Composite electrode tab and solid-state battery

Abstract

The application discloses a composite electrode tab and a solid-state battery. The composite electrode tab comprises a current collector and a separation layer. An electrode material coating and a first insulating coating are formed on at least one side surface of the current collector, wherein the first insulating coating is arranged around the electrode material coating. The separation layer is arranged in a stack with the electrode material coating and covers at least the electrode material coating. The first insulating coating is arranged around the circumferential edge of the electrode material coating. The separation layer and the first insulating coating form a double protection mechanism, so that effective physical isolation exists between the positive electrode tab and the negative electrode tab, direct contact between the two is avoided, and the safety performance of the battery is ensured.

Description

Technical Field

[0001] This utility model generally relates to the field of battery technology, and in particular to a composite electrode sheet and a solid-state battery. Background Technology

[0002] Solid-state battery cells typically consist of a positive electrode, a negative electrode, and a solid electrolyte layer, with the electrolyte layer positioned between the positive and negative electrodes. In the cell construction of a solid-state battery, the negative electrode is usually slightly larger than the positive electrode. This difference in electrode size is designed to meet the overall performance requirements of the battery; for example, optimizing the dimensions of the positive and negative electrodes can improve the energy density, cycle stability, and safety of the solid-state battery.

[0003] However, during the fabrication of solid-state batteries, such as in the high-pressure pressing process, the mismatch in size between the two electrodes can cause uneven shear forces to be applied to the solid electrolyte layer at the edge of the positive electrode. Under the action of shear forces, the edge of the positive electrode can lead to localized damage to the solid electrolyte layer, causing direct contact between the positive and negative electrodes and resulting in a short circuit in the battery. Utility Model Content

[0004] This utility model provides a composite electrode sheet, including a current collector and an insulating layer. An electrode material coating and a first insulating coating are formed on at least one side surface of the current collector, wherein the first insulating coating is disposed around the electrode material coating. The isolation layer is stacked on top of the electrode material coating and at least covers the electrode material coating.

[0005] As an alternative implementation, the insulating layer covers both the electrode material coating and the first insulating coating.

[0006] In one possible implementation, the current collector includes an electrode material region and a tab region located on one side of the electrode material region, wherein the first insulating coating and the electrode material coating are formed on the electrode material region. A second insulating coating is also formed on at least one side of the current collector, located in the tab region, with the edge of the second insulating coating in contact with the edge of the first insulating coating.

[0007] As an implementation method, the thickness of the first insulating coating is 10μm to 80μm, and / or the width of the first insulating coating is 3mm to 8mm.

[0008] As an implementation method, the thickness of the second insulating coating is 2mm to 5mm.

[0009] As one possible implementation, the first insulating coating is made of the same material as the second insulating coating, including two-dimensional inorganic materials and insulating elastomer materials. The two-dimensional inorganic material includes aluminum oxide and boehmite; the insulating elastomer material includes one or more of polyvinylidene fluoride, polyetherimide, polyvinyl chloride thermoplastic elastomer, polyolefin elastomer, polyester elastomer and polyamide thermoplastic elastomer, wherein the mass ratio of inorganic material to insulating elastomer is (80-90):(10-20).

[0010] As an alternative implementation, the thickness of the isolation layer is 2μm to 50μm, and / or the porosity of the isolation layer is 10% to 70%.

[0011] This utility model also provides a solid-state battery, including the above-mentioned composite electrode sheet, wherein the electrode sheet includes at least a positive electrode sheet.

[0012] As one possible implementation, the composite electrode sheet includes a positive electrode sheet, and the solid-state battery further includes a negative electrode sheet, wherein the negative electrode sheet does not include a first insulating coating and / or a separator layer, and the size of the positive electrode sheet is smaller than the size of the negative electrode sheet. There is a distance d3 between the edge of the negative electrode material coating on the negative electrode sheet and the outer edge of the first insulating coating on the positive electrode sheet, where 1mm≤d3≤3mm.

