Battery cell, method for producing the same, battery device, electric device, and energy storage device

Abstract

The application provides a battery monomer, a preparation method thereof, a battery device, a power utilization device and an energy storage device. A positive electrode binder of the battery monomer comprises a continuous matrix phase material and a dispersed functional domain phase material; the continuous matrix phase material comprises an organic polymer; the dispersed functional domain phase material comprises organic-inorganic hybrid porous particles, which comprise a porous inorganic oxide and an N-containing heterocyclic organic layer, and the N-containing heterocyclic organic layer is grafted on the surface of the porous inorganic oxide. The application introduces a multifunctional binder with a dispersed porous weak alkaline functional domain in the binder system, realizes partial adsorption and neutralization of acidic by-products generated in the electrode, partial adsorption and buffering of gaseous by-products, mechanical adaptation to volume change and micro-cracks of the positive electrode particles, improvement of electrolyte infiltration and ion transmission, and can improve the cycle stability and structural integrity of a high-nickel battery system under high voltage and high temperature.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more specifically, to a battery cell and its preparation method, a battery device, an electrical device, and an energy storage device. Background Technology

[0002] Binders are a crucial component of the positive electrode coating in lithium-ion batteries. Their primary function is to bond active material particles and conductive agents together and fix them on the current collector surface, forming a stable electrode structure. Traditional positive electrode binders mainly include polyvinylidene fluoride and its copolymers, polyimide, and aromatic polyethers. The design focus of these binders is to provide sufficient bond strength, good electrochemical stability, especially oxidation resistance, and appropriate flexibility to accommodate the volume changes of the electrode during charging and discharging.

[0003] High-nickel ternary cathode materials typically refer to nickel-cobalt-manganese or nickel-cobalt-aluminum ternary materials where the molar percentage of Ni in the total transition metal is greater than 80%. High-nickel ternary cathode materials have become an important development direction for power batteries and energy storage batteries due to their high specific capacity and high energy density. However, high-nickel materials face significant technical challenges in practical applications. First, during high-voltage charging, especially above 4.3V, complex side reactions occur on the cathode surface, including the release of lattice oxygen, changes in the valence state of transition metals and partial dissolution, as well as the oxidative decomposition of the electrolyte. These reactions lead to the generation of gases such as carbon dioxide and carbon monoxide, and the formation of acidic substances such as hydrogen fluoride. The accumulation of gases can cause cell expansion and bulging, while acidic substances such as hydrogen fluoride can exacerbate corrosion of the cathode material surface and dissolution of transition metals, creating a vicious cycle.

[0004] Secondly, high-nickel materials undergo significant changes in lattice parameters and volume during charging and discharging, making them prone to microcracks within secondary particles. These microcracks expose new surfaces, increasing the contact area with the electrolyte and further exacerbating side reactions. Simultaneously, the propagation of microcracks and particle breakage can lead to contact failure with binders and conductive agents, causing electrochemical isolation of some active materials and resulting in capacity loss. While traditional binders such as polyvinylidene fluoride (PVDF) possess good chemical stability and certain mechanical strength, their design primarily focuses on providing basic bonding functions, lacking functional designs specifically tailored to the problems of high-nickel systems. Summary of the Invention

[0005] The main objective of this invention is to provide a battery cell and its preparation method, battery device, power consumption device, and energy storage device, in order to solve the problem that the interface stability and structural stability of the high-nickel cathode system in lithium batteries under high voltage conditions are poor, resulting in poor cycle life, high-temperature storage performance, and safety of the battery.

[0006] To achieve the above objectives, according to one aspect of the present invention, a battery cell is provided, comprising a positive electrode, a negative electrode, a separator, and an electrolyte. The positive electrode comprises a positive current collector and a positive electrode film layer disposed on at least one side surface of the positive current collector. The positive electrode film layer comprises a positive active material, a conductive agent, and a binder. The binder comprises a continuous matrix phase material and a dispersed functional domain phase material. The continuous matrix phase material comprises an organic polymer. The dispersed functional domain phase material comprises organic-inorganic hybrid porous particles, wherein the organic-inorganic hybrid porous particles comprise a porous inorganic oxide and an N-heterocyclic organic layer, and the N-heterocyclic organic layer is grafted onto the surface of the porous inorganic oxide.

[0007] Furthermore, the porous inorganic oxides include porous silica and / or porous alumina; and / or the materials containing an N-heterocyclic organic layer include one or more of the following: pyridine and its derivatives, pyrazine, triazine and its derivatives, imidazole and its derivatives, benzimidazole, 1,2,4-triazole.

[0008] Furthermore, the porous inorganic oxide has a pore size of 3~15nm, a porosity of 30~70%, and a particle size Dv50 of 50nm~1μm.

[0009] Furthermore, the thickness of the N-heterocyclic organic layer is 1~3 nm.

[0010] Furthermore, the N-heterocyclic organic layer contains electron-withdrawing substituents on its N-heterocyclic organic layer; wherein the electron-withdrawing substituents include one or more of trifluoromethyl, fluorine, and cyano groups; and / or the functional group density of the electron-withdrawing substituents is: 0.5~3 mmol of electron-withdrawing substituents per 1g of dispersed functional domain phase material.

[0011] Furthermore, the dispersed functional domain phase material accounts for 10-30% of the weight of the binder; and / or the continuous matrix phase material accounts for 70-90% of the weight of the binder.

[0012] Furthermore, the organic polymer includes one or more of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyimide, polyethersulfone, and polyetheretherketone.

[0013] Furthermore, the positive electrode active material includes NCM material and / or NCA material; and / or the positive electrode active material includes one or more of high-nickel positive electrode materials, ultra-high-nickel positive electrode materials and single-crystal high-nickel materials, wherein the molar percentage of Ni in the total transition metal in the high-nickel positive electrode material is 80~85%, and the molar percentage of Ni in the total transition metal in the ultra-high-nickel positive electrode material is greater than 85% and less than or equal to 95%.

[0014] Furthermore, when the positive electrode active material includes a high-nickel positive electrode material, the dispersed functional domain phase material accounts for 15-25% of the weight of the binder, and the pore size of the dispersed functional domain phase material is 5-10 nm. Optionally, the N-heterocyclic organic layer contains electron-withdrawing substituents, and the functional group density of the electron-withdrawing substituents is: 1-2 mmol of electron-withdrawing substituents per 1 g of dispersed functional domain phase material. When the positive electrode active material includes an ultra-high-nickel positive electrode material, the dispersed functional domain phase material accounts for 20-30% of the weight of the binder, and the material containing the N-heterocyclic organic layer includes imidazole and its derivatives. When the positive electrode active material includes a single-crystal high-nickel material, the dispersed functional domain phase material accounts for 10-20% of the weight of the binder.

[0015] Furthermore, the binder accounts for 3-8% of the weight of the positive electrode film; and / or the dispersed functional domain phase material accounts for 0.3-2.4% of the weight of the positive electrode film; and / or the weight ratio of the positive electrode active material, conductive agent and binder in the positive electrode film is (90-96):(2-5):(3-8).

[0016] Further, the method includes the following steps: Step S1, mixing a porous inorganic oxide, an N-heterocyclic silane coupling agent, and a first solvent, and performing a hydrolysis-condensation reaction to graft an N-heterocyclic organic layer onto the surface of the porous inorganic oxide, and drying to obtain a dispersed functional domain phase material; Step S2, mixing an organic polymer and a second solvent to obtain an organic polymer solution; mixing the organic polymer solution with the dispersed functional domain phase material and an optional dispersant, and dispersing to obtain a solution containing a binder; Step S3, mixing a positive electrode active material, a conductive agent, and a binder-containing solution to obtain a positive electrode slurry; coating the positive electrode slurry onto at least one side of the positive electrode current collector, drying to form a positive electrode film layer, and rolling to obtain a positive electrode sheet; Step S4, assembling the positive electrode sheet, negative electrode sheet, separator, electrolyte, casing, and top cover to obtain a battery cell.

[0017] Further, in step S1, the N-heterocyclic silane coupling agent includes one or more of (3-pyridylpropyl)trimethoxysilane, triazine silane coupling agent, N-(3-triethoxysilylpropyl)imidazolium, 4-fluoro-1-[3-(triethoxysilyl)propyl]imidazolium, 5-cyano-1-[3-(trimethoxysilyl)propyl]benzimidazole, and 2-(trimethoxysilylethyl)pyridine; wherein, the raw materials for the triazine silane coupling agent include 3-aminopropyltriethoxysilane and cyanuric chloride; optionally, the N-heterocyclic silane coupling agent further has an electron-withdrawing substituent on its N-heterocyclic ring, the electron-withdrawing substituent including trifluoromethyl, fluorine atom, and cyano group. One or more of the following: and / or, in step S1, the weight ratio of porous inorganic oxide to N-heterocyclic silane coupling agent is 1:(0.10~0.50); ​​and / or, in step S1, the hydrolysis-condensation reaction temperature is 60~80℃ and the time is 4~8h; and / or, in step S2, the dispersant includes one or more of polyvinylpyrrolidone, polyethylene glycol and sodium dodecylbenzenesulfonate; and / or, in step S2, the weight ratio of organic polymer to dispersion functional domain phase material is (70~90):(10~30); and / or, in step S2, the weight ratio of dispersant to dispersion functional domain phase material is (0.05~0.2):1.

[0018] According to another aspect of the present invention, a battery device is provided, comprising the battery cell described above, and the battery device includes one or more of the following: battery module, battery pack, and energy storage battery.

[0019] According to another aspect of the present invention, an electrical device is provided, which includes the battery device described above, the battery device being used to provide electrical energy.

[0020] According to another aspect of the present invention, an energy storage device is provided, which includes the battery device described above, the battery device being used to store electrical energy.

[0021] By applying the technical solution of this invention, a multifunctional binder with dispersed porous weakly basic functional domains is introduced into the binder system. While maintaining the bonding strength and electrochemical stability, it can achieve partial adsorption and neutralization of acidic byproducts such as hydrogen fluoride generated inside the electrode, partial adsorption and buffering of gaseous byproducts such as carbon dioxide, mechanical adaptation to changes in the volume of positive electrode particles and microcracks, and improvement of electrolyte wetting and ion transport. This can significantly improve the cycle stability and structural integrity of high-nickel battery systems under high voltage and high temperature conditions. Attached Figure Description

[0022] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0023] Figure 1 A process flow diagram for the fabrication of a battery cell according to an embodiment of the present invention is shown. Detailed Implementation

[0024] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0025] As described in the background section of this invention, existing technologies suffer from poor interface and structural stability of the high-nickel cathode system in lithium batteries under high voltage conditions, resulting in poor cycle life, high-temperature storage performance, and safety of the batteries.

