Secondary battery electrode preparation method and aqueous secondary battery

Abstract

The invention discloses a secondary battery electrode preparation method and an aqueous secondary battery. The method comprises the following steps: mixing an electrode active material, a conductive material with a high length-diameter ratio structure, a conductive agent and a layered structure compound to obtain a mixed material; the layered structure compound has an interlayer structure capable of providing an ion transmission channel and buffering volume change in the charging and discharging process; the length-diameter ratio of the conductive material with the high length-diameter ratio structure is greater than 3: 1; compounding a binder with the mixed material to enable the binder to be distributed in the mixed material to obtain a composite material; carrying out molding treatment on the composite material to obtain a pole piece blank; and treating the pole piece blank body to enable the binder to form a three-dimensional bonding network to obtain the secondary battery electrode, wherein the compound with the layered structure and the conductive material with the high length-diameter ratio structure have a synergistic effect, and the electrochemical performance of the electrode is improved from the aspects of ion transmission, volume stability and electronic conductivity respectively.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a method for preparing a secondary battery electrode and an aqueous secondary battery. Background Technology

[0002] Zinc-nickel batteries have broad application prospects in the field of energy storage due to their advantages such as high energy density, high safety, and environmental friendliness. Their positive electrode active material is typically nickel hydroxide, which stores and releases energy through a reversible phase transition between Ni(OH)₂ and NiOOH during charging and discharging.

[0003] However, existing zinc-nickel batteries face a key technical bottleneck that has long remained unresolved in practical applications: the structural degradation of the cathode material during repeated charge-discharge cycles. This problem directly results in the battery's cycle life being far below market expectations, severely hindering its commercialization process.

[0004] The root of the aforementioned technical problems lies in the intrinsic physicochemical properties of the positive electrode active material. During charging, Ni(OH)₂ transforms into NiOOH, accompanied by significant changes in the crystal structure and a volume expansion of approximately 15-20%; during discharging, the reverse process occurs, resulting in volume contraction. This "breathing effect," which occurs in each cycle, generates enormous and repetitive mechanical stress within the electrode's microstructure. With the accumulation of cycles, this continuous stress leads to a series of irreversible physical damages: first, the active material particles themselves are prone to cracking and breaking, gradually "pulverizing"; second, the pulverized fine particles gradually lose effective electrical contact with surrounding particles and the conductive agent; finally, the entire active material layer may peel off from the current collector.

[0005] This gradual structural degradation disrupts the stable channels necessary for electron and ion transport within the electrode. Once the conductive network is interrupted, some of the active material becomes "dead matter," unable to participate in electrochemical reactions, leading to a continuous decline in the battery's effective capacity. Although existing technologies attempt to construct electrodes using conventional conductive agents and binders, these materials often cannot withstand the mechanical impact of such drastic volume changes over long periods, failing to fundamentally suppress the pulverization and shedding of active material.

[0006] The above content is only used to assist in understanding the technical solution of the invention and does not imply acceptance that the above content is prior art. Summary of the Invention

[0007] The main objective of this invention is to provide a method for preparing a secondary battery electrode and an aqueous secondary battery, which aims to improve the cycle life of the electrode.

[0008] To achieve the above objectives, the present invention proposes a method for preparing a secondary battery electrode, comprising the following steps: Step S1: Mix the electrode active material, the conductive material with a high aspect ratio structure, the conductive agent, and the layered structure compound to obtain a mixture; the layered structure compound has an interlayer structure that can provide ion transport channels and buffer volume changes during charging and discharging; the aspect ratio of the conductive material with a high aspect ratio structure is greater than 3:1; Step S2: Combine the binder with the mixture to distribute the binder throughout the mixture, thereby obtaining a composite material; Step S3: The composite material is molded to obtain an electrode preform; Step S4: Process the electrode blank to form a three-dimensional bonding network with the binder, thereby obtaining a secondary battery electrode; The layered compound and the high aspect ratio conductive material work synergistically to improve the electrochemical performance of the electrode in terms of ion transport, volume stability and electronic conductivity, respectively.

[0009] In one embodiment, the layered compound is selected from at least one of metal hydroxides, layered double hydroxides, layered metal oxides, or layered metal sulfides; the layered compound is preferably a compound having a two-dimensional layered crystal structure, wherein the layers are bonded by hydrogen bonds or van der Waals forces.

[0010] In one embodiment, the layered compound is at least one of bismuth hydroxide, magnesium hydroxide, aluminum hydroxide, cobalt hydroxide, manganese hydroxide, or a complex hydroxide thereof; the layered compound is present in the mixture at a mass percentage of 0.5% to 10%.

[0011] In one embodiment, the conductive material with a high aspect ratio structure is at least one of metal powder, carbon fiber, carbon nanotube, metal nanowire or conductive polymer fiber; the conductive material with a high aspect ratio structure is preferably a material with a chain-like, fibrous or dendritic morphology, which can form a three-dimensional conductive network in the electrode.

[0012] In one embodiment, the metal powder is nickel powder, cobalt powder, copper powder, silver powder, or an alloy powder thereof; the metal powder has a spherical, dendritic, or fibrous structure with an aspect ratio of 5:1 to 20:1, and its mass percentage in the mixture is 3% to 15%.

[0013] In one embodiment, the mixing process in step S1 is carried out under a protective atmosphere or vacuum, and is performed by at least one of mechanical mixing, ball milling, high-energy ball milling or air jet milling; a dispersing agent may be added during the mixing process, and the amount of the dispersing agent added is 0.05% to 1% of the total mass of the mixture.

[0014] In one embodiment, the binder in step S2 is a thermoplastic polymer or a thermosetting polymer; the thermoplastic polymer includes polytetrafluoroethylene, polyvinylidene fluoride, polyethylene or copolymers thereof; the binder is compounded with the mixture by means of powder mixing, emulsion dispersion or solution impregnation.

[0015] In one embodiment, the molding process in step S3 includes at least one of compression molding, extrusion molding, roll forming, or injection molding; the molding pressure is 5 to 30 MPa, and the density of the molded electrode preform is 60% to 95% of the target theoretical density.

[0016] In one embodiment, the treatment in step S4 includes at least one of heat treatment, radiation treatment, or chemical crosslinking treatment; when heat treatment is used, the treatment temperature is above the glass transition temperature of the adhesive to below its decomposition temperature, and the treatment time is 0.5 to 5 hours.

[0017] The present invention also proposes an aqueous secondary battery, wherein the aqueous secondary battery includes the electrode prepared by the above method; the aqueous secondary battery is an alkaline secondary battery, a neutral aqueous battery, or a weakly acidic aqueous battery; the alkaline secondary battery includes a zinc-nickel battery, a zinc-manganese battery, a nickel-metal hydride battery, or a nickel-cadmium battery.

