A negative electrode of a zinc-air battery and a preparation method and application thereof

Abstract

This invention discloses a negative electrode for a zinc-air battery, its preparation method, and its application. The negative electrode of the zinc-air battery includes a current collector and a negative electrode coating disposed on the surface of the current collector; the negative electrode coating includes a zinc-based material, a binder, and liquid metal. The negative electrode of the zinc-air battery proposed in this invention can effectively alleviate the uneven deposition of zinc in the negative electrode of the zinc-air battery, thereby effectively avoiding the formation of zinc dendrites, and can also effectively avoid the formation of a zinc oxide passivation layer (which lacks electrochemical activity) and the occurrence of hydrogen evolution side reactions. This invention also provides a method for preparing the above-mentioned negative electrode and its application.

Description

Technical Field

[0001] This invention relates to the field of secondary battery materials technology, and in particular to a negative electrode for a zinc-air battery, its preparation method, and its application. Background Technology

[0002] Oil and coal resources are finite and non-renewable. Wind and tidal energy are renewable resources, but their controllability is poor, and energy storage equipment is needed for their industrial utilization. To alleviate the large-scale consumption of non-renewable resources, various rechargeable batteries have been commercially developed for energy storage of renewable resources. Among them, lithium-ion batteries are relatively stable and technologically mature. However, lithium-ion batteries suffer from limited raw material resources (such as lithium and transition metals), poor safety, high cost, and limited energy density. Therefore, there is an urgent need to develop new rechargeable batteries to meet the requirements of high energy density, high efficiency, and low cost.

[0003] Zinc-air batteries use zinc-based materials as the negative electrode and oxygen reduction and evolution bifunctional catalysts to catalyze oxygen from the air as the positive electrode. The theoretical energy density of zinc-air batteries reaches 1086 Wh / kg, far exceeding that of lithium-ion batteries. Moreover, zinc resources are abundant and relatively inexpensive, making zinc-air batteries a promising candidate for electrochemical energy storage. However, traditional zinc-air battery negative electrodes suffer from problems such as zinc dendrites, zinc oxide passivation layers, hydrogen evolution side reactions, and uneven deposition, leading to short circuits and short lifespans. In particular, deep discharge generates a zinc oxide passivation layer, increasing the charge / discharge polarization potential and reducing energy efficiency. To address these issues, high-energy-density zinc negative electrodes utilize zinc paste or zinc oxide powder. By modifying the negative electrode to suppress these problems, zinc-air batteries with long cycle life and high energy density can be effectively obtained. However, existing zinc-air battery negative electrodes still easily develop problems such as zinc dendrites, hydrogen evolution reactions, and zinc oxide passivation layers. Summary of the Invention

[0004] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a negative electrode for a zinc-air battery that can effectively alleviate the uneven deposition of zinc in the negative electrode of the zinc-air battery, thereby effectively avoiding the formation of zinc dendrites, and can also effectively avoid the formation of a zinc oxide passivation layer (which has no electrochemical activity) and the occurrence of hydrogen evolution side reactions.

[0005] The present invention also provides a method for preparing the above-mentioned negative electrode.

[0006] The present invention also provides a zinc-air battery comprising the above-described negative electrode.

[0007] The present invention also provides a method for preparing the above-mentioned zinc-air battery.

[0008] The present invention also provides applications of the above-mentioned negative electrode or zinc-air battery.

[0009] According to an embodiment of a first aspect of the present invention, a negative electrode of a zinc-air battery is provided, the negative electrode comprising a current collector and a negative electrode coating disposed on the surface of the current collector;

[0010] The negative electrode coating includes zinc-based materials, binders, and liquid metal.

[0011] The negative electrode according to embodiments of the present invention has at least the following beneficial effects:

[0012] During the charging process of a zinc-air battery, zinc ions in the electrolyte and oxidized zinc in the negative electrode are reduced to elemental zinc. During the discharging process, the elemental zinc in the negative electrode is oxidized to zinc ions, or zinc oxide is formed and adheres to the surface of the negative electrode. The uneven deposition of elemental zinc and the uneven reduction of zinc oxide during this process lead to the formation of zinc dendrites. These zinc dendrites can puncture the separator, causing safety issues and reducing the service life of the zinc-air battery. Furthermore, hydrogen evolution reaction occurs at the negative electrode of the zinc-air battery. Compared to other rechargeable batteries using zinc-based negative electrodes, the zinc-air battery exhibits a higher charging potential, resulting in more severe zinc dendrite formation and hydrogen evolution reaction at the negative electrode.