[0026] Existing technical solutions mainly focus on two aspects: surface coating of cathode materials and optimization of electrolyte formulations. Surface coatings, such as inorganic layers like alumina and aluminum phosphate, can effectively suppress side reactions on the cathode surface and reduce the generation of gases and acidic substances. Electrolyte additives, such as lithium fluoride phosphide and vinyl sulfate, can regulate the oxidative stability of the electrolyte and the interfacial reaction pathway to some extent. However, these methods mainly focus on source control and bulk phase regulation, and have limited ability to handle gases and acidic byproducts already generated inside the electrode. Especially during long-term cycling and high-temperature storage, even effective surface coating and electrolyte optimization cannot completely prevent the accumulation of small amounts of byproducts. These residual gases and acidic substances gradually accumulate in the pores inside the electrode, eventually leading to structural degradation and performance decline.

[0027] The high specific capacity of high-nickel materials stems from nickel's high redox potential and multi-electron transfer capability, but it also presents significant technical challenges. When charged to high voltages, nickel ions on the surface of high-nickel materials are in a high valence state, making it easier for lattice oxygen to be released, leading to surface structural phase transitions and the dissolution of transition metals. Simultaneously, high potentials trigger the oxidative decomposition of the electrolyte, particularly carbonate solvents, producing gases such as carbon dioxide and carbon monoxide, as well as various organic and inorganic byproducts. Furthermore, lithium hexafluorophosphate in the electrolyte decomposes under high temperature and high voltage to produce phosphorus pentafluoride and hydrogen fluoride. Hydrogen fluoride, as a strong acid, further corrodes the cathode material surface, dissolving transition metal ions.

[0028] Another characteristic of high-nickel materials is the significant change in lattice parameters during charging and discharging. Nickel ions have different ionic radii at different valence states, and the redox reactions during charging and discharging lead to lattice expansion and contraction. For polycrystalline secondary particles, due to the different orientations of the primary particles, the anisotropic volume changes during charging and discharging generate stress at the interparticle interfaces, which accumulates to a certain extent and forms microcracks. The formation of microcracks not only increases the contact area with the electrolyte, exacerbating side reactions, but also causes some particles to separate from the conductive and binder networks, resulting in capacity loss and increased impedance.

[0029] Traditional binders have inherent limitations in addressing these challenges. While materials such as polyvinylidene fluoride (PVDF) possess good chemical stability, their primary function is mechanical bonding, lacking the ability to actively adsorb, neutralize, or buffer gases and acidic byproducts generated within the electrode. Once these byproducts accumulate to a certain extent in the pores within the electrode, they can lead to problems such as localized stress concentration, bonding interface failure, and even cell bulging. Furthermore, the dense structure of traditional binders also has limited capacity to accommodate particle volume changes and microcracks.

[0030] In recent years, technological innovations to address the stability issues of high-nickel cathodes have primarily focused on two directions. First, surface coating of the cathode material involves coating the cathode particles with inorganic layers such as alumina, zirconium oxide, aluminum phosphate, and lithium fluoride, or ionic conductor layers such as LiNbO3 and Li3PO4. This physically isolates the cathode material from direct contact with the electrolyte, reducing surface side reactions and transition metal dissolution. Second, electrolyte formulation optimization involves adding oxidation-resistant solvents such as fluorocarbonates and vinyl sulfate, or cathode film-forming additives such as lithium fluoride phosphide and trimethyl borate, to improve the oxidative stability of the electrolyte or form a protective interfacial film on the cathode surface. While these technologies have achieved significant results, they mainly focus on source control and bulk phase regulation, with relatively less attention paid to the regulation of the internal electrode structure and local environment.

[0031] Functionalization of binders is a relatively new field. Some studies have attempted to introduce specific functional groups or fillers into binders to achieve additional functions, such as conductive binders to improve electron conduction, ion-conducting binders to improve lithium-ion transport, and self-healing binders to cope with volume changes. However, there are still few binder solutions that systematically address the multiple problems unique to high-nickel cathodes, such as gas generation, acid accumulation, and microcrack propagation.

[0032] The main types of binders used in high-nickel ternary cathodes fall into several typical technical categories. Traditional PVDF (polyvinylidene fluoride) binder is the most widely used cathode binder. As a semi-crystalline polymer, it possesses excellent chemical stability and oxidation resistance, remaining stable even at high voltages above 4.5V. PVDF is prepared by dissolving it in solvents such as N-methylpyrrolidone to form a slurry, which is then mixed with the cathode active material and conductive agent and coated onto an aluminum foil current collector. After drying, it forms an electrode coating. The bonding mechanism of PVDF is mainly physical adsorption and mechanical coating; its long-chain molecules form connecting bridges between particles, providing adhesion. PVDF's advantages lie in its mature process, moderate cost, and wide electrochemical window. However, its function is limited, primarily providing mechanical bonding, and it lacks the ability to actively treat byproducts generated at high voltages on the cathode.

[0033] High-performance polymers such as polyimide binders and aromatic polyether binders have seen some application in high-nickel cathodes in recent years. These binders typically possess higher glass transition temperatures, better high-temperature stability, and superior mechanical properties. Polyimides contain an imide ring structure, exhibiting strong molecular chain rigidity and excellent heat resistance and electrochemical stability. Aromatic polyethers, such as polyethersulfone, combine rigid aromatic rings with flexible ether bonds, maintaining high stability while also possessing a degree of flexibility. The design philosophy of these high-performance binders is to enhance the stability of the binder itself to cope with the harsh environment of high-nickel cathodes, but they also lack specific functional designs for byproduct handling and structural buffering.

[0034] Conductive binders are traditional binders with the addition or grafting of conductive components such as polyaniline, polypyrrole, and carbon nanotubes, which endow the binder with electronic conductivity to improve the electronic conduction network of the electrode. These binders are effective in improving rate performance and reducing polarization, but they mainly focus on electronic conduction and do not provide solutions for the gas generation and acid corrosion problems of high-nickel cathodes.

[0035] Composite binders containing organic / inorganic fillers improve the mechanical properties, thermal stability, or electrochemical stability of the binder by adding inorganic fillers such as nano-alumina, silica, and zirconium oxide. Inorganic fillers can act as reinforcing phases, increasing the modulus and strength of the binder, and may also improve the interfacial properties with the electrolyte. However, conventional inorganic filler additions primarily focus on mechanical reinforcement; the fillers themselves are usually dense inorganic particles and lack the adsorption and buffering capabilities for gases and acidic substances.

[0036] In addition, existing mainstream technologies for improving the stability of high-nickel cathodes include cathode material surface coating and electrolyte formulation optimization. Surface coating forms a protective layer on the surface of cathode particles, physically isolating the active material from the electrolyte and reducing surface side reactions. Commonly used coating materials include inorganic materials such as alumina, zirconium oxide, aluminum phosphate, and lithium fluoride, as well as carbon coating. The coating layer provides physical shielding, and some coating materials, such as aluminum phosphate, can also capture acidic substances such as hydrogen fluoride. Electrolyte formulation optimization involves selecting more stable solvents such as fluorocarbonates, or adding cathode protective additives such as vinyl sulfate, lithium fluoride phosphate, and borate esters to form a protective interfacial film on the cathode surface or improve the electrolyte's antioxidant capacity.

[0037] These existing technologies each have their own mechanisms of action and advantages, but they also share common limitations: they mainly act on the particle surface or the electrolytic liquid phase, and lack direct and effective means to address the accumulation of byproducts in the microenvironment inside the electrode, especially in the binder network and pore structure. When the positive electrode inevitably generates small amounts of gas and acidic substances during long-term cycling or high-temperature storage, these byproducts gradually accumulate in the pores inside the electrode. Traditional binders are unable to handle these byproducts, ultimately leading to increased local stress, bonding failure, and even cell bulging.

[0038] In summary, while existing technologies have made some progress in addressing the interface and structural stability issues of high-nickel ternary cathode materials, the following systemic problems and technical limitations still exist.

[0039] First, existing binders lack the ability to actively handle byproducts within the electrode. High-nickel cathodes generate gases such as carbon dioxide and carbon monoxide, as well as acidic substances like hydrogen fluoride, during high-voltage charging and high-temperature storage. Even with effective surface coating and electrolyte optimization, it is difficult to completely avoid the generation of these byproducts, especially during long-term use. Traditional binders such as PVDF and polyimide, while stable themselves, lack the ability to adsorb, neutralize, or buffer gases and acidic substances accumulated in the pores within the electrode. Gas accumulation leads to increased internal electrode pressure, causing separation at the interface between the active material and the binder, potentially resulting in cell bulging. The accumulation of acidic substances like hydrogen fluoride within the electrode continuously corrodes the cathode material surface, promoting transition metal dissolution, creating a vicious cycle, and accelerating capacity decay and impedance increase.

[0040] Secondly, existing binders are insufficiently adaptable to microcracks and volume changes in cathode particles. High-nickel materials undergo significant changes in lattice parameters and volume during charge and discharge, making them prone to microcracks within secondary particles. While traditional dense binders can provide some bonding strength, their rigid structure lacks an effective buffering and adaptation mechanism for localized particle deformation and crack propagation. When microcracks form and propagate, the binder often fails to fill and adapt to these newly generated voids in time, causing some particles to detach from the conductive and binder networks, becoming electrochemically isolated "dead particles" and resulting in irreversible capacity loss. Furthermore, volume changes in secondary particles create stress concentration at the particle-binder interface; if the binder lacks sufficient flexibility or buffering mechanisms, interface separation and failure are likely to occur.

[0041] Third, existing technologies primarily focus on source control and bulk phase regulation, lacking systematic design for the internal structure and local environment of the electrode. While cathode surface coating and electrolyte additives can significantly reduce side reactions and byproduct formation, they mainly act on the particle surface and the electrolyte phase, offering limited control over the microenvironment within the electrode, particularly the three-dimensional porous structure formed by the binder network. In practical applications, the electrode is a complex porous system; the active material particles, conductive agents, binders, and electrolyte-filled pores collectively constitute the electrode's microstructure. The diffusion, accumulation, and reaction behavior of byproducts within this complex structure depends not only on the properties of the particle surface and the electrolyte phase but also on the properties of the internal porous network and binder. Current technologies have yet to achieve control at this internal structural level.

