Conductive binder, solid-state battery cell, and preparation method therefor and use thereof

Abstract

The present application relates to the technical field of batteries, and in particular to a conductive binder, a solid-state battery cell, and a preparation method therefor and a use thereof. The solid-state battery cell comprises a positive electrode and a negative electrode, and a solid-state electrolyte layer arranged between the positive electrode and the negative electrode. The negative electrode contains the conductive binder. The conductive binder comprises a polymer having flexible segments and rigid segments, and a conductive carbon material and metal nanoparticles that are combined with the polymer. The conductive binder added to the negative electrode of the solid-state battery cell in the present application forms a three-dimensional conductive network structure by means of the polymer and the conductive carbon material and metal nanoparticles that are combined into the polymer. Therefore, the conductive binder can form a three-dimensional continuous conductive network structure on surfaces of negative electrode materials such as a silicon-based material, not only promoting uniform transport of ions and electrons and increasing the electronic conductivity and ionic diffusion coefficient, but also effectively mitigating volume change of the negative electrode materials during charging and discharging.

Description

Conductive binders, solid-state battery cells, their preparation methods and applications

[0001] This application claims priority to Chinese Patent Application No. 202411698184.3, filed on November 25, 2024, entitled “Conductive Binder, Solid-State Battery Cell and Preparation Method Thereof and Application”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application belongs to the field of battery technology, specifically relating to a conductive binder, a solid-state battery cell, its preparation method, and its application. Background Technology

[0003] Solid-state batteries (SSBs) are a new type of battery where the electrolyte is solid. Compared to traditional liquid batteries, SSBs offer higher energy density and better safety. All-solid-state batteries (ASSBs) are batteries in which all components are solid-state; they utilize solid electrodes and a solid electrolyte, with no liquid inside. All-solid-state batteries offer significant advantages over conventional solid-state batteries (including semi-solid and quasi-solid-state types) in terms of safety, energy density, cycle life, operating temperature range, and charging speed. These advantages make all-solid-state batteries a promising candidate for future applications in electric vehicles, aerospace, and energy storage systems.

[0004] Currently, silicon-based anodes in solid-state batteries suffer from low electronic conductivity and lithium-ion diffusion coefficients, leading to insufficient ion / electron transport within the anode. Furthermore, significant volume expansion and contraction during cycling generate substantial mechanical stress, potentially causing electrode breakage and pulverization. Developing a conductive binder with excellent electronic and ionic conductivity, capable of buffering the volume expansion of the anode material, is crucial for the development of silicon-based anodes in solid-state batteries. Summary of the Invention

[0005] In view of the above problems, this application provides a conductive binder, a solid-state battery cell, a preparation method thereof, and its application to solve the technical problems of low electronic conductivity and ion diffusion coefficient, and large volume deformation during cycling of existing solid-state battery silicon-based and other negative electrodes.

[0006] In a first aspect, this application provides a solid-state battery cell, including a positive electrode and a negative electrode, and a solid electrolyte layer disposed between the positive electrode and the negative electrode. The negative electrode contains a conductive binder, which includes a polymer having flexible segments and rigid segments, as well as conductive carbon materials and metal nanoparticles bonded to the polymer.

[0007] The conductive binder in the negative electrode of the solid-state battery cell provided in this application includes a polymer with flexible and rigid segments, wherein the rigid segments provide strength and rigidity, and the flexible segments provide flexibility and elasticity. This gives the conductive binder a combination of rigidity and flexibility, while also possessing excellent mechanical strength and elasticity. It can effectively mitigate the deformation caused by the volume expansion and contraction of silicon-based and other negative electrode materials during charging and discharging, and reduce the occurrence of electrode cracks. The conductive carbon material not only has excellent conductivity, which can improve the ion transport performance in the negative electrode, but also undergoes a certain volume expansion after lithiation / lithiation insertion. This expansion provides better confinement of the negative electrode material, better filling the gaps between the negative electrode materials and stabilizing the negative electrode material in situ. It can also induce in-situ reconstruction of the three-dimensional structure of the negative electrode material, forming a mechanically reinforced network with high electrical and ionic conductivity. Furthermore, the surface of the lithilated conductive carbon material contains metallic lithium, which can improve the interfacial reactivity. Furthermore, the introduction of metal nanoparticles can increase the electronic conductivity of the negative electrode. Metal nanoparticles can also reduce the overpotential of lithium ions during nucleation, guide the uniform transport of lithium ions between the negative electrode and the electrolyte layer, enhance the interfacial conductivity, guide lithium ion insertion / extraction, and reduce the possibility of side reactions between the electrolyte and the negative electrode. Additionally, during battery charging and discharging, metal nanoparticles can form lithium alloy particles with lithium metal, achieving even higher electronic conductivity together with the metal nanoparticles. The polymer and conductive carbon materials in the conductive binder form a three-dimensional conductive network structure, and the metal nanoparticles are uniformly distributed and bound within this three-dimensional conductive network structure. Therefore, the conductive binder can form a three-dimensional continuous conductive network structure on the surface of silicon-based and other negative electrode materials, which can both promote the uniform transport of ions and electrons, provide high electronic and ionic conductivity, and effectively alleviate the volume deformation of the negative electrode material during charging and discharging.

[0008] In some embodiments, the polymer has at least one of the following characteristics (1) to (5):

[0009] (1) The flexible segment includes at least one of polyethylene glycol methacrylate, polyethylene, polypropylene, polyester, polyamide, polydimethylsiloxane, and polyurethane;

[0010] (2) The rigid segment includes at least one of acrylic acid, dimethylaminoethyl methacrylate, polyacetylene, polyisocyanate, and polyarylamide;

[0011] (3) The mass ratio of the flexible chain segment to the rigid chain segment is (2-3):1;

[0012] (4) The polymer contains at least one functional group selected from ester, amino, and ether bonds;

[0013] (5) The weight-average molecular weight of the polymer is 10,000 to 70,000.

[0014] In some embodiments, the polymer includes rigid segments of acrylic acid and soft segments of polyethylene glycol methacrylate.

[0015] In some embodiments, the polymer has a tensile strength of 200 kPa to 1 MPa.

[0016] In some embodiments, the elastic modulus of the polymer is 300 kPa to 500 kPa.

[0017] These characteristics give the polymer a balance of rigidity and flexibility, along with excellent mechanical strength and elasticity. This helps to better mitigate the deformation caused by volume expansion and contraction of silicon-based and other anode materials during charging and discharging, and reduces the occurrence of electrode cracks.

[0018] In some embodiments, the conductive carbon material is bonded to the polymer via chemical bonding, resulting in good bonding stability.

[0019] In some embodiments, the conductive carbon material includes at least one of single-walled carbon nanotubes, carbon black, carbon fibers, and multi-walled carbon nanotubes. These carbon materials all possess good conductivity, which can improve the ion migration efficiency in the negative electrode.

[0020] In some embodiments, the conductive carbon material includes single-walled carbon nanotubes (SWCNTs). Introducing SWCNTs utilizes volume expansion and induced interfacial reactions to stabilize silicon-based and other anode materials in situ.

[0021] In some embodiments, the average outer diameter of the single-walled carbon nanotube is 1 nm to 2 nm, the length is not less than 5 μm, and the aspect ratio is 2000 to 10000; a larger aspect ratio is more conducive to the formation of a three-dimensional conductive network.

[0022] In some embodiments, the bonding between the single-walled carbon nanotubes and the polymer includes ester bonding.

[0023] In some embodiments, the particle size Dv50 of the metal nanoparticles is 20nm to 100nm; the small particle size of the metal nanoparticles has a better deposition induction effect on lithium ions and reduces the overpotential of lithium ions during the nucleation process.

[0024] In some embodiments, the metal nanoparticles contain at least one metal selected from silver, gold, magnesium, and bismuth. These metallic materials all possess high electronic conductivity and can reduce the overpotential of lithium ions during nucleation.

[0025] In some embodiments, the metal nanoparticles include silver nanoparticles. Silver nanoparticles have higher electronic conductivity and can better reduce the overpotential of lithium ions during nucleation.

[0026] In some embodiments, the conductive binder contains 5% to 20% by mass of the conductive carbon material and 5% to 20% by mass of the metal nanoparticles; this ensures sufficient improvement in the electronic conductivity and ion diffusion coefficient of the negative electrode, and the formed three-dimensional conductive network effectively alleviates the volume expansion and contraction of silicon-based and other negative electrode materials during cyclic charging and discharging.

[0027] In some embodiments, the conductive binder comprises a polymer having rigid segments of acrylic acid and flexible segments of polyethylene glycol methacrylate, wherein single-walled carbon nanotubes are chemically bonded and silver nanoparticles are grown in situ in the polymer.

[0028] In some embodiments, the conductive binder has a mass percentage content of 2% to 20% in the active layer of the negative electrode; this significantly improves the electronic conductivity and ionic conductivity of the negative electrode, while effectively alleviating the volume expansion and contraction deformation stress of silicon-based and other negative electrode materials during cyclic charging and discharging.

[0029] In some embodiments, the negative electrode material includes silicon-based materials.

[0030] In some embodiments, the solid electrolyte layer includes a sulfide solid electrolyte.

[0031] Secondly, this application provides a method for preparing a battery cell, comprising the following steps:

[0032] A conductive binder is prepared, the conductive binder comprising a polymer having flexible and rigid segments, and conductive carbon materials and metal nanoparticles bonded to the polymer;

[0033] Prepare a negative electrode containing the conductive binder;

[0034] A positive electrode and a solid electrolyte are provided, and the positive electrode, the solid electrolyte and the negative electrode are assembled to obtain a battery cell.

