Composite current collector, battery cell, and solid-state battery

Abstract

The utility model provides a kind of composite current collector, battery and solid-state battery.The composite current collector includes: insulating layer, multiple through holes are equipped on insulating layer to form hollow area, along the thickness direction of insulating layer, hollow area has oppositely arranged first face and second face;First conductive layer, first face is equipped with first conductive layer;Second conductive layer, second face is equipped with second conductive layer, the projection area of first conductive layer and second conductive layer in insulating layer is less than the area of insulating layer, and the circumferential edge of first conductive layer and second conductive layer and the circumferential edge of insulating layer all have interval distance, so that insulating layer is formed with insulating frame at the outer periphery of first conductive layer and second conductive layer.The technical scheme of the utility model solves the problem that the composite current collector in the prior art is prone to burr during cutting, which can cause short circuit.

Description

Technical Field

[0001] This utility model relates to the field of secondary battery technology, and more specifically, to a composite current collector, a battery cell, and a solid-state battery. Background Technology

[0002] Compared to traditional rechargeable batteries, solid-state batteries have significant advantages in safety, energy density, and cycle performance. Bipolar stacking, a key technology for solid-state battery stacking, enables ultra-high voltage single-cell batteries to meet high power requirements. Copper-aluminum composite foil is one solution for this technology, with negative and positive electrodes arranged on both sides of the foil, combined with a solid electrolyte layer to form a bipolar battery. Utility Model Content

[0003] However, because copper-aluminum composite foil is relatively hard, it is prone to burrs during cutting, which can easily lead to short circuits and pose a safety risk.

[0004] The main objective of this invention is to provide a composite current collector, a battery cell, and a solid-state battery to solve the problem that burrs are easily generated during the cutting of composite current collectors in the prior art, which can lead to short circuits.

[0005] To achieve the above objectives, this utility model provides a composite current collector, comprising: an insulating layer having multiple through holes to form a hollow area, the hollow area having a first surface and a second surface arranged opposite to each other along the thickness direction of the insulating layer; a first conductive layer having a first conductive layer on the first surface; and a second conductive layer having a second conductive layer on the second surface, wherein the projected areas of the first conductive layer and the second conductive layer on the insulating layer are both smaller than the area of ​​the insulating layer, and the circumferential edges of the first conductive layer and the second conductive layer are spaced apart from the circumferential edge of the insulating layer, so that the insulating layer forms an insulating frame around the outer periphery of the first conductive layer and the second conductive layer.

[0006] In some embodiments, a buffer conductive layer is provided between at least one of the first conductive layer and the second conductive layer and the cutout area.

[0007] In some embodiments, the area of ​​the first conductive layer and / or the second conductive layer is equal to the area of ​​the buffer conductive layer.

[0008] In some embodiments, the buffer conductive layer includes at least one of nickel foil, tin foil, and titanium foil.

[0009] In some embodiments, a conductor is provided inside the through hole, and the first conductive layer is electrically connected to the second conductive layer through multiple conductors.

[0010] In some embodiments, the conductor is formed by extending at least one of a first conductive layer, a second conductive layer, and a buffer conductive layer in the via.

[0011] In some embodiments, a conductor is provided in the through hole, and the first conductive layer is electrically connected to the second conductive layer through a plurality of conductors. The conductor is formed by the first conductive layer and / or the second conductive layer extending in the through hole.

[0012] In some embodiments, one of the first conductive layer and the second conductive layer is an aluminum layer, and the other of the first conductive layer and the second conductive layer is a copper layer.

[0013] According to another aspect of the present invention, the present invention provides a battery cell comprising a plurality of battery cell units, wherein the battery cell unit comprises: the aforementioned composite current collector; a first electrode layer, wherein the first electrode layer is disposed on a first conductive layer; a second electrode layer, wherein the second electrode layer is disposed on a second conductive layer; and a solid electrolyte layer, wherein the solid electrolyte layer is disposed on the side of the first electrode layer and / or the second electrode layer opposite to the composite current collector.

[0014] In some embodiments, the projected area of ​​the solid electrolyte layer on the insulating layer is smaller than the area of ​​the insulating layer; and / or, the projected areas of both the first conductive layer and the second conductive layer on the solid electrolyte layer are smaller than the area of ​​the solid electrolyte layer.

