A silicon-based lithium-ion battery with a confinement component, its fabrication method and application

Abstract

This invention relates to a silicon-based lithium-ion battery with a constraint component, its fabrication method, and its applications. The silicon-based lithium-ion battery includes a core, a shell, and a constraint component. The constraint component includes a constraint frame and an elastic buffer layer. The constraint frame includes at least one set of relatively parallel planar bodies. The constraint frame is disposed on the outside of the core, and the elastic buffer layer is located between the core and the constraint frame, covering the core. The shell is disposed on the outside of the constraint component. The constraint frame is connected to the core, and the shell is connected to the constraint frame. The elastic buffer layer of this invention allows the concentrated force of the rigid frame to be converted into uniform surface pressure acting on the surface of the core. The rigid frame simultaneously acts as a current collector and is directly connected to the core, achieving integration of mechanical constraint and current collection. The shell is connected to the rigid frame as an integrated structure, enhancing overall integrity and reducing weight. The battery exhibits longer cycle life, higher energy density, higher pressure distribution uniformity, stronger packaging compatibility, and better interface stability.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, and in particular to a silicon-based lithium-ion battery with a confinement component, its preparation method, and its application. Background Technology

[0002] High-energy-density lithium-ion batteries are key to the development of portable electronic devices, electric vehicles, and more. Silicon-based anode materials have become an ideal alternative to traditional graphite anodes due to their extremely high theoretical specific capacity (~4200 mAh / g). However, silicon materials undergo significant volume expansion (>300%) during lithium intercalation, leading to electrode particle pulverization, separation of active material from current collector, and repeated rupture and regeneration of the solid electrolyte interphase (SEI) film. Ultimately, this results in rapid capacity decay and shortened cycle life.

[0003] To address this issue, one effective method in existing technologies is to apply mechanical constraints to the outside of the battery to suppress electrode expansion. For example, existing technologies have achieved significant results by introducing a rigid constraint system into the three-dimensional battery structure to apply constant pressure to the cell. Silyte has also been introduced in existing technologies. TM The pure silicon anode, through its porous flexible structure design, can maintain 80% of its capacity after 500 cycles without external pressure. SCC55 has also been launched. TM Silicon-carbon composite materials are designed to completely replace graphite. Existing technologies also optimize packaging methods to accommodate silicon expansion: battery packaging is mainly divided into three types: square (steel / aluminum shell), cylindrical (steel / aluminum shell), and pouch (aluminum-plastic film). Among them, aluminum-plastic film is considered one of the ideal choices for adapting to silicon anodes and future solid-state batteries due to its lightweight, good flexibility, and ability to buffer volume expansion.

[0004] Furthermore, there have been commercial explorations in the industry to achieve 100% all-silicon anodes, such as the 15000mAh concept battery jointly released by realme and Guanyu, and the aforementioned Silyte. TM All of these studies demonstrate the technical feasibility of all-silicon anodes.

[0005] However, the above-mentioned technical solutions still have the following inherent defects: Uneven pressure distribution: A single rigid constraint system is difficult to apply uniform pressure across the entire plane of the cell, usually exhibiting high pressure at the edges and low pressure at the center, resulting in inconsistent constraint effects and the possibility of failure in local areas; Battery energy density loss: To achieve effective constraint, heavy metal constraint components and casings are usually required, which reduces the weight energy density and volumetric energy density of the battery system; Interface reliability challenges: The connection points between the constraint components and the electrodes and casing are prone to fatigue failure under long-term cyclic stress, leading to relaxation of constraint pressure or disconnection; Challenges of all-silicon anodes: Although there have been breakthroughs in the materials themselves, how to suppress the huge volume expansion of large-size power batteries in more demanding application environments remains a key challenge to ensure the overall lifespan and safety of the battery.

[0006] Therefore, how to provide a new type of battery constraint component that can provide uniform, efficient, and lightweight constraint, adapt to different shell materials, cope with high proportions or even full silicon anode expansion, and be used in silicon-based lithium-ion batteries is a technical problem that urgently needs to be solved. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a silicon-based lithium-ion battery with a constraint component, its fabrication method, and its applications. The constraint component provided by this invention includes a rigid frame and an elastic buffer layer. The elastic buffer layer converts the concentrated force of the rigid frame into uniform surface pressure acting on the core surface. The rigid frame simultaneously functions as a current collector, and its connection to the core integrates mechanical constraint and current collection, simplifying the structure and optimizing the force / electricity / heat transfer path. Connecting the outer shell and the rigid frame into an integrated structure enhances overall integrity and reduces weight. The silicon-based lithium-ion battery with a constraint component provided by this invention exhibits longer cycle life, higher energy density, higher pressure distribution uniformity, stronger packaging compatibility, and superior interface stability.

[0008] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a silicon-based lithium-ion battery with a constraint component, the silicon-based lithium-ion battery comprising a core, a shell, and a constraint component, the constraint component comprising a constraint frame and an elastic buffer layer, the constraint frame comprising at least a set of relatively parallel planar bodies; The constraint frame is disposed on the outside of the core, the elastic buffer layer is located between the core and the constraint frame and covers the core, and the outer shell is disposed on the outside of the constraint component; The constraint frame is connected to the core, and the outer shell is connected to the constraint frame.

