Solid-state battery cell and method of making and use thereof

Abstract

The application relates to the technical field of batteries, in particular to a solid-state battery monomer and a preparation method and application thereof. The solid-state battery monomer comprises a positive electrode, a solid-state electrolyte and a negative electrode current collector which are sequentially arranged in layers, an interface layer is arranged between the solid-state electrolyte and the negative electrode current collector, the interface layer comprises carbon nanomaterial and metal nanoparticles anchored on the surface of the carbon nanomaterial. In the solid-state battery monomer, the interface layer arranged between the solid-state electrolyte and the negative electrode current collector can significantly improve the uniformity and efficiency of lithium ion transmission between the solid-state electrolyte and the negative electrode current collector through the joint action of the carbon nanomaterial and the metal nanoparticles anchored thereon, can induce uniform deposition of lithium metal on the side of the negative electrode current collector, can inhibit the formation of dendrites, can reduce the interface side reaction, and can improve the electrochemical performance such as coulomb efficiency, cycle stability and safety of the solid-state battery.

Description

Technical Field

[0001] This application belongs to the field of battery technology, specifically relating to a solid-state battery cell, its preparation method, and its application. Background Technology

[0002] Lithium-ion batteries, with their high energy density and good cycle stability, are among the most widely used energy storage systems. Compared to liquid lithium-ion batteries, all-solid-state battery systems using metallic lithium as the negative electrode offer higher energy density and safety. However, all-solid-state lithium batteries suffer from poor solid-solid interface kinetics, resulting in uneven lithium-ion deposition on the negative electrode side. This leads to unavoidable dendrite growth and interfacial side reactions. Furthermore, the significant volume expansion during charge and discharge processes causes irreversible capacity decay, significantly hindering the practical application of all-solid-state lithium batteries. Summary of the Invention

[0003] In view of the above problems, this application provides a solid-state battery cell, its preparation method and application, to solve the technical problem of uneven lithium ion deposition on the negative electrode side in existing solid-state batteries, which leads to dendrite growth and interfacial side reactions.

[0004] In a first aspect, this application provides a solid-state battery cell, comprising a positive electrode, a solid electrolyte, and a negative electrode current collector stacked sequentially, wherein an interface layer is provided between the solid electrolyte and the negative electrode current collector, and the interface layer comprises carbon nanomaterials and metal nanoparticles anchored on the surface of the carbon nanomaterials.

[0005] The solid-state battery cell provided in this application has an interface layer between the negative electrode current collector and the solid electrolyte layer. This interface layer includes carbon nanomaterials and metal nanoparticles anchored on the surface of the carbon nanomaterials. The carbon nanomaterials possess high electronic / ionic conductivity and exhibit low volume expansion during lithiation. The lithium metal remaining on the surface of the carbon nanomaterials after lithiation can also induce interfacial reactions, forming excellent ion and electron transport channels. Therefore, it can promote efficient lithium-ion transport at the interface between the negative electrode current collector and the solid electrolyte, significantly reducing interfacial resistance. Furthermore, the metal nanoparticles anchored in the carbon nanomaterials do not migrate during charge-discharge cycles due to lithium-ion insertion / extraction, resulting in good material structural stability. The metal nanomaterials can form an alloy with lithium metal. This alloy forms a solid solution in the solid-solid interface gap between the solid electrolyte and the negative electrode current collector. Through the action of pressure and interfacial adhesion, it modifies the interfacial gaps, better guiding the uniform transport of lithium ions within the intermediate layer, improving the uniformity of lithium-ion transport and deposition, and inducing uniform deposition of lithium metal on the negative electrode current collector side. Furthermore, the modified metal nanoparticles can largely prevent direct contact between the solid electrolyte material and the carbon nanoparticles, thereby reducing interfacial side reactions and contributing positively to the initial coulombic efficiency of the solid-state battery. In the solid-state battery cell of this application, the interfacial layer between the solid electrolyte and the negative electrode current collector, through the combined action of the carbon nanoparticles and their anchored metal nanoparticles, can significantly improve the uniformity and efficiency of lithium-ion transport between the solid electrolyte and the negative electrode current collector, induce uniform deposition of lithium metal on the negative electrode current collector side, suppress dendrite formation, reduce interfacial side reactions, and improve the electrochemical performance of the solid-state battery, such as coulombic efficiency, cycle stability, and safety.

[0006] In some embodiments, the solid-state battery cell is a negative electrode-free solid-state battery. This application, through an interface layer disposed between the negative electrode current collector and the solid electrolyte, can reduce the loss of effective contact area due to volume changes through interface engineering, and also enable uniform electron distribution. This, in turn, induces uniform deposition of lithium metal on the negative electrode current collector side, regulates lithium ion deposition, suppresses dendrite formation, reduces interfacial side reactions, and prevents battery short circuits.

[0007] In some embodiments, the carbon nanomaterial includes at least one of single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene, and carbon fibers; these carbon nanomaterials all have high electronic / ionic dual conductivity, can form a uniform three-dimensional conductive network in the interface layer, have better chemical stability, promote uniform deposition of lithium ions on the negative electrode side, and reduce interfacial side reactions.

[0008] In some embodiments, the carbon nanomaterial includes single-walled carbon nanotubes; single-walled carbon nanotubes exhibit higher uniformity and stability, and can stabilize solid-solid contacts by utilizing low volume expansion and induced interfacial reactions, promoting efficient transport of lithium ions at the interface and significantly reducing interfacial resistance.

[0009] In some embodiments, the average diameter of the single-walled carbon nanotubes is 1 nm to 3 nm, and the average length is 1 μm to 5 μm. The single-walled carbon nanotubes have a high aspect ratio and strong flexibility, and can form a three-dimensional conductive mesh even with low addition amounts. Their conductivity and ion transport performance are far superior to those of multi-walled carbon nanotubes.

[0010] In some embodiments, the surface of the carbon nanomaterial is grafted with oxygen-containing functional groups. This helps to improve the electrical properties and compatibility of the carbon nanomaterial and reduce interfacial impedance.

[0011] In some embodiments, the oxygen-containing functional group includes at least one selected from hydroxyl, carboxyl, ether, ester, nitro, and aldehyde groups. These oxygen-containing functional groups are all beneficial for improving the compatibility and electrical properties of carbon nanomaterials.

[0012] In some embodiments, the metal nanoparticles contain at least one of silver, gold, copper, magnesium, tungsten, and bismuth; all of which have excellent electron transport properties and can form alloys with lithium metal to modify interfacial gaps, improve the transport and deposition uniformity of lithium ions, and induce uniform deposition of lithium metal on the negative electrode current collector side.

[0013] 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, 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.

[0014] In some embodiments, the connection between the metal nanoparticles and the carbon nanomaterial includes hydrogen bonding. The metal nanoparticles are stably anchored in the carbon nanomaterial through hydrogen bonds, and do not migrate with lithium ion insertion / extraction during charge-discharge cycles, resulting in good material structural stability.

[0015] In some embodiments, the total mass of the carbon nanomaterial and the metal nanoparticles is 100%, and the mass percentage of the metal nanoparticles is 5% to 50%. This not only ensures the bonding stability of the metal-carbon composite material, but also improves the transport and deposition uniformity of lithium ions through the bilayer effect of the carbon nanomaterial and the metal nanoparticles, induces uniform deposition of lithium metal on the negative electrode current collector side, suppresses the formation of dendrites, and reduces interfacial side reactions.

[0016] In some embodiments, the carbon nanomaterial in the interface layer comprises single-walled carbon nanotubes with carboxyl groups grafted onto their surface, and the metal nanoparticles anchored to the surface of the carbon nanomaterial include silver nanoparticles. In this case, the electrochemical performance of solid-state batteries, such as coulombic efficiency, cycle stability, and safety, can be better improved.

[0017] In some embodiments, the interface layer further includes an adhesive to improve the stability of the interface layer.

[0018] In some embodiments, the binder in the interface layer comprises 1% to 10% by mass. This ensures sufficient stability and electrochemical performance of the interface layer.

[0019] In some embodiments, the adhesive includes at least one of polyvinylidene fluoride, nitrile rubber, and polytetrafluoroethylene; these adhesives all have excellent adhesive properties and can effectively bond the metal-carbon composite materials and other components in the interface layer tightly together.

