Negative plate containing composite ceramic particles coated with a carbon layer

Abstract

A negative electrode plate is provided that includes composite ceramic particles coated with a carbon layer. [Solution] The negative electrode plate 41 including composite ceramic particles 30 coated with a carbon layer according to the present invention has a typical semi-solid battery structure, including a positive electrode 10, a negative electrode 40, and a dielectric thin film layer 49 applied between the positive and negative electrodes. The negative electrode includes a negative electrode plate having a negative electrode substrate 42 and a negative electrode slurry layer 43 coated on the negative electrode substrate, the negative electrode slurry layer being composed of a negative electrode slurry 44. The negative electrode slurry includes a plurality of negative electrode active particles 45 for storing or releasing lithium ions, an additive 47 including an adhesive and a dispersant, a plurality of conductive agents 60 for increasing the overall conductivity of the negative electrode slurry, and a plurality of the composite ceramic particles for guiding lithium ions to disperse lithium ion channels. Each of the composite ceramic particles includes ceramic particles and a carbon layer covering the outer surface of the ceramic particle.

Description

[Technical Field]

[0001] The present invention relates to a negative electrode plate for a solid or semi-solid battery, and more particularly to a negative electrode plate with ceramic composite particles having a carbon layer. [Background technology]

[0002] A battery is primarily formed by placing electrodes (positive and negative electrodes) in an electrolyte. In conventional technology, ceramic particles are added to the electrodes to increase ionic conductivity. Because the ceramic particles have high ionic conductivity for lithium ions, the dispersed ceramic particles act as guides to disperse lithium ion channels as the lithium ions pass through the electrode. This allows the lithium ions to exhibit a uniform channel distribution within the electrode.

[0003] The ceramic particles used in conventional negative electrodes are LATP. Because LATP is hydrophobic, it is not necessary to coat it with a protective layer. However, the ionic conductivity of LATP is low, and the Ti inside LATP 4+ However, during the charging and discharging process with respect to the negative electrode at a low potential, Ti 3+ It is easy to be reduced to the original state and lose its original properties. Summary of the Invention [Problem to be solved by the invention]

[0004] However, when LATP is replaced with other materials such as LLZO, which have high ionic conductivity, these materials, such as LLZO, which have high ionic conductivity, are hydrophilic and therefore decompose when they come into contact with the solvent (water) in the negative electrode slurry, resulting in a decrease in the electronic conductivity of the negative electrode slurry.

[0005] The inventors believed that the above drawbacks could be overcome, and after extensive research, they came up with a negative electrode plate containing composite ceramic particles coated with a carbon layer, which effectively overcomes the above problems through a rational design. In other words, it can protect the ceramic particles, prevent them from interacting with the solvent in the negative electrode slurry, and improve the electron conduction ability of the negative electrode slurry, thereby resolving the above-mentioned drawbacks of the prior art.

[0006] The present invention has been made in view of the above circumstances, and aims to solve the above problems by providing a negative electrode plate including composite ceramic particles coated with a carbon layer. [Means for solving the problem]

[0007] To achieve the above objective, a negative electrode plate including composite ceramic particles coated with a carbon layer according to one embodiment of the present invention has the ceramic particles coated with the carbon layer to protect the ceramic particles inside, thereby preventing the ceramic particles from undergoing side reactions with additives in the negative electrode slurry. Furthermore, by disposing a plurality of such composite ceramic particles in the negative electrode slurry, the ceramic particles according to the present invention can be made of not only conventional LATP but also LLZO, etc., thereby further diversifying the use of ceramic particles and improving the overall conductivity of the negative electrode.

[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 shows an example of a negative electrode plate including composite ceramic particles coated with a carbon layer according to the present invention. [Figure 2] 1 is a cross-sectional view showing the structure of a negative electrode plate including composite ceramic particles coated with a carbon layer in accordance with an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described below with reference to the accompanying drawings, in which: FIG. 1 is a block diagram of a conventional optical fiber cable; FIG. 2 is a block diagram of a conventional optical fiber cable;

[0011] Hereinafter, an embodiment of a negative electrode plate 11 including composite ceramic particles coated with a carbon layer according to the present invention will be described in detail with reference to FIGS.