[0013] The negative electrode provided by this invention includes a liquid metal (a metal that is liquid at room temperature). This metal can penetrate into the interior of the negative electrode, forming a flowing protective layer. The liquid state of the protective layer makes its distribution more uniform. During discharge, the conductivity of the liquid metal stabilizes the electric field distribution of the negative electrode, causing the zinc metal to oxidize uniformly to form fluffy zinc oxide (which is electrochemically active). Simultaneously, the liquid metal enters the interior of the zinc oxide (filling the voids), forming a stable conductive network. During charging, the conductive network formed by the liquid metal uniformly distributes the electric field of the negative electrode, and the liquid metal in the voids acts as a nucleation site for the reduction of zinc oxide, ultimately inducing the uniform reduction of zinc oxide / zinc ions to zinc metal. Thus, the presence of the liquid metal effectively avoids the formation of a zinc oxide passivation layer and zinc dendrites. Furthermore, the negative electrode provided by this invention includes a negative electrode coating, in which the liquid metal exists inside the negative electrode rather than on the surface. Therefore, it can suppress the formation of zinc dendrite seeds from within the negative electrode, thereby more effectively inhibiting the formation and growth of zinc dendrites and effectively reducing the overpotential during the charging and discharging process of the zinc-air battery.

[0014] Furthermore, since liquid metal can induce uniform deposition of zinc, it is equivalent to autonomously repairing the cracks generated on the negative electrode after long-term cycling of zinc-air batteries, thereby significantly improving the cycle life of the obtained zinc-air batteries.

[0015] During the zinc redox process at the negative electrode, the flowing liquid metal can self-fill the gaps formed during the discharge process, preventing zinc-based material particles from detaching. This avoids the influence of zinc-based material particles on the electrolyte, further extending the lifespan of the resulting zinc-air battery.

[0016] The low hydrogen evolution potential of liquid metals can suppress hydrogen evolution and improve energy efficiency.

[0017] The negative electrode provided by the present invention includes a binder, which can trap the liquid metal inside the negative electrode, thus avoiding safety issues such as short circuits caused by the transfer of liquid metal.

[0018] Furthermore, the zinc-based material in the negative electrode provides the zinc source, and the current collector is a conductor. The various components of this negative electrode work synergistically to improve the rate performance of the resulting zinc-air battery, achieving a cycle life of no less than 1000 hours. According to some embodiments of the present invention, the zinc-based material includes at least one selected from elemental zinc, zinc oxide, zinc hydroxide, zinc sulfide, zinc sulfite, zinc carbonate, zinc chloride, zinc acetate, zinc sulfate, zinc iodide, zinc bromide, zinc perchlorate, zinc citrate, zinc nitrate, zinc oxalate, zinc fluoride, zinc stannate, and zinc borate.

[0019] According to some embodiments of the present invention, the zinc-based material includes at least one of elemental zinc (Zn), zinc oxide (ZnO), zinc hydroxide (ZnOH), zinc carbonate (ZnCO3), zinc sulfite (ZnSO3), zinc fluoride (ZnF2), and zinc stannate (ZnSnO3).

[0020] According to some embodiments of the present invention, the zinc-based material is a mixture of elemental zinc and zinc oxide. Specifically, the ratio of elemental zinc to zinc oxide is 0.05 to 2:1; for example, it can be 1:10 to 11 or 1.5 to 2:1; more specifically, it can be about 5:3 or 7:73.

[0021] According to some embodiments of the present invention, the zinc-based material is a mixture of elemental zinc, zinc hydroxide, and zinc sulfite.

[0022] The mass ratio of elemental zinc to zinc hydroxide is 4 to 6:1, for example, it can be about 5:1.

[0023] The mass ratio of elemental zinc to zinc sulfite is 3 to 4:1, for example, approximately 5:1.5.

[0024] According to some embodiments of the present invention, the zinc-based material is a mixture of elemental zinc, zinc carbonate, zinc stannate, and zinc fluoride.

[0025] The mass ratio of elemental zinc to zinc carbonate is 1:7 to 9; for example, it can be approximately 1:8.

[0026] The mass ratio of elemental zinc to zinc stannate is 1:0.5 to 0.7; for example, it can be approximately 5:3.

[0027] The mass ratio of elemental zinc to zinc fluoride is 1:0.3 to 0.5; for example, it can be approximately 5:2.

[0028] According to some embodiments of the present invention, the adhesive comprises at least one selected from olefin polymers, polysiloxanes, cellulose derivatives, enol polymers, acrylic resins, epoxy resins, polyesters, polyurethanes, and perfluorosulfonic acid resins (Nafion).

