Zinc-based batteries, their preparation methods, and electrical equipment

Abstract

The application discloses a zinc-based battery and a preparation method and an electric device thereof, the zinc-based battery comprising: a positive electrode sheet, a diaphragm and a negative electrode sheet; at least part of the surface of the positive electrode sheet and / or at least part of the surface of the diaphragm has a coating, and the coating comprises an amphoteric hydroxide. The zinc-based battery has strong cycle stability and good electrochemical performance.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to zinc-based batteries, their preparation methods, and electrical devices. Background Technology

[0002] As devices for converting electrical energy into chemical energy, batteries are widely used in daily life and work, and research on aqueous zinc-based batteries has gradually emerged in recent years. Zinc-based batteries use zinc as the negative electrode active material and have advantages such as low redox potential, high theoretical capacity, high safety, and high abundance of metal resources. They also have many advantages such as low cost, high energy density, safety and environmental friendliness, and wide availability of materials, which match current market demands and make them a research hotspot in academia and industry.

[0003] Currently, zinc-based batteries typically use water as the electrolyte solvent. During charging, hydrogen evolution reaction easily occurs, and the reduction of hydrogen ions induces the formation of byproducts such as basic zinc sulfate. These byproducts deposit simultaneously at both the positive and negative electrodes, easily leading to poor contact between the active material and the electrolyte at the positive electrode, and uneven deposition sites at the negative electrode. The latter will also disrupt the stability of subsequent deposition and gradually form dendrites, posing a risk of puncturing the separator and causing a short circuit, thus posing a challenge to the practical application of zinc-based batteries. Summary of the Invention

[0004] This application aims to at least partially solve one of the technical problems in the related art. Therefore, one objective of this application is to provide a zinc-based battery, its preparation method, and an electrical device thereof. The zinc-based battery of this application has strong electrolyte stability, is not prone to hydrogen evolution and byproduct formation, exhibits strong cycle stability, and has excellent electrochemical performance.

[0005] The first aspect of this application discloses a zinc-based battery. According to an embodiment of this application, the zinc-based battery includes: a positive electrode, a separator, and a negative electrode;

[0006] At least a portion of the surface of the positive electrode and / or at least a portion of the surface of the separator has a coating comprising an amphoteric hydroxide.

[0007] According to the zinc-based battery of the present application embodiments, at least a portion of the surface of the positive electrode and / or separator has a coating comprising an amphoteric hydroxide, which has a pH buffering effect, reducing the pH at the electrode interface. + or OH - The concentration can be effectively buffered during instantaneous changes, preventing hydrogen evolution and the formation of basic byproducts, thus reducing the possibility of battery runaway. Simultaneously, the amphoteric hydroxide has an inhibitory effect on water activity, thereby improving the stability of the electrolyte environment. Therefore, the overall cycle stability and electrochemical performance of zinc-based batteries are improved.

[0008] According to embodiments of this application, the zinc-based battery also has the following additional technical features:

[0009] According to embodiments of this application, the amphoteric hydroxide includes at least one hydroxide selected from boron, aluminum, silicon, zinc, gallium, germanium, arsenic, selenium, indium, tin, antimony, tellurium, lead, bismuth, manganese, polonium, and astatine.

[0010] According to embodiments of this application, the amphoteric hydroxide includes at least one of Al(OH)3, Be(OH)2, and Zn(OH)2.

[0011] According to embodiments of this application, the amphoteric hydroxide accounts for 66% to 100% of the mass of the coating.

[0012] According to embodiments of this application, the coating further comprises at least one of an adhesive and an interfacial adsorbent.

[0013] According to embodiments of this application, the adhesive includes at least one selected from polyvinylidene fluoride, polytetrafluoroethylene, carboxymethyl cellulose, styrene-butadiene rubber, styrene-acrylic acid, and polyacrylic acid;

[0014] And / or, the interfacial adsorbent includes anionic surfactants and / or nonionic surfactants.

[0015] According to embodiments of this application, the anionic surfactant includes at least one of alkyl sulfates, sulfonates, fatty acids, fatty acid ester sulfates, carboxylic acid soaps, and phosphate esters.

[0016] And / or, the nonionic surfactant includes at least one of polyoxyethylene alkylphenol ether and polyoxyethylene fatty alcohol ether.

