Composite electrode for solid-state battery, preparation method of composite electrode, battery cell for solid-state battery and solid-state battery

Abstract

The invention provides a composite electrode for a solid-state battery, a preparation method of the composite electrode, a battery cell for the solid-state battery and the solid-state battery, and particularly relates to the technical field of solid-state batteries. The composite electrode for the solid-state battery comprises a current collector; the active material layer is arranged on at least one side surface of the current collector; the solid electrolyte layer is arranged on the surface of one side, far away from the current collector, of the outer side of the active material layer; the solid electrolyte layer extends outwards in the circumferential direction of the active material layer so as to form a coating structure around the active material layer; and the solid electrolyte layer at the coating structure is in direct contact with the current collector. According to the composite electrode, a solid electrolyte layer structure with edge supporting and insulating effects is formed around the active material layer, so that direct contact between the active material and the edge of the current collector is avoided, and local short circuit is prevented. In addition, the extended solid electrolyte layer can also be used as a physical barrier, so that side reaction of an electrode interface is reduced, the cycle life of the battery is remarkably prolonged, and the safety performance of the battery is remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of solid-state battery technology, and in particular to a composite electrode for solid-state batteries and its preparation method, a battery cell for solid-state batteries, and a solid-state battery. Background Technology

[0002] Currently, most solid electrolyte layers are prepared using a transfer process: first, a solid electrolyte layer is formed by coating a substrate such as PET film or aluminum foil onto its surface, and then the solid electrolyte layer is transferred to the electrode sheet via a transfer method. However, this process has significant drawbacks: on the one hand, the process steps are cumbersome, resulting in low production efficiency, and the thinned areas of the electrode sheet cannot achieve effective transfer and composite of the solid electrolyte; on the other hand, the solid electrolyte layer and the electrode layer are in rigid contact, resulting in a large ion transport impedance at the interface, which accumulates continuously during battery cycling, leading to a gradual increase in the degree of polarization inside the battery and ultimately causing battery failure.

[0003] Meanwhile, solid-state battery electrode assembly often employs a stacking process. After stacking, significant pressure is typically applied through hot pressing or isostatic pressing to improve the solid-solid interface contact between the electrode and the solid electrolyte. However, external pressure can easily deform the positive electrode edge, thereby compromising the integrity of the solid electrolyte layer and increasing the risk of internal short circuits. To address this issue, existing technologies employ a method of fabricating a U-shaped resin frame at the electrode edge, using the resin frame for support and insulation. However, this method involves complex manufacturing processes, high precision control, and the introduction of foreign matter such as resin, which not only reduces battery production yield but also adversely affects the electrochemical performance of the cell, making it difficult to meet the demands of large-scale mass production.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a composite electrode for solid-state batteries and its preparation method, a cell for solid-state batteries, and a solid-state battery, aiming to solve at least one of the above-mentioned technical problems in the prior art.

[0006] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: A first aspect of the present invention provides a composite electrode for solid-state batteries, comprising: current collector; An active material layer is disposed on at least one surface of the current collector; A solid electrolyte layer is disposed on the surface of the active material layer away from the current collector; The solid electrolyte layer extends outward along the outer periphery of the active material layer to contact the current collector, thereby forming a coating structure around the active material layer.

[0007] Furthermore, the thickness of the solid electrolyte layer includes a first thickness and a second thickness; the first thickness is the thickness of the solid electrolyte layer above the active material layer; the second thickness is the thickness of the solid electrolyte layer at the coating structure; and the difference between the second thickness and the first thickness is the thickness of the active material layer.

[0008] Furthermore, the portion of the current collector extending beyond the solid electrolyte layer serves as a tab.

[0009] Preferably, the side with the tab is defined as the width direction of the composite electrode, and the direction perpendicular to it is defined as the length direction of the composite electrode.

[0010] The solid electrolyte layer forms two overhanging portions, W1 and W2, in the width direction of the active material layer; and two overhanging portions, L1 and L2, in the length direction.

[0011] Preferably, both W1 and W2 are greater than 0.

[0012] Preferably, W1 and W2 are each independently 0.5~5mm.

[0013] Preferably, both L1 and L2 are greater than 0.

[0014] Preferably, L1 and L2 are each independently 0.5~5mm.

[0015] Furthermore, the composite electrode includes a composite positive electrode and a composite negative electrode.

[0016] Preferably, the active material layer in the composite positive electrode is a positive electrode active material layer, and the active material layer in the composite negative electrode is a negative electrode active material layer; the width of the negative electrode active material layer is greater than the width of the positive electrode active material layer.

[0017] Preferably, the width difference ΔW between the negative electrode active material layer and the positive electrode active material layer is 1~20mm.

