Composite electrode particles with silicon, carbon and zinc oxide layer

Abstract

Composite electrode particles coated with silicon, carbon, and zinc oxide; the composite electrode particle is used in an electrode of a solid-state or semi-solid-state battery; the composite electrode particle comprises: a porous carbon particle with a multitude of holes; The silicon layer is applied to an outer surface of the porous carbon particle; the silicon layer is a continuously thin film formed from a silicon material; and the silicon material of the silicon layer is additionally filled into the holes of the porous carbon particle; The carbon layer is an amorphous carbon layer coated onto an outer surface of the silicon layer; the amorphous carbon layer has a continuous structure formed from amorphous carbon; the amorphous carbon layer serves to prevent expansion of the composite electrode particle in order to prevent the composite electrode particle from bursting due to volume expansion when the lithium ions fill the silicon layer; and a zinc oxide layer (ZnO) coated on the outer surface of the amorphous carbon layer; the zinc oxide layer constitutes a continuously thin film formed from zinc oxide; wherein the zinc oxide layer exhibits a specific conductivity and is a continuous dense layer with metallic hardness properties, a specific ductility and integrity.

Description

FIELD OF THE INVENTION

[0001] The invention relates to a battery electrode material and in particular to a composite electrode particle having a silicon, carbon and zinc oxide layer applied thereto. BACKGROUND OF THE INVENTION

[0002] A typical battery comprises a positive and a negative electrode. The negative electrode of a solid-state or semi-solid-state battery comprises a negative electrode substrate and a negative electrode mass layer. The negative electrode mass layer comprises a negative electrode mass and a multitude of negative electrode particles. The negative electrode particles must be either additionally conductive or electrically conductive to allow free electrons to migrate through the negative electrode mass without dissipating too much energy due to internal resistance.

[0003] The negative electrode particles are distributed throughout the negative electrode mass, and one outer surface of each negative electrode particle is coated with silicon particles. During the battery's chemical reaction, lithium ions penetrate the silicon particles and increase the overall size of these silicon particles, which can increase by up to 400 times the original size of the silicon particle. This significantly changes the size of the negative electrode particles. Such a significant increase in size destroys the electrode particles, inevitably leading to a deterioration in battery performance. SUMMARY OF THE INVENTION

[0004] To overcome the above-mentioned deficiencies in the current art, the object of the invention is to provide a composite electrode particle 40 coated with silicon, carbon, and zinc oxide. The silicon layer and the amorphous carbon layer are coated on the outer surface of the porous carbon particle to inhibit the expansion of the composite electrode particle and thus prevent the composite electrode particle from rupturing. The amorphous carbon layer has high conductivity and serves to inhibit the expansion of the composite electrode particle and thus prevent the composite electrode particle from rupturing due to volume expansion when the lithium ions fill the silicon layer. The outer surface of the amorphous carbon layer is also coated with zinc oxide, which has metallic hardness properties and high ductility.As lithium ions fill the silicon layer and expand the silicon layer, the zinc oxide layer serves to protect the internal structure through its high ductility. As a result, the above multilayer coating structure can greatly reduce the fracture rate of the composite electrode particle. SHORT DESCRIPTIONS OF THE ILLUSTRATIONS Fig. shows a cross-sectional view depicting the structure of the composite electrode particle of the invention. Fig. shows a schematic view depicting the porous carbon particle of the invention. Fig. shows a schematic view depicting the carbon nanotube coated composite electrode particle of the invention. Fig. shows a schematic view illustrating an application of the invention. Fig. shows a schematic view illustrating another embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION

[0005] With reference to the Fig. The invention provides a composite electrode particle 40 coated with silicon, carbon, and zinc oxide for use as a negative (-) electrode 10 of a solid-state or semi-solid-state battery. With reference to Fig. The negative electrode 10 comprises a negative electrode substrate 11 supporting the material of the negative electrode 10 and a negative electrode compound layer 13 coated on the negative electrode substrate 11. The negative electrode compound layer 13 comprises a plurality of composite electrode particles 40 and a negative electrode compound 12 containing a binder. A weight fraction of the composite electrode particles 40 in the negative electrode compound layer 13 is 90 wt% to 99 wt%. The size of each of the composite electrode particles 40 is 5 µm to 12 µm.