[0017] According to an embodiment of this application, the coating includes:

[0018] 60 to 100 parts by weight of amphoteric hydroxide;

[0019] 0 parts by weight to 20 parts by weight of adhesive;

[0020] 0 to 10 parts by weight of interfacial adsorbent.

[0021] According to an embodiment of this application, the thickness of the coating is 60 μm to 250 μm.

[0022] According to an embodiment of this application, the zinc-based battery further includes an electrolyte, the electrolyte comprising water.

[0023] According to embodiments of this application, the positive electrode sheet includes a positive electrode active material, which includes at least one of manganese-based materials, vanadium-based materials, Prussian blue and its analogues, halogen-based materials, and organic materials.

[0024] A second aspect of this application discloses a method for preparing the zinc-based battery described in the first aspect. According to embodiments of this application, the method includes:

[0025] A coating slurry is applied to at least a portion of the surface of the positive electrode sheet and / or separator, and then dried to form the coating.

[0026] The coating slurry includes the amphoteric hydroxide.

[0027] According to embodiments of this application, the coating slurry further comprises at least one of a binder and an interfacial adsorbent, and a solvent.

[0028] According to embodiments of this application, the solvent includes at least one of N-methylpyrrolidone, N-dimethylamide, and deionized water.

[0029] According to embodiments of this application, the solid content of the coating slurry is 30% to 70% by mass.

[0030] A third aspect of this application discloses an electrical device. According to an embodiment of this application, the electrical device includes a zinc-based battery as described in the first aspect or a zinc-based battery obtained by the method for preparing the zinc-based battery as described in the second aspect.

[0031] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0032] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0033] Figure 1 This invention illustrates a pH cycle number measurement record diagram according to one embodiment of the present application;

[0034] Figure 2 This shows a forward linear voltammetric scan graph of one embodiment of this application;

[0035] Figure 3 The negative linear voltammetric scan curve of one embodiment of this application is shown. Detailed Implementation

[0036] The embodiments of this application are described in detail below. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0037] It should be noted that 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 technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, in the description of this application, unless otherwise stated, "multiple" means two or more.

[0038] The endpoints and any values ​​of the ranges disclosed in this application 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 in this application.

[0039] In this application, the terms "comprising" or "including" are open-ended expressions, meaning they include the content specified in this application but do not exclude other aspects.

[0040] Zinc-based batteries typically consist of a positive electrode, a negative electrode, an electrolyte, and a separator. The electrolyte usually uses water as a solvent and zinc salt as a solute, along with functional additives. Ions in the electrolyte exist in a solvated structure. During the reaction, upon reaching the electrode-electrolyte interface, they lose active free water and dissociate to release a certain amount of H+. + and OH - During battery charging, a trace amount of hydrogen evolution will occur due to the similar reaction voltage, posing a potential safety hazard to the battery. Simultaneously, during operation, the presence of the above-mentioned issues, along with H2O generated by intercalation and conversion reactions, will further contribute to the problem. + Consumption causes OH groups at the positive and negative electrode interfaces to be consumed. - Rapidly increasing concentrations can easily lead to the formation of poorly conductive basic zinc sulfate. Basic zinc sulfate has a loose morphology and cannot provide the necessary function and protection for the negative electrode like the SEI layer in lithium batteries, causing a decrease in discharge capacity during subsequent cycles and resulting in a reduction in energy density. These byproducts also cause uneven deposition sites at the negative electrode, easily disrupting the stability of subsequent depositions and gradually forming dendrites, posing a risk of puncturing the separator and causing short circuits, thus posing a challenge to the practical application of zinc-based batteries.

[0041] To address these issues, several solutions have been proposed. For example, modifying the electrolyte by introducing pH-buffered or water-activity-inhibiting additives. The former is ineffective at low concentrations due to slow mass transfer; however, at higher concentrations, these additives pose a challenge to the stability of the negative electrode. The latter often requires higher concentrations to be effective, which significantly increases costs and reduces electrolyte mass transfer efficiency. These strategies are limited to laboratory preparation and are difficult to implement in industrial production.

[0042] In view of this, this application coats the positive electrode sheet and / or separator surface of the zinc-based battery with a coating containing amphoteric hydroxides, which can effectively improve the stability of the electrolyte, reduce the occurrence of hydrogen evolution and by-product formation, and improve the cycle stability and electrochemical performance of the battery.