[0018] Preferably, the length difference ΔL between the negative electrode active material layer and the positive electrode active material layer is 1~20mm.

[0019] Preferably, the length difference △L = △L1 + △L2, △L1 > △L2; the electrode tabs are led out from the same side, △L1 is the difference value located on the side closer to the electrode tab, and △L2 is the difference value located on the side farther away from the electrode tab.

[0020] Furthermore, the thickness of the negative electrode active material layer is greater than the thickness of the positive electrode active material layer.

[0021] Preferably, the thickness of the negative electrode active material layer is 100~250μm.

[0022] Preferably, the thickness of the positive electrode active material layer is 100~200μm.

[0023] The second aspect of the present invention provides a method for preparing the composite electrode for solid-state batteries, wherein an active material slurry is coated on one or both surfaces of a current collector, followed by a solid electrolyte slurry, and after drying, an active material layer and a solid electrolyte layer are obtained, and finally the composite electrode for solid-state batteries is obtained by rolling.

[0024] Furthermore, the coating method of the active material layer includes gap coating, with each coating gap resulting in a composite electrode.

[0025] Preferably, during the coating process, the solid electrolyte layer has a reserved width on both sides of the current collector. The reserved width on one side is used to process the tab, and the reserved width on the other side is removed during cutting.

[0026] A third aspect of the present invention provides a cell for a solid-state battery, wherein the composite electrodes for the solid-state battery are stacked in a manner that alternates between positive and negative electrodes.

[0027] A fourth aspect of the present invention provides a solid-state battery, including the aforementioned solid-state battery cell.

[0028] Compared with the prior art, the present invention has at least the following beneficial effects: The composite electrode for solid-state batteries provided by this invention involves directly depositing a solid electrolyte layer on the outside of the active material layer and extending it outward along the circumference of the active material layer to form a coating structure. This coating structure is in direct contact with the current collector, forming a solid electrolyte layer structure around the active material layer that provides both edge support and insulation. This avoids direct contact between the active material and the edge of the current collector, preventing localized short circuits. Furthermore, the extended solid electrolyte layer also acts as a physical barrier, reducing the occurrence of side reactions at the electrode interface and significantly improving the cycle life and safety performance of the battery.

[0029] The preparation method provided by this invention enables the formation of an active material layer and a solid electrolyte layer in a single wet double-layer coating process during electrode manufacturing. This structure not only replaces the function of the traditional frame, preventing short circuits caused by edge damage during hot pressing or isostatic pressing, but also eliminates the steps of solid electrolyte transfer and separate frame installation, significantly simplifying the process and improving production efficiency.

[0030] The solid-state battery cell provided by this invention, based on the structural advantages of the aforementioned composite electrode, can form a tight solid-solid interface contact after stacking, effectively reducing ion transport impedance. Simultaneously, the surrounding solid electrolyte coating structure buffers external stress, reduces edge damage, and thus lowers the risk of short circuits. This design eliminates the need for additional bonding steps, simplifying the manufacturing process, improving manufacturing efficiency, and eliminating non-active components such as the adhesive frame, contributing to both extended battery cycle life and increased overall energy density.

[0031] The solid-state battery provided by this invention, given the advantages of the aforementioned battery cell, results in a solid-state battery with advantages such as high safety, high energy density, and long cycle life. Attached Figure Description

[0032] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0033] Figure 1 A front view of the composite electrode for solid-state batteries provided by the present invention; Figure 2 A side view of the composite electrode for solid-state batteries provided by the present invention; Figure 3 This is a schematic diagram showing the relationship between ΔL1 and ΔL2 between the negative electrode active material layer and the positive electrode active material layer. Figure 4 This is a front view of multiple composite electrodes obtained by gap coating according to the present invention; Figure 5 This is a side view of multiple composite electrodes obtained by gap coating according to the present invention; Figure 6 This is a schematic diagram of the structure of a solid-state battery cell provided by the present invention.

[0034] Explanation of key component symbols: 100 - Composite electrode for solid-state batteries; 110 - Current collector; 120 - Active material layer; 130 - Solid electrolyte layer; 200 - Composite positive electrode; 300 - Composite negative electrode. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0036] In the following, the terms “comprising,” “having,” and their cognates, which may be used in various embodiments of the invention, are intended only to indicate a particular feature, number, step, operation, element, component, or combination thereof, and should not be construed as excluding, firstly, the presence of one or more other features, numbers, steps, operations, elements, components, or combinations thereof, or adding the possibility of one or more features, numbers, steps, operations, elements, components, or combinations thereof.

[0037] According to a first aspect of the present invention, a composite electrode 100 for a solid-state battery is provided, the front view of which is shown below. Figure 1 As shown, it includes: a current collector 110; an active material layer 120 disposed on at least one side surface of the current collector 110; and a solid electrolyte layer 130 disposed on the active material layer 120 on the side surface away from the current collector 110. The solid electrolyte layer 130 extends outward along the outer periphery of the active material layer 120 to contact the current collector, thereby forming a covering structure around the active material layer 120.

