Zinc negative electrode with hydrogen inhibition function and preparation method thereof

Abstract

The application discloses a zinc negative electrode with hydrogen inhibition function and a preparation method thereof. The zinc negative electrode comprises a current collector and an electrode material layer coated on at least one side surface of the current collector. The electrode material layer comprises a zinc-based active material, a conductive agent, a binder and a hydrogen inhibition functional component. The hydrogen inhibition functional component is at least one of oxides, sulfides and hydroxides of one or more metal elements selected from bismuth, selenium, tin, indium and lead. In the electrode material layer, the hydrogen inhibition functional component is non-uniformly distributed, and the content of the hydrogen inhibition functional component on the side close to the current collector is higher than that on the side far from the current collector. The zinc negative electrode can improve the interface hydrogen inhibition effect, improve the utilization rate of additives, effectively avoid the electrode structure failure caused by hydrogen bubbles, and improve the cycle stability and service life of the zinc negative electrode.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a zinc anode with hydrogen suppression function and its preparation method. Background Technology

[0002] Currently, the mainstream method for preparing zinc anodes in zinc-nickel batteries involves uniformly mixing zinc-based active materials, conductive agents, binders, and hydrogen-suppressing additives (such as bismuth oxide (Bi2O3) and indium hydroxide (In(OH)3)) to form a slurry, which is then directly coated onto the surface of the current collector. After drying and compaction, the electrode is formed. This process is widely used in industrial production due to its simplicity and strong compatibility, but it still has significant shortcomings in terms of hydrogen suppression performance and electrode stability.

[0003] Electrochemical hydrogen evolution reaction in the zinc anode of a zinc-nickel battery mainly concentrates in two regions: one is the current collector-electrode material interface, which becomes the preferential site for hydrogen evolution reaction due to electron enrichment effect. The essence of interfacial hydrogen evolution is the transfer of electrons from the current collector to H+ in the electrolyte. + The transfer is accelerated by the contact gap between the electrode material and the current collector; secondly, in local areas inside the electrode material, the uneven reaction of the active material and defects in the distribution of the conductive network lead to excessively high local current density, which triggers local hydrogen evolution.

[0004] In existing technologies, hydrogen-suppressing additives are uniformly mixed with zinc-based active materials, resulting in a mismatch between the strong regionality of the hydrogen evolution reaction and the uniform distribution of the additives. The hydrogen evolution suppression effect at the current collector-electrode material interface is limited, and the risk of gas generation cannot be avoided. Furthermore, excessively dispersed hydrogen-suppressing additives within the electrode material fail to fully exert their function, instead leading to a decrease in battery energy density and reduced hydrogen suppression efficiency.

[0005] In addition, the hydrogen gas generated at the interface between the current collector and the electrode material will form microbubbles. During the growth and escape of these bubbles, local stress will be generated, which will damage the interfacial bonding between the electrode material and the current collector, directly pushing off the electrode particles at the interface and causing structural failure problems such as interface peeling and coating detachment. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this application is to provide a zinc anode with hydrogen suppression function and its preparation method, which can solve the technical problem in existing technologies where hydrogen gas is easily generated at the current collector-electrode material interface, leading to the detachment of the electrode material.

[0007] To achieve one or more of the above objectives or other objectives, a first aspect of this application provides a zinc negative electrode with hydrogen suppression function, comprising a current collector and an electrode material layer coated on at least one side surface of the current collector; the electrode material layer comprises a zinc-based active material, a conductive agent, a binder, and a hydrogen suppression functional component, wherein the hydrogen suppression functional component is selected from at least one of the oxides, sulfides, and hydroxides corresponding to one or more metal elements selected from bismuth, selenium, tin, indium, lead, and cadmium;

[0008] In the electrode material layer, the hydrogen suppression functional component is non-uniformly distributed, and the content of the hydrogen suppression functional component on the side closer to the current collector is higher than the content on the side farther away from the current collector.

[0009] Furthermore, the zinc-based active material is one or more of zinc powder and zinc alloy powder; the conductive agent is selected from one or more of acetylene black, Super P, carbon nanotubes, graphene, conductive graphite, and metal powder; the binder is selected from one or more of polyvinyl alcohol, sodium carboxymethyl cellulose, polyvinylidene fluoride, and styrene-butadiene rubber; and the current collector is selected from one of nickel-plated steel strip and copper foil.

[0010] Furthermore, the hydrogen-suppressing functional component accounts for 40% to 60% of the mass on the side closer to the current collector, and 0% to 5% of the mass on the side farther from the current collector. The mass percentage of the hydrogen-suppressing functional component is distributed in a gradient from the side closer to the current collector to the side farther from the current collector.

[0011] Furthermore, the electrode material layer includes a first functional region close to the current collector and a second functional region away from the current collector. The mass percentage of the hydrogen inhibition functional component in the first functional region is 40% to 60%, and the mass percentage of the hydrogen inhibition functional component in the second functional region is 0% to 5%. The area between the first functional region and the second functional region is an intermediate region where the mass percentage of the hydrogen inhibition functional component is gradient.

[0012] Furthermore, the thickness of the first functional region is 10μm~25μm; the thickness of the second functional region is 100μm~250μm.