[0018] The secondary battery electrode preparation method provided by this invention achieves a breakthrough improvement in the overall performance of the electrode through the synergistic mechanism of layered compound and high aspect ratio conductive material. The interlayer structure of the layered compound provides a low-barrier channel for ion transport, and its adjustable interlayer spacing allows it to adapt to the volume changes of the active material through interlayer expansion and contraction during charging and discharging, fundamentally solving the structural stability problem during electrode cycling. The high aspect ratio conductive material (greater than 3:1) constructs an interconnected three-dimensional conductive network within the electrode, ensuring rapid electron transport throughout the entire electrode system. Simultaneously, its unique morphology provides necessary mechanical support for the electrode, effectively suppressing the pulverization and shedding of the active material during cycling. The technical advantage of this dual-component synergistic mechanism lies in the simultaneous optimization of ion transport, electronic conductivity, and structural stability. Practical applications show that the electrode prepared using this method can improve the utilization rate of the active material by more than 15 percentage points, and the capacity retention rate after 100 cycles exceeds 90%, which is 30 percentage points higher than traditional methods. The three-dimensional network formed by the binder through specific treatment further enhances the integrity of the electrode, making the first-cycle coulombic efficiency close to 98%, which fully verifies the significant technical effect of this method in improving the performance of secondary battery electrodes. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the dry cathode of the present invention; Figure 2 The battery cycle comparison curves are for Examples 1-3 and Comparative Examples 1-3 of the present invention. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] It should be noted that the meaning of "and / or" throughout the text includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or a solution that satisfies both A and B. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0024] The terms “comprising,” “including,” “containing,” “containing,” “having,” or other variations thereof are intended to cover non-closed inclusion, and no distinction is made between these terms. The term “comprising” means that other steps and components may be added without affecting the final result. The term “comprising” also includes the terms “consistently composed of” and “substantially composed of”. The compositions and methods / processes of the present invention comprise, consist of, and substantially consist of the essential elements and limitations described herein, as well as any additional or optional components, parts, steps, or limitations described herein. All numerical values ​​or expressions relating to component amounts, process conditions, etc., used in the specification and claims are to be understood in all cases to be modified by “about.” All ranges relating to the same component or property include endpoints that can be combined independently. Because these ranges are continuous, they include every value between a minimum and a maximum value. It should also be understood that any numerical range referenced in this application is intended to include all subranges within that range. As used herein, “parts by weight,” “number of parts by weight,” “mass parts,” or “mass parts” are used interchangeably. A part by weight can be any fixed weight expressed in milligrams, grams, or kilograms (e.g., 1 mg, 1 g, 2 g, 5 g, or 1 kg). For example, a composition consisting of 1 part by weight of component a and 9 parts by weight of component b can be a composition consisting of 1 gram of component a + 9 grams of component b, or 10 grams of component a + 90 grams of component b, etc.

[0025] Zinc-nickel batteries, as an important alkaline secondary battery system, have shown broad application prospects in power tools, consumer electronics, and large-scale energy storage due to their outstanding advantages such as high operating voltage, high energy density, good safety, and environmental friendliness. In zinc-nickel battery systems, nickel hydroxide (e.g., spherical nickel hydroxide) is typically used as the main active material at the positive electrode. The charging and discharging process of the battery relies on the reversible redox reaction between Ni(OH)₂ and NiOOH in the positive electrode active material, thereby achieving the storage and release of chemical and electrical energy.

[0026] To further improve the overall performance of zinc-nickel batteries and meet the growing market demand, existing technologies have conducted extensive research on the modification of cathode materials and their preparation processes. For example, some studies have attempted to improve performance by optimizing electrode preparation processes. Chinese patent application CN115579530A discloses a dry method for preparing aqueous sodium-ion battery electrodes, which aims to simplify the process and reduce environmental impact by avoiding the use of organic solvents. Despite these advancements, cathode materials and their preparation technologies for zinc-nickel batteries still face several severe and interconnected technical bottlenecks, significantly hindering their commercial application.

[0027] First, the structural instability of the cathode material is one of its core challenges. During repeated charge-discharge cycles, the nickel hydroxide active material undergoes significant phase transformations and volume changes. This inevitable volume expansion and contraction generates enormous mechanical stress within the electrode, which over time leads to the microstructure of the active material particles breaking down, pulverizing, and even peeling off from the current collector. This progressive structural degradation undermines the physical integrity of the electrode and causes the conductive network to break down, which is one of the fundamental reasons for the rapid decline in battery capacity. Existing technologies lack an effective mechanism to buffer or suppress this volume effect driven by electrochemical reactions.

[0028] Secondly, short cycle life is another key obstacle limiting the large-scale application of zinc-nickel batteries. Besides the loss of active material due to structural instability, the degradation of electrode cycle performance is also related to the deterioration of the internal microenvironment. With increasing cycle count, the electrode pore structure may collapse, hindering effective electrolyte wetting and ion transport, creating "dead zones" that prevent some active materials from participating in electrochemical reactions. Especially under high-rate, high-current charge-discharge conditions, polarization intensifies, further reducing the utilization rate of active materials and making capacity decay particularly prominent, resulting in a battery's effective lifespan far below theoretical expectations.

[0029] Furthermore, interfacial side reactions and slow reaction kinetics also severely impact battery performance and safety. When charging to higher voltages, oxygen evolution inevitably occurs on the positive electrode side, while hydrogen evolution is prone to occur on the negative electrode side. These parasitic reactions not only consume the limited aqueous electrolyte, leading to increased internal battery pressure and potential safety hazards, but more importantly, they cause irreversible loss of active materials, reducing the battery's coulombic efficiency and energy efficiency. From a kinetic perspective, the diffusion rate of zinc ions or related protons in solid-phase positive electrode materials is relatively slow, with a high diffusion barrier. This directly limits the rate performance of the electrode, making it difficult for the battery to perform well in high-power applications requiring rapid charging and discharging.

[0030] In existing technologies, researchers have attempted to address these issues by introducing various additives into the cathode material. For example, adding conductive agents such as carbon materials can construct a better electronic conductivity network, but its effectiveness in mitigating the volume expansion and structural pulverization of the active material is limited. Similarly, introducing certain polymer binders or inorganic substances as structural stabilizers can enhance the mechanical strength of the electrode to some extent, but these additives themselves often lack excellent ionic or electronic conductivity; excessive addition may actually increase the internal resistance of the electrode, sacrificing the battery's kinetic performance. Therefore, most improvement schemes can only address a single problem specifically, making it difficult to achieve a synergistic improvement in multiple aspects such as electrode structural stability, cycle life, rate performance, and suppression of side reactions.

[0031] In conclusion, there is an urgent need to develop a novel zinc-nickel battery cathode material technology. This solution should, through innovative material design and process optimization, construct a multifunctional composite electrode system integrating an excellent electronic conductivity network, efficient ion transport channels, a robust mechanical support structure, and an effective volume change buffering mechanism. This would comprehensively address many issues existing in the stability, cycle life, and kinetic performance of current zinc-nickel battery cathode materials, and promote the practical application of high-performance zinc-nickel battery technology.

[0032] In related technologies, although attempts have been made to improve the performance of cathode materials by adding various modifiers, most solutions only address a single problem and fail to achieve synergistic improvements in multiple performance aspects. For example, while simply adding conductive agents can improve the conductivity of the electrode, its effect on suppressing volume changes and improving structural stability is limited. Conversely, adding certain structural stabilizers can alleviate volume expansion to some extent, but may reduce the conductivity or ion transport efficiency of the electrode.

[0033] In response, this invention proposes a method for preparing a secondary battery electrode.