[0015] According to another aspect of the present invention, the present invention provides a solid-state battery, including a housing and the aforementioned battery cell installed within the housing.

[0016] In some embodiments, the area S of the hollowed-out region satisfies the formula: S≥kRC / d; where S is the area of ​​the hollowed-out region in mm. 2 k is the overcurrent redundancy design factor, 1 < k ≤ 3; R is the maximum rate capability of the solid-state battery; C is the rated capacity of the solid-state battery, in Ah; d is the maximum allowable current per unit area of ​​material, in A / mm². 2 .

[0017] By applying the technical solution of this utility model, an insulating layer is used as a base, and a first conductive layer and a second conductive layer are respectively disposed on both sides of the insulating layer, with an insulating frame formed on the outer periphery of the first and second conductive layers. This has two advantages: firstly, the insulating layer can be cut to avoid cutting the first and second conductive layers, reducing the probability of burrs during cutting and thus reducing the probability of short circuits and safety risks; secondly, the insulating frame provides electronic and ionic insulation, eliminating the need for an additional ionic insulating layer, reducing processes and improving production efficiency. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an undue limitation of the present invention. In the drawings:

[0019] Figure 1 A schematic diagram of the insulating layer structure of one embodiment of the composite current collector of this utility model is shown;

[0020] Figure 2 It shows Figure 1 A cross-sectional view of the insulating layer;

[0021] Figure 3 It shows in Figure 1 A schematic diagram of a structure in which a first conductive layer is disposed on one side of an insulating layer;

[0022] Figure 4 It shows Figure 3 A sectional view;

[0023] Figure 5 It shows in Figure 3 A schematic diagram of a structure in which a buffer conductive layer is provided on the other side of the insulating layer;

[0024] Figure 6 It shows Figure 5 A sectional view;

[0025] Figure 7 It shows in Figure 5 A schematic diagram of the structure of a composite current collector formed by setting a second conductive layer on the buffer conductive layer;

[0026] Figure 8 It shows Figure 7 A cross-sectional view of the composite current collector;

[0027] Figure 9 A schematic diagram of the insulating layer structure of another embodiment of the composite current collector of this utility model is shown;

[0028] Figure 10 It shows in Figure 9 A schematic diagram of a structure in which a second conductive layer is disposed on one side of an insulating layer;

[0029] Figure 11 It shows in Figure 10 A schematic diagram of a structure in which a buffer conductive layer is provided on the other side of the insulating layer;

[0030] Figure 12 It shows in Figure 11 A schematic diagram of the structure of a composite current collector formed after the first conductive layer is set on the buffer conductive layer;

[0031] Figure 13 A schematic diagram of the insulating layer structure of another embodiment of the composite current collector of this utility model is shown;

[0032] Figure 14 It shows in Figure 13A schematic diagram of a structure in which buffer conductive layers are provided on both sides of an insulating layer;

[0033] Figure 15 It shows in Figure 14 A schematic diagram of a structure in which a second conductive layer is disposed on one side of the buffer conductive layer;

[0034] Figure 16 It shows in Figure 14 A schematic diagram of a composite current collector formed after the first conductive layer is set on the buffer conductive layer on the other side;

[0035] Figure 17 A schematic diagram of the structure of one embodiment of the battery cell of this utility model is shown;

[0036] Figure 18 A schematic diagram of another embodiment of the battery cell of this utility model is shown.

[0037] The above figures include the following reference numerals:

[0038] 10. Insulating layer; 11. Through hole; 21. First conductive layer; 22. Second conductive layer; 23. Buffer conductive layer; 31. First electrode layer; 32. Second electrode layer; 33. Solid electrolyte layer. Detailed Implementation

[0039] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0040] In existing technologies, copper-aluminum composite foils mostly use aluminum foil with copper plating. This process results in thicker copper-aluminum composite foils (currently generally over 25μm), which reduces the energy density of the battery cell. Ultra-thin copper-aluminum composite foils (less than 15μm) are more difficult to process and are not convenient to manufacture. In addition, in bipolar stacking, it is necessary to maintain ionic insulation between the positive and negative electrodes on both sides of the copper-aluminum composite foil. Therefore, an additional ionic insulating layer needs to be added between the upper and lower solid electrolyte layers of the copper-aluminum composite foil to prevent short circuits. This not only increases the thickness of the battery cell but also adds more processes, resulting in lower production efficiency.