[0013] A second aspect of this application provides a method for preparing a zinc anode with hydrogen suppression function, used to prepare the aforementioned zinc anode with hydrogen suppression function, the preparation method comprising:

[0014] A first slurry and a second slurry are prepared, wherein the first slurry comprises a conductive agent, a binder, a hydrogen-suppressing functional component, a solvent, and an optional zinc-based active material, and the second slurry comprises a conductive agent, a binder, a zinc-based active material, a solvent, and an optional hydrogen-suppressing functional component; the content of the hydrogen-suppressing functional component in the first slurry is higher than the content of the hydrogen-suppressing functional component in the second slurry, and the mass percentage of the zinc-based active material in the first slurry is lower than the mass percentage of the zinc-based active material in the second slurry;

[0015] The first slurry is applied to at least one side of the current collector surface, and the applied first slurry is pre-dried to a semi-cured state;

[0016] The second slurry is coated onto the semi-cured first slurry layer, and the coated second slurry is pre-dried to a semi-cured state to obtain a pre-dried double-coated zinc anode.

[0017] The pre-dried double-coated zinc anode is fused by rolling with an elastic rubber roller under the first pressure to obtain a pre-pressed zinc anode.

[0018] Dry the pre-pressed zinc negative electrode;

[0019] The dried pre-pressed zinc anode is rolled with a rigid pressure roller at a second pressure greater than the first pressure to obtain the zinc anode with hydrogen suppression function.

[0020] Furthermore, the solvent is selected from organic solvents or water, and the solvent of the first slurry is of the same type as the solvent of the second slurry. The binder is selected from one or more of polyvinyl alcohol, sodium carboxymethyl cellulose, polyvinylidene fluoride, and styrene-butadiene rubber.

[0021] Furthermore, the zinc-based active material is one or more of zinc powder and zinc alloy powder.

[0022] Furthermore, the conductive agent is selected from one or more of acetylene black, Super P, carbon nanotubes, graphene, conductive graphite, and metal powder.

[0023] Furthermore, when preparing the first slurry, the hydrogen-suppressing functional component, conductive agent, binder, and zinc-based active material are added to the solvent in a mass ratio of (40~60):(10~20):(10~30):(0~30) and mixed to disperse evenly.

[0024] Furthermore, when preparing the second slurry, the hydrogen-suppressing functional component, conductive agent, binder, and zinc-based active material are added to the solvent in a mass ratio of (0~5):(5~120):(10~20):(65~85) and mixed to disperse evenly.

[0025] Furthermore, the process conditions for pre-drying the coated first slurry to a semi-cured state are: temperature 60℃~80℃, drying time 1min~5min.

[0026] Furthermore, the process conditions for pre-drying the coated second slurry to a semi-cured state are: temperature 60℃~80℃, drying time 3min~8min.

[0027] Furthermore, the process conditions for drying the pre-pressed zinc anode are: a temperature of 90℃~120℃ and a drying time of 10min~30min.

[0028] Further, the step of coating the second slurry onto the semi-cured first slurry layer and pre-drying the coated second slurry to a semi-cured state to obtain a pre-dried double-layer coated zinc anode includes:

[0029] The second slurry is coated onto the semi-cured first slurry layer;

[0030] Let it stand for 5 to 30 minutes in the range of 20℃ to 40℃;

[0031] The second slurry is pre-dried to a semi-cured state to obtain a pre-dried double-coated zinc anode.

[0032] The zinc anode with hydrogen suppression function and its preparation method provided in this application have a non-uniform distribution of hydrogen suppression functional components in the electrode material layer, with the content on the side closer to the current collector being higher than that on the side farther away from the current collector. This can improve the interface hydrogen suppression effect, increase the utilization rate of additives, effectively avoid electrode structure failure caused by hydrogen evolution bubbles, and improve the cycle stability and service life of the zinc anode. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] in:

[0035] Figure 1 This is a schematic diagram of the zinc negative electrode in one embodiment;

[0036] Figure 2 This is a schematic flowchart of the preparation process of the zinc negative electrode in one embodiment;

[0037] Figure 3 This is a comparison graph showing the cycle capacity retention and coulombic efficiency of the batteries in Example 1 and Comparative Example 1.

[0038] Figure 4 Photographs of the zinc electrode and separator of the battery in Example 1 after it has been disassembled and subjected to 200 cycles at room temperature;

[0039] Figure 5 The image shows the zinc electrode and separator of the battery in Comparative Example 1 after it has been disassembled and subjected to 200 cycles at room temperature. Detailed Implementation

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application, are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, not to describe a particular order.

[0041] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0042] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings.

[0043] Reference Figure 1 This application provides a zinc negative electrode with hydrogen suppression function, including a current collector 1 and an electrode material layer 2 coated on at least one side of the current collector; the electrode material layer 2 includes a zinc-based active material, a conductive agent, a binder and a hydrogen suppression functional component, wherein the hydrogen suppression functional component is selected from at least one of the oxides, sulfides and hydroxides of one or more metal elements selected from bismuth, selenium, tin, indium, lead and cadmium.

[0044] In the electrode material layer 2, the hydrogen suppression functional component is non-uniformly distributed, and the content of the hydrogen suppression functional component on the side closer to the current collector 1 is higher than the content on the side farther away from the current collector 1.

[0045] In this embodiment, the hydrogen-suppressing functional component is selected from at least one of the oxides, sulfides, and hydroxides corresponding to one or more metal elements selected from bismuth, selenium, tin, indium, lead, and cadmium. Exemplary examples include bismuth oxide (Bi₂O₃), bismuth hydroxide (Bi(OH)₃), bismuth trisulfide (Bi₂S₃), indium hydroxide (In(OH)₃), indium trioxide (In₂O₃), stannous oxide (SnO), tin dioxide (SnO₂), and tin hydroxide (Sn(OH)₄). These substances all possess high hydrogen evolution overpotentials, effectively suppressing the hydrogen evolution side reaction occurring at the zinc anode in the alkaline electrolyte. Furthermore, they are chemically stable and do not easily decompose under battery operating conditions.