[0012] A typical semi-solid battery structure includes a positive electrode 10, a negative electrode 40, and a dielectric thin film layer 49 applied between the positive electrode 10 and the negative electrode 40.

[0013] As shown in FIG. 1, the negative electrode 40 includes a negative electrode plate 41 . The negative electrode plate 41 includes a negative electrode substrate 42 that is a substrate on which a material for the negative electrode 40 is placed, and a negative electrode slurry layer 43 that is applied to the negative electrode substrate 42 and is composed of a negative electrode slurry 44, The negative electrode slurry 44 is a plurality of negative electrode active particles 45 for storing or releasing lithium ions, the negative electrode active particles 45 being at least one selected from a carbon material (the carbon material includes graphite, hard carbon, soft carbon, etc.), a silicon-carbon composite material (Si-C), a silicon-oxygen-carbon composite material (SiOx-C), etc., and the ratio of the plurality of negative electrode active particles 45 to the entire negative electrode slurry layer 43 is in the range of 85 wt% to 97 wt%; an additive 47 including an adhesive and a dispersant, the adhesive being a polymer material such as SBR (Styrene-Butadiene Rubber), the dispersant being selected from inorganic salts, organic molecules, and polymer materials, for example, at least one selected from CMC (Carboxymethyl Cellulose), benzenesulfonate salts, ammonium bromide salts, Triton X-100, etc., the ratio of the additive 47 to the entire negative electrode slurry layer 43 being in the range of 2 wt% to 6 wt%, and the weight ratio of the adhesive to the dispersant being in the range of 3:1 to 1:3; a plurality of conductive agents 60 formed of at least one material selected from the group consisting of carbon nanotubes, graphene, and amorphous carbon, the ratio of the plurality of conductive agents 60 to the entire negative electrode slurry layer 43 being in the range of 0.5 wt % to 7 wt %, the conductive agents 60 being used to increase the conductivity of the entire negative electrode slurry 44, and the plurality of conductive agents 60 in the negative electrode 40 being capable of suppressing expansion of the plurality of negative electrode active particles 45 in addition to increasing the conductivity of the negative electrode slurry 44; The plurality of composite ceramic particles 30 are used to guide lithium ions so as to disperse lithium ion channels and prevent lithium ions from abnormally accumulating in the negative electrode slurry 44 and causing a side reaction with the negative electrode slurry 44. As shown in FIG. 2 , the composite ceramic particles 30 include ceramic particles 301 and carbon layers 302 that cover the outer surfaces of the ceramic particles 301, and the ratio of the plurality of composite ceramic particles 30 to the entire negative electrode slurry layer 43 is in the range of 0.1 wt % to 2 wt %, and the particle size of each of the composite ceramic particles 30 is less than 200 nm.

[0014] The negative electrode active particles 45 are distributed so as to be dispersed in the negative electrode slurry layer 43, and the conductive agent 60 and the composite ceramic particles 30 are dispersed among the negative electrode active particles 45. The adhesive is used to adhere the above-mentioned materials in the negative electrode slurry 44, and the dispersant is used to appropriately disperse the above-mentioned materials in the negative electrode slurry 44 so that they do not settle at the bottom of the negative electrode slurry 44 due to gravity.

[0015] The ceramic particles 301 used in conventional negative electrodes are LATP. Because LATP is hydrophobic, there is no need to coat it with a protective layer (e.g., the carbon layer 302 of the present invention). However, the ionic conductivity of LATP is low, and the Ti inside LATP is 4+ However, during the charge and discharge process for the negative electrode at low potential, Ti 3+ However, LLZO powder is easily reduced to 0.25% by weight, losing its inherent properties. Therefore, the present invention provides an alternative solution. Specifically, LATP is replaced by solid electrolyte particles for use in the negative electrode using a material such as LLZO, which has high ionic conductivity. However, two problems remain: LLZO powder decomposes when it comes into contact with water, which is commonly used as a negative electrode slurry solvent, and LLZO has low electronic conductivity. Therefore, coating the outer surfaces of materials such as LLZO with the carbon layer 302 can solve these problems. Coating the outer surfaces of the ceramic particles 301 with the carbon layer 302 reduces contact between the water in the negative electrode slurry solvent and the surfaces of the ceramic particles 301, thereby reducing decomposition of the ceramic particles 301 when they come into contact with water. The carbon layer 302 also enhances the electronic conductivity within the negative electrode plate 41, improving electronic conductivity and overcoming known problems.