[0034] In this embodiment of the invention, the method for preparing the secondary battery electrode includes the following steps: Step S1: Mix the electrode active material, the conductive material with a high aspect ratio structure, the conductive agent, and the layered structure compound to obtain a mixture; the layered structure compound has an interlayer structure that can provide ion transport channels and buffer volume changes during charging and discharging; the aspect ratio of the conductive material with a high aspect ratio structure is greater than 3:1; Step S2: Combine the binder with the mixture to distribute the binder throughout the mixture, thereby obtaining a composite material; Step S3: The composite material is molded to obtain an electrode preform; Step S4: Process the electrode blank to form a three-dimensional bonding network with the binder, thereby obtaining a secondary battery electrode; The layered compound and the high aspect ratio conductive material work synergistically to improve the electrochemical performance of the electrode in terms of ion transport, volume stability and electronic conductivity, respectively.

[0035] This secondary battery electrode achieves simultaneous optimization of ion transport, electronic conductivity, and structural stability through the synergistic mechanism of layered compound and high aspect ratio conductive material.

[0036] The secondary battery electrode preparation method provided by this invention achieves a breakthrough improvement in the overall performance of the electrode through the synergistic mechanism of layered compound and high aspect ratio conductive material. The interlayer structure of the layered compound provides a low-barrier channel for ion transport, and its adjustable interlayer spacing allows it to adapt to the volume changes of the active material through interlayer expansion and contraction during charging and discharging, fundamentally solving the structural stability problem during electrode cycling. The high aspect ratio conductive material (greater than 3:1) constructs an interconnected three-dimensional conductive network within the electrode, ensuring rapid electron transport throughout the entire electrode system. Simultaneously, its unique morphology provides necessary mechanical support for the electrode, effectively suppressing the pulverization and shedding of the active material during cycling. The technical advantage of this dual-component synergistic mechanism lies in the simultaneous optimization of ion transport, electronic conductivity, and structural stability. Practical applications show that the electrode prepared using this method can improve the utilization rate of the active material by more than 15 percentage points, and the capacity retention rate after 100 cycles exceeds 90%, which is 30 percentage points higher than traditional methods. The three-dimensional network formed by the binder through specific treatment further enhances the integrity of the electrode, making the first-cycle coulombic efficiency close to 98%, which fully verifies the significant technical effect of this method in improving the performance of secondary battery electrodes.

[0037] There are various types of layered compound structures. In one embodiment, the layered compound is selected from at least one of metal hydroxides, layered double hydroxides, layered metal oxides, or layered metal sulfides. Preferably, the layered compound has a two-dimensional layered crystal structure, with its layers bonded by hydrogen bonds or van der Waals forces.

[0038] Further, in one embodiment, the layered compound is at least one of bismuth hydroxide, magnesium hydroxide, aluminum hydroxide, cobalt hydroxide, manganese hydroxide, or a complex hydroxide thereof; the mass percentage of the layered compound in the mixture is 0.5% to 10%.

[0039] These materials share a common characteristic: a two-dimensional layered structure. The layers are held together by weak hydrogen bonds or van der Waals forces, allowing them to buffer electrode volume expansion during charge and discharge through reversible changes in interlayer spacing. Magnesium hydroxide has an interlayer spacing of 0.477 nm and exhibits good stability in alkaline electrolytes. Aluminum hydroxide exists in various crystal forms, among which boehmite has a typical layered structure with an interlayer spacing of 0.6 nm, providing wider ion transport channels. Although cobalt hydroxide is more expensive, its electrochemical activity allows it to contribute additional capacity while providing structural support.

[0040] In one embodiment, the range of high aspect ratio conductive materials includes various metal powders and carbon-based materials. The high aspect ratio conductive material is at least one of metal powder, carbon fiber, carbon nanotube, metal nanowire, or conductive polymer fiber; preferably, the high aspect ratio conductive material has a chain-like, fibrous, or dendritic morphology, enabling it to form a three-dimensional conductive network in the electrode.

[0041] The high aspect ratio conductive material forms a three-dimensional network framework in the mixture, which physically separates the particles of the layered compound, thereby inhibiting its agglomeration during mixing and molding.

[0042] Further, in one embodiment, the metal powder is nickel powder, cobalt powder, copper powder, silver powder or alloy powder thereof; the metal powder has a spherical chain-like, dendritic or fibrous structure, with an aspect ratio of 5:1 to 20:1, and a mass percentage of 3% to 15% in the mixture.

[0043] Dendritic copper powder, prepared via electrolysis, possesses a highly branched three-dimensional structure with an aspect ratio exceeding 10:1. Its conductivity surpasses that of nickel powder, but its stability in alkaline environments requires special attention. While fibrous silver powder is more expensive, its excellent conductivity and chemical stability give it a unique advantage in high-end applications. Carbon-based materials, such as vapor-grown carbon fibers and multi-walled carbon nanotubes, not only exhibit excellent conductivity but also good chemical inertness, remaining stable even in harsh electrochemical environments.

[0044] In one embodiment, the mixing process in step S1 is carried out under a protective atmosphere or vacuum, and is performed by at least one of mechanical mixing, ball milling, high-energy ball milling or air jet milling; a dispersing agent may be added during the mixing process, and the amount of the dispersing agent added is 0.05% to 1% of the total mass of the mixture.

[0045] Step S1 specifically includes: Electrode active materials, conductive materials with high aspect ratio structures, conductive agents, layered compounds, and dispersing agents are placed in a mixing device for dry mixing according to a predetermined ratio. In a preferred embodiment, 72.30% by mass of nickel-based active material FC09, 7.30% by mass of spherical chain-like T255 nickel powder, 6.60% by mass of multi-walled carbon nanotubes as conductive agents, 1.80% by mass of bismuth hydroxide as a layered compound, and 0.1% by mass of dispersing agents are added to a planetary ball mill. The entire mixing process is carried out under an argon protective atmosphere to prevent oxidation or moisture absorption of the materials during mixing.

[0046] In different embodiments of the present invention, the electrode active material is not limited to FC09 in the above embodiments, but can also be other nickel-based cathode materials well known to those skilled in the art, such as, but not limited to: zinc-added spherical nickel hydroxide such as Zn3Co1.3, Zn4Co1.3, etc., and cobalt-coated nickel hydroxide such as Zn4Co1.3-Co3.5, Cd3Co1-Co3, etc. Accordingly, if the present invention is used to prepare a cathode, the active material of the cathode material can be selected from zinc oxide, zinc powder cathode, calcium zincate, etc.

[0047] Regarding the selection of electrode active materials, this invention can use various nickel-based compounds as positive electrode active materials. Among them, zinc-added spherical nickel hydroxide is one of the preferred material systems. This type of material is prepared by co-precipitation, where zinc and cobalt ions are co-incorporated into the nickel hydroxide lattice to form a uniform solid solution structure. Typical zinc-added materials include two formulations: Zn3Co1.3 and Zn4Co1.3, where the numbers represent the molar percentage of each metal element. The Zn3Co1.3 material contains 3% zinc and 1.3% cobalt. This optimized ratio effectively suppresses oxygen evolution side reactions during charging while maintaining high electrochemical capacity. When the zinc content is increased to 4%, i.e., the Zn4Co1.3 formulation, the overcharge performance of the material is further improved, with the charging efficiency increasing from 94% to over 96%. The theoretical specific capacities of these two materials are 285 mAh / g and 282 mAh / g, respectively, and the discharge specific capacity in practical applications typically reaches over 85% of the theoretical value.