[0043] The first aspect of this application discloses a zinc-based battery. According to an embodiment of this application, the zinc-based battery includes: a positive electrode, a separator, and a negative electrode;

[0044] At least a portion of the surface of the positive electrode and / or at least a portion of the surface of the separator has a coating comprising an amphoteric hydroxide.

[0045] Amphoteric hydroxides can all react with H + OH - The reaction, in H + and OH - When the concentration changes, the ion concentration can be balanced through a reaction, thus having a pH buffering effect. Using amphoteric hydroxides as the coating material allows the H+ at the electrode interface to be neutralized. + or OH - The concentration is effectively buffered during instantaneous changes, preventing hydrogen evolution and the formation of basic byproducts, thus reducing the possibility of battery runaway. Simultaneously, the hydroxide inhibits water activity, thereby improving the stability of the electrolyte environment. Furthermore, compared to other types of amphoteric compounds, amphoteric hydroxides are more stable and less prone to dehydration. Moreover, amphoteric hydroxides possess not only ionic bonds but also hydrogen bonds, and the OH groups of amphoteric hydroxides... - The low electricity price of zinc weakens the interaction between cations and anions, resulting in a decrease in relative density and hardness, making it more suitable for zinc-based battery systems. Therefore, coatings containing amphoteric hydroxides can improve the overall cycle stability and electrochemical performance of zinc-based batteries.

[0046] It should be noted that the coating can be applied to the positive electrode, the separator, or both simultaneously. When the coating is applied to the positive electrode, the average discharge specific capacity is slightly higher than when it is applied to the separator. This is because the contact between the coating and the positive electrode is closer, shortening the electron or ion conduction path and thus improving electrochemical performance. When the coating is applied to the separator, it can radiate to the negative electrode interface to some extent, thus slightly improving stability.

[0047] According to embodiments of this application, the amphoteric hydroxide includes at least one hydroxide selected from boron, aluminum, silicon, zinc, gallium, germanium, arsenic, selenium, indium, tin, antimony, tellurium, lead, bismuth, manganese, polonium, and astatine. In some embodiments, the amphoteric hydroxide includes at least one selected from Al(OH)3, Be(OH)2, and Zn(OH)2. The aforementioned amphoteric hydroxide can effectively buffer the pH of the electrolyte, preventing hydrogen evolution and the formation of basic byproducts, while also inhibiting water activity and further improving the stability of the electrolyte environment. Therefore, it can better improve the cycle stability and electrochemical performance of zinc-based batteries.

[0048] According to embodiments of this application, the amphoteric hydroxide constitutes 66% to 100% of the coating by mass, for example, 66%, 70%, 75%, 80%, 85%, 90%, 95%, 99%, or 100%. The amphoteric hydroxide exhibits excellent adhesion and can be used as the sole component of the coating, adhering to at least a portion of the surface of the positive electrode and / or separator, without easily detaching. Alternatively, it can be used as a partial component of the coating. By satisfying the above conditions, the amphoteric hydroxide can more effectively buffer the pH of the electrolyte, preventing hydrogen evolution and the formation of basic byproducts. Simultaneously, it can suppress water activity, further enhancing the stability of the electrolyte environment. Therefore, it can better improve the cycle stability and electrochemical performance of zinc-based batteries.

[0049] According to embodiments of this application, the coating further comprises at least one of a binder and an interfacial adsorbent. The binder can enhance the adhesion between the coating and the positive electrode and / or the separator, ensuring uniform distribution and long-term stability of the coating, and also helps improve electronic conductivity, promoting electron exchange between the active material in the coating and the electrode, thereby improving the overall electrochemical performance and cycle stability of the battery.

[0050] Because amphoteric hydroxides are hydrophobic and have low affinity for aqueous electrolytes, they may cause poor contact between the coating and the electrolyte. This hinders the passage of substances (such as ions) from the electrolyte through the coating, thus limiting the mass transfer rate and slightly affecting the electrochemical performance of the battery. Interfacial adsorbents can improve the interaction between the coating and the electrolyte by increasing the hydrophilicity of the coating surface, thereby enhancing the mass transfer rate and battery performance, and contributing to improved battery stability and cycle life.

[0051] According to embodiments of this application, the binder comprises at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), styrene-acrylic acid (SA), and polyacrylic acid (PAA). This further enhances the adhesion between the coating and the positive electrode and / or separator, ensuring uniform coating distribution and long-term stability. It also helps to further improve electronic conductivity, promoting electron exchange between the active material in the coating and the electrode, thereby better improving the overall electrochemical performance and cycle stability of the battery.

