Solid state battery stacked electrode packaging structure

Abstract

This application discloses a solid-state battery stacked electrode packaging structure, relating to the field of battery structure technology. It includes an electrode layer and current collectors attached to both sides thereon. The attachment surface of the current collector is provided with a number of protrusions. The surface of the protrusions has micropores. When the electrode layer and the current collector are hot-pressed, the protrusions embed into the electrode layer, so that the electrode layer and the current collector form a mechanical interlocking structure. The mechanical interlocking structure between the protrusions and the electrode layer on the current collector increases the adhesion between the current collector and the electrode layer. The micropores on the surface of the protrusions also have the effect of adsorbing electrode slurry, forming a physical interlock with the electrode layer, thereby preventing physical peeling between the current collector and the electrode layer.

Description

Technical Field

[0001] This application relates to the field of barium fluoride purification technology, specifically to a solid-state battery stacked electrode packaging structure. Background Technology

[0002] Solid-state battery stacked electrode packaging structure is a high-energy-density battery configuration formed by stacking positive electrode material, solid electrolyte layer and negative electrode material layer by layer. Its core feature is that the positive and negative electrode active materials collect electrons through current collectors (such as aluminum foil / copper foil) and realize ion transport through solid electrolyte.

[0003] However, during the charging and discharging process of this structure, the electrode active material (such as silicon-based materials, high-capacity ternary materials, etc.) undergoes significant volume expansion and contraction along with the insertion and extraction of lithium ions. This periodic, non-uniform volume change is transformed into repeated shear and tensile stresses between the rigidly contacting current collector and the electrode layer.

[0004] When the inherent interfacial adhesion force is unable to resist this stress, it will trigger localized adhesion failure, manifesting as micron- or millimeter-scale peeling and delamination of the current collector. This peeling phenomenon directly leads to three major cascading failures: First, there is the loss of electrical contact: the detached active material loses its electronic connection with the current collector, becoming "dead lithium," which leads to a rapid decline in the reversible capacity of the battery.

[0005] Second, the internal resistance surges: local contact failures interrupt or detour the electron transport path, significantly increasing the internal resistance of the entire cell and deteriorating the power characteristics.

[0006] Third, interfacial side reactions: newly exposed interfaces may react with the electrolyte and accelerate the uneven growth of lithium dendrites, further threatening safety.

[0007] Even more serious is that the inherent "solid-solid contact" characteristics of solid-state batteries, compared to the "solid-liquid immersion" contact of liquid batteries, result in greater interface stiffness, poor self-healing ability, and extremely low tolerance for volume changes. This further amplifies the aforementioned risks of stress concentration and delamination failure, exacerbates the risk of delamination failure, and severely restricts the cycle life of batteries, thus requiring urgent solutions. Utility Model Content

[0008] In order to overcome the above-mentioned technical problems, the purpose of this application is to provide a solid-state battery stacked electrode packaging structure to increase the adhesion between the current collector and the electrode layer and avoid the peeling of the current collector.

[0009] The objective of this application can be achieved through the following technical solutions: Specifically, a solid-state battery stacked electrode packaging structure is provided, including an electrode layer and current collectors attached to both sides thereon. The attachment surface of the current collector is provided with a number of protrusions, and the surface of the protrusions has micropores. When the electrode layer and the current collector are hot-pressed, the protrusions embed into the electrode layer to form a mechanical interlocking structure between the electrode layer and the current collector.

[0010] Several protrusions form a protrusion array on the adhesion surface of the current collector. During the hot pressing process between the electrode layer and the current collector, the protrusions in the protrusion array will embed into the electrode layer, thereby creating an anchoring effect between the current collector and the electrode layer, forming a mechanical interlock, and increasing the adhesion between the current collector and the electrode layer. The micropores on the surface of the protrusions also have the effect of adsorbing electrode slurry, forming a physical interlock with the electrode layer, thereby preventing physical peeling between the current collector and the electrode layer.

[0011] As a further embodiment of the present application: the electrode layer is composed of a positive electrode material layer, a solid electrolyte layer and a negative electrode material layer stacked sequentially, and a gradient cementing layer is also provided between the positive electrode material layer and the current collector.

[0012] The positive electrode material layer includes high-nickel ternary materials, lithium-rich manganese-based materials, or sulfur-based materials. These materials all have extremely high energy density, providing higher voltage and capacity. The solid electrolyte layer uses a solid electrolyte as the ion transport medium. Solid electrolytes are typically oxide, sulfide, or polymer-based electrolytes. Oxide, sulfide, and polymer solid electrolytes replace traditional flammable, explosive, and leak-prone organic liquid electrolytes, fundamentally eliminating the main risks of fire and explosion, and eliminating the leakage of liquid electrolytes. The negative electrode material layer uses lithium metal or silicon-based materials. Lithium metal has the highest specific capacity and the lowest electrode potential, which can significantly improve the battery's energy density.