[0046] The hydrogen-suppressing functional component is non-uniformly distributed in electrode material layer 2. Specifically, the content is higher on the side closer to current collector 1 and lower on the side farther away from current collector 1. That is, the content of the hydrogen-suppressing functional component gradually decreases from the bottom to the surface of electrode material layer 2. It should be noted that this gradual decrease does not refer to a linear uniform decrease, but rather to a general decreasing trend.

[0047] The current collector interface is a core high-risk area for hydrogen evolution side reactions in zinc-based batteries. In this application, a region with a high content of hydrogen-inhibiting components is first prepared on the current collector surface to achieve coverage and protection of the hydrogen evolution sites. Taking Bi₂O₃ as an example, the hydrogen-inhibiting functional component undergoes an in-situ reduction reaction during the first charge of the battery, with the reaction formula: Bi₂O₃ + 3Zn = 2Bi + 3ZnO. The in-situ generated metallic bismuth (Bi) has excellent high hydrogen evolution overpotential characteristics, which can significantly increase the hydrogen ion (H₂O) concentration. + The reaction energy barrier that allows the hydrogen to gain electrons and generate hydrogen (H2) is blocked, thus blocking the hydrogen evolution reaction at the source and reducing the hydrogen evolution rate.

[0048] Because the interface between current collector 1 and electrode material layer 2 has an electron enrichment effect, it is the core region where the hydrogen evolution reaction is most likely to occur and has the highest reaction intensity. Therefore, enriching a high content of hydrogen-suppressing functional components in this region can form a dense hydrogen-suppressing barrier, blocking the hydrogen evolution reaction at the interface from the source and preventing hydrogen bubbles from falling onto the electrode material at the interface and damaging the overall electrode structure. In the region far from current collector 1, the electron enrichment level is significantly reduced, and the driving force of the hydrogen evolution reaction is significantly weakened. Appropriately reducing the content of hydrogen-suppressing functional components can reduce the waste of hydrogen-suppressing components in this region and increase the proportion of zinc-based active materials, thereby improving the energy density of the zinc anode. Correspondingly, the content of zinc-based active materials increases from the side closer to current collector 1 (i.e., the bottom of electrode material layer 2) to the side farther from current collector 1 (the surface of electrode material layer 2). It should be noted that this increase in content does not refer to a linear and uniform increase, but rather to a general increasing trend.

[0049] The zinc anode of this application uses a non-uniformly distributed hydrogen-suppressing additive to enhance the interface hydrogen suppression effect, improve the additive utilization rate, effectively avoid electrode structure failure caused by hydrogen evolution bubbles, and at the same time improve the cycle stability and service life of the zinc anode.

[0050] In some embodiments, the zinc-based active material is one or more of zinc powder and zinc alloy powder.

[0051] In some embodiments, the conductive agent is selected from one or more of acetylene black, SuperP, carbon nanotubes, graphene, conductive graphite, and metal powder.

[0052] In some embodiments, the adhesive is selected from one or more of polyvinyl alcohol, sodium carboxymethyl cellulose, polyvinylidene fluoride, and styrene-butadiene rubber.

[0053] In some embodiments, the current collector is selected from nickel-plated steel strip and copper foil.

[0054] In some embodiments, the hydrogen-suppressing functional component accounts for 40% to 60% of the mass on the side near the current collector, and 0% to 5% of the mass on the side away from the current collector, with the mass percentage of the hydrogen-suppressing functional component exhibiting a gradient distribution from the side near the current collector to the side away from the current collector. The 40% to 60% mass percentage near the current collector is beneficial because the interface between the current collector and the electrode material layer is an area of ​​electron enrichment, a high-risk region for hydrogen evolution side reactions in zinc anodes. This content range can form a stable hydrogen-suppressing layer at the interface, effectively suppressing interface hydrogen evolution. Simultaneously, this content ensures sufficient amounts of conductive agent and binder, maintaining the electronic conductivity of the electrode interface and the bonding stability between the electrode material layer and the current collector, reducing problems such as conductivity obstruction and coating peeling. The 0% to 5% mass percentage of the hydrogen-suppressing functional component on the side away from the current collector reduces the probability and extent of hydrogen evolution side reactions, as this region is far from the electron-rich interface. A small amount of the hydrogen-suppressing functional component is sufficient to meet basic hydrogen suppression requirements, and a zero-content setting is also suitable for applications with low hydrogen evolution risk. The mass percentage of the hydrogen-suppressing functional component is distributed in a gradient along the thickness of the electrode, which can maintain a continuous transition in the component distribution inside the electrode material layer, avoid the formation of internal interfaces due to abrupt changes in component content, thereby ensuring uniform conduction of ions and electrons inside the electrode, reducing local current unevenness and side reactions, and improving the cycle stability and operational reliability of the zinc anode.

[0055] In some embodiments, the electrode material layer includes a first functional region close to the current collector and a second functional region away from the current collector. The mass percentage of the hydrogen inhibition functional component in the first functional region is 40% to 60%, and the mass percentage of the hydrogen inhibition functional component in the second functional region is 0% to 5%. The area between the first functional region and the second functional region is an intermediate region where the mass percentage of the hydrogen inhibition functional component is gradient.