[0052] According to embodiments of this application, the interfacial adsorbent comprises anionic surfactants and / or nonionic surfactants. This further increases the hydrophilicity of the coating surface, improves the interaction between the coating and the electrolyte, thereby enhancing mass transfer rate and battery performance, and contributing to improved battery stability and cycle life.

[0053] According to embodiments of this application, the anionic surfactant includes at least one selected from alkyl sulfates, sulfonates, fatty acids, fatty acid ester sulfates, carboxylic acid soaps, and phosphate esters; and / or, the nonionic surfactant includes at least one selected from polyoxyethylene alkylphenol ethers and polyoxyethylene fatty alcohol ethers. In some embodiments, the sulfonate may be sodium dodecylbenzenesulfonate (SDBS). This further increases the hydrophilicity of the coating surface, improves the interaction between the coating and the electrolyte, thereby better enhancing the mass transfer rate and battery performance, and contributing to improved battery stability and cycle life.

[0054] According to an embodiment of this application, the coating includes:

[0055] 60 parts by weight to 100 parts by weight of amphoteric hydroxide, for example, 60 parts by weight, 65 parts by weight, 70 parts by weight, 75 parts by weight, 80 parts by weight, 85 parts by weight, 90 parts by weight, 95 parts by weight, and 100 parts by weight;

[0056] The adhesive can be in the range of 0 parts by weight to 20 parts by weight, for example, 0 parts by weight, 1 part by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 10 parts by weight, 15 parts by weight, and 20 parts by weight.

[0057] Interfacial adsorbents in the range of 0 to 10 parts by weight, for example, 0 parts by weight, 1 part by weight, 2 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 8 parts by weight, and 10 parts by weight.

[0058] Amphoteric hydroxides, binders, and interfacial adsorbents, meeting the above conditions, can effectively buffer the pH value of the electrolyte, preventing hydrogen evolution and the formation of basic byproducts. Simultaneously, they can suppress water activity, further enhancing the stability of the electrolyte environment. Furthermore, the coating can stably adhere to the positive electrode and / or separator, is not easily detached, and exhibits good affinity with the electrolyte, facilitating electron and ion transport. Therefore, it better improves the overall electrochemical performance and cycle stability of the battery.

[0059] According to embodiments of this application, the thickness of the coating is 60 μm to 250 μm, for example, it can be 60 μm, 80 μm, 100 μm, 120 μm, 140 μm, 150 μm, 180 μm, 200 μm, 220 μm, 240 μm, or 250 μm. This effectively buffers the pH value of the electrolyte, preventing hydrogen evolution and the formation of basic byproducts, while also suppressing water activity and further improving the stability of the electrolyte environment. Moreover, it exhibits high electron and ion transport efficiency, low battery internal resistance, and is less prone to excessive volume expansion and contraction during charging and discharging, resulting in strong mechanical stability of the coating.

[0060] According to embodiments of this application, the zinc-based battery further includes: an electrolyte comprising water. The electrolyte also includes a solute comprising a zinc salt and a manganese salt. The zinc salt comprises one or more of ZnSO4, ZnCl2, Zn(NO3)2, Zn(H2PO4)2, ZnHPO4, Zn(CH3COO)2, Zn(ClO4)2, Zn(BF4)2, Zn(CF3SO3)2, and Zn(TFSI)2. The manganese salt comprises one or more of MnSO4, MnCl2, Mn(NO3)2, Mn(H2PO4)2, MnHPO4, Mn(CH3COO)2, Mn(ClO4)2, Mn(BF4)2, Mn(CF3SO3)2, and Mn(TFSI)2.

[0061] According to an embodiment of this application, the positive electrode sheet includes a positive active material, a binder, a conductive agent, and a current collector.

[0062] According to embodiments of this application, the positive electrode active material includes manganese-based, vanadium-based, Prussian blue and its analogues, organic materials, halogen-based materials, etc., wherein the positive electrode active material can be loaded onto the current collector by grinding and coating with a conductive agent and a binder.

[0063] According to embodiments of this application, the conductive agent includes at least one of conductive graphite, acetylene black, Super P, Ketjen black, carbon nanotubes, carbon fibers, metal fibers, graphene, etc., and the binder is selected from at least one of PVDF, HSV, PTFE, CMC, SBR, SA, PAA, etc.