[0013] As an alternative implementation, when the composite electrode sheet includes a positive electrode sheet and a negative electrode sheet, the size of the positive electrode sheet is smaller than the size of the negative electrode sheet. There is a distance d1 between the outer edge of the first insulating coating on the negative electrode and the outer edge of the first insulating coating on the positive electrode, where 1mm≤d1≤6mm, and there is a distance d2 between the inner edge of the first insulating coating on the negative electrode and the inner edge of the first insulating coating on the positive electrode, where 2mm≤d2≤3mm.

[0014] In the above-described scheme, this application uses a first insulating coating to surround the circumferential edge of the electrode material coating. The first insulating coating covers the sharp edges of the electrode material coating, blunting them into slopes or rounded corners, thus preventing the sharp edges of the positive electrode from penetrating the solid electrolyte layer. Simultaneously, during high-pressure pressing, the shear force at the edge of the positive electrode acts first on the first insulating coating rather than being directly transmitted to the solid electrolyte layer. The plastic deformation of the first insulating coating absorbs some stress, preventing stress concentration and reducing the local shear strain of the solid electrolyte layer. Thus, during pressing, the edge of the positive electrode will not penetrate the solid electrolyte layer, and there is effective isolation between the positive and negative electrodes, preventing direct contact and ensuring battery safety. Alternatively, the isolation layer can completely cover the electrode material coating, or the electrode material coating and the first insulating coating, with the isolation layer completely covering the positive active material, blocking direct electron pathways and forming physical isolation, thereby suppressing direct contact between the positive and negative electrodes. When the shear force at the edge of the positive electrode breaks through the first insulating coating, the isolation layer continues to absorb the remaining energy through plastic deformation, preventing stress concentration and further reducing the local shear strain of the solid electrolyte layer. This separation layer and the first insulating coating form a dual protection mechanism, effectively isolating the positive and negative electrode plates and preventing them from coming into direct contact, thus ensuring the safety performance of the battery. Attached Figure Description

[0015] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a front view schematic diagram of the first type of positive electrode sheet provided in an embodiment of the present utility model; Figure 2 This is a front view schematic diagram of the first type of negative electrode sheet provided in the embodiment of this utility model; Figure 3 A cross-sectional schematic diagram of the first type of battery cell provided in this embodiment of the present utility model; Figure 4 A top view schematic diagram of the first type of battery cell provided in this embodiment of the utility model; Figure 5 This is a front view schematic diagram of the second type of positive electrode sheet provided in an embodiment of the present utility model; Figure 6 This is a front view schematic diagram of the second type of negative electrode sheet provided in an embodiment of the present utility model; Figure 7 A cross-sectional schematic diagram of the second type of battery cell provided in an embodiment of this utility model; Figure 8 A top view schematic diagram of the third type of battery cell provided in this embodiment of the utility model; Positive electrode 10, positive current collector 11, first part 101, second part 102, positive electrode material coating 12; Negative electrode sheet 20, negative electrode current collector 21, third part 201, fourth part 202, negative electrode material coating 22; First insulating coating 41, second insulating coating 42, and insulating layer 50. Detailed Implementation

[0016] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the relevant utility model and not intended to limit the scope of the utility model. Furthermore, it should be noted that, for ease of description, only the parts relevant to the utility model are shown in the accompanying drawings.

[0017] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0018] A solid-state battery cell typically consists of a positive electrode 10, a negative electrode 20, and a solid electrolyte layer, with the solid electrolyte layer positioned between the positive electrode 10 and the negative electrode 20. In the solid-state battery cell structure, the negative electrode 20 is usually slightly larger than the positive electrode 10. This difference in size between the positive electrode 10 and the negative electrode 20 is designed to meet the overall performance requirements of the battery; for example, optimizing the sizes of the positive electrode 10 and the negative electrode 20 can improve the energy density, cycle stability, and safety of the solid-state battery.