[0038] The composite electrode 100 for solid-state batteries provided by this invention forms a covering structure by directly depositing a solid electrolyte layer 130 on the outside of the active material layer 120 and extending it outward in the circumferential direction of the active material layer 120. This covering structure is in direct contact with the current collector 110. The solid electrolyte layer 130 structure, which combines edge support and insulation, is formed around the active material layer 120, avoiding direct contact between the active material and the edge of the current collector 110 and preventing local short circuits. Furthermore, the extended solid electrolyte layer 130 can also act as a physical barrier, reducing the occurrence of side reactions at the electrode interface and significantly improving the cycle life and safety performance of the battery.

[0039] Since the active material layer 120 is encapsulated within the core layer composed of the current collector 110 and the solid electrolyte layer 130, therefore... Figure 1 The active material layer 120 cannot be directly observed from the front view; therefore, Figure 1 The specific location of the active material layer 120 is marked by a dashed line.

[0040] In some embodiments of the present invention, a side view of the composite electrode 100 for a solid-state battery is shown as follows. Figure 2 As shown, the current collector 110 serves as the base layer for current collection and support. Active material layers 120 are disposed on both its upper and lower surfaces. A solid electrolyte layer 130 is disposed on the outer side of the active material layer 120, away from the current collector 110. The solid electrolyte layer 130 extends outward along the circumference of the active material layer 120, forming a covering structure. At the covering structure (i.e., the edge region around the active material layer 120), the solid electrolyte layer 130 is in direct contact with the current collector 110 (e.g., at the edge region around the active material layer 120). Figure 2As shown, the electrolyte layer extends downward to and connects with the surface of the current collector 110.

[0041] The current collector 110 serves as the fundamental support carrier for the composite electrode, primarily functioning as both a physical support and an electron conductor. It provides a stable substrate for the active material layer 120, ensuring its firm fixation and structural integrity. Simultaneously, as an electron transport channel, the current collector 110 efficiently conducts electrons generated or consumed during the redox reaction of the active material layer 120 to the external circuit during battery charging and discharging, achieving directional electron flow, preventing electron accumulation within the electrode, and ensuring the continuous electrochemical reaction of the battery. Furthermore, its direct contact with the solid electrolyte layer 130 coating structure also helps maintain the overall stability of the electrode structure.

[0042] The active material layer 120 is the core functional layer of the composite electrode for electrochemical energy storage and conversion. During battery charge-discharge cycles, the active materials in the active material layer 120 complete the storage and release of charge carriers such as lithium ions through electrochemical reactions such as insertion / deintercalation and oxidation / reduction, directly determining key performance indicators such as battery capacity and energy density. Because it is positioned between the current collector 110 and the solid electrolyte layer 130, it can efficiently conduct electrons through the current collector 110 and maintain sufficient contact with the solid electrolyte layer 130, ensuring the smooth migration of charge carriers such as lithium ions between the two phases and providing the necessary conditions for electrochemical reactions.

[0043] The solid electrolyte layer 130 plays a triple role in ion conduction, interface isolation, and structural support. As the core channel for ion conduction, it selectively allows charge carriers such as lithium ions to migrate directionally between the active material layer 120 and the external electrode (or adjacent cell components), while blocking electrons from passing through, thus preventing internal short circuits. Covering the outside of the active material layer 120 and forming a coating structure, it isolates the active material layer 120 from the external environment, reduces side reactions between the active material and other components, and improves electrode stability. In addition, the surrounding coating structure can also provide support for the electrode edges during cell stacking and hot pressing, isostatic pressing, and other processes, preventing deformation of the active material layer 120 and the electrode as a whole, avoiding the risk of short circuits caused by structural damage, and further strengthening the structural integrity of the electrode through direct contact with the current collector 110.

[0044] It should be noted that the composite electrode 100 for solid-state batteries protected by this invention is not limited to lithium-ion solid-state batteries, but can also cover sodium-ion solid-state batteries and other solid-state battery types based on metal ion (such as potassium ion, magnesium ion, etc.) conduction. When the technical solution of this invention is applied to solid-state batteries of metal ions other than lithium-ion and sodium-ion, the specific types and compositions of the positive electrode active material, negative electrode active material and solid electrolyte involved in the aforementioned solution need to be adaptively adjusted according to the conduction characteristics and electrochemical performance requirements of the specific metal ions. This is to ensure that the ion deintercalation and intercalation capabilities of the positive electrode active material, the ion intercalation capability of the negative electrode active material and the ion conduction capability of the solid electrolyte are matched, thereby ensuring the electrochemical compatibility of the entire battery material system and the stable operation of the battery.