[0064] According to embodiments of this application, the positive electrode conductive current collector includes carbon felt, carbon paper, carbon cloth, stainless steel mesh, titanium mesh, stainless steel foil, and titanium foil, etc.

[0065] According to the embodiments of this application, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet in a solvent to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0066] According to embodiments of this application, the negative electrode sheet includes a zinc metal plate, foil, and mesh, specifically including a negative electrode active material, a conductive agent, a binder, and a current collector.

[0067] According to embodiments of this application, the negative electrode active material comprises zinc powder with different particle sizes.

[0068] According to embodiments of this application, the selection of conductive agent and binder is consistent with that of the positive electrode.

[0069] According to embodiments of this application, the negative electrode conductive current collector includes metallic copper, metallic titanium, stainless steel, etc.

[0070] According to embodiments of this application, the membrane material includes at least one of the following: glass fiber, mixed cellulose ester, hydrophilic nylon, hydrophilic PVDF, and polypropylene, etc.

[0071] According to the embodiments of this application, the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet in a solvent to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0072] According to embodiments of this application, a zinc-based battery may include an outer packaging. This outer packaging is used to encapsulate the positive electrode, the negative electrode, and the electrolyte.

[0073] According to an embodiment of this application, the outer packaging may include a shell and a cover. The shell may include a bottom plate and side plates connected to the bottom plate, the bottom plate and side plates forming a receiving cavity. The shell has an opening communicating with the receiving cavity, and the cover can be placed over the opening to close the receiving cavity.

[0074] According to embodiments of this application, the outer packaging of a zinc-based battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell.

[0075] The outer packaging of zinc-based batteries can also be a pouch, such as a bag-type pouch. The material of the pouch can be plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0076] The zinc-based battery of this application may be in the form of a battery cell, a battery module, or a battery pack. In some embodiments, battery cells may be assembled into a battery module, and the number of battery cells contained in a battery module may be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery module. In some embodiments, battery modules may also be assembled into a battery pack, and the number of battery modules contained in a battery pack may be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0077] A second aspect of this application discloses a method for preparing the zinc-based battery described in the first aspect. According to embodiments of this application, the method includes: coating a coating slurry onto at least a portion of the surface of a positive electrode and / or a separator, and drying it to form the coating; wherein the coating slurry comprises the amphoteric hydroxide. The features and advantages described above for zinc-based batteries also apply to this method and will not be repeated here.

[0078] According to embodiments of this application, the coating slurry further comprises at least one of a binder and an interfacial adsorbent, and a solvent.

[0079] According to embodiments of this application, the solvent includes at least one of N-methylpyrrolidone, N-dimethylamide, and deionized water. This allows for the complete dissolution of the coating components, forming a uniform slurry and contributing to a uniform coating.

[0080] According to embodiments of this application, the solid content of the coating slurry is 30% to 70% by mass, for example, 30%, 40%, 50%, 60%, or 70% by mass. This effectively buffers the pH of the electrolyte, preventing hydrogen evolution and the formation of basic byproducts, while also suppressing water activity and further improving the stability of the electrolyte environment. Furthermore, the coating adheres stably to the positive electrode and / or separator, is not easily detached, and has good affinity with the electrolyte, which is beneficial for electron and ion transport. This further enhances the overall electrochemical performance and cycle stability of the battery.

[0081] A third aspect of this application discloses an electrical device. According to an embodiment of this application, the electrical device includes a zinc-based battery as described in the first aspect or a zinc-based battery obtained by the method for preparing the zinc-based battery as described in the second aspect.

[0082] Battery cells, battery modules, and battery packs can be used as power sources for electrical devices or as energy storage units for electrical devices. Electrical devices can include, but are not limited to, mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0083] As electrical equipment, battery cells, battery modules, or battery packs can be selected according to their usage requirements.

[0084] As one example, the electrical device can be a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements of the electrical device, a battery pack or battery module can be used.

[0085] Another example of a power device could be a mobile phone, tablet computer, laptop computer, etc. Such devices typically require a slim and lightweight design and can use individual battery cells as their power source.