[0041] Therefore, as Figures 1 to 16As shown, an embodiment of this utility model provides a composite current collector, comprising: an insulating layer 10, wherein the insulating layer 10 is provided with a plurality of through holes 11 to form a hollow area, and the hollow area has a first surface and a second surface disposed opposite to each other along the thickness direction of the insulating layer 10; a first conductive layer 21, wherein the first conductive layer 21 is provided on the first surface; and a second conductive layer 22, wherein the second conductive layer 22 is provided on the second surface. The projected areas of the first conductive layer 21 and the second conductive layer 22 on the insulating layer 10 are both smaller than the area of ​​the insulating layer 10. The circumferential edges of the first conductive layer 21 and the second conductive layer 22 are spaced apart from the circumferential edges of the insulating layer 10, so that the insulating layer 10 forms an insulating frame around the outer periphery of the first conductive layer 21 and the second conductive layer 22.

[0042] In the above technical solution, an insulating layer 10 is used as a base, and a first conductive layer 21 and a second conductive layer 22 are respectively disposed on both sides of the insulating layer 10. An insulating frame is formed on the outer periphery of the first conductive layer 21 and the second conductive layer 22. In this way, on the one hand, the insulating layer 10 can be cut to avoid cutting the first conductive layer 21 and the second conductive layer 22, thereby reducing the probability of burrs during cutting and thus reducing the probability of short circuits and reducing safety risks. On the other hand, the insulating frame can provide electronic and ionic insulation, eliminating the need to add an additional ionic insulating layer, thereby reducing processes and improving production efficiency.

[0043] Furthermore, compared to the copper plating process using aluminum foil in the prior art, in this application, the insulating layer 10 is used as the base, and the thickness of the first conductive layer 21 and the second conductive layer 22 is controlled. Since the insulating layer 10 has a lower density than the metal material, not only can the weight of the composite current collector be reduced, thereby increasing the energy density, but the processing technology is also simple and easy to process.

[0044] In some embodiments, the insulating layer 10 may be an insulating film, and the insulating film may be a perforated film.

[0045] In some embodiments, the insulating film described above is an ion-electron insulating film, including but not limited to PET (Polyethylene Terephthalate), PVC (Polyvinyl Chloride), PI (Polyimide), and PE (Polyethylene), which can provide an ultra-thin electroplating carrier while reducing the mass of the composite current collector and improving energy density. Figure 1 and Figure 2 As shown, the insulating film is perforated. The shape and size of the perforation (through hole 11) are not limited and can be circular, square, rhomboid, star-shaped, or strip-shaped.

[0046] It should be noted that the composite current collector in the embodiments of this utility model is a bipolar current collector.

[0047] In the mainstream aluminum foil copper plating process currently in use, copper and aluminum are in direct contact, which easily forms a galvanic cell, causing electrochemical corrosion and affecting cell performance. Therefore, as... Figures 1 to 16 As shown in the embodiment of this utility model, at least one of the first conductive layer 21 and the second conductive layer 22 is provided with a buffer conductive layer 23 between it and the hollow area.

[0048] With the above configuration, a buffer conductive layer 23 can be provided between the first conductive layer 21 and the second conductive layer 22, which can avoid electrochemical corrosion caused by direct contact between the first conductive layer 21 and the second conductive layer 22 (copper and aluminum).

[0049] In some embodiments, such as Figure 7 and Figure 8 As shown, a buffer conductive layer 23 is provided between the second conductive layer 22 and the hollow area.

[0050] In some embodiments, such as Figure 12 As shown, a buffer conductive layer 23 is provided between the first conductive layer 21 and the hollow area.

[0051] In some embodiments, such as Figures 14 to 16 As shown, a buffer conductive layer 23 is provided between the first conductive layer 21 and the second conductive layer 22 and the hollow area.

[0052] In some embodiments, such as Figure 16 As shown, the area of ​​the first conductive layer 21 and / or the second conductive layer 22 is equal to the area of ​​the buffer conductive layer 23.

[0053] The above configuration effectively avoids electrochemical corrosion caused by direct contact between the first conductive layer 21 and the second conductive layer 22 (copper and aluminum), thereby improving the long-term stability and service life of the composite current collector. Furthermore, while ensuring good conductivity, the overall weight of the composite current collector is further reduced because the buffer conductive layer 23 has the same area as the first conductive layer 21 and / or the second conductive layer 22, thus meeting electrical connection requirements. This prevents excessive increases in thickness or weight due to the addition of extra materials, effectively improving battery energy density.