[0045] In some embodiments of the present invention, such as Figure 2 As shown, since the solid electrolyte forms a coating structure in some areas, the solid electrolyte layer 130 in the composite electrode has two thicknesses. The thickness of the solid electrolyte layer 130 includes a first thickness and a second thickness; the first thickness is the thickness of the solid electrolyte layer 130 above the active material layer 120, that is, the thickness of the area covering the top of the active material layer 120.

[0046] The second thickness is the thickness of the solid electrolyte layer 130 at the coating structure; the difference between the second thickness and the first thickness is the thickness of the active material layer 120, that is, in Figure 3 The total thickness from the surface of the current collector 110 to the top of the solid electrolyte layer 130.

[0047] Furthermore, the portion of the current collector 110 extending beyond the solid electrolyte layer 130 serves as a tab.

[0048] exist Figure 2 In this battery, the area of ​​the current collector 110 extending beyond the edge of the solid electrolyte layer 130 is used as a tab, which is an electrode in the battery used to connect to an external circuit. The tab is a key channel for current to flow into / out of the current collector 110 during battery charging and discharging, and is usually connected to external terminals by means of welding or other methods.

[0049] Preferably, the side with the tab is defined as the width direction of the composite electrode, and the direction perpendicular to it is defined as the length direction of the composite electrode.

[0050] In some embodiments of the present invention, such as Figure 1 As shown, the solid electrolyte layer 130 forms two overhanging portions, W1 and W2, in the width direction of the active material layer 120; and two overhanging portions, L1 and L2, in the length direction.

[0051] Preferably, both W1 and W2 are greater than 0, and the solid electrolyte layer 130 forms an insulating "barrier" or "moat" in the width direction. Even if the two electrodes are misaligned or squeezed during stacking, it is the insulating solid electrolyte layer 130 that contacts the adjacent electrode, rather than the conductive active material layer 120 directly contacting it, thus fundamentally avoiding the risk of short circuits. The fact that both W1 and W2 are greater than 0 improves current distribution and reduces interface impedance by increasing the ion transport interface area; it suppresses lithium dendrite growth by providing a mechanical barrier; and it provides the necessary alignment tolerance for the manufacturing process, improving manufacturing yield and the structural stability of the electrode.

[0052] Preferably, W1 and W2 are each independently 0.5~5mm.

[0053] Typically, but not limitingly, W1 and W2 can each be independently 0.5mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, or 5mm, or any value within the range of 0.5 to 5mm. "Independently" means that the values ​​of W1 and W2 are unrelated and have no dependency or constraint relationship. W1 can independently select a specific value within the 0.5 to 5mm range, and W2 can also independently select another value within the same range. The two values ​​do not need to be equal, and their specific values ​​can be determined according to actual process requirements, battery design needs, or performance optimization goals.

[0054] Preferably, both L1 and L2 are greater than 0.

[0055] Preferably, L1 and L2 are each independently 0.5~5mm. Typically, but not limitingly, L1 and L2 can each be 0.5mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm or 5mm, or any value within the range of 0.5~5mm.

[0056] It should be noted that if any of W1, W2, L1, or L2 exceeds 5mm, the excess portion will be trimmed in subsequent processes to meet the battery cell assembly requirements. This trimming not only directly results in the removal and discarding of the current collector substrate and solid electrolyte layer, causing material waste and increasing production costs, but also affects the battery cell's energy density, reducing the overall battery range and performance.

[0057] Furthermore, the composite electrode includes a composite positive electrode 200 and a composite negative electrode 300.

[0058] Preferably, the active material layer in the composite positive electrode 200 is a positive electrode active material layer, and the active material layer in the composite negative electrode 300 is a negative electrode active material layer; the width of the negative electrode active material layer is greater than the width of the positive electrode active material layer.

[0059] Preferably, the width difference ΔW between the negative electrode active material layer and the positive electrode active material layer is 1~20mm. It should be noted that the width direction here also conforms to the setting that "the side with the tab is defined as the width direction of the composite electrode, and the direction perpendicular to it is the length direction of the composite electrode."

[0060] Designing the width of the negative electrode active material layer to be greater than that of the positive electrode active material layer allows the negative electrode active material layer to fully cover the positive electrode active material layer laterally. This effectively avoids the "dendritic piercing" phenomenon that occurs when lithium dendrites generated on the positive electrode side grow towards the negative electrode side during battery charging and discharging, reducing the risk of internal short circuits. At the same time, a wider negative electrode active material layer can provide more space for lithium ions to intercalate, reducing the deposition of lithium ions on the negative electrode surface and improving the cycle stability and capacity retention of the battery.