[0006] With reference to Fig. the composite electrode particle 40 comprises the following elements.

[0007] A porous carbon particle 30 has a plurality of holes 31 (as in Fig. shown). The size of the porous carbon particle 30 is 5 µm to 10 µm. The porous carbon particle 30 can be made of graphite.

[0008] A silicon layer 32 is applied to an outer surface of the porous carbon particle 30. The silicon layer 32 is a continuous thin film formed from a silicon material. The silicon material of the silicon layer 32 is also filled into the holes 31 of the porous carbon particle 30. The thickness of the silicon layer 32 is less than 15 nm. The ratio of the weight of the silicon layer 32 to the weight of the porous carbon particle 30 is 1:9 to 1:12.

[0009] The carbon layer of the invention is an amorphous carbon layer 36 deposited on an outer surface of the silicon layer 32. The amorphous carbon layer 36 has a continuous structure (thin film structure) formed from amorphous carbon. The radial thickness of the amorphous carbon layer 36 is 10 nm to 20 nm. The amorphous carbon layer 36 has high conductivity and serves to prevent expansion of the composite electrode particle 40, thereby preventing the composite electrode particle 40 from cracking due to volume expansion when lithium ions fill the silicon layer 32. The amorphous carbon of the amorphous carbon layer 36 is selected from hard carbon or soft carbon, which is formed by deesterification during sintering of organic resins, and hard carbon or soft carbon, which is formed by deesterification during sintering of organic carbohydrates.

[0010] During the battery's chemical reaction, lithium ions penetrate the silicon layer 32 and enlarge the silicon layer 32, with the increased size being up to 400 times the original size of the silicon layer 32. Therefore, the size of the composite electrode particles 40 changes drastically. To prevent the composite electrode particles 40 from bursting due to the enlargement of the silicon layer 32, the outer surface of the silicon layer 32 is coated with an amorphous carbon layer 36 to protect the composite electrode particles 40 from bursting.

[0011] A zinc oxide (ZnO) layer 37 is applied to an outer surface of the amorphous carbon layer 36. The zinc oxide layer 37 is a continuous thin film consisting of zinc oxide. The porous carbon particles 30, the silicon layer 32, the amorphous carbon layer 36, and the zinc oxide layer 37 form the composite electrode particles 40. The radial thickness of the zinc oxide layer 37 is 8 nm to 12 nm. The zinc oxide layer 37 exhibits high conductivity and is a continuous, dense layer with metallic hardness properties, a specific high ductility, and integrity, which serves to protect the internal structure and maintain the integrity of the composite electrode particle 40.

[0012] Referring to Fig. An outer surface of the composite electrode particle 40 is further coated with a plurality of carbon nanotubes 42 to form a carbon nanotube-coated composite electrode particle 45. The size of each of the carbon nanotubes 42 is less than 5 µm.

[0013] The carbon nanotubes 42 have a high conductivity. The carbon nanotube-coated composite electrode particle 45 has a yarn-ball-like structure (as shown in Fig. (shown). The carbon nanotubes 42 serve to increase the electrical conductivity and allow the electrons on the composite electrode particle 40 to become conductive. The carbon nanotubes 42 also serve to conduct the lithium ions, allowing the lithium ions to be transferred between different composite electrode particles 40 in the electrode, which increases the electrical conductivity and ionic conductivity of the electrode.

[0014] The ratio of the total weight of the carbon nanotubes 42 to the weight of the composite electrode particle 40 is 1:99 to 0.2:99.8.

[0015] Fig. shows a further embodiment of the invention in which a layer 38 of aluminum oxide (Al2O3) is applied to an outer side of the composite electrode particle 40. The aluminum oxide layer 38 is a continuous thin film of aluminum oxide and is applied to an outer surface of the zinc oxide layer 37 of the composite electrode particle 40. A radial thickness of the aluminum oxide layer 38 is less than 5 nm. The aluminum oxide layer 38 serves to improve conductivity and electrolyte wetting. An outer surface of the aluminum oxide layer 38 is additionally coated with a plurality of carbon nanotubes 42 to form a carbon nanotube-coated composite electrode particle 45.