[0054] In some embodiments, the buffer conductive layer 23 includes at least one of nickel foil, tin foil, and titanium foil.

[0055] Because of their inherent electrochemical stability, metals such as nickel, tin, and titanium can effectively avoid electrochemical corrosion caused by direct contact between copper and aluminum, ensuring the long-term stability of the composite current collector during battery charge-discharge cycles and significantly improving the battery's cycle life and overall performance.

[0056] like Figure 6 , Figure 8 and Figure 12 As shown in the embodiment of this utility model, a conductor is provided in the through hole 11, and the first conductive layer 21 is electrically connected to the second conductive layer 22 through multiple conductors.

[0057] In the above technical solution, by filling or setting a conductor in the through hole 11, the conductivity barrier caused by the insulation film isolation is effectively overcome, ensuring that the current can flow smoothly between the first conductive layer 21 and the second conductive layer 22, thus meeting the requirements of high-rate charging and discharging of the battery.

[0058] like Figure 6 , Figure 8 and Figure 12 As shown, in an embodiment of the present invention, the conductor is formed by any one of the first conductive layer 21, the second conductive layer 22 and the buffer conductive layer 23 extending in the through hole 11.

[0059] The above configuration not only simplifies the manufacturing process of the composite current collector, but also reduces problems such as poor contact or conductor detachment, ensuring a stable and efficient current transmission path between the first conductive layer 21 and the second conductive layer 22. Furthermore, since no additional materials are needed to form the conductor, material costs and processing steps are greatly reduced.

[0060] In this embodiment of the invention, one of the first conductive layer 21 and the second conductive layer 22 is an aluminum layer, and the other of the first conductive layer 21 and the second conductive layer 22 is a copper layer. This allows them to be connected to the positive and negative electrode materials respectively.

[0061] like Figures 17 to 18 As shown, an embodiment of this utility model provides a battery cell, including a battery cell unit. The battery cell unit includes: the aforementioned composite current collector; a first electrode layer 31, which is disposed on a first conductive layer 21; a second electrode layer 32, which is disposed on a second conductive layer 22; and a solid electrolyte layer 33, which is disposed on the side of the first electrode layer 31 and / or the second electrode layer 32 facing away from the composite current collector. This facilitates the subsequent formation of a bipolar battery cell.

[0062] In some embodiments, the first conductive layer 21 is an aluminum layer, preferably an aluminum foil; the second conductive layer 22 is a copper layer, preferably a copper foil; the first electrode layer 31 is made of a positive electrode material layer, and the second electrode layer 32 is made of a negative electrode material layer.

[0063] In some embodiments, the second conductive layer 22 is an aluminum layer, preferably an aluminum foil; the first conductive layer 21 is a copper layer, preferably a copper foil; the second electrode layer 32 is made of a positive electrode material layer, and the first electrode layer 31 is made of a negative electrode material layer.

[0064] The first conductive layer 21, the second conductive layer 22, the first electrode layer 31, the second electrode layer 32, and the solid electrolyte layer 33 undergo pressure processing to form a cell unit. These cell units are further stacked to complete the internal series connection, and then further pressure processed to form a bipolar cell. Solid electrolyte layers 33 are arranged on both the first electrode layer 31 and the second electrode layer 32 (positive and negative electrode layers). During pressure processing, the solid electrolyte layer 33 is prone to stress deformation, which can easily lead to contact between the solid electrolyte layer 33 on the first electrode layer 31 and the solid electrolyte layer 33 on the second electrode layer 32. This can easily cause a short circuit between the first electrode layer 31 and the second electrode layer 32. Therefore, if... Figures 17 to 18 As shown, in an embodiment of this utility model, the projected area of ​​the solid electrolyte layer 33 on the insulating layer 10 is smaller than the area of ​​the insulating layer 10.

[0065] With the above configuration, since the area of ​​the insulating layer 10 is larger than the area of ​​the solid electrolyte layer 33, the insulating layer 10 can exist at the edge of the solid electrolyte layer 33. That is, the solid electrolyte layer 33 deforms during the pressure treatment process, and the insulating layer 10 can also prevent the solid electrolyte layer 33 on the first electrode layer 31 and the solid electrolyte layer 33 on the second electrode layer 32 from contacting each other, thereby avoiding short circuit between the first electrode layer 31 and the second electrode layer 32 (positive and negative electrode layers).