[0035] This application discloses a method for preparing solid-state battery cells. The conductive binder obtained comprises a polymer with flexible and rigid chain segments, and conductive carbon materials and metal nanoparticles bonded to the polymer. When applied to the negative electrode, this conductive binder can form a three-dimensional continuous conductive network structure on the surface of silicon-based or other negative electrode materials. This promotes uniform ion and electron transport, improves electron conductivity and ion diffusion coefficient, and effectively mitigates volume deformation of the negative electrode material during charge and discharge. This not only improves the cycle stability of the prepared solid-state battery cells but also increases ionic conductivity, meaning ions can move rapidly within the electrode material, thereby accelerating the battery's charge and discharge speed. Furthermore, higher ionic conductivity results in higher power density, thus increasing the battery's energy density and enabling it to store more energy. Additionally, high ionic conductivity helps reduce internal resistance and heat generation during charge and discharge, thereby slowing down battery aging and extending battery life. Furthermore, increased electronic conductivity means that electrons can travel rapidly within the electrode material, thereby improving signal transmission speed and response time. This helps reduce electron transport resistance within the battery, thus lowering internal resistance and improving battery efficiency. Higher electronic conductivity results in greater energy density, allowing the battery to store more energy within the same volume or weight.

[0036] In some embodiments, the preparation steps of the conductive adhesive include:

[0037] The polymer is prepared by free radical polymerization of monomers containing flexible segments and monomers containing rigid segments.

[0038] A conductive carbon material grafted with oxygen-containing groups is subjected to a condensation reaction with the polymer to chemically bond the conductive carbon material to the polymer, thereby obtaining an intermediate product.

[0039] After the intermediate product is mixed with a metal salt, the metal salt undergoes a self-decomposition reaction, generating the metal nanoparticles in situ within the intermediate product, thus obtaining the conductive binder.

[0040] This application involves preparing a polymer via free radical polymerization, followed by a condensation reaction with a conductive carbon material grafted with oxygen-containing groups. This chemically bonds the conductive carbon material to the polymer, forming a three-dimensional conductive network structure. After mixing with a metal salt, the metal salt undergoes a self-destruction reaction, generating in-situ silver nanoparticles within the intermediate product. This ensures the metal nanoparticles are uniformly distributed within the three-dimensional conductive network structure of the polymer and conductive carbon material, resulting in an ionic / electron dual-conductive binder. Furthermore, its three-dimensional conductive network structure can accommodate the volume deformation of the negative electrode material during charge and discharge processes.

[0041] In some embodiments, the temperature conditions for the free radical polymerization reaction are 50°C to 80°C, and the reaction time is 2 hours to 5 hours. This promotes the free radical polymerization of both flexible and rigid segments.

[0042] In some embodiments, the condensation reaction conditions include: reacting at a temperature of 65°C to 75°C for 1 to 3 hours; which can promote the condensation reaction between the oxygen-containing groups grafted on the surface of the conductive carbon material and the polymer, so that the conductive carbon material is chemically bonded to the polymer.

[0043] In some embodiments, the conditions for the self-decomposition reaction include: stirring and mixing for 3 to 5 hours, followed by reaction at a temperature of 70°C to 80°C for 6 to 10 hours. This allows the metal salt to be reduced in situ within the three-dimensional conductive network structure of the polymer and conductive carbon material to generate metal nanoparticles.

[0044] In some embodiments, the mass ratio of the flexible segment to the rigid segment is (2-3):1; ensuring that the polymer has both rigidity and flexibility, so that the conductive adhesive has both excellent mechanical strength and elasticity.

[0045] In some embodiments, the mass ratio of the conductive carbon material, the metal nanoparticles, and the polymer in the conductive binder is (5-20):(5-20):(60-90). This ensures sufficient improvement in the electronic conductivity and ion diffusion coefficient of the negative electrode, and the formed three-dimensional conductive network can effectively alleviate the volume expansion and contraction of silicon-based and other negative electrode materials during cyclic charging and discharging.

[0046] In some embodiments, the free radical polymerization reaction is carried out under the action of an initiator, which includes at least one of ammonium persulfate, potassium persulfate, ammonium persulfate / sodium bisulfite, potassium persulfate / sodium bisulfite, potassium persulfate / silver nitrate, persulfate / thiol, cumene hydroperoxide / ferrous chloride, potassium persulfate / ferrous chloride, and hydroperoxide / ferrous chloride; all of which can initiate a free radical polymerization reaction between flexible and rigid segments.

[0047] In some embodiments, the solvent used in the self-decomposition reaction includes at least one of N,N-dimethylformamide, dimethylacetamide (DMAC), dimethylpropionamide (DMP), diethylformamide (DEF), and diethylacetamide (DEAC).

[0048] In some embodiments, the metal salt includes at least one of silver salt, gold salt, magnesium salt, and bismuth salt.

[0049] In some embodiments, the polymer includes rigid segments of acrylic acid and soft segments of polyethylene glycol methacrylate;

[0050] In some embodiments, the conductive carbon material grafted with oxygen-containing groups includes single-walled carbon nanotubes with hydroxyl and / or carboxyl groups grafted onto their surface.

[0051] In some embodiments, the metal nanoparticles include silver nanoparticles.

[0052] Thirdly, this application provides a battery device, including the above-described battery cell or a solid-state battery cell prepared by the above-described preparation method.

[0053] The battery device provided in this application is based on the solid-state battery cell of this application. Therefore, the battery device of this application has a good cycle life under the premise of high energy density.

[0054] Fourthly, this application provides an electrical device comprising the aforementioned solid-state battery cell, or a solid-state battery cell prepared by the aforementioned preparation method, or the aforementioned battery device.

[0055] The electrical device provided in this application is based on the solid-state battery cell or battery device of this application, and therefore the electrical device of this application can work safely and for a long time.

[0056] Fifthly, this application provides an energy storage device, including the above-described solid-state battery cell, or a solid-state battery cell prepared by the above-described preparation method, or the above-described battery device.

[0057] Since the energy storage device of this application contains the solid-state battery cells or battery devices described above, the energy storage device has high energy density, good cycle performance, and long service life.

[0058] In a sixth aspect, this application provides a conductive adhesive comprising a polymer having flexible and rigid segments, and conductive carbon materials and metal nanoparticles bonded to the polymer.

[0059] In this application, the conductive binder forms a three-dimensional conductive network structure composed of polymers, conductive carbon materials, and metal nanoparticles. This structure can form a three-dimensional continuous conductive network on the surface of the electrode material, which can promote the uniform transport of ions and electrons, provide conductivity based on electrons and ions, and effectively alleviate the volume deformation of the electrode material during charging and discharging.

[0060] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0061] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0062] Figure 1 is a schematic diagram of a solid-state battery cell according to an embodiment of this application;

[0063] Figure 2 is an exploded view of the solid-state battery cell shown in Figure 1;

[0064] Figure 3 is a schematic diagram of one embodiment of the battery module of this application;

[0065] Figure 4 is a schematic diagram of one embodiment of the battery pack of this application;

[0066] Figure 5 is an exploded view of the battery pack shown in Figure 4.

[0067] Figure 6 is a schematic diagram of one embodiment of an electrical device that uses a secondary battery as a power source according to an embodiment of this application;

[0068] The reference numerals in the detailed embodiments are as follows: 10-Solid-state battery cell; 11-Housing casing; 12-Top cover assembly; 13-Electrode assembly; 20-Battery module; 30-Battery pack; 31-Upper housing; 32-Lower housing. Detailed Implementation

[0069] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0070] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0071] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0072] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0073] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0074] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0075] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0076] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0077] The term "SSE" is an abbreviation for "Solid State Electrolytes," which stands for solid-state electrolyte and is an important component of solid-state lithium metal batteries (LMBs).

[0078] The term "SSBs" is an abbreviation for "Solid-state batteries," which are a new type of battery with a solid electrolyte.

[0079] The term "ASSBs" is an abbreviation for "All-Solid-State Batteries," which means all-solid-state batteries. All components of the battery are "solid-state," and it is a type of battery that uses solid electrodes and solid electrolytes, with no liquid inside.

[0080] The term "sulfide ASSBs," or all-solid-state sulfide batteries, refers to batteries that use sulfide solid-state electrolytes instead of traditional liquid electrolytes. Their working principle involves the migration of lithium ions through ion conduction within the solid electrolyte, thus completing the charging and discharging process. As a novel all-solid-state battery technology, sulfide ASSBs offer advantages such as high safety, high energy density, long cycle life, and a wide operating temperature range, making them promising for applications in electric vehicles, aerospace, and energy storage systems. With continuous technological advancements and cost reductions, sulfide ASSBs are expected to become one of the mainstream battery technologies in the future.

[0081] Currently, from a market perspective, solid-state batteries offer higher energy density and better safety compared to traditional liquid batteries. All-solid-state batteries, in particular, offer even greater safety (no risk of electrolyte leakage, non-flammable and non-explosive), higher energy density (wider range of material choices, simplified structure reducing the use of encapsulation materials), longer cycle life (stable electrolyte structure, high stability to lithium metal inhibiting lithium dendrite growth), a wider operating temperature range, and faster charging speeds. These advantages make all-solid-state batteries a promising candidate for future applications in electric vehicles, aerospace, and energy storage systems.

[0082] The applicant found that silicon-based and other anode materials in solid-state batteries currently face the following challenges: (1) low electronic conductivity (σe<10) -5 S cm -1 ) and lithium-ion diffusion coefficient (D Li+ 10 -14 -10 -13 cm 2 S -1(2) The significant volume expansion (>300%) and contraction of silicon-based anode materials during cycling generate enormous mechanical stress, leading to electrode fracture and pulverization. Furthermore, the periodic expansion and contraction of silicon-based anodes during lithiation / delithiation exacerbates structural degradation, resulting in electrode cracks. These cracks, caused by large volume changes, pose a significant obstacle to ion / electron transport.

