and the zinc negative electrode and the air positive electrode form an integral, tightly contacted structure with the gel electrolyte on both sides. The gel electrolyte is formed by in-situ gelation of a liquid precursor within the packaging body, the liquid precursor comprising a non-alkaline zinc salt solution and a gelling agent dissolved therein; The gelling agent includes at least one of agar, gelatin, carrageenan, gellan gum, and konjac glucomannan; An interface buffer layer is provided between the air positive electrode and the gel electrolyte; when the liquid precursor is poured into the package, the interface buffer layer is used to prevent the liquid precursor from directly contacting the air positive electrode and generating air bubbles, and after wetting, it adheres tightly to the air positive electrode to improve interface contact.

2. The integrated non-alkaline gel zinc-air battery according to claim 1, characterized in that, The non-alkaline zinc salt includes at least one of zinc trifluoromethanesulfonate, zinc chloride, zinc sulfate, zinc acetate, or zinc perchlorate.

3. The integrated non-alkaline gel zinc-air battery according to claim 1, characterized in that, The interface buffer layer includes at least one of glass fiber, polyacrylonitrile, non-woven fabric, and filter paper.

4. The integrated non-alkaline gel zinc-air battery according to claim 1, characterized in that, The zinc anode is wrapped with a conductive porous current collector layer. The conductive porous current collector layer is made of a conductive material that does not participate in the electrochemical reaction. The conductive porous current collector layer is used to maintain a continuous electron conduction path when the zinc active material layer shrinks in volume or breaks in structure due to the consumption of the reaction. The conductive porous current collector layer is a metal mesh, which is at least one of copper mesh, titanium mesh, or stainless steel mesh.

5. The integrated non-alkaline gel zinc-air battery according to claim 1, characterized in that, The current collector for the positive air electrode is made of titanium mesh, nickel mesh, copper mesh, or stainless steel mesh. And / or, The packaging body has ventilation holes in the area corresponding to the positive air electrode.

6. A method for preparing an integrated non-alkaline gel zinc-air battery as described in any one of claims 1 to 5, characterized in that, Includes the following steps: Step S102: Mix the gelling agent with the non-alkaline zinc salt solution and heat and stir to form a homogeneous liquid precursor; Step S104: Place the zinc negative electrode and the air positive electrode into the packaging body and partially seal them, leaving a filling port; Step S106: Inject the liquid precursor prepared in step S102 into the packaging body through the filling port, so that it covers the zinc negative electrode and is in close contact with the air positive electrode. Step S108: Seal the filling port and allow the liquid precursor to cool and gel in situ within the packaging to form an integrated non-alkaline gel zinc-air battery.

7. The preparation method according to claim 6, characterized in that, The heating and stirring in step S102 includes a mixing stage: stirring at a temperature of 115°C to 120°C at a speed of 600 rpm to 800 rpm for 10 to 15 minutes to completely dissolve the gelling agent in the non-alkaline zinc salt solution to form a liquid precursor; Following the mixing stage, a defoaming stage is also included: the liquid precursor is cooled and the rotation speed is reduced in stages until it is stirred at a temperature of 95°C to 99°C for 5 to 10 minutes at a rotation speed of 200 to 300 rpm to eliminate air bubbles.

8. The preparation method according to claim 6, characterized in that, In step S102, the mass ratio of the gelling agent to the volume of the non-alkaline zinc salt solution is (0.1g~0.7g):10mL; And / or, the concentration of the non-alkaline zinc salt solution is 0.1M to 0.5M.

9. The preparation method according to claim 6, characterized in that, In step S106, the injection time of the liquid precursor is 1 min to 2 min; And / or, in step S108, the cooling is natural cooling.

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