[0066] like Figures 17 to 18 As shown, in the embodiments of this utility model, the projected areas of the first conductive layer 21 and the second conductive layer 22 on the solid electrolyte layer 33 are both smaller than the area of ​​the solid electrolyte layer 33.

[0067] With the above configuration, the battery can effectively avoid direct contact between the edges of the first conductive layer 21 and the edges of the second conductive layer 22 under high compression manufacturing process.

[0068] like Figures 17 to 18 As shown, the battery cell includes multiple battery cell units, which are stacked sequentially.

[0069] It should be noted that the battery cell is a bipolar cell.

[0070] The aforementioned battery cells possess all the advantages of the aforementioned composite current collectors, which will not be elaborated upon here.

[0071] An embodiment of this utility model provides a solid-state battery, including a housing and the aforementioned battery cell installed within the housing.

[0072] In the embodiments of this utility model, the area S of the hollowed-out region satisfies the formula: S≥kRC / d; where S is the area of ​​the hollowed-out region, in mm. 2 k is the overcurrent redundancy design coefficient, 1 < k ≤ 3 (this coefficient ensures the foil can continuously carry large currents without overheating or melting, guaranteeing the overcurrent design safety of the foil); R is the maximum rate of the solid-state battery; C is the rated capacity of the solid-state battery, in Ah; d is the maximum allowable current per unit area of ​​material (the maximum allowable current per unit area of ​​the buffer conductive layer within the through-hole 11 range), in A / mm. 2 .

[0073] In the above technical solution, the area S of the hollow region is determined according to the cell capacity ratio, thus ensuring the conductivity of the composite current collector. The selection of kRC / d effectively avoids overheating and melting caused by excessive current, protecting the composite current collector and ensuring its continuous safe operation, thereby improving battery reliability and lifespan. Furthermore, by calculating the hollow area, the conductivity efficiency of the current collector is ensured while reducing the overall weight of the composite current collector, which can improve battery energy density.

[0074] It should be noted that the area S of the hollowed-out area refers to the sum of the areas of all through holes 11.

[0075] The solid-state batteries described above possess all the advantages of the aforementioned battery cells, which will not be elaborated upon here.

[0076] This application also provides a method for preparing a composite current collector, comprising: performing a hollowing process on an insulating film to form a hollowed-out area; depositing a first conductive layer 21 on a first surface of the hollowed-out area and performing a protective treatment on the first conductive layer 21; and depositing a second conductive layer 22 on a second surface of the hollowed-out area. The protective treatment protects the coating from contamination during subsequent processing, keeping it clean.

[0077] In some embodiments, before depositing the second conductive layer 22 on the second side of the cutout area, a buffer conductive layer 23 is deposited on the second side of the cutout area, and then the second conductive layer 22 is deposited on the buffer conductive layer 23.

[0078] In some embodiments, before depositing the first conductive layer 21 on the first side of the cutout area, a buffer conductive layer 23 is deposited on the first side and the second side of the cutout area respectively, and the buffer conductive layer 23 on the first side is protected; a second conductive layer 22 is deposited on the buffer conductive layer 23 on the second side, and then the protection of the buffer conductive layer 23 on the first side is removed (i.e., the protective layer is removed), and then the first conductive layer 21 is deposited on the buffer conductive layer 23 on the first side.

[0079] The composite current collector of this application uses an insulating film as a substrate to plate copper and aluminum layers (first conductive layer 21 and second conductive layer 22). By controlling the plating thickness, the weight of the composite current collector is reduced, and the energy density is increased. The insulating film is a perforated film, and the perforation area is determined according to the cell capacity ratio to ensure the conductivity of the foil. A buffer conductive layer 23 exists between the copper and aluminum layers to avoid electrochemical corrosion caused by direct contact between the copper and aluminum layers. In the composite current collector, the size of the insulating film is larger than the size of the copper and aluminum layers, that is, there is an insulating border at the edge, which provides electronic and ionic insulation. There is no need to add an additional ionic insulating layer, reducing processes and improving production efficiency. Moreover, the cutting part of the composite current collector is an insulating film, which can avoid the short circuit problem caused by burrs generated when cutting the copper and aluminum metal layers.