[0013] As a further aspect of this application: the gradient adhesive layer is formed by spraying and bonding a first adhesive layer, a second adhesive layer and a third adhesive layer layer by layer, and the elastic modulus of the gradient adhesive layer is distributed from high to low from the current collector side to the electrode layer side.

[0014] The first adhesive layer is made of high-modulus conductive adhesive, using silver paste doped with carbon nanotubes, with an elastic modulus of 5-10 GPa, ensuring rigid bonding at the interface; the second adhesive layer is made of gradient modulus adhesive, using epoxy resin and graphene gradient composite, with an elastic modulus transitioning from 1 to 5 GPa; the third adhesive layer is made of low-modulus elastic adhesive, using silicone-based conductive adhesive, with an elastic modulus of 0.1-1 GPa, to accommodate electrode volume expansion. The first adhesive layer is "hard-connected" to the current collector, ensuring a strong bond and efficient stress transfer. The third adhesive layer is "soft-connected" to the cathode material layer, acting like a buffer to absorb strain energy, accommodate volume changes, and optimize the stress distribution between the current collector and the cathode material layer.

[0015] As for the space between the negative electrode material layer and the current collector, a gradient bonding layer may or may not be added as needed.

[0016] As a further aspect of this application: the thickness of the gradient cementing layer is 10 μm to 30 μm, and this thickness of gradient cementing layer minimizes the volume of the overall structure while maintaining stress buffering between the current collector and the positive electrode material layer.

[0017] As a further aspect of this application: the thickness of the gradient adhesive layer is less than the height of the protrusion, that is, after the gradient adhesive layer is set between the current collector and the positive electrode material layer, a root-like bond is formed. After the current collector and the positive electrode material layer are hot-pressed, the current collector, the gradient adhesive layer and the positive electrode material layer will directly form a triple protection mechanism of "physical anchoring + chemical bonding + stress buffering".

[0018] As a further aspect of this application: the current collector attached to the positive electrode material layer is an aluminum foil. Under high potential, a dense aluminum oxide passivation film will form on the surface of the aluminum foil corresponding to the positive electrode material layer, preventing the aluminum foil from being further oxidized and corroded, thereby maintaining the stability of the current collector.

[0019] As a further aspect of this application: the current collector attached to the negative electrode material layer is a copper foil, which is very stable at low potentials, does not form an alloy with lithium in the negative electrode material layer, and has excellent conductivity.

[0020] The beneficial effects of this application are: 1. In this application, the protrusion provided on the current collector attachment surface can be embedded into the electrode layer during the hot pressing of the current collector and the electrode layer, forming a mechanical interlocking structure with the electrode layer, which increases the adhesion between the current collector and the electrode layer and prevents physical peeling between the current collector and the electrode layer.

[0021] 2. When the protrusion is embedded in the electrode layer, the micropores on the surface of the protrusion can adsorb the electrode paste therein, thereby forming a physical interlock with the electrode and further improving the adhesion between the current collector and the electrode layer.

[0022] 3. By setting a gradient binder layer between the positive electrode material layer and the current collector, the overall mechanical compatibility and interface stability of the electrode structure are effectively improved. This gradient binder layer, through its continuous gradient modulus change, gradually and smoothly transfers the transverse shear stress generated by the volume expansion of the electrode layer during charging and discharging from the low-modulus layer (the side adjacent to the electrode layer) to the first binder layer (the side adjacent to the current collector), thereby achieving layer-by-layer stress dissipation and redistribution, greatly alleviating the stress concentration phenomenon at a single interface. Simultaneously, this gradient structure achieves a gradual transition of the thermal expansion coefficient between different material layers, gradually adjusting from the electrode layer to the current collector layer, significantly reducing interfacial thermal stress caused by temperature fluctuations and suppressing interlayer delamination. Attached Figure Description

[0023] The present application will be further described below with reference to the accompanying drawings.

[0024] Figure 1 This is a partial structural schematic diagram of a solid-state battery stacked electrode packaging structure according to this application; Figure 2 This is a partial structural schematic diagram of the current collector in a solid-state battery stacked electrode packaging structure of this application; Figure 3 yes Figure 2 A magnified view of a section at point A in the middle; Figure 4 This is a partial cross-sectional view of a solid-state battery stacked electrode packaging structure according to this application; Figure 5 yes Figure 4 A magnified view of a section at point B in the middle.