[0042] Fourth, single-function binders are insufficient to address the multiple challenges of high-nickel cathodes. High-nickel cathodes present multifaceted problems, including gas generation, acid corrosion, microcrack propagation, and increased impedance. Traditional binder design focuses on providing a single mechanical bonding function. While some functional binders, such as conductive and self-healing binders, have emerged in recent years, these designs typically address single problems and lack systematic multi-functional integration. There is no systematic solution specifically designed for high-nickel cathodes that can simultaneously address the multiple challenges. Fifth, there is a lack of specialized binder design paradigms for the internal structural stability of high-nickel cathodes. Although the importance of binders is widely recognized, most research remains limited to the selection and simple modification of existing binder materials, lacking systematic research that addresses the specific problems of high-nickel cathodes by focusing on targeted structural design and functional integration.

[0043] In summary, while existing technologies have made significant progress in material coating and electrolyte optimization to address the challenges of high-nickel cathodes, there are still obvious shortcomings in binder functionalization, especially in the regulation of the internal environment of the electrode.

[0044] To address the aforementioned problems, in a typical embodiment of the present invention, a battery cell is provided, comprising a positive electrode, a negative electrode, a separator, and an electrolyte. The positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one side surface of the positive current collector. The positive electrode film layer includes a positive active material, a conductive agent, and a binder. The binder includes a continuous matrix phase material and a dispersed functional domain phase material. The continuous matrix phase material includes an organic polymer. The dispersed functional domain phase material includes organic-inorganic hybrid porous particles, which include porous inorganic oxides and N-heterocyclic organic layers, with the N-heterocyclic organic layers grafted onto the surface of the porous inorganic oxides.

[0045] This invention introduces a two-phase structure design into the binder system: one phase is a continuous matrix material, which serves as a continuous, highly stable polymer matrix providing the main adhesive strength and electrochemical stability, maintaining the basic function of the binder—bonding and fixing the active material particles and conductive agent, and maintaining the integrity of the electrode structure during charge and discharge. The other phase is a dispersed functional domain phase material, which acts as porous, weakly basic functional domains dispersed in the matrix phase. It has a pore distribution ranging from micropores to small mesopores and a high specific surface area. Simultaneously, weakly basic N-heterocyclic functional groups are introduced on its surface or framework, providing adsorption buffering for byproducts inside the electrode and adaptability to structural changes. The synergistic effect of the two phases achieves an organic combination of adhesive performance and multifunctionality.

[0046] The adhesive of the present invention can achieve the following multiple functions.

[0047] Adsorption and buffering of acidic byproducts such as hydrogen fluoride:

[0048] High-nickel cathodes generate strong acidic substances such as hydrogen fluoride under high voltage and high temperature. These acidic substances corrode the cathode material surface and dissolve transition metal ions, which are important factors leading to capacity decay and increased impedance. Dispersed functional domain phase materials within the electrode can preferentially adsorb and partially neutralize these acidic substances through their high specific surface area and weakly basic functional groups, reducing the acidity inside the electrode and slowing down the corrosion of the cathode material and the dissolution of transition metals. Specifically:

[0049] Under high voltage and high temperature conditions, the lithium hexafluorophosphate in the electrolyte of a high-nickel cathode decomposes to produce phosphorus pentafluoride and hydrogen fluoride. Hydrogen fluoride is a strong acid that reacts with transition metal oxides on the surface of the cathode material, dissolving metal ions such as nickel, cobalt, and manganese. These dissolved metal ions migrate inside the electrode, some depositing on the surface of the negative electrode, damaging the solid electrolyte interface film and increasing battery impedance. Simultaneously, the dissolution of transition metals on the cathode surface forms a lithium-rich layer or other phase transition products, reducing the cathode's activity and ion conductivity, leading to capacity decay and increased polarization. Furthermore, the strongly acidic environment accelerates further decomposition of the electrolyte, creating a vicious cycle.

[0050] The dispersed functional domain phase material of this invention is weakly basic and can serve as an "acid buffer" inside the electrode. The functional domains are dispersed in the positive electrode coating, and when acidic substances such as hydrogen fluoride are generated or diffuse inside the electrode, they preferentially contact the nearest weakly basic sites. The high specific surface area of ​​the porous structure greatly increases the contact opportunities between acidic substances and weakly basic functional groups. The N-heterocyclic functional group, as a Lewis base, can interact with protic acids such as hydrogen fluoride to form ammonium salts or complexes. Although this interaction may be reversible under certain conditions, it can effectively reduce the concentration of free hydrogen fluoride inside the electrode, slowing down its corrosion rate on the positive electrode material. Simultaneously, the adsorbed or fixed hydrogen fluoride no longer diffuses freely, reducing the possibility of it reaching the negative electrode and damaging the solid electrolyte interface film.

[0051] This acid buffering effect can delay the dissolution of transition metals on the cathode surface, maintain the stability of the cathode material's surface structure, and thus improve the battery's cycle life. Although the adsorption capacity of the dispersed functional domain phase material is limited and it is impossible to completely eliminate all acidic substances, even partial adsorption and delay can have a cumulative effect during long-term cycling, postponing the onset of severe degradation. This function can also complement cathode surface coating (if any): the coating layer reduces the generation of acidic substances, while the functional domains handle the small amount of unavoidable acidic substances generated, and the two work synergistically to improve corrosion resistance.

[0052] Mechanical buffering against positive electrode particle volume changes and microcracks:

[0053] The volume changes and microcracks generated during the charging and discharging process of high-nickel materials can induce stress at the bonding interface. Porous, dispersed functional domain phase materials possess a certain degree of compressibility and deformability, serving as a local buffer to absorb and disperse some stress, reducing stress concentration at the bonding interface. Simultaneously, the porous structure provides space for localized particle deformation and crack propagation, maintaining contact between particles and the binder network and reducing the formation of "dead particles." Specifically:

[0054] High-nickel materials undergo redox reactions of nickel ions during charging and discharging. Nickel ions in different valence states have different ionic radii, leading to anisotropic variations in lattice parameters. For secondary particles formed by the aggregation of multiple primary particles, the crystal orientations of each primary particle differ, resulting in different expansion and contraction directions during charging and discharging. This generates shear and tensile stresses at the interfaces between primary particles. When the accumulated stress exceeds the material's fracture strength, microcracks will form within the secondary particles. The formation of microcracks has several adverse effects: first, it increases the contact area between the primary particles and the electrolyte, increasing the area of ​​side reactions; second, it may cause some primary particles to separate from the conductive network, forming electrochemically isolated "dead particles"; and third, stress concentration at the crack tip will further promote crack propagation, potentially leading to the complete breakage of the secondary particles.

[0055] While traditional dense binders provide adhesion, their rigidity or lack of buffering mechanisms makes them ineffective in addressing the generation and propagation of microcracks. The porous, dispersed functional domain phase material of this invention provides mechanical buffering. First, the porous structure itself has a certain degree of compressibility. When the cathode particles expand in volume, the adjacent porous, dispersed functional domain phase material can absorb and disperse this volume change through partial compression of the pores, reducing the direct impact on the bonding interface. Second, the porous structure provides a certain amount of free space. When microcracks are generated inside the particles and propagate outwards, if the cracks encounter the porous, dispersed functional domain phase material, the pores can provide space for the small-scale propagation of the cracks, reducing stress concentration at the crack tip and delaying further rapid crack propagation. Third, the porous, dispersed functional domain phase material, dispersed within the binder network, acts as "soft spots," dispersing and dissipating the stress transmitted between particles and preventing excessive stress concentration in certain localized locations.

[0056] This mechanical buffering mechanism slows down the rate of mechanical degradation of the cathode particles, maintains more effective contact between the particles and the conductive and binder networks, reduces the generation of "dead particles," and thus improves capacity retention and cycle stability. This function is particularly important for high-nickel materials, as their volume changes and microcrack problems are more severe than those of conventional ternary materials.

[0057] Partial adsorption and delayed accumulation of gaseous byproducts:

[0058] While complete gas fixation is difficult to achieve in practical systems, porous, dispersed functional domain phase materials can utilize their pore spaces and surface functional groups to provide physical adsorption and chemical interactions for gases such as carbon dioxide, thus slowing down the free diffusion and concentrated accumulation of gases within the electrode's internal pores. This delayed accumulation effect helps postpone the rapid rise in internal electrode pressure, extending the time before macroscopic failure phenomena such as bulging occur. Specifically:

[0059] During high-voltage charging, high-nickel cathodes may release lattice oxygen from the cathode material surface. This can cause oxidative decomposition of the electrolyte, particularly carbonate solvents, producing gases such as carbon dioxide and carbon monoxide. If these gases accumulate in the pores within the electrode, it can increase internal pressure. In pouch cells, this gas accumulation leads to increased cell thickness, a phenomenon known as bulging. Bulging not only affects the battery's appearance and packaging reliability but also alters the contact pressure distribution within the electrodes, potentially causing poor local contact and increased impedance. In severe cases, gas pressure can even lead to separation of the bonding interface, resulting in capacity loss.

[0060] It should be noted that completely eliminating or fixing gases is extremely difficult in practical battery systems. This invention provides partial adsorption and delayed accumulation through porous dispersed functional domain phase materials, an effect based on a dual-channel mechanism. In terms of physical channels, the pore spaces of the porous dispersed functional domain phase material can serve as temporary storage spaces for gas molecules. When gas is generated inside the electrode, some gas molecules diffuse into the pores of the porous dispersed functional domain phase material and are temporarily "stored" in these tiny spaces, rather than immediately accumulating in the macroscopic pores to form bubbles. In terms of chemical channels, N-heterocyclic functional groups interact weakly with carbon dioxide, such as dipole-dipole interactions, hydrogen bonds (if active hydrogen is present), or weak Lewis acid-base coordination. Although these interactions are relatively weak and may be reversible, they can increase the residence time of carbon dioxide on the functional domain surface and reduce its diffusion rate inside the electrode.

[0061] Specifically, the multifunctionality of the dispersed functional domain phase material of this invention is achieved based on the synergistic effect of physical and chemical channels. Physical channels mainly refer to the high specific surface area, pore space, and surface adsorption sites provided by the porous structure. The function of this channel is relatively direct and reliable: the larger the specific surface area, the more opportunities byproduct molecules have to contact the functional domain surface; the pore space can physically accommodate gas molecules and small molecule byproducts, delaying their rapid accumulation in the macroscopic pores of the electrode; the compressibility of the porous structure provides mechanical buffering. The advantage of physical channels lies in their relatively clear mechanism of action and relatively small influence from external conditions such as temperature and voltage, forming the basis of functionality. Chemical channels mainly refer to the chemical interactions between weakly basic N-heterocyclic functional groups and acidic substances, carbon dioxide, etc. These interactions include Lewis acid-base interactions, hydrogen bonds, dipole interactions, and possible weak coordination or partial addition reactions. Chemical channels enhance the selectivity and intensity of interaction of the functional domains with specific substances. For example, for strong acids such as hydrogen fluoride, the basic sites of the N-heterocyclic ring can provide significant acid-base neutralization; for carbon dioxide, although the interaction is relatively weak, it can still increase its affinity on the functional domain surface. The two channels complement each other, forming a robust mechanism of action. Even if the effect of chemical interaction is limited under certain conditions, physisorption and steric accommodative power still play a role; and the introduction of chemical interaction can further enhance the effect based on physisorption. This dual-channel design improves the binder's adaptability to different usage conditions and various byproducts.

