Conductive particles with phosphoric acids in a positive or negative electrode

Abstract

A conductive particle containing phosphoric acids for a positive or negative electrode; the positive or negative electrode being used in a solid-state or semi-solid-state battery; the conductive particle comprising: a ceramic particle which serves to conduct lithium ions through the positive or negative electrode and to cause the positive or negative electrode to have evenly distributed lithium ion channels; an amorphous carbon layer on the outer surface of the ceramic particle; the amorphous carbon layer has a specific conductivity to prevent excessive volume expansion of the ceramic particle when it is filled with lithium ions; a plurality of graphene layers incorporated into the amorphous carbon layer; each of the graphene layers has a layered structure; the graphene layers form a multilayer structure enclosing the outer surface of the ceramic particle; and a plurality of first carbon nanotubes (CNTs) incorporated into the amorphous carbon layer; The first carbon nanotube is distributed in the spaces between the graphene layers and the ceramic particle, as well as in the spaces between different graphene layers, and serves as a bridge between the graphene layers and the ceramic particle.

Description

FIELD OF THE INVENTIONThe invention relates to battery electrode material and more particularly to a conductive particle having phosphoric acids in a positive or negative electrode.BACKGROUND OF THE INVENTIONA typical battery consists mainly of positive and negative electrodes in an electrolyte. In the prior art, LLZO material is added to an electrode to increase its ionic conductivity. Since LLZO material has high lithium ion conductivity, the lithium ion channels in the electrode can be distributed by guiding the dispersed LLZO particles as the lithium ions pass through within the electrode. This results in uniformly distributed lithium ion channels in the electrode. This prevents side reactions with the electrode mass which are formed by an abnormal deposition of lithium ions in this electrode mass.Since moisture is generated during the electrode manufacturing process, the LLZO particles are hydrophilic and can easily become wet, thereby forming alkali. Therefore, the LLZO particles must be coated with a protective layer to prevent moistening during the manufacturing process. In the prior art, the LLZO particles are coated with dopamine. However, dopamine has poor electrical conductivity and reduces the electrical conductivity of the electrode plates. Based on the applicant's many years of experience with battery materials, the invention aims at a novel design: the outer surface of the LLZO material is coated with a carbon layer to render it hydrophobic and thus prevent the penetration of moisture. The carbon layer may increase the overall conductivity of the electrode particles. In addition, lithium fluoride particles are added to the carbon layer to increase the ionic conductivity. Carbon nanotubes improve the conductivity of the entire electrode, thereby reducing the volume expansion of the electrode particles and increasing the performance of the electrode.SUMMARY OF THE INVENTIONAccordingly, in order to overcome the above-mentioned shortcomings in the prior art, the object of the invention is to provide a conductive particle with phosphoric acid for a positive or negative electrode. An amorphous carbon layer on the outer surface of the ceramic particle prevents excessive volume expansion of the conductive particle and thus protects it from cracks. The amorphous carbon layer is composed of a high conductivity and increases the electric conductivity of the conductive particle. In order to avoid the difficulties of lithium ion conduction due to an excessive thickness of the amorphous carbon layer, the amorphous carbon layer additionally contains lithium fluoride particles which serve as bridges for the lithium ion channels and thus bring about better lithium ion conductivity.BRIEF DESCRIPTION OF THE DRAWINGSFig. 