Phosphate-based composite conductive particles coated with dopamine and PVDF layers

Abstract

A phosphate-based composite conductive particle layer structure is provided, which is coated with a dopamine layer and a PVDF layer. [Solution] The phosphate-based composite conductive particle 100 of the present invention, which is coated with a dopamine layer 35 and a PVDF (polyvinylidene difluoride) layer 41, comprises ceramic particles 15 for guiding and dispersing lithium ions, a dopamine layer coating the outer surface of the ceramic particle, where the dopamine layer and corresponding ceramic particles form secondary composite particles 110, the dopamine layer being composed of copolymerized dopamine molecules, and a PVDF layer coating the outer surface of the secondary composite particle, where the PVDF layer and corresponding secondary composite particles form composite conductive particles, the PVDF layer being composed of PVDF.

Description

[Technical Field]

[0001] The present invention relates to positive electrode particles, and more particularly to phosphate-based composite conductive particles having a dopamine layer (a layer containing polydopamine) and a PVDF layer. [Background technology]

[0002] Batteries are typically constructed by placing a positive electrode and a negative electrode in an electrolyte solution, and conventional technologies have increased ionic conductivity by adding ceramic particles to the negative electrode. Because ceramic particles have high ionic conductivity for lithium ions, lithium ions are guided by the dispersed ceramic particles as they pass through the negative electrode, creating lithium ion channels, which distribute the lithium ions uniformly within the positive electrode. Summary of the Invention [Problem to be solved by the invention]

[0003] However, the surface of conventional ceramic particles contains a large amount of alkaline functional groups (e.g., OH - , Li2O), when multiple conventional ceramic particles are added to a positive electrode slurry during the manufacturing process, the alkaline functional groups of the multiple ceramic particles interact with the solvent in the positive electrode slurry, resulting in a strongly alkaline positive electrode slurry. This causes deterioration of the positive electrode particles and the positive electrode slurry, impacts the manufacturing process, and makes it difficult for the electrochemical properties of the manufactured positive electrode plate to be as expected. Conventional techniques have been used to coat the outer surfaces of the ceramic particles with a dopamine layer to protect them. However, the dopamine layer does not completely cover the outer surfaces of the ceramic particles, leaving some of the ceramic particle surfaces exposed. Furthermore, in the conventional techniques, after multiple ceramic particles coated with the dopamine layer are added to a positive electrode slurry, the exposed portions of the secondary composite particles interact with the solvent in the positive electrode slurry, resulting in a strongly alkaline positive electrode slurry.

[0004] After extensive research, the inventors discovered that the above objective could be achieved by adopting a novel phosphate-based composite conductive particle having a dopamine layer and a PVDF layer, and thus completed the present invention.

[0005] The present invention has been made in view of these circumstances, and its object is to provide phosphate-based composite conductive particles having a dopamine layer and a PVDF layer. [Means for solving the problem]

[0006] In order to achieve the above object, in one embodiment of the present invention, phosphoric acid-based composite conductive particles having a dopamine layer and a PVDF layer are disposed in an electrode slurry layer, and the composite conductive particles are: Ceramic particles having high ionic conductivity to lithium ions, which serve to guide and disperse the lithium ions as they pass through the electrode, forming lithium ion channels that are uniformly distributed within the electrode; a dopamine layer covering the outer surface of the ceramic particle, the dopamine layer and the corresponding ceramic particle forming a secondary composite particle, the dopamine layer being composed of copolymerized dopamine molecules; a PVDF layer covering the outer surface of the secondary composite particle, the PVDF layer and the corresponding secondary composite particle forming the composite conductive particle, the PVDF layer being made of a PVDF material; the dopamine layer incompletely covers the outer surfaces of the ceramic particles, leaving the surfaces of some of the ceramic particles exposed, so that the PVDF layer is in partial contact with the surfaces of the ceramic particles and the dopamine layer; In the PVDF material, some of the fluorine ions are bonded to the lithium ions on the surface of the corresponding ceramic particles through ionic bonds to form lithium fluoride, and other parts of the fluorine ions in the PVDF material are bonded to the nitrogen ions of the copolymerized dopamine molecules on the surface of the secondary composite particles through hydrogen bonds, and the PVDF material forms a PVDF layer covering the outer surface of the secondary composite particles. [Effects of the Invention]

