Composite electrode particles coated with granular silicon structure, carbon layer and zinc oxide

Abstract

Composite electrode particles coated with a granular silicon structure, a carbon layer, 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 carbon layer is an amorphous carbon layer applied to an outer surface of the porous carbon particle; the amorphous carbon layer exhibits a continuous structure formed from amorphous carbon; the amorphous carbon layer serves to prevent expansion of the composite electrode particle and thus to prevent the composite electrode particle from bursting as lithium ions accumulate on the composite electrode particle; A large number of silicon particles are dispersed within the amorphous carbon layer; an outer surface of some of the silicon particles is coated with a silicon oxide layer, which consists of SiO₂. x is formed where 0 < x ≤ 2; and The zinc oxide layer (ZnO) is applied to the outer surface of the amorphous carbon layer; the zinc oxide layer is a continuous structure formed from a multitude of zinc oxide particles; and wherein, as the lithium ions fill the silicon particles and expand the size of the silicon particles, the zinc oxide layer serves to protect the composite electrode particle by a specific ductility in order to preserve its integrity.

Description

FIELD OF THE INVENTION

[0001] The invention relates to battery electrode material and, more particularly, to a composite electrode particle coated with a granular silicon structure, a carbon layer, and zinc oxide. 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 contains a negative electrode mass and a multitude of negative electrode particles. The negative electrode particles must be either additionally conductive or electrically conductive so that free electrons can 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 size of the silicon particles, which can be up to 400 times the original size of the silicon particle. Therefore, the size of the negative electrode particles changes dramatically, and such a drastic increase in size destroys the electrode particles, leading to a deterioration in battery performance. SUMMARY OF THE INVENTION

[0004] To overcome the above-mentioned deficiencies in the current state of the art, the object of the invention is to provide a composite electrode particle coated with a granular silicon structure, a carbon layer, and zinc oxide. The silicon particles and the amorphous carbon layer are located on the outer surface of the porous carbon particle. The silicon particles coated with the silicon oxide layer have a lower thermal expansion coefficient and high bonding capacity, thereby inhibiting the expansion of the composite electrode particle and preventing it from cracking. The amorphous carbon layer exhibits high conductivity and serves to inhibit the expansion of the composite electrode particle, preventing it from cracking due to volume expansion once the lithium ions fill the composite electrode particle.The outer surface of the amorphous carbon layer is also coated with a zinc oxide layer, which exhibits high conductivity and ductility similar to metals. As lithium ions fill the silicon particles and increase their size, the zinc oxide layer serves to protect the internal structure through its high ductility. As a result, the multilayer coating structure described above can significantly reduce the fracture rate of the composite electrode particles. BRIEF DESCRIPTION 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 complete structure and a partial structure of the composite electrode particle of the invention. Fig. shows a schematic view depicting the silicon particles and the silicon oxide layer of the invention. Fig. shows a schematic view showing the carbon nanotube coated composite electrode particle of the invention. Fig. shows a schematic view illustrating an application of the invention. DETAILED DESCRIPTION OF THE INVENTION

[0005] With reference to the Fig. The invention provides a composite electrode particle 40 coated with a granular silicon structure, a carbon layer, and zinc oxide for use in 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 slurry layer 13 coated on the negative electrode substrate 11. The negative electrode slurry layer 13 comprises a plurality of composite electrode particles 40 and a negative electrode slurry 12 containing a binder. A weight fraction of the composite electrode particles 40 in the negative electrode slurry 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] 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] The carbon layer of the invention is an amorphous carbon layer 36 coated on an outer surface of the porous carbon particle 30. The amorphous carbon layer 36 has a continuous structure (a film layer with a smooth outer surface) composed of 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 and tearing of the composite electrode particle 40 due to volume expansion once the lithium ions fill the composite electrode particle 40. The amorphous carbon of the amorphous carbon layer 36 is selected from hard carbon or soft carbon, which is formed by deesterification during the sintering of organic resins or organic carbohydrates.The amorphous carbon layer 36 serves to protect the composite electrode particle 40.

[0009] A plurality of silicon particles 32 are dispersed within the amorphous carbon layer 36. Referring to the Fig. an outer surface of a part of the silicon particles 32 is coated with a silicon oxide layer 322 consisting of SiO xis formed, where 0 < x ≤ 2. The plurality of silicon particles 32 form a discontinuous structure, wherein the silicon particles 32 on an outer side of the amorphous carbon layer 36 form an island-shaped structure having a plurality of protruding portions, the silicon particles 32 on an inner side of the amorphous carbon layer 36 are attached to the outer surface of the porous carbon particle 30, and the silicon particles 32 are slurried between the outer and inner sides of the amorphous carbon layer 36 in the amorphous carbon layer 36 without contacting the porous carbon particle 30.

[0010] The size of each of the silicon particles 32 is 10 nm to 30 nm. The thickness of the silicon oxide layer 322 is less than 3 nm. The silicon oxide layer 322 is formed by grinding or combustion during the production of the composite electrode particle 40. The ratio of the total weight of the silicon particles 32 to the weight of the porous carbon particle 30 is 1:9 to 1:12.