[0056] The first functional area is in direct contact with the current collector. The mass percentage of the hydrogen inhibition functional component in this area is 40% to 60%, the mass percentage of the zinc-based active material is 0% to 30%, the mass percentage of the conductive agent is 10% to 20%, and the mass percentage of the binder is 10% to 30%. This ratio can take into account the interface hydrogen inhibition effect, electronic conduction and structural bonding strength.

[0057] The second functional area is the surface layer of the electrode material layer away from the current collector. In this area, the mass percentage of the hydrogen inhibition functional component is controlled at 0-5%, the mass percentage of the zinc-based active material is 65-85%, the mass percentage of the conductive agent is 5-10%, and the mass percentage of the binder is 10-20%.

[0058] The intermediate region between the first and second functional regions is a transitional connection region. Within this region, the mass percentage of the hydrogen-suppressing functional component exhibits a continuous gradient distribution, gradually transitioning from a high percentage near the first functional region to a low percentage near the second functional region. This prevents the formation of a delamination interface within the electrode material layer due to abrupt changes in component content. Simultaneously, the content of the zinc-based active material in the intermediate region transitions in a gradient in sync with the changes in the hydrogen-suppressing functional component, while the contents of the conductive agent and binder remain within a stable range.

[0059] In some embodiments, the thickness of the first functional region is 10 μm to 25 μm. For example, the thickness of the first functional region can be 10 μm, 15 μm, 20 μm, 25 μm, etc.; the thickness of the second functional region is 100 μm to 250 μm. For example, the thickness of the second functional region can be 100 μm, 150 μm, 200 μm, 250 μm, etc. The first functional region is an interface hydrogen suppression and bonding area closely attached to the current collector. The aforementioned thickness is sufficient to cover the surface of the current collector and form a continuous hydrogen suppression barrier. Simultaneously, the relatively thin thickness does not excessively occupy the overall electrode space, and its impact on the overall energy density of the battery is minimal. The second functional region is the main electrochemical reaction region of the zinc anode, undertaking the core functions of zinc dissolution and deposition. The aforementioned thickness can match the electrode structure design and usage requirements of conventional zinc-nickel batteries.

[0060] Reference Figure 2This application also provides a method for preparing a zinc anode with hydrogen suppression function, used to prepare the zinc anode with hydrogen suppression function of any of the foregoing embodiments. The preparation method includes:

[0061] S1: Prepare a first slurry and a second slurry, wherein the first slurry includes a conductive agent, a binder, a hydrogen-suppressing functional component, a solvent, and an optional zinc-based active material, and the second slurry includes a conductive agent, a binder, a zinc-based active material, a solvent, and an optional hydrogen-suppressing functional component; the content of the hydrogen-suppressing functional component in the first slurry is higher than the content of the hydrogen-suppressing functional component in the second slurry, and the mass percentage of the zinc-based active material in the first slurry is lower than the mass percentage of the zinc-based active material in the second slurry;

[0062] S2: Apply the first slurry to at least one side surface of the current collector, and pre-dry the applied first slurry to a semi-cured state;

[0063] S3: Coat the second slurry onto the semi-cured first slurry layer, and pre-dry the coated second slurry to a semi-cured state to obtain a pre-dried double-coated zinc anode;

[0064] S4: The pre-dried double-coated zinc anode is rolled and fused with an elastic rubber roller under the first pressure to obtain a pre-pressed zinc anode.

[0065] S5: Dry the pre-pressed zinc negative electrode;

[0066] S6: The dried pre-pressed zinc anode is rolled with a rigid pressure roller at a second pressure, which is greater than the first pressure, to obtain the zinc anode with hydrogen suppression function.

[0067] In this embodiment, in step S1 above, the first slurry is a bottom slurry close to the current collector, containing a conductive agent, binder, hydrogen-suppressing functional component, and solvent, and zinc-based active material can be selectively added according to actual needs; the second slurry is a surface slurry away from the current collector, containing a conductive agent, binder, zinc-based active material, and solvent, and hydrogen-suppressing functional component can be selectively added according to actual needs. According to the ratio requirements of electrode functional zones, the content of hydrogen-suppressing functional component in the first slurry is higher than that in the second slurry, and the mass percentage content of zinc-based active material in the first slurry is lower than that in the second slurry. Both slurries are thoroughly stirred and dispersed until they are uniform and free of agglomeration.

[0068] In some embodiments, the solvent is selected from organic solvents or water, and the solvent of the first slurry is the same as that of the second slurry. The binder is selected from one or more of polyvinyl alcohol, sodium carboxymethyl cellulose, polyvinylidene fluoride, and styrene-butadiene rubber. When water-based binders such as sodium carboxymethyl cellulose, styrene-butadiene rubber, and polyvinyl alcohol are used, deionized water is preferred as the solvent. When oil-soluble binders such as polyvinylidene fluoride are used, organic solvents such as N-methylpyrrolidone (NMP) can be used. Using the same solvent for the first and second slurries can avoid the problem of uneven interlayer interfacial tension caused by differences in solvent polarity. On the other hand, it helps the diffusion of interlayer components and the entanglement of binder molecular chains in the semi-dry state in subsequent steps. In some embodiments, a small amount of dispersant is added to the solvent to improve the dispersion effect. Exemplary dispersants may include sodium dodecylbenzene sulfonate (SDBS).