[0029] The olefin polymers include at least one of polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), polyethylene (PE), polystyrene (EPS), and polyvinyl chloride (PVC).

[0030] Polysiloxanes include polydimethylsiloxane (PDMS);

[0031] Cellulose derivatives include sodium carboxymethyl cellulose (CMC-Na);

[0032] Enol polymers include polyvinyl alcohol (PVA).

[0033] According to some embodiments of the present invention, the adhesive includes at least one selected from polytetrafluoroethylene, polyvinyl alcohol, perfluorosulfonic acid resin, sodium carboxymethyl cellulose, styrene-butadiene rubber, polyvinylidene fluoride, polyvinyl chloride, and polyethylene.

[0034] According to some embodiments of the present invention, the adhesive is polytetrafluoroethylene.

[0035] According to some embodiments of the present invention, the adhesive is a mixture of polyvinyl alcohol and perfluorosulfonic acid resin.

[0036] The mass ratio of polyvinyl alcohol to perfluorosulfonic acid resin is 1:1 to 2, for example, it can be about 2:3.

[0037] According to some embodiments of the present invention, the adhesive is a mixture of sodium carboxymethyl cellulose and styrene-butadiene rubber.

[0038] The mass ratio of sodium carboxymethyl cellulose to styrene-butadiene rubber is 3 to 5:1, for example, approximately 4:1.

[0039] According to some embodiments of the present invention, the adhesive is a mixture of polyvinylidene fluoride, polyvinyl chloride and polyethylene.

[0040] The mass ratio of polyvinylidene fluoride to polyvinyl chloride is 2 to 3:1, for example, it can be about 5:2.

[0041] The mass ratio of polyvinylidene fluoride to polyethylene is 1.5 to 2:1, for example, it can be about 5:3.

[0042] According to some embodiments of the present invention, the melting point of the liquid metal is -40°C to 35°C. This ensures that the liquid metal remains liquid in the normal operating environment of the zinc-air battery, thereby better serving its functions such as uniformizing the conductive network in the negative electrode and filling gaps.

[0043] According to some embodiments of the present invention, at least one of the liquid metal mercury-based material and gallium-based material.

[0044] According to some embodiments of the present invention, the liquid metal includes at least one of mercury, mercury-gallium alloy, mercury-gallium-zinc alloy, gallium-indium alloy, gallium-indium-tin alloy, gallium-indium-zinc alloy, gallium-indium-tin-zinc alloy, and mercury-gallium-indium-tin alloy.

[0045] According to some embodiments of the present invention, the liquid metal includes at least one of mercury, mercury-gallium alloy, gallium-indium alloy, gallium-indium-tin alloy, gallium-indium-zinc alloy, and mercury-gallium-indium-tin alloy.

[0046] According to some embodiments of the present invention, the liquid metal is a gallium indium tin alloy. The melting point of the gallium indium tin alloy is approximately 10°C.

[0047] According to some embodiments of the present invention, the liquid metal is a mixture of mercury-gallium alloy and gallium-indium alloy.

[0048] The mass ratio of mercury-gallium alloy to gallium-indium alloy is 3 to 5:1, for example, it can be about 4:1.

[0049] The melting point of mercury-gallium alloy is approximately 29.5℃, and the melting point of gallium-indium alloy is approximately 12℃.

[0050] According to some embodiments of the present invention, the liquid metal is a mixture of gallium indium tin alloy and gallium indium zinc alloy.

[0051] The mass ratio of gallium indium tin alloy to gallium indium zinc alloy is 1:1.5 to 2.5, for example, it can be about 1:2.

[0052] The melting point of gallium indium zinc alloy is approximately 11°C.

[0053] According to some embodiments of the present invention, the liquid metal is a mixture of mercury, gallium indium tin alloy and mercury gallium indium tin alloy.

[0054] The mass ratio of mercury to gallium indium tin alloy is 1:0.8 to 1.2, for example, it can be about 1:1.

[0055] The mass ratio of mercury to mercury gallium indium tin alloy is 1:10 to 12, for example, it can be about 3:34.

[0056] Mercury has a melting point of approximately -38.9°C, while mercury gallium indium tin alloy has a melting point of approximately -40°C.

[0057] According to some embodiments of the present invention, the mass percentage of the liquid metal in the negative electrode coating is 1-50%.

[0058] According to some embodiments of the present invention, the mass percentage of the liquid metal in the negative electrode coating is 10-40%; specifically, it can be about 15%.