[0086] The following will explain the solution of this application with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0087] Example 1

[0088] The components, related parameters, and assembly process of the battery described in this example are as follows:

[0089] Positive electrode sheet: β-MnO2 powder as the active material, KS6 powder as the conductive agent, and PVDF powder as the binder are weighed in a mass ratio of 100:30:10. NMP solvent is added until the solid content reaches 50%. The mixture is then stirred using a vacuum degassing machine for 3 minutes at a speed of 4000 rpm. A 0.1 μm thick stainless steel foil is used as the current collector, and the slurry is coated using a 250 μm doctor blade at a coating speed of 1 cm / s. The coated electrode sheet is then placed in a 90℃ oven and baked for 6 hours or more.

[0090] Coating: Al(OH)3 powder as the active material, PVDF powder as the binder, and sodium dodecylbenzenesulfonate (SDBS) as the interfacial adsorbent were weighed at a mass ratio of 100:10:2. NMP solvent was added until the solid content reached 40%. The mixture was then stirred using a vacuum degassing machine for 3 minutes at a speed of 4000 rpm. The baked electrode sheet was used as a substrate, and the slurry was coated using a 200 μm doctor blade at a coating speed of 1 cm / s. The coated electrode sheet was placed in a 90℃ oven and baked for 3 hours or more. The dried electrode sheet was then cut into circular electrode sheets with a diameter of 1.2 cm using a cutting machine.

[0091] Negative electrode: A commercial zinc sheet with a thickness of 0.1μm is used, which is cut into a circular electrode with a diameter of 1.3cm using a cutting machine.

[0092] Battery Assembly: The above-mentioned electrode sheets are used as positive and negative electrodes, respectively, with 2 mol / L MnSO4 + 1 mol / L ZnSO4 as the electrolyte. A CR2032 coin cell assembly is used for assembly, with a glass fiber separator. The order of assembly is: positive electrode shell, positive electrode sheet, separator, electrolyte, negative electrode sheet, gasket, spring contact, and negative electrode shell. The assembly is then performed using an automatic coin cell sealing machine. The electrolyte volume is 100 μL, and the diameter of the circular separator is 1.6 cm. The sealing machine is designed for a pressure of 650 kg and a sealing time of 2 seconds.

[0093] The differences between Examples 2-21, Comparative Examples 1-4 and Example 1 are shown in Table 1.

[0094] Cyclic performance test

[0095] To demonstrate the improvement in battery performance caused by the insoluble amphoteric hydroxide coating, the batteries prepared in Examples 1-21 and Comparative Examples 1-4 were subjected to electrochemical performance tests. The test methods are as follows:

[0096] Charge-discharge tests were conducted using the Wuhan Landian electrochemical test cabinet. The current parameter was set to 0.5C based on the active material mass, ensuring that the charging and discharging times were both 2 hours. The cutoff voltage during charging was 1.8V, and the cutoff voltage during discharging was 0.4V. The cycle count was set to 1000 cycles, with the actual cycle count determined based on performance. Points were taken at 20mV or 30s intervals, and the test cabinet voltage / current specifications needed to be higher than the actual voltage / set current. After the test, the actual discharge specific capacity during the cycle was calculated. The average discharge capacity of the first 50 cycles was used as the baseline (0%). Cycles with a specific capacity in the range of (0-30)% to (0+30)% were considered stable discharge cycles. The total number of cycles was the stable discharge cycle count. The test results are shown in Table 1.

[0097] Table 1

[0098]

[0099]

[0100] Since the definition of stable cycle count is related to the discharge specific capacity during the cycle, the length of the cycle count can reflect the stability of subsequent cycles. When the overall capacity decays significantly, the battery is considered to have failed.

[0101] As shown in Table 1, compared with Comparative Examples 1-3, the zinc-based batteries in Examples 1-21 using coatings containing amphoteric hydroxides all exhibited higher average discharge specific capacity and stable discharge cycles. This indicates that after introducing the amphoteric coating, the electrode-electrolyte interface is regulated by the coating material's control over the interfacial ion concentration, creating a more stable electrochemical reaction environment and thus improving overall cycle stability. Comparative Example 4, due to the use of tin sulfide in the amphoteric sulfide, has a weaker ability to regulate acidity and alkalinity, resulting in inferior electrochemical performance compared to amphoteric hydroxides.

[0102] The comparison between the data from Examples 1 and 2, 3 and 4, and 5 and 6 shows that the position of the coating has a certain impact on battery performance. Compared to when the coating is located on the separator, when the coating is located on the positive electrode, the contact between the coating and the positive electrode is closer, shortening the electron or ion conduction path and resulting in a higher average discharge specific capacity. When the coating is placed on the separator, it can radiate to the negative electrode interface to a certain extent, thus slightly improving stability.