[0062] Even if this adsorption and retardation effect only affects a portion of the gas, it can still have a significant macroscopic impact. Bulging and pressure buildup inside the electrode is typically a gradual process; small amounts of gas initially may not cause immediate macroscopic problems, but as the gas accumulates over time, the problem rapidly worsens once a critical point is reached. The binder of this invention can delay this accumulation process, postpone reaching the critical point, and significantly extend the time before battery failure phenomena such as bulging occur in actual use. This is of great value in improving the actual lifespan and safety margin of the battery.

[0063] Improve electrolyte wetting and ion transport:

[0064] Porous, dispersed functional domain phase materials increase the complexity of the pore network inside the electrode, while the polar functional groups on their surface may improve wettability with the electrolyte, contributing to the uniform distribution of the electrolyte within the electrode. This has a positive effect on reducing ion transport resistance inside the electrode and improving its kinetic performance. Specifically:

[0065] Electrode performance depends not only on the active material itself but also on the efficiency of ion transport and charge transfer within the electrode. Uniform distribution and sufficient wetting of the electrolyte within the electrode are crucial for ion transport. While traditional dense binders provide adhesion, their hydrophobicity or poor wettability with the electrolyte can negatively impact electrolyte penetration and distribution within the electrode.

[0066] The porous, dispersed functional domain phase material of this invention can positively influence electrolyte wetting. First, the porous structure itself increases the complexity of the pore network within the electrode, providing more electrolyte penetration pathways. Second, the N-heterocyclic functional groups on the functional domain surface possess a certain polarity, which improves wettability with polar carbonate solvents, making it easier for the electrolyte to wet the functional domain surface and the interior of the pores. The fully wetted porous, dispersed functional domain phase material can act as an "electrolyte reservoir" within the electrode, providing abundant ion transport media locally. This helps reduce ion transport resistance within the electrode, especially in the binder network region, thereby improving the electrode's rate performance and reducing polarization.

[0067] Overall effect:

[0068] The binder provided by this invention complements existing cathode surface coating and electrolyte additive technologies. Surface coating serves as the first line of defense, reducing side reactions and byproducts at the source; electrolyte additives serve as the second line of defense, regulating reaction pathways and interfacial properties in the bulk phase; and the binder of this invention serves as the third line of defense, treating unavoidable residual byproducts within the electrode and providing structural buffering. The synergistic effect of these three lines of defense enables the construction of a more comprehensive high-nickel system stabilization scheme. This invention can improve the performance of high-nickel cathodes under high-voltage cycling and high-temperature storage conditions, including extended cycle life, improved high-temperature capacity retention, reduced bulging tendency, and enhanced overall safety. The binder formulation adjustments required by this invention are compatible with existing cathode preparation processes, requiring no changes to the basic electrode formulation ratios and coating processes, thus demonstrating good engineering feasibility.

[0069] First, this paper proposes introducing dispersed porous weakly basic functional domains into the high-nickel cathode binder system, expanding the traditional simple mechanical bonding function into a multifunctional system integrating bonding, buffering, adsorption, and wetting, providing a new dimension for solving the interface and structural stability of high-nickel cathodes. Second, the paper designs a two-phase structure for the binder: a continuous, highly stable polymer matrix phase provides the main bonding strength and electrochemical stability, while the porous dispersed functional domain phase material provides high specific surface area and weakly basic functional groups. The two phases synergistically achieve a balance between mechanical properties and functionality. Third, the paper addresses the core problems of high-nickel cathodes by preferentially adsorbing and neutralizing acidic byproducts such as hydrogen fluoride, mechanically buffering microcracks and volume changes in cathode particles, partially adsorbing and delaying the accumulation of gaseous byproducts, and improving electrolyte wetting and ion transport, forming a systematic functional framework. Fourth, a dual-channel synergistic mechanism is proposed. The physical adsorption and spatial accommodation of the porous structure serve as the main channels, while the chemical interaction of the weakly basic N-heterocyclic functional groups serves as an auxiliary channel. The two work synergistically to suppress byproducts generated inside the electrode, improving the reliability and applicability of the mechanism. The binder of this invention establishes a complementary relationship with existing cathode surface coating and electrolyte additive technologies, proposing a "three-line defense" synergistic strategy: surface coating as source control, electrolyte additives as bulk phase regulation, and binder as internal buffer, forming a multi-level high-nickel system stabilization scheme.

[0070] In summary, this invention disperses porous, weakly basic functional domains with high specific surface area in the binder. While maintaining bonding strength and electrochemical stability, it achieves partial adsorption and neutralization of acidic byproducts generated inside the electrode, such as hydrogen fluoride; partial adsorption and buffering of gaseous byproducts, such as carbon dioxide; mechanical adaptation to changes in cathode particle volume and microcracks; and improvement of electrolyte wetting and ion transport. The binder of this invention can serve as a supplement to surface coating and electrolyte optimization, and is particularly suitable for the electrode preparation of nickel-cobalt-manganese ternary cathode materials and nickel-cobalt-aluminum ternary cathode materials with a nickel content greater than 80%. It can significantly improve the cycle stability and structural integrity of high-nickel systems under high voltage and high temperature conditions, further enhancing the cycle life, high-temperature storage performance, and safety of high-nickel batteries.

[0071] In a preferred embodiment, the porous inorganic oxide comprises porous silica and / or porous alumina; and / or the material containing an N-heterocyclic organic layer comprises one or more of the following: pyridine and its derivatives, pyrazine, triazine and its derivatives, imidazole and its derivatives, benzimidazole, and 1,2,4-triazole. Preferably, pyridine and its derivatives comprise one or more of pyridine, 2-fluoropyridine, 3-pyridinepropyl, and 4-(trifluoromethyl)pyridine; preferably, triazine and its derivatives comprise one or more of 1,3,5-triazine, melamine, and 2,4-diamino-6-phenyltriazine; preferably, imidazole and its derivatives comprise one or more of imidazole, 2-methylimidazolium, and 4-cyanoimidazolium.

[0072] The inorganic framework of the porous inorganic oxide is stable under high voltage, and mature preparation processes exist to control pore size and porosity. An organic layer containing N-heterocyclic functional groups is grafted onto the surface of the inorganic framework (grafting can be achieved through surface modification techniques, using a silane coupling agent method). These hybrid porous particles combine the structural stability of the inorganic framework with the chemical functionality of the organic functional groups, achieving a balance between mechanical and functional properties. The nitrogen atom in the N-heterocyclic ring possesses a lone pair of electrons, which can act as Lewis base sites, interacting with acidic substances such as hydrogen fluoride, and adsorbing with carbon dioxide through dipole interactions and weak coordination. Compared to aliphatic amines, the material containing the N-heterocyclic organic layer exhibits higher oxidation stability, maintaining relative stability at a positive electrode potential of 4.3–4.5 V.

[0073] This structural design leverages porous oxides to provide a high specific surface area and a stable pore system, effectively supporting and uniformly distributing N-heterocyclic functional groups. The nitrogen atoms in the N-heterocyclic organic layer, due to their lone pair electrons, can engage in strong Lewis acid-base interactions with acidic byproducts such as hydrogen fluoride produced by electrolyte decomposition, achieving efficient adsorption and partial neutralization of acidic substances. This significantly inhibits their accumulation and corrosion on the surface of the positive electrode active material, reduces the risk of dissolution of transition metals such as nickel and cobalt, and improves the structural stability and electrochemical performance of the high-nickel positive electrode during long-term cycling. Simultaneously, the thermal stability and mechanical strength of the porous inorganic framework ensure the structural integrity of the binder under high voltage and high temperature environments, enabling the composite binder to adsorb acidic byproducts without sacrificing electrode flexibility and interfacial adhesion.

[0074] In a preferred embodiment, the porous inorganic oxide has a pore size of 3-15 nm, preferably 5-10 nm; and / or a porosity of 30-70%; and / or a particle size of 50 nm-1 μm, preferably 100-500 nm. The pore size of the porous inorganic oxide falls within the micropore to small mesopore range, providing sufficient channel size for gas molecules such as carbon dioxide and small-molecule acidic substances such as hydrogen fluoride, promoting the diffusion of byproduct molecules. Simultaneously, the smaller pore size is beneficial for generating a higher specific surface area, enhancing adsorption. The porosity of the porous inorganic oxide is preferably within the above range, which is beneficial for providing sufficient pore volume to accommodate byproducts without excessively weakening the mechanical strength of the particles themselves. The particle size of the porous inorganic oxide within the above range is beneficial for promoting the uniform dispersion of functional domains in the matrix phase and also provides sufficient single-particle surface area and pore volume. The synergistic effect of the above parameters enables the organic-inorganic hybrid porous particles to form a high-density, high-specific-surface-area nanoscale adsorption network in the cathode film, achieving synergistic inhibition of "adsorption-neutralization-slow release" of corrosive byproducts, thereby significantly reducing surface corrosion and transition metal dissolution of high-nickel cathode materials and improving battery cycle stability and safety.

[0075] To form a uniform and dense weakly basic functional layer on the surface of porous inorganic oxides, providing a more sufficient density of nitrogen heterocyclic functional groups, effectively adsorbing and neutralizing corrosive substances such as hydrogen fluoride, and without significantly clogging the pores, in a preferred embodiment, the thickness of the N-heterocyclic organic layer is 1~3 nm. Within this thickness range, the porous structure of the organic-inorganic hybrid particles is completely preserved, while the N-heterocyclic groups can efficiently capture and neutralize acidic components generated by electrolyte decomposition, significantly reducing acid etching reactions on the surface of the positive electrode active material, effectively reducing the dissolution of transition metal ions and the destruction of the crystal structure, significantly improving the structural stability and cycle life of the high-nickel positive electrode under high-voltage cycling, and achieving in-situ control and long-term protection of acidic byproducts inside the electrode.