[0016] The ceramic particles 301 have a lithium ion conducting ability (ionic conductivity is 10 -5 cm 2 / s) or oxides with a garnet or perovskite structure.

[0017] The oxide or phosphate having lithium ion conductivity is, for example, lithium aluminum titanium phosphate (LATP), lithium aluminum germanium phosphate (LAGP), or a phosphate having lithium ion conductivity, such as lithium phosphate (Li3PO4), which has a NASICON (sodium (Na) superionic conductor) structure. The oxide having a garnet or perovskite structure is, for example, lithium lanthanum zirconium oxide (Li7La3Zr2O 12 The ceramic particles 301 may be a combination of the above components in any ratio.

[0018] When the ceramic particles 301 are made of LLZO, the LLZO material is formed by selecting at least one 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).

[0019] When the ceramic particles 301 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 My N z (PO4)3. When the ceramic particles 301 are made of LATP, the LATP is selected from Li 1+x Al x Ti 2-x (PO4)3 or Li 1+x+y Al x Ti 2-x-y-z M y N z (PO4)3, where 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) and other trivalent cations. 4+ (zirconium ion), Si 4+ (silicon ion), Sn 4+ (tin ion) and other tetravalent cations.

[0020] The carbon layer 302 covers the outer surface of the ceramic particle 301. The radial thickness of the carbon layer 302 is less than 10 nm. The carbon layer 302 itself has suitable electrical conductivity and can suppress excessive volume expansion when the ceramic particle 301 is filled with lithium ions. Therefore, by covering the outer surface of the ceramic particle 301 with the carbon layer 302, it is possible to achieve a protective effect that prevents damage to the entire composite ceramic particle 30.

[0021] As shown in FIG. 2, the carbon layer 302 includes amorphous carbon 52, and the amorphous carbon 52 is formed of at least one of the following: (i) Hard carbon or soft carbon formed by sintering and debinding organic resins, or hard carbon or soft carbon formed by sintering and debinding organic carbohydrates. (ii) Amorphous carbon formed from an organic compound in a reducing atmosphere. The organic compound is selected from carbohydrates (e.g., monosaccharides, disaccharides, oligosaccharides, polysaccharides), water-soluble fibers, amino acid polymers, etc. Preferably, the organic compound is a carbon-containing compound containing at least one element selected from nitrogen, fluorine, phosphorus, and sulfur. The carbon is doped with these elements (i.e., nitrogen, fluorine, phosphorus, or sulfur) through a reduction reaction, thereby increasing the electronic conductivity of the composite ceramic particles 30. (iii) Amorphous carbon formed by dehydration of carbohydrates. (iv) Amorphous carbon containing multiple carbon skeletons and partial functional groups, formed by dehydration of water-soluble fibers. (v) Amorphous carbon formed by dehydration of amino acid polymers, which is composed of multiple carbon skeletons with straight chains or side chains containing doping elements.

[0022] A plurality of graphene sheets 54 are mixed in the carbon layer 302. The graphene sheets 54 are multi-layer graphene having 2 to 10 layers, and the sheet diameter of the graphene sheets 54 is less than 500 nm. Each of the graphene sheets 54 has a sheet-like structure and covers the corresponding ceramic particle 301, forming a layer-like covering form across the entire surface.