[0083] To enhance electron transport efficiency, conductive carbon additives, such as conductive carbon black and carbon nanotubes, are often introduced into the electrodes. These additives offer advantages like high electronic conductivity and light weight, and are frequently incorporated into electrodes to improve their electronic conductivity. This strategy has been extended from liquid battery systems to solid-state battery systems. However, the ionic conductivity of solid-state battery systems requires the addition of a solid electrolyte. Unfortunately, contact between conductive carbon additives and electrolytes such as sulfides can trigger side reactions. Specifically, the introduction of carbon additives promotes the decomposition of the solid electrolyte (SSE) and the formation of LiCl. Consequently, the crystal structure of the solid electrolyte degrades. This, in turn, significantly affects the ionic conductivity of electrolytes such as sulfides, increases impedance and polarization in all-solid-state batteries, and negatively impacts the cycle stability of silicon-based anodes. Furthermore, introducing conductive additives or solid electrolytes cannot mitigate structural damage such as cracks caused by anode volume deformation. These rigid particles, such as conductive additives or solid electrolytes, cannot adapt to the structural damage caused by deformation stress in silicon-based anodes, thus limiting the development of solid-state batteries.

[0084] In some implementations, the binder used in the solid-state battery anode is PEDOT:PSS-PPP (poly(3,4-ethylenedioxythiophene):polystyrene sulfonate-poly(p-phenylene),) a three-dimensional network electronic / ionic conductive binder. While PEDOT:PSS-PPP exhibits good flexibility as a binder, for silicon anode systems, the pressure changes caused by volume expansion are enormous, often exceeding 10 MPa. The flexible chain segments cannot withstand such high pressure changes, frequently leading to secondary failure of electron / ion channels during cycling. Furthermore, as a conductive polymer, its intrinsic electronic conductivity is relatively poor.

[0085] Based on the above considerations, and in order to address the technical problems of low electronic conductivity and ion diffusion coefficient, as well as large volume deformation during cycling, existing solid-state battery anodes such as silicon-based electrodes have been developed through in-depth research. This application presents a conductive binder for solid-state battery anodes that exhibits excellent electronic and ion conductivity and can buffer the volume expansion of silicon-based anodes.

[0086] For ease of understanding, this application is specifically described through the following embodiments. It should be understood that the following embodiments are only used to illustrate the solution of this application and are not intended to limit the scope of this application.

[0087] Solid-state battery cell 10

[0088] In a first aspect, embodiments of this application provide a solid-state battery cell. In some embodiments, as shown in FIG1, the solid-state battery cell 10 of this application includes a positive electrode and a negative electrode, and a solid electrolyte layer disposed between the positive electrode and the negative electrode. The negative electrode contains a conductive binder, which includes a polymer having flexible segments and rigid segments, as well as conductive carbon materials and metal nanoparticles bonded to the polymer.

[0089] In the solid-state battery cell 10 of this application embodiment, the negative electrode is the electrode with a lower potential in the battery, typically the electrode where oxidation (i.e., electron loss) occurs in the internal electrochemical reaction of the battery. The positive electrode is the electrode with a higher potential in the battery, typically the electrode where reduction (i.e., electron absorption) occurs in the internal electrochemical reaction of the battery. The solid electrolyte layer refers to the electrolyte layer in solid form, which plays the role of transporting ions and blocking electrons. Compared with liquid electrolytes, solid electrolytes have the characteristics of being leak-proof, non-deteriorating, and easy to transport. The main function of the conductive binder in the negative electrode is to tightly bond the main negative electrode material together and fix it on the current collector. This bonding effect ensures the stability and integrity of the negative electrode structure and prevents the negative electrode material from falling off or pulverizing during charging and discharging. The conductive binder also has conductive properties, which can establish conductive channels between the particles of the main negative electrode material and between the main negative electrode material and the current collector, thereby reducing the impedance of electron transfer, increasing the electron mobility, and ensuring that the negative electrode has good conductivity. At the same time, it can also buffer the volume change of the main negative electrode material. Flexible and rigid segments are two distinct components of polymer molecular chains. Flexible segments, also known as soft segments, are typically composed of oligomeric polyols. These segments are characterized by their ability to freely coil into random coils in solution, exhibiting significant expansion and contraction capabilities. Flexible segments impart excellent elasticity, flexibility, and ductility to polymers, enabling them to adapt to various deformations and stresses. Rigid segments, also known as hard segments, have a relatively fixed structure and cannot freely coil into random coils in solution, exhibiting higher strength and hardness. These segments act as support and reinforcement in polymers, resulting in higher heat resistance, stability, and mechanical strength.

[0090] The conductive binder in the negative electrode of the solid-state battery cell 10 provided in this application embodiment includes a polymer with flexible and rigid segments, wherein the rigid segments provide strength and rigidity, and the flexible segments provide flexibility and elasticity. This gives the conductive binder a combination of rigidity and flexibility, while also possessing excellent mechanical strength and elasticity. It can effectively mitigate the deformation caused by volume expansion and contraction of silicon-based and other negative electrode materials during charging and discharging, and reduce the occurrence of electrode cracks. Furthermore, conductive carbon materials and metal nanoparticles are bonded to the polymer, forming a three-dimensional conductive network structure. The metal nanoparticles are uniformly distributed and bonded within this three-dimensional conductive network structure. Therefore, the conductive binder can form a three-dimensional continuous conductive network structure on the surface of silicon-based and other negative electrode materials, which can both promote the uniform transport of ions and electrons and effectively mitigate the volume deformation of the negative electrode material during charging and discharging. Conductive carbon materials possess excellent conductivity, enhancing ion transport performance in the negative electrode. Furthermore, after lithiation / lithiation insertion, the conductive carbon material undergoes volume expansion, providing better confinement of the negative electrode material and filling the gaps between them, thus stabilizing the material and maintaining its in-situ state. It can also induce in-situ reconstruction of the three-dimensional structure of the negative electrode material, forming a mechanically reinforced network with high electrical and ionic conductivity. Additionally, the surface of the lithilated conductive carbon material contains metallic lithium, improving interfacial reactivity. Moreover, the introduction of metal nanoparticles increases the electronic conductivity of the negative electrode. These nanoparticles also reduce the overpotential during lithium ion nucleation, guiding uniform lithium ion transport between the negative electrode and electrolyte layer, enhancing interfacial conductivity, guiding lithium ion insertion / extraction, and reducing the likelihood of side reactions between the electrolyte and negative electrode. Furthermore, during battery charging and discharging, metal nanoparticles can form lithium alloy particles with lithium metal, achieving even higher electronic conductivity together with the metal nanoparticles.

[0091] In some embodiments, the flexible segments in the polymer include at least one selected from polyethylene glycol methacrylate (PEGDA), polyethylene, polypropylene, polyester, polyamide, polydimethylsiloxane, and polyurethane. In this case, these flexible segments in the polymer can provide high flexibility and elasticity, thereby improving the deformation stress of the conductive binder on silicon-based or other negative electrode materials. In some specific embodiments, the flexible segments include polyethylene glycol methacrylate.

[0092] In some embodiments, the rigid segments in the polymer include at least one selected from acrylic acid (PAA), dimethylaminoethyl methacrylate (DMAEMA), polyacetylene, polyisocyanate, and polyarylamide. In this case, these rigid segments all have high glass transition temperatures, and the homopolymer is solid at room temperature, exhibiting relatively rigid physical properties. When co-formed with other flexible segments to constitute a copolymer, the rigid segments provide strength and rigidity, while the flexible segments provide flexibility and elasticity. In some specific embodiments, the rigid segments include acrylic acid.

[0093] In some embodiments, the mass ratio of flexible segments to rigid segments in the polymer is (2-3):1. Flexible segments are more easily deformed, thus giving the polymer better bending and stretching properties. As the proportion of flexible segments increases, the elasticity and flexibility of the polymer are generally enhanced. Rigid segments have a more compact and ordered molecular structure, capable of forming a high-strength crystalline structure, thereby enhancing overall strength. As the proportion of rigid segments increases, the strength and hardness of the polymer are generally improved. In this case, the mass ratio of flexible segments to rigid segments ensures a balance of rigidity and flexibility in the polymer. This allows the conductive binder to possess both excellent mechanical strength and elasticity, effectively mitigating the deformation caused by volume expansion and contraction of silicon-based and other negative electrode materials during charging and discharging, and reducing the occurrence of electrode cracks. Exemplarily, the mass ratio of flexible segments to rigid segments can be any typical but non-limiting point value or a range between any two points, such as 2:1, 2.5:1, or 3:1.

[0094] In some embodiments, the polymer contains at least one functional group selected from ester, amino, and ether bonds. These functional groups exhibit almost no side reactions with electrolytes such as sulfide solid electrolytes (LPSCs), significantly improving the stability of systems such as sulfide all-solid-state batteries. In some embodiments, these functional groups, such as ester, amino, and ether bonds, are linked as side branches in the polymer.

[0095] In some embodiments, the solid electrolyte layer includes a sulfide solid electrolyte. Sulfide solid batteries are currently a research hotspot. A sulfide solid battery refers to a battery that uses sulfides as the solid electrolyte and is equipped with solid electrodes (such as positive and negative electrodes). Sulfide solid electrolytes have high ionic conductivity, good safety, and high energy density. However, sulfur-based solid electrolytes are sensitive to air and easily undergo severe side reactions with air, producing highly toxic gases such as hydrogen sulfide (H2S). This characteristic makes the method of adding sulfur-based solid electrolytes to the negative electrode face compatibility issues with industrial standard coating preparation methods. It is difficult to prepare sulfur-based solid electrolyte negative electrodes through efficient coating processes, making large-scale manufacturing more challenging. However, the conductive binder provided in this application contains ester groups, amino groups, ether bonds, and other functional groups that hardly react with the sulfide electrolyte, thus improving the stability of the sulfide electrolyte to the negative electrode binder.