[0009] The constraint component provided by this invention includes a rigid frame and an elastic buffer layer. The elastic buffer layer converts the concentrated force of the rigid frame into uniform surface pressure acting on the core surface, which can more effectively suppress the expansion of high-proportion silicon anodes (including up to 100% silicon anodes). The rigid frame also acts as a current collector, and its connection with the core integrates mechanical constraint and current collection, simplifying the structure and optimizing the force / electricity / heat transfer path. Connecting the shell and the rigid frame into an integrated structure, the shell-constraint frame co-encapsulation enhances overall integrity, reduces weight, and is compatible with various shell encapsulation forms. The silicon-based lithium-ion battery with constraint component provided by this invention has a longer cycle life, higher energy density, higher pressure distribution uniformity, stronger packaging compatibility, and better interface stability.

[0010] It should be noted that in this invention, the elastic buffer layer can completely cover the surface of the core, or it can partially cover the surface of the core.

[0011] As a preferred embodiment of the present invention, the first region of the constraint frame includes a plurality of conductive connection portions, and the constraint frame is connected to the core through the conductive connection portions.

[0012] And / or, the constraint frame further includes a connecting portion between the relatively parallel planar bodies for fixing the relatively parallel planar bodies.

[0013] And / or, the edge of the constraint frame includes a connection area, through which the housing is connected to the constraint frame.

[0014] And / or, the elastic buffer layer is located between the core and the planar body in the constraint frame.

[0015] In this invention, an elastic buffer layer is placed between the core and the planar body in the constraint frame, which can better buffer volume expansion.

[0016] As a preferred embodiment of the present invention, the core includes at least one single electrode group, the single electrode group including a positive electrode sheet, a separator and a negative electrode sheet stacked together, the positive electrode sheet including a positive current collector and a positive active material layer located on at least one side surface of the positive current collector, the negative electrode sheet including a negative current collector and a negative active material layer located on at least one side surface of the negative current collector, and the constraint frame is connected to the positive current collector and / or the negative current collector through the conductive connection portion.

[0017] And / or, the connection area includes any one of an interlocking structure, a welded joint, or a flange, wherein the interlocking structure includes at least one of a groove, a rib, or a through hole.

[0018] And / or, the elastic buffer layer includes a first elastic material layer and a second elastic material layer stacked together, the first elastic material layer being close to the core and the second elastic material layer being away from the core, the elastic modulus E1 of the first elastic material layer and the elastic modulus E2 of the second elastic material layer satisfying E2≥10×E1, for example 10×E1, 20×E1, 100×E1, 200×E1, 500×E1, 800×E1, 1000×E1, 1200×E1, 1500×E1, 1800×E1, 2000×E1, 2200×E1, 2500×E1, 2800×E1, 3000×E1, 3500×E1 or 4000×E1, etc., preferably E2≥20×E1.

[0019] This invention features a gradient elastic layer with E2 ≥ 10 × E1 adjusted along the thickness direction (from the side near the core to the side near the constraint frame). This gradient design ensures a smooth transition of mechanical pressure from the rigid frame to the core, thereby converting the concentrated force of the frame into uniform surface pressure acting on the core surface and effectively avoiding stress concentration. If E2 < 10 × E1, the modulus change of the gradient buffer layer is too small, making it difficult to effectively convert the concentrated force of the rigid frame into uniform surface pressure acting on the core surface, resulting in poor pressure dispersion and the possibility of stress concentration. This fails to fully leverage the advantages of this invention in improving pressure distribution uniformity and cycle life.

[0020] As a preferred embodiment of the present invention, the total area of ​​the conductive connection portion accounts for 0.1%-30% of the area of ​​the first region, for example 0.1%, 1%, 3%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28% or 30%, preferably 5%-10%.

[0021] And / or, the area of ​​the first region accounts for 0%-100% of the total area of ​​the constraint frame, excluding 0, for example, 1%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or 100%, etc., preferably 10%-90%.

[0022] It should be noted that the location of the first region is not specifically required or limited in this invention, and it can be located anywhere in the constraint frame. Those skilled in the art can make adaptive selections and adjustments according to actual conditions.

[0023] And / or, the planar body includes at least one of a solid plate, a frame, or a truss structure.

[0024] It should be noted that this invention does not impose specific requirements or limitations on the shape of the frame. Common frame shapes in the art are applicable to this invention, such as triangular frames, circular frames, or polygonal frames (with ≥4 sides). In this invention, the truss structure refers to a spatial support skeleton structure formed by multiple members connected at their ends, using triangles or polygons as basic units.

[0025] And / or, the thickness of the planar body is 0.5mm-3.0mm, for example 0.5mm, 0.8mm, 1mm, 1.2mm, 1.5mm, 1.8mm, 2mm, 2.2mm, 2.5mm, 2.8mm or 3.0mm, preferably 0.8mm-2.0mm.