[0025] Explanation of reference numerals in the attached figures: 10, electrode layer; 11, positive electrode material layer; 12, solid electrolyte layer; 13, negative electrode material layer; 20, current collector; 21, protrusion; 22, micropore; 30, gradient adhesive layer; 31, first adhesive layer; 32, second adhesive layer; 33, third adhesive layer. Detailed Implementation

[0026] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] As one embodiment of this application, such as Figures 1-5As shown, a solid-state battery stacked electrode packaging structure is disclosed. The structure consists of an electrode layer 10 and current collectors 20 attached to both sides thereon. The electrode layer 10 consists of a positive electrode material layer 11, a solid electrolyte layer 12, and a negative electrode material layer 13. Therefore, the structure is formed by stacking the positive electrode material layer 11, the solid electrolyte layer 12, the negative electrode material layer 13, and the current collectors 20 located outside the positive electrode material layer 11 and the negative electrode material layer 13 in sequence and then forming them by hot pressing, thereby achieving the fusion between the layers. After the stacking is completed, the edges are sealed by hot pressing with an aluminum-plastic film to achieve the final product packaging.

[0028] In this embodiment, the positive electrode material layer 11 is composed of high-nickel ternary material, lithium-rich manganese-based material or sulfur-based material, the solid electrolyte layer 12 uses solid electrolyte as ion transport medium, and the solid electrolyte is usually such as oxide, sulfide or polymer-based electrolyte, and the negative electrode material layer 13 uses lithium metal or silicon-based material. The current collector 20 attached to the positive electrode material layer 11 is made of aluminum foil, and the current collector 20 attached to the negative electrode material layer 13 is made of copper foil.

[0029] See Figure 2 and Figure 3 In order to form a mechanical interlocking structure between the current collector 20 and the positive electrode material layer 11, an array of protrusions consisting of protrusions 21 is processed on the attachment surface of the current collector 20. The surface of the protrusions 21 has micropores 22. During the hot pressing process, the protrusions 21 are embedded into the positive electrode material layer 11, thereby creating an anchoring effect with the positive electrode material layer 11 and forming a mechanical interlock. At the same time, the micropores 22 also have the effect of adsorbing the electrode paste in the positive electrode material layer 11, forming a physical interlock. This structure can prevent physical peeling between the current collector 20 and the positive electrode material layer 11.

[0030] The above-mentioned array of protrusions composed of protrusions 21 can be formed on the attachment surface of the current collector 20 by a rolling microforming process. The principle is to use a steel roller with an engraved pattern to roll protrusions on the foil surface. The micropores 22 are formed by different processes depending on the material of the current collector 20. When the current collector 20 is aluminum foil, a porous alumina layer is generated in an acidic electrolyte through anodizing, thereby forming the micropores 22. When the current collector 20 is copper foil, the micropores 22 are generated by etching with NH4OH+H2O2 solution.

[0031] The mechanical interlock between the negative electrode material layer 13 and the current collector 20 is formed in the same way as that between the positive electrode material layer 11, and will not be described in detail here.

[0032] See Figure 4 and Figure 5A gradient binder layer 30 is also provided between the current collector 20 and the positive electrode material layer 11. The gradient binder layer 30 is formed by spraying and bonding a first binder layer 31, a second binder layer 32, and a third binder layer 33 layer by layer. The gradient modulus of the gradient binder layer 30 is distributed from high to low from the current collector 20 side to the electrode layer 10 side. The thickness of the gradient binder layer 30 ranges from 10 μm to 30 μm. Each layer is deposited layer by layer by spraying or scraping, but should be less than the height of the protrusion 21. The difference between the thickness of the protrusion 21 and the gradient binder layer 30 is preferably 3 μm to 7 μm, which can be set arbitrarily by those skilled in the art.

[0033] The gradient adhesive layer 30 forms a root-like bond with the protrusion 21 on the adhesion surface of the current collector 20. The gradient adhesive layer 30 is formed by spraying and bonding the first adhesive layer 31, the second adhesive layer 32 and the third adhesive layer 33 layer by layer.

[0034] After the gradient adhesive layer 30 is set, the transverse shear force generated by the volume expansion of the electrode layer 10 will be transmitted to the gradient adhesive layer 30. The gradient adhesive layer 30 transmits the stress from the third adhesive layer 33 (electrode layer 10 side) to the second adhesive layer 32 and the first adhesive layer 31 (current collector 20 side) through the elastic modulus gradient. This structure gradually adjusts the thermal expansion coefficient of each layer of material from the electrode to the electrolyte to reduce interfacial thermal stress.