[0096] In some embodiments, the weight-average molecular weight of the polymer is between 10,000 and 70,000. Exemplarily, the weight-average molecular weight of the polymer can be any typical but non-limiting point value or a range between any two points, such as 10,000, 20,000, 30,000, 40,000, 50,000, 60,000, or 70,000. In some embodiments, the weight-average molecular weight of the polymer is between 30,000 and 50,000. At this molecular weight, the polymer exhibits better mechanical properties.

[0097] In some embodiments, the polymer includes rigid segments of acrylic acid and flexible segments of polyethylene glycol methacrylate. In this case, the polymer comprises rigid segments of acrylic acid (AA) and flexible segments of polyethylene glycol methacrylate (PEGMA), which contain functional groups such as ester groups, amino groups, and ether bonds, and exhibits good stability relative to solid electrolytes such as sulfides.

[0098] In some embodiments, the tensile strength of the polymer is 200 kPa to 1 MPa; exemplaryly, the tensile strength of the polymer can be any typical but non-limiting point value or a range between any two points, such as 200 kPa, 300 kPa, 400 kPa, 500 kPa, 600 kPa, 700 kPa, 800 kPa, 900 kPa, and 1000 kPa. In this case, the tensile strength can better ensure the tight bonding between the silicon particles and other negative electrode materials, ensuring the continuity of the electronic and ionic pathways.

[0099] In some embodiments, the elastic modulus of the polymer is between 300 kPa and 500 kPa. Exemplarily, the elastic modulus of the polymer can be any typical but non-limiting point value or a range between any two points, such as 300 kPa, 350 kPa, 400 kPa, 450 kPa, and 500 kPa. This ensures that the binder has sufficient viscoelasticity to dissipate the large deformation generated during the expansion of the silicon or other negative electrode materials.

[0100] In some embodiments, the polymer comprises rigid acrylic acid segments and flexible polyethylene glycol methacrylate segments in a mass ratio of (2-3):1, with a weight-average molecular weight of 10,000-70,000, a tensile strength of 200 kPa-1 MPa, and an elastic modulus of 300 kPa-500 kPa. In this case, the polymer possesses both rigidity and flexibility, exhibiting excellent mechanical strength and elasticity, which better mitigates the deformation caused by volume expansion and contraction of silicon-based and other negative electrode materials during charging and discharging, and reduces the occurrence of electrode cracks.

[0101] In some embodiments, the bonding between the conductive carbon material and the polymer includes chemical bonding. This chemical bonding encompasses the formation process and the result of chemical bonds. In the conductive binder of this application, a portion of the conductive carbon material and the polymer are bonded together through chemical reactions such as condensation, forming chemical bonds between the conductive carbon material and the polymer, resulting in good bonding stability. Alternatively, a portion of the one-dimensional or two-dimensional conductive carbon material can be bonded to the polymer through intertwining. The conductive carbon material and the polymer form a stable three-dimensional conductive network structure through various bonding methods.

[0102] In some embodiments, the conductive carbon material includes at least one of single-walled carbon nanotubes, carbon black, carbon fibers, and multi-walled carbon nanotubes. These carbon materials all possess good conductivity, which can improve the ion migration efficiency in the negative electrode.

[0103] In some embodiments, the conductive carbon material includes single-walled carbon nanotubes. In this case, the single-walled carbon nanotubes are rolled from a single layer of graphite, resulting in a simpler structure, better uniformity, fewer defects, and stable chemical properties. Due to their high length-to-diameter ratio, they can form an intertwined three-dimensional conductive network with the polymer at extremely low addition levels, preventing structural damage to the anode material during charging and discharging. The formed network structure allows for in-situ reconstruction. Furthermore, this three-dimensional conductive network exhibits excellent conductivity; its strong carbon-carbon bonds enable higher current carrying capacity, further improving the ionic conductivity of the anode. Moreover, single-walled carbon nanotubes possess high elastic modulus and tensile strength, with an elastic modulus approaching that of diamond, and good flexibility, allowing for better bending, twisting, or kinking, mitigating volume deformation of silicon-based and other anode materials during charging and discharging.

[0104] In some embodiments, the volume expansion caused by lithiation of the anode material, such as silicon-based particles, generates approximately 14% tensile strain in the single-walled carbon nanotubes, which in turn strengthens the chemical interaction between Li and C. This chemical-mechanical coupling effect promotes the transformation of sp2-C bonds to sp3 hybridized Li-C bonds at defects in the single-walled carbon nanotubes, which also triggers the formation of new Si-C chemical bonds at the interface. In this process, the single-walled carbon nanotubes can also induce in-situ reconstruction of the three-dimensional structure of the anode material, forming a mechanically reinforced network with high electrical and ionic conductivity.

[0105] In some embodiments, the average outer diameter of the single-walled carbon nanotubes is 1 nm to 2 nm, the length is not less than 5 μm, and the aspect ratio is 2000 to 10000. In this case, the small diameter and long length of the single-walled carbon nanotubes, along with the larger aspect ratio, are more conducive to the formation of a three-dimensional conductive network. This avoids structural damage to silicon-based and other negative electrode materials during charging and discharging, and the formed network structure allows for in-situ reconstruction. For example, the average outer diameter of the single-walled carbon nanotubes can be any typical but non-limiting point value such as 1 nm or 2 nm, or a range between any two points; the length can be any typical but non-limiting point value such as 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, or 20 μm, or a range between any two points; and the aspect ratio can be any typical but non-limiting point value such as 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, or 10000, or a range between any two points.

[0106] In some embodiments, the bonding between single-walled carbon nanotubes and polymers includes ester bonding. In this case, ester bonding is formed between the single-walled carbon nanotubes and polymers through condensation reactions between hydroxyl and carboxyl groups, resulting in a stable three-dimensional conductive network structure.

[0107] In some embodiments, the particle size Dv50 of the metal nanoparticles is 20 nm to 100 nm. In this case, the small particle size of the metal nanoparticles has a better deposition-inducing effect on lithium ions, reduces the overpotential of lithium ions during the nucleation process, guides the uniform transport of lithium ions between the negative electrode and the electrolyte layer, and enhances the conductivity between the interfaces. Exemplarily, the particle size Dv50 of the metal nanoparticles can be any typical but non-limiting point value or a range between any two point values, such as 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, and 100 nm.

[0108] In some embodiments, the metal nanoparticles contain at least one of silver, gold, magnesium, and bismuth. These metal materials all have high electronic conductivity and can reduce the overpotential of lithium ions during nucleation. During battery charging and discharging, the metal nanoparticles can also form lithium alloy particles with lithium metal, achieving even higher electronic conductivity together with the metal nanoparticles.

[0109] In some embodiments, the metal nanoparticles include silver nanoparticles. In this case, Ag nanoparticles are better able to reduce the overpotential during lithium-ion nucleation and guide Li... + Uniform transport within the intermediate layer enhances the electrical conductivity between interfaces, guiding Li... + The insertion and extraction of silver nanoparticles reduces the possibility of side reactions between the electrolyte and the negative electrode. Furthermore, during battery charging and discharging, silver nanoparticles can form Ag-Li alloys with lithium metal. Therefore, the introduction of Ag allows the silver nanoparticles and the formed Ag-Li alloy to achieve higher electronic conductivity.

[0110] In some embodiments, the conductive binder contains 5% to 20% by mass of conductive carbon material and 5% to 20% by mass of metal nanoparticles. In this case, the content of conductive carbon material and metal nanoparticles sufficiently ensures an increase in the electronic conductivity and ion diffusion coefficient of the negative electrode, and the formed three-dimensional conductive network effectively mitigates the volume expansion and contraction of silicon-based and other negative electrode materials during cyclic charging and discharging. Exemplarily, the mass percentage of conductive carbon material in the conductive binder can be any typical but non-limiting value or a range between any two values, such as 5%, 8%, 10%, 13%, 15%, 18%, or 20%; the mass percentage of metal nanoparticles can be any typical but non-limiting value or a range between any two values, such as 5%, 8%, 10%, 13%, 15%, 18%, or 20%.

[0111] In some embodiments, the conductive binder comprises a polymer having rigid acrylic acid segments and flexible polyethylene glycol methacrylate segments, within which single-walled carbon nanotubes are chemically bonded and silver nanoparticles are grown in situ. The combination of the rigid acrylic acid segments (AA) and the flexible polyethylene glycol methacrylate segments (PEGMA) exhibits excellent mechanical strength and elasticity. The volume expansion caused by lithiation of the anode material, such as silicon-based particles, generates approximately 14% tensile strain in the single-walled carbon nanotubes, which in turn strengthens the chemical interaction between Li and C. This chemical-mechanical coupling effect promotes the transformation of sp2-C to sp3 hybridized Li-C bonds at defects in the single-walled carbon nanotubes, which also triggers the formation of new Si-C chemical bonds at the interface. During this process, the single-walled carbon nanotubes can also induce in-situ reconstruction of the three-dimensional structure of the anode material, forming a mechanically reinforced network with high electrical and ionic conductivity. Furthermore, the conductive binder of this application embodiment can improve the stability of the anode in ambient air, enabling the anode to be prepared in ambient air via thin-film casting, which is beneficial for scale-up fabrication and provides better compatibility with industrial lithium-ion battery production lines.

[0112] In some embodiments, the conductive binder comprises 2% to 20% by mass in the active layer of the negative electrode. In this case, the amount of conductive binder can significantly improve the electronic and ionic conductivity of the negative electrode, while effectively mitigating the volume expansion and contraction stress of silicon-based and other negative electrode materials during cyclic charging and discharging.