[0026] In this invention, the thickness of the planar body is adjusted to 0.5mm-3.0mm, which can provide sufficient rigidity while also meeting the lightweight requirements of the battery system. If the thickness of the planar body is too thin, the rigidity of the constraint frame will be insufficient, making it difficult to effectively suppress the expansion of the silicon anode; if the thickness of the planar body is too thick, although it can provide stronger constraint, it will unnecessarily increase the weight and volume of the battery, resulting in a decrease in battery energy density.

[0027] And / or, the material of the constraint frame includes at least one of aluminum alloy, titanium alloy, magnesium alloy or carbon fiber reinforced composite material.

[0028] And / or, the Young's modulus of the constraint frame is ≥70 GPa, such as 70 GPa, 80 GPa, 90 GPa, 100 GPa, 110 GPa, 120 GPa, 130 GPa, 140 GPa, 150 GPa, 160 GPa, 170 GPa, 180 GPa, 190 GPa or 200 GPa, preferably ≥100 GPa.

[0029] As a preferred embodiment of the present invention, the planar body comprises a solid plate.

[0030] And / or, the solid plate is a solid plate of uniform thickness, or the solid plate includes a first region and a remaining second region, the second region surrounding the first region, and the thickness of the solid plate in the first region is less than the thickness of the solid plate in the second region.

[0031] It should be noted that the present invention does not impose specific requirements or special limitations on the area of ​​the first and second regions of the solid plate, as long as the thickness of the solid plate in each region is different, so that its stiffness can be distributed in a gradient in the plane, thereby further optimizing the pressure field. Those skilled in the art can make adaptive selections and adjustments according to actual conditions.

[0032] As a preferred embodiment of the present invention, the elastic modulus E1 of the first elastic material layer is 0.5MPa-20MPa, such as 0.5MPa, 1MPa, 1.5MPa, 2MPa, 2.5MPa, 3MPa, 3.5MPa, 4MPa, 4.5MPa, 5MPa, 8MPa, 10MPa, 12MPa, 15MPa, 18MPa or 20MPa, and preferably 1MPa-5MPa.

[0033] And / or, the thickness of the first elastic material layer is 50μm-500μm, such as 50μm, 100μm, 150μm, 200μm, 250μm, 300μm, 350μm, 400μm, 450μm or 500μm, preferably 100μm-300μm.

[0034] And / or, the material of the first elastic material layer includes a soft polymer.

[0035] And / or, the material of the first elastic material layer includes at least one of silicone rubber, soft polyurethane elastomer, or nitrile rubber.

[0036] And / or, the elastic modulus E2 of the second elastic material layer is 0.5GPa-15GPa, such as 0.5GPa, 1GPa, 1.5GPa, 2GPa, 2.5GPa, 3GPa, 3.5GPa, 4GPa, 4.5GPa, 5GPa, 8GPa, 10GPa, 12GPa or 15GPa, preferably 2GPa-8GPa.

[0037] And / or, the thickness of the second elastic material layer is 100μm-500μm, such as 100μm, 150μm, 200μm, 250μm, 300μm, 350μm, 400μm, 450μm or 500μm, preferably 200μm-400μm.

[0038] And / or, the material of the second elastic material layer includes a rigid porous material and / or a rigid polymer.

[0039] And / or, the material of the second elastic material layer includes at least one of aluminum foam, high-density aluminum foam, copper foam, rigid polyurethane elastomer, or rigid epoxy resin.

[0040] And / or, a transition layer may be further included between the first elastic material layer and the second elastic material layer.

[0041] In this invention, the addition of a transition layer can further achieve a smooth gradient transition of pressure from the first elastic material layer to the second elastic material layer, effectively alleviate the sudden change in interlayer modulus, thereby further optimizing the uniformity of pressure distribution on the cell surface, avoiding local stress concentration, and improving the cycle stability and lifespan of the battery.

[0042] As a preferred embodiment of the present invention, the elastic modulus E3 of the transition layer is 100MPa-800MPa, such as 100MPa, 150MPa, 200MPa, 250MPa, 300MPa, 350MPa, 400MPa, 450MPa, 500MPa, 550MPa, 600MPa, 650MPa, 700MPa, 750MPa or 800MPa, etc., preferably 200MPa-500MPa.

[0043] And / or, the thickness of the transition layer is 50μm-200μm, such as 50μm, 80μm, 100μm, 120μm, 150μm, 180μm or 200μm, preferably 80μm-150μm.

[0044] And / or, the material of the transition layer includes at least one of engineering plastics, modified elastomers, or flexible ceramics.

[0045] It should be noted that the present invention does not impose specific requirements or special limitations on engineering plastics, as long as the elastic modulus E3 of the transition layer is 100MPa-800MPa. Those skilled in the art can make adaptive selections and adjustments according to actual conditions, such as polyetheretherketone (PEEK), polyamide (PA), etc.

[0046] It should be noted that the modified elastomer is not subject to specific requirements or special limitations in this invention. As long as the elastic modulus E3 of the transition layer is 100MPa-800MPa, it is acceptable. Those skilled in the art can make adaptive selections and adjustments according to actual conditions. For example, it can be a modified elastomer obtained by modifying silicone rubber and polyurethane by filling with fibers or particles (such as silicon carbide whiskers), such as a polyurethane / silicon carbide composite.