[0020] In some embodiments, the thickness of the interface layer is 10 μm to 15 μm. This is beneficial for the fabrication process and can better improve the uniformity and efficiency of lithium ion transport between the solid electrolyte and the negative electrode current collector, induce uniform deposition of lithium metal on the negative electrode current collector side, suppress the formation of dendrites, and reduce interfacial side reactions.

[0021] Secondly, this application provides a method for preparing a solid-state battery cell, comprising the following steps:

[0022] Metal nanoparticles are anchored in carbon nanomaterials to prepare metal-carbon composite materials;

[0023] After the metal-carbon composite material is formed into an interface layer on the surface of the negative electrode current collector, it is assembled with the positive electrode and solid electrolyte to obtain a solid-state battery cell.

[0024] This application discloses a method for preparing solid-state battery cells. A metal-carbon composite material is prepared by anchoring metal nanoparticles within carbon nanomaterials. This composite material is then used as an interface layer on the surface of the negative electrode current collector. Finally, it is assembled with the positive electrode and a solid electrolyte to obtain a solid-state battery cell. The preparation process is simple and suitable for large-scale industrial production and application. In the interface layer between the negative electrode current collector and the solid electrolyte layer, the carbon nanomaterials exhibit low volume expansion during lithiation. The lithium metal remaining on the surface of the carbon nanomaterials after lithiation can also induce interfacial reactions, promoting efficient lithium-ion transport at the interface between the negative electrode current collector and the solid electrolyte, significantly reducing interfacial resistance. The metal nanoparticles anchored in the carbon nanomaterials exhibit good loading stability. The metal nanomaterials can form alloys with lithium metal, modifying the solid-solid interface gap between the solid electrolyte and the negative electrode current collector, better guiding the uniform transport of lithium ions within the intermediate layer, improving the uniformity of lithium-ion transport and deposition, and inducing uniform deposition of lithium metal on the negative electrode current collector side. Therefore, through the action of the interface layer, lithium metal is induced to be deposited uniformly on the negative electrode current collector side, suppressing the formation of dendrites, reducing interfacial side reactions, and improving the electrochemical performance of solid-state batteries, such as coulombic efficiency, cycle stability, and safety.

[0025] In some embodiments, the preparation steps of the metal-carbon composite material include:

[0026] The carbon nanomaterials are subjected to acidification treatment to obtain acidified carbon materials;

[0027] The acidified carbon material is sensitized to obtain a sensitized carbon material;

[0028] The sensitized carbon material is mixed with a metal salt solution for a reduction reaction, and the metal nanoparticles are generated in situ on the surface of the carbon nanomaterial to obtain the metal-carbon composite material.

[0029] In some embodiments, the acidification treatment uses concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 1:(3-5) at a temperature of 60°C to 80°C; or, the acidification treatment uses concentrated nitric acid at a temperature of 110°C to 130°C. In this case, acidification treatment of carbon nanomaterials with strong acids is an effective surface modification method that can significantly improve the dispersibility, stability, and activity of carbon nanomaterials.

[0030] In some embodiments, the sensitization treatment is carried out in a solution with a tin salt concentration of 0.02 mol / L to 0.1 mol / L and a hydrochloric acid concentration of 0.5 mol / L to 0.9 mol / L; in this case, the Sn in the solution... 2+ Tin ions can be uniformly loaded into carbon nanomaterials, and their concentration ensures the sensitization effect on carbon nanomaterials. Hydrochloric acid solution improves the dispersion performance of carbon nanomaterials.

[0031] In some embodiments, the temperature conditions for the mixed reduction reaction are 20°C to 40°C. Under these temperature conditions, sensitized ions such as tin loaded on the surface of the carbon nanomaterial can efficiently reduce metal ions into metal nanoparticles that are anchored in situ to the surface of the carbon nanomaterial.

[0032] In some embodiments, the metal salt solution is an ammoniacal metal nitrate solution. This is more conducive to the reduction of metal ions into metal nanoparticles by sensitizing ions such as tin, allowing the metal nanoparticles to be anchored in situ within the carbon nanomaterial.

[0033] In some embodiments, the metal-carbon composite material has at least one of the following characteristics (1) to (5):

[0034] (1) The carbon nanomaterials include at least one of single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene, and carbon fibers;

[0035] (2) The surface of the carbon nanomaterial is grafted with carboxyl groups;

[0036] (3) The metal nanoparticles contain at least one of the following metal materials: silver, gold, copper, magnesium, tungsten, and bismuth;

[0037] (4) The particle size Dv50 of the metal nanoparticles is 20nm to 100nm;

[0038] (5) The total mass of the carbon nanomaterial and the metal nanoparticles is 100%, and the mass percentage of the metal nanoparticles is 5% to 50%.

[0039] In some embodiments, the preparation of the interface layer includes the steps of: preparing a mixed slurry of the metal-carbon composite material with a binder and a solvent, forming a wet film layer on the surface of the negative electrode current collector, and drying to obtain the interface layer.

[0040] In some embodiments, in the assembled solid-state battery cell, the positive electrode, the solid electrolyte, the interface layer, and the negative electrode current collector are sequentially stacked.

[0041] 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.

[0042] 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 good cycle life and safety under the premise of high energy density.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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, specific embodiments of this application are given below. Attached Figure Description

[0048] 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:

[0049] Figure 1 This is a schematic diagram of the structure of a solid-state battery cell according to an embodiment of this application;

[0050] Figure 2 for Figure 1 The diagram shows an exploded view of a solid-state battery cell.

[0051] Figure 3 This is a schematic diagram illustrating the synthesis of the Nano-Ag@COOH-SWCNTs metal-carbon composite material according to an embodiment of this application;

[0052] Figure 4 This is a schematic diagram of one embodiment of the battery module of this application;

[0053] Figure 5 This is a schematic diagram of one embodiment of the battery pack of this application;

[0054] Figure 6 for Figure 5 The diagram shows the exploded structure of the battery pack.

[0055] Figure 7 This is a schematic diagram of one embodiment of an electrical device that uses a secondary battery as a power source, as described in the present application.

[0056] Figure 8 The image shows a cross-sectional scanning electron microscope (SEM) image of a solid-state battery cell in Comparative Example 5, in which silver powder and SWCNTs are directly physically mixed and used as the interface layer.

[0057] Figure 9 This is a cross-sectional scanning electron microscope image of a solid-state battery cell with a Nano-Ag@COOH-SWCNTs interface layer in Embodiment 1 of this application;

[0058] The reference numerals in the detailed embodiments are as follows:

[0059] 10-Solid-state battery cell; 11-Housing casing; 12-Top cover assembly; 13-Electrode assembly; 20-Battery module; 30-Battery pack; 31-Upper casing; 32-Lower casing. Detailed Implementation

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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).

[0066] 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.

[0067] 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.

[0068] Currently, from a market perspective, lithium-ion batteries, with their high energy density and good cycle stability, are among the most widely used energy storage systems. Compared to liquid lithium-ion batteries, all-solid-state battery systems using metallic lithium as the negative electrode offer higher energy density and safety. However, unavoidable dendrite growth and interfacial side reactions inhibit the practical application of all-solid-state lithium batteries, and the significant volume expansion during charging and discharging also leads to irreversible capacity degradation.

[0069] To address the problems of all-solid-state battery systems using lithium metal as the anode, some implementations involve first preparing a carbon underlayer on the current collector surface using a dry or wet process, then compositely preparing a lithium replenishment layer, followed by continuous deposition of an alloy layer and a carbon surface layer, and finally obtaining the all-solid-state battery anode through high-temperature treatment and densification. While this method can overcome the technical defects of high-capacity alloy anodes used in all-solid-state batteries, such as low initial efficiency, short cycle life, large volume deformation, and poor interfacial contact, the use of materials such as artificial graphite, natural graphite, soft carbon, and hard carbon in the carbon underlayer and carbon surface layer often inevitably leads to irreversible loss of active lithium on the anode side. Therefore, a lithium replenishment mechanism is needed to improve the battery's initial efficiency. From a process perspective, the lithium replenishment uses pure lithium, which poses difficulties for large-scale processing and production. Furthermore, the introduction of the alloy layer significantly increases the overall cost of the battery.