[0048] Cobalt-coated spherical nickel hydroxide represents another important class of positive electrode active materials. These materials employ a core-shell structure design, with a core of doped and modified nickel hydroxide and an outer shell of cobalt hydroxide or cobalt oxide coating. Zn4Co1.3-Co3.5 is a typical cobalt-coated material, with a Zn4Co1.3 matrix and a 3-5 nm thick cobalt compound layer coated on the surface using chemical plating or electroplating processes, containing 3.5% cobalt. Another representative material, Cd3Co1-Co3, employs a cadmium-cobalt dual-doping strategy, with a 3% cadmium and 1% cobalt content in the matrix and a 3% cobalt content in the surface coating. The technical advantage of the cobalt coating lies in its preferential oxidation during the initial charging stage to form a highly conductive CoOOH phase, providing a good electron transport channel for the subsequent nickel hydroxide oxidation reaction. This design, together with the T255 nickel powder of this invention, forms a dual conductive network, producing a significant synergistic enhancement effect.

[0049] In addition to the aforementioned FC09 material, this invention can also utilize other commercially available nickel-based active materials, including the SP series from Tanaka Precious Metals of Japan and the HE series from Umicore of Belgium. These materials each have their own characteristics and can be selected based on the specific application of the battery. For example, for applications requiring high energy density, materials with higher cobalt content are preferred; for cost-sensitive applications, formulations with higher zinc content and lower cobalt content can be selected.

[0050] The choice of anode material system has a significant impact on the overall battery performance. Zinc oxide is the most traditional and mature anode material, and its reaction mechanism in alkaline electrolytes has been well studied. Commercial zinc oxide is usually produced using indirect or direct methods, achieving a purity of over 99.5%. Key technical parameters include specific surface area, typically controlled within the range of 3 to 15 square meters per gram. Excessively high specific surface area leads to increased self-discharge, while too low an area affects reaction kinetics. Particle size distribution is also an important parameter; D50 is typically controlled within 1 to 3 micrometers. Overly fine particles tend to agglomerate, while overly coarse particles result in incomplete reactions.

[0051] Zinc powder, as a negative electrode material, possesses higher theoretical capacity and better rate performance. Commercial zinc powder is prepared through atomization, distillation, or electrolysis, each with its own characteristics. Atomized zinc powder particles are spherical, have good flowability, and are suitable for slurry coating processes. Distilled zinc powder has high purity but higher cost. Electrolytic zinc powder has a dendritic structure, large specific surface area, and high reactivity, but relatively poor stability. Surface treatment of zinc powder is a key technology; common methods include coating with organic corrosion inhibitors and metal alloying. Organic corrosion inhibitors such as polyethylene glycol and polyvinyl alcohol can form a protective film on the zinc powder surface, inhibiting hydrogen evolution. Alloying treatment, by adding small amounts of metals such as indium, bismuth, and lead, alters the electrochemical behavior of zinc and improves corrosion resistance.

[0052] Calcium zincate, as a novel anode material, possesses unique crystal structure and reaction mechanism, giving it significant advantages in suppressing dendrite growth and improving cycle life. The synthesis of calcium zincate typically employs a chemical precipitation method, reacting calcium hydroxide with zinc oxide under specific conditions. Parameters such as reaction temperature, pH, and reaction time significantly influence the crystal form and performance of the product. Optimized synthesis conditions include a temperature of 60–80 degrees Celsius, a pH of 13–14, and a reaction time of 4–6 hours. The resulting calcium zincate exhibits a regular crystal morphology, uniform particle size distribution, and stable electrochemical performance.

[0053] The control of mixing process parameters has a decisive impact on the final mixing effect. Zirconia balls are preferred as the milling media, as their high hardness and chemical inertness ensure the efficiency and purity of the mixing process. The ball-to-material mass ratio is controlled within the range of 10:1 to 15:1, a ratio that ensures sufficient grinding effect while avoiding material performance degradation due to over-grinding. The ball mill speed is set to 500 rpm, at which speed sufficient mixing and appropriate refining of the materials can be achieved. The ball milling time is controlled at 2 hours, and precise time control ensures that the particle size distribution of the mixture is below 50 micrometers, guaranteeing uniform dispersion of each component at the microscale.

[0054] The selection and use of dispersing agents play a crucial role in the mixing effect. Dispersing agents can be selected from one or more combinations of ethanol, isopropanol, glycerol, or polyethylene glycol. These dispersing agents can reduce the surface tension between particles, prevent the agglomeration of fine particles such as bismuth hydroxide, and promote the uniform distribution of spherical chain nickel powder in the mixing system. The dispersing agent is added simultaneously with other materials during the dry material premixing stage, and achieves full contact and interaction with the solid materials through the ball milling process.

[0055] The precisely controlled mixing process described above ensures that the layered bismuth hydroxide compound is uniformly dispersed within the active material matrix. Simultaneously, the high aspect ratio T255 nickel powder forms a preliminary network framework structure, laying a solid foundation for subsequent binder coating and molding processes. The uniform microstructure formed during the mixing process is a prerequisite for the synergistic effect between the layered compound and the high aspect ratio conductive material.

[0056] In this embodiment, the electrode active material is the commercially available FC09 material, which is a specially modified nickel-based compound that has wide applications in the field of zinc-nickel battery cathode materials.

[0057] FC09 is a zinc-added spherical nickel hydroxide material with a precisely controlled chemical composition. The mass ratio of nickel, cobalt, and zinc is 54:4:4. This specific elemental ratio is the result of extensive research and optimization, providing good structural stability while maintaining high electrochemical activity. Nickel, as the main electrochemically active element, achieves charge storage during charge and discharge through the reversible conversion between divalent and trivalent nickel. The incorporation of cobalt primarily improves the material's conductivity and stabilizes the crystal structure, effectively enhancing the electrode's performance under high-rate charge and discharge conditions. The addition of zinc suppresses oxygen evolution side reactions during charging, improving charging efficiency and enhancing the material's cycle stability.

[0058] From a microstructural perspective, FC09 exhibits a typical spherical morphology with uniform particle size distribution, demonstrating good flowability and packing density. The advantage of this spherical structure lies in its ability to achieve high-density filling of the electrode material, increasing the content of active material per unit volume and thus improving the volumetric energy density of the battery. The relatively smooth surface of the spherical particles facilitates good contact with conductive agents and binders during electrode fabrication, contributing to the construction of a stable electrode structure.

[0059] The FC09 material exhibits a β-type nickel hydroxide crystal structure with hexagonal layered characteristics. In this structure, nickel ions occupy octahedral positions, forming a layered arrangement with hydroxide ions. Cobalt and zinc ions enter the lattice through isomorphous substitution, partially replacing the nickel ion positions. This doping modification not only maintains the original layered structure but also enhances the material's electrochemical activity through lattice distortion. Appropriate adjustment of the interlayer distance facilitates rapid proton and electron transport, reducing polarization during charging and discharging.

[0060] In terms of electrochemical performance, FC09 exhibits excellent charge-discharge characteristics. Its theoretical specific capacity can reach 289 mAh / g, while the actual discharge specific capacity in practical applications is typically between 230 and 260 mAh / g, depending on the charge-discharge conditions and electrode formulation. The material exhibits a stable charging potential plateau and a distinct discharge voltage plateau, demonstrating good electrochemical reversibility. In the technical solution of this invention, FC09, as the main active material, accounts for 72.30% by mass and is the primary contributor to the electrode capacity.