[0059] According to some embodiments of the present invention, the zinc-based material in the negative electrode coating has a mass percentage of 10% to 95%. Specifically, it may be about 50%, 75%, or 80%.

[0060] According to some embodiments of the present invention, the mass percentage of the binder in the negative electrode coating is 3% to 30%. Specifically, it can be about 5%, 10%, or 15%.

[0061] According to some embodiments of the present invention, the loading of the negative electrode coating on the current collector is 2–200 mg / cm³. -2 For example, it could be approximately 50 mg / cm³. -2 Or 120mg / cm -2 .

[0062] According to some embodiments of the present invention, the current collector includes at least one of a metal sheet, a metal foil, and a metal mesh.

[0063] According to some embodiments of the present invention, the material of the current collector includes at least one selected from steel, nickel, titanium, copper, tungsten, and molybdenum.

[0064] According to some embodiments of the present invention, the current collector includes at least one of tin mesh, copper mesh, titanium sheet and nickel foam.

[0065] According to an embodiment of a second aspect of the present invention, a method for preparing the negative electrode of the zinc-air battery is provided, the method comprising coating a mixture of the zinc-based material, a binder and liquid metal onto the current collector.

[0066] Since the preparation method adopts all the technical solutions of the negative electrode in the above embodiments, it has at least all the beneficial effects brought about by the technical solutions in the above embodiments.

[0067] Furthermore, the preparation method provided by this invention is simple, efficient, and low-cost, which is conducive to its industrialization.

[0068] According to some embodiments of the present invention, the mixing method of the mixture includes at least one of wet mixing and dry mixing.

[0069] The wet mixing process involves mixing the components with the addition of a solvent.

[0070] The solvent includes at least one of water, isopropanol, ethanol, acetone, and N-methylpyrrolidone.

[0071] For example, the solvent may specifically be a mixture of water and isopropanol in a 1:1 mass ratio;

[0072] For example, the solvent may specifically be a mixture of water, ethanol and acetone in a mass ratio of 8:1:1;

[0073] For example, the solvent can be a mixture of N-methylpyrrolidone and N-methylpyrrolidone in a mass ratio of 3:2.

[0074] The mass of the solvent is 1.5 to 2.5 times the sum of the masses of the zinc-based material, liquid metal, and binder, for example, it can be twice the mass.

[0075] According to some embodiments of the present invention, the mixing method includes at least one of grinding, stirring and sonication.

[0076] According to some embodiments of the present invention, the mixing time is 30 min to 12 h, specifically 1 h or 2.5 h.

[0077] According to some embodiments of the present invention, the mixing method is wet ball milling for 20 to 40 minutes, specifically wet ball milling for about 30 minutes.

[0078] According to some embodiments of the present invention, the mixing method is wet stirring for 50 min to 12 h, specifically wet stirring for about 60 min or wet stirring for 12 h.

[0079] According to some embodiments of the present invention, the mixing method includes sequential ultrasonication and wet stirring; wherein the ultrasonication time is 1.5 to 2.5 hours; and the stirring time is 25 to 35 minutes; for example, the mixing method includes sequential ultrasonication for 2 hours and wet stirring for 30 minutes.

[0080] In actual industrial production, the mixing method and duration can be adjusted according to the available production conditions, as long as the components are fully mixed.

[0081] According to an embodiment of a third aspect of the present invention, a zinc-air battery is provided, the zinc-air battery comprising the aforementioned negative electrode, air electrode, electrolyte and separator.

[0082] Since the zinc-air battery adopts all the technical solutions of the negative electrode in the above embodiments, it has at least all the beneficial effects brought about by the technical solutions in the above embodiments.

[0083] According to some embodiments of the present invention, the air electrode includes a support and a catalyst supported on the support.

[0084] According to some embodiments of the present invention, the catalyst comprises at least one selected from iron tetroxide, manganese dioxide, single-atom cobalt, cobalt oxide, and nickel sulfide.

[0085] According to some embodiments of the present invention, the catalyst is a mixture of cobalt oxide and nickel sulfide, wherein the mass ratio of cobalt oxide to nickel sulfide is 1:0.8 to 1.2; for example, it may be about 1:1.

[0086] According to some embodiments of the present invention, the raw materials for preparing the air electrode also include conductive agents and binders.

[0087] The conductive agent includes at least one of carbon black, acetylene black, and graphene.

[0088] The binder in the air electrode and the binder in the negative electrode can be the same or different; for example, they can be polytetrafluoroethylene.

[0089] According to some embodiments of the present invention, the mass ratio of the catalyst to the conductive agent is 8:0.8 to 1.2; for example, it can be about 8:1.