[0070] Based on the above considerations, in order to solve the technical problems of uneven lithium-ion deposition on the negative electrode side in solid-state batteries, leading to dendrite growth and interfacial side reactions, this application has developed a solid-state battery through in-depth research. An interface layer is formed on the surface of the negative electrode, and this interface layer is in contact with the solid electrolyte. This interface layer, acting as a transition layer for the negative electrode, can effectively induce uniform deposition of lithium metal on the current collector side of the negative electrode, thereby reducing dendrite growth and interfacial side reactions.

[0071] 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 further illustrate the solution of this application and are not intended to limit the scope of this application.

[0072] Solid-state battery cell 10

[0073] Firstly, embodiments of this application provide a solid-state battery cell. In some embodiments, such as... Figure 1 As shown, the solid-state battery cell 10 in this embodiment includes a positive electrode, a solid electrolyte, and a negative electrode current collector stacked sequentially. An interface layer is provided between the solid electrolyte and the negative electrode current collector. The interface layer includes carbon nanomaterials and metal nanoparticles anchored on the surface of the carbon nanomaterials.

[0074] 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., losing electrons) 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., accepting electrons) occurs in the internal electrochemical reaction of the battery. Solid-state electrolyte refers to an electrolyte existing in a solid form, playing the role of transporting ions and blocking electrons. Compared with liquid electrolytes, solid-state electrolytes have the characteristics of being leak-proof, non-deteriorating, and easy to transport. Metal nanoparticles anchored in carbon nanomaterials refer to metal nanoparticles stably loaded in carbon nanomaterials, with strong interaction forces between the two, thus preventing displacement of the metal nanoparticles during battery operation due to repeated lithium ion deposition and stripping, resulting in good material structural stability. This anchoring effect helps maintain the stability and activity of the interface layer.

[0075] The solid-state battery cell 10 provided in this embodiment has an interface layer between the negative electrode current collector and the solid electrolyte layer. This interface layer includes carbon nanomaterials and metal nanoparticles anchored on the surface of the carbon nanomaterials. The carbon nanomaterials possess high electronic / ionic conductivity and exhibit low volume expansion during lithiation. The lithium metal remaining on the surface of the carbon nanomaterials after lithiation can also induce interfacial reactions, forming excellent ion and electron transport channels. Therefore, it can promote efficient lithium-ion transport at the interface between the negative electrode current collector and the solid electrolyte, significantly reducing interfacial resistance. Furthermore, the metal nanoparticles anchored in the carbon nanomaterials do not migrate during charge-discharge cycles due to lithium-ion insertion / extraction, resulting in good material structural stability. The metal nanomaterials can form an alloy with lithium metal. This alloy forms a solid solution in the solid-solid interface gap between the solid electrolyte and the negative electrode current collector. Through the action of pressure and interfacial adhesion, it modifies the interfacial gap, better guiding the uniform transport of lithium ions within the intermediate layer, improving the uniformity of lithium-ion transport and deposition, and inducing uniform deposition of lithium metal on the negative electrode current collector side. Furthermore, the modified metal nanoparticles can largely prevent direct contact between the solid electrolyte material and the carbon nanoparticles, thereby reducing interfacial side reactions and contributing positively to the initial coulombic efficiency of the solid-state battery. In the solid-state battery cell 10 of this application embodiment, the interfacial layer disposed between the solid electrolyte and the negative electrode current collector, through the combined action of the carbon nanoparticles and their anchored metal nanoparticles, can significantly improve the uniformity and efficiency of lithium-ion transport between the solid electrolyte and the negative electrode current collector, induce uniform deposition of lithium metal on the negative electrode current collector side, suppress dendrite formation, reduce interfacial side reactions, and improve the electrochemical performance of the solid-state battery, such as coulombic efficiency, cycle stability, and safety.

[0076] In some embodiments, in the solid-state battery cell 10, the solid electrolyte and the negative electrode current collector form a solid-solid interface. The contact between these interfaces is often point contact or incomplete contact, with cracks and pores present. These defects limit the transport of lithium ions or other ions at the interface, hindering the kinetic process. They can also lead to stress buildup and structural changes at the interface, further affecting kinetic performance. Secondly, due to the poor mobility of atoms or molecules in solid materials, the diffusion rate at the solid-solid interface is typically low, resulting in reduced interface stability and increased interface impedance. In this embodiment, an interface layer is provided between the solid electrolyte and the negative electrode current collector. Metal nanomaterials can form an alloy with metallic lithium. This alloy forms a solid solution in the solid-solid interface gap between the solid electrolyte and the negative electrode current collector, modifying the interface gaps, significantly improving the uniformity and efficiency of lithium ion transport between the solid electrolyte and the negative electrode current collector, inducing uniform deposition of lithium metal on the negative electrode current collector side, suppressing dendrite formation, reducing interface side reactions, and improving the electrochemical performance of the solid-state battery.

[0077] In some embodiments, the solid-state battery cell 10 is a negative electrode-free solid-state battery, that is, the negative electrode of the solid-state battery cell 10 does not contain negative electrode active material. In some embodiments, the negative electrode-free solid-state battery is a lithium-free negative electrode all-solid-state battery. In the first charge of the lithium-free negative electrode all-solid-state battery, lithium ions extracted from the positive electrode are reversibly deposited on the surface of the current collector on the negative electrode side to form a lithium negative electrode. This battery system has the following advantages compared with the current solid-state battery system: ① further improves the volumetric energy density and gravimetric energy density of the battery; ② improves the safety performance of the battery, without the need for excessive metallic lithium; ③ simplifies the manufacturing process, and does not require free metallic lithium during assembly. Compared with lithium-ion all-solid-state batteries containing negative electrode active materials, negative electrode-free solid-state batteries can improve the volumetric energy density of the device to the extreme. However, the lithium source of the negative electrode-free battery comes entirely from the lithium-rich positive electrode side, while the negative electrode is just a current collector. During the charge and discharge process, lithium will be repeatedly deposited and stripped. During the cycle, the uneven deposition of metallic lithium on the current collector forms lithium dendrites, and the volume expansion leads to irreversible lithium capacity loss, resulting in a decrease in the capacity retention rate and a decrease in cycle life of the negative electrode-free battery. The embodiments of this application, through the interface layer set between the negative electrode current collector and the solid electrolyte, can not only reduce the loss of effective contact area caused by volume change through interface engineering, but also enable the uniform distribution of electrons, thereby inducing the uniform deposition of lithium metal on the negative electrode current collector side, regulating the deposition of lithium ions, suppressing the formation of dendrites, reducing interface side reactions, and preventing battery short circuits.

[0078] In some embodiments, the carbon nanomaterials include at least one of single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), graphene, and carbon fibers. On one hand, these carbon nanomaterials all possess high electronic / ionic dual conductivity, and exhibit low volume expansion during lithiation. The lithium metal remaining on the surface of the carbon nanomaterials after lithiation can also induce interfacial reactions, forming excellent ion and electron transport channels, improving the uniformity and efficiency of lithium ion migration and transport at the interface, and promoting uniform lithium ion deposition on the negative electrode side. On the other hand, these carbon nanomaterials are one-dimensional wire or two-dimensional sheet structures, capable of forming a uniform three-dimensional conductive network in the interfacial layer. This not only better guides the uniform and stable migration and transport of ions and electrons, guiding the uniform deposition of lithium metal on the current collector side, but also effectively suppresses the volume expansion caused by volume changes of the deposited lithium metal during charge and discharge, improving the cycle stability of the solid-state battery cell 10. Furthermore, these carbon nanomaterials exhibit better chemical stability and relatively weaker reactivity with lithium metal and solid electrolytes during battery charging and discharging, which helps reduce interfacial side reactions and further improves the cycle stability of the solid-state battery cell 10.