[0113] In some embodiments, the negative electrode includes a negative electrode current collector and a negative electrode active layer disposed on at least one surface of the negative electrode current collector. As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode main material is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0114] In some embodiments, the negative electrode active layer comprises a negative electrode substrate and the aforementioned conductive binder. The negative electrode substrate may be a known material for use in battery cells.

[0115] In some embodiments, the negative electrode material includes: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. As an example, the silicon-based material may be selected from at least one of nano-silicon, submicron silicon, micron silicon, silicon-carbon, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxides, and tin alloys.

[0116] In some embodiments, the negative electrode material includes at least one silicon-based material selected from nano-silicon, submicron silicon, micron silicon, silicon-carbon, and silicon alloy. The conductive binder in this application embodiment can significantly improve the electronic and ionic conductivity of the silicon-based negative electrode, while effectively mitigating the volume expansion and contraction stress of the silicon-based negative electrode material during cyclic charging and discharging.

[0117] In some embodiments, the mass content of the negative electrode main material in the negative electrode active layer may be, but is not limited to, 85% to 98%, and may be selected as 95% to 98%. In exemplary cases, it may be a typical but non-limiting content such as 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or any range between two content values.

[0118] In some embodiments, the negative electrode active layer of the negative electrode may also include other binders. Exemplary examples include at least one selected from styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0119] In some embodiments, the negative electrode current collector can be a metal foil, a foamed metal, or a composite current collector. For example, the metal foil can be silver-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium, etc. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc. In an exemplary embodiment, the composite current collector can include a composite material of a polymer and a metal, wherein the polymer can include, but is not limited to, polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc., and the metal can include, but is not limited to, elemental lithium (or elemental sodium), lithium alloy (or sodium alloy), copper, copper alloy, iron, iron alloy, tin, tin alloy, titanium, titanium alloy, silver, silver alloy. The composite current collector can be obtained by mixing polymer and metal, or the metal can be bonded to at least one side of the polymer matrix by electroplating, coating, or other methods.

[0120] In some embodiments, the negative electrode active layer of the negative electrode may optionally include a conductive agent. For example, the conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0121] In some embodiments, the negative electrode active layer of the negative electrode may optionally include other additives, such as dispersants, thickeners (e.g., sodium carboxymethyl cellulose), etc.

[0122] In some embodiments, the positive electrode includes a positive current collector, and a positive active layer is stacked on at least one surface of the positive current collector. In some embodiments, the positive active layer includes a positive electrode material, an electrolyte, and components such as a conductive agent and a binder.

[0123] In some possible implementations, the cathode material in the positive electrode active layer includes at least one of lithium nickel cobalt manganese oxide ternary cathode material, lithium nickel cobalt manganese aluminum quaternary cathode material, lithium-rich manganese-based cathode material, lithium iron phosphate, lithium manganese phosphate, lithium iron manganese phosphate, lithium manganese oxide, or nickel manganese oxide. These lithium-ion cathode materials have high specific capacity or high structural stability and good cycle performance.

[0124] In some embodiments, the mass content of the positive electrode main material contained in the positive electrode active layer of the above-mentioned positive electrode can be 90% to 98%, optionally 92% to 96%. In exemplary examples, it can be a typical but non-limiting content such as 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or any range between two content values. The positive electrode main material within this content range can effectively improve the energy density of the positive electrode.

[0125] In some possible implementations, the positive electrode active layer may further include a conductive agent and a binder. The binder enhances the mechanical properties between the positive electrode active layer itself and the current collector. The conductive agent effectively improves the conductivity of the positive electrode. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), polyethylene (PE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins. The conductive agent includes at least one of conductive carbon black (SP), carbon nanotubes (CNT), carbon fiber (VGCF), Ketjen black (ECP), or graphene.

[0126] In some possible implementations, the electrolyte in the positive electrode active layer can be at least one of the following: sulfide Li6PS5Cl, or binary compounds such as Li2S-GeS2, Li2S-SiS2, Li2S-P2S5, or ternary compounds such as Li2S-MeS2-P2S5 (Me = Si, Ge, Sn, Al, etc.).

[0127] In some possible implementations, the positive electrode current collector can be a metal foil, a foamed metal, or a composite current collector. For example, the metal foil can be silver-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium, etc. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloys, or foamed carbon, etc. The composite current collector can include a polymeric material base layer and a metal layer. The composite current collector can be formed by forming metallic materials such as copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys on a polymeric material substrate such as polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, or polyethylene.

[0128] In some possible implementations, the positive current collector can be made of aluminum foil, and the negative current collector can be made of copper foil.

[0129] In some possible embodiments, the solid electrolyte layer disposed between the positive and negative electrodes comprises a solid electrolyte and a binder. In some embodiments, the mass ratio of the solid electrolyte to the binder may be 100:(1-2). Exemplarily, the solid electrolyte may include at least one of polymer solid electrolytes, oxide electrolytes, sulfide electrolytes, borohydride electrolytes, composite solid electrolytes, etc. In some embodiments, the solid electrolyte includes at least one of Li6PS5Cl, or binary compounds such as Li2S-GeS2, Li2S-SiS2, Li2S-P2S5, or ternary compounds such as Li2S-MeS2-P2S5 (Me = Si, Ge, Sn, Al, etc.). Exemplarily, the binder may be at least one of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), or polyethylene (PE).

[0130] In some possible implementations, the electrode assembly included in the solid-state battery cell 10 typically comprises a positive electrode, a negative electrode, and a solid electrolyte layer. The positive and negative electrodes are alternately stacked, and the solid electrolyte layer is stacked between the positive and negative electrodes to provide insulation, separating the positive and negative electrodes. The electrode assembly containing the solid electrolyte layer is placed in an outer package, and then encapsulated to obtain the solid-state battery cell 10.

[0131] In this embodiment, the solid-state battery cell 10 can be a rechargeable solid-state battery cell 10. A rechargeable battery refers to a solid-state battery cell 10 that can be recharged to activate the electrode active material and continue to be used after it has been discharged. The solid-state battery cell 10 can be a lithium-ion battery, a sodium lithium-ion battery, a lithium metal battery, a lithium-sulfur battery, etc., and this embodiment is not limited to this type.

[0132] In this embodiment, the solid-state battery cell 10 may include a battery casing and an electrode assembly encapsulated within the battery casing. The shape of the solid-state battery cell 10 is not particularly limited; it can be cylindrical, square, or any other arbitrary shape. Figure 1 shows a square-structured solid-state battery cell 10.

[0133] In some possible implementations, as shown in FIG2, the outer packaging of the solid-state battery cell 10 may include a housing 11 and a top cover assembly 12. The housing 11 may include a bottom plate and side plates connected to the bottom plate, the bottom plate and side plates enclosing a receiving cavity. The housing 11 has an opening communicating with the receiving cavity, and the top cover assembly 12 is used to cover the opening to close the receiving cavity. In the embodiments of this application, the positive electrode, solid electrolyte layer and negative electrode contained in the solid-state battery cell 10 may be formed into an electrode assembly 13 by a stacking process. The electrode assembly 13 is encapsulated in the receiving cavity. The number of electrode assemblies 13 contained in the solid-state battery cell 10 may be one or more, which can be adjusted according to actual needs.

[0134] Preparation method of solid-state battery cell 10

[0135] Secondly, embodiments of this application provide a method for preparing a solid-state battery cell 10, comprising the following steps:

[0136] S10. Prepare a conductive binder, the conductive binder comprising a polymer having flexible and rigid segments, and conductive carbon materials and metal nanoparticles bonded to the polymer;

[0137] S20. Prepare a negative electrode containing a conductive binder;

[0138] S30. Provide a positive electrode and a solid electrolyte, and assemble the positive electrode, solid electrolyte and negative electrode to obtain a solid battery cell 10.

[0139] The method for preparing the solid-state battery cell 10 in this application includes a conductive binder comprising a polymer with flexible and rigid chain segments, and conductive carbon materials and metal nanoparticles bonded to the polymer. When applied to the negative electrode, this conductive binder forms a three-dimensional continuous conductive network structure on the surface of silicon-based or other negative electrode materials. This promotes uniform ion and electron transport, improves electron conductivity and ion diffusion coefficient, and effectively mitigates volume deformation of the negative electrode material during charging and discharging. This not only improves the cycle stability of the prepared solid-state battery cell 10, but also increases ionic conductivity, meaning ions can move rapidly within the electrode material, thereby accelerating the battery's charging and discharging speed. Furthermore, higher ionic conductivity results in higher battery power density, thus increasing the battery's energy density and enabling it to store more energy. Additionally, high ionic conductivity helps reduce internal resistance and heat generation during charging and discharging, thereby reducing battery aging and extending battery life. Furthermore, increased electronic conductivity means that electrons can travel rapidly within the electrode material, thereby improving signal transmission speed and response time. This helps reduce electron transport resistance within the battery, thus lowering internal resistance and improving battery efficiency. Higher electronic conductivity results in greater energy density, allowing the battery to store more energy within the same volume or weight.

[0140] In step S10 above:

[0141] In some embodiments, the preparation steps of the conductive adhesive include:

[0142] S11. A polymer is prepared by free radical polymerization of monomers containing flexible segments and monomers containing rigid segments;

[0143] S12. A condensation reaction is carried out between a conductive carbon material grafted with an oxygen-containing group and a polymer, so that the conductive carbon material is chemically bonded to the polymer to obtain an intermediate product.

[0144] S13. After mixing the intermediate product with the metal salt, the metal salt undergoes a self-decomposition reaction, generating metal nanoparticles in situ within the intermediate product to obtain a conductive binder.