[0061] Typical, but not restrictive, width difference ΔW can be, for example, 1mm, 2mm, 4mm, 8mm, 12mm, 16mm or 20mm, or any value in the range of 1 to 20mm.

[0062] Furthermore, the length of the negative electrode active material layer is greater than the length of the positive electrode active material layer.

[0063] Preferably, the length difference ΔL between the negative electrode active material layer and the positive electrode active material layer is 1~20mm.

[0064] Typical, but not restrictive, length difference ΔL can be, for example, 1 mm, 2 mm, 4 mm, 8 mm, 12 mm, 16 mm, or 20 mm, or any value in the range of 1 to 20 mm.

[0065] When the width difference △W is preferably greater than 20mm, the positive electrode active material layer and the negative electrode active material layer (size, capacity, etc.) are mismatched, which can easily lead to lithium plating or oxygen evolution, resulting in membrane puncture, short circuit or even fire and explosion; in terms of performance, the cell capacity is limited by the "short board", and the cycle life is shortened due to uneven reaction and low material utilization.

[0066] In some embodiments of the invention, such as Figure 3 As shown, the length difference △L = △L1 + △L2, △L1 > △L2; the electrode tabs are led out from the same side, △L1 is the difference value located on the side closer to the electrode tab, and △L2 is the difference value located on the side farther away from the electrode tab.

[0067] Setting the length difference ΔL1 near the tab to be greater than ΔL2 away from the tab has the following effects: Firstly, the tab side is the core area for electron conduction, and the current density is relatively higher during charging and discharging. A larger ΔL1 can reserve more structural space near the tab, avoiding excessive local stress, active material shedding, or damage to the solid electrolyte layer 130 caused by current concentration. At the same time, it provides more stable support for the connection between the tab and the current collector 110, improving the reliability of the connection between the electrode and the external circuit. Secondly, by setting ΔL1 and ΔL2 differently, it can ensure the structural strength and current conduction stability of the tab side, while avoiding the waste of active material or the redundancy of the overall electrode volume caused by an excessively large ΔL on the side away from the tab. While taking into account the electrode performance and structural stability, it can achieve the optimized design of the electrode size, which is more suitable for the spatial layout requirements when stacking cells.

[0068] Preferably, the thickness of the negative electrode active material layer is 100~250μm.

[0069] Preferably, the thickness of the positive electrode active material layer is 100~200μm.

[0070] Typically, but not limitingly, the thickness of the negative electrode active material layer can be, for example, 100 μm, 120 μm, 140 μm, 160 μm, 180 μm, 200 μm, 210 μm, 220 μm, 230 μm, 240 μm or 250 μm, or any value within the range of 100 μm to 250 μm; the thickness of the positive electrode active material layer can be, for example, 100 μm, 120 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm or 200 μm, or any value within the range of 100 μm to 200 μm.

[0071] The composite electrode includes a composite positive electrode 200 and / or a composite negative electrode 300.

[0072] Preferably, the current collector 110 of the composite positive electrode 200 is made of aluminum foil.

[0073] Preferably, the current collector 110 of the composite negative electrode 300 is made of copper foil.

[0074] The second aspect of the present invention provides a method for preparing the composite electrode 100 for solid-state batteries, wherein an active material slurry is coated on one or both surfaces of a current collector 110, followed by a solid electrolyte slurry, and after drying, an active material layer 120 and a solid electrolyte layer 130 are obtained, and finally the composite electrode 100 for solid-state batteries is obtained by rolling.

[0075] The preparation method provided by the present invention can form the active material layer and the solid electrolyte layer 130 at one time through wet double-layer coating during the production of the electrode. This structure not only replaces the function of the traditional rubber frame, preventing the short circuit caused by the edge breakage of the battery cell during the hot pressing or isostatic pressing process, but also eliminates the steps of solid electrolyte transfer printing and separately installing the rubber frame, significantly simplifying the process flow and improving the production efficiency.

[0076] In addition, this method effectively improves the problem of too high interfacial impedance caused by the solid-solid rigid contact between the solid electrolyte layer 130 and the electrode layer, which helps to improve the electrochemical performance and cycle stability of the battery. During the coating process, the active material and the solid electrolyte penetrate each other, and the solid electrolyte coats the surface and around the active material. The thickness of its two side edges and the spacing area is the sum of the thickness of the corresponding coating material area and the solid electrolyte layer 130. The edges of the positive and negative electrodes obtained by final cutting are both coated with solid electrolyte, with the same size, playing an insulating and supporting role during the rolling process, and converting the original rigid contact between the positive and negative electrodes and the solid electrolyte into the self-contact between the solid electrolytes.

[0077] In some embodiments of the present invention, the positive electrode active material slurry includes a positive electrode active material, a solid electrolyte, a first binder, and a solvent.