[0016] A composite electrode particle coated with a silicon layer, a carbon layer, and zinc oxide is used in an electrode of an all-solid-state or semi-solid-state battery. The composite electrode particle comprises a porous carbon particle having a plurality of holes. The silicon layer is coated on an outer surface of the porous carbon particle and is a continuous thin film formed from a silicon material. The carbon layer is an amorphous carbon layer coated on an outer surface of the silicon layer and is a continuous structure formed from amorphous carbon. The amorphous carbon layer serves to prevent expansion and tearing of the composite electrode particle. A zinc oxide layer is coated on an outer surface of the amorphous carbon layer and is a continuous structure formed from zinc oxide.

[0017] Having described the invention, it will be obvious that it may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope 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

[1] Composite electrode particles coated with silicon, carbon and zinc oxide; the composite electrode particle is used in an electrode of a solid-state or semi-solid-state battery; the composite electrode particle comprises: a porous carbon particle with a multitude of holes; The silicon layer is coated on an outer surface of the porous carbon particle; the silicon layer is a continuous thin film formed from a silicon material; and the silicon material of the silicon layer is additionally filled into the holes of the porous carbon particle; the carbon layer is an amorphous carbon layer coated on an outer surface of the silicon layer; the amorphous carbon layer has a continuous structure formed from amorphous carbon; the amorphous carbon layer serves to prevent expansion of the composite electrode particle to prevent bursting of the composite electrode particle due to volume expansion when the lithium ions fill the silicon layer; and a zinc oxide (ZnO) layer coated on an outer surface of the amorphous carbon layer; the zinc oxide layer is a continuous thin film formed from zinc oxide; the zinc oxide layer has a specific conductivity and is a continuous dense layer with metallic hardness properties, a specific ductility, and integrity. [2] The composite electrode particles according to claim 1, wherein a size of the porous carbon particle is 5 µm to 10 µm. [3] The composite electrode particles according to claim 1, wherein a thickness of the silicon layer is less than 15 nm. [4] The composite electrode particles according to claim 1, wherein a ratio of a weight of the silicon layer and a weight of the porous carbon particle is 1:9 to 1:

12. [5] The composite electrode particles according to claim 1, wherein a radial thickness of the amorphous carbon layer is 10 nm to 20 nm. [6] Composite electrode particles according to claim 1, wherein the amorphous carbon of the amorphous carbon layer is selected from hard carbon or soft carbon which is formed by deesterification during sintering of organic resins and hard carbon or soft carbon which is formed by deesterification during sintering of organic carbohydrates. [7] The composite electrode particles according to claim 1, wherein the radial thickness of the zinc oxide layer is 8 nm to 12 nm. [8] The composite electrode particle according to claim 1, wherein the composite electrode particle is used in a negative electrode of the solid or semi-solid mass. [9] The composite electrode particle according to claim 1, wherein an outer side of the composite electrode particle is further coated with a plurality of carbon nanotubes to form a carbon nanotube-coated composite electrode particle. [10] The composite electrode particle according to claim 9, wherein the size of each of the carbon nanotubes is less than 5 µm; and the carbon nanotube-coated composite electrode particle has a yarn ball-like structure. [11] The composite electrode particle according to claim 9, wherein the ratio of the total weight of the carbon nanotubes to the weight of the composite electrode particle is 1:99 to 0.2:99.

8. [12] The composite electrode particle according to claim 1, wherein an outer surface of the composite electrode particle is coated with a layer of aluminum oxide (Al2O3); and the aluminum oxide layer is a continuous thin film formed of aluminum oxide and coated on an outer surface of the zinc oxide layer of the composite electrode particle. [13] The composite electrode particles according to claim 12, wherein a radial thickness of the aluminum oxide layer is less than 5 nm. [14] The composite electrode particle according to claim 12, wherein an outer surface of the aluminum oxide layer is further coated with a plurality of carbon nanotubes to form a carbon nanotube-coated composite electrode particle.

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