Composite co-assisting particles coated with a dopamine layer and a pvdf layer

Abstract

This invention discloses a composite conductive particle coated with a dopamine layer and a PVDF layer. The composite conductive particle comprises: a ceramic particle for guiding and dispersing lithium ions; a dopamine layer coated on the outer surface of the ceramic particle, the dopamine layer and the corresponding ceramic particle forming a primary and secondary composite particle; wherein the dopamine layer is composed of polydopamine molecules; and a PVDF layer coated on the outer surface of the secondary composite particle, the PVDF layer and the corresponding secondary composite particle forming the composite conductive particle; wherein the PVDF layer is composed of PVDF.

Description

Technical Field

[0001] This invention relates to the field of battery cathode particle technology, and in particular to a composite conductive particle coated with a dopamine layer and a PVDF layer. Background Technology

[0002] A battery is mainly formed by placing a positive electrode and a negative electrode in an electrolyte. In conventional technology, ceramic particles are added to the negative electrode to increase ionic conductivity. Ceramic particles have high ionic conductivity for lithium ions. Therefore, when lithium ions pass through the negative electrode, the dispersed ceramic particles guide the lithium ions, thus allowing for a uniform distribution of lithium ions within the positive electrode. However, conventional ceramic particles have a large number of alkaline groups (such as OH- and Li2O) on their surface. Therefore, during the manufacturing process, when multiple conventional ceramic particles are added to the positive electrode slurry, these alkaline groups react with the solvent in the slurry, making the slurry strongly alkaline. This causes degradation of both the positive electrode particles and the slurry, increasing the difficulty of the manufacturing process and potentially resulting in electrochemical properties of the produced positive electrode plate that are not as expected. Current technology includes methods to coat traditional ceramic particles with a dopamine layer for protection. However, this dopamine layer cannot completely cover the outer surface of the ceramic particles, leaving a small portion of the particle surface exposed. Furthermore, in conventional technology, when multiple dopamine-coated ceramic particles are added to the positive electrode slurry, the exposed areas of the secondary composite particles react with the solvent in the positive electrode slurry, making the positive electrode slurry highly alkaline.

[0003] Therefore, this application aims to propose a novel composite conductive particle coated with a dopamine layer and a PVDF layer to overcome the aforementioned deficiencies in the prior art. Summary of the Invention

[0004] Therefore, the purpose of this case is to solve the aforementioned problems in the prior art. This case proposes a composite conductive particle coated with a dopamine layer and a PVDF layer. The PVDF layer is then coated on the outer surface of the ceramic particle originally coated with the dopamine layer as a protective layer. This allows the PVDF layer to further protect the internal secondary composite particle and prevent it from reacting with the solvent in the positive electrode slurry, thus preventing the deterioration of the positive electrode slurry.

[0005] To achieve the above objectives, this invention proposes a composite conductive particle coated with a dopamine layer and a PVDF layer, wherein the composite conductive particle is disposed within a slurry layer of an electrode; the composite conductive particle comprises: a ceramic particle with high ionic conductivity for lithium ions; therefore, when lithium ions pass through the electrode, the ceramic particle guides and disperses the lithium ions, thereby forming a uniformly distributed lithium ion channel within the electrode; a dopamine layer coating the outer surface of the ceramic particle, the dopamine layer and the corresponding ceramic particle forming a primary and secondary composite particle; wherein the dopamine layer is composed of polydopamine molecules; and a PVDF layer coating the outer surface of the secondary composite particle, the PVDF layer and the corresponding secondary composite particle forming a primary and secondary composite particle. The particles form the composite conductive particles; the PVDF layer is composed of PVDF; the dopamine layer does not completely cover the outer surface of the ceramic particles, so a small portion of the ceramic particle surface remains exposed; therefore, the PVDF layer partially contacts the ceramic particle surface and partially contacts the dopamine layer; in the PVDF, some of the fluoride ions form ionic bonds with the lithium ions on the corresponding ceramic particle surface to form lithium fluoride; and another portion of the fluoride ions in the PVDF form hydrogen bonds with the nitrogen ions of the polydopamine molecules on the surface of the secondary composite particles, thus the PVDF forms a PVDF layer covering the outer surface of the secondary composite particles.

[0006] The features and advantages of this work will be further explained in the following description; please refer to the accompanying drawings while reading. Attached Figure Description

[0007] Figure 1 This shows a cross-sectional view of the structure of this case.

[0008] Figure 2 This example demonstrates the application of this case.