[0079] In some embodiments, the carbon nanomaterials include single-walled carbon nanotubes (SWCNTs). In this case, SWCNTs possess high electronic / ionic dual conductivity, as well as excellent electronic, mechanical, and electrical properties, especially ultra-high mobility for both electrons and holes. They exhibit high structural uniformity and fewer defects, thus demonstrating higher uniformity and stability. Furthermore, due to the confinement effect of SWCNTs, the volume expansion caused by lithiation results in only about 14% tensile strain within the SWCNTs, a lower volume expansion during lithiation. SWCNTs can utilize low volume expansion and induced interfacial reactions to stabilize solid-solid contacts, promoting efficient lithium-ion transport at the interface and significantly reducing interfacial resistance. Additionally, SWCNTs exhibit better additive adhesion, greater compatibility with deposited lithium metal, and superior battery safety. Therefore, after lithiation, the single-walled tubes can form an excellent three-dimensional ion-electron transport network, enabling efficient lithium-ion transport at the interfacial layer.

[0080] In some embodiments, the average diameter of the single-walled carbon nanotubes is 1 nm to 3 nm, and the average length is 1 μm to 5 μm. In this case, the single-walled carbon nanotubes have a high aspect ratio and strong flexibility, and can form a three-dimensional conductive network even with low addition amounts. Their conductivity and ion transport performance are far superior to those of multi-walled carbon nanotubes. For example, the average diameter of the single-walled carbon nanotubes can be any typical but non-limiting point value such as 1 nm, 2 nm, or 3 nm, or a range between any two points. The average length can be any typical but non-limiting point value such as 1 μm, 2 μm, 3 μm, 4 μm, or 5 μm, or a range between any two points.

[0081] In some embodiments, oxygen-containing functional groups are grafted onto the surface of the carbon nanomaterials. In this case, the grafting of oxygen-containing functional groups onto the surface of the carbon nanomaterials not only improves the compatibility of the carbon nanomaterials with solid electrolytes and deposited lithium metal, and reduces interfacial impedance, but also improves the charge distribution on the surface of the carbon nanomaterials, which helps to improve the electrical properties of the carbon nanomaterials, provides better charge transport performance, and is more conducive to uniform lithium ion deposition.

[0082] In some embodiments, the oxygen-containing functional groups include at least one selected from hydroxyl, carboxyl, ether, ester, nitro, and aldehyde groups. These oxygen-containing functional groups are all beneficial for improving the compatibility and electrical properties of carbon nanomaterials.

[0083] In some embodiments, the metallic material in the metal nanoparticles includes at least one of silver, gold, copper, magnesium, tungsten, and bismuth. These metallic materials all possess excellent electron transport properties and can form alloys with metallic lithium. This alloy forms a solid solution in the solid-solid interface gap between the solid electrolyte and the negative electrode current collector. Through the action of pressure and interfacial adhesion, it modifies the interfacial gap, better guides the uniform transport of lithium ions within the intermediate layer, improves the uniformity of lithium ion transport and deposition, and induces uniform deposition of lithium metal on the negative electrode current collector side.

[0084] 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. For example, 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.

[0085] In some embodiments, the connection between the metal nanoparticles and the carbon nanomaterials includes hydrogen bonding. In this case, the metal nanoparticles are stably anchored in the carbon nanomaterials via hydrogen bonds, and the metal nanoparticles do not migrate with the insertion / extraction of lithium ions during charge-discharge cycles, resulting in good material structural stability.

[0086] In some embodiments, the total mass of carbon nanomaterials and metal nanoparticles is 100%, with the metal nanoparticles comprising 5% to 50% of the mass. In this case, the ratio of carbon nanomaterials to metal nanoparticles ensures the bonding stability of the metal-carbon composite material while also guiding the uniform transport of lithium ions within the intermediate layer through the bilayer interaction of the carbon nanomaterials and metal nanoparticles. This improves the uniformity of lithium ion transport and deposition, induces uniform deposition of lithium metal on the negative electrode current collector side, suppresses dendrite formation, reduces interfacial side reactions, and improves the electrochemical performance of solid-state batteries, including coulombic efficiency, cycle stability, and safety. For example, with the total mass of carbon nanomaterials and metal nanoparticles being 100%, the mass percentage of metal nanoparticles can be any typical but non-limiting point value or a range between any two points, such as 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%. In some embodiments, the total mass of carbon nanomaterials and metal nanoparticles is 100%, wherein the mass percentage of metal nanoparticles is 20% to 30%.

[0087] In some embodiments, the interface layer comprises carbon nanomaterials including single-walled carbon nanotubes with carboxyl groups grafted onto their surfaces, and metal nanoparticles anchored to the surface of the carbon nanomaterials including silver nanoparticles. That is, the interface layer includes single-walled carbon nanotubes with carboxyl groups grafted onto their surfaces, and silver nanoparticles are anchored to the surfaces of these single-walled carbon nanotubes. In this case, Li and Ag can form a LiAg alloy, which forms a solid solution in the solid-solid interface gap. Through pressure and interfacial adhesion, lithium ions can be transported and deposited during charging. Furthermore, the Ag nanoparticles are anchored by the carboxyl-grafted single-walled carbon nanotubes and will not shift during the insertion / extraction of lithium ions during charging and discharging, thus maintaining the stability of the material structure. The carboxylated and surface-modified silver nanoparticles of the single-walled carbon nanotubes can, while ensuring electron / ion transport efficiency, largely prevent direct contact between the solid electrolyte material and the conductive single-walled carbon nanotubes, thereby reducing the possibility of side reactions between them and contributing positively to the battery's initial coulombic efficiency.

[0088] In some embodiments, the interface layer also includes a binder; the binder acts to form a stable interface layer comprising carbon nanomaterials and metal nanoparticles anchored therein, thereby improving the stability of the interface layer. In the interface layer of this application embodiment, the binder and the metal-carbon composite material form a homogeneous system. The binder firmly bonds the metal-carbon composite material to the surface of the negative electrode current collector, preventing the interface layer material from detaching and delaminating. This bonding effect ensures the integrity and stability of the interface layer, thereby improving the overall performance of the battery.

[0089] In some embodiments, the binder includes at least one of polyvinylidene fluoride (PVDF), nitrile rubber (NBR), and polytetrafluoroethylene (PTFE). In this case, these binders all possess excellent bonding properties, effectively binding the metal-carbon composite materials and other components in the interface layer tightly together, ensuring the stability and integrity of the battery structure, thereby improving battery efficiency and safety. Furthermore, these binders also exhibit extremely high chemical stability and corrosion resistance, maintaining their performance under various harsh environments, helping to extend battery life and reduce performance degradation caused by material aging or corrosion. They possess good mechanical properties, resisting expansion and contraction during battery cycle charging and discharging, maintaining the stability of the battery structure. When these materials are used as binders in the interface layer, their internal resistance is lower, thereby improving the battery's charge and discharge efficiency.

[0090] In some embodiments, the binder content in the interface layer is 1% to 10% by mass. In this case, the stability and electrochemical performance of the interface layer can be sufficiently ensured. Exemplarily, the binder content can be any typical but non-limiting point value or a range between any two points, such as 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%.

[0091] In some embodiments, the thickness of the interface layer is 10 μm to 15 μm. In this case, the thickness of the interface layer is beneficial for the fabrication process and can better improve the uniformity and efficiency of lithium ion transport between the solid electrolyte and the negative electrode current collector, induce uniform deposition of lithium metal on the negative electrode current collector side, suppress the formation of dendrites, reduce interfacial side reactions, and improve the electrochemical performance of the solid-state battery, such as coulombic efficiency, cycle stability, and safety. Exemplarily, the thickness of the interface layer can be any typical but non-limiting point value or a range between any two points, such as 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, or 15 μm.

[0092] 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.

[0093] 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.

[0094] 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 further, high structural stability and good cycle performance.

[0095] 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 60% to 90%, optionally 70% to 80%. In exemplary examples, it can be a typical but non-limiting content such as 60%, 65%, 70%, 75%, 80%, 85%, 90%, 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.

[0096] 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.

[0097] 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.).

[0098] 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.

[0099] 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.

[0100] In some possible implementations, the solid electrolyte comprises a solid electrolyte and a binder. In some embodiments, the mass ratio of the solid electrolyte to the binder may be 100:(1-5), specifically 100:1, 100:2, 100:3, 100:4, 100:5, etc. 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).

[0101] In some possible implementations, the electrode assembly included in the solid-state battery cell 10 typically includes a positive electrode, a solid electrolyte, an interface layer, and a negative current collector. The solid electrolyte is stacked between the positive and negative current collectors to provide insulation, separating the positive and negative electrodes. The electrode assembly containing the solid electrolyte is placed in an outer package and encapsulated to obtain the solid-state battery cell 10.