[0007] In the present invention, the outer surfaces of the ceramic particles, which are originally coated with the dopamine layer, are further coated with the PVDF layer as a protective layer, so that the PVDF layer further protects the internal secondary composite particles from reacting with the solvent in the positive electrode slurry and deteriorating the positive electrode slurry.

[0008] At least the following points will become clear from the description and drawings to be described later. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing the structure of a phosphate-based composite conductive particle having a dopamine layer and a PVDF layer according to the present invention. FIG. [Figure 2] 1 shows an embodiment of a phosphate-based composite conductive particle having a dopamine layer and a PVDF layer according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] The following describes in detail the preferred embodiments of the present invention, but the present invention is not limited to these, and various modifications are possible within the scope of the description. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0011] Fig. 1 is a cross-sectional view showing the structure of a phosphate-based composite conductive particle having a dopamine layer and a PVDF layer according to the present invention, and Fig. 2 shows one embodiment of a phosphate-based composite conductive particle having a dopamine layer and a PVDF layer according to the present invention.

[0012] The phosphate-based composite conductive particles having a dopamine layer and a PVDF layer according to the present invention are primarily used in electrodes 10 for solid-state or semi-solid-state batteries. In application, a plurality of the composite conductive particles 100 are disposed within the electrode 10, which is particularly a positive electrode for the solid-state or semi-solid-state battery. The particle size of the composite conductive particles 100 is less than 300 nm. The electrode 10 includes an electrode substrate 11 on which the material of the electrode 10 is mounted. An electrode slurry layer 13 is applied to the electrode substrate 11 and contains an electrode slurry 12 as a binder. The electrode slurry layer 13 further contains a plurality of the composite conductive particles 100. The weight percentage of the composite conductive particles 100 in the electrode slurry layer 13 ranges from 2 wt% to 10 wt%.

[0013] The following describes the configuration of the composite conductive particle 100. The composite conductive particle 100 mainly comprises the following components.

[0014] <Ceramic particles 15> Due to their high ionic conductivity to lithium ions, the ceramic particles 15 are used to guide and disperse the lithium ions as they pass through the electrode 10, enabling the formation of uniformly distributed lithium ion channels within the electrode 10, and preventing the lithium ions from abnormally accumulating in the electrode slurry 12 and causing side reactions with the electrode slurry 12. The particle size of the ceramic particles 15 is less than 100 nm.

[0015] The ceramic particles 15 have a lithium ion conducting ability (ionic conductivity of 10 -5 cm 2The ceramic oxide having lithium ion conductivity is at least one of a ceramic oxide having a diffusion coefficient of more than 1 / s, an oxide having a garnet structure, and an oxide having a perovskite structure. The ceramic oxide having lithium ion conductivity is, for example, lithium aluminum germanium phosphate (LAGP) having a NASICON (sodium (Na) super ionic conductor) structure, and the oxide having a garnet structure is, for example, lithium lanthanum zirconium oxide (Li7La3Zr2O 12 The oxide having the perovskite structure is, for example, lithium lanthanum titanium oxide (LLTO).

[0016] When the ceramic particles 15 are made of LLZO, the LLZO material is formed by selecting at least one from the group consisting of LLZO, Ga-LLZO (Ga-doped LLZO, gallium-doped lithium-lanthanum-zirconium oxide), Cu-LLZO (Cu-doped LLZO, copper-doped lithium-lanthanum-zirconium oxide), Ta-LLZO (Ta-doped LLZO, tantalum-doped lithium-lanthanum-zirconium oxide), Sr-LLZO (Sr-doped LLZO, strontium-doped lithium-lanthanum-zirconium oxide), and Al-LLZO (Al-doped LLZO, aluminum-doped lithium-lanthanum-zirconium oxide).