[0090] According to some embodiments of the present invention, the carrier includes at least one of a stainless steel mesh and a gas diffusion layer.

[0091] According to some embodiments of the present invention, the air electrode comprises a catalyst layer, a stainless steel mesh, and a gas diffusion layer stacked sequentially. The gas diffusion layer prevents leakage of the zinc-air battery electrolyte while allowing oxygen from the air to contact the catalyst. The stainless steel mesh acts as a current collector for the air electrode and has electrical conductivity.

[0092] According to some embodiments of the present invention, the gas diffusion layer comprises a polytetrafluoroethylene (PTFE) film and carbon supported on the PTFE film. The carbon includes activated carbon. The PTFE film has a porous structure. The porous structure serves to conduct gas while isolating liquid.

[0093] According to some embodiments of the present invention, the electrolyte is an aqueous solution.

[0094] According to some embodiments of the present invention, the solute of the electrolyte includes an alkali metal hydroxide.

[0095] The alkali metal hydroxide includes at least one of sodium hydroxide and potassium hydroxide.

[0096] The concentration of the alkali metal hydroxide is 4 to 10 mol / L, specifically about 6 mol / L or 9 mol / L.

[0097] According to some embodiments of the present invention, the solute of the electrolyte further includes a zinc compound.

[0098] The zinc compound includes at least one of zinc citrate, zinc oxide, and zinc acetate.

[0099] In the electrolyte, the concentration of the zinc compound is from 0 to saturation concentration, specifically, it may be saturated zinc oxide, 0.2 mol / L zinc acetate, or 0.2 mol / L zinc citrate.

[0100] According to some embodiments of the present invention, the zinc-air battery operates at 50 mA cm⁻¹ -2 Cycle life at current density ≥1200h.

[0101] According to some embodiments of the present invention, the zinc-air battery operates at 10 mA cm⁻¹ -2 Cycle life at current density ≥1500h.

[0102] According to some embodiments of the present invention, the zinc-air battery operates at 25 mA cm⁻¹ -2 Cycle life at current density ≥1350h.

[0103] According to some embodiments of the present invention, the zinc-air battery operates at 5 mA cm⁻¹ -2 Cycle life at current density ≥2000h.

[0104] According to some embodiments of the present invention, the zinc-air battery is at 0.5 mA cm -2 The voltage drop at the current density ranges from 0.3 to 0.4 V, specifically approximately 0.32 V or 0.36 V.

[0105] According to some embodiments of the present invention, the zinc-air battery operates at 1.0 mA cm⁻¹ -2 The voltage difference at the current density ranges from 0.35 to 0.4V, specifically approximately 0.37V or 0.39V.

[0106] According to some embodiments of the present invention, the zinc-air battery operates at 2.0 mA cm⁻¹ -2 The voltage difference at the current density ranges from 0.4 to 0.5 V, specifically approximately 0.45 V or 0.47 V.

[0107] According to some embodiments of the present invention, the zinc-air battery operates at 5.0 mA cm⁻¹ -2 The voltage difference at the current density ranges from 0.5 to 0.55V, specifically approximately 0.53V or 0.54V.

[0108] According to some embodiments of the present invention, the zinc-air battery operates at 10.0 mA cm⁻¹ -2The voltage drop at the current density ranges from 0.55 to 0.65V, specifically approximately 0.59V or 0.64V.

[0109] According to some embodiments of the present invention, the zinc-air battery operates at 20.0 mA cm⁻¹ -2 The voltage drop at the current density ranges from 0.65 to 0.75 V, specifically approximately 0.685 V or 0.72 V.

[0110] According to some embodiments of the present invention, the zinc-air battery is at 50.0 mA cm -2 The voltage difference at the current density ranges from 0.85 to 0.95V, specifically approximately 0.86V or 0.93V.

[0111] According to some embodiments of the present invention, the zinc-air battery operates at 100.0 mA cm⁻¹ -2 The voltage drop at current density ranges from 1.0 to 1.2V, specifically approximately 1.02V or 1.18V.

[0112] The pressure difference is the difference between the discharge voltage and the charging voltage.

[0113] According to an embodiment of a fourth aspect of the present invention, a method for producing the zinc-air battery is provided, the method comprising preparing the negative electrode and the air electrode separately, and then assembling the negative electrode, the air electrode, the electrolyte and the separator into the zinc-air battery.

[0114] Since the production method adopts all the technical solutions of the zinc-air battery in the above embodiments, it has at least all the beneficial effects brought about by the technical solutions in the above embodiments.