[0009] Among them, there is electrode 10, electrode substrate 11, electrode paste 12, electrode paste layer 13, ceramic particles 15, dopamine layer 35, PVDF layer 41, composite conductive particles 100, and secondary composite particles 110. Detailed Implementation

[0010] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0011] Please refer to Figures 1 to 2As shown, the composite conductive assistant particles coated with a dopamine layer and a PVDF layer in the present case are mainly used in the electrode 10 of a solid-state or quasi-solid-state battery. In application, a plurality of the composite conductive assistant particles 100 can be disposed inside the electrode 10, and the electrode 10 is particularly a positive electrode of the solid-state or quasi-solid-state battery. The particle size of the composite conductive assistant particles 100 is less than 300 nanometers. The electrode 10 includes an electrode substrate 11, which is a carrier plate for carrying the materials of the electrode 10; an electrode slurry layer 13 is coated on the electrode substrate 11, the electrode slurry layer 13 includes an electrode slurry 12 serving as a binder, and the electrode slurry layer 13 further includes a plurality of the composite conductive assistant particles 100. The weight percentage of the plurality of composite conductive assistant particles 100 in the electrode slurry layer 13 ranges from 2 wt% to 10 wt%.

[0012] The structure of the composite conductive assistant particles 100 of the present case is described below. The composite conductive assistant particles 100 comprise: A ceramic particle 15, which has high ionic conductivity for lithium ions. Therefore, when lithium ions pass through the electrode 10, the ceramic particle 15 is used to guide and disperse the lithium ions, so that uniformly distributed lithium ion channels can be formed in the electrode 10, preventing abnormal accumulation of lithium ions in the electrode slurry 12 that would cause side reactions with the electrode slurry 12. The particle size of the ceramic particle 15 is less than 100 nanometers.

[0013] The ceramic particle 15 is an oxide with a garnet or perovskite structure. Examples of the oxide with a garnet or perovskite structure include lithium lanthanum zirconium oxide (Li7La3Zr2O 12 , lithium lanthanum zirconium oxide, LLZO) or at least one of lithium lanthanum titanium oxide (lithium lanthanum titanium oxide, LLTO).

[0014] Wherein when the ceramic particle 15 is made of LLZO, the LLZO material is selected from at least one of LLZO, Ga-LLZO (Ga-doped LLZO), Cu-LLZO (Cu-doped LLZO), Ta-LLZO (Ta-doped LLZO), Sr-LLZO (Sr-doped LLZO) and Al-LLZO (Al-doped LLZO).

[0015] When the ceramic particle is made of lithium lanthanum titanium oxide, the lithium lanthanum titanium oxide is selected from Li 3x La 2 / (3-x) TiO3, where 0<x<0.167 (such as Li0.33 La 0.56 TiO3), gallium-doped lithium lanthanum titanium oxide, copper-doped lithium lanthanum titanium oxide, tantalum-doped lithium lanthanum titanium oxide, strontium-doped lithium lanthanum titanium oxide, aluminum-doped lithium lanthanum titanium oxide, or a combination of at least two of these.

[0016] A dopamine layer 35 is coated on the outer surface of the ceramic particle 15, and the dopamine layer 35 and the corresponding ceramic particle 15 form a primary and secondary composite particle 110 (e.g., Figure 1 (As shown). The dopamine layer 35 is composed of polydopamine molecules. The bonding method between the polydopamine molecules and the ceramic particles 15 is well known in the art and will not be described in detail here. For example, the ceramic particles 15 are dehydrated and polymerized via the OH- bonds in the dopamine through hydrogen bonding on their exterior.

[0017] A PVDF (polyvinylidene difluoride) layer 41 is coated on the outer surface of the secondary composite particle 110, and the PVDF layer 41 and the corresponding secondary composite particle 110 form the composite conductive particle 100 (e.g. Figure 1 (As shown). The PVDF layer 41 is composed of PVDF. The thickness of the dopamine layer 35 is between 2 nm and 15 nm; the thickness of the PVDF layer 41 is between 10 nm and 100 nm.

[0018] Traditional ceramic particles have a large number of alkaline groups (such as OH-, Li2O) on their surface. Therefore, during the manufacturing process, when multiple traditional ceramic particles are added to the positive electrode slurry, these alkaline groups on the particles react with the solvent in the slurry, making the slurry strongly alkaline. This causes degradation of both the positive electrode particles and the slurry, which in turn affects the difficulty of the manufacturing process and makes the electrochemical properties of the produced positive electrode plate less than expected. In the prior art, a dopamine layer 35 is coated on the surface of the traditional ceramic particles to protect them. However, the dopamine layer 35 cannot completely cover the outer surface of the ceramic particles 15, so a small portion of the surface of the ceramic particles 15 remains exposed.

[0019] In this invention, the dopamine layer 35 does not completely cover the outer surface of the ceramic particle 15, so a small portion of the surface of the ceramic particle 15 remains exposed. Therefore, the PVDF layer 41 partially contacts the surface of the ceramic particle 15 and partially contacts the dopamine layer 35. When multiple ceramic particles coated with the dopamine layer 35 (i.e., the secondary composite particles 110) are added to the positive electrode slurry, the exposed parts of the secondary composite particles 110 react with the solvent in the positive electrode slurry, making the positive electrode slurry strongly alkaline. Therefore, this invention further coats the outer surface of the secondary composite particles 110 with a PVDF layer 41 as a protective layer, so that the PVDF layer 41 further protects the internal secondary composite particles 110 and prevents them from reacting with the solvent in the positive electrode slurry, thus preventing the degradation of the positive electrode slurry.