[0078] Preferably, the negative electrode active material slurry includes a negative electrode active material, a solid electrolyte, a second binder, and a solvent.

[0079] Preferably, the solid electrolyte slurry includes a solid electrolyte, a second binder, and a solvent.

[0080] If the solid-state battery is a lithium-ion solid-state battery, the specific selection of each component material can be as follows: The positive electrode active material includes: layered transition metal oxides, polyanion compounds, olivine-type compounds, and lithium-rich manganese-based materials, etc. Among them, typical examples of layered transition metal oxides are LiCoO2, NCM, and NCA; typical examples of polyanion compounds are LiFePO4, LiMnPO4, and Li3V2(PO4)2; olivine-type compounds are mainly lithium iron phosphate and its derivatives; typical examples of lithium-rich manganese-based materials are xLi2MnO3·(1-x)LiMO2 (M is a transition metal such as Ni, Co, Mn).

[0081] The negative electrode active material includes: carbon-based materials, silicon-based materials, titanium-based materials, and metallic lithium / lithium alloy materials, etc. Typical examples of carbon-based materials are natural graphite, artificial graphite, hard carbon, and soft carbon; typical examples of silicon-based materials are elemental silicon (nano-silicon powder, silicon nanowires), silicon-based composite materials (Si / C, SiO x , 12 / C, 0 < x < 2); typical examples of titanium-based materials are Li4Ti5O 12(LTO); Typical examples of lithium metal / lithium alloy materials are lithium metal foil, lithium-aluminum alloy, and lithium-tin alloy.

[0082] The solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes. Typical examples of polymer solid electrolytes are polyethylene oxide (PEO) based, polycarbonate (PC) based, and polyacrylonitrile (PAN) based polymer electrolytes (containing lithium salts such as LiPF6 and LiTFSI); typical examples of inorganic solid electrolytes are sulfide electrolytes (such as Li2S-P2S5, LLZO, and LGPS) and oxide electrolytes (such as Li3PO4 based and LiNbO3 based ceramic electrolytes); typical examples of composite solid electrolytes are polymer-inorganic particle composite electrolytes (such as PEO-LLZO composite electrolytes).

[0083] The first binder includes (typically used for bonding the positive electrode active material layer 120 to the current collector 110): polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyimide (PI), and water-based binders (such as a composite system of sodium carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR)).

[0084] The second binder includes (typically used for bonding the negative electrode active material layer 120 or the solid electrolyte layer 130, while also considering ion conduction compatibility): polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), polyvinyl alcohol (PVA), polyacrylic acid (PAA) and the above-mentioned CMC / SBR composite system. In some scenarios, polymers with good compatibility with solid electrolytes (such as PEO derivatives) can be selected.

[0085] The solvents include: N-methylpyrrolidone (NMP, commonly used to dissolve oily binders such as PVDF, suitable for the preparation of positive electrode slurries), deionized water (commonly used in aqueous binder systems, suitable for the preparation of negative electrode slurries or some environmentally friendly positive electrode slurries), dimethylformamide (DMF), dimethyl sulfoxide (DMSO) (which can be used as alternative or auxiliary solvents for NMP to adjust slurry viscosity); xylene (benzene derivatives), anisole (ether derivatives), and butyl butyrate (ester derivatives) (commonly used in sulfide solid electrolyte systems).

[0086] Furthermore, the coating method of the active material layer 120 includes gap coating, with each coating gap resulting in a composite electrode.

[0087] In one embodiment of the present invention Figure 4 This is a front view of multiple composite electrodes obtained by gap coating. Figure 5 This is a side view of multiple composite electrodes obtained by gap coating. (See image.) Figure 4 and Figure 5As shown, a double-layer coating method is adopted, and the coating operation is carried out on one or both sides of the current collector 110: First, an active material coating is formed on the surface of the current collector 110 in a gap coating manner, and the blank space between adjacent active material coatings is the reserved segmentation area for a single electrode; then, a solid electrolyte layer 130 is simultaneously coated on the active material coating to form a solid electrolyte layer 130 covering the active material coating. The coating process can select a single-strip coating or a multi-strip coating mode according to production needs.

[0088] Preferably, during the coating process, the solid electrolyte layer 130 has a reserved width on both sides of the current collector 110. The reserved width on one side is used to process the tab, and the reserved width on the other side is removed during cutting.

[0089] In the coating process of battery electrodes, the width and length directions of the electrodes are clearly defined: the width of the electrode corresponds to the MD (Machine Direction) of the coating machine, and the length of the electrode corresponds to the TD (Transverse Direction) of the coating machine. On both sides of the TD direction of the coating machine, the width of the current collector 110 needs to be reserved. This reserved width can be set to be equal or unequal. The reserved width of the current collector 110 on one side will be used in subsequent processing to form the tab, a key component for the battery to conduct current and connect to the external circuitry. The reserved width of the current collector 110 on the other side will be removed in subsequent production processes to ensure the electrode's dimensional accuracy and meet the requirements of subsequent processes such as battery assembly.