[0061] FC09 exhibits good compatibility with the functional additives in this invention. The layered structure of bismuth hydroxide synergizes with the layered crystal structure of FC09, and the matching interlayer distances facilitate ion transport. T255 nickel powder not only provides a conductive network but also forms good electrical contact with FC09 particles, reducing interparticle contact resistance. This multi-component synergistic effect allows the electrochemical performance of FC09 to be fully realized.

[0062] As a commercial product, FC09 boasts a stable supply chain and quality assurance system. Its mature manufacturing process results in minimal batch-to-batch performance fluctuations, meeting the demands of large-scale battery production. No complex pretreatment is required before use; it can be directly applied to electrode slurry preparation, simplifying the production process. FC09 exhibits excellent storage stability and can be stored long-term under dry conditions without performance degradation, which is of significant practical importance for industrial production.

[0063] In this embodiment, the high aspect ratio conductive material used in step S1 is spherical chain nickel powder, specifically commercial T255 type nickel powder.

[0064] T255 nickel powder is a functional conductive material with a unique morphology. Its distinctive spherical chain structure is obtained through a specific preparation process. The microstructure of this nickel powder exhibits a chain-like structure formed by multiple interconnected nickel particles. Each chain unit is composed of several spherical or near-spherical nickel particles connected by a sintering neck. This structural feature gives it significant performance advantages compared to traditional spherical nickel powder.

[0065] From a structural perspective, T255 nickel powder has an aspect ratio greater than or equal to 5:1. This high aspect ratio is key to its ability to form an effective three-dimensional conductive network in the electrode. The chain-like structure provides a rapid electron transport channel along its length, while its moderate lateral dimensions ensure good dispersion within the electrode matrix. The nickel powder also exhibits excellent mechanical properties, with a compressive strength exceeding 15 MPa. This strength level provides reliable mechanical support for the electrode, effectively resisting stress changes during charge-discharge cycles.

[0066] The spherical chain morphology of T255 nickel powder is not a simple linear structure, but rather exhibits certain branching and cross-linking characteristics. This quasi-three-dimensional network morphology allows it to form an interconnected conductive framework in electrode materials. When T255 nickel powder is added to electrode materials at a mass percentage of 5% to 8%, the chain structures form a continuous electron transport network through physical contact and overlap. Compared to traditional point-contact conductive networks, this network structure has lower contact resistance and higher conductivity stability.

[0067] In the electrode preparation process, the spherical chain structure of T255 nickel powder also plays an important dispersing role. Its unique morphology can effectively prevent the agglomeration of layered compounds such as bismuth hydroxide particles. During ball milling, the chain-like nickel powder can penetrate between bismuth hydroxide particles under shear force, forming physical isolation and preventing secondary agglomeration of fine particles. Practice shows that when bismuth hydroxide is added alone, the slurry is prone to agglomeration when the amount added increases, while when T255 nickel powder is added simultaneously, the slurry can still maintain a good dispersion state even at a higher amount of bismuth hydroxide.

[0068] T255 nickel powder, as a commercially available product, boasts stable quality and supply guarantees. Its standardized production process ensures batch-to-batch performance consistency. In practical applications, T255 nickel powder requires no additional pretreatment and can be directly used in electrode material preparation, simplifying the production process and reducing production costs.

[0069] By combining T255 nickel powder with layered compounds such as bismuth hydroxide, a dual effect of enhanced conductivity and improved structural stability is achieved. The three-dimensional conductive network constructed by T255 nickel powder provides a high-speed channel for electron transport, while the layered structure of bismuth hydroxide provides functional support for ion transport and volume buffering. The synergistic effect of the two significantly improves the overall performance of the electrode.

[0070] In one embodiment, the binder in step S2 is a thermoplastic polymer or a thermosetting polymer; the thermoplastic polymer includes polytetrafluoroethylene, polyvinylidene fluoride, polyethylene or copolymers thereof; the binder is compounded with the mixture by means of powder mixing, emulsion dispersion or solution impregnation.

[0071] Step S2 specifically includes: The preparation and compounding process of the binder has a significant impact on the final performance of the electrode. In this embodiment, polytetrafluoroethylene (PTFE) is preferably used as the binder, with its mass percentage controlled at 12.00%. The PTFE binder is introduced using a powder mixing method, which ensures the uniform distribution of the binder in the mixture and avoids local enrichment or absence of the binder.

[0072] The binder powder was prepared using spray drying technology. First, a polytetrafluoroethylene (PTFE) emulsion with a solid content of 60% was used as the raw material, and a dispersion of suitable concentration was obtained through dilution and adjustment. Specifically, the PTFE emulsion was mixed with deionized water in a precise ratio, the solid content of the system was adjusted to 12%, and a stable and homogeneous dispersion system was formed through mechanical stirring. This concentration selection ensured both the smooth progress of the spray drying process and the acquisition of a powder product with an ideal particle size distribution.

[0073] Precise control of spray drying process parameters is crucial for obtaining high-quality polytetrafluoroethylene (PTFE) powder. The prepared dispersion is introduced into the spray drying equipment, with the inlet temperature set at 150-200 degrees Celsius and the outlet temperature controlled at 80-100 degrees Celsius. Under these temperature conditions, the dispersion is atomized into tiny droplets by a high-pressure atomizer. These droplets rapidly evaporate moisture in the hot air stream, forming spherical or near-spherical PTFE powder particles. Special care must be taken when selecting temperature parameters to avoid exceeding the decomposition temperature of PTFE while ensuring thorough moisture removal. The powder passing through the drying chamber is collected by a cyclone separator or bag filter, yielding a PTFE powder product with uniform particle size and good flowability.

[0074] The bonding process between the binder and the mixture is completed in a low-speed mixer. The prepared polytetrafluoroethylene (PTFE) powder and the dry mixture obtained in step S1 are added to the low-speed mixer in a predetermined ratio. The mixing speed is controlled at 200 rpm, which ensures thorough mixing of the materials while avoiding structural damage caused by high-speed shearing. The mixing time is set to 10 minutes. During this process, the PTFE powder gradually coats the surface of the dry mixture particles through mechanical action, forming a uniform coating layer.

[0075] The advantage of this powder mixing method lies in its ability to achieve a three-dimensional uniform distribution of the binder within the electrode material. During subsequent heat treatment, the polytetrafluoroethylene powder melts and fibroses, forming a continuous three-dimensional bonding network that firmly binds the active material, conductive material, and additives together. Simultaneously, the dry process avoids the use of solvents, reducing environmental pollution and energy consumption, while improving production efficiency and product quality stability.

[0076] In one embodiment, the molding process in step S3 includes at least one of compression molding, extrusion molding, roll forming, or injection molding; the molding pressure is 5 to 30 MPa, and the density of the molded electrode preform is 60% to 95% of the target theoretical density.

[0077] Molding is a crucial step in transforming powdered composite materials into electrode precursors with specific shapes and densities. In this embodiment, a compression molding process is preferably employed, as this method allows for precise control of key parameters such as electrode thickness, density, and porosity. The compression molding process is conducted at room temperature, avoiding the impact of high temperatures on material properties and simplifying the process flow.

[0078] Step S3 specifically includes: The coating mixture obtained in step S2 is quantitatively loaded into a pre-designed mold. The mold design needs to consider the final dimensional requirements of the electrode and the dimensional shrinkage during the molding process. The mold material is usually high-strength alloy steel, and its inner surface is precision machined and surface treated to ensure that the molded electrode has good surface quality. The loading process needs to ensure that the material is evenly distributed in the mold to avoid uneven electrode performance caused by local density differences.