[0047] And / or, the housing includes at least one of aluminum-plastic film, aluminum alloy shell, or steel shell.

[0048] As a preferred embodiment of the present invention, the negative electrode active material in the negative electrode active material layer includes a silicon-based material, wherein the silicon-based material includes silicon-oxygen materials (SiO2). xThe silicon-based material is selected from at least one of the following: 0 < x ≤ 2), silicon-carbon composite material, or pure silicon material. The content of the silicon-based material is 5 wt% to 100 wt% based on the total mass of the negative electrode active material of 100 wt%, for example, 5 wt%, 15 wt%, 25 wt%, 35 wt%, 45 wt%, 55 wt%, 65 wt%, 75 wt%, 85 wt%, 95 wt%, or 100 wt%, preferably 10 wt% to 100 wt%.

[0049] And / or, the core is a stacked structure and / or a wound structure.

[0050] In a second aspect, the present invention also provides a method for preparing a silicon-based lithium-ion battery with a confinement component according to the first aspect, the method comprising the following steps: A constraint component is obtained by combining a constraint frame and an elastic buffer layer. The constraint component is disposed on the outside of the core and connected to the core. The elastic buffer layer is located between the core and the constraint frame and covers the core. The outer casing is placed on the outside of the constraint component and connected to the constraint frame to obtain a silicon-based lithium-ion battery with a constraint component.

[0051] As a preferred technical solution of the present invention, the first region of the constraint frame includes a plurality of conductive connection parts, and the constraint frame is connected to the core through the conductive connection parts. The method for preparing the conductive connection parts includes at least one of laser welding, ultrasonic welding or conductive silver paste bonding.

[0052] And / or, the edge of the constraint frame includes a connection area, through which the housing is connected to the constraint frame, the connection area including any one of an interlocking structure, a weld joint, or a flange, the interlocking structure including at least one of a groove, a rib, or a through hole.

[0053] And / or, the housing includes at least one of aluminum-plastic film, aluminum alloy shell, or steel shell.

[0054] In this invention, when the outer shell is an aluminum-plastic film, the edge of the rigid frame is provided with an interlocking structure. Through encapsulation injection molding or hot pressing, the packaging edge material of the aluminum-plastic film can fill and wrap the interlocking structure, forming an integrated packaging structure in which mechanical interlocking and airtight sealing coexist. When the outer shell is an aluminum alloy shell or a steel shell, the edge of the rigid frame is provided with a flange or weld joint. Through laser welding or electron beam welding, the frame and the outer shell are sealed and connected as one, forming a robust constraint-encapsulation integrated structure.

[0055] Thirdly, the present invention also provides an electrical device comprising a silicon-based lithium-ion battery with a constraint component as described in the first aspect, or a silicon-based lithium-ion battery with a constraint component prepared by the preparation method described in the second aspect.

[0056] Compared with the prior art, the present invention has at least the following beneficial effects: 1) The constraint component provided by this invention includes a rigid frame and an elastic buffer layer. The elastic buffer layer can convert the concentrated force of the rigid frame into a uniform surface pressure acting on the core surface, which can more effectively suppress the expansion of high-proportion silicon anodes (including up to 100% silicon anodes). The rigid frame also serves as a current collector, and its connection with the core realizes the integration of mechanical constraint and current collection, simplifies the structure, and optimizes the force / electricity / heat transfer path. The shell and the rigid frame are connected into an integrated structure, and the shell-constraint frame co-encapsulation enhances the overall integrity, reduces the weight, and is compatible with various shell encapsulation forms.

[0057] 2) The silicon-based lithium-ion battery with constraint components provided by the present invention has a longer cycle life; due to the use of lightweight design and fewer connection components, it has a higher energy density; the elastic buffer layer improves the pressure distribution on the core surface, reduces non-uniformity, and increases uniformity; the packaging compatibility is stronger; the integrated connection design avoids the problems of traditional tab pulling or solder joint fatigue failure, the rate of increase of interface contact resistance after cycling is reduced, and the interface stability is better. Attached Figure Description

[0058] Figure 1 This is a top view of a silicon-based lithium-ion battery with a constraint component provided in Embodiment 2 of the present invention.

[0059] Among them, 1-3003 aluminum alloy square hard shell; 2-carbon fiber composite material plate; 3-second elastic material layer; 4-intermediate transition layer; 5-first elastic material layer; 6-core; 7-conductive connection part. Detailed Implementation

[0060] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0061] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0062] Example 1 This embodiment provides a silicon-based lithium-ion battery with a constraint component. The silicon-based lithium-ion battery includes a core, an aluminum-plastic film, and a constraint component. The constraint component includes a set of relatively parallel 7075 aluminum alloy solid plates and an elastic buffer layer (a first elastic material layer and a second elastic material layer). The 7075 aluminum alloy solid plates are disposed on the outside of the core, the elastic buffer layer is located between the core and the 7075 aluminum alloy solid plates, and the aluminum-plastic film is disposed on the outside of the constraint component. The 7075 aluminum alloy solid plates are connected to the core through conductive connecting parts, and the aluminum-plastic film is connected to the 7075 aluminum alloy solid plates through grooves. The specific structure, composition, and parameters are shown in Table 1.