[0145] In this application, a polymer is prepared by free radical polymerization of monomers containing flexible and rigid segments. This polymer is then condensed with a conductive carbon material grafted with oxygen-containing groups, chemically bonding the conductive carbon material to the polymer to form a three-dimensional conductive network structure. After mixing with a metal salt, the metal salt undergoes a self-destruction reaction, generating metal nanoparticles in situ within the intermediate product. These metal nanoparticles are then uniformly distributed within the three-dimensional conductive network structure of the polymer and the conductive carbon material, resulting in an ionic / electron dual-conductive binder. Furthermore, its three-dimensional conductive network structure can accommodate the volume deformation of the negative electrode material during charge and discharge processes.

[0146] In step S11 above:

[0147] In some embodiments, the monomer containing flexible segments includes at least one of polyethylene glycol methacrylate monomer, polyethylene monomer, polypropylene monomer, polyester monomer, polyamide monomer, polydimethylsiloxane monomer, and polyurethane monomer.

[0148] In some embodiments, the monomer containing rigid segments includes at least one of acrylic acid monomers, dimethylaminoethyl methacrylate monomers, polyacetylene monomers, polyisocyanate monomers, and polyarylamide monomers.

[0149] In some embodiments, the mass ratio of monomers containing flexible segments to monomers containing rigid segments is (2-3):1. This mass ratio ensures that the polymer exhibits both flexibility and rigidity, giving the conductive adhesive excellent mechanical strength and elasticity.

[0150] In some embodiments, the temperature conditions for the free radical polymerization reaction are 50°C to 80°C, and the reaction time is 2h to 5h; under these conditions, flexible segments and rigid segments undergo free radical polymerization to generate copolymers, i.e., polymers.

[0151] In some embodiments, the free radical polymerization reaction is carried out under the action of an initiator, which includes at least one of ammonium persulfate, potassium persulfate, ammonium persulfate / sodium bisulfite, potassium persulfate / sodium bisulfite, potassium persulfate / silver nitrate, persulfate / thiol, cumene hydroperoxide / ferrous chloride, potassium persulfate / ferrous chloride, and hydroperoxide / ferrous chloride; all of these initiators are capable of initiating free radical polymerization reactions between flexible and rigid segments. Among them, ammonium persulfate / sodium bisulfite means that ammonium persulfate and sodium bisulfite are used together as initiators. Similarly, potassium persulfate / sodium bisulfite means that potassium persulfate and sodium bisulfite are used together as initiators; potassium persulfate / silver nitrate means that potassium persulfate and silver nitrate are used together as initiators; persulfate / thiol means that persulfate and thiol are used together as initiators; cumene hydrogen peroxide / ferrous chloride means that cumene hydrogen peroxide and ferrous chloride are used together as initiators; potassium persulfate / ferrous chloride means that potassium persulfate and ferrous chloride are used together as initiators; hydrogen peroxide / ferrous chloride means that hydrogen peroxide and ferrous chloride are used together as initiators.

[0152] In some embodiments, the polymer includes rigid segments of acrylic acid and soft segments of polyethylene glycol methacrylate. The resulting polymer contains ester groups, amino groups, and ether bonds. These functional groups hardly undergo side reactions with electrolytes such as sulfides, which can significantly improve the stability of systems such as sulfide all-solid-state batteries.

[0153] In step S12 above:

[0154] In some embodiments, the condensation reaction conditions include reacting at a temperature of 65°C to 75°C for 1 to 3 hours. Under these conditions, the oxygen-containing groups grafted onto the surface of the conductive carbon material undergo a condensation reaction with the polymer, causing the conductive carbon material to chemically bond to the polymer, yielding an intermediate product. Exemplarily, the temperature of the condensation reaction can be any typical but non-limiting value, such as 65°C, 68°C, 70°C, 72°C, or 75°C, or a range between any two values; the reaction time can be any typical but non-limiting value, such as 1 hour, 2 hours, or 3 hours, or a range between any two values.

[0155] In some embodiments, the conductive carbon material grafted with oxygen-containing groups includes single-walled carbon nanotubes with hydroxyl and / or carboxyl groups grafted onto their surface. In this case, the hydroxyl and / or carboxyl groups grafted onto the surface of the single-walled carbon nanotubes can undergo a condensation reaction with the hydroxyl or carboxyl groups on the surface of the polymer framework, resulting in a bond between the single-walled carbon nanotubes and the polymer via ester groups, which provides high stability.

[0156] In step S13 above:

[0157] In some embodiments, the conditions for the self-decomposition reaction include: stirring and mixing for 3 to 5 hours, followed by reaction at a temperature of 70°C to 80°C for 6 to 10 hours. Under these reaction conditions, the metal salt is in situ generated into elemental metal nanoparticles within the three-dimensional conductive network structure of the polymer and conductive carbon material, uniformly loaded within the three-dimensional conductive network structure, thereby improving the electronic conductivity of the negative electrode.

[0158] In some embodiments, the solvents used in the self-decomposition reaction include at least one of N,N-dimethylformamide, dimethylacetamide (DMAC), dimethylpropionamide (DMP), diethylformamide (DEF), and diethylacetamide (DEAC); these solvents have good solubility and dispersion effects on the three-dimensional conductive network structure of metal salts, intermediate polymers, and conductive carbon materials.

[0159] In some embodiments, the metal salt includes at least one of silver, gold, magnesium, and bismuth salts. The metal nanoparticles generated in situ from these metal salts all exhibit high electronic conductivity.

[0160] In some embodiments, the metal salt includes silver salt, which includes silver nitrate, silver carbonate, silver sulfate, etc.

[0161] In some embodiments, the metal nanoparticles include silver nanoparticles. In this case, Ag nanoparticles are better able to reduce the overpotential during lithium-ion nucleation and guide Li... + Uniform transport within the intermediate layer enhances the electrical conductivity between interfaces, guiding Li... +The insertion and extraction of silver nanoparticles reduces the possibility of side reactions between the electrolyte and the negative electrode. Furthermore, during battery charging and discharging, silver nanoparticles can form Ag-Li alloys with lithium metal. Therefore, the introduction of Ag allows the silver nanoparticles and the formed Ag-Li alloy to achieve higher electronic conductivity.

[0162] In some embodiments, silver nitrate (AgNO3) has high solubility in DMF (N,N-dimethylformamide) and a slight tendency to form complexes due to the high polarity of DMF. At room temperature, the solution may turn yellow when silver nitrate is mixed with DMF, typically due to the reduction of silver nitrate to silver nanoparticles. Heating under reflux accelerates the reduction reaction, making the formation of silver nanoparticles more efficient.

[0163] In some embodiments, the mass ratio of conductive carbon material, metal nanoparticles, and polymer in the conductive binder is (5–20):(5–20):(60–90). In this case, the content of conductive carbon material and metal nanoparticles sufficiently ensures the improvement of electronic conductivity and ion diffusion coefficient in the negative electrode, and the formed three-dimensional conductive network can effectively alleviate the volume expansion and contraction of silicon-based and other negative electrode materials during cyclic charging and discharging. Exemplarily, the mass ratio of conductive carbon material, metal nanoparticles, and polymer can be any typical but non-limiting point value or a range between any two points, such as 5:5:90, 10:10:80, 15:15:70, or 20:20:60.

[0164] In some embodiments, carboxylated single-walled carbon nanotubes, PAP (PAA-PEGMA), and silver nitrate are used as raw materials. The former two are assembled into a polymeric SMCNTs-COOC-PAP with ionic / electronic dual conductivity through a carboxyl condensation reaction under heating conditions. Ag nanoparticles are then grown in situ in the polymer to obtain Ag@SMCNTs-COOC-PAP, which replaces conductive carbon additives as an ionic / electronic dual conductive binder for use in silicon-based anodes of sulfide solid-state batteries.

[0165] In step S20 above, a negative electrode containing a conductive binder is prepared. In some possible implementations, the negative electrode preparation steps include: making a slurry of the conductive binder and the negative electrode main material into a negative electrode active layer, coating the slurry of the negative electrode active layer onto the surface of the negative electrode current collector, and then performing steps such as drying, rolling, and die-cutting.

[0166] In step S30 above, a positive electrode and a solid electrolyte are provided, and the positive electrode, solid electrolyte and negative electrode are assembled to obtain a solid battery cell 10.

[0167] In some possible implementations, the preparation steps of the positive electrode include: after preparing a slurry for the positive electrode active layer, coating the slurry for the positive electrode active layer onto the surface of the positive electrode current collector, and then performing steps such as drying, rolling, and die cutting.

[0168] In some possible implementations, a positive electrode, a solid electrolyte, and a negative electrode can be stacked to form a solid-state battery cell 10. As an example, a positive electrode, a solid electrolyte, and a negative electrode can be stacked to form an electrode assembly 13. The electrode assembly 13 is placed in an outer packaging, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping processes, a solid-state battery cell 10 is obtained.

[0169] In this application embodiment, the solid-state battery cell 10 refers to a solid-state battery assembly including a battery casing and a solid-state battery cell encapsulated within the battery casing. The shape of the solid-state battery cell 10 is not particularly limited; it can be cylindrical, square, or any other arbitrary shape. In the exemplary example, the solid-state battery cell 10 can be a square-structured solid-state battery cell 10 as shown in FIG1.

[0170] Battery device

[0171] Thirdly, embodiments of this application provide a battery device, including a solid-state battery cell 10 provided in the first aspect of embodiments of this application or a solid-state battery cell 10 prepared by the preparation method provided in the second aspect of embodiments of this application.

[0172] The battery device provided in this application embodiment is based on the solid-state battery cell 10 of this application embodiment. Therefore, the battery device of this application embodiment has a good cycle life under the premise of high energy density.

[0173] The battery apparatus mentioned in the embodiments of this application may include one or more solid-state battery cells 10 for providing voltage and capacity. The solid-state battery cell assembly may include multiple solid-state battery cells 10, which are connected in series, parallel, or mixed connection via a busbar.