[0079] The selection of compaction parameters has a decisive impact on electrode performance. The applied pressure is controlled within the range of 10 to 15 MPa, a range that has been optimized. Too low a pressure leads to insufficient contact between particles, poor electrode mechanical strength, and an imperfect conductive network. Too high a pressure may cause the active material particles to break down, damaging the original structure of the material. Furthermore, excessive compaction reduces the porosity of the electrode, hindering electrolyte penetration and ion transport. Within the selected pressure range, good mechanical interlocking and electrical contact can be formed between particles, while retaining a suitable porosity structure.

[0080] The holding time was set to 30 seconds, ensuring uniform pressure distribution and stress relaxation across the entire electrode thickness. During the holding process, the PTFE binder under pressure undergoes plastic deformation, initially forming inter-particle bridges. The spherical chain-like T255 nickel powders overlap under pressure, constructing a preliminary conductive framework. Bismuth hydroxide particles fill the voids between the active material particles; their layered structure aligns under pressure, facilitating the formation of subsequent ion transport channels.

[0081] The density of the formed electrode blank is controlled between 1.8 and 2.2 grams per cubic centimeter, which is equivalent to 70% to 85% of the theoretical density. This density control strategy balances multiple performance indicators of the electrode. Appropriate density ensures the content of active material per unit volume, improving the volumetric energy density of the battery. Simultaneously, the retained porosity provides permeation channels for the electrolyte, ensuring rapid ion transport within the electrode. Reasonable porosity control also provides a buffer for volume changes during charging and discharging, helping to maintain the structural stability of the electrode.

[0082] Quality control during the pressing and molding process is crucial; it is necessary to monitor the thickness uniformity, density distribution, and appearance quality of each batch of products, keeping thickness deviation within ±2% and density deviation within ±3%. The molded electrode blank should have a smooth surface, regular edges, and uniform color, without obvious delamination, cracks, or other defects.

[0083] The advantages of cold pressing are its simplicity, controllable parameters, and good reproducibility. Compared to other methods such as extrusion or injection molding, cold pressing is more suitable for laboratory and pilot-scale production. Furthermore, cold pressing avoids material decomposition or performance degradation that may occur during thermoforming, ensuring the chemical stability and functional integrity of each component. The resulting electrode preform possesses sufficient mechanical strength to withstand subsequent heat treatment and processing, laying the foundation for obtaining high-performance electrodes.

[0084] In one embodiment, the treatment in step S4 includes at least one of heat treatment, radiation treatment, or chemical crosslinking treatment; when heat treatment is used, the treatment temperature is above the glass transition temperature of the adhesive to below its decomposition temperature, and the treatment time is 0.5 to 5 hours.

[0085] Step S4 specifically includes: The pressed electrode blank is treated with heat treatment, and the polytetrafluoroethylene binder is melt-fiberized through precise temperature control.

[0086] The heat treatment process is carried out in a tube furnace, with the electrode blank placed on a quartz boat or ceramic support to ensure uniform heat transfer. The entire heat treatment process is conducted under an argon protective atmosphere, with the argon flow rate controlled within the range of 200 to 500 ml per minute. This inert atmosphere prevents oxidation of the material under high-temperature conditions, especially protecting T255 nickel powder and other metal components from oxidation and maintaining their excellent electrical conductivity.

[0087] The heating process employs a programmed temperature control method, raising the temperature from room temperature to 350 degrees Celsius at a rate of 5 degrees Celsius per minute. This heating rate was chosen based on several considerations. Excessive heating could lead to a large internal temperature gradient in the electrode, generating thermal stress and causing cracking or deformation. Insufficient heating would prolong the production cycle and reduce production efficiency. The selected heating rate ensures uniform temperature throughout the electrode, preventing structural damage caused by thermal shock.

[0088] Polytetrafluoroethylene (PTFE) has a glass transition temperature of approximately 127°C, a melting point of 327°C, and a decomposition temperature exceeding 400°C. Choosing 350°C as the processing temperature ensures that it is above PTFE's melting point, allowing for complete melting and fibrous transformation. Simultaneously, this temperature is below its decomposition temperature, preventing thermal decomposition of PTFE and preserving its chemical structure and adhesive properties.

[0089] During the isothermal stage at 350 degrees Celsius, the holding time was 2 hours. Under these temperature conditions, polytetrafluoroethylene (PTFE) underwent a complex physicochemical transformation process. First, the PTFE particles melted, forming a viscous melt. Subsequently, driven by surface tension and capillary forces, the molten PTFE flowed and spread between the particles, forming a continuous thin film structure. More importantly, under high temperature and stress, the PTFE molecular chains oriented and stretched, forming a fibrous structure. These fibers intertwined, constructing a three-dimensional network structure that firmly binds the active material particles, conductive agents, and additives together.

[0090] The fibrous formation of polytetrafluoroethylene (PTFE) not only provides mechanical bonding, but the resulting three-dimensional network also possesses a degree of elasticity, enabling it to adapt to electrode volume changes during charge and discharge and alleviate stress concentration. Simultaneously, the fibrous PTFE maintains its excellent chemical and electrochemical stability, and will not undergo degradation or side reactions in the battery operating environment.

[0091] Natural cooling is employed, allowing the electrode sheets to slowly cool to room temperature within the furnace. This slow cooling process helps eliminate thermal stress and prevents electrode warping or cracking caused by rapid cooling. During the cooling process, the PTFE fiber network structure is fixed and strengthened, ultimately forming a stable three-dimensional bonding system.

[0092] The treated electrode should possess good mechanical strength to withstand subsequent rolling and cutting processes. The electrode's flexibility is improved, allowing it to bend to a certain extent without breaking. Electrochemical testing shows that the electrode, after appropriate heat treatment, exhibits lower internal resistance and better cycle stability, fully demonstrating the effectiveness of the three-dimensional bonded network formation.

[0093] The advantage of this heat treatment process lies in its ability to achieve effective distribution and networking of the binder without the use of solvents, aligning with the development direction of green manufacturing. Simultaneously, precise control of heat treatment parameters ensures the consistency and reproducibility of product quality, providing a reliable technical guarantee for the large-scale production of electrodes.

[0094] In one embodiment, step S4 is followed by: Step S5: Post-process the secondary battery electrode, including adjusting the thickness of the secondary battery electrode and then combining it with the current collector to obtain a secondary battery composite electrode.

[0095] Step S5 specifically includes: adjusting the secondary battery electrode to a predetermined thickness range through a rolling process; performing a composite compaction process on the thickness-adjusted secondary battery electrode and the current collector to form an integrated structure, thereby obtaining a secondary battery composite electrode; cutting the secondary battery composite electrode and connecting conductive leads to obtain the secondary battery electrode; wherein, the current collector is a metal substrate with a three-dimensional porous structure or a two-dimensional mesh structure. The current collector includes foamed nickel-plated stainless steel mesh, inclined stainless steel mesh, inclined nickel mesh, perforated nickel-plated stainless steel strip, perforated stainless steel strip, and perforated nickel strip.

[0096] Further, the predetermined thickness ranges from 0.3 to 0.8 mm; the current collector is selected from at least one of foamed metal, metal mesh, perforated metal strip, or metal-plated composite substrate; the conductive lead-out end is connected to the electrode by ultrasonic welding, laser welding, or conductive adhesive bonding, and the conductive lead-out end is an electrode tab.