[0076] To regulate the alkalinity, in a preferred embodiment, the N-heterocyclic organic layer contains electron-withdrawing substituents on its N-heterocyclic organic layer. These electron-withdrawing substituents include one or more of trifluoromethyl, fluorine, and cyano groups. The functional group density of these substituents is 0.5–3 mmol per 1 g of dispersed functional domain phase material. These electron-withdrawing substituents can control the basicity of the binder within a more suitable range, thereby reducing side reactions. The functional group density, based on functional domains, is within this range, which helps to provide sufficient functional sites while further reducing mutual interference or stability problems caused by excessive functional group density. These conditions, while ensuring that the N-heterocyclic ring still possesses the ability to weakly neutralize and adsorb acidic byproducts such as hydrogen fluoride, significantly improve the electrochemical stability of the dispersed functional domain phase material. This allows the binder to continuously and stably capture and neutralize acidic substances accumulated on the surface of the cathode material during long-term cycling, reducing corrosion and transition metal dissolution in high-nickel cathodes, ultimately achieving a synergistic improvement in battery cycle life and safety.

[0077] In a preferred embodiment, the dispersed functional domain phase material accounts for 10-30% of the binder by weight, preferably 15-25%; and / or the continuous matrix phase material accounts for 70-90% of the binder by weight, preferably 75-85%. Under these conditions, a better balance between multifunctionality and bonding performance can be achieved. The N-heterocyclic organic layer grafted onto the porous inorganic oxide surface has sufficient density and contact area, thereby efficiently adsorbing and buffering acidic byproducts such as hydrogen fluoride generated inside the positive electrode due to electrolyte decomposition, effectively inhibiting the corrosion of high-nickel positive electrode materials and the dissolution of transition metals. At the same time, the proportion of organic polymers in the continuous matrix phase material is maintained at a high level, ensuring strong bonding force and structural stability of the binder to the positive electrode active material and conductive agent during electrode cycling, reducing mechanical property degradation caused by excessive functional domains, and achieving synergistic optimization between acid adsorption capacity and electrode mechanical integrity, thereby significantly improving the safety and lifespan of the battery under high voltage and long cycle conditions.

[0078] The role of the continuous matrix phase material is to provide the primary bonding strength, fixing and interconnecting the positive electrode active material particles and conductive agent to the current collector surface, while maintaining the integrity of the electrode structure during charge-discharge cycles. The matrix phase should possess sufficient mechanical strength to resist stresses during electrode manufacturing and use, while also exhibiting a degree of flexibility to accommodate volume changes in the active material. The electrochemical stability of the matrix phase is crucial, requiring it to maintain chemical structural stability under high-voltage oxidizing environments and high-temperature conditions, without significant degradation or side reactions. In a preferred embodiment, the organic polymer includes one or more of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyimide, polyethersulfone, and polyetheretherketone.

[0079] The aforementioned organic polymers exhibit good electrochemical stability within the 4.3–4.5V cathode operating voltage range, effectively reducing the loss of mechanical integrity in continuous matrix materials due to swelling, degradation, or functional group deactivation during long-term cycling. The synergistic effect of these organic polymers with dispersed functional domain phase materials formed by porous inorganic oxides grafted with N-heterocyclic organic layers allows the overall binder network to maintain a stable three-dimensional structure under high temperature and high voltage conditions. This enables the N-heterocyclic functional groups to continuously exert their efficient adsorption and neutralization functions on acidic byproducts, thereby further blocking the corrosion pathway of acidic substances on the high-nickel cathode material, significantly reducing the dissolution of transition metal ions, and improving the cycle life and safety of the battery.

[0080] As described above, the binder of the present invention is particularly suitable for electrode preparation of nickel-cobalt-manganese ternary cathode materials and nickel-cobalt-aluminum ternary cathode materials with a nickel content greater than 80%. It can significantly improve the cycle stability and structural integrity of high-nickel systems under high voltage and high temperature conditions, further enhance the cycle life, high-temperature storage performance and safety of high-nickel batteries, and achieve further improvement in the electrochemical performance of high-energy-density batteries. In a preferred embodiment, the cathode active material includes NCM materials and / or NCA materials; and / or the cathode active material includes one or more of high-nickel cathode materials, ultra-high-nickel cathode materials and single-crystal high-nickel materials, wherein the molar percentage of Ni in the total transition metals of the high-nickel cathode material is 80-85%, and the molar percentage of Ni in the total transition metals of the ultra-high-nickel cathode material is greater than 85% and less than or equal to 95%.

[0081] In a preferred embodiment, when the positive electrode active material includes a high-nickel positive electrode material, the dispersed functional domain phase material accounts for 15-25% of the weight of the binder, and the pore size of the dispersed functional domain phase material is 5-10 nm. Optionally, the N-heterocyclic organic layer contains electron-withdrawing substituents, and the functional group density of the electron-withdrawing substituents is 1-2 mmol of electron-withdrawing substituents per 1 g of dispersed functional domain phase material. When the positive electrode active material includes an ultra-high-nickel positive electrode material, the dispersed functional domain phase material accounts for 20-30% of the weight of the binder, and the material containing the N-heterocyclic organic layer includes imidazole and its derivatives. When the positive electrode active material includes a single-crystal high-nickel material, the dispersed functional domain phase material accounts for 10-20% of the weight of the binder.

[0082] High-nickel cathode materials already exhibit significant gas generation and acidic substance problems, but these are still relatively mild compared to ultra-high-nickel materials, and the aforementioned binders can provide a good balance. Ultra-high-nickel cathode materials suffer from more severe gas generation, acid corrosion, and microcrack issues; the content of dispersed functional domain phase materials can be appropriately increased, or functional groups with stronger acid-base interactions can be selected. Simultaneously, these materials have a higher demand for mechanical buffering, and the aforementioned porosity is preferred to enhance buffering capacity. Single-crystal high-nickel materials have relatively milder microcrack problems due to the absence of primary intergranular interfaces within the single-crystal particles, but surface side reactions still exist; therefore, the proportion of dispersed functional domain phase materials can be relatively reduced.

[0083] Furthermore, for high-nickel materials with pre-coating, the burden on the functional binder is relatively light because the surface coating already reduces the generation of source gases and acidic substances. Lower functional domain contents can be used compared to single-crystal high-nickel materials, or the focus can be on improving functionality through mechanical buffering and wetting.

[0084] In a preferred embodiment, the binder accounts for 3-8% of the weight of the positive electrode film, preferably 4-6%; and / or the dispersed functional domain phase material accounts for 0.3-2.4% of the weight of the positive electrode film; and / or the weight ratio of the positive electrode active material, conductive agent and binder in the positive electrode film is (90-96):(2-5):(3-8).

[0085] The aforementioned amount of binder is sufficient to form a dispersed functional network within the electrode without significantly altering the overall mechanical and electrochemical properties of the electrode. The mass ratio of active material, conductive agent, and binder can be maintained within a conventional range, ensuring compatibility with existing cathode formulations. The functional binder of this invention also exhibits good compatibility with different electrolyte systems. For electrolytes containing cathode protective additives such as vinyl sulfate and lithium fluoride phosphide, the functional binder can synergistically work with these additives to form a more comprehensive protection system. For electrolytes using oxidation-resistant solvents such as fluorocarbonates, where gas generation and acidity issues are relatively minor, the functional binder can serve as a further means of enhancing safety margins.

[0086] In another typical embodiment of the present invention, a method for preparing the above-mentioned battery cell of the present invention is also provided. A process flow diagram of the preparation process of the battery cell in one embodiment is shown below. Figure 1As shown, the process includes the following steps: Step S1, mixing a porous inorganic oxide, an N-heterocyclic silane coupling agent, and a first solvent, and performing a hydrolysis-condensation reaction to graft an N-heterocyclic organic layer onto the surface of the porous inorganic oxide, followed by drying to obtain a dispersed functional domain phase material; Step S2, mixing an organic polymer and a second solvent to obtain an organic polymer solution; mixing the organic polymer solution with the dispersed functional domain phase material and an optional dispersant, and dispersing to obtain a solution containing a binder; Step S3, mixing a positive electrode active material, a conductive agent, and a binder-containing solution to obtain a positive electrode slurry; coating the positive electrode slurry onto at least one side of the positive electrode current collector, drying to form a positive electrode film layer, and rolling to obtain a positive electrode sheet; Step S4, assembling the positive electrode sheet, negative electrode sheet, separator, electrolyte, casing, and top cover to obtain a battery cell.

[0087] Preparation of functional domain materials:

[0088] Porous inorganic oxides can be prepared using established processes such as the sol-gel method and the template method. An N-heterocyclic silane coupling agent is mixed with a porous inorganic oxide framework in a suitable solvent, and organic functional groups are grafted onto the inorganic surface through silane hydrolysis and condensation reactions. After the reaction, washing and drying yield surface-functionalized porous particles, i.e., dispersed functional domain phase materials. The ratio of the N-heterocyclic silane coupling agent to the porous inorganic oxide can be determined based on the designed thickness of the N-heterocyclic organic layer.

[0089] Adhesive preparation:

[0090] The continuous matrix phase material is dissolved in a suitable solvent to prepare a solution of a certain concentration. The prepared dispersed functional domain phase material is added to the organic polymer solution according to the designed ratio, and the functional domain particles are uniformly dispersed in the matrix solution by stirring, sonication, etc. A dispersant that does not affect the electrochemical performance of the electrode can be used to assist dispersion. The resulting mixture is the multifunctional binder solution, in which the mass ratio of the dispersed functional domain phase material to the continuous matrix phase material is determined according to the design.

[0091] Preparation of positive electrode slurry:

[0092] The positive electrode active material, conductive agent, and binder solution are mixed according to the designed formula ratio. The mixing process usually adopts a planetary mixer or other high-shear mixing equipment to ensure that the components are evenly dispersed and the viscosity of the slurry is controlled within a suitable range for coating. If necessary, the amount of solvent can be adjusted. The prepared slurry is degassed by vacuum to remove air bubbles.

[0093] A positive electrode active material, a conductive agent, and a binder-containing solution are mixed to obtain a positive electrode slurry. The positive electrode slurry is coated on at least one side of the positive electrode current collector, dried to form a positive electrode film, and rolled to obtain a positive electrode sheet. In step S4, the positive electrode sheet, negative electrode sheet, separator, electrolyte, shell, and top cover are assembled to obtain a battery cell.