1 shows the structure of the conductive particle of the invention in cross section. FIG. 2 shows the structure of the conductive particle and the lithium fluoride particles of the invention in cross section. Fig. 3 schematically shows an application of the invention. Figure 4 schematically shows the composite particle of the invention.DETAILED DESCRIPTION OF THE INVENTIONFor a better understanding of the invention by those skilled in the art, a detailed description follows. However, these descriptions and the accompanying drawings are merely for understanding the objects, features and characteristics of the invention to those skilled in the art and do not limit the scope and spirit of the invention as defined in the appended claims.Referring to Figs. 1 to 4, the invention provides a conductive particle 40 containing phosphoric acids for a positive or negative electrode. The conductive particle 40 is used in an electrode 10 of a solid-state or semi-solid-state battery. Referring to FIG. 3, the electrode 10 includes an electrode substrate 11 as a support of the electrode material, and an electrode bulk layer 13 applied to the electrode substrate 11. The weight proportion of the conductive particles 40 in the electrode mass layer 13 is 0.1-1% by weight. The particle size of each conductive particle 40 is less than 200 nm.Referring to FIG. 1, the conductive particle 40 includes the following elements:A ceramic particle 30 has a particle size of less than 150 nm. The ceramic particle 30 has a high lithium ion conductivity and serves to conduct lithium ions through the electrode 10 and thus distribute lithium ion channels in the electrode 10. As a result, the lithium ion channels are uniformly distributed in the electrode. Side reactions with the electrode mass, which are formed by an abnormal deposition of lithium ions in the electrode slurry, are avoided.The ceramic particle 30 is made of at least one of the following materials: a first ceramic oxide or phosphate which conducts lithium ions, and a second oxide having a garnet or perovskite structure and sulfide. The lithium ion conductivity of the first ceramic oxide or phosphate is above 10 -3 cm 2 / s.The first ceramic oxide or phosphate may be LATP (lithium aluminum titanium phosphate) having a NASICON structure (sodium (Na) super-ion conductor), LAGP (lithium aluminum germanium phosphate), or lithiophosphate (Li 3 PO 4). The second oxide may be LLZO (Li 7 La 3 Zr 2 O 12, lithium lanthanum zirconium oxide) or LLTO (lithium lanthanum titanium oxide). The sulfide may be LGPS (lithium germanium phosphorus sulfide). The ceramic particle 30 may be formed by combining the above materials in any ratio.The ceramic particle 30 may be made of at least one of LLZO (Li 7 La 3 Zr 2 O 12), Ga-LLZO (gallium-doped LLZO), Cu-LLZO (copper-doped LLZO), Ta-LLZO (tantalum-doped LLZO), Sr-LLZO (strontium-doped LLZO), and Al-LLZO (aluminum-doped LLZO).When the ceramic particle 30 is formed by LAGP or LATP, the LAGP or LATP is selected from Li 1+x Al x A 2-x( PO 4)3 or Li 1+x+y Al x A 2-x-y-z M y N z( PO 4)3 where 0.1≤x≤0.8, 0≤y≤0.2, 0≤z≤0.2, A is germanium (Ge) or titanium (Ti), M is a trivalent cation (such as scandium cation (Sc3+), Yttrium cation (Y 3+), gallium cation (Ga 3+), indium cation (In 3+) or lanthanum cation (La 3+)) and N is tetravalent cation (such as zirconium cation (Zr 4+), silicon cation (Si 4+) or tin cation (Sn 4+)).An amorphous carbon layer 50 is deposited on the outer surface of the ceramic particle 30. Its radial thickness is less than 10 nm. The amorphous carbon layer 50 has high conductivity to prevent excessive volume expansion of the ceramic particle 30 upon lithium ion filling, thereby protecting the conductive particle 40 from breakage.The amorphous carbon layer 50 contains amorphous carbons 52. the amorphous carbons 52 are made of at least one of the following elements:(i) Hard or soft carbons formed by deesterification in sintering organic resins or organic carbohydrates.(ii) Amorphous carbons formed by the reaction of an organic compound under a reducing atmosphere. The organic compound is selected from carbohydrates (such as monosaccharides, disaccharides, oligosaccharides or polysaccharides), water soluble fibers and amino acid polymers. Preferably, the organic compound is a carbonaceous compound having at least one of nitrogen, fluorine, phosphorus and sulfur. Nitrogen, fluorine, phosphorus, and sulfur are doped into the carbon by a reduction reaction, thereby increasing the electrical conductivity of the conductive particle 40.