[0102] 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.

[0103] In this embodiment, the solid-state battery cell 10 may include a battery casing and electrode assemblies encapsulated within the battery casing. The shape of the solid-state battery cell 10 is not particularly limited; it may be cylindrical, square, or any other arbitrary shape. Figure 1 The solid-state battery cell 10 with a square structure is shown.

[0104] In some possible implementations, such as Figure 2As shown, 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 forming 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 this embodiment, the positive electrode, solid electrolyte 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 within 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.

[0105] Preparation method of solid-state battery cell 10

[0106] Secondly, embodiments of this application provide a method for preparing a solid-state battery cell 10, comprising the following steps:

[0107] S10. Metal nanoparticles are anchored in carbon nanomaterials to obtain metal-carbon composite materials;

[0108] S20. After forming an interface layer on the surface of the negative electrode current collector using a metal-carbon composite material, it is assembled with the positive electrode and a solid electrolyte to obtain a solid-state battery cell 10.

[0109] The method for preparing the solid-state battery cell 10 in this application involves anchoring metal nanoparticles in carbon nanomaterials to obtain a metal-carbon composite material, then using this composite material as an interface layer on the surface of the negative electrode current collector, and finally assembling it with the positive electrode and solid electrolyte to obtain the solid-state battery cell 10. The preparation process is simple and suitable for large-scale industrial production and application. In the interface layer between the negative electrode current collector and the solid electrolyte layer, the carbon nanomaterials exhibit a low volume expansion effect during lithiation. The lithium metal remaining on the surface of the carbon nanomaterials after lithiation can also induce interfacial reactions, promoting efficient lithium ion transport at the interface between the negative electrode current collector and the solid electrolyte, and significantly reducing interfacial resistance. The metal nanoparticles anchored in the carbon nanomaterials have good load stability. The metal nanomaterials can form alloys with lithium metal, modifying the solid-solid interface gap between the solid electrolyte and the negative electrode current collector, better guiding the uniform transport of lithium ions within the intermediate layer, improving the uniformity of lithium ion transport and deposition, and inducing uniform deposition of lithium metal on the negative electrode current collector side. Therefore, through the action of the interface layer, lithium metal is induced to be deposited uniformly on the negative electrode current collector side, suppressing the formation of dendrites, reducing interfacial side reactions, and improving the electrochemical performance of solid-state batteries, such as coulombic efficiency, cycle stability, and safety.

[0110] In step S10 above:

[0111] In some embodiments, the preparation steps of the metal-carbon composite material include:

[0112] S11. Acidification treatment of carbon nanomaterials to obtain acidified carbon materials; by acidification treatment of carbon nanomaterials, oxygen-containing groups such as carboxyl groups and hydroxyl groups are grafted onto the surface of carbon nanomaterials, thereby improving the compatibility and electrochemical performance of carbon nanomaterials.

[0113] In some embodiments, the acidification treatment uses concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 1:(3-5) at a temperature of 60℃ to 80℃; or, the acidification treatment uses concentrated nitric acid at a temperature of 110℃ to 130℃. Concentrated nitric acid refers to a nitric acid solution with a concentration of 8 mol / L or higher. Conventional concentrated nitric acid has a mass fraction of approximately 68%, while nitric acid with a concentration of 98% or higher is called "fuming nitric acid." Concentrated sulfuric acid refers to an aqueous solution of sulfuric acid with a mass fraction greater than or equal to 70%. In this case, hydrogen ions in the strong acid combine with oxides on the surface of the carbon nanomaterial to generate water, removing surface impurities and oxides. Simultaneously, the oxidizing effect of the strong acid causes defects or corrosion fractures on the surface of the carbon nanomaterial, implanting functional groups such as hydroxyl (-OH) and carboxyl (-COOH) groups at these defects or fracture sites. Acidification treatment of carbon nanomaterials with strong acid is an effective surface modification method that can significantly improve the dispersibility, stability, and activity of carbon nanomaterials.

[0114] In some embodiments, concentrated nitric acid and concentrated sulfuric acid are used for acidification treatment of carbon nanomaterials. The temperature conditions can be any typical but non-limiting point value or a range between any two points, such as 60°C, 65°C, 70°C, 75°C, and 80°C. The volume ratio of nitric acid to concentrated sulfuric acid can be any typical but non-limiting point value or a range between any two points, such as 1:3, 1:4, and 1:5.

[0115] In other embodiments, the acidification treatment of carbon nanomaterials is performed using concentrated nitric acid at relatively high temperatures. The temperature conditions can be any typical but non-limiting point value or an interval between any two point values, such as 110°C, 115°C, 120°C, 125°C, or 130°C.

[0116] In some embodiments, the carbon nanomaterials include at least one of single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene, and carbon fibers. These carbon nanomaterials all possess high electronic / ionic dual conductivity, low volume expansion effect, and lithiation-induced interfacial reaction, which can improve the uniformity and efficiency of lithium-ion migration and transport at the interface, promoting uniform lithium-ion deposition on the negative electrode side. Furthermore, they can form a uniform three-dimensional conductive network in the interfacial layer, better guiding the uniform deposition of lithium metal on the current collector side; effectively suppressing volume expansion caused by volume changes of deposited lithium metal during charge and discharge processes, and improving the cycle stability of the solid-state battery cell 10.

[0117] In some embodiments, the carbon nanomaterials include single-walled carbon nanotubes (SWCNTs). After lithiation, the single-walled tubes can form an excellent three-dimensional ion-electron transport network, enabling lithium ions to be transported efficiently at the interface layer.

[0118] In some embodiments, the average diameter of the single-walled carbon nanotubes is 1 nm to 3 nm, and the average length is 1 μm to 5 μm. In this case, the single-walled carbon nanotubes have a high aspect ratio and strong flexibility, and can form a three-dimensional conductive network even with low addition amounts. Their conductivity and ion transport performance are far superior to those of multi-walled carbon nanotubes.

[0119] In some embodiments, a mixed acid of concentrated HNO3 and concentrated H2SO4 in a volume ratio of 1:(3-5) is first prepared. Then, 10 wt% SWCNTs are added to the mixed acid heated at 60-80°C and stirred in a water bath for 1 h. After the acidification reaction is completed, the acidified single-walled carbon nanotubes are separated by centrifugation, washed multiple times with deionized water, and vacuum filtered with a large amount of deionized water until the filtrate is neutral. Finally, the single-walled carbon nanotubes with carboxylic acid grafts on the surface are obtained by freeze-drying and labeled as COOH-SWCNTs.

[0120] S12. Sensitize the acidified carbon material to obtain sensitized carbon material. By sensitizing the acidified carbon material, sensitized metal particles are loaded onto the surface of the acidified carbon material, which facilitates the in-situ generation and anchoring of subsequent target metal nanoparticles.

[0121] In some embodiments, the sensitization treatment is carried out in a solution with a tin salt concentration of 0.02 mol / L to 0.1 mol / L and a hydrochloric acid concentration of 0.5 mol / L to 0.9 mol / L. The hydrochloric acid is used to prevent the hydrolysis of stannous chloride; the amount of hydrochloric acid has little effect on the sensitization effect, and the amount added is limited to prevent the hydrolysis of stannous chloride. In this embodiment, because stannous chloride is readily hydrolyzed in neutral aqueous solution to form basic stannous chloride, the solution becomes milky white, which reduces the sensitization effect and worsens the adhesion between the coating and the substrate. Therefore, when preparing the stannous chloride sensitization solution, it is best to first dissolve the stannous chloride in hydrochloric acid, and then dilute it with water after complete dissolution. Furthermore, to prevent the sensitization solution from easily reacting with oxygen in the air and losing its reducing ability, and to prevent Sn... 2+ Oxidized to Sn 4+ Metal tin bars or tin granules can be added to the sensitizing solution to make Sn 4+ Reduced to Sn 2+ In this case, Sn in the solution 2+ Tin ions can be uniformly loaded into carbon nanomaterials, and their concentration ensures the sensitization effect on carbon nanomaterials. Hydrochloric acid solution improves the dispersion performance of carbon nanomaterials.