[0094] Electrode coating and drying:

[0095] The positive electrode slurry is coated onto at least one side of the positive electrode current collector (such as aluminum foil) using blade coating, slot extrusion coating, or other conventional coating methods. The coating thickness is determined based on the designed areal capacity. The coated electrode is then dried in a drying oven to remove the solvent. The drying process typically employs segmented temperature control: initial low-temperature, slow drying to prevent cracking, followed by high-temperature, rapid drying to improve efficiency. The drying temperature is generally between 80 and 120°C. These drying conditions help maintain the structure and functional groups of the dispersed functional domain phase material.

[0096] Electrode rolling and cutting:

[0097] After drying, the electrode sheets are rolled using a roll press to improve the coating density and adhesion to the current collector. The rolling pressure and gap are adjusted according to the target density, typically with a compaction density of 3.0~3.8 g / cm³. Care must be taken during the rolling process to avoid over-compression, which could damage the pore structure of the dispersed functional domains. The rolled positive electrode sheets are then cut into the required shapes and sizes for subsequent cell assembly.

[0098] Cell assembly and formation:

[0099] The cut positive electrode, negative electrode, separator, shell, and top cover are assembled into a battery cell. Electrolyte is injected, and the cell is allowed to stand to allow for full electrolyte saturation before formation. The formation process follows conventional high-nickel positive electrode formation technology, employing a low-current pre-formation followed by normal formation. For example, the cell can be charged at a constant current of 0.05C to 3.6V, allowed to stand for 1 hour, charged at a constant current of 0.1C to 4.25V, and discharged at a constant current of 0.1C to 2.8V. The binder is compatible with conventional formation processes and requires no special adjustments to the formation conditions.

[0100] The entire process of this invention is highly compatible with existing high-nickel cathode manufacturing processes. The main changes lie in the selection and preparation of the binder; other steps can utilize existing processes and equipment. This gives the invention good engineering feasibility and industrial application potential.

[0101] In a preferred embodiment, in step S1, the N-heterocyclic silane coupling agent includes one or more of (3-pyridylpropyl)trimethoxysilane, triazine silane coupling agent, N-(3-triethoxysilylpropyl)imidazolium, and 2-(trimethoxysilylethyl)pyridine; wherein the raw material for the triazine silane coupling agent includes 3-aminopropyltriethoxysilane and cyanuric chloride; optionally, the N-heterocyclic silane coupling agent further has an electron-withdrawing substituent on its N-heterocyclic ring, the electron-withdrawing substituent including one or more of trifluoromethyl, fluorine, and cyano groups; and / or, in step S1, the porous inorganic... The weight ratio of oxide to N-heterocyclic silane coupling agent is 1:(0.10~0.50); ​​and / or, in step S1, the hydrolysis-condensation reaction temperature is 60~80℃ and the time is 4~8h; and / or, in step S2, the dispersant includes one or more of polyvinylpyrrolidone, polyethylene glycol and sodium dodecylbenzenesulfonate; and / or, in step S2, the weight ratio of organic polymer to dispersion functional domain phase material is (70~90):(10~30); and / or, in step S2, the weight ratio of dispersant to dispersion functional domain phase material is (0.05~0.2):1.

[0102] Using the aforementioned N-heterocyclic silane coupling agents for surface grafting of porous inorganic oxides facilitates the introduction of heterocyclic structures such as pyridine with strong coordination capabilities onto the oxide surface. This significantly enhances the chemical compatibility and interfacial interaction with organic polymer solutions, effectively suppressing material aggregation and sedimentation during dispersion. Simultaneously, these dispersants further optimize the dispersion kinetics and long-term stability of the functional domain phase materials in the binder solution, promoting their nanoscale uniform distribution in the cathode slurry. These conditions facilitate the formation of a continuous and uniform network for the adsorption and neutralization of acidic byproducts within the cathode film, possessing both efficient capture capabilities for corrosive substances such as hydrogen fluoride and a good mechanical buffering effect. This helps address the material corrosion and transition metal dissolution problems caused by localized acid accumulation in high-nickel cathodes, significantly improving the cycle stability and safety of the battery.

[0103] When the N-heterocyclic organic layer contains an electron-withdrawing substituent on its N-heterocyclic ring, an N-heterocyclic precursor with a pre-existing electron-withdrawing substituent can be selected and reacted with 3-chloropropyltrimethoxysilane or 3-chloropropyltriethoxysilane via N-alkylation or nucleophilic substitution to prepare the corresponding N-heterocyclic silane coupling agent, which can then undergo hydrolysis, condensation, and grafting. For example, 4-fluoroimidazole reacts with 3-chloropropyltriethoxysilane via N-alkylation to prepare 4-fluoro-1-[3-(triethoxysilyl)propyl]imidazole; 5-cyanobenzimidazole reacts with 3-chloropropyltrimethoxysilane via nucleophilic substitution to prepare 5-cyano-1-[3-(trimethoxysilyl)propyl]benzimidazole. For triazine silane coupling agents, 3-aminopropyltriethoxysilane can be used as the silane source, and triazine silane coupling agents can be prepared by nucleophilic substitution reaction with cyanuric chloride, and then grafted.

[0104] For similar reasons, in some embodiments, in step S1, the first solvent includes one or more of anhydrous ethanol, a mixed solvent (ethanol and water mixed in a volume ratio of 4:1), and isopropanol. In step S2, the second solvent includes N-methylpyrrolidone; and / or the mass concentration of the binder-containing solution is 5-8 wt%, and the viscosity is 2000-5000 mPa·s (25°C). In step S3, the drying temperature is 80-120°C; and / or the compaction density of the positive electrode sheet is 3.0-3.8 g / cm³.

[0105] This invention, through innovations in multifunctional system design, dual-phase structure, dual-channel mechanism, three-line defense synergy, and engineering simplicity, provides a new technical approach to solving the stability problem of high-nickel ternary cathodes, possessing significant theoretical and practical value. Details are as follows:

[0106] From simple mechanical bonding to multifunctional bonding system design:

[0107] Existing binder technologies primarily focus on providing mechanical bonding functions. Even functional binders, such as conductive binders and self-healing binders, are typically designed for single problems. This invention proposes a multifunctional system design concept for binders, transforming them from passive mechanical connecting elements into functional components that actively participate in the regulation of the electrode's internal environment and structural stabilization. By introducing dispersed porous weakly basic functional domains into the binder, it endows the binder with multiple functions, including adsorption and neutralization of acidic byproducts, partial containment and buffering of gaseous byproducts, mechanical adaptation to particle deformation, and improvement of electrolyte wetting. This innovative concept expands the role of binders from a single dimension to multiple dimensions, providing a new approach to solving the complex problems of high-nickel cathodes. Compared to single-function designs, multifunctional designs can more comprehensively address the multiple challenges of high-nickel systems, generating synergistic effects.

[0108] The dual-phase structure design achieves a balance between mechanical performance and functionality:

[0109] Existing functionalized adhesives often face trade-offs with mechanical properties when introducing new functions. For example, increasing flexibility may reduce strength, and introducing conductive fillers may affect adhesive force. This invention employs a two-phase structure design: a continuous matrix phase material maintains the excellent adhesive properties and electrochemical stability of the highly stable polymer, while a dispersed functional domain phase material provides multiple functions without significantly impairing the overall mechanical properties. This design makes the introduction of functions more rational and controllable. By optimizing the ratio of the two phases and the dispersion of the functional domains, multiple functions can be achieved while maintaining sufficient adhesive strength, which is difficult to achieve with single-phase or simple mixture systems. The two-phase structure also provides design flexibility, allowing for adaptation to different application requirements by adjusting the composition or ratio of either phase, without requiring a complete redesign of the adhesive system.

[0110] Functional priorities and dual-channel mechanism addressing the core pain points of high-nickel cathodes:

[0111] This invention prioritizes buffering against acidic byproducts such as hydrogen fluoride and mechanical adaptation to microcracks in particles, while considering partial gas adsorption and improved wetting as secondary functions. This functional positioning is based on an in-depth analysis of the failure mechanism of high-nickel cathodes, targeting the two core issues of acid corrosion and mechanical degradation. Simultaneously, this invention proposes a dual-channel synergistic mechanism: physical adsorption and spatial containment within the porous structure serve as the primary channel, while chemical interactions with weakly basic functional groups act as the secondary channel. This mechanism design enhances the robustness of the design. The physical channel's function is relatively reliable and direct, ensuring the foundation of the function; the chemical channel enhances the intensity and selectivity of its interaction with specific substances. Even under certain conditions where the effect of chemical interactions is limited, physical adsorption can still play a role, avoiding over-reliance on a single mechanism. Compared to some single-channel designs that rely solely on chemical reactions or physical adsorption, the dual-channel mechanism offers broader applicability and higher reliability.

[0112] Establish a three-tiered defense strategy and clearly define its unique role as an internal buffer for electrodes:

[0113] Existing high-nickel cathode stabilization technologies mainly include cathode surface coating and electrolyte formulation optimization. These technologies primarily act on the particle surface and the electrolyte liquid phase. This invention positions binder functionalization as a third line of defense, providing buffering and regulation at the internal electrode structure level. Specifically, surface coating, as the first line of defense, reduces the generation of side reactions and byproducts at the source; electrolyte additives, as the second line of defense, regulate reaction pathways and interfacial properties in the bulk phase; and the functional binder of this invention, as the third line of defense, treats unavoidable residual byproducts and provides structural buffering.

[0114] In some embodiments, the surface of the positive electrode active material has a coating layer, including alumina and / or aluminum phosphate, to effectively suppress side reactions on the positive electrode surface and reduce the generation of gases and acidic substances. In some embodiments, the electrolyte contains electrolyte additives, including lithium fluoride phosphide and / or vinyl sulfate, to regulate the oxidative stability of the electrolyte and the interfacial reaction pathway to a certain extent.

[0115] This three-pronged defense strategy offers significant advantages. First, the three components operate at different locations: the surface coating is located at the particle / electrolyte interface, the electrolyte additive is in the bulk phase, and the functional binder is within the binder network and pores inside the electrode, achieving complete spatial coverage. Second, their mechanisms of action are complementary: the surface coating prevents side reactions through physical shielding, the electrolyte additive reduces the intensity of side reactions through chemical regulation, and the functional binder buffers and treats existing byproducts through adsorption, forming a complete chain from prevention to treatment. The synergistic effect of these three defenses can produce a 1+1+1>3 effect, significantly improving the overall stability of the high-nickel system. Compared to existing technologies that primarily focus on source control, this invention fills the technological gap in internal electrode buffering, providing a new dimension for improving the performance of high-nickel cathodes.

[0116] The project is easy to implement and highly compatible with existing processes.