(iii) Amorphous carbons formed by dehydration of carbohydrates.(iv) Amorphous carbons having carbon skeletons and functional groups formed by dehydration of water-soluble fibers.(v) Amorphous carbons having straight-chain or side-chain carbon skeletons containing doping elements formed by dehydration of amino acid polymers.A plurality of graphene sheets 54 are incorporated into the amorphous carbon layer 50. Each graphene sheet 54 is made of multilayer graphene (FLG) having 2-10 graphene layers. The size of each graphene sheet 54 is less than 500 nm. Each graphene sheet 54 has a sheet structure. The graphene sheets 54 form a multilayer structure enclosing the outer side of the ceramic particle 30.A plurality of first carbon nanotubes (CNTs) 56 are incorporated into the amorphous carbon layer 50. Each of the first carbon nanotubes 56 is less than 1 μm long. The first carbon nanotubes 56 are distributed in the spaces between the graphene layers 54 and the ceramic particle 30 and in the spaces between different graphene layers 54 and serve as bridges between the graphene layers 54 and the ceramic particle 30.The ratio of the weight of the ceramic particle 30 to the weight of the amorphous carbon layer 50 is 99.5:0.5. the ratio of the total weight of the graphene layers 54 to the total weight of the first carbon nanotube 56 is 4:1.Referring to Figure 2, the invention also comprises:In the amorphous carbon layer 50, a plurality of lithium fluoride particles (LiF) 55 are dispersed. Since the efficiency of passage of the lithium ions through the conductive particle 40 is influenced by the thickness of the amorphous carbon layer 50, the lithium fluoride particles 55 may serve as bridges to conduct the lithium ions through the conductive particle 40. The lithium fluoride particles (LiF) 55 form a plurality of island-shaped structures.The particle size of each lithium fluoride particle 55 is less than 5 nm. The ratio of the weight of the ceramic particle 30 to the total weight of the lithium fluoride particles 55 is 99.9-99.95:0.1-0.05.According to FIG. 4, the outer side of the conductive particle 40 is additionally coated with a plurality of second carbon nanotubes 42, as a result of which a composite particle 45 is formed. Each of the second carbon nanotubes 42 is between 1 and 3 μm long.Carbon nanotubes have a high conductivity. The composite particle 45 has a crumpled structure. The second carbon nanotubes 42 increase the electrical conductivity and thus enable electron conduction on the conductive particle 40. the second carbon nanotubes 42 also conduct lithium ions, whereby the lithium ions can be transported between different conductive particles 40 in the electrode 10, which increases the electrical conductivity and the ion conductivity of the electrode 10.The ratio of the total weight of the second carbon nanotubes 42 to the weight of the conductive particle 40 is 1:99 to 0.2:99.8.Thus, in a solid or semi-solid battery, a conductive particle with phosphoric acids is used for a positive or negative electrode. The conductive particle comprises a ceramic particle that conducts lithium ions through the electrode and thus creates uniformly distributed lithium ion channels in the electrode. The outer surface of the ceramic particle is coated with an amorphous carbon layer. The amorphous carbon layer has a specific conductivity to prevent excessive volume expansion of the ceramic particle. A plurality of graphene layers are incorporated into the amorphous carbon layer. A plurality of first carbon nanotubes (CNTs) are incorporated into the amorphous carbon layer. The first carbon nanotubes serve as bridges between the graphene layers and the ceramic particle.In describing the invention, it will be apparent that the same may be modified in a variety of ways. Such variations do not constitute a departure from the spirit of the invention, and all modifications obvious to one skilled in the art are intended to be included within the scope of the following claims.