[0122] For example, in the solution used for sensitization treatment, the concentration of tin salt can be any typical but non-limiting point value or an interval between any two points, such as 0.02 mol / L, 0.03 mol / L, 0.04 mol / L, 0.05 mol / L, 0.06 mol / L, 0.07 mol / L, 0.08 mol / L, 0.09 mol / L, 0.1 mol / L, and the concentration of hydrochloric acid can be any typical but non-limiting point value or an interval between any two points, such as 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L.

[0123] In some embodiments, the tin salt can be SnCl2·2H2O. In this case, the sensitization treatment step includes: dissolving SnCl2·2H2O in a 0.5 mol / L to 0.9 mol / L HCl aqueous solution to make the SnCl2 concentration 0.02 mol / L to 0.1 mol / L; adding COOH-SWCNTs to make the concentration 0.1 g / L to 20 g / L; sonicating for 30 min to 60 min; centrifuging to separate the sensitization product; washing several times with deionized water to obtain Sn. 2+ Sensitized SWCNTs. Finally, Sn 2+ The sensitized SWCNTs were dispersed in 10 ml of deionized water for later use. The treatment temperature and time should be appropriately adjusted. When the concentration of the sensitizing solution is low, the sensitization time can be appropriately extended.

[0124] In other embodiments, the sensitization treatment may also employ trivalent titanium salts.

[0125] S13. A mixed reduction reaction is carried out between sensitized carbon material and metal salt solution to generate metal nanoparticles in situ on the surface of carbon nanomaterial, resulting in a metal-carbon composite material. Through the mixed reduction reaction, the sensitizing ions such as tin loaded in the carbon nanomaterial reduce the metal ions in the metal salt solution into metal nanoparticles, thereby anchoring the metal nanoparticles in situ within the carbon nanomaterial.

[0126] In some embodiments, the metal salt solution is an ammoniacal metal nitrate solution. In this case, the metal salt solution is prepared as an ammoniacal metal nitrate solution, which makes the metal solution have strong reducing properties, making it more conducive for sensitizing ions such as tin to reduce metal ions into metal nanoparticles, thereby anchoring the metal nanoparticles in situ within the carbon nanomaterial.

[0127] In some embodiments, the temperature conditions for the mixed reduction reaction are 20°C to 40°C; under these temperature conditions, sensitized ions such as tin loaded on the surface of the carbon nanomaterial can efficiently reduce metal ions into metal nanoparticles that are anchored in situ to the surface of the carbon nanomaterial. Exemplarily, the temperature conditions for the mixed reduction reaction can be any typical but non-limiting point value or a range between any two points, such as 20°C, 25°C, 30°C, 35°C, or 40°C.

[0128] In some embodiments, the metal nanoparticles contain at least one of silver, gold, copper, magnesium, tungsten, and bismuth. These metal materials all possess excellent electron transport properties and can form alloys with metallic lithium, modifying interfacial gaps, better guiding the uniform transport of lithium ions within the intermediate layer, improving the uniformity of lithium ion transport and deposition, and inducing uniform deposition of lithium metal on the negative electrode current collector side.

[0129] 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 induction 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.

[0130] In some embodiments, silver salts such as AgNO3 are dissolved in deionized water, and an aqueous solution of approximately 0.1M NaOH is added while stirring. Ammonia (approximately 6.6 wt.%) is added dropwise while stirring until the solution color changes from brown to clear. The addition of ammonia is then immediately stopped, thus preparing a silver ammonia solution, i.e., an ammoniacal silver nitrate solution. Then, sensitized single-arm carbon nanotubes are dispersed in the ammoniacal silver nitrate solution. After stirring at 20℃–40℃ for 30 min–2 h, the reaction product is separated by centrifugation, washed multiple times with deionized water, and freeze-dried to obtain a metal-carbon composite material.

[0131] In some embodiments, in the metal-carbon composite material, the total mass of carbon nanomaterials and metal nanoparticles is 100%, and the mass percentage of metal nanoparticles is 5% to 50%. In this case, the bonding stability of the metal-carbon composite material is fully ensured, and the bilayer effect of carbon nanomaterials and metal nanoparticles can guide the uniform transport of lithium ions in the intermediate layer, improve the uniformity of lithium ion transport and deposition, induce uniform deposition of lithium metal on the negative electrode current collector side, suppress the formation of dendrites, reduce interfacial side reactions, and improve the electrochemical performance of solid-state batteries, such as coulombic efficiency, cycle stability, and safety.

[0132] In some embodiments, the metal-carbon composite material includes single-walled carbon nanotubes with carboxyl groups grafted onto their surfaces, and silver nanoparticles are anchored to the surface of the single-walled carbon nanotubes. This metal-carbon composite material is labeled Nano-Ag@COOH-SWCNTs, and its synthesis steps are as follows. Figure 3 And the following steps are shown:

[0133] S111. First, a mixed acid of concentrated HNO3 and concentrated H2SO4 with a volume ratio of 1:(3-5) was prepared. Then, 10 wt% SWCNTs were added to the mixed acid and stirred in a water bath at 60℃-80℃ for 1 h. After the acidification reaction was completed, the acidified single-walled carbon nanotubes were separated by centrifugation, washed several times with deionized water, and vacuum filtered with a large amount of deionized water until the filtrate was neutral. Finally, the single-walled carbon nanotubes with carboxylic acid grafts on the surface were obtained by freeze-drying and labeled as COOH-SWCNTs.

[0134] S121. Dissolve SnCl2·2H2O in a 0.5 mol / L to 0.9 mol / L HCl aqueous solution to make the SnCl2 concentration 0.02 mol / L to 0.1 mol / L. Add COOH-SWCNTs to make the concentration 0.1 g / L to 20 g / L, sonicate for 30 min to 60 min, centrifuge to separate the sensitized product, wash several times with deionized water to obtain Sn. 2+ Sensitized SWCNTs. Finally, Sn 2+ The sensitized SWCNTs were dispersed in 10 ml of deionized water for later use.

[0135] S131. Dissolve silver salts such as AgNO3 in deionized water. While stirring, add an approximately 0.1M NaOH aqueous solution. Simultaneously, add ammonia water (approximately 6.6 wt.%) dropwise while stirring until the solution color changes from brown to clear. Immediately stop adding ammonia water to prepare a silver ammonia solution, i.e., ammoniacal silver nitrate solution. Then, add Sn... 2+ Sensitized SWCNTs were dispersed in an ammoniacal silver nitrate solution and stirred at 20℃~40℃ for 30min~2h. The reaction product was then separated by centrifugation, washed multiple times with deionized water, and freeze-dried to obtain the metal-carbon composite material, namely Nano-Ag@COOH-SWCNTs.

[0136] In some embodiments, the preparation of the interface layer includes the steps of: preparing a mixed slurry of metal-carbon composite material with binder and solvent, forming a wet film layer on the surface of the negative electrode current collector, and drying to obtain the interface layer.

[0137] In some embodiments, the binder includes at least one of polyvinylidene fluoride (PVDF), nitrile rubber (NBR), and polytetrafluoroethylene (PTFE). These binders all have excellent bonding properties, extremely high chemical stability and corrosion resistance, and good mechanical properties. They can effectively bind the metal-carbon composite materials and other components in the interface layer tightly together, resist the expansion and contraction during battery cycle charging and discharging, ensure the stability and integrity of the battery structure, thereby improving the battery's working efficiency and safety, and helping to extend the battery's service life.

[0138] In some embodiments, the mass ratio of the metal-carbon composite material to the binder is 100 (2 to 10). Exemplarily, the mass ratio can be any typical but non-limiting point value or a range between any two points, such as 100:2, 100:3, 100:4, 100:5, 100:6, 100:7, 100:8, 100:9, or 100:10. In this case, the stability of the interface layer and its electrochemical performance can be sufficiently ensured.

[0139] In some embodiments, the solvent includes N-methylpyridinone (NMP), acetone, ethanol, butanedione, etc.