[0017] When the ceramic particles 15 are made of LAGP, the LAGP is Li 1+x Al x Ge 2-x (PO4)3, or Li 1+x+y Al x Ge 2-x-y-z M y N z(PO4)3 is selected, x is in the range of 0.1 to 0.8, y is in the range of 0 to 0.2, and z is in the range of 0 to 0.2. M is Sc 3+ (scandium ion), Y 3+ (yttrium ion), Ga 3+ (gallium ion), In 3+ (indium ion), La 3+ (lanthanum ion), etc., which are trivalent cations. N is Zr 4+ (zirconium ion), Si 4+ (silicon ion), Sn 4+ (tin ion), etc., which are tetravalent cations.

[0018] <Dopamine layer 35> Coats the outer surface of the ceramic particles 15, and the secondary composite particles 110 are formed by the dopamine layer 35 and the corresponding ceramic particles 15 (see Figure 1). The dopamine layer 35 is a layer containing polydopamine and is composed of copolymerized dopamine molecules. The bonding method between the copolymerized dopamine molecules and the ceramic particles 15 is well-known in the prior art, so the description is not repeated here. For example, the ceramic particles 15 are bonded to the outside by OH - bonds and OH - bonds in dopamine to undergo dehydration copolymerization.

[0019] <PVDF (polyvinylidene difluoride) layer 41> Coats the outer surface of the secondary composite particles 110, and the composite conductive particles 100 are formed by the PVDF layer 41 and the corresponding secondary composite particles 110 (see Figure 1). The PVDF layer 41 is composed of PVDF material. The thickness of the dopamine layer 35 is in the range of 2 nm to 15 nm. The thickness of the PVDF layer 41 is in the range of 10 nm to 100 nm. <00​​​, Li2O), when conventional ceramic particles are added to a positive electrode slurry during the manufacturing process, the alkaline functional groups of the conventional ceramic particles interact with the solvent in the positive electrode slurry, resulting in a strongly alkaline positive electrode slurry. This deteriorates the positive electrode particles and the positive electrode slurry, increases the manufacturing difficulty, and can lead to unexpected electrochemical properties of the resulting positive electrode plate. Conventional techniques already exist for coating the outer surfaces of conventional ceramic particles with a dopamine layer 35 to protect the ceramic particles. However, the dopamine layer 35 does not completely cover the outer surfaces of the ceramic particles 15, leaving some of the surfaces of the ceramic particles 15 exposed.

[0021] In the technology of the present invention, the dopamine layer 35 incompletely covers the outer surfaces of the ceramic particles 15, leaving some of the surfaces of the ceramic particles 15 exposed. Therefore, the PVDF layer 41 partially contacts the surfaces of the ceramic particles 15 and the dopamine layer 35. When a plurality of ceramic particles (i.e., the secondary composite particles 110) covered with the dopamine layer 35 are added to a positive electrode slurry, the exposed portions of the secondary composite particles 110 interact with the solvent in the positive electrode slurry, causing the positive electrode slurry to exhibit a strong alkaline property. In this way, the outer surfaces of the secondary composite particles 110 according to the present invention are further covered by the PVDF layer 41 as a protective layer, and the PVDF layer 41 further protects the internal secondary composite particles 110 from reacting with the solvent in the positive electrode slurry and deteriorating the positive electrode slurry.

[0022] The partial fluorine ions (F - ) on the surface of the corresponding ceramic particle 15. + ) by ionic bonding to form lithium fluoride (LiF). The other partial fluorine ions (F - ) of the copolymerized dopamine molecules on the surface of the secondary composite particle 110. 3-) by hydrogen bonding, and the PVDF material forms a PVDF layer 41 that covers the outer surface of the secondary composite particle 110.