[0035] The processing steps for the above structure include: First, a protrusion array composed of protrusions 21 is processed on the attachment surface of the current collector 20; Next, the gradient adhesive layer 30 is sprayed. The first adhesive layer 31 fills the gap (valley area) of the protrusion 21 to form a base bonding layer. The second adhesive layer 32 and the third adhesive layer 33 (1GPa→0.1GPa) cover the sidewall and top of the protrusion 21 to ensure that the total thickness of the gradient adhesive layer 30 is thinner than the height of the protrusion 21. Finally, the gradient adhesive layer 30 on the top of the protrusion 21 is compressed and thinned by the electrode layer 10 through hot pressing, so that the top of the protrusion 21 passes through the gradient adhesive layer 30 and is embedded in the electrode layer 10, so that a mechanical interlocking structure is formed between the current collector 20 and the electrode layer 10.

[0036] As one embodiment of this application, the first adhesive layer 31 is coated with a high-modulus conductive adhesive and uses silver paste doped with carbon nanotubes, with an elastic modulus of 5-10 GPa to ensure rigid bonding at the interface. The mass ratio of silver paste to carbon nanotubes can be adaptively adjusted by those skilled in the art to ensure that the elastic modulus of the obtained high-modulus conductive adhesive is within the range of 5-10 GPa.

[0037] The second adhesive layer 32 is coated with a gradient modulus adhesive, which is a gradient composite of epoxy resin and graphene with an elastic modulus transitioning from 1 to 5 GPa. The mass ratio of epoxy resin and graphene can be adjusted by those skilled in the art to ensure that the elastic modulus of the resulting gradient modulus adhesive is within the range of 1 to 5 GPa.

[0038] The third adhesive layer 33 is coated with a low-modulus elastic adhesive, using a silicone-based conductive adhesive with an elastic modulus of 0.1-1 GPa, to accommodate the volume expansion of the electrode layer 10. The type of silicone-based conductive adhesive can be arbitrarily selected by those skilled in the art, as long as the elastic modulus of the low-modulus elastic adhesive is within the range of 0.1-1 GPa.

[0039] As one embodiment of this application, a gradient bonding layer 30 may also be provided between the negative electrode material layer 13 and the current collector 20.

[0040] The foregoing has provided a detailed description of one embodiment of this application, but the description is merely a preferred embodiment and should not be construed as limiting the scope of this application. All equivalent variations and improvements made within the scope of this application should still fall within the patent coverage of this application.

Claims

1. A solid-state battery stacked electrode packaging structure, characterized in that, It includes an electrode layer (10) and a current collector (20) attached to both sides thereon. The attachment surface of the current collector (20) is provided with a number of protrusions (21). The surface of the protrusions (21) has micropores (22). When the electrode layer (10) and the current collector (20) are hot-pressed, the protrusions (21) embed into the electrode layer (10) so that the electrode layer (10) and the current collector (20) form a mechanical interlocking structure.

2. The solid-state battery stacked electrode packaging structure according to claim 1, characterized in that, The electrode layer (10) is composed of a positive electrode material layer (11), a solid electrolyte layer (12) and a negative electrode material layer (13) stacked in sequence. A gradient cementing layer (30) is also provided between the positive electrode material layer (11) and the current collector (20).

3. The solid-state battery stacked electrode packaging structure according to claim 2, characterized in that, The gradient adhesive layer (30) is formed by spraying and bonding the first adhesive layer (31), the second adhesive layer (32) and the third adhesive layer (33) layer by layer, and the elastic modulus of the gradient adhesive layer (30) is distributed from high to low from the current collector (20) side to the electrode layer (10) side.

4. The solid-state battery stacked electrode packaging structure according to claim 3, characterized in that, The elastic modulus of the first adhesive layer (31) is 5 GPa to 10 GPa, the elastic modulus of the second adhesive layer (32) is 1 GPa to 5 GPa, and the elastic modulus of the third adhesive layer (33) is 0.1 GPa to 1 GPa.

5. A solid-state battery stacked electrode packaging structure according to claim 2 or 3, characterized in that, The thickness of the gradient adhesive layer (30) is 10 μm to 30 μm.

6. A solid-state battery stacked electrode packaging structure according to claim 2 or 3, characterized in that, The thickness of the gradient adhesive layer (30) is less than the height of the protrusion (21).

7. A solid-state battery stacked electrode packaging structure according to claim 2, characterized in that, The current collector (20) attached to the positive electrode material layer (11) is an aluminum foil.

8. A solid-state battery stacked electrode packaging structure according to claim 2, characterized in that, The current collector (20) attached to the negative electrode material layer (13) is a copper foil.

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