[0140] In some embodiments, the Nano-Ag@COOH-SWCNTs interface layer is prepared by wet coating, including the following steps: First, the metal-carbon composite material Nano-Ag@COOH-SWCNTs and a binder such as polyvinylidene fluoride (PVDF) are ground in a solvent such as N-methylpyridinone (NMP) at a mass ratio of 100:(2-10) until the slurry is uniform and smooth. The slurry is then coated onto a rough surface of a copper foil / stainless steel current collector with a thickness of 9μm to 12μm using a coating machine. The surface is then dried under vacuum and cut and weighed to obtain the interface layer.

[0141] In some embodiments, in the assembled solid-state battery cell 10, the positive electrode, solid electrolyte, interface layer and negative electrode current collector are stacked in sequence.

[0142] In step S20 above, a positive electrode and a solid electrolyte are provided, and the positive electrode, solid electrolyte, interface layer and negative electrode current collector are assembled to obtain a solid battery cell 10.

[0143] 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.

[0144] 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 package and subjected to processes such as vacuum sealing, settling, formation, and shaping to obtain the solid-state battery cell 10.

[0145] 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 as follows: Figure 1 The solid-state battery cell 10 with a square structure is shown.

[0146] Battery device

[0147] 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.

[0148] 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 good safety and cycle life under the premise of high energy density.

[0149] 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.

[0150] 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.

[0151] 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.

[0152] In some implementations, as shown in the appendix Figure 4This is a schematic diagram of a battery module 20 as an example. In the battery module 20, multiple solid-state battery cells 10 can be arranged sequentially along the length of the battery module 20. Of course, they can also be arranged in any other manner. Furthermore, the multiple 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 multiple solid-state battery cells 10 are received.

[0153] 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.

[0154] As in the embodiments, as shown in the appendix Figure 5 and attached Figure 6 This is a schematic diagram of a battery pack 30 as an example. The battery pack 30 may include a battery compartment and multiple battery modules 20 disposed within the battery compartment. The battery compartment includes an upper compartment 31 and a lower compartment 32. The upper compartment 31 covers the lower compartment 32, forming a closed space for accommodating the battery modules 20. The multiple battery modules 20 can be arranged in any manner within the battery compartment.

[0155] Electrical appliances

[0156] 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.

[0157] 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.

[0158] 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.

[0159] As attached Figure 7This is a schematic diagram of an example electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the device's requirements for high power and high energy density, a battery pack or battery module can be used.

[0160] 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.

[0161] Energy storage devices

[0162] 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.

[0163] 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.

[0164] 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.

[0165] 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.

[0166] In some implementations, the energy storage device is an energy storage container or an energy storage cabinet.

[0167] In some implementations, the energy storage device may include a cabinet and one or more battery clusters housed within the cabinet.

[0168] 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.

[0169] Example

[0170] 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.

[0171] Example 1

[0172] A solid-state battery cell 10 is prepared by the following steps:

[0173] 1. Synthesis of Nano-Ag@COOH-SWCNTs:

[0174] ① Preparation of COOH-SWCNTs: First, prepare a mixed acid solution of 25 ml concentrated HNO3 and 75 ml concentrated H2SO4. Then, add 20 ml of 10 wt% SWCNTs to a 70°C heated acid water bath and stir for 1 h. Centrifuge at 5000 rpm for 3 min to obtain COOH-SWCNTs, wash four times with deionized water, and vacuum filter with a large amount of deionized water until the filtrate is neutral. Finally, freeze-dry for 24 h to obtain COOH-SWCNTs.

[0175] ②Preparation of Sn 2+ Sensitized SWCNTs: Dissolve 0.6 g SnCl2·2H2O in 50 ml of 0.1 M HCl aqueous solution, add 0.25 g COOH-SWCNTs, and sonicate for 45 min. Centrifuge at 5000 rpm for 3 min, and wash three times with deionized water to obtain Sn. 2+ Sensitized SWCNTs. Finally, Sn 2+ The sensitized SWCNTs were dispersed in 10 ml of deionized water for later use.

[0176] ③ Preparation of Nano-Ag@COOH-SWCNTs (NACS): Dissolve 0.5g AgNO3 in 40ml deionized water, and add 0.2ml of 0.1M NaOH aqueous solution while stirring. Add 2.5ml of ammonia water (6.6wt.%) to form an ammoniacal silver nitrate solution. Add Sn... 2+ Sensitized SWCNTs dispersions were added to ammoniacal silver nitrate solution, stirred at 25°C for 1 h, centrifuged at 5000 rpm for 3 min, washed three times with deionized water, and freeze-dried for 24 h to obtain Nano-Ag@COOH-SWCNTs, wherein the particle size Dv50 of silver nanoparticles was 100 nm, and the mass ratio of silver nanoparticles to SWCNTs was 4:6.

[0177] 2. Preparation of the interface layer on the surface of the negative electrode current collector: The Nano-Ag@COOH-SWCNTs interface layer was prepared by wet coating: First, Nano-Ag@COOH-SWCNTs and polyvinylidene fluoride (PVDF) binder were ground in N-methylpyridinone (NMP) at a mass ratio of 100:10 until the slurry was uniform and smooth. The slurry was then coated onto a rough surface of 10μm thick copper foil / stainless steel using a coating machine. The surface was dried at 120℃ for 12h under vacuum. The interface layer was obtained by cutting and weighing.

[0178] 3. Dry preparation of positive electrode sheet: The positive electrode is prepared by mixing lithium nickel cobalt manganese oxide, conductive carbon black and solid electrolyte sulfide in a mass ratio of 70:5:30.

[0179] 4. Preparation of solid electrolyte layer: The electrolyte layer is prepared by mixing sulfide electrolyte LPSCl and binder PTFE (polytetrafluoroethylene) at a ratio of 100:3.

[0180] 5. Battery assembly: The cells are assembled in the order of positive electrode - solid electrolyte - interface layer - negative electrode current collector stacking. After high-temperature densification treatment, a soft-pack battery is obtained.

[0181] Examples 2-4

[0182] Examples 2-4 each provide a solid-state battery cell 10, the main difference from Example 1 being the type of carbon material, as shown in Table 1 below.

[0183] Examples 5-9

[0184] Examples 5-9 each provide a solid-state battery cell 10, the main difference from Example 1 is that the ratio of carbon nanomaterials to metal nanoparticles in the metal-carbon composite material is different, as shown in Table 1 below.

[0185] Examples 10-14

[0186] Examples 10-14 each provide a solid-state battery cell 10, the main difference from Example 1 being that the metal-carbon composite material has a different type of metal material, as shown in Table 1 below.

[0187] Examples 15-19

[0188] Examples 15-19 each provide a solid-state battery cell 10, the main difference from Example 1 being the thickness of the interface layer on the surface of the negative electrode current collector, as shown in Table 1 below.

[0189] Examples 20-23

[0190] Examples 20-23 each provide a solid-state battery cell 10, the main difference from Example 1 is that the ratio of metal-carbon composite material to binder in the interface layer is different, as shown in Table 1 below.

[0191] Comparative Example 1

[0192] A solid-state battery cell 10 differs from Example 1 in that it uses COOH-SWCNTs prepared in step 1-① of Example 1 instead of the metal-carbon composite material of the present application.

[0193] Comparative Example 2

[0194] A solid-state battery cell 10 differs from Example 1 in that it uses untreated and unmodified SWCNTs instead of the metal-carbon composite material of the present application.

[0195] Comparative Example 3

[0196] A solid-state battery cell 10 differs from Example 1 in that it uses MWCNTs instead of the metal-carbon composite material of the present application.

[0197] Comparative Example 4

[0198] A solid-state battery cell 10 differs from Example 1 in that carbon black is used instead of the metal-carbon composite material of the present application.

[0199] Comparative Example 5

[0200] A solid-state battery cell 10 differs from Example 1 in that it uses a direct mixture of silver powder and SWCNTs instead of the metal-carbon composite material of the present application. Specifically, the silver powder used has a particle size Dv50 of 50 nm, and the physical mixing method of the silver powder and SWCNTs is dry mixing using a vortex mixer.