[0080] In one specific embodiment, Figure 3 and Figure 4 In this process, an aluminum layer is deposited on one side of the insulating film. The method of aluminum deposition is not limited and can include vacuum evaporation, CVD vapor deposition (chemical vapor deposition), magnetron sputtering, or dielectric electroplating. The aluminum layer covers the other side of the insulating film and completely fills the hollow holes in the insulating film. After the deposition is completed, the side of the insulating film covered by the aluminum layer is protected to prevent contamination and keep it clean during subsequent processing. The protection method can be oiling or covering with a protective layer (such as PVC (Polyvinyl Chloride), PET (Polyethylene Terephthalate), PP (Polypropylene) film, etc.).

[0081] exist Figure 5 and Figure 6 In the process, a buffer conductive layer 23 is deposited on the other side of the insulating film. The deposition method is not limited and can be vacuum evaporation, CVD vapor deposition, magnetron sputtering or dielectric plating, etc. The material of the buffer conductive layer 23 can be at least one of stable metals such as nickel, tin and titanium, which isolates the copper and aluminum layers and avoids electrochemical corrosion.

[0082] like Figure 7 and Figure 8 As shown, copper is plated on the buffer conductive layer 23 of the insulating film. The plating method is not limited and can be vacuum evaporation, CVD vapor deposition, magnetron sputtering or dielectric plating, etc., to form a composite current collector.

[0083] In one specific embodiment, such as Figure 9 and Figure 10 As shown, a copper layer is plated on one side of the insulating film. The copper plating method is not limited and can be vacuum evaporation, CVD vapor deposition, magnetron sputtering, or dielectric plating, etc. The copper layer covers one side of the insulating film and completely fills the hollow holes in the insulating film. After the plating is completed, the side of the copper layer covering the insulating film is protected to prevent the copper layer from being contaminated in subsequent processing and to keep it clean. The protection method can be oiling or covering with a protective layer, etc.

[0084] like Figure 11 As shown, a buffer conductive layer 23 is deposited on the other side of the insulating film. The deposition method is not limited and can be vacuum evaporation, CVD vapor deposition, magnetron sputtering or dielectric plating, etc. The material of the buffer conductive layer 23 can be at least one of stable metals such as nickel, tin and titanium, which isolates the copper and aluminum layers and avoids electrochemical corrosion.

[0085] like Figure 12 As shown, aluminum is plated on the buffer conductive layer 23 of the insulating film. The plating method is not limited and can be vacuum evaporation, CVD vapor deposition, magnetron sputtering or dielectric plating, etc., to form a composite current collector.

[0086] In one specific embodiment, such as Figure 13 and Figure 14 As shown, a buffer conductive layer 23 is plated on both sides of the insulating film. The plating method is not limited and can be vacuum evaporation, CVD vapor deposition, magnetron sputtering, or dielectric plating. The material of the buffer conductive layer 23 can be at least one of stable metals such as nickel, tin, and titanium to isolate the copper and aluminum layers and prevent electrochemical corrosion. After the plating is completed, one side of the buffer conductive layer 23 is protected to prevent contamination in subsequent processing and keep it clean. The protection method can be oiling or covering with a protective layer.

[0087] like Figure 15 As shown, one side of the insulating film buffer conductive layer 23 is plated with copper. The copper plating method is not limited and can be vacuum evaporation, CVD vapor deposition, magnetron sputtering or dielectric plating, etc. After the plating is completed, one side of the copper layer is protected to protect the copper layer from contamination in subsequent processing and keep it clean. The protection method can be oiling or covering with a protective layer, etc.

[0088] like Figure 16 As shown, aluminum is plated on the other side of the insulating film buffer conductive layer 23. The plating method is not limited and can be vacuum evaporation, CVD vapor deposition, magnetron sputtering or dielectric plating, etc., to form a composite current collector.

[0089] like Figure 17 and Figure 18 As shown, a negative electrode layer is arranged on the copper-plated side of the composite current collector, and a positive electrode layer is arranged on the aluminum-plated side. A solid electrolyte layer is arranged on the negative electrode layer. The size of the solid electrolyte layer is larger than the size of the copper and aluminum layers but smaller than the size of the insulating film. After pressure treatment, a cell unit is formed. The cell units are further stacked to complete the internal series connection of the cell. After further pressure treatment, a bipolar cell is formed. There are positive and negative electrode layers on both sides of the composite current collector, and a solid electrolyte layer is arranged on both positive and negative electrode layers. During the pressure treatment, the stress deformation of the solid electrolyte layer is prone to contact, which can easily lead to a short circuit between the positive and negative electrode layers on both sides of the composite current collector. Because there is an insulating film at the edge, the contact of the solid electrolyte layer can be isolated, thus avoiding a short circuit between the positive and negative electrodes.