[0019] However, during the fabrication of solid-state batteries, such as in the high-pressure pressing process, the size of the negative electrode 20 is slightly larger than that of the positive electrode 10. This size mismatch can cause uneven shear forces to be applied to the solid electrolyte layer at the edges of the positive electrode 10. These shear forces, because their direction is perpendicular to the solid electrolyte layer, have extremely high destructive potential. As the pressing process continues, the edges of the positive electrode 10, under the action of shear forces, will gradually pierce into the solid electrolyte layer, even completely penetrating it, leading to localized damage to the solid electrolyte layer. Once the solid electrolyte layer is punctured, the effective isolation between the positive electrode 10 and the negative electrode 20 will be lost, resulting in direct contact.

[0020] In solid-state batteries, direct contact between the positive electrode 10 and the negative electrode 20 will trigger a violent redox reaction, i.e., a short circuit. A short circuit not only leads to a sharp decline in battery performance, but may also cause heat buildup inside the battery, and in severe cases, may even cause safety accidents such as fires or explosions.

[0021] Based on this, this application proposes a composite electrode sheet that can overcome the problem of direct contact between the positive electrode sheet 10 and the negative electrode sheet 20 caused by the shear force exerted on the solid electrolyte layer by the edge of the positive electrode sheet 10.

[0022] The composite electrode includes: a current collector, on at least one side of which an electrode material coating and a first insulating coating 41 are formed, wherein the first insulating coating 41 surrounds the electrode material coating. An insulating layer 50 is stacked with the electrode material coating and at least covers the electrode material coating.

[0023] refer to Figure 3 and Figure 7 Along the thickness direction of the current collector, the current collector has a first surface and a second surface arranged opposite to each other. Both the first surface and the second surface have an electrode material region and a tab region located on one side of the electrode material region. The main body region occupies a larger area on the first surface or the second surface, and the tab region occupies a smaller area on the first surface or the second surface.

[0024] The current collectors include positive electrode current collector 11 and negative electrode current collector 21. For example... Figure 3 As shown, the positive electrode 10 and the positive current collector 11 are correspondingly arranged. The positive current collector 11 can be one of aluminum foil, copper foil, or steel foil. Specifically, the aluminum foil can be one of microporous aluminum foil, etched aluminum foil, or composite aluminum foil; the copper foil can be one of microporous copper foil, etched copper foil, or composite copper foil; and the steel foil can be one of microporous steel foil or etched steel foil. Figure 1 As shown, a positive electrode material coating 12 is provided on the first portion 101 of the main body region of the positive electrode current collector 11. The positive electrode material coating 12 includes a positive electrode active material, a conductive agent, a solid electrolyte, and a binder. The positive electrode active material includes lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMn2O4), lithium iron phosphate (LiFePO4), lithium manganese iron phosphate (LiFeMnPO4), and lithium nickel cobalt manganese oxide (LiNiCoMnO2), etc. The main body region of the positive electrode current collector 11 also includes a second portion 102, which surrounds the first portion 101. A first insulating coating 41 is provided on the second portion 102, that is, the positive electrode material coating 12 is circumferentially provided with a first insulating coating 41.

[0025] Combination Figure 1 and Figure 3 As shown, an isolation layer 50 is stacked on the positive electrode current collector 11. The isolation layer 50 can cover the positive electrode material coating 12, or, combined with... Figure 5 and Figure 7 As shown, the insulating layer 50 can cover the positive electrode material coating 12 and the first insulating coating 41.

[0026] The negative electrode plate 20 is correspondingly arranged with the negative electrode current collector 21. For example... Figure 3 As shown, the negative electrode current collector 21 can be one of aluminum foil, copper foil, or steel foil. For example... Figure 2 As shown, a negative electrode material coating 22 is provided on the third part 201 of the main body region of the negative electrode current collector 21. The negative electrode material coating 22 includes a negative electrode active material, a conductive agent, a binder, and a solid electrolyte. The negative electrode active material includes graphite, silicon-based compounds, titanium-based compounds, alloy materials, and transition metal compounds. The main body region of the negative electrode current collector 21 also includes a fourth part 202, which surrounds the third part 201. A first insulating coating 41 is provided on the third part 201, that is, the negative electrode material coating 22 is provided with a first insulating coating 41 circumferentially.