[0201] The substances used in the above embodiments and comparative examples are shown in Table 1 below:

[0202] Table 1

[0203]

[0204]

[0205] Performance testing:

[0206] The following performance tests were performed on the above embodiments and comparative examples:

[0207] 1. First-cycle discharge capacity (mAh / g) test conditions: 60℃, loading pressure 50MPa, 0.1C charging, 0.1C discharging;

[0208] 2. First-cycle coulombic efficiency (%) test conditions: 60℃, loading pressure 50MPa, 0.1C charging, 0.1C discharging;

[0209] 3. 2C discharge capacity (mAh / g) test conditions: 60℃, loading pressure 50MPa, 0.1C charging, 0.2C discharging;

[0210] 4. Capacity retention rate (%) after 100 cycles: 60℃, loading pressure 50MPa, 0.33C charging, 0.33C discharging, 100 cycles;

[0211] 5. The deposition of lithium metal in the solid-state battery cells 10 prepared in Example 1 and Comparative Example 5 was observed using scanning electron microscopy. The test results are attached. Figure 8 and 9 As shown. Among them, Figure 8 The image shown is a cross-sectional scanning electron microscope (SEM) image of a solid-state battery cell 10, which uses a direct physical mixture of silver powder and SWCNTs as the interface layer, as shown in Comparative Example 5. It is evident that the lithium metal deposition on the surface of the negative electrode current collector is uneven, and the interface gap between the lithium metal deposition layer and the silver-carbon interface layer is large, resulting in high resistance, which is detrimental to the uniform and stable migration and transport of ions and electrons. Figure 9 This is a cross-sectional scanning electron microscope (SEM) image of the solid-state battery cell 10 using the Nano-Ag@COOH-SWCNTs interface layer in Embodiment 1 of this application. It can be seen that the lithium metal deposition on the surface of the negative electrode current collector is uniform, and the interface compatibility between the lithium metal layer and the Nano-Ag@COOH-SWCNTs interface layer is good, with small gaps and low resistance, which is conducive to the uniform and stable migration and transport of ions and electrons. It should be noted that the gaps in the SEM image are due to stress release during battery disassembly, which causes gaps between the interface layer and the lithium, and is a normal phenomenon.

[0212] The test results are shown in Table 2 below:

[0213] Table 2

[0214]

[0215]

[0216] The test results above show that, compared to the comparative example, the solid-state battery cells in this application exhibit better coulombic efficiency and cycle stability. This demonstrates that by setting an interface layer comprising carbon nanomaterials and anchored metal nanoparticles between the solid electrolyte and the negative electrode current collector, this application significantly improves the uniformity and efficiency of lithium-ion transport between the solid electrolyte and the negative electrode current collector, induces uniform deposition of lithium metal on the negative electrode current collector side, suppresses dendrite formation, reduces interfacial side reactions, and improves the electrochemical performance of the solid-state battery, including coulombic efficiency, cycle stability, and safety. It should be noted that in Examples 5-9, since metal nanoparticles are the dominant material (high proportion of metal nanoparticles), the metal nanoparticles will form a large amount of Li alloy, which will consume lithium ions to some extent, resulting in insufficient capacity release. In Examples 17 and 19, the significantly increased interface layer thickness will lead to a certain increase in lithium absorption, causing the capacity to be mainly consumed by dead lithium in the carbon layer. In Examples 22-23, the high binder content in the interface layer, coupled with the non-conductive nature of the binder, will reduce the overall electronic and ionic conductivity to some extent.

[0217] 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, characterized in that, It includes a positive electrode, a solid electrolyte, and a negative electrode current collector stacked in sequence. An interface layer is provided between the solid electrolyte and the negative electrode current collector. The interface layer includes carbon nanomaterials and metal nanoparticles anchored on the surface of the carbon nanomaterials.

2. The solid-state battery cell as described in claim 1, characterized in that, The solid-state battery cell is a negative electrode-free solid-state battery.

3. The solid-state battery cell according to any one of claims 1 to 2, characterized in that, The carbon nanomaterials include at least one of single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene, and carbon fibers. And / or, the surface of the carbon nanomaterial is grafted with oxygen-containing functional groups.

4. The solid-state battery cell as described in claim 3, characterized in that, The carbon nanomaterials include single-walled carbon nanotubes; And / or, the average diameter of the single-walled carbon nanotubes is 1 nm to 3 nm, and the average length is 1 μm to 5 μm; And / or, the oxygen-containing functional group includes at least one of hydroxyl, carboxyl, ether, ester, nitro, and aldehyde groups.

5. The solid-state battery cell according to any one of claims 1 to 4, characterized in that, The metallic nanoparticles contain at least one of the following metallic materials: silver, gold, copper, magnesium, tungsten, and bismuth. And / or, the particle size Dv50 of the metal nanoparticles is 20nm to 100nm; And / or, the connection between the metal nanoparticles and the carbon nanomaterial includes hydrogen bonding.

6. The solid-state battery cell according to any one of claims 1 to 5, characterized in that, With the total mass of the carbon nanomaterial and the metal nanoparticles being 100%, the mass percentage of the metal nanoparticles is 5% to 50%. And / or, in the interface layer, the carbon nanomaterial includes single-walled carbon nanotubes with carboxyl groups grafted onto their surface, and the metal nanoparticles anchored to the surface of the carbon nanomaterial include silver nanoparticles.

7. The solid-state battery cell according to any one of claims 1 to 6, characterized in that, The interface layer also contains an adhesive; And / or, the thickness of the interface layer is 10μm to 15μm.

8. The solid-state battery cell as described in claim 7, characterized in that, The adhesive includes at least one of polyvinylidene fluoride, nitrile rubber, and polytetrafluoroethylene; And / or, in the interface layer, the mass percentage of the adhesive is 1% to 10%.

9. A method for preparing a solid-state battery cell, characterized in that, Includes the following steps: Metal nanoparticles are anchored in carbon nanomaterials to prepare metal-carbon composite materials; After the metal-carbon composite material is formed into an interface layer on the surface of the negative electrode current collector, it is assembled with the positive electrode and solid electrolyte to obtain a solid-state battery cell.

10. The method for preparing a solid-state battery cell as described in claim 9, characterized in that, The preparation steps of the metal-carbon composite material include: The carbon nanomaterials are subjected to acidification treatment to obtain acidified carbon materials; The acidified carbon material is sensitized to obtain a sensitized carbon material; The sensitized carbon material is mixed with a metal salt solution for a reduction reaction, and the metal nanoparticles are generated in situ on the surface of the carbon nanomaterial to obtain the metal-carbon composite material.

11. The method for preparing a solid-state battery cell as described in claim 10, characterized in that, The acidification treatment uses concentrated nitric acid and concentrated sulfuric acid at a volume ratio of 1:(3-5) at a temperature of 60℃ to 80℃; or, the acidification treatment uses concentrated nitric acid at a temperature of 110℃ to 130℃. And / or, the sensitization treatment is carried out in a solution with a tin salt concentration of 0.02 mol / L to 0.1 mol / L and a hydrochloric acid concentration of 0.5 mol / L to 0.9 mol / L; And / or, the temperature conditions for the mixed reduction reaction are 20℃~40℃; And / or, the metal salt solution is an ammoniacal metal nitrate solution.

12. The method for preparing a solid-state battery cell according to any one of claims 9 to 11, characterized in that, The metal-carbon composite material has at least one of the following characteristics (1) to (5): (1) The carbon nanomaterials include at least one of single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene, and carbon fibers; (2) The surface of the carbon nanomaterial is grafted with carboxyl groups; (3) The metal nanoparticles contain at least one of the following metal materials: silver, gold, copper, magnesium, tungsten, and bismuth; (4) The particle size Dv50 of the metal nanoparticles is 20nm to 100nm; (5) The total mass of the carbon nanomaterial and the metal nanoparticles is 100%, and the mass percentage of the metal nanoparticles is 5% to 50%.

13. The method for preparing a solid-state battery cell according to any one of claims 9 to 12, characterized in that, The preparation of the interface layer includes the following steps: after preparing the metal-carbon composite material with a binder and a solvent into a mixed slurry, a wet film layer is formed on the surface of the negative electrode current collector, and the interface layer is obtained by drying. And / or, in the assembled solid-state battery cell, the positive electrode, the solid electrolyte, the interface layer and the negative electrode current collector are sequentially stacked.

14. A battery device, characterized in that, 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 13.

15. An electrical appliance, characterized in that, 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 13, or battery devices as described in claim 14.

16. An energy storage device, characterized in that, 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 13, or battery devices as described in claim 14.

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