[0103] As can be seen from the data in Examples 1-6, there are certain differences among different types of insoluble amphoteric hydroxides, which are related to the properties of the compounds themselves. For example, zinc hydroxide has better compatibility with zinc-based batteries, thus improving the number of stable cycles, while aluminum hydroxide and beryllium hydroxide have stronger ion control capabilities, resulting in higher average discharge specific capacity.

[0104] As can be seen from the data in Examples 1 and 14-16, the use of binders and interfacial adsorbents in the coating can also help improve the discharge specific capacity and stability. Among them, the binder mainly acts on the structural stability of the coating, thus having a significant impact on the cycle stability; the interfacial adsorbent, on the other hand, improves the system activation rate by promoting interfacial wetting efficiency, thus having a significant impact on the discharge specific capacity.

[0105] As can be seen from the data in Examples 1 and 17, when the proportion of amphoteric hydroxide in the coating is low, its contact with the electrolyte is weakened, and its ability to buffer pH and inhibit water activity is reduced, which will simultaneously affect the specific capacity and cycle stability.

[0106] As can be seen from the data in Examples 1 and 18, a higher proportion of interfacial adsorbent in the coating does not further improve the specific capacity or stability. Instead, it occupies the contact sites of the amphoteric hydroxide, resulting in a slight decrease in performance.

[0107] As can be seen from the data in Examples 1 and 19, the performance also decreased when the proportion of binder in the coating was too high. This is because binders are generally long-chain structures, and excessively high content is not conducive to dispersion, resulting in a decrease in the number of contact sites for the amphoteric hydroxide.

[0108] As can be seen from the data in Examples 1, 20 and 21, excessive coating thickness does not help improve performance, but instead increases cost and occupies more volume; excessive coating thickness reduces the total amount of amphoteric hydroxides, weakens the overall controllability, and reduces performance.

[0109] Example 22

[0110] The difference between Example 22 and Example 1 is that the battery assembly form is changed from a coin cell to a beaker battery. The specific assembly steps are as follows:

[0111] The battery was assembled using a beaker battery assembly, with platinum clips used to clamp the positive and negative electrodes, ensuring that the relative immersion area of ​​the positive and negative electrodes in the electrolyte was 1 cm². 2 .

[0112] Comparative Example 5

[0113] The difference between Comparative Example 5 and Example 22 is that it does not contain a coating.

[0114] Running pH measurement

[0115] To illustrate the stabilizing effect of insoluble amphoteric hydroxides on the pH environment of the electrolyte, pH measurements were performed on Example 22 and Comparative Example 5. The test methods and data analysis are as follows:

[0116] The pH values ​​of the electrolyte under initial conditions and after each discharge cycle were measured using a Shanghai Leici PHS-3E benchtop pH meter. Calibration was performed using a pH buffer solution before pH testing. Charge-discharge cycles were conducted using a Wuhan Landian electrochemical testing cabinet. Current parameters were set to 0.1C based on the active material mass, with a charging cutoff voltage of 1.8V and a discharging cutoff voltage of 0.4V. Test results are as follows: Figure 1 As shown.

[0117] Comparing the two curves, it can be seen that the pH value of Example 11 remained stable at around 4.3 from the initial stage to the subsequent stages, without significant fluctuations; while Comparative Example 5 not only experienced more drastic pH fluctuations in the early stage, but also reached a pH value of around 5 in the later stage, which was higher than that of Example 22. This indicates that the amphoteric hydroxide coating can achieve a more effective pH buffering effect, and the overall pH value is lower after use, making it more suitable for the current system.

[0118] Linear voltammetric scanning test

[0119] To verify the inhibitory effect of insoluble amphoteric hydroxides on water activity, Example 1 and Comparative Example 1 were subjected to linear voltammetry tests. The test methods and data analysis are as follows:

[0120] Linear voltammetric scanning was performed using an EC-lab electrochemical workstation. The open-circuit voltage was used as the starting potential, and 3.5V and -1V were used as ending potentials. A scan rate of 1mV / s was used for both positive and negative scans. The test results are as follows: Figure 2 , 3 As shown.