[0027] Combination Figure 2 and Figure 3 As shown, an isolation layer 50 is stacked on the negative electrode current collector 21. The isolation layer 50 can cover the negative electrode material coating 22, or, combined with... Figure 6 and Figure 7 As shown, the insulating layer 50 can cover the negative electrode material coating 22 and the first insulating coating 41.

[0028] In one specific embodiment, the solid-state battery cell includes a positive electrode 10 and a negative electrode 20. The positive electrode 10 is the type described above, and the negative electrode 20 is a negative electrode as described in related technologies, meaning the negative electrode does not use the aforementioned negative electrode 20. The negative electrode does not include a first insulating coating, or it does not include a separator layer, or it does not include both a first insulating coating and a separator layer. For example, the negative electrode can be a conventional solid-state electrode or a conventional liquid-state electrode.

[0029] refer to Figure 3 As shown, in the positive electrode 10, since the first insulating coating 41 is disposed around the circumferential edge of the positive electrode material coating 12, the thickness of the first insulating coating 41 can match the thickness of the positive electrode material coating 12, or the thickness of the first insulating coating 41 can be less than the thickness of the positive electrode material coating 12, or the thickness of the first insulating coating 41 can be greater than the thickness of the positive electrode material coating 12. The first insulating coating 41 covers the sharp edge of the electrode material coating, blunting it into a slope or rounded corner, and inhibiting the sharp edge of the positive electrode 10 from penetrating the solid electrolyte layer. At the same time, during the high-pressure pressing process, the shear force of the edge of the positive electrode 10 acts on the first insulating coating 41 first rather than being directly transmitted to the solid electrolyte layer. The plastic deformation of the first insulating coating 41 can absorb some stress, avoid stress concentration, and thus reduce the local shear strain of the solid electrolyte layer. In this way, during the pressing process, the edge of the positive electrode 10 will not penetrate the solid electrolyte layer, and there is an effective isolation between the positive electrode 10 and the negative electrode 20, thereby avoiding direct contact between the two and ensuring the safety performance of the battery.

[0030] Furthermore, the separator 50 completely covers the positive electrode material coating 12, or the positive electrode material coating 12 and the first insulating coating 41. The separator 50 completely covers the positive electrode active material, blocking direct electron pathways and forming a physical barrier, thereby inhibiting direct contact between the positive electrode 10 and the negative electrode 20. When the edge shear force of the positive electrode 10 breaks through the first insulating coating 41, the separator 50 continues to absorb the remaining energy through plastic deformation, avoiding stress concentration and further reducing the local shear strain of the solid electrolyte layer. In this way, the separator 50 and the first insulating coating 41 form a dual protection mechanism, ensuring effective physical isolation between the positive electrode 10 and the negative electrode 20, preventing direct contact and guaranteeing the battery's safety performance.

[0031] It should be noted that, preferably, the insulating layer 50 completely covers the positive electrode material coating 12 and the first insulating coating 41.

[0032] Of course, it is understood that in another specific embodiment, the solid-state battery cell also includes a positive electrode 10 and a negative electrode 20, with the positive electrode 10 being the positive electrode 10 described above and the negative electrode 20 being the negative electrode 20 described above.

[0033] The first insulating coating 41 includes a two-dimensional inorganic material and an insulating elastomer material. The two-dimensional inorganic material includes, but is not limited to, aluminum oxide and boehmite. The insulating elastomer material includes, but is not limited to, one or more of polyvinylidene fluoride, polyetherimide, polyvinyl chloride thermoplastic elastomer, polyolefin elastomer, polyester elastomer and polyamide thermoplastic elastomer. The mass ratio of the inorganic material to the insulating elastomer material is (80-90):(10-20).