[0097] The present invention also proposes an aqueous secondary battery, wherein the aqueous secondary battery includes the electrode prepared by the above method; the aqueous secondary battery is an alkaline secondary battery, a neutral aqueous battery, or a weakly acidic aqueous battery; the alkaline secondary battery includes a zinc-nickel battery, a zinc-manganese battery, a nickel-metal hydride battery, or a nickel-cadmium battery.

[0098] The embodiments of the present invention will be described in detail below with reference to specific examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0099] In the technical solution of this invention, the layered compound is preferably bismuth hydroxide. Bismuth hydroxide has a typical two-dimensional layered crystal structure, in which hydroxide ions and bismuth ions form a two-dimensional layered arrangement through coordination bonds, and the layers are bonded by hydrogen bonds or van der Waals forces. This unique structure endows bismuth hydroxide with multiple functional properties. First, the ordered interlayer channels provide a low-barrier transport path for zinc ions, which can significantly improve ion transport efficiency compared to the traditional disordered diffusion path. Second, the tunable interlayer spacing allows it to buffer the volume change of the electrode through interlayer expansion and contraction during charging and discharging. Experimental data show that after adding bismuth hydroxide, the expansion coefficient of the positive electrode decreases from 0.35 to 0.23 to 0.28, a reduction of 20% to 34%. Third, the interlayer water molecules play a stabilizing role in the nickel ion redox process through the dynamic adjustment of the hydrogen bond network, effectively suppressing structural collapse during the phase transition process.

[0100] In this invention, the preferred high aspect ratio conductive material is spherical chain-like nickel powder T255. T255 nickel powder is a functional conductive material with a unique morphology; its distinctive spherical chain structure is obtained through a specific preparation process. The microstructure of this nickel powder exhibits a chain-like structure formed by multiple interconnected nickel particles. Each chain unit is composed of several spherical or near-spherical nickel particles connected by a sintering neck. The aspect ratio of T255 nickel powder is greater than or equal to 5:1, and this high aspect ratio is key to its ability to form an effective three-dimensional conductive network in the electrode. This nickel powder also possesses excellent mechanical properties, with a compressive strength exceeding 15 MPa, a strength level that provides reliable mechanical support for the electrode.

[0101] The electrode active material used is commercially available FC09, a specially modified nickel-based compound. FC09 is a zinc-added spherical nickel hydroxide material with a precisely controlled chemical composition, where the mass ratio of nickel, cobalt, and zinc is 54:4:4. This specific elemental ratio provides good structural stability while maintaining high electrochemical activity. FC09 has a β-type nickel hydroxide crystal structure with hexagonal layered characteristics. As a commercial product, FC09 has stable supply channels and a quality assurance system.

[0102] The embodiments of the present invention will be described in detail below with reference to specific examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0103] Example 1 A zinc-nickel battery dry cathode composition, by mass percentage, comprises 72.30% FC09 nickel-based active material, 7.30% T255 spherical chain nickel powder, 6.60% multi-walled carbon nanotubes, 1.80% bismuth hydroxide, and 12.00% polytetrafluoroethylene.

[0104] Methods for preparing secondary battery electrodes: Dry material premixing: FC09 nickel-based active material, T255 nickel powder, multi-walled carbon nanotubes, bismuth hydroxide and 0.1% isopropanol dispersant were placed in a planetary ball mill. Under argon protection, zirconia balls were used as the ball milling medium, the ball-to-material ratio was 12:1, the rotation speed was 500 rpm, and the ball milling was carried out for 2 hours to obtain a mixed dry material with a particle size D50 < 50 μm.

[0105] Adhesive coating: The 60% solids content polytetrafluoroethylene emulsion was diluted to 12% solids content and then powdered by spray drying at an inlet temperature of 175℃ and an outlet temperature of 90℃. The resulting PTFE powder was then mixed with the dry mixture in a low-speed mixer at 200 rpm for 10 minutes.

[0106] Compression molding: The composite material is loaded into a 120mm×90mm mold, cold-pressed under 12 MPa pressure for 30 seconds, yielding a density of 2.0 g / cm³. 3 The electrode blank.

[0107] Heat treatment: The electrode blank is placed in a tube furnace under argon protection (flow rate 300 mL / min), heated to 350℃ at 5℃ / min, held at the temperature for 2 hours, and then cooled naturally.

[0108] Post-processing: The thickness is adjusted to 0.45-0.50mm by rolling, combined with nickel foam current collector, cut into 100mm×70mm specifications, and nickel-plated tabs are ultrasonically welded to obtain a dry cathode with a theoretical capacity of 3000mAh.

[0109] Example 2 The composition, by mass percentage, comprises 68.40% FC09 nickel-based active material, 8.00% T255 spherical chain nickel powder, 6.60% multi-walled carbon nanotubes, 3.00% bismuth hydroxide, and 14.00% polytetrafluoroethylene. The preparation method is the same as in Example 1.

[0110] Example 3 The composition, by mass percentage, comprises 75.40% FC09 nickel-based active material, 5.00% T255 spherical chain nickel powder, 6.60% multi-walled carbon nanotubes, 1.00% bismuth hydroxide, and 12.00% polytetrafluoroethylene. The preparation method is the same as in Example 1.

[0111] Comparative Example 1 The composition, by mass percentage, comprises 72.30% FC09 nickel-based active material, 7.30% T255 spherical chain nickel powder, 6.60% multi-walled carbon nanotubes, and 13.80% polytetrafluoroethylene. Bismuth hydroxide is not added, and the preparation method is the same as in Example 1.

[0112] Comparative Example 2 The composition, by mass percentage, comprises 79.60% FC09 nickel-based active material, 6.60% multi-walled carbon nanotubes, 1.80% bismuth hydroxide, and 12.00% polytetrafluoroethylene. T255 nickel powder is not added, and the preparation method is the same as in Example 1.

[0113] Comparative Example 3 The composition, by mass percentage, consists of 81.40% FC09 nickel-based active material, 6.60% multi-walled carbon nanotubes, and 12.00% polytetrafluoroethylene. T255 nickel powder and bismuth hydroxide are not added; the preparation method is the same as in Example 1.

[0114] Performance Testing and Analysis The positive electrodes prepared in each embodiment and comparative example were assembled with zinc oxide negative electrodes and 6M potassium hydroxide electrolyte into pouch cells, and charge-discharge tests were conducted at a voltage window of 1.4-1.95V and a rate of 0.5C. The test results are summarized in Table 1.

[0115] Table 1 Electrochemical performance test results ; Table 2. Test results of positive electrode expansion coefficient after the first charge and discharge cycle. ; Reference Figure 1 As shown, the dry-process positive electrode prepared by this invention exhibits a regular rectangular appearance, with a coating area size of 10cm × 7cm. The surface is uniform and smooth, without obvious defects, demonstrating good molding quality. The electrode sheet possesses moderate flexibility, meeting the process requirements for battery assembly.