[0023] A plurality of carbon nanotubes 56 are mixed in the carbon layer 302. The size of the carbon nanotubes 56 is less than 1 μm. When the graphene sheet 54 coats the ceramic particle 301, gaps are formed between them. By using the plurality of carbon nanotubes 56 as bridges between the graphene sheet 54 and the ceramic particle 301 or between different graphene sheets 54, the electron guiding efficiency of each composite ceramic particle 30 is further improved. The carbon layer 302, in which the plurality of graphene sheets 54 and the plurality of carbon nanotubes 56 are mixed, coats the ceramic particle 301, thereby forming the corresponding composite ceramic particle 30.

[0024] In one composite ceramic particle 30, the weight ratio of the ceramic particles 301 to the total weight of the carbon layers 302 is 99.5:0.5, and the weight ratio of the graphene sheets 54 to the total weight of the carbon nanotubes 56 is 4:1.

[0025] As shown in Figure 2, the present invention further includes a plurality of lithium fluoride (LiF) particles 55 distributed within the carbon layer 302. The carbon layer 302 has a certain thickness, which makes it difficult for lithium ions to pass through the composite ceramic particle 30. The plurality of lithium fluoride particles 55 distributed within the carbon layer 302 serve as springboards for lithium ion channels, allowing the lithium ions to pass through the composite ceramic particle 30 via the plurality of lithium fluoride particles 55, helping to guide the lithium ions. The plurality of lithium fluoride particles are distributed in an island-like pattern.

[0026] The size of the lithium fluoride particles 55 is less than 5 nm. In one composite ceramic particle 30 in which a plurality of the lithium fluoride particles 55 are mixed, the weight ratio of the ceramic particle 301 to the total weight of the plurality of the lithium fluoride particles 55 is in the range of 99.9 to 99.95:0.1 to 0.05.

[0027] 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 devised in different embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0028] 10 positive electrode 30 Composite ceramic particles 40 negative electrode 41 Negative electrode plate 42 Negative substrate 43 Negative electrode slurry layer 44 Anode slurry 45 Negative electrode active particles 47 Additives 49 Dielectric Thin Film Layer 52 Amorphous Carbon 54 Graphene Sheet 55 Lithium fluoride particles 56 Carbon nanotubes 60 Conductive Agent 301 Ceramic particles 302 carbon layer

Claims

1. A negative electrode plate including composite ceramic particles coated with a carbon layer for use in a solid or semi-solid battery structure including a positive electrode, a negative electrode, and a dielectric thin film layer applied between the positive electrode and the negative electrode, the negative electrode includes the negative electrode plate, The negative electrode plate is a negative electrode substrate that is a substrate for placing the negative electrode material; a negative electrode slurry layer applied to the negative electrode substrate, the negative electrode slurry layer being made of a negative electrode slurry; The negative electrode slurry is a plurality of negative electrode active particles for storing or releasing lithium ions; an additive including an adhesive and a dispersant, wherein the adhesive is used to adhere each material in the negative electrode slurry, and the dispersant is used to appropriately disperse each material in the negative electrode slurry; a plurality of conductive agents for increasing the conductivity of the entire negative electrode slurry; a plurality of the composite ceramic particles used to guide lithium ions so as to disperse lithium ion channels and prevent lithium ions from abnormally accumulating in a negative electrode slurry and causing a side reaction with the negative electrode slurry, each of the composite ceramic particles including a ceramic particle and a carbon layer covering an outer surface of the ceramic particle, the carbon layer being used to isolate oxygen ions on the surface of the ceramic particle from a solvent in the negative electrode slurry so as not to interact with each other, the carbon layer itself having suitable electrical conductivity and capable of suppressing excessive expansion of volume when lithium ions are filled into the ceramic particles, a negative electrode plate including composite ceramic particles coated with a carbon layer, characterized in that the negative electrode active particles are distributed so as to be dispersed in the negative electrode slurry layer, the conductive agent and the composite ceramic particles are dispersed among the negative electrode active particles, the particle size of the composite ceramic particles is less than 200 nm, and the radial thickness of the carbon layer is less than 10 nm.