[0063] Table 1 This embodiment also provides a method for fabricating the silicon-based lithium-ion battery with the constraint component, the method comprising: A rigid frame consisting of two solid 7075 aluminum alloy plates is provided. Multiple weld points are laser-welded to the first area of ​​the surfaces of the two plates to serve as conductive connections. Continuous grooves are then punched into the edges. An elastic buffer layer is obtained by laminating silicone rubber and aluminum foam. This elastic buffer layer is then laminated onto the surfaces of the two 7075 aluminum alloy plates to form a constraint component. This constraint component is placed on both sides of the opposing surfaces of the core, with the elastic buffer layer positioned between the core and the two 7075 aluminum alloy plates, in contact with the core surface. The positive and negative electrodes are connected to the welding points on two 7075 aluminum alloy plates by laser welding to complete the integrated force-electric connection, realizing the dual functions of mechanical fastening and electrical conduction. The above-mentioned overall structure is then placed in an aluminum-plastic film forming bag for top and side sealing. During the packaging process, the PP layer of the aluminum-plastic film is melted by hot pressing and flows into the groove of the rigid frame edge of the 7075 aluminum alloy solid plate. After cooling, a strong mechanical interlock and airtight seal are formed. Then, electrolyte is injected to heat seal the air bag opening, resulting in a silicon-based lithium-ion battery with restraining components.

[0064] Example 2 This embodiment provides a silicon-based lithium-ion battery with a constraint component. Figure 1A simplified top view of a silicon-based lithium-ion battery with a constraint component provided in Embodiment 2 of the present invention is shown. The silicon-based lithium-ion battery includes a core 6, a 3003 aluminum alloy square hard shell 1, and a constraint component. The constraint component includes a set of relatively parallel carbon fiber composite material plates 2 and an elastic buffer layer (a first elastic material layer 5, an intermediate transition layer 4, and a second elastic material layer 3). The carbon fiber composite material plates 2 are disposed on the outside of the core 6, the elastic buffer layer is located between the core 6 and the carbon fiber composite material plates 2, and the 3003 aluminum alloy square hard shell 1 is disposed on the outside of the constraint component. The carbon fiber composite material plates 2 are connected to the core 6 through conductive connection parts 7, and the 3003 aluminum alloy square hard shell 1 is connected to the carbon fiber composite material plates 2 through welding joints. The specific structure, composition, and parameters are shown in Table 2.

[0065] Table 2 This embodiment also provides a method for fabricating the silicon-based lithium-ion battery with the constraint component, the method comprising: Two carbon fiber composite plates are provided. Multiple weld points are laser-welded into the first area of ​​the surface of the two carbon fiber composite plates to serve as conductive connections. Flanges are then provided at their edges. An elastic buffer layer is obtained by combining silicone rubber, polyurethane / silicon carbide composite, and rigid epoxy resin. The elastic buffer layer is then laminated onto the surface of the two carbon fiber composite plates to obtain a constraint component. The constraint component is placed on both sides of the opposite surface of the core, while the elastic buffer layer is located between the core and the two carbon fiber composite plates, and is in contact with the surface of the core. The positive and negative electrodes led out from the core are connected to the weld points on the two carbon fiber composite plates by laser welding to complete the integrated force-electric connection, achieving the dual functions of mechanical fastening and electrical conduction. The above-mentioned overall structure is then placed in a 3003 aluminum alloy square hard shell. The flanges of the rigid frame of the carbon fiber composite plates are welded and sealed to the edge of the shell opening by laser welding. Then, electrolyte is injected and the gas bag opening is heat-sealed to obtain a silicon-based lithium-ion battery with a constraint component.

[0066] Example 3 This embodiment provides a silicon-based lithium-ion battery with a constraint component. The silicon-based lithium-ion battery includes a core, an aluminum-plastic film, and a constraint component. The constraint component includes a set of relatively parallel 7075 aluminum alloy solid plates and an elastic buffer layer (a first elastic material layer and a second elastic material layer). The 7075 aluminum alloy solid plates are disposed on the outside of the core, the elastic buffer layer is located between the core and the 7075 aluminum alloy solid plates, and the aluminum-plastic film is disposed on the outside of the constraint component. The 7075 aluminum alloy solid plates are connected to the core through conductive connecting parts, and the aluminum-plastic film is connected to the 7075 aluminum alloy solid plates through grooves. The specific structure, composition, and parameters are shown in Table 3.