[0115] According to some embodiments of the present invention, the method for preparing the air electrode includes mixing and drying the raw materials for preparing the air electrode, rolling them into sheets, and then rolling the resulting sheet material together with the stainless steel mesh and the gas diffusion layer. The mixing method includes stirring.

[0116] According to an embodiment of the fifth aspect of the present invention, an application of the negative electrode, or the zinc-air battery, is proposed in the fields of power, energy storage, and 3C (computers, communications, and consumer electronics).

[0117] Since the application adopts all the technical solutions of the negative electrode or zinc-air battery of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments.

[0118] Unless otherwise specified, the term "about" in this invention actually means that the error is allowed to be within ±2%, for example, about 100 is actually 100 ± 2% × 100.

[0119] Unless otherwise specified, "between" in this invention includes the number itself, for example, "between 2 and 3" includes the endpoint values ​​2 and 3.

[0120] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0121] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0122] Figure 1 This is the cycling curve of the zinc-air battery obtained in Example 5 of the present invention;

[0123] Figure 2 This is the rate curve of the zinc-air battery obtained in Example 5 of the present invention;

[0124] Figure 3 This is the cycling curve of the zinc-air battery obtained in Example 6 of the present invention;

[0125] Figure 4 This is the cycling curve of the zinc-air battery obtained in Example 7 of the present invention;

[0126] Figure 5 This is the cycling curve of the zinc-air battery obtained in Example 8 of the present invention;

[0127] Figure 6 This is the rate curve of the zinc-air battery obtained in Example 8 of the present invention;

[0128] Figure 7 This is the cycling curve of the zinc-air battery obtained in Comparative Example 3 of this invention;

[0129] Figure 8 This is the rate curve of the zinc-air battery obtained in Comparative Example 3 of this invention;

[0130] Figure 9 This is the cycling curve of the zinc-air battery obtained in Comparative Example 4 of this invention;

[0131] Figure 10 This is the rate curve of the zinc-air battery obtained in Comparative Example 4 of this invention.

[0132] Figure 11 This is a scanning electron microscope image of the negative electrode used in the zinc-air battery of Example 8 before cycling.

[0133] Figure 12 This is a scanning electron microscope image of the negative electrode of the zinc-air battery obtained in Example 8 after cycling.

[0134] Figure 13 This is a scanning electron microscope image of the negative electrode of the zinc-air battery obtained in Comparative Example 4 after cycling. Detailed Implementation

[0135] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0136] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0137] Example 1

[0138] This embodiment prepares a negative electrode for a zinc-air battery. The specific raw materials are shown in Table 1, and the specific steps are as follows:

[0139] The raw materials in Table 1 were ball-milled with water (solvent) for 30 minutes and then dried. The mass of the solvent water was twice the mass of the raw materials (zinc-based material, liquid metal and binder).

[0140] The negative electrode coating precursor is prepared into sheet-like shapes by grinding (by rolling, using the adhesive properties of a binder to form sheets), and finally coated onto the current collector tin mesh by roll pressing to form the negative electrode coating.

[0141] Example 2

[0142] This embodiment prepares a negative electrode for a zinc-air battery. The specific raw materials are shown in Table 1. The specific steps differ from those in Example 1 in that:

[0143] The solvent is a mixture of water and isopropanol in a 1:1 mass ratio.

[0144] The mixing method is not ball milling, but stirring for 60 minutes.

[0145] The current collector is made of copper mesh.

[0146] Example 3

[0147] This embodiment prepares a negative electrode for a zinc-air battery. The specific raw materials are shown in Table 1. The specific steps differ from those in Example 1 in that:

[0148] The solvent is a mixture of water, ethanol and acetone in a mass ratio of 8:1:1.

[0149] The mixing method is to first sonicate for 2 hours, then stir for 30 minutes;

[0150] The current collector is a titanium sheet.

[0151] Example 4

[0152] This embodiment prepares a negative electrode for a zinc-air battery. The specific raw materials are shown in Table 1. The specific steps differ from those in Example 1 in that:

[0153] The solvent is a mixture of water and N-methylpyrrolidone in a mass ratio of 3:2;

[0154] The mixing method is to stir for 12 hours;

[0155] The current collector is made of nickel foam.