[0121] like Figure 2 , 3 As shown, in the oxygen evolution stage caused by the forward scan, the overall peak current of the side reaction peak in Example 1 is small, and there is no obvious current disturbance after gas production. Similarly, in the hydrogen evolution stage caused by the negative scan, the overpotential at the side reaction peak in Example 1 is larger, the peak current is smaller, and there is no test interruption caused by the current rapidly reaching the safe current value. In contrast, the smaller overpotential and larger peak current at the side reaction peak in Comparative Example 1 prove that it is more prone to the corresponding side reaction, and the violent current fluctuation in the later part of the scan further reflects that the stability of the system is lower than that of Example 1.

[0122] Since the magnitude of the current at the same potential is positively correlated with the reaction rate, and the larger the overpotential, the more difficult the reaction is, it can be concluded that Example 1, which uses amphoteric hydroxides, is less likely to have side reactions such as hydrogen evolution and oxygen evolution than Comparative Example 1. This means that the water activity is significantly suppressed, and a stable electrolyte environment is better maintained.

[0123] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A zinc-based battery, characterized in that, Comprising: a positive electrode sheet, a separator, and a negative electrode sheet; at least part of a surface of the positive electrode sheet and / or at least part of a surface of the separator has a coating layer, the coating layer comprises an amphoteric hydroxide, the amphoteric hydroxide comprises at least one of Al(OH)3, Be(OH)2, and Zn(OH)2, and the mass ratio of the amphoteric hydroxide in the coating layer is 66% to 100%.

2. The zinc-based battery of claim 1, wherein, The coating layer further comprises at least one of a binder and an interfacial adsorbent.

3. The zinc-based battery of claim 2, wherein, The binder comprises at least one of polyvinylidene fluoride, polytetrafluoroethylene, carboxymethyl cellulose, butadiene-styrene rubber, styrene-acrylic acid, and polyacrylic acid; And / or, the interfacial adsorbent comprises an anionic surfactant and / or a non-ionic surfactant.

4. The zinc-based battery of claim 3, wherein, The anionic surfactant comprises at least one of alkyl sulfate, sulfonate, fatty acid, fatty acid ester sulfate, carboxylic acid soap compound, and phosphate ester compound; And / or, the non-ionic surfactant comprises at least one of polyoxyethylene alkyl phenol ether and polyoxyethylene fatty alcohol ether.

5. The zinc-based battery of any one of claims 1-4, wherein, The coating layer comprises: 60 parts by weight to 100 parts by weight of the amphoteric hydroxide; 0 parts by weight to 20 parts by weight of the binder; 0 parts by weight to 10 parts by weight of the interfacial adsorbent.

6. The zinc-based battery of any one of claims 1-4, wherein, The thickness of the coating layer is 60 μm to 250 μm.

7. The zinc-based battery of claim 5, wherein, The thickness of the coating layer is 60 μm to 250 μm.

8. The zinc-based battery of any one of claims 1-4, wherein, The positive electrode sheet comprises a positive electrode active material, the positive electrode active material comprises at least one of manganese-based material, vanadium-based material, Prussian blue and its analogues, halogen-based material, and organic material; And / or, the zinc-based battery further comprises an electrolyte, the electrolyte comprises water.

9. The zinc-based battery of claim 5, wherein, The positive electrode sheet comprises a positive electrode active material, the positive electrode active material comprises at least one of manganese-based material, vanadium-based material, Prussian blue and its analogues, halogen-based material, and organic material; And / or, the zinc-based battery further comprises an electrolyte, the electrolyte comprises water.

10. The zinc-based battery of claim 6, wherein, The positive electrode sheet comprises a positive electrode active material, the positive electrode active material comprises at least one of manganese-based material, vanadium-based material, Prussian blue and its analogues, halogen-based material, and organic material; And / or, the zinc-based battery further comprises an electrolyte, the electrolyte comprises water.

11. A method of preparing a zinc-based battery according to any one of claims 1-10, characterized in that, Comprising: coating a coating slurry on at least part of a surface of a positive electrode sheet and / or a separator, drying to form a coating layer; The coating slurry comprises the amphoteric hydroxide.

12. The method of claim 11, wherein, The coating slurry further comprises at least one of a binder and an interfacial adsorbent and a solvent.

13. The method of claim 12, wherein, The solvent comprises at least one of N-methyl pyrrolidone, N-dimethyl amide, and deionized water.

14. The method according to any one of claims 11-13, characterized in that, The solid content of the coating slurry is 30% to 70% by mass.

15. An electrical device, characterized by The zinc-based battery obtained by the method for preparing the zinc-based battery according to any one of claims 11 to 14.

Images