[0069] In some embodiments, the zinc-based active material is one or more of zinc powder and zinc alloy powder;

[0070] In some embodiments, the conductive agent is selected from one or more of acetylene black, Super P, carbon nanotubes, graphene, conductive graphite, and metal powder. In the first slurry, to avoid an increase in interfacial impedance due to a high content of hydrogen-suppressing components, the conductive agent may be carbon nanotubes, metal powder, etc.; in the second slurry, the conductive agent may be acetylene black, Super P, etc.

[0071] In step S2 above, the first slurry is uniformly coated on at least one side of the current collector. The coating thickness matches the thickness design requirements of the first functional area. In some embodiments, the thickness of the first functional area after drying reaches 10μm~30μm. After coating, the first slurry layer is pre-dried to reach a semi-cured state. Pre-drying can be carried out by low-temperature short-time drying. The semi-cured state is when the surface of the slurry is dry, but the inside is not dry and still retains a small amount of solvent.

[0072] In step S3 above, a second slurry is applied onto the semi-cured first slurry layer. The coating thickness matches the design requirements of the second functional region. In some embodiments, the thickness of the second functional region after drying reaches 100μm~250μm. After coating, the second slurry is pre-dried to a semi-cured state to obtain a pre-dried double-layer coated zinc anode. Pre-drying can be performed using a low-temperature, short-time drying method. The semi-cured state is when the surface of the slurry is dry, but the interior is not dry and still retains a small amount of solvent.

[0073] In step S4 above, a flexible rubber roller is used to lightly roll the pre-dried double-layer coated zinc negative electrode, applying a low initial pressure. The flexible rubber roller can flexibly adapt to the surface morphology of the double-layer slurry, promoting mechanical interlocking of the two semi-cured wet films at the interface without damaging the overall coating structure. Simultaneously, the binder molecular chains begin to entangle, and the hydrogen-suppressing functional components undergo initial diffusion mediated by residual solvent at the interface, forming a continuous concentration gradient, eliminating interlayer voids, and achieving initial physical fusion of the interface. In some embodiments, exemplarily, the initial pressure of the flexible rubber roller is a linear pressure of 0.1 MPa to 0.6 MPa. In some embodiments, the flexible rubber roller uses rubber with a Shore hardness of 40 to 80 degrees. In some embodiments, the rolling time using the flexible rubber roller is controlled to be 30 seconds to 3 minutes, ensuring that the pressure is uniformly transmitted to the interface of the two slurry layers, allowing sufficient time for component diffusion and mechanical interlocking.

[0074] In step S5 above, the pre-pressed zinc anode after roll-pressing and fusion is thoroughly dried to remove the residual solvent inside the electrode. The binder molecules in the two slurries further diffuse and entangle with each other, while the hydrogen-suppressing functional components form a concentration gradient distribution, ultimately forming a continuous overall structure without a clear physical interface, achieving chemical bonding at the interface, and avoiding interface defects in multi-layer structures.

[0075] In step S6 above, a rigid pressure roller is used to perform final rolling pressing on the dried pre-pressed zinc anode under a second pressure, wherein the second pressure is greater than the first pressure. This linear pressure further densifies the composite functional layer, increases the packing density of the zinc-based active material, and strengthens the interlayer bonding strength, resulting in a zinc anode with a gradient distribution of hydrogen-suppressing functional components and a stable structure. In some embodiments, exemplarily, the second pressure of the rigid pressure roller is 1.5 MPa to 3.5 MPa.

[0076] The preparation method of this application embodiment achieves the non-uniform distribution of hydrogen-suppressing functional components in the electrode material layer through the above steps, eliminates interlayer interface defects that are easy to be generated by multilayer coating, and produces a zinc electrode with non-uniformly distributed hydrogen-suppressing additives, which improves the interface hydrogen suppression effect, increases the utilization rate of additives, effectively avoids electrode structure failure caused by hydrogen evolution bubbles, and at the same time improves the cycle stability and service life of the zinc negative electrode.

[0077] In some embodiments, when preparing the first slurry, the hydrogen-suppressing functional component, conductive agent, binder, and zinc-based active material are added to a solvent in a mass ratio of (40~60):(10~20):(10~30):(0~30) and mixed to achieve uniform dispersion. The zinc-based active material can be selectively added according to actual needs.

[0078] In some embodiments, when preparing the second slurry, the hydrogen-suppressing functional component, conductive agent, binder, and zinc-based active material are added to a solvent in a mass ratio of (0~5):(5~10):(10~20):(65~85) and mixed to achieve uniform dispersion. The hydrogen-suppressing functional component can be selectively added according to actual needs.

[0079] In some embodiments, the process conditions for pre-drying the coated first slurry to a semi-cured state are: a temperature of 60°C to 80°C and a drying time of 1 min to 5 min. Exemplarily, the temperature can be 60°C, 70°C, 80°C, etc., and the drying time can be 1 min, 2 min, 3 min, 4 min, 5 min, etc. In some embodiments, the wet film thickness of the first slurry is 20 μm to 60 μm. Hot air drying can be used as the drying method. The drying time can be flexibly adjusted according to the thickness of the slurry coating; the drying time should be appropriately reduced when the slurry coating is thin, and appropriately extended when the coating is thick. During production, the semi-cured state can be determined by visual appearance and touch: when the surface of the first slurry coating has no obvious liquid gloss, there is no stickiness when lightly touched with a finger, the coating as a whole is still in a soft state, and a small amount of solvent is still retained inside, and it is not completely hardened, it can be determined that a qualified semi-cured state has been reached.

[0080] In some embodiments, the process conditions for pre-drying the coated second slurry to a semi-cured state are: temperature 60°C~80°C, drying time 3min~8min. Exemplarily, the temperature can be 60°C, 70°C, 80°C, etc., and the drying time can be 3min, 4min, 5min, 6min, 7min, 8min, etc. Hot air drying can be used as the drying method.