[0020] In this PVDF, some of the fluorine ions (F-) react with the lithium ions (Li-) on the surface of the corresponding ceramic particles 15. - The ionic bonds formed in this PVDF 40 create lithium fluoride (LiF); while the other portion of the fluoride ions (F) in this PVDF 40... - ) will react with the nitrogen ions (N) of the polydopamine molecules on the surface of the secondary composite particle 110. - Hydrogen bonds are formed, so the PVDF 40 will form a PVDF layer 41 covering the outer surface of the secondary composite particle 110.

[0021] The advantage of this invention is that a PVDF layer is applied as a protective layer to the outer surface of the ceramic particles originally coated with the dopamine layer. This PVDF layer further protects the internal secondary composite particles, preventing them from reacting with the solvent in the cathode slurry and causing degradation of the cathode slurry. The above detailed description is a specific illustration of a feasible embodiment of this invention. However, this embodiment is not intended to limit the scope of this patent. All equivalent implementations or modifications that do not depart from the spirit of the technology in this invention should be included within the scope of this patent.

[0022] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A composite conductive particle coated with a dopamine layer and a PVDF layer, wherein the composite conductive particle is disposed within a slurry layer of an electrode; the composite conductive particle comprises: A ceramic particle with high ionic conductivity for lithium ions; therefore, when lithium ions pass through this electrode, the ceramic particle guides and disperses the lithium ions, resulting in a uniformly distributed lithium ion channel within the electrode. A dopamine layer is coated on the outer surface of the ceramic particle, and the dopamine layer and the corresponding ceramic particle form a primary and secondary composite particle; wherein the dopamine layer is composed of polydopamine molecules; A PVDF layer is coated on the outer surface of the secondary composite particle, and the PVDF layer and the corresponding secondary composite particle form the composite conductive particle; wherein the PVDF layer is composed of PVDF; The dopamine layer does not completely cover the outer surface of the ceramic particle, so a small portion of the ceramic particle's surface remains exposed; therefore, the PVDF layer partially contacts the ceramic particle's surface and partially contacts the dopamine layer. In this PVDF, some of its fluoride ions will form ionic bonds with the lithium ions on the surface of the corresponding ceramic particles to form lithium fluoride; while another part of the fluoride ions in the PVDF will form hydrogen bonds with the nitrogen ions of the polydopamine molecules on the surface of the secondary composite particles. Therefore, the PVDF will form a PVDF layer covering the outer surface of the secondary composite particles. in, The ceramic particles are oxides with garnet or perovskite structures.

2. The composite conductive particles coated with a dopamine layer and a PVDF layer as described in claim 1, characterized in that, The particle size of each of these composite guiding particles is less than 300 nanometers.

3. The composite conductive particles coated with a dopamine layer and a PVDF layer as described in claim 1, characterized in that, The composite guiding particles account for between 2 wt% and 10 wt% of the weight of the slurry layer.

4. The composite conductive particles coated with a dopamine layer and a PVDF layer as described in claim 1, characterized in that, The size of each ceramic particle is less than 100 nanometers.

5. The composite conductive particles coated with a dopamine layer and a PVDF layer as described in claim 1, characterized in that, The oxide with a garnet or perovskite structure is lithium lanthanum zirconium oxide.

6. The composite conductive particles coated with a dopamine layer and a PVDF layer according to claim 5, characterized in that, The lithium lanthanum zirconium oxide is selected from Li7La3Zr2O 12 One or a combination of at least two of the following: gallium-doped lithium lanthanum zirconium oxide, copper-doped lithium lanthanum zirconium oxide, tantalum-doped lithium lanthanum zirconium oxide, strontium-doped lithium lanthanum zirconium oxide, and aluminum-doped lithium lanthanum zirconium oxide.

7. The composite conductive particles coated with a dopamine layer and a PVDF layer as described in claim 1, characterized in that, in, The oxide with a garnet or perovskite structure is lithium lanthanum titanium oxide.

8. The composite conductive particles coated with a dopamine layer and a PVDF layer as described in claim 1, characterized in that, The lithium lanthanum titanium oxide is selected from Li 3x La 2 / (3-x) TiO₃, where 0<x<0.167, one or a combination of at least two of gallium-doped lithium lanthanum titanium oxide, copper-doped lithium lanthanum titanium oxide, tantalum-doped lithium lanthanum titanium oxide, strontium-doped lithium lanthanum titanium oxide, and aluminum-doped lithium lanthanum titanium oxide.

9. The composite conductive particles coated with a dopamine layer and a PVDF layer as described in claim 1, characterized in that, The thickness of the dopamine layer is between 2 nanometers and 15 nanometers.

10. The composite conductive particles coated with a dopamine layer and a PVDF layer as described in claim 1, characterized in that, The thickness of the PVDF layer is between 10 nanometers and 100 nanometers.

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