[0090] The positive electrode active material in the positive electrode material layer and / or the negative electrode active material in the negative electrode material layer can both be commonly used positive or negative electrode active materials in lithium-ion secondary batteries. For example, the positive electrode active material is selected from at least one of olivine structure lithium metal oxide, layered structure lithium metal oxide, and spinel structure lithium metal oxide, or the positive electrode active material is selected from one or more of lithium nickel cobalt manganese, lithium cobalt oxide, lithium nickel oxide, lithium nickel cobalt aluminum, lithium iron phosphate, and lithium-rich manganese-based materials; the negative electrode active material is selected from at least one of graphite, silicon, silicon oxide, silicon carbon, lithium titanate, lithium metal, and lithium alloys. The positive or negative electrode material layer can be formed by electrostatic spraying, slurry coating, or dry film pressing followed by lamination. The solid electrolyte includes, but is not limited to, one or more of sulfide solid electrolyte, halide solid electrolyte, oxide solid electrolyte, and polymer solid electrolyte. The solid electrolyte layer can be formed by electrostatic spraying, slurry coating, or dry film pressing followed by lamination.

[0091] To illustrate with specific data, the following examples are provided:

[0092] like Figure 1 and Figure 2 As shown, the insulating film is made of PET material, with a thickness of 5μm, a length of 500mm, and a width of 200mm. The insulating film is perforated, with a circular perforation shape, a diameter of 5mm, and a perforation area of ​​480mm×180mm.

[0093] like Figure 3 and Figure 4 As shown, an aluminum layer is deposited on one side of the insulating film with a hollow area. The aluminum deposition method is magnetron sputtering. The aluminum layer covers one side of the insulating film with a thickness of 5μm and completely fills the hollow area in the insulating film. After the deposition is completed, the aluminum layer covers the insulating film for protection. The protective layer covers the aluminum layer to protect the aluminum layer from contamination in subsequent processing, keep it clean, and facilitate good electrical contact with the electrode material.

[0094] like Figure 5 and Figure 6 As shown, a buffer conductive layer 23 is deposited on the other side of the insulating film. The deposition method is CVD vapor deposition. The material of the buffer conductive layer 23 is tin metal, and the deposition thickness is 2μm. It isolates the copper and aluminum layers and avoids electrochemical corrosion.

[0095] like Figure 7 and Figure 8 As shown, copper is plated on the buffer conductive layer 23 of the insulating film by vacuum evaporation, and the coating thickness is 5μm to form a composite current collector with a total thickness of 17μm.

[0096] like Figure 15As shown, a negative electrode layer is arranged on the copper-plated side of the composite current collector. The negative electrode material is silicon-carbon, with a size of 480mm × 180mm, and is arranged by slurry coating. A positive electrode layer is arranged on the aluminum-plated side. The positive electrode material is LiNi0.8Co0.1Mn0.1O2, with a size of 480mm × 180mm, and is arranged by dry film formation. A solid electrolyte membrane is arranged on the negative electrode layer. The solid electrolyte membrane is a sulfide solid electrolyte membrane with a size of 490mm × 190mm. The size of the solid electrolyte membrane is larger than the size of the positive and negative electrode layers. The distance between the edge of the solid electrolyte membrane and the edge of the positive and negative electrode layers is 5mm. The distance between the edge of the insulating film and the edge of the solid electrolyte membrane is 5mm. After pressure treatment at 180℃ and 300MPa for 10min, a cell unit is formed. The cell units are further stacked to complete the internal series connection of the cell. After further pressure treatment at 200℃ and 500MPa for 30min, a bipolar cell is formed.

[0097] It should be noted that the embodiments of this utility model provide a composite current collector, in which copper and aluminum are plated on a porous insulating film, and a buffer conductive layer is added between the copper and aluminum layers to avoid electrochemical corrosion caused by direct contact between copper and aluminum. Simultaneously, the presence of the insulating porous film can reduce the mass of the composite current collector and increase its energy density. In the composite current collector of this utility model, the size of the insulating film is larger than the size of the copper and aluminum layers, i.e., there is an insulating border at the edge, which can provide electronic and ionic insulation, eliminating the need for an additional ion insulating layer, reducing processes, and improving production efficiency.