[0117] Some advanced stabilization technologies, such as complex surface coatings and novel electrolyte systems, may improve performance, but they often require significant process modifications, specialized equipment or materials, resulting in high engineering difficulty, high costs, and long industrialization cycles. The advantage of this invention lies in its high compatibility with existing cathode manufacturing processes. In the entire cathode formulation, only the binder undergoes functionalization design; the active materials, conductive agents, current collectors, coating processes, rolling processes, and formation processes require no changes or only minor adjustments. This significantly lowers the barrier to entry and reduces the risks associated with technology application. The functionalization of the binder is primarily completed during the binder preparation stage, namely, preparing the dispersed functional domain phase material and dispersing it within the continuous matrix phase material. This step can be completed independently before existing slurry preparation without affecting subsequent processes. For battery manufacturers, adopting the multifunctional binder of this invention is equivalent to changing the binder formulation, rather than rebuilding the production line. This engineering simplicity gives this invention strong potential for industrial application and allows for verification and promotion in a relatively short time.

[0118] Adjustability and adaptability enable universal design:

[0119] Different high-nickel materials (NCM811, NCM9 series, NCA, etc.), different application scenarios (power batteries, energy storage batteries), and different operating conditions (room temperature, high temperature, high rate) require different binders. This invention provides excellent adjustability through a two-phase structure and multi-parameter design. By adjusting parameters such as the content of functional domains, pore size, porosity, functional group type, and density, different needs can be adapted while maintaining the basic design framework. For example, for ultra-high-nickel materials with particularly severe gas generation and acid corrosion problems, the content of functional domains can be increased and more basic functional groups can be selected; for single-crystal high-nickel materials, the content of functional domains can be reduced and the focus can be on acid buffering. This adjustability avoids the dilemma of developing entirely new binder systems for each material, reducing R&D costs and complexity. Based on a unified two-phase multifunctional design framework, a series of binder products can be formed through parameter optimization, covering different high-nickel materials and application scenarios, which is of great significance for industrial applications.

[0120] Overall performance advantages:

[0121] Based on the above, the binder in the battery cell of this invention can improve performance in multiple dimensions compared to existing technologies. By partially adsorbing and neutralizing acidic byproducts such as hydrogen fluoride, corrosion of the cathode material surface and dissolution of transition metals can be slowed, thereby improving cycle life, especially high-temperature cycle performance. By mechanically buffering microcracks and volume changes in cathode particles, more particles can maintain effective contact with the conductive network, reducing "dead particles" and improving capacity retention. By partially adsorbing and delaying the accumulation of gaseous byproducts, the rise in internal electrode pressure can be slowed, extending the time before macroscopic failure phenomena such as bulging occur, thus improving safety and reliability. By improving electrolyte wetting and ion transport, rate performance and polarization may be improved to some extent.

[0122] These performance improvements are synergistic rather than isolated. For example, reducing acid corrosion slows down the degradation of the cathode surface structure, which in turn helps reduce gas generation; mechanical buffering reduces microcracks, which reduces the contact between the new surface and the electrolyte, thus helping to reduce side reactions. This multifunctional synergy can produce a cumulative effect, showing significant advantages in long-term use. Compared to high-nickel cathodes using conventional PVDF binders, cathode sheets using the multifunctional binder of this invention exhibit longer cycle life, higher high-temperature capacity retention, lower bulging tendency, and better safety margin under the same testing conditions. These improvements are of great value for the promotion of high-nickel batteries in applications such as electric vehicles and energy storage.

[0123] In another typical embodiment of the present invention, a battery device is also provided, comprising the battery cell described above. The battery device includes one or more of a battery module, a battery pack, and an energy storage battery. The battery cell of this application can be used, but is not limited to, in electrical devices or energy storage devices such as vehicles, ships, or aircraft, as well as in high-voltage power batteries (electric vehicles), high-energy-density energy storage batteries (grid-level energy storage), high-energy-density consumer electronics batteries, and high-safety batteries for aerospace applications.

[0124] In another typical embodiment of the present invention, an electrical device is also provided, which includes the battery device described above, and the battery device is used to provide electrical energy. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Among them, electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc., and spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0125] In another typical embodiment of the present invention, an energy storage device is also provided, which includes the battery device described above, and the battery device is used to store electrical energy. The energy storage device can be, but is not limited to, an energy storage container, an energy storage cabinet, an energy storage power station, an energy storage battery pack, or a portable energy storage system, etc.

[0126] In long-term energy storage applications, especially for 4-hour, 8-hour, and longer-term energy storage needs, the battery cells of this invention exhibit excellent long-term energy storage performance, significantly improving battery stability during long-term charge-discharge cycles. This stability and energy retention capability significantly improve long-term energy storage, enabling the battery to continuously provide stable power without frequent replacement or maintenance, significantly extending battery life, reducing the overall operating cost of the energy storage system, and improving economic efficiency and reliability.

[0127] Example 1

[0128] The preparation parameters are detailed in Tables 1 and 2.

[0129] Step S1: The porous inorganic oxide (porous silica, parameters are shown in Table 1) and the N-heterocyclic silane coupling agent ((3-pyridylpropyl)trimethoxysilane) are mixed at a weight ratio of 1:0.25, and then mixed with a solvent (a mixed solvent of anhydrous ethanol and deionized water, volume ratio 4:1) to carry out a hydrolysis condensation reaction (temperature 70℃, time 6h) to graft the N-heterocyclic organic layer onto the surface of the porous inorganic oxide. After drying, the dispersed functional domain phase material is obtained.

[0130] Step S2: Mix the organic polymer (polyvinylidene fluoride) and solvent (N-methylpyrrolidone, NMP) to obtain an organic polymer solution; mix the organic polymer solution with a dispersion functional domain phase material and a dispersant (polyvinylpyrrolidone, the weight ratio of dispersant and dispersion functional domain phase material is 0.1:1) and disperse to obtain a binder-containing solution with a mass concentration of 6wt% and a viscosity of 3000 mPa·s (25℃).

[0131] Step S3: According to the weight ratio of positive electrode active material, conductive agent and binder of 94:2:4, the positive electrode active material (NCM811, Ni molar percentage in total transition metal is 81%), conductive agent (conductive carbon black SuperP) and binder solution are mixed to obtain positive electrode slurry; the positive electrode slurry is coated on one side of the positive electrode current collector (aluminum foil, thickness 12μm), dried at 105℃ to form a positive electrode film layer, and rolled to obtain a positive electrode sheet with a compaction density of 3.5g / cm³.

[0132] Step S4: Assemble the positive electrode, negative electrode (artificial graphite negative electrode), separator (polyethylene composite separator, 12μm thick), shell and top cover with an aluminum-plastic film soft pack structure, inject electrolyte (ethylene carbonate / dimethyl carbonate / ethyl methyl carbonate (volume ratio 1:1:1) containing 1mol / L lithium hexafluorophosphate), form (0.05C constant current charging to 3.6V, stand for 1h, 0.1C constant current charging to 4.25V, 0.1C constant current discharging to 2.8V), and perform capacity testing to obtain a single battery cell.

[0133] Examples 2 to 3

[0134] The difference from Example 1 is that the preparation parameters are different, as detailed in Tables 1 and 2.

[0135] Example 4

[0136] The difference from Example 1 is that the preparation parameters are different, as detailed in Table 1.

[0137] Examples 5 to 6

[0138] The difference from Example 2 is that the preparation parameters are different, as detailed in Table 1.

[0139] Examples 7 to 8

[0140] The difference from Example 2 is that the preparation parameters are different, as detailed in Table 2.

[0141] Example 9

[0142] The difference from Example 1 is that in step S1, porous inorganic oxide (porous silica) and N-heterocyclic silane coupling agent ((3-pyridylpropyl)trimethoxysilane) are mixed at a weight ratio of 1:0.10, and then mixed with a solvent (a mixed solvent of anhydrous ethanol and deionized water, volume ratio 4:1) to carry out a hydrolysis condensation reaction (temperature 60°C, time 8h) to graft the N-heterocyclic organic layer onto the surface of the porous inorganic oxide. After drying, a dispersed functional domain phase material is obtained.

[0143] In step S2, the organic polymer (polyvinylidene fluoride) and solvent (N-methylpyrrolidone, NMP) are mixed to obtain an organic polymer solution; the organic polymer solution is then mixed with a dispersing functional domain phase material and a dispersant (polyethylene glycol, with a weight ratio of dispersant to dispersing functional domain phase material of 0.05:1) and dispersed to obtain a binder-containing solution with a mass concentration of 6 wt% and a viscosity of 3000 mPa·s (25℃).

[0144] Example 10

[0145] The difference from Example 1 is that in step S1, porous inorganic oxide (porous silica) and N-heterocyclic silane coupling agent ((3-pyridylpropyl)trimethoxysilane) are mixed at a weight ratio of 1:0.50, and then mixed with a solvent (a mixed solvent of anhydrous ethanol and deionized water, volume ratio 4:1) to carry out a hydrolysis condensation reaction (temperature 80°C, time 4h) to graft the N-heterocyclic organic layer onto the surface of the porous inorganic oxide. After drying, a dispersed functional domain phase material is obtained.

[0146] In step S2, the organic polymer (polyvinylidene fluoride) and solvent (N-methylpyrrolidone, NMP) are mixed to obtain an organic polymer solution; the organic polymer solution is then mixed with a dispersing functional domain phase material and a dispersant (sodium dodecylbenzenesulfonate, with a weight ratio of dispersant to dispersing functional domain phase material of 0.2:1) and dispersed to obtain a binder-containing solution with a mass concentration of 6 wt% and a viscosity of 3000 mPa·s (25℃).

[0147] Comparative Example 1

[0148] The difference from Example 1 is that the adhesive is polyvinylidene fluoride.

[0149] Comparative Example 2

[0150] The difference from Example 1 is that, in step S1, octadecyltrimethoxysilane is used instead of the silane coupling agent containing N-heterocyclic rings.

[0151] Comparative Example 3

[0152] The difference from Example 1 is that in step S1, colloidal SiO2 (BET specific surface area <10m² / g, no obvious mesoporous characteristics) is used to replace the porous inorganic oxide. The rest is the same as in Example 1, that is, an N-heterocyclic organic layer is grafted onto the surface of colloidal SiO2.

[0153] The binders and battery cells of the above embodiments and comparative examples were subjected to performance tests, and the results are shown in Table 3.