[0067] Table 3 This embodiment also provides a method for fabricating the silicon-based lithium-ion battery with the constraint component, the method comprising: A rigid frame consisting of two solid 7075 aluminum alloy plates is provided. Multiple weld points are laser-welded into the first area of ​​the surface of the two 7075 aluminum alloy plates to serve as conductive connections. Continuous grooves are then punched into the edges. An elastic buffer layer is obtained by combining a soft polyurethane elastomer and copper foam. The elastic buffer layer is then laminated onto the surface of the two 7075 aluminum alloy plates to obtain a constraint component. The constraint component is placed on both sides of the opposite surface of the core, while the elastic buffer layer is located between the core and the two 7075 aluminum alloy plates, and is in contact with the surface of the core. The positive and negative tabs of the core are connected to the welding points on two 7075 aluminum alloy plates by laser welding to complete the integrated force-electric connection, realizing the dual functions of mechanical fastening and electrical conduction. The above-mentioned overall structure is then placed in an aluminum-plastic film molding bag and sealed from the top and sides. During the sealing process, the PP layer of the aluminum-plastic film is melted by hot pressing and flows into the groove of the rigid frame edge of the 7075 aluminum alloy solid plate. After cooling, a strong mechanical interlock and airtight seal are formed. Then, electrolyte is injected and the air bag opening is heat-sealed to obtain a silicon-based lithium-ion battery with restraint components.

[0068] Example 4 This embodiment provides a silicon-based lithium-ion battery with a constraint component. The structure of the silicon-based lithium-ion battery differs from that of Embodiment 1 in that: the first elastic material layer is close to the core, is a polyurethane / alumina composite, has an elastic modulus of 18 MPa and a thickness of 150 μm, and the second elastic material layer is far from the core, is high-density aluminum foam, has an elastic modulus of 12 GPa and a thickness of 300 μm. The remaining structure, composition and parameters are consistent with those of Embodiment 1.

[0069] Example 5 This embodiment provides a silicon-based lithium-ion battery with a constraint component. The structure of the silicon-based lithium-ion battery differs from that of Embodiment 1 in that: the first elastic material layer is close to the core, made of silicone rubber with an elastic modulus of 4 MPa and a thickness of 150 μm; the second elastic material layer is far from the core, made of rubber-modified polypropylene with an elastic modulus of 30 MPa and a thickness of 300 μm; the remaining structure and parameters are consistent with those of Embodiment 1.

[0070] Example 6 This embodiment provides a silicon-based lithium-ion battery with a constraint component. The structure of the silicon-based lithium-ion battery differs from that of Embodiment 1 in that: the first elastic material layer is close to the core, is a soft polyurethane elastomer with an elastic modulus of 8 MPa and a thickness of 150 μm, and the second elastic material layer is far from the core, is aluminum foam with an elastic modulus of 1.5 GPa and a thickness of 300 μm. The remaining structure, composition and parameters are consistent with those of Embodiment 1.

[0071] Example 7 This embodiment provides a silicon-based lithium-ion battery with a constraint component. The structure of the silicon-based lithium-ion battery differs from that of Embodiment 1 in that: the first elastic material layer is close to the core, is a high-hardness polyurethane elastomer with an elastic modulus of 22 MPa and a thickness of 150 μm; the second elastic material layer is far from the core, is low-density polyethylene (LDPE) with an elastic modulus of 0.3 GPa and a thickness of 300 μm; the remaining structure, composition and parameters are consistent with those of Embodiment 1.

[0072] Example 8 This embodiment provides a silicon-based lithium-ion battery with a constraint component. The difference between the structure of the silicon-based lithium-ion battery and that of Embodiment 1 is that the thickness of the 7075 aluminum alloy solid plate is 4.0 mm, while the rest of the structure, composition and parameters are the same as those of Embodiment 1.

[0073] Comparative Example 1 This comparative example provides a silicon-based lithium-ion battery with a constraint component. The difference between the structure of the silicon-based lithium-ion battery and that of Example 1 is that the elastic buffer layer is replaced with a common PET insulating film (50 μm thick, without elastic buffer function), while the rest of the structure, composition and parameters are the same as those of Example 1.

[0074] This comparative example also provides a method for preparing the silicon-based lithium-ion battery with the aforementioned constraint components. The difference between this method and Example 1 is that the traditional welding tab method is used, there is no mechanical connection between the constraint frame and the core, and only limited constraints are applied through the outer shell. The remaining preparation methods and parameters are consistent with Example 1.

[0075] The silicon-based lithium-ion batteries with constraint components provided in Examples 1-8 and Comparative Example 1 were subjected to performance tests, specifically including: 1) Cycle performance test: At 25°C, the battery was charged at a constant current of 1C to 4.2V, then switched to constant voltage until the current dropped to 0.05C, and then discharged at a constant current of 1C to 3.0V. The initial discharge capacity was recorded, and this process was repeated 1000 times. The capacity retention rate was calculated as (1000th discharge capacity / initial discharge capacity × 100%); 2) Pressure distribution test: A micro pressure sensor matrix was implanted between the core and the elastic buffer layer. When the battery was charged to 50% SOC, the pressure at each point was recorded, and the pressure non-uniformity was calculated as (maximum pressure - minimum pressure) / average pressure; 3) Battery energy density calculation: The weight energy density (Wh / kg) of the entire battery, including the battery casing and constraint components, was calculated; 4) Interface resistance test: The internal resistance of the battery was tested before and after 1000 cycles using the AC impedance method, and the percentage increase in interface contact resistance was calculated.

[0076] The specific test results are shown in Table 4.