[0098] As can be seen from the above description, the embodiments of this utility model achieve the following technical effects: Using an insulating layer as a base, a first conductive layer and a second conductive layer are respectively disposed on both sides of the insulating layer, and an insulating frame is formed on the outer periphery of the first and second conductive layers. In this way, on the one hand, the insulating layer can be cut to avoid cutting the first and second conductive layers, reducing the probability of burrs during cutting and thus reducing the probability of short circuits, thereby reducing safety risks; on the other hand, the insulating frame provides electronic and ionic insulation, eliminating the need for an additional ionic insulating layer, reducing processes, and thus improving production efficiency.

[0099] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A composite current collector, characterized in that, include: An insulating layer (10) is provided with a plurality of through holes (11) to form a hollow area. Along the thickness direction of the insulating layer (10), the hollow area has a first surface and a second surface that are arranged opposite to each other. A first conductive layer (21) is provided on the first surface; A second conductive layer (22) is provided on the second surface. The projected areas of the first conductive layer (21) and the second conductive layer (22) on the insulating layer (10) are both smaller than the area of ​​the insulating layer (10). The circumferential edges of the first conductive layer (21) and the second conductive layer (22) are spaced apart from the circumferential edge of the insulating layer (10) so that the insulating layer (10) forms an insulating frame on the outer periphery of the first conductive layer (21) and the second conductive layer (22).

2. The composite current collector according to claim 1, characterized in that, A buffer conductive layer (23) is provided between at least one of the first conductive layer (21) and the second conductive layer (22) and the hollow area.

3. The composite current collector according to claim 2, characterized in that, The area of ​​the first conductive layer (21) and / or the second conductive layer (22) is equal to the area of ​​the buffer conductive layer (23).

4. The composite current collector according to claim 2, characterized in that, The buffer conductive layer (23) includes at least one of nickel foil, tin foil and titanium foil.

5. The composite current collector according to claim 2, characterized in that, The through hole (11) is provided with a conductor, and the first conductive layer (21) is electrically connected to the second conductive layer (22) through a plurality of the conductors.

6. The composite current collector according to claim 5, characterized in that, The conductor is formed by extending at least one of the first conductive layer (21), the second conductive layer (22), and the buffer conductive layer (23) in the through hole (11).

7. The composite current collector according to claim 1, characterized in that, The through hole (11) is provided with a conductor, and the first conductive layer (21) is electrically connected to the second conductive layer (22) through a plurality of the conductors. The conductors are formed by the first conductive layer (21) and / or the second conductive layer (22) extending in the through hole (11).

8. The composite current collector according to any one of claims 1 to 7, characterized in that, One of the first conductive layer (21) and the second conductive layer (22) is an aluminum layer and the other is a copper layer.

9. A battery cell, characterized in that, It includes multiple battery cell units, wherein the battery cell unit includes: The composite current collector according to any one of claims 1 to 8; The first electrode layer (31) is provided on the first conductive layer (21); The second electrode layer (32) is provided on the second conductive layer (22); A solid electrolyte layer (33) is provided on the side of the first electrode layer (31) and / or the second electrode layer (32) away from the composite current collector.

10. The battery cell according to claim 9, characterized in that, The projected area of ​​the solid electrolyte layer (33) on the insulating layer (10) is smaller than the area of ​​the insulating layer (10); and / or, The projected areas of the first conductive layer (21) and the second conductive layer (22) on the solid electrolyte layer (33) are both smaller than the area of ​​the solid electrolyte layer (33).

11. A solid-state battery, characterized in that, Includes a housing and a battery cell as described in claim 9 or 10, mounted within the housing.

12. The solid-state battery according to claim 11, characterized in that, The area S of the hollowed-out region satisfies the following formula: S≥kRC / d; Where S is the area of ​​the hollowed-out region, in mm. 2 ; k is the overcurrent redundancy design coefficient, 1 < k ≤ 3; R represents the maximum rate capability of the solid-state battery; C represents the rated capacity of the solid-state battery, in Ah. d represents the maximum allowable current per unit area of ​​material, in A / mm². 2 .

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