[0034] Two-dimensional inorganic materials constitute the majority of the composition. These materials provide support and effectively resist the shear stress at the edge of the positive electrode 10, preventing puncture of the solid electrolyte layer. The insulating elastomer material absorbs localized stress during the pressing process through plastic deformation, preventing stress concentration from being transferred to the solid electrolyte layer.

[0035] The material of the isolation layer 50 includes inorganic solid electrolyte, organic solid electrolyte, or a mixture of the two.

[0036] Optionally, combined Figure 1 and Figure 3 As shown, the thickness of the first insulating coating 41 is 10μm to 80μm, and / or the width of the first insulating coating 41 is 3mm to 8mm.

[0037] When the thickness of the first insulating coating 41 is 10 μm, the edge of the positive electrode 10 can be prevented from piercing the solid electrolyte layer during the pressing process. As the thickness of the first insulating coating 41 increases, it can further absorb some stress and avoid stress concentration. In practical applications, based on considerations of production cost and technical effect, the maximum thickness of the first insulating coating 41 is selected as 80 μm.

[0038] Similarly, when the width of the first insulating coating 41 is 3 mm, the edge of the positive electrode 10 can be prevented from piercing the solid electrolyte layer during the pressing process. As the width of the first insulating coating 41 increases, it can further absorb some stress and avoid stress concentration. In practical applications, based on considerations of production cost and technical effect, the maximum thickness of the first insulating coating 41 is selected to be 8 mm. Preferably, the width of the first insulating coating 41 is 4 mm to 6 mm.

[0039] Optionally, combined Figure 1 and Figure 3 As shown, the thickness of the insulating layer 50 is 2 μm to 50 μm. When the thickness of the insulating layer 50 is 2 μm, it can prevent the edge of the positive electrode 10 from piercing the solid electrolyte layer during the pressing process. Preferably, the thickness of the insulating layer 50 is 5 μm to 10 μm.

[0040] Optionally, the porosity of the isolation layer 50 is 10% to 70%. If the isolation layer 50 has a larger thickness, a smaller porosity can be selected, for example, 10%, 11%, 12%, 15%, or 20%, which can balance ionic conductivity and dendrite suppression ability. If the isolation layer 50 has a smaller thickness, a larger porosity can be selected, for example, 50%, 55%, 60%, 65%, or 70%, which can achieve ultra-high ion flux.

[0041] Optionally, a second insulating coating 42 is provided in the portion of the tab region near the electrode material region, and the edge of the second insulating coating 42 contacts the edge of the first insulating coating 41.

[0042] It should be noted that, in combination Figure 1 and Figure 5 As shown, during high-pressure pressing, the edge of the tab region is prone to shear force on the solid electrolyte layer due to abrupt changes in thickness. The second insulating coating 42 can further absorb some of the stress, avoid stress concentration, and thus further reduce the local shear strain of the solid electrolyte layer, preventing damage to the solid electrolyte layer.

[0043] The second insulating coating 42 is made of the same material as the first insulating coating 41. The thickness of the second insulating coating 42 is 2mm to 5mm. The thickness of the second insulating coating 42 matches the sum of the thickness of the first insulating coating 41 and the thickness of the positive electrode material coating 12, which helps the second insulating coating 42 absorb some stress. The width of the second insulating coating 42 can be 1mm to 2mm.

[0044] Optionally, in one specific embodiment, the solid-state battery cell includes a positive electrode 10 and a negative electrode 20, wherein the positive electrode 10 is the aforementioned positive electrode 10, and the negative electrode 20 is a negative electrode in the related art.

[0045] In the top view of the battery cell, as shown Figure 8 As shown, there is a gap d3 between the edge of the negative electrode material coating on the negative electrode sheet and the outer edge of the first insulating coating 41 on the positive electrode sheet 10, where 1mm≤d3≤3mm.

[0046] Optionally, in another specific embodiment, the solid-state battery cell includes a positive electrode 10 and a negative electrode 20, wherein the positive electrode 10 adopts the above-described positive electrode 10, and the negative electrode 20 adopts the above-described negative electrode 20.