[0023] The advantage of the present invention is that the outer surfaces of the ceramic particles, which are originally coated with the dopamine layer, are further coated with the PVDF layer as a protective layer, which further protects the internal secondary composite particles from reacting with the solvent in the cathode slurry and causing deterioration of the cathode slurry.

[0024] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0025] 10 electrodes 11 Electrode substrate 12 Electrode slurry 13 Electrode slurry layer 15 Ceramic particles 35 Dopamine layer (layer containing polydopamine) 41 PVDF layer 100 Composite conductive particles 110 Secondary composite particles

Claims

1. Phosphate-based composite conductive particles having a dopamine layer and a PVDF layer, the composite conductive particles being disposed in an electrode slurry layer; and Ceramic particles having high ionic conductivity to lithium ions, which serve to guide and disperse the lithium ions as they pass through the electrode, forming lithium ion channels that are uniformly distributed within the electrode; a dopamine layer covering the outer surface of the ceramic particle, the dopamine layer and the corresponding ceramic particle forming a secondary composite particle, the dopamine layer being composed of copolymerized dopamine molecules; A phosphate-based composite conductive particle having a dopamine layer and a PVDF layer, characterized in that it comprises a PVDF layer covering the outer surface of the secondary composite particle, the PVDF layer and the corresponding secondary composite particle forming the composite conductive particle, the PVDF layer being made of a PVDF material.

2. The phosphate-based composite conductive particles having a dopamine layer and a PVDF layer according to claim 1 , wherein the particle size of each of the composite conductive particles is less than 300 nm.

3. The phosphate-based composite conductive particle having a dopamine layer and a PVDF layer according to claim 1, characterized in that the weight percentage of the composite conductive particles in the electrode slurry layer is in the range of 2 wt% to 10 wt%.

4. The phosphate-based composite conductive particle having a dopamine layer and a PVDF layer according to claim 1 , wherein the particle size of each of the ceramic particles is less than 100 nm.

5. The ceramic particles have an ionic conductivity of 10 －５ cm ２ The phosphate-based composite conductive particles having a dopamine layer and a PVDF layer according to claim 1, characterized in that the conductive particles are at least one of ceramic oxides having a porcelain garnet structure or oxides having a perovskite structure, each of which has a porosity of 0.05 to 0.15 / s or more.

6. The phosphate-based composite conductive particles having a dopamine layer and a PVDF layer according to claim 5, characterized in that the ceramic oxide is selected from germanium aluminum lithium phosphates having a NASICON structure.

7. When the ceramic particles are composed of LAGP, the LAGP is Li １＋ｘ Al ｘ Ge ２－ｘ (P.O. ４ ) ３ , or Li １＋ｘ＋ｙ Al ｘ Ge ２－ｘ－ｙ－ｚ M ｙ N ｚ (P.O. ４ ) ３ wherein x is in the range of 0.1 to 0.8, y is in the range of 0 to 0.2, z is in the range of 0 to 0.2, M is a trivalent cation, and N is a tetravalent cation.

8. The trivalent cation is Sc ３＋ (Scandium ion), Y ３＋ (yttrium ion), Ga ３＋ (Gallium ion), In ３＋ (indium ion), La ３＋ (lanthanum ion), and the tetravalent cation is selected from Zr ４＋ (zirconium ion), Si ４＋ (silicon ion), Sn ４＋ 8. The phosphate-based composite conductive particle having a dopamine layer and a PVDF layer according to claim 7, characterized in that the phosphate-based composite conductive particle has a dopamine layer and a PVDF layer, and the phosphate-based composite conductive particle has a tin ion.

9. The phosphate-based composite conductive particle having a dopamine layer and a PVDF layer according to claim 1, wherein the thickness of the dopamine layer is in the range of 2 nm to 15 nm.

10. The phosphate-based composite conductive particle having a dopamine layer and a PVDF layer according to claim 1, wherein the thickness of the PVDF layer is in the range of 10 nm to 100 nm.

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