[0081] In some embodiments, the process conditions for drying the pre-pressed zinc negative electrode are: a temperature of 90℃~120℃ and a drying time of 10min~30min. Exemplarily, the temperature can be 90℃, 100℃, 110℃, 120℃, etc., and the drying time can be 10min, 15min, 20min, 25min, 30min, etc. The drying method can be hot air drying, infrared heating, etc. The drying time is adjusted according to the overall thickness of the electrode material layer.

[0082] In some embodiments, the step of coating the second slurry onto the semi-cured first slurry layer and pre-drying the coated second slurry to a semi-cured state to obtain a pre-dried double-layer coated zinc anode includes:

[0083] The second slurry is coated onto the semi-cured first slurry layer;

[0084] Let it stand for 5 to 30 minutes in the range of 20℃ to 40℃;

[0085] The second slurry is pre-dried to a semi-cured state to obtain a pre-dried double-coated zinc anode.

[0086] In this embodiment, the electrode sheet coated with the second slurry is placed at room temperature (20°C to 40°C) for 5 to 30 minutes to promote full wetting and adhesion between the semi-dry first slurry layer and the wet second slurry layer, weakening the delamination interface between the two layers. Simultaneously, the slurry slowly self-levels, releasing internal stress generated during coating and preventing issues such as blistering, edge curling, and interlayer peeling during subsequent drying and rolling processes. After standing, the second slurry layer undergoes a low-temperature pre-drying treatment to smoothly transition to a semi-cured state, maintaining a continuous and interfacial transition between the two layers. In some embodiments, the wet film thickness of the second slurry is 200 μm to 500 μm.

[0087] In one embodiment, after the first slurry is coated and pre-dried to a semi-cured state, an elastic rubber roller with a uniformly raised surface is used to perform a light rolling treatment on the first slurry layer at a pressure of 0.05MPa to 0.5MPa, so that a micro-uneven morphology and a fine microporous structure are uniformly formed on the upper surface of the first slurry layer; this porous uneven surface layer can significantly increase the contact area between subsequent layers, which is conducive to the embedding and fusion of the second slurry material into the interlayer and eliminates the obvious physical interface between the two layers.

[0088] In some embodiments, the viscosity of the second slurry is lower than that of the first slurry, and the solvent content of the second slurry is 8% to 15% higher than that of the first slurry, which is more conducive to the leveling of the second slurry.

[0089] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be further described in detail below with reference to the accompanying drawings and several preferred embodiments. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. The parameter values ​​corresponding to the protection scope defined in this application have been exemplarily listed above. The reagents and raw materials used in the embodiments of this application are commercially available conventional products that can be obtained directly through commercial channels. For test methods in the following embodiments that do not specify specific conditions, the test methods in the embodiments are all performed under conventional conditions. Furthermore, the technical features involved in the various embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0090] Example 1

[0091] Nickel-plated steel strip with a thickness of 30μm was selected as the current collector.

[0092] Add 0.5% sodium dodecylbenzenesulfonate (SDBS) to deionized water and dissolve it completely. Then, add 50% Bi2O3 and 10% conductive graphite by mass of the total solids. After dispersion treatment, add 20% polyvinyl alcohol (PVA) and 5% sodium carboxymethyl cellulose (CMC) by mass of the total solids. Stir until homogeneous to obtain the first slurry.

[0093] Based on the total mass of solids, 65% zinc powder, 2% Bi2O3, 15% acetylene black, 13% PVA and 5% potassium polyacrylate (PAAK) are mixed, and deionized water is added and stirred until homogeneous to obtain the second slurry.

[0094] The first slurry was coated onto the surface of the nickel-plated steel strip to form a first wet film with a thickness of 20 μm, and then dried with hot air at 70°C for 2 min until it reached a semi-cured state.

[0095] A second slurry is coated on the semi-cured first wet film to form a second wet film. The total thickness of the two wet films is 320 μm. The film is then dried with hot air at 60°C for 5 min until it reaches a semi-cured state.

[0096] The double-layer semi-dry electrode sheet was lightly rolled and fused using an elastic rubber roller at a surface temperature of 50°C and a pressure of 0.3 MPa for 1 minute.

[0097] The zinc anode of Example 1 was then completely dried and cured at 120°C, and finally densified by pressing with a rigid roller at a pressure of 2.5 MPa.

[0098] Comparative Example 1

[0099] Nickel-plated steel strip with a thickness of 30μm was selected as the current collector.

[0100] Based on the total mass of solids, 65% zinc powder, 2% Bi2O3, 15% acetylene black, 13% PVA and 5% potassium polyacrylate (PAAK) are mixed, and deionized water is added and stirred until uniform to obtain a homogeneous slurry.

[0101] The homogeneous slurry was directly coated onto the surface of the current collector to form a wet film with a thickness of 300 μm; it was dried at a constant temperature of 120℃ and densified by pressing with a rigid roller at a pressure of 2.5 MPa to obtain the zinc anode of Comparative Example 1.