[0047] In the top view of the battery cell, as shown Figure 4 As shown, there is a gap d1 between the outer edge of the first insulating coating 41 on the negative electrode 20 and the outer edge of the first insulating coating 41 on the positive electrode 10, where 1mm≤d1≤6mm, and there is a gap d2 between the inner edge of the first insulating coating 41 on the negative electrode 20 and the inner edge of the first insulating coating 41 on the positive electrode 10, where 3mm≤d2≤3mm.

[0048] It should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer" used above to indicate orientation or switching positional relationships are based on the orientation or switching positional relationships shown in the accompanying drawings. These are used solely for the convenience of describing this utility model and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "frame" and "layout" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "frame" or "layout" may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0049] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the utility model involved in this application is not limited to the technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A composite electrode sheet, characterized in that, include: A current collector having an electrode material coating and a first insulating coating (41) formed on at least one side surface, wherein the first insulating coating (41) is disposed around the electrode material coating; An isolation layer (50) is stacked with the electrode material coating and at least covers the electrode material coating.

2. The composite electrode sheet according to claim 1, characterized in that, The insulating layer (50) covers the electrode material coating and the first insulating coating (41).

3. The composite electrode sheet according to claim 1, characterized in that, The current collector includes an electrode material region and a tab region located on one side of the electrode material region. The first insulating coating (41) and the electrode material coating are formed on the electrode material region. A second insulating coating (42) located in the tab region is also formed on at least one side of the current collector surface, and the edge of the second insulating coating (42) is in contact with the edge of the first insulating coating (41).

4. The composite electrode sheet according to claim 3, characterized in that, The thickness of the first insulating coating (41) is 10 μm to 80 μm. And / or, the width of the first insulating coating (41) is 3mm to 8mm.

5. The composite electrode sheet according to claim 3, characterized in that, The thickness of the second insulating coating (42) is 2mm to 5mm.

6. The composite electrode sheet according to claim 3, characterized in that, The first insulating coating (41) and the second insulating coating (42) are made of the same material, including two-dimensional inorganic materials and insulating elastomer materials. The two-dimensional inorganic material includes aluminum oxide and boehmite; the insulating elastomer material includes one or more of polyvinylidene fluoride, polyetherimide, polyvinyl chloride thermoplastic elastomer, polyolefin elastomer, polyester elastomer and polyamide thermoplastic elastomer, wherein the mass ratio of inorganic material to insulating elastomer is (80-90):(10-20).

7. The composite electrode sheet according to claim 1, characterized in that, The thickness of the isolation layer (50) is 2μm~50μm. And / or, the porosity of the isolation layer (50) is 10% to 70%.

8. A solid-state battery, characterized in that, The composite electrode sheet according to any one of claims 1-7 includes at least a positive electrode sheet (10).

9. The solid-state battery according to claim 8, characterized in that, The composite electrode includes a positive electrode (10), and the solid-state battery also includes a negative electrode (20). The negative electrode (20) does not include a first insulating coating (41) and / or a separator (50). The size of the positive electrode (10) is smaller than that of the negative electrode. There is a distance d3 between the edge of the negative electrode material coating on the negative electrode sheet and the outer edge of the first insulating coating (41) on the positive electrode sheet (10), where 1mm≤d3≤3mm.

10. The solid-state battery according to claim 8, characterized in that, When the composite electrode sheet includes a positive electrode sheet (10) and a negative electrode sheet (20), the size of the positive electrode sheet (10) is smaller than the size of the negative electrode sheet (20). There is a distance d1 between the outer edge of the first insulating coating (41) on the negative electrode (20) and the outer edge of the first insulating coating (41) on the positive electrode (10), where 1mm≤d1≤6mm, and there is a distance d2 between the inner edge of the first insulating coating (41) on the negative electrode (20) and the inner edge of the first insulating coating (41) on the positive electrode (10), where 2mm≤d2≤3mm.

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