[0077] Table 4 The test results show that: (1) As can be seen from Examples 1-4 and Example 6, the silicon-based lithium-ion battery with constraint components provided by the present invention has an initial discharge capacity of 4.82Ah-5.23Ah, a battery energy density of 268Wh / kg-282Wh / kg, a pressure non-uniformity of 9.2%-16%, a capacity retention rate of 88.3%-92.5% after 1000 cycles, and an interface resistance increase of 7.5%-10.5% after cycling.

[0078] Further preferably, as can be seen from Examples 1-3 and Comparative Example 1, the cycle life is significantly improved: after 1000 cycles, the capacity retention rates of Examples 1-3 are all much higher than those of Comparative Example 1 (92.5%, 90.1%, and 88.3% for Examples 1-3, respectively, compared to 78.0% for Comparative Example 1). This fully demonstrates that the constraint component composed of a macroscopic rigid constraint framework combined with a gradient elastic buffer layer can effectively suppress the expansion of the silicon anode, slow down capacity decay, and significantly extend battery life, exhibiting excellent stability even for pure silicon anodes (Example 3).

[0079] The pressure distribution is extremely uniform: the pressure non-uniformity of Examples 1-3 is less than 13%, while that of Comparative Example 1 is as high as 58.5%. This directly verifies that the existence of the gradient elastic buffer layer can efficiently disperse the concentrated force of the rigid constraint frame into uniform surface pressure, avoiding excessive or insufficient local stress and ensuring the consistency of the constraint effect.

[0080] The battery energy density is significantly superior: the lightweight frame material and integrated design (the frame material simultaneously functions as a current collector, connecting with the current collector of the corresponding electrode in the core; the frame material is also integrated with the outer shell, achieving a unified integrated design) demonstrate that the battery energy densities of Examples 1-3 are all higher than those of Comparative Example 1. This shows that the present invention achieves a better constraint effect without sacrificing (or even improving) battery energy density.

[0081] The interface stability is greatly enhanced: the interface resistance growth in Examples 1-3 is much smaller than that in Comparative Example 1. This is due to the integrated force-electric connection design, which avoids the fatigue failure problem of traditional tabs under cyclic stress and maintains excellent and stable electrical contact.

[0082] Wide compatibility with packaging and materials: Examples 1 and 3 use aluminum-plastic film packaging, while Example 2 uses aluminum shell packaging. These examples respectively addressed the three different silicon content ratios of the negative electrodes in Examples 1-3 (medium, high, and all-silicon), achieving excellent and consistent results. This demonstrates that the pressure-constraining component of this invention has good packaging compatibility and adaptability to a full spectrum of silicon content.

[0083] (2) As can be seen from Examples 1, 5 and 7, the elastic modulus E1 of the first elastic material layer and the elastic modulus E2 of the second elastic material layer of the present invention can satisfy E2≥10×E1. The gradient design can ensure a smooth transition of mechanical pressure from the rigid frame to the core, thereby converting the concentrated force of the frame into a uniform surface pressure acting on the surface of the core, effectively avoiding stress concentration. Furthermore, by limiting the elastic modulus E1 of the first elastic material layer to 0.5MPa-20MPa and the elastic modulus E2 of the second elastic material layer to 0.5GPa-15GPa, the overall performance of the present invention can be better.

[0084] If E2 < 10 × E1 (Example 5), even if the elastic modulus E1 of the first elastic material layer is 0.5 MPa-20 MPa and the elastic modulus E2 of the second elastic material layer is 0.5 GPa-15 GPa, the modulus change of the gradient buffer layer will be too small, making it difficult to effectively convert the concentrated force of the rigid frame into uniform surface pressure acting on the core surface. This results in poor pressure dispersion and stress concentration, failing to fully leverage the advantages of this invention in improving pressure distribution uniformity and cycle life.

[0085] If E2 ≥ 10 × E1, but E1 and E2 exceed the range defined by this invention (E1 = 22 MPa > 20 MPa, E2 = 0.3 GPa < 0.5 GPa in Example 7), even if the gradient condition is met, the buffer layer material itself will be too soft or too hard and will not be able to work together. Its cycle life (72.0%) and interface stability (resistance increase of 35.0%) are even worse than those of Comparative Example 1, which did not adopt the gradient buffer layer scheme of this invention (78.0% and 26.0%, respectively). This fully demonstrates the criticality of the E1 and E2 parameter range defined by this invention for achieving excellent performance.

[0086] (3) As can be seen from Examples 1 and 8, the present invention adjusts the thickness of the planar body to 0.5mm-3.0mm, which can provide sufficient rigid constraints while taking into account the lightweight requirements of the battery system. If the thickness of the planar body is too thin, the rigidity of the constraint frame is insufficient, making it difficult to effectively suppress the expansion of the silicon anode; if the thickness of the planar body is too thick, although it can provide stronger constraints, it will unnecessarily increase the weight and volume of the battery, resulting in a decrease in the system energy density.