2. The carbon layer comprises amorphous carbon, the amorphous carbon comprising: hard or soft carbon formed by sintering and degreasing organic resins or organic carbohydrates; Amorphous carbon formed from organic compounds in a reducing atmosphere; amorphous carbon formed by dehydration of carbohydrates; Amorphous carbon containing multiple carbon skeletons and partial functional groups, which is formed by dehydrating water-soluble fibers; 2. A negative electrode plate comprising composite ceramic particles coated with a carbon layer according to claim 1, characterized in that the composite ceramic particles are formed from at least one of: amorphous carbon formed by dehydrating an amino acid polymer and having multiple linear or side chain carbon skeletons containing a doping element;

3. 3. The negative electrode plate comprising composite ceramic particles coated with a carbon layer according to claim 2, wherein the organic compound is a carbohydrate, and the carbohydrate is at least one selected from the group consisting of monosaccharides, disaccharides, oligosaccharides, polysaccharides, water-soluble fibers, and amino acid polymers.

4. 3. The negative electrode plate comprising composite ceramic particles coated with a carbon layer according to claim 2, wherein the organic compound is a carbon-containing compound containing at least one element selected from the group consisting of nitrogen, fluorine, phosphorus, and sulfur.

5. 2. The negative electrode plate according to claim 1, wherein the weight ratio of the ceramic particles to the total weight of the carbon layer in one composite ceramic particle is 99.5:0.

5.

6. 2. The negative electrode plate according to claim 1, wherein a ratio of the plurality of negative electrode active particles to the entire negative electrode slurry layer is between 85 wt % and 97 wt %, a ratio of the additive to the entire negative electrode slurry layer is between 2 wt % and 6 wt %, a weight ratio of the adhesive to the dispersant is between 3:1 and 1:3, a ratio of the conductive agent to the entire negative electrode slurry layer is between 0.5 wt % and 7 wt %, and a ratio of the plurality of composite ceramic particles to the entire negative electrode slurry layer is between 0.1 wt % and 2 wt %.

7. The ceramic particles have a lithium ion conducting ability (ionic conductivity is 10 －５ cm ２ 2. The negative electrode plate comprising composite ceramic particles coated with a carbon layer according to claim 1, characterized in that the composite ceramic particles are formed of at least one of ceramic oxides or phosphates having a porosity of 1 / s or more, or oxides having a garnet or perovskite structure.

8. The oxide having a garnet or perovskite structure is lithium lanthanum zirconium oxide (Li ７ La ３ Zr ２ O １２ 8. The negative electrode plate comprising composite ceramic particles coated with a carbon layer according to claim 7, wherein at least one of the composite ceramic particles is selected from the group consisting of lithium lanthanum titanium oxide (LLTO) and lithium lanthanum titanium oxide (LLTO).

9. 2. The negative electrode plate according to claim 1, wherein the ceramic particles are LLZO.

10. 2. The negative electrode plate according to claim 1, wherein the ceramic particles are formed of an LLZO material, and the LLZO material is at least one selected 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).

11. 2. The negative electrode plate comprising composite ceramic particles coated with a carbon layer according to claim 1, further comprising a plurality of graphene sheets mixed in the carbon layer, the graphene sheets being multi-layer graphene having 2 to 10 layers, and the sheet diameter of the graphene sheets being less than 500 nm.

12. 2. The negative electrode plate comprising composite ceramic particles coated with a carbon layer according to claim 1, further comprising a plurality of carbon nanotubes mixed within the carbon layer.

13. 2. The negative electrode plate according to claim 1, further comprising a plurality of lithium fluoride particles distributed in the carbon layer, the plurality of lithium fluoride particles serving as springboards for lithium ion channels, and the lithium ions passing through the plurality of lithium fluoride particles in the composite ceramic particles help guide the lithium ions, and the plurality of lithium fluoride particles are distributed in an island-like manner.

14. 2. The negative electrode plate according to claim 1, wherein the negative electrode active particles are at least one selected from the group consisting of graphite, hard carbon, soft carbon, a silicon-carbon composite material, and a silicon-oxygen-carbon composite material; the adhesive is selected from SBR; the dispersant is at least one selected from the group consisting of inorganic salts, organic molecules, and polymer materials; and the conductive agent is at least one selected from the group consisting of carbon nanotubes, graphene, and amorphous carbon.

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