[0090] A third aspect of the present invention provides a cell for a solid-state battery, wherein the composite electrode 100 for a solid-state battery is formed by stacking the electrodes with positive and negative electrodes spaced apart.

[0091] The present invention relates to a solid-state battery cell, and based on the advantages of the aforementioned composite electrode, the prepared cell has the following advantages: First, after stacking, a continuous and tight solid-solid interface can be formed, which effectively avoids the problem of uneven bonding between the electrode and the independent solid electrolyte layer 130 in the traditional process, greatly reduces the interfacial ion transport impedance, and improves ion conduction efficiency.

[0092] Secondly, the solid electrolyte coating structure around the composite electrode can form a surrounding support after stacking. During the hot pressing or isostatic pressing of the cell, it can buffer the impact of external forces, prevent the deformation of the positive and negative electrode edges and the damage of the solid electrolyte layer, reduce the risk of internal short circuit from the source, and enhance the stability and safety of the cell structure.

[0093] Third, there is no need for separate alignment and bonding processes between the electrode and the solid electrolyte layer 130. The composite electrode can be directly stacked at intervals, which simplifies the stacking process, reduces the alignment accuracy requirements, and helps to improve production efficiency and control costs.

[0094] Fourth, the integrated structural design not only suppresses dendrite growth and interfacial side reactions during the cycling process through a stable interface, thus extending the cycle life of the battery cell, but also eliminates the need for traditional non-active insulating support components such as plastic frames, reducing the proportion of inactive materials. This allows for the inclusion of more active materials within the same volume, thereby increasing the energy density of the battery cell.

[0095] After completing the cutting process of composite positive electrode 200 and composite negative electrode 300, the wafers are stacked according to the positive and negative electrode spacing to finally assemble the battery cell (for specific stacking structure, please refer to...). Figure 6 In this process, the solid electrolyte layer 130 around the composite electrode plays a crucial dual role of insulation and support, thereby reducing the safety risk of internal short circuits caused by electrode deformation from the perspective of structural stability, and ensuring the structural integrity and safety of the cell.

[0096] A fourth aspect of the present invention provides a solid-state battery, including the aforementioned solid-state battery cell.

[0097] The solid-state battery provided by this invention, given the advantages of the aforementioned battery cell, results in a solid-state battery with advantages such as high safety, high energy density, and long cycle life.

[0098] The present invention is further illustrated below with specific embodiments. However, it should be understood that these embodiments are merely for illustrative purposes and should not be construed as limiting the invention in any way. Unless otherwise specified, the raw materials used in the embodiments of the present invention are produced under conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the reagents or instruments used are all commercially available conventional products.

[0099] Example This embodiment provides a solid-state battery, specifically including the following steps: 1. Preparation of composite cathode The ternary material (specifically NCM811), solid electrolyte (specifically Li6PS5Cl), VGCF, binder (specifically PVDF) and p-xylene are mixed by a dual planetary stirring process to obtain a positive electrode slurry, wherein the mass ratio of NCM811, solid electrolyte, VGCF and oily binder is 85:10:2:3.

[0100] A solid electrolyte (specifically Li6PS5Cl), a binder (specifically PVDF), and p-xylene are mixed to obtain a solid electrolyte slurry, wherein the mass ratio of the solid electrolyte to the oily binder is 97:3.

[0101] At a dew point temperature of -60℃, the active material slurry and the solid electrolyte slurry are separately pumped to a double-layer coating die and coated onto the current collector. After drying in a coating oven, a double-layer coated electrode is obtained. The active material layer is coated on the bottom layer through gaps, with a coating size of 95mm in the TD direction, 70mm in the MD direction, and a 4mm gap between uncoated areas, resulting in a thickness of 160μm. Simultaneously, the solid electrolyte is continuously coated on the top layer, with a coating width of 101mm, a thickness of 180μm at both edges, a thickness of 20μm in the upper material area, and a thickness of 180μm in the gap area.

[0102] The double-coated electrode sheet is rolled and die-cut to obtain a single composite positive electrode sheet with a length of 99 mm, a width of 74 mm, and a solid electrolyte width of 2 mm around the electrode sheet.

[0103] 2. Preparation of composite negative electrode The negative electrode material (specifically silicon-carbon material), solid electrolyte (specifically Li6PS5Cl), VGCF, aqueous binder (specifically styrene-butadiene rubber), and p-xylene are mixed to obtain a negative electrode slurry, wherein the mass ratio of silicon-carbon material, solid electrolyte, VGCF, and aqueous binder is 85:10:2:3.