[0102] The zinc anodes obtained in Example 1 and Comparative Example 1 were used as working anodes, respectively. The theoretical areal capacity of the working anodes was approximately 42 mAh·cm⁻¹. -2 A polyolefin film (PP membrane) was selected to make the negative electrode separator bag, and the zinc negative electrode was inserted into it; a non-woven fabric (Hunan Yuanda New Materials Co., Ltd.) was selected to make the positive electrode separator bag, and the Ni(OH)2 electrode (Henan Xin'an Energy Technology Co., Ltd., with a theoretical areal capacity of approximately 47 mAh·cm⁻¹) was inserted into it. -2The Ni(OH)₂ electrode, zinc anode, and Ni(OH)₂ electrode, each encased in a separator bag, are stacked together to form a sandwich-structured single-cell battery. The electrolyte is a 6 mol / L potassium hydroxide aqueous solution saturated with zinc oxide, and the electrolyte volume for each cell is approximately 30 mL, thus completing the preparation of the zinc-nickel battery to be tested.

[0103] The battery cycle gas production was tested using the water displacement method, and the capacity retention rate at different cycle numbers was also tested. The battery performance of Example 1 and Comparative Example 1 was compared. It should be noted that the above two tests were conducted using independent batteries, and the batteries for each test were prepared in parallel under the same process conditions.

[0104] Specifically, the test method for the gas production volume of the cycle is as follows: connect the exhaust valve of the zinc battery to be tested to a graduated drainage and gas collection device (such as a syringe tube sealed at one end) through a conduit. After every 100 cycles, record the gas volume collected by the drainage and gas collection device, which is the gas production volume for the corresponding number of cycles.

[0105] The battery cycle testing method is as follows: Using the Xinwei Battery Testing System (Shenzhen Xinwei Electronics Co., Ltd.), the battery is subjected to charge-discharge cycle testing at a rate of 0.2C at room temperature: constant current and constant voltage charging to 1.9V, and constant current discharging to 1.3V. Continuous cycles are performed, and the discharge capacity during each cycle is recorded. The capacity retention rate is calculated by dividing the discharge capacity of the Nth cycle by the discharge capacity of the first cycle, and the coulombic efficiency is calculated by dividing the discharge capacity of the Nth cycle by the charging capacity of the Nth cycle.

[0106] The test results of the circulating gas production are shown in Table 1.

[0107] Table 1

[0108]

[0109] As shown in Table 1, the zinc anode prepared in Example 1 exhibits significant advantages over Comparative Example 1 in both hydrogen evolution suppression and cycle stability. Specifically, the gas production of Example 1 after 100, 200, and 300 cycles was 1.2 mL, 2.4 mL, and 4.6 mL, respectively, all significantly lower than the 3.8 mL, 8.5 mL, and 13.3 mL of Comparative Example 1 at the same time. After 300 cycles, the cumulative gas production of Example 1 was only 34.6% of that of Comparative Example 1, effectively suppressing internal gas production, reducing safety hazards caused by gas expansion, and improving the safety and reliability of the battery.

[0110] The battery cycle test results of Example 1 and Comparative Example 1 are as follows: Figure 3 As shown. By Figure 3It can be seen that the battery of Example 1 retains approximately 96% capacity after 100 cycles and maintains approximately 94% capacity after 200 cycles, exhibiting a smaller capacity decay and excellent cycle stability. In contrast, the battery of Comparative Example 1 retains approximately 93% capacity after 100 cycles, but the capacity retention drops to approximately 88% after 200 cycles, showing a significantly increased capacity decay. These results indicate that the battery of Example 1 has significantly better cycle stability than that of Comparative Example 1. This may be attributed to the zinc anode of Example 1 effectively suppressing the hydrogen evolution side reaction during cycling, reducing the shedding of active material and electrode structure degradation caused by gas evolution, thereby improving electrode structure stability and achieving a better long-cycle capacity retention.

[0111] The batteries from Example 1 and Comparative Example 1 were disassembled after 200 cycles, and the surface condition of the zinc negative electrode and the corresponding separator was photographed. The results are as follows. Figure 4 and Figure 5 As shown. By Figure 4 As can be seen, the zinc negative electrode surface in Example 1 is generally smooth and dense, with the active material tightly bonded to the current collector, and no obvious detachment is observed; the corresponding separator surface is clean, with no negative electrode active material adhering, indicating that the hydrogen-suppressing coating effectively maintains the integrity of the electrode structure. It should be noted that the white area in the central region of the negative electrode is not material detachment, but rather due to insufficient participation of the central part of the electrode in the electrochemical reaction. Figure 5 It can be seen that the zinc anode active material in Comparative Example 1 has suffered severe detachment, with exposed current collectors visible at the electrode edges, and the electrode surface is uneven with poor structural integrity. Correspondingly, a large amount of detached anode active material adheres to the surface of the separator, indicating that the electrode structure has significantly deteriorated during cycling. The comparison results show that the introduction of the hydrogen-suppressing coating effectively inhibits the detachment of active material caused by hydrogen evolution side reactions during cycling, and significantly improves the structural stability of the zinc anode.

[0112] In summary, the zinc anode of this application can synergistically achieve efficient hydrogen evolution suppression and long-term cycle stability, and its overall electrochemical performance is significantly better than that of traditional zinc anodes.

[0113] Obviously, the embodiments described above are only some embodiments of this application, not all embodiments. The accompanying drawings show preferred embodiments of this application, but do not limit the patent scope of this application. This application can be implemented in many different forms; rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the disclosure of this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments, or make equivalent substitutions for some of the technical features. Any equivalent structures made using the content of this application's specification and drawings, directly or indirectly applied to other related technical fields, are similarly within the scope of patent protection of this application.