[0087] In summary, the constraint component provided by this invention includes a rigid frame and an elastic buffer layer. The elastic buffer layer converts the concentrated force of the rigid frame into uniform surface pressure acting on the core surface. The rigid frame also functions as a current collector, and its connection with the core integrates mechanical constraint and current collection, simplifying the structure and optimizing the force / electricity / heat transfer path. Connecting the outer shell and the rigid frame into an integrated structure enhances overall integrity and reduces weight. The silicon-based lithium-ion battery with constraint component provided by this invention has a longer cycle life, higher energy density, higher pressure distribution uniformity, stronger packaging compatibility, and better interface stability.

[0088] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A silicon-based lithium-ion battery with a constraint component, characterized in that, The silicon-based lithium-ion battery includes a core, a casing, and a constraint component. The constraint component includes a constraint frame and an elastic buffer layer. The constraint frame includes at least one set of relatively parallel planar bodies. The constraint frame is disposed on the outside of the core, the elastic buffer layer is located between the core and the constraint frame and covers the core, and the outer shell is disposed on the outside of the constraint component; The constraint frame is connected to the core, and the outer shell is connected to the constraint frame.

2. The silicon-based lithium-ion battery according to claim 1, characterized in that, The first region of the constraint frame includes a plurality of conductive connection parts, and the constraint frame is connected to the core through the conductive connection parts. And / or, the constraint frame further includes a connecting portion between the relatively parallel planar bodies for fixing the relatively parallel planar bodies; And / or, the edge of the constraint frame includes a connection area, through which the housing is connected to the constraint frame; And / or, the elastic buffer layer is located between the core and the planar body in the constraint frame.

3. The silicon-based lithium-ion battery according to claim 2, characterized in that, The core includes at least one single electrode group, which includes a positive electrode sheet, a separator, and a negative electrode sheet stacked together. The positive electrode sheet includes a positive current collector and a positive active material layer located on at least one side of the positive current collector. The negative electrode sheet includes a negative current collector and a negative active material layer located on at least one side of the negative current collector. The constraint frame is connected to the positive current collector and / or the negative current collector through the conductive connection portion. And / or, the connection area includes any one of an interlocking structure, a welded joint, or a flange, wherein the interlocking structure includes at least one of a groove, a rib, or a through hole; And / or, the elastic buffer layer includes a first elastic material layer and a second elastic material layer stacked together, the first elastic material layer being close to the core and the second elastic material layer being away from the core, and the elastic modulus E1 of the first elastic material layer and the elastic modulus E2 of the second elastic material layer satisfying E2≥10×E1.

4. The silicon-based lithium-ion battery according to claim 2, characterized in that, The total area of ​​the conductive connection portion accounts for 0.1%-30% of the area of ​​the first region; And / or, the planar body includes at least one of a solid plate, a frame, or a truss structure; And / or, the thickness of the planar body is 0.5mm-3.0mm; And / or, the material of the constraint frame includes at least one of aluminum alloy, titanium alloy, magnesium alloy or carbon fiber reinforced composite material; And / or, the Young's modulus of the constraint frame is ≥70 GPa.

5. The silicon-based lithium-ion battery according to claim 4, characterized in that, The planar body includes a solid plate; And / or, the solid plate is a solid plate of uniform thickness, or the solid plate includes a first region and a remaining second region, the second region surrounding the first region, and the thickness of the solid plate in the first region is less than the thickness of the solid plate in the second region.

6. The silicon-based lithium-ion battery according to claim 3, characterized in that, The elastic modulus E1 of the first elastic material layer is 0.5MPa-20MPa; And / or, the thickness of the first elastic material layer is 50μm-500μm; And / or, the material of the first elastic material layer includes a soft polymer; And / or, the elastic modulus E2 of the second elastic material layer is 0.5 GPa-15 GPa; And / or, the thickness of the second elastic material layer is 100μm-500μm; And / or, the material of the second elastic material layer includes a rigid porous material and / or a rigid polymer; And / or, a transition layer may be further included between the first elastic material layer and the second elastic material layer.

7. The silicon-based lithium-ion battery according to claim 6, characterized in that, The elastic modulus E3 of the transition layer is 100MPa-800MPa; And / or, the thickness of the transition layer is 50μm-200μm.

8. The silicon-based lithium-ion battery according to claim 3, characterized in that, The negative electrode active material layer includes a silicon-based material, which includes at least one of silicon-oxygen material, silicon-carbon composite material or pure silicon material. The content of the silicon-based material is 5wt%-100wt% based on the total mass of the negative electrode active material being 100wt%.

9. A method for preparing a silicon-based lithium-ion battery with a constraint component according to any one of claims 1-8, characterized in that, The preparation method includes the following steps: A constraint component is obtained by combining a constraint frame and an elastic buffer layer. The constraint component is disposed on the outside of the core and connected to the core. The elastic buffer layer is located between the core and the constraint frame and covers the core. The outer casing is placed on the outside of the constraint component and connected to the constraint frame to obtain a silicon-based lithium-ion battery with a constraint component.

10. An electrical appliance, characterized in that, The electrical device includes a silicon-based lithium-ion battery with a constraint component as described in any one of claims 1-8, or a silicon-based lithium-ion battery with a constraint component prepared by the preparation method as described in claim 9.

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