[0174] In some embodiments, the battery device of this application may include any one of a solid-state battery cell 10, a battery module, or a battery pack.

[0175] A battery module is assembled from the solid-state battery cell 10, which means it can contain multiple solid-state battery cells 10. The specific number can be adjusted according to the application and capacity of the battery module.

[0176] In some embodiments, Figure 3 is a schematic diagram of a battery module 20 as an example. In the battery module 20, a plurality of solid-state battery cells 10 may be arranged sequentially along the length of the battery module 20. Of course, they can also be arranged in any other manner. The plurality of solid-state battery cells 10 can be fixed by fasteners. Optionally, the battery module 20 may also include a housing with a receiving space in which the plurality of solid-state battery cells 10 are received.

[0177] A battery pack refers to an assembly of solid-state battery cells 10, as described above. It can contain multiple solid-state battery cells 10, which can be assembled into a battery module 20. The specific number of solid-state battery cells 10 or battery modules 20 contained in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0178] As shown in the embodiments, Figures 4 and 5 are schematic diagrams of a battery pack 30 as an example. The battery pack 30 may include a battery box and multiple battery modules 20 disposed within the battery box. The battery box includes an upper box 31 and a lower box 32, the upper box 31 covering the lower box 32 and forming a closed space for accommodating the battery modules 20. The multiple battery modules 20 can be arranged in any manner within the battery box.

[0179] Electrical appliances

[0180] Fourthly, embodiments of this application provide an electrical device, including a solid-state battery cell 10 provided in the first aspect of this application, a solid-state battery cell 10 prepared by the preparation method provided in the second aspect of this application, or a battery device provided in the third aspect of this application.

[0181] The electrical device provided in this application embodiment is based on the solid-state battery cell 10 or battery device of this application embodiment, therefore the electrical device of this application embodiment can work safely and for a long time.

[0182] In some implementations, the electrical device may be, but is not limited to, mobile devices (e.g., mobile phones, portable devices, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, electric vehicles, electric toys, power tools, etc.), electric trains, ships, satellites and spacecraft, energy storage systems, etc. The electrical device may be configured with sub-solid-state battery cells 10, battery modules, or battery packs according to its usage requirements.

[0183] Figure 6 shows a schematic diagram of an example electrical device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the device's requirements for high power and high energy density, a battery pack or battery module can be used.

[0184] Another example of an electrical device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use rechargeable batteries as their power source.

[0185] Energy storage devices

[0186] Fifthly, embodiments of this application provide an energy storage device, including a solid-state battery cell 10 provided in the first aspect of embodiments of this application, a solid-state battery cell 10 prepared by the preparation method provided in the second aspect of embodiments of this application, or a battery device provided in the third aspect of embodiments of this application.

[0187] Since the energy storage device in this application embodiment contains the solid-state battery cell 10 or battery device described in the above application embodiment, the energy storage device has high energy density, good cycle performance, and long service life.

[0188] In some embodiments, the energy storage device includes one or more battery clusters to increase the voltage and capacity of the energy storage device. A battery cluster may include multiple battery units connected in series via a busbar to increase the voltage of the energy storage device. When the energy storage device includes multiple battery clusters, the battery clusters are connected in parallel to increase the capacity of the energy storage device.

[0189] In some implementations, energy storage devices can be used in energy storage power stations, wind power generation systems, solar power generation systems, mobile power systems, or temporary power supply systems. Energy storage devices can store electrical energy as needed and output it when appropriate. For example, an energy storage device can store electrical energy during off-peak hours and provide power to relevant users or electrical equipment during peak hours. The energy storage system provided in this application embodiment can be any power system that requires energy storage devices.

[0190] In some implementations, the energy storage device is an energy storage container or an energy storage cabinet.

[0191] In some implementations, the energy storage device may include a cabinet and one or more battery clusters housed within the cabinet.

[0192] In some implementations, the energy storage device may include modules such as a thermal management module, a main control module, a central control module, a power distribution module, and a fire protection module.

[0193] In a sixth aspect, this application provides a conductive adhesive comprising a polymer having flexible and rigid segments, and conductive carbon materials and metal nanoparticles bonded to the polymer.

[0194] In the embodiments of this application, the polymer, conductive carbon material, and metal nanoparticles in the conductive binder form a three-dimensional conductive network structure, which can form a three-dimensional continuous conductive network structure on the surface of the electrode material. This can not only promote the uniform transport of ions and electrons and provide conductivity by electrons and ions, but also effectively alleviate the volume deformation of the electrode material during charging and discharging.

[0195] The conductive binder of this application is particularly suitable for the silicon-based negative electrode of solid-state batteries, which has large volumetric deformation.

[0196] In some embodiments, the polymer includes rigid segments of acrylic acid and soft segments of polyethylene glycol methacrylate.

[0197] In some embodiments, the conductive carbon material includes single-walled carbon nanotubes.

[0198] In some embodiments, the particle size Dv50 of the metal nanoparticles is 20 nm to 100 nm;

[0199] In some embodiments, the metal in the metal nanoparticles includes at least one metal selected from silver, gold, magnesium, and bismuth.

[0200] In some embodiments, the conductive binder contains 5% to 20% by mass of conductive carbon material and 5% to 20% by mass of metal nanoparticles.

[0201] The technical effects of the conductive adhesive embodiments described above have been discussed in detail above and will not be repeated here.

[0202] Example

[0203] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0204] Example 1

[0205] A solid-state battery cell 10 is prepared by the following steps:

[0206] 1. Preparation of conductive adhesive:

[0207] (1) Synthesis of SMCNTs-COOC-PAP: PAP was synthesized by conventional free radical polymerization, wherein the weight ratio of rigid segment acrylic acid (AA) to flexible segment polyethylene glycol methacrylate (PEGMA) was controlled at 1:2. Specifically, 1.4 g AA, 2.8 g PEGMA, 21 mg ammonium persulfate (APS), and 16.8 g deionized water were added to a 50 mL round-bottom flask equipped with a magnetic stir bar. After degassing (inert gas purging) three times, 0.5 g SWCNT-O was introduced, and the mixture was heated at 70 °C for 1.5 hours. The obtained product was purified by dialyzing in deionized water (7 kDa), followed by freeze-drying to obtain SMCNTs-COOC-PAP.

[0208] (2) Synthesis of Ag@SMCNTs-COOC-PAP: Ag@SMCNTs-COOC-PAP was produced by introducing 2g SMCNTs-COOC-PAP, 3.2g AgNO3 and 20g DMF. The mixture was stirred for 4h and then heated at 75℃ for 8h.

[0209] 2. Preparation of silicon anode sheet: 160 mg Si powder, 40 mg Ag@SMCNTs-COOC-PAP, and 600 mg deionized water were mixed in a 50 mL grinding jar at 350 rpm for 1 hour. A composite Si anode was prepared by coating a copper foil with a slurry containing 80 wt% Si powder and 20 wt% binder. The ball-milled slurry was then coated onto the copper foil, with a wet film thickness of 80 μm and a silicon anode loading of 0.5 mg / cm². 2 The above electrode sheets were placed in a vacuum drying oven and dried at 80°C for 2 hours, then kept at 140°C for 6 hours. The negative electrode sheet was obtained.

[0210] 3. Dry preparation of positive electrode sheet: The positive electrode is prepared by mixing the main positive electrode material NMC (lithium nickel cobalt manganese oxide), the conductive agent VGCF (vapor-grown carbon fiber), and the solid electrolyte sulfide LPSCl (i.e., Li6PS5Cl) in a mass ratio of 70:30:5.

[0211] 4. Preparation of solid electrolyte layer: The electrolyte layer is prepared by mixing sulfide electrolyte LPSCl and binder PTFE (polytetrafluoroethylene) at a ratio of 100:1.

[0212] 5. Battery assembly: Assemble the cells in the order of positive electrode-electrolyte-negative electrode stacking, and obtain a soft-pack battery after high-temperature densification treatment.

[0213] Example 2

[0214] A solid-state battery cell 10 differs from Example 1 in that the rigid chain segment is made of DMAEMA, and Ag@SMCNTs-COOC-DMAEMA-PEGDA is applied to the negative electrode.

[0215] Example 3

[0216] A solid-state battery cell 10 differs from Example 1 in that the flexible segments are made of polypropylene.

[0217] Example 4

[0218] A solid-state battery cell 10 differs from Example 1 in that the ratio of rigid segments to flexible segments is different, using 3:1.

[0219] Examples 5-7

[0220] The solid-state battery cell 10 provided in Examples 5-7 differs from that in Example 1 in that the conductive carbon material in the conductive additive is different, as shown in Table 1 below.

[0221] Examples 8-10

[0222] The solid-state battery cell 10 provided in Examples 8-10 differs from that in Example 1 in that the conductive additive contains different metal nanomaterials, as shown in Table 1 below.

[0223] Examples 11-13

[0224] The solid-state battery cell 10 provided in Examples 11-13 differs from that in Example 1 in that the content of conductive carbon material in the conductive additive is different, as shown in Table 1 below.

[0225] Examples 15-18

[0226] The solid-state battery cell 10 provided in Examples 15-18 differs from that in Example 1 in that the content of metal nanomaterials in the conductive additive is different, as shown in Table 1 below.

[0227] Comparative Example 1

[0228] A solid-state battery cell 10 differs from Example 1 in that the binder in the silicon anode sheet is PEDOT:PSS-PPP.

[0229] Comparative Example 2

[0230] A solid-state battery cell 10 differs from Example 1 in that the binder in the silicon anode sheet is PVDF.

[0231] Comparative Example 3

[0232] A solid-state battery cell 10 differs from Example 1 in that the conductive binder used is SMCNTs-COOC-PAP prepared in step ①, and silver nanoparticles are not grown in situ.