Claims

A conductive particle with phosphoric acids for a positive or negative electrode; wherein the positive or negative electrode is used in a solid or semi-solid state battery; the conductive particle comprises: a ceramic particle that serves to conduct lithium ions through the positive or negative electrode and cause the positive or negative electrode to have lithium ion channels distributed uniformly; an amorphous carbon layer on the outer surface of the ceramic particle; the amorphous carbon layer has a specific conductivity to prevent excessive volume expansion of the ceramic particle when filled with lithium ions; a plurality of graphene layer layers incorporated in the amorphous carbon layer; each of the graphene layer layers has a layered structure; the graphene layer layers form a multilayer structure enclosing the outer surface of the ceramic particle; and a plurality of first carbon nanotubes (CNT) incorporated in the amorphous carbon layer; the first carbon nanotube is distributed in the spaces between the graphene layers and the ceramic particle and in the spaces between different graphene layers and serves as a bridge between the graphene layers and the ceramic particle.The conductive particle according to claim 1, further comprising a plurality of lithium fluoride particles (LiF) dispersed in the amorphous carbon layer. The lithium fluoride particles serve as bridges for conducting the lithium ions through the conductive particle. The lithium fluoride particles (LiF) form a plurality of island-shaped structures.The conductive particle according to claim 1, wherein the ceramic particle is composed of at least one of "a first ceramic oxide or phosphate capable of conducting lithium ions", "a second oxide having a garnet or perovskite structure", and / or sulfide. The lithium ion conductivity of the first ceramic oxide or phosphate is greater than 10-3 cm 2 / s.The conductive particle according to claim 3, wherein the first ceramic oxide or phosphate is selected from LATP (lithium aluminum titanium phosphate) having a NASICON structure (sodium (Na) super-ion conductor), LAGP (lithium aluminum germanium phosphate), or lithiophosphate (Li 3 PO 4).The conductive particle according to claim 4, wherein the ceramic particle is made of LAGP or LATP, and LAGP or LATP is selected from Li 1+x Al x A 2-x( P0 4)3 or Li 1+x+y Al x A 2-x-y-z M y N z( PO 4)3 and 0.1 ≤ x ≤ 0.8, 0 ≤ y ≤ 0.2, 0 ≤ z ≤ 0.

2. A is germanium (Ge) or titanium (Ti), M is a trivalent cation and N is a tetravalent cation.The conductive particle according to claim 5, wherein M is selected from scandium cation (Sc 3+), yttrium cation (Y 3+), gallium cation (Ga 3+), indium cation (In 3+) and lanthanum cation (La 3+).The conductive particle of claim 2, wherein the particle size of each lithium fluoride particle is less than 5 nm; and the ratio of the weight of the ceramic particle to the total weight of the lithium fluoride particles is 99.9-99.95:0.1-0.05.The conductive particle of claim 1, wherein the radial thickness of the amorphous carbon layer is less than 10 nm; and the particle size of the conductive particle is less than 200 nm.The conductive particle of claim 1, wherein the ceramic particle has a particle size of less than 150 nm; and each of the first carbon nanotubes has a length of less than 1 μm.The conductive particle according to claim 1, wherein the amorphous carbon layer contains amorphous carbons; and the amorphous carbons are made of at least one of the following materials: (a) hard carbon or soft carbon formed by deesterification in sintering organic resins or organic carbohydrates; (b) amorphous carbon formed by the reaction of an organic compound under reducing atmosphere; (c) amorphous carbon formed by dehydration of carbohydrates; (d) amorphous carbon having carbon skeletons and functional groups formed by dehydration of water-soluble fibers; and (e) amorphous carbon having carbon skeletons having straight chains or side chains containing doping elements formed by dehydration of amino acid polymers.The conductive particle of claim 10, wherein the organic compound is a carbohydrate selected from monosaccharides, disaccharides, oligosaccharides, polysaccharides, water soluble fibers, and amino acid polymers.The conductive particle according to claim 10, wherein the organic compound is a carbon-containing compound containing at least one of nitrogen, fluorine, phosphorus, and sulfur.The conductive particle of claim 1, wherein each of the graphene layer sheets is a multilayer graphene (FLG) having 2-10 graphene layers; each of the graphene layer sheets has a layered structure; and the size of each of the graphene layer sheets is less than 500 nm.The conductive particle of claim 1, wherein the ratio of the weight of the ceramic particle to the weight of the amorphous carbon layer is 99.5:0.5; and the ratio of the total weight of the graphene layer layers to the total weight of the first carbon nanotube is 4:1.The conductive particle according to claim 1, wherein an outer side of the conductive particle is additionally coated with a plurality of second carbon nanotubes to form a composite particle; the composite particle has a thread-ball-like structure; and the second carbon nanotubes serve to increase the electrical conductivity of the positive or negative electrode; and wherein each of the second carbon nanotubes has a length between 1 and 3 μm; and the ratio of the total weight of the second carbon nanotubes to the weight of the conductive particle is 1:99 to 0.2:99.8.The conductive particle according to claim 5, wherein N is selected from zirconium cation (Zr 4+), silicon cation (Si 4+) and tin cation (Sn 4+).

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