[0104] A solid electrolyte (specifically Li6PS5Cl), an aqueous binder (specifically styrene-butadiene rubber), and p-xylene are mixed to obtain a solid electrolyte slurry, wherein the mass ratio of the solid electrolyte to the aqueous binder is 97:3.

[0105] At a dew point temperature of -60℃, the active material slurry and the solid electrolyte slurry are separately pumped to a double-layer coating die and coated onto the current collector. After drying in a coating oven, a double-layer coated electrode is obtained. The active material layer is coated on the bottom layer through gaps, with a coating size of 97 mm in the TD direction, 72 mm in the MD direction, and a 4 mm gap between uncoated areas, resulting in a thickness of 200 μm. Simultaneously, the solid electrolyte is continuously coated on the top layer, with a coating width of 101 mm, a thickness of 220 μm at both edges, a thickness of 20 μm in the upper material area, and a thickness of 220 μm in the gap area.

[0106] The double-coated electrode sheet is rolled and die-cut to obtain a single electrode sheet with a length of 99 mm, a width of 74 mm, and a solid electrolyte width of 1 mm around the electrode sheet.

[0107] 3. Stack the positive and negative composite electrode sheets into a cell, and assemble and package them to obtain the solid-state battery.

[0108] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A composite electrode for a solid-state battery, characterized by, The composite electrode comprises: a current collector; an active material layer disposed on at least one side surface of the current collector; a solid-state electrolyte layer disposed on the active material layer, away from the side surface of the current collector; the solid-state electrolyte layer extends outward along the outer periphery of the active material layer to contact the current collector, forming a cladding structure around the active material layer.

2. The composite electrode for solid-state batteries according to claim 1, characterized by The thickness of the solid-state electrolyte layer comprises a first thickness and a second thickness; the first thickness is the thickness of the solid-state electrolyte layer above the active material layer; the second thickness is the thickness of the solid-state electrolyte layer at the cladding structure; the difference between the second thickness and the first thickness is the thickness of the active material layer.

3. The composite electrode for solid-state batteries according to claim 1, characterized by The part of the current collector beyond the solid-state electrolyte layer serves as a tab; Preferably, the side provided with the tab is defined as the width direction of the composite electrode, and the direction perpendicular thereto is the length direction of the composite electrode; The solid-state electrolyte layer forms two overhanging parts in the width direction of the active material layer, which are W1 and W2, respectively; Two overhanging parts are formed in the length direction, which are L1 and L2, respectively; Preferably, W1 and W2 are both greater than 0; Preferably, W1 and W2 are each independently 0.5-5 mm; Preferably, L1 and L2 are both greater than 0; Preferably, L1 and L2 are each independently 0.5-5 mm.

4. The composite electrode for solid-state batteries according to claim 3, characterized by The composite electrode comprises a composite positive electrode and a composite negative electrode; Preferably, the active material layer in the composite positive electrode is a positive active material layer, and the active material layer in the composite negative electrode is a negative active material layer; Preferably, the width difference AW between the negative active material layer and the positive active material layer is 1-20 mm.

5. The composite electrode for solid-state batteries according to claim 4, characterized by The length of the negative active material layer is greater than the length of the positive active material layer; Preferably, the length difference AL between the negative active material layer and the positive active material layer is 1-20 mm; Preferably, the length difference AL = AL1 + AL2, AL1 > AL2; the tab is a same-side leading tab, AL1 is the difference on the side close to the tab, and AL2 is the difference on the side away from the tab.

6. The composite electrode for solid-state batteries according to claim 4, characterized by The thickness of the negative active material layer is greater than the thickness of the positive active material layer; Preferably, the thickness of the negative active material layer is 100-250 μm; Preferably, the thickness of the positive active material layer is 100-200 μm.

7. A method for producing the composite electrode for a solid-state battery according to any one of claims 1 to 6, characterized by, An active material slurry is coated on one side surface or both side surfaces of the current collector, followed by coating of a solid-state electrolyte slurry, drying to obtain an active material layer and a solid-state electrolyte layer, and finally rolling to obtain the composite electrode for solid-state batteries.

8. The preparation method according to claim 7, characterized in that, The coating method of the active material layer comprises gap coating, and each coating gap obtains a composite electrode; Preferably, the solid-state electrolyte layer has a reserved width on both sides of the current collector during coating, and the reserved width on one side is used for processing into a tab, and the reserved width on the other side is removed by cutting later.

9. An electrode for a solid-state battery, characterized by The composite electrode for solid-state batteries of any one of claims 1-6 is formed by interleaving the positive and negative electrodes.

10. A solid state battery, characterized by The solid-state battery cell core of claim 9 is included.

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