[0233] Comparative Example 4

[0234] A solid-state battery cell 10 differs from Example 1 in that it does not graft SECNTs into the conductive binder. The synthesis steps include: adding 1.4 g AA, 2.8 g PEGMA, 21 mg ammonium persulfate (APS), and 16.8 g deionized water to a 50 mL round-bottom flask equipped with a magnetic stir bar. After degassing (inert gas purging) three times, PAP is obtained. 3.2 g AgNO3 and 20 g DMF are introduced, the mixture is stirred for 4 h, and then heated at 75 °C for 8 h to obtain Ag@PAP.

[0235] Comparative Example 5

[0236] A solid-state battery cell 10 differs from Example 1 in that a polymer is added to the conductive binder. The synthesis step includes: stirring a mixture of 2g SMCNTs-COOOH, 3.2g AgNO3 and 20g DMF for 4h, and then heating at 75°C for 8h to obtain Ag@SMCNTs-COOH.

[0237] Comparative Example 6

[0238] A solid-state battery cell 10 differs from Example 1 in that the conductive carbon material and metal nanoparticles in the conductive binder are not grafted onto the polymer, but only physically mixed. The steps include: adding 1.4g AA, 2.8g PEGMA, 21mg ammonium persulfate (APS), and 16.8g deionized water to a 50mL round-bottom flask equipped with a magnetic stir bar, degassing (purging with inert gas) three times to obtain PAP. The obtained PAP is then mixed with 0.5g SWCNT-O and 50nm silver nanoparticles to obtain an Ag-SMCNTs-PAP mixture.

[0239] The substances used in the above embodiments and comparative examples are shown in Table 1 below:

[0240] Table 1

[0241] Performance testing:

[0242] The following performance tests were performed on the above embodiments and comparative examples:

[0243] 1. First-cycle discharge capacity (mAh / g) test conditions: 60℃, loading pressure 50MPa, 0.1C charging, 0.1C discharging;

[0244] 2. First-cycle coulombic efficiency (%) test conditions: 60℃, loading pressure 50MPa, 0.1C charging, 0.1C discharging;

[0245] 3. 2C discharge capacity (mAh / g) test conditions: 60℃, loading pressure 50MPa, 0.1C charging, 0.2C discharging;

[0246] 4. Capacity retention rate (%) after 100 cycles: 60℃, loading pressure 50MPa, 0.33C charging, 0.33C discharging, 100 cycles;

[0247] The test results are shown in Table 2 below:

[0248] Table 2

[0249] The test results above show that the conductive binder in the solid-state battery cell of this application includes polymers with flexible and rigid segments. The polymer formed by the reasonable combination of flexible and rigid segments gives the conductive binder excellent mechanical strength and elasticity, effectively suppressing the volume expansion of anode materials such as silicon and improving the cycle stability of the solid-state battery cell. Furthermore, the polymer, its functional groups, and the conductive carbon materials and metal nanoparticles bonded within the polymer form a three-dimensional conductive network structure, creating a lithium-ion conductive pathway and increasing the lithium-ion conductivity of the binder. The silver nanoparticles, together with the formed Ag-Li alloy, achieve high electronic conductivity. This not only promotes uniform ion and electron transport, improves electronic conductivity and ion diffusion coefficient, and enhances the initial coulombic efficiency, but also effectively mitigates the volume deformation of the anode material during charging and discharging.

[0250] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A solid-state battery cell, comprising a positive electrode and a negative electrode, and a solid electrolyte layer disposed between the positive electrode and the negative electrode, wherein, The negative electrode contains a conductive binder, which includes a polymer having flexible and rigid segments, as well as conductive carbon materials and metal nanoparticles bonded to the polymer.

2. The solid-state battery cell as described in claim 1, wherein, The polymer has at least one of the following characteristics (1) to (5): (1) The flexible segment includes at least one of polyethylene glycol methacrylate, polyethylene, polypropylene, polyester, polyamide, polydimethylsiloxane, and polyurethane; (2) The rigid segment includes at least one of acrylic acid, dimethylaminoethyl methacrylate, polyacetylene, polyisocyanate, and polyarylamide; (3) The mass ratio of the flexible chain segment to the rigid chain segment is (2-3):1; (4) The polymer contains at least one functional group selected from ester, amino, and ether bonds; (5) The weight-average molecular weight of the polymer is 10,000 to 70,000.

3. The solid-state battery cell as described in claim 2, wherein, The polymer comprises rigid segments of acrylic acid and soft segments of polyethylene glycol methacrylate; And / or, the tensile strength of the polymer is 200 kPa to 1 MPa; And / or, the elastic modulus of the polymer is 300 kPa to 500 kPa.

4. The solid-state battery cell according to any one of claims 1 to 3, wherein, The conductive carbon material is bonded to the polymer via chemical bonding. And / or, the conductive carbon material includes at least one of single-walled carbon nanotubes, carbon black, carbon fiber, and multi-walled carbon nanotubes.

5. The solid-state battery cell as described in claim 4, wherein, The conductive carbon material includes single-walled carbon nanotubes; And / or, the average outer diameter of the single-walled carbon nanotube is 1 nm to 2 nm, the length is not less than 5 μm, and the aspect ratio is 2000 to 10000; And / or, the bonding between the single-walled carbon nanotubes and the polymer includes ester bonding.

6. The solid-state battery cell according to any one of claims 1 to 5, wherein, The particle size Dv50 of the metal nanoparticles is 20nm to 100nm; And / or, the metal in the metal nanoparticles includes at least one of silver, gold, magnesium, and bismuth.

7. The solid-state battery cell as described in claim 6, wherein, The metal nanoparticles include silver nanoparticles.

8. The solid-state battery cell according to any one of claims 1 to 7, wherein, In the conductive binder, the mass percentage of the conductive carbon material is 5% to 20%, and the mass percentage of the metal nanoparticles is 5% to 20%. And / or, the conductive binder has a mass percentage content of 2% to 20% in the active layer of the negative electrode; And / or, the negative electrode material in the negative electrode includes silicon-based materials; And / or, the solid electrolyte layer includes a sulfide solid electrolyte.

9. A method for preparing a single battery cell, wherein, Includes the following steps: A conductive binder is prepared, the conductive binder comprising a polymer having flexible and rigid segments, and conductive carbon materials and metal nanoparticles bonded to the polymer; Prepare a negative electrode containing the conductive binder; A positive electrode and a solid electrolyte are provided, and the positive electrode, the solid electrolyte and the negative electrode are assembled to obtain a battery cell.

10. The method for preparing a battery cell as described in claim 9, wherein, The preparation steps of the conductive adhesive include: The polymer is prepared by free radical polymerization of monomers containing flexible segments and monomers containing rigid segments. A conductive carbon material grafted with oxygen-containing groups is subjected to a condensation reaction with the polymer to chemically bond the conductive carbon material to the polymer, thereby obtaining an intermediate product. After the intermediate product is mixed with a metal salt, the metal salt undergoes a self-decomposition reaction, generating the metal nanoparticles in situ within the intermediate product, thus obtaining the conductive binder.

11. The method for preparing a battery cell as described in claim 10, wherein, The free radical polymerization reaction is carried out at a temperature of 50℃ to 80℃ and for a reaction time of 2h to 5h. And / or, the conditions for the condensation reaction include: reacting at a temperature of 65°C to 75°C for 1 to 3 hours; And / or, the conditions for the self-decomposition reaction include: stirring and mixing for 3 to 5 hours, followed by reaction at a temperature of 70°C to 80°C for 6 to 10 hours.

12. The method for preparing a battery cell as described in claim 10 or 11, wherein, The mass ratio of the monomer containing flexible segments to the monomer containing rigid segments is (2-3):1; And / or, in the conductive binder, the mass ratio of the conductive carbon material, the metal nanoparticles and the polymer is (5-20):(5-20):(60-90).

13. The method for preparing a battery cell according to any one of claims 10 to 12, wherein, The free radical polymerization reaction is carried out under the action of an initiator, which includes at least one of ammonium persulfate, potassium persulfate, ammonium persulfate / sodium bisulfite, potassium persulfate / sodium bisulfite, potassium persulfate / silver nitrate, persulfate / thiol, cumene hydroperoxide / ferrous chloride, potassium persulfate / ferrous chloride, and hydroperoxide / ferrous chloride. And / or, the solvent used in the self-decomposition reaction includes at least one of N,N-dimethylformamide, dimethylacetamide, dimethylpropionamide, diethylformamide, and diethylacetamide; And / or, the metal salt includes at least one of silver salt, gold salt, magnesium salt, and bismuth salt.

14. The method for preparing a battery cell according to any one of claims 10 to 13, wherein, The polymer comprises rigid segments of acrylic acid and soft segments of polyethylene glycol methacrylate; And / or, the conductive carbon material grafted with oxygen-containing groups includes single-walled carbon nanotubes with hydroxyl and / or carboxyl groups grafted onto their surface. And / or, the metal nanoparticles include silver nanoparticles.

15. A battery device, wherein, Includes solid-state battery cells as described in any one of claims 1 to 8 or solid-state battery cells prepared by the preparation methods described in claims 9 to 14.

16. An electrical appliance, wherein, Includes solid-state battery cells as described in any one of claims 1 to 8, solid-state battery cells prepared by the preparation methods described in claims 9 to 14, or battery devices as described in claim 15.

17. An energy storage device, wherein, Includes solid-state battery cells as described in any one of claims 1 to 8, solid-state battery cells prepared by the preparation methods described in claims 9 to 14, or battery devices as described in claim 15.

18. A conductive adhesive, wherein, The conductive binder comprises a polymer having flexible and rigid segments, and conductive carbon materials and metal nanoparticles bonded to the polymer.

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