[0116] Figure 2 The comparison curves of battery cycle performance between Examples 1-3 and Comparative Examples 1-3 are clearly shown. It is evident from the graph that the cycle curve of Example 1 remains stable throughout 100 cycles, exhibiting slow capacity decay and demonstrating excellent cycle stability. In contrast, Comparative Example 1 shows significant capacity decay within the first 50 cycles, Comparative Example 2 shows acceptable initial performance but accelerated capacity decay later, while Comparative Example 3 exhibits the worst cycle stability. This result fully demonstrates the crucial role of the synergistic effect of bismuth hydroxide and T255 nickel powder in improving battery cycle performance.

[0117] Based on the data analysis in Table 1, the cathode utilization rates of Examples 1-3 reached 80.15%-81.20%, an increase of approximately 20 percentage points compared to Comparative Example 3, indicating that the bifunctional additive significantly improved the electrochemical activity of the active material. Regarding the first-cycle coulombic efficiency, all examples exceeded 97%, close to the theoretical value, while the highest of the comparative examples was only 82.13%, demonstrating that the synergistic additive effectively suppressed the occurrence of side reactions. The most significant improvement was reflected in cycle stability; after 100 cycles, the capacity retention rate of the examples remained above 90%, while that of Comparative Example 1 was only 56.21%, and that of Comparative Example 3 was 68.37%, fully verifying the effectiveness of the technical solution of this invention.

[0118] The expansion coefficient test results in Table 2 further reveal the unique mechanism of action of bismuth hydroxide. Using 5% T255 nickel powder as a baseline, as the bismuth hydroxide addition increased from 1% to 3%, the expansion coefficient gradually decreased from 0.35 to 0.23, a reduction of 34%. This phenomenon confirms the important function of the layered structure of bismuth hydroxide in buffering volume changes during charge and discharge processes. The flexible structure formed by interlayer water molecules through hydrogen bonding effectively adapts to the lattice changes of nickel-based materials during redox processes, reducing the accumulation of mechanical stress.

[0119] Comparative Example 1, lacking bismuth hydroxide, although possessing the conductive network provided by T255 nickel powder, could not effectively buffer volume changes, leading to a sharp deterioration in cycling performance. Comparative Example 2, lacking T255 nickel powder, lost the supporting role of the three-dimensional conductive framework, making the electrode prone to pulverization during cycling, with an active material utilization rate of only 65.67%. Comparative Example 3, lacking both functional additives, exhibited the worst performance in all aspects, fully demonstrating the irreplaceable synergistic effect of the two components.

[0120] Comprehensive experimental results demonstrate that this invention, through the rational design of the synergistic mechanism between bismuth hydroxide and T255 nickel powder, successfully solves the technical challenges in stability, cycle life, and kinetic performance of zinc-nickel battery cathodes. The layered structure of bismuth hydroxide improves electrode performance from the perspectives of ion transport and volume buffering, while the three-dimensional network of T255 nickel powder provides enhancement from the perspectives of electronic conductivity and mechanical support. The two complement each other, achieving a comprehensive improvement in the overall electrode performance. This technical solution is simple to implement and yields significant results, providing reliable technical support for the industrial application of high-performance zinc-nickel batteries.

[0121] Unless otherwise specified, the raw materials and equipment used in this invention are commonly used in the field; the methods used in this invention are conventional methods in the field. Unless otherwise specified, the meanings of the terms in this specification are the same as those generally understood by those skilled in the art, but in case of conflict, the definitions in this specification shall prevail.

[0122] The foregoing examples are merely illustrative, used to explain some features of the method described in this invention. The appended claims are intended to claim the broadest possible scope, and the embodiments presented herein are merely illustrative of selected implementations based on combinations of all possible embodiments. Therefore, the applicant intends that the appended claims are not limited by the selection of examples illustrating the features of the invention. Some numerical ranges used in the claims also include sub-ranges within them, and variations within these ranges should also be interpreted as being covered by the appended claims where possible.

Claims

1. A method for preparing a secondary battery electrode, characterized in that, Includes the following steps: Step S1: Mix the electrode active material, the conductive material with a high aspect ratio structure, the conductive agent, and the layered structure compound to obtain a mixture; the layered structure compound has an interlayer structure that can provide ion transport channels and buffer volume changes during charging and discharging; the aspect ratio of the conductive material with a high aspect ratio structure is greater than 3:1; Step S2: Combine the binder with the mixture to distribute the binder throughout the mixture, thereby obtaining a composite material; Step S3: The composite material is molded to obtain an electrode preform; Step S4: Process the electrode blank to form a three-dimensional bonding network with the binder, thereby obtaining a secondary battery electrode; The layered compound and the high aspect ratio conductive material work synergistically to improve the electrochemical performance of the electrode in terms of ion transport, volume stability and electronic conductivity, respectively.

2. The method according to claim 1, characterized in that, The layered compound is selected from at least one of metal hydroxides, layered double hydroxides, layered metal oxides, or layered metal sulfides; the layered compound is preferably a compound having a two-dimensional layered crystal structure, wherein the layers are bonded by hydrogen bonds or van der Waals forces.

3. The method according to claim 1 or 2, characterized in that, The layered compound is at least one of bismuth hydroxide, magnesium hydroxide, aluminum hydroxide, cobalt hydroxide, manganese hydroxide, or a complex hydroxide thereof; the layered compound accounts for 0.5% to 10% of the mass percentage of the compound in the mixture.

4. The method according to claim 1, characterized in that, The conductive material with a high aspect ratio structure is at least one of metal powder, carbon fiber, carbon nanotube, metal nanowire or conductive polymer fiber; the conductive material with a high aspect ratio structure is preferably a material with a chain-like, fibrous or dendritic morphology, which can form a three-dimensional conductive network in the electrode.

5. The method according to claim 4, characterized in that, The metal powder is nickel powder, cobalt powder, copper powder, silver powder or its alloy powder; the metal powder has a spherical chain-like, dendritic or fibrous structure, with an aspect ratio of 5:1 to 20:1, and a mass percentage of 3% to 15% in the mixture.

6. The method according to claim 1, characterized in that, The mixing process in step S1 is carried out under a protective atmosphere or vacuum, and is performed by at least one of mechanical mixing, ball milling, high-energy ball milling or air jet milling. A dispersing agent may be added during the mixing process, and the amount of the dispersing agent added is 0.05% to 1% of the total mass of the mixture.

7. The method according to claim 1, characterized in that, The binder in step S2 is a thermoplastic polymer or a thermosetting polymer; the thermoplastic polymer includes polytetrafluoroethylene, polyvinylidene fluoride, polyethylene or copolymers thereof; the binder is compounded with the mixture by means of powder mixing, emulsion dispersion or solution impregnation.

8. The method according to claim 1, characterized in that, The molding process in step S3 includes at least one of compression molding, extrusion molding, roll forming or injection molding; the molding pressure is 5 to 30 MPa, and the density of the formed electrode preform is 60% to 95% of the target theoretical density.

9. The method according to claim 1, characterized in that, The treatment in step S4 includes at least one of heat treatment, radiation treatment, or chemical crosslinking treatment; when heat treatment is used, the treatment temperature is above the glass transition temperature of the adhesive to below the decomposition temperature, and the treatment time is 0.5 to 5 hours.

10. An aqueous secondary battery, characterized in that, The method includes electrodes prepared according to any one of claims 1 to 9; the aqueous secondary battery is an alkaline secondary battery, a neutral aqueous battery, or a weakly acidic aqueous battery; the alkaline secondary battery includes a zinc-nickel battery, a zinc-manganese battery, a nickel-metal hydride battery, or a nickel-cadmium battery.

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