Claims

1. A zinc negative electrode with hydrogen suppression function, characterized in that, The device includes a current collector and an electrode material layer coated on at least one side of the current collector; the electrode material layer comprises a zinc-based active material, a conductive agent, a binder, and a hydrogen-suppressing functional component, wherein the hydrogen-suppressing functional component is selected from at least one of the oxides, sulfides, and hydroxides corresponding to one or more metal elements selected from bismuth, selenium, tin, indium, lead, and cadmium; In the electrode material layer, the hydrogen suppression functional component is non-uniformly distributed, and the content of the hydrogen suppression functional component on the side closer to the current collector is higher than the content on the side farther away from the current collector.

2. The zinc negative electrode with hydrogen suppression function as described in claim 1, characterized in that, The zinc-based active material is one or more of zinc powder and zinc alloy powder; the conductive agent is selected from one or more of acetylene black, Super P, carbon nanotubes, graphene, conductive graphite, and metal powder; the binder is selected from one or more of polyvinyl alcohol, sodium carboxymethyl cellulose, polyvinylidene fluoride, and styrene-butadiene rubber; and the current collector is selected from one of nickel-plated steel strip and copper foil.

3. The zinc anode with hydrogen suppression function according to claim 1, characterized in that, The hydrogen-suppressing functional component accounts for 40% to 60% of the mass on the side closer to the current collector, and 0% to 5% of the mass on the side farther from the current collector. The mass percentage of the hydrogen-suppressing functional component is distributed in a gradient from the side closer to the current collector to the side farther from the current collector.

4. The zinc negative electrode with hydrogen suppression function according to claim 1, characterized in that, The electrode material layer includes a first functional region close to the current collector and a second functional region far from the current collector. The mass percentage of the hydrogen inhibition functional component in the first functional region is 40% to 60%, and the mass percentage of the hydrogen inhibition functional component in the second functional region is 0% to 5%. The area between the first functional region and the second functional region is an intermediate region where the mass percentage of the hydrogen inhibition functional component is gradient.

5. The zinc negative electrode with hydrogen suppression function according to claim 4, characterized in that, The thickness of the first functional region is 10μm~25μm; the thickness of the second functional region is 100μm~250μm.

6. A method for preparing a zinc anode with hydrogen suppression function, used to prepare the zinc anode with hydrogen suppression function as described in any one of claims 1 to 5, characterized in that, The preparation method includes: A first slurry and a second slurry are prepared, wherein the first slurry comprises a conductive agent, a binder, a hydrogen-suppressing functional component, a solvent, and an optional zinc-based active material, and the second slurry comprises a conductive agent, a binder, a zinc-based active material, a solvent, and an optional hydrogen-suppressing functional component; the content of the hydrogen-suppressing functional component in the first slurry is higher than the content of the hydrogen-suppressing functional component in the second slurry, and the mass percentage of the zinc-based active material in the first slurry is lower than the mass percentage of the zinc-based active material in the second slurry; The first slurry is applied to at least one side of the current collector surface, and the applied first slurry is pre-dried to a semi-cured state; The second slurry is coated onto the semi-cured first slurry layer, and the coated second slurry is pre-dried to a semi-cured state to obtain a pre-dried double-coated zinc anode. The pre-dried double-coated zinc anode is fused by rolling with an elastic rubber roller under the first pressure to obtain a pre-pressed zinc anode. Dry the pre-pressed zinc negative electrode; The dried pre-pressed zinc anode is rolled with a rigid pressure roller at a second pressure greater than the first pressure to obtain the zinc anode with hydrogen suppression function.

7. The method for preparing a zinc anode with hydrogen suppression function as described in claim 6, characterized in that, The solvent is selected from organic solvents or water, and the solvent of the first slurry is the same as that of the second slurry. The binder is selected from one or more of polyvinyl alcohol, sodium carboxymethyl cellulose, polyvinylidene fluoride, and styrene-butadiene rubber. And / or, the zinc-based active material is one or more of zinc powder and zinc alloy powder; And / or, the conductive agent is selected from one or more of acetylene black, Super P, carbon nanotubes, graphene, conductive graphite, and metal powder.

8. The method for preparing a zinc anode with hydrogen suppression function as described in claim 6, characterized in that, When preparing the first slurry, the hydrogen-inhibiting functional component, conductive agent, binder, and zinc-based active material are added to the solvent in a mass ratio of (40~60):(10~20):(10~30):(0~30) and mixed to disperse evenly; And / or, when preparing the second slurry, the hydrogen-inhibiting functional component, conductive agent, binder, and zinc-based active material are added to the solvent in a mass ratio of (0~5):(5~10):(10~20):(65~85) and mixed to disperse evenly.

9. The method for preparing a zinc anode with hydrogen suppression function as described in claim 6, characterized in that, The process conditions for pre-drying the coated first slurry to a semi-cured state are: temperature 60℃~80℃, drying time 1min~5min; And / or, the process conditions for pre-drying the coated second slurry to a semi-cured state are: temperature 60℃~80℃, drying time 3min~8min; And / or, the process conditions for drying the pre-pressed zinc negative electrode are: temperature 90℃~120℃, drying time 10min~30min.

10. The method for preparing a zinc anode with hydrogen suppression function as described in claim 6, characterized in that, The step of coating the second slurry onto the semi-cured first slurry layer and pre-drying the coated second slurry to a semi-cured state to obtain a pre-dried double-layer coated zinc anode includes: The second slurry is coated onto the semi-cured first slurry layer; Let it stand for 5 to 30 minutes in the range of 20℃ to 40℃; The second slurry is pre-dried to a semi-cured state to obtain a pre-dried double-coated zinc anode.

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