[0156] Example 5

[0157] This embodiment prepares a zinc-air battery, and the specific steps are as follows:

[0158] The negative electrode prepared in Example 1 was selected;

[0159] Preparation of the air electrode: Cobalt tetroxide (Nanjing Xianfeng Nano, XF138) was selected as a bifunctional catalyst. Cobalt tetroxide, polytetrafluoroethylene, and acetylene black were mixed in an aqueous solution at a mass ratio of 8:1:1, stirred, dried, and then rolled into a film. The film was then rolled in sequence with a catalyst-containing sheet material, a stainless steel mesh, and a gas diffusion layer to obtain the catalyst-prepared air electrode. The catalyst loading was 5 mg / cm³. -2 The gas consists of a polytetrafluoroethylene (PTFE) membrane and activated carbon supported on the PTFE membrane.

[0160] Preparation of electrolyte: The electrolyte is an aqueous solution containing 6 mol / L KOH and 0.2 mol / L zinc acetate;

[0161] Assembly: Assemble the above-mentioned negative electrode, air electrode, electrolyte and separator into a zinc-air battery.

[0162] Example 6

[0163] This embodiment prepares a zinc-air battery, which differs from Embodiment 5 in that:

[0164] (1) The negative electrode in this embodiment is derived from embodiment 2;

[0165] (2) The catalyst in this embodiment is manganese dioxide (Aladdin, M118109);

[0166] (3) The electrolyte in this embodiment is 9 mol / L KOH.

[0167] Example 7

[0168] This embodiment prepares a zinc-air battery, which differs from Embodiment 5 in that:

[0169] (1) The negative electrode in this embodiment is derived from embodiment 3;

[0170] (2) The catalyst in this embodiment is single-atom cobalt (CoNC) (Shenzhen Nano Energy, CoNC-111162);

[0171] (3) The electrolyte in this embodiment contains 4 mol / L KOH and saturated zinc oxide.

[0172] Example 8

[0173] This embodiment prepares a zinc-air battery, which differs from Embodiment 5 in that:

[0174] (1) The negative electrode in this embodiment is derived from embodiment 4;

[0175] (2) The catalyst in this embodiment is a mixture of cobalt oxide (Aladdin, C431733) and nickel sulfide (Aladdin, N475047) in a 1:1 mass ratio;

[0176] (3) The electrolyte in this embodiment contains 10 mol / L KOH and 0.2 mol / L zinc citrate.

[0177] Comparative Example 1: A negative electrode for a zinc-air battery was prepared in this comparative example. The specific raw materials are shown in Table 1, and the specific steps are the same as in Example 1.

[0178] Comparative Example 2

[0179] This comparative example prepared a negative electrode for a zinc-air battery. The specific raw materials are shown in Table 1, and the specific steps are the same as in Example 4.

[0180] Table 1. Raw materials for preparing the negative electrode in Examples 1-4 and Comparative Examples 1-2.

[0181]

[0182]

[0183] In Table 1, the proportions are mass ratios, and the percentages are the mass percentages of the sum of the masses of zinc-based materials, binders, and liquid metals. The negative electrode loading is the weight of the negative electrode coating per unit area of ​​the negative electrode. Parentheses after "polymer" indicate the weight-average molecular weight, in ten thousand. Parentheses after "liquid metal" indicate the melting point, in °C. Parentheses after "zinc-based reagent" indicate the particle size, where mesh number indicates the number of sieves it can pass through, and the specific particle size refers to the D50 particle size.

[0184] Comparative Example 3

[0185] This comparative example prepared a zinc-air battery, which differs from Example 5 in that:

[0186] The negative electrode of this comparative example comes from comparative example 1.

[0187] Comparative Example 4

[0188] This comparative example prepared a zinc-air battery, which differs from Example 8 in that:

[0189] The negative electrode of this comparative example comes from comparative example 2.

[0190] Test case

[0191] This test case tested the performance of the zinc-air batteries obtained in Examples 5-8 and Comparative Examples 3-4, specifically performing cycle performance tests and rate performance tests.

[0192] The conditions and results of the cyclic performance test are shown in Table 2.

[0193] Table 2 Cycle performance test of zinc-air batteries

[0194]

[0195]

[0196] Table 2 shows that the zinc-air battery provided by this invention has a long cycle life. However, if the negative electrode does not contain liquid metal, the cycle life decreases significantly. This is because the lack of the self-healing effect of liquid metal causes the negative electrode to crack during long cycles, reducing cycle performance. Furthermore, the lack of the guiding effect of liquid metal on zinc deposition on the negative electrode leads to the growth of zinc dendrites, which eventually puncture the separator, causing a short circuit. Partial cycle results are shown below. Figure 1 , 3 As shown in ~5, 7 and 9.

[0197] The test conditions and some test results of the rate performance of the zinc-air batteries obtained in Examples 5, 8 and Comparative Examples 3 to 4 are shown in Table 3.