[0011] During the battery's chemical reaction, lithium ions penetrate the silicon particles 32 and increase the size of the silicon particles 32, which can be up to 400 times the original size of the silicon particles 32. Therefore, the size of the composite electrode particles 40 changes dramatically. The holes 31 of the porous carbon particles 30 serve to accommodate the expanded silicon particles 32.

[0012] The conductivity of the silicon oxide layer 322 is lower than that of the silicon particle 32. When the lithium ions pass through the silicon particles 32 and increase the size of the silicon particles 32, the enormous size expansion of the silicon particles 32 damages the composite electrode particle 40. The thermal expansion coefficient of the silicon oxide layer 322 is lower than that of the silicon particle 32, and the bonding ability of the silicon oxide layer 322 is better than that of the silicon particle 32, which inhibits the expansion of the composite electrode particle 40 and prevents the composite electrode particle 40 from rupturing.

[0013] A zinc oxide (ZnO) layer 37 is deposited on an outer surface of the amorphous carbon layer 36. The zinc oxide layer 37 is a continuous structure (a film layer with a smooth outer surface) composed of a plurality of zinc oxide particles 38. The porous carbon particle 30, the amorphous carbon layer 36, the silicon particles 32, and the zinc oxide layer 37 form the composite electrode particle 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 a specific ductility similar to that of metals. When lithium ions fill the silicon particles 32 and increase the size of the silicon particles 32, the high ductility of the zinc oxide layer 37 serves to protect the internal structure and maintain the integrity of the composite electrode particle 40.

[0014] With reference 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.

[0015] 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 electrical conductivity so that electrons can be conducted on the composite electrode particle 40. The carbon nanotubes 42 also serve to conduct lithium ions so that the lithium ions can be conducted between different composite electrode particles 40 in the electrode, which increases the electrical conductivity and ionic conductivity of the electrode.

[0016] 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.

[0017] A composite electrode particle coated with a granular silicon structure, a carbon layer, and a zinc oxide layer is used in an electrode of an all-solid-state or semi-solid-state battery. The composite electrode particle has a porous carbon particle with numerous holes. The carbon layer is an amorphous carbon layer coated on an outer surface of the porous carbon particle. The amorphous carbon layer exhibits a continuous structure, which serves to prevent the composite electrode particle from expanding. A plurality of silicon particles are dispersed within the amorphous carbon layer. An outer surface of a portion of the silicon particles is coated with a silicon oxide layer.The zinc oxide layer is applied to an outer side of the amorphous carbon layer and shows a continuous structure, which serves to protect and maintain the integrity of the composite electrode particle.

[0018] 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 a granular silicon structure, a carbon layer, 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 carbon layer represents an amorphous carbon layer coated on an outer surface of the porous carbon particle; the amorphous carbon layer exhibits a continuous structure formed from amorphous carbon; the amorphous carbon layer serves to prevent expansion of the composite electrode particle and thus prevent bursting of the composite electrode particle when lithium ions accumulate on the composite electrode particle. a plurality of silicon particles are dispersed within the amorphous carbon layer; an outer surface of a portion of the silicon particles is coated with a silicon oxide layer consisting of SiO x is formed, where 0 < x ≤ 2; and The zinc oxide (ZnO) layer is coated on an outer surface of the amorphous carbon layer; the zinc oxide layer is a continuous structure formed from a plurality of zinc oxide particles; and wherein, when the lithium ions fill the silicon particles and expand the size of the silicon particles, the zinc oxide layer serves to protect the composite electrode particle by a specific ductility, thus preserving its integrity. [2] The composite electrode particles according to claim 1, wherein the plurality of silicon particles form a discontinuous structure, the silicon particles on an outer side of the amorphous carbon layer forming an island-like structure having a plurality of protruding portions, the silicon particles on an inner side of the amorphous carbon layer being attached to the outer surface of the porous carbon particle, and the silicon particles being foamed between the outer and inner sides of the amorphous carbon layer in the amorphous carbon layer without contacting the porous carbon particle. [3] The composite electrode particle according to claim 1, wherein the size of the porous carbon particle is 5 µm to 10 µm. [4] The composite electrode particles according to claim 1, wherein the size of each silicon particle is 10 nm to 30 nm; and the thickness of the silicon oxide layer is less than 3 nm. [5] The composite electrode particles according to claim 1, wherein the ratio of the total weight of the silicon particles and the weight of the porous carbon particle is 1:9 to 1:

12. [6] The composite electrode particles according to claim 1, wherein the radial thickness of the amorphous carbon layer is 10 nm to 20 nm. [7] The composite electrode particles according to claim 1, wherein the amorphous carbon of the amorphous carbon layer is selected from hard carbon or soft carbon formed by deesterification upon sintering of organic resins or organic carbohydrates. [8] The composite electrode particles according to claim 1, wherein a radial thickness of the zinc oxide layer is 8 nm to 12 nm. [9] The composite electrode particle according to claim 1, wherein the composite electrode particle is used in a negative electrode of the solid-state or semi-solid-state battery. [10] The composite electrode particle according to claim 1, wherein an outer side of the composite electrode particle is coated by a plurality of carbon nanotubes to form a carbon nanotube-coated composite electrode particle. [11] The composite electrode particle according to claim 10, wherein a 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. [12] The composite electrode particle according to claim 10, wherein a ratio of a total weight of the carbon nanotubes and a weight of the composite electrode particle is 1:99 to 0.2:99.8.

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