[0154] Test method:

[0155] 1. Adhesive

[0156] Thickness of N-heterocyclic organic layer: Confirmed by cross-sectional observation with transmission electron microscopy (TEM) and EDS nitrogen element surface distribution, taking the average value of no less than 5 particles;

[0157] Electron-withdrawing substituent functional group density: The content of F and N elements in the dispersed functional domain phase material was determined by elemental analyzer (EA) and converted into the molar amount of electron-withdrawing substituents per gram of dispersed functional domain phase material (mmol / g) based on the molecular weight of the substituents.

[0158] Pore ​​size: N2 adsorption-desorption method (77K), BJH method for pore size distribution calculation;

[0159] Porosity: N2 adsorption-desorption method (77K), BET method combined with BJH pore volume calculation;

[0160] Particle size: The median particle size Dv50 of the volume distribution was determined by laser diffraction particle size analyzer. The dispersion medium was NMP, and the particle size was determined after ultrasonic dispersion for 30 seconds.

[0161] 2. Battery cell

[0162] Cycle life: At a constant temperature of 25±2℃, after constant current charging at 1C to 4.3V and then constant voltage charging at 0.05C to cut off, and after constant current discharging at 1C to 2.8V, the number of cycles is calculated based on the number of cycles when the discharge capacity drops to 80% of the initial discharge capacity in the third cycle.

[0163] High-temperature storage performance: The battery cells were charged to 100% SOC at 0.5C and stored in a constant temperature chamber at 60±2℃ for 30 days. After being restored to 25℃, they were discharged to 2.8V at 0.5C. The ratio of the discharge capacity after storage to the discharge capacity before storage was calculated (capacity retention rate, %).

[0164] Safety: (characterized by thickness expansion rate after high-temperature storage), in the same batch as the high-temperature storage capacity retention test, the thickness of the cell center was measured with a micrometer before and after storage. Thickness expansion rate = (thickness after storage - thickness before storage) ÷ thickness before storage × 100%.

[0165] Table 1

[0166]

[0167] Table 2

[0168]

[0169] Table 3

[0170]

[0171] As can be seen, Comparative Example 1, due to the use of traditional polyvinylidene fluoride as a binder, lacks the ability to actively treat acidic and gaseous byproducts inside the electrode, and also lacks an effective mechanical buffering mechanism for changes in the volume of the cathode particles. This results in more severe surface corrosion of the high-nickel cathode material, accelerated microcrack propagation, and more significant gas accumulation inside the electrode during high-voltage cycling and high-temperature storage. The overall manifestations are a shorter cycle life, a larger thickness expansion rate during high-temperature storage, and a lower capacity retention rate during high-temperature storage.

[0172] Comparative Example 2 (porous without N-heterocyclic rings) showed an improvement in expansion rate compared to Comparative Example 1, indicating that the porous structure has a certain effect on the physical buffering of gases. Comparative Example 3 (with N-heterocyclic rings but no pores) showed a more significant improvement in high-temperature storage capacity retention compared to Comparative Example 1, indicating that the chemical neutralization of HF by the N-heterocyclic functional groups is an important pathway to suppress the dissolution of transition metals. However, the improvement in Comparative Examples 2 and 3 was significantly weaker than that in Example 1, indicating that the physical channels of the porous structure and the chemical channels of the N-heterocyclic functional groups have a synergistic effect, and the combined effect is better than the individual effects of each.

[0173] As can be seen from the above, the battery cells of the embodiments of the present invention show significant improvements in cycle life, high-temperature storage capacity retention, and high-temperature storage thickness expansion rate. This indicates that the introduction of dispersed porous weakly basic functional domains can effectively alleviate the acid corrosion and gas accumulation problems of high-nickel cathodes and improve the internal structural stability of the electrode. The present invention introduces a multifunctional binder with dispersed porous weakly basic functional domains into the binder system. While maintaining bonding strength and electrochemical stability, it achieves partial adsorption and neutralization of acidic byproducts generated inside the electrode, partial adsorption and buffering of gaseous byproducts, mechanical adaptation to changes in cathode particle volume and microcracks, and improvement of electrolyte wetting and ion transport. This significantly improves the cycle stability and structural integrity of the high-nickel battery system under high voltage and high temperature conditions. Furthermore, it can be seen that the overall effect is better when all process parameters are within the preferred range of the present invention.

[0174] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A battery cell, characterized in that, The device includes a positive electrode, a negative electrode, a separator, and an electrolyte. The positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector. The positive electrode film layer includes a positive active material, a conductive agent, and a binder. The binder includes a continuous matrix phase material and a dispersed functional domain phase material. The continuous matrix phase material includes organic polymers; The dispersed functional domain phase material includes organic-inorganic hybrid porous particles, which include porous inorganic oxides and N-heterocyclic organic layers, wherein the N-heterocyclic organic layers are grafted onto the surface of the porous inorganic oxides.

2. The battery cell according to claim 1, characterized in that, The porous inorganic oxide includes porous silica and / or porous alumina; and / or The material containing the N-heterocyclic organic layer includes one or more of the following materials: pyridine and its derivatives, pyrazine, triazine and its derivatives, imidazole and its derivatives, benzimidazole, and 1,2,4-triazole.

3. The battery cell according to claim 1 or 2, characterized in that, The porous inorganic oxide has a pore size of 3~15nm, a porosity of 30~70%, and a particle size Dv50 of 50nm~1μm.

4. The battery cell according to claim 1 or 2, characterized in that, The thickness of the N-heterocyclic organic layer is 1~3 nm.

5. The battery cell according to claim 1 or 2, characterized in that, The N-heterocyclic organic layer contains electron-withdrawing substituents on its N-heterocyclic organic layer; wherein... The electron-withdrawing substituents include one or more of trifluoromethyl, fluorine, and cyano groups; and / or The functional group density of the electron-withdrawing substituent is: 0.5~3 mmol of the electron-withdrawing substituent per 1g of the dispersed functional domain phase material.

6. The battery cell according to claim 1 or 2, characterized in that, The dispersed functional domain phase material accounts for 10-30% of the weight of the binder; and / or The continuous matrix phase material accounts for 70-90% of the weight of the binder.

7. The battery cell according to claim 1 or 2, characterized in that, The organic polymer includes one or more of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyimide, polyethersulfone, and polyetheretherketone.

8. The battery cell according to claim 1 or 2, characterized in that, The positive electrode active material includes NCM material and / or NCA material; and / or The positive electrode active material includes one or more of high-nickel positive electrode materials, ultra-high-nickel positive electrode materials, and single-crystal high-nickel materials. In the high-nickel positive electrode material, the molar percentage of Ni in the total transition metal is 80-85%, and in the ultra-high-nickel positive electrode material, the molar percentage of Ni in the total transition metal is greater than 85% and less than or equal to 95%.

9. The battery cell according to claim 8, characterized in that, When the positive electrode active material includes the high-nickel positive electrode material, the weight percentage of the dispersed functional domain phase material in the binder is 15-25%, and the pore size of the dispersed functional domain phase material is 5-10 nm. Optionally, the N-heterocyclic organic layer containing the N-heterocyclic organic layer has electron-withdrawing substituents, and the functional group density of the electron-withdrawing substituents is: 1-2 mmol of the electron-withdrawing substituents per 1 g of the dispersed functional domain phase material. When the positive electrode active material includes the ultra-high nickel positive electrode material, the weight percentage of the dispersed functional domain phase material in the binder is 20-30%, and the material containing the N-heterocyclic organic layer includes imidazole and its derivatives. When the positive electrode active material includes the single-crystal high-nickel material, the weight percentage of the dispersed functional domain phase material in the binder is 10-20%.

10. The battery cell according to claim 1 or 2, characterized in that, The binder accounts for 3-8% of the weight percentage of the positive electrode film; and / or The dispersed functional domain phase material accounts for 0.3~2.4% of the weight of the positive electrode film; and / or In the positive electrode film layer, the weight ratio of the positive electrode active material, the conductive agent and the binder is (90~96):(2~5):(3~8).

11. The method for preparing a battery cell according to any one of claims 1 to 10, characterized in that, Includes the following steps: Step S1: The porous inorganic oxide, the N-heterocyclic silane coupling agent and the first solvent are mixed and subjected to a hydrolysis-condensation reaction to graft the N-heterocyclic organic layer onto the surface of the porous inorganic oxide. After drying, a dispersed functional domain phase material is obtained. Step S2: Mix the organic polymer and the second solvent to obtain an organic polymer solution; mix the organic polymer solution with the dispersion functional domain phase material and an optional dispersant, and disperse to obtain a solution containing a binder; Step S3: Mix the positive electrode active material, conductive agent and the solution containing binder to obtain a positive electrode slurry; coat the positive electrode slurry on at least one side of the positive electrode current collector, dry it to form a positive electrode film, and roll it to obtain a positive electrode sheet; Step S4: Assemble the positive electrode, negative electrode, separator, electrolyte, casing and top cover to obtain the battery cell.

12. The method for preparing a battery cell according to claim 11, characterized in that, In step S1, the N-heterocyclic silane coupling agent includes one or more of (3-pyridylpropyl)trimethoxysilane, triazine silane coupling agent, N-(3-triethoxysilylpropyl)imidazolium, 4-fluoro-1-[3-(triethoxysilyl)propyl]imidazolium, 5-cyano-1-[3-(trimethoxysilyl)propyl]benzimidazole, and 2-(trimethoxysilylethyl)pyridine; wherein, the raw materials of the triazine silane coupling agent include 3-aminopropyltriethoxysilane and cyanuric chloride; optionally, the N-heterocyclic silane coupling agent further has an electron-withdrawing substituent on its N-heterocyclic ring, the electron-withdrawing substituent including one or more of trifluoromethyl, fluorine, and cyano groups; And / or, in step S1, the weight ratio of the porous inorganic oxide to the N-heterocyclic silane coupling agent is 1:(0.10~0.50). And / or, in step S1, the temperature of the hydrolysis-condensation reaction is 60~80℃ and the time is 4~8h; And / or, in step S2, the dispersant includes one or more of polyvinylpyrrolidone, polyethylene glycol, and sodium dodecylbenzenesulfonate; And / or, in step S2, the weight ratio of the organic polymer to the dispersed functional domain phase material is (70~90):(10~30). And / or, in step S2, the weight ratio of the dispersant to the dispersion functional domain phase material is (0.05~0.2):

1.

13. A battery device, characterized in that, The battery device includes the battery cell of any one of claims 1 to 10, and the battery device includes one or more of the following: battery module, battery pack, and energy storage battery.

14. An electrical appliance, characterized in that, The electrical device includes the battery device of claim 13, the battery device being used to provide electrical energy.

15. An energy storage device, characterized in that, The energy storage device includes the battery device of claim 13, the battery device being used to store electrical energy.

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