[0198] Table 3 Rate Performance Test of Zinc-Air Batteries

[0199]

[0200] In Table 3, at the same rate, the smaller the voltage difference between the discharge voltage and the charging voltage, the better the performance of the obtained zinc-air battery. According to the results in Table 3, the zinc-air battery provided by this invention significantly avoids the formation of a passivation layer due to the presence of liquid metal, ultimately significantly improving its rate performance. Specifically, under the same conditions (Example 5 and Comparative Example 3; Example 8 and Comparative Example 4), if liquid metal is lacking, when the current density is 0.5–20 mA cm⁻¹… -2 Within this range, the voltage difference increases by 0.02–0.08V, specifically 0.04V, 0.06V, 0.05V, or 0.055V; when the current density is ≥50mA cm⁻¹ -2 At this time, the voltage drop increase is ≥0.13V, specifically 0.14V, 0.15V, 0.17V, or even higher. This further illustrates that the negative electrode of the zinc-air battery provided by this invention exhibits a more significant performance improvement at high rates. The relevant rate test results are as follows... Figure 2 , 6 As shown in 8 and 10.

[0201] This test also examined the morphology of the negative electrode used in Example 8 (the product of Example 4), and the negative electrodes obtained after cycling the zinc-air batteries in Example 8 and Comparative Example 4. Specific results showed that, regardless of whether the negative electrode contained liquid metal before cycling, they all exhibited similar surface morphologies, with residual rolling marks formed during the preparation process, and no obvious crystalline structure. The negative electrode of Example 8 after cycling had a smooth surface and a crystalline structure with rounded edges, indicating that zinc or zinc oxide was deposited during cycling without dendrite formation. In contrast, the negative electrode of the zinc-air battery obtained in Comparative Example 4 after cycling showed a rod-shaped, sharp structure, i.e., zinc dendrites capable of piercing the separator. This demonstrates that the negative electrode provided by this invention significantly improves the safety and service life of zinc-air batteries compared to conventional negative electrodes. Specific test results are as follows: Figures 11-13 As shown.

[0202] In summary, the negative electrode of the zinc-air battery provided by this invention has a self-repairing effect and guides uniform oxidation and reduction of the negative electrode due to the mutual cooperation between the components. Therefore, it significantly inhibits the formation of zinc dendrites, cracks and passivation layers on the surface of the negative electrode. Furthermore, the zinc-air battery including the negative electrode of this invention has excellent cycle life and rate performance, and is expected to have broad application prospects in the fields of energy storage, power and 3C.

[0203] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A negative electrode for a zinc-air battery, characterized in that, The negative electrode includes a current collector and a negative electrode coating disposed on the surface of the current collector; The negative electrode coating is composed of zinc-based materials, binders, and liquid metal; the mass percentage of the liquid metal in the negative electrode coating is 10-40%. The liquid metal includes at least one of mercury, mercury-gallium alloy, mercury-gallium-zinc alloy, gallium-indium alloy, gallium-indium-tin alloy, gallium-indium-zinc alloy, gallium-indium-tin-zinc alloy, and mercury-gallium-indium-tin alloy; The negative electrode is prepared by a method including the following steps: The mixture of the zinc-based material, binder, and liquid metal is applied to the current collector.

2. The negative electrode according to claim 1, characterized in that, The zinc-based material in the negative electrode coating has a mass percentage of 10-95%.

3. The negative electrode according to claim 1, characterized in that, The mass percentage of the binder in the negative electrode coating is 3-30%.

4. A method for preparing a negative electrode as described in any one of claims 1 to 3, characterized in that, The preparation method includes coating the current collector with a mixture of the zinc-based material, binder, and liquid metal.

5. A zinc-air battery, characterized in that, It includes the negative electrode, air electrode, electrolyte, and diaphragm as described in any one of claims 1 to 3.

6. The zinc-air battery according to claim 5, characterized in that, The air electrode includes a support and a catalyst supported on the support.

7. The zinc-air battery according to claim 6, characterized in that, The catalyst includes at least one of iron tetroxide, manganese dioxide, single-atom cobalt, cobalt oxide, and nickel sulfide.

8. A method for producing a zinc-air battery as described in any one of claims 5 to 7, characterized in that, The production method includes preparing the negative electrode and the air electrode separately, and then assembling the negative electrode, the air electrode, the electrolyte and the separator into the zinc-air battery.

9. An application of a negative electrode as described in any one of claims 1 to 3 or a zinc-air battery as described in any one of claims 5 to 7 in the power, energy storage, and 3C fields.

Images