LCO cathode particles coated with oxide and carbon nanotubes

Abstract

To provide an LCO positive electrode particle coated with an oxide and a carbon nanotube.SOLUTION: The LCO cathode particle 200 coated with the oxide and the carbon nanotube 30 is used for a cathode of solid-state or solid-state batteries. The positive electrode particle 200 includes a composite LCO particle containing an LCO (lithium cobalt oxide) large particle 22 having an irregular cubic shape, and a plurality of LLZO large particles 24 and a plurality of LLZO small particles 26 covering the outer surface of the LCO large particle 22. A first side 1LLZO dielectric layer is formed between the bottom of each of the LLZO large particles 24 and the LCO large particles 22. A first 2LLZO dielectric layer is formed between the bottom of each of the small LLZO particles 26 and the large LCO particles 22. The outer periphery of the composite LCO particle further has a plurality of short-chain carbon nanotubes and a plurality of long-chain carbon nanotubes 34 having different sizes and covering the entire composite LCO particle.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to cathode particles, and more particularly to LCO cathode particles coated with oxide and carbon nanotubes. [Background technology]

[0002] A battery is composed of a positive electrode and a negative electrode. The negative electrode of a battery is the positive electrode within the battery. The positive electrode mainly comprises a positive electrode substrate and a positive electrode slurry layer coated on the positive electrode substrate. The positive electrode slurry layer includes a positive electrode slurry with a binder and a plurality of positive electrode particles. Positive electrode particles are mainly used in the positive electrodes of general solid-state or solid-state batteries. Positive electrode particles must have guiding or conductivity properties to allow free electrons to migrate in the positive electrode slurry and prevent excessive energy consumption due to internal electrical resistance, thereby achieving the purpose of effective conductivity. Therefore, when manufacturing positive electrode particles, it is necessary to consider using specific conductive materials to adjust the conductivity of the positive electrode particles. Summary of the Invention [Problem to be solved by the invention]

[0003] The material of the conventional positive electrode particles is selected from LCO (lithium cobalt oxide), LMFP (lithium manganese iron phosphate), etc., or a mixture thereof, and the positive electrode particles are distributed in the positive electrode slurry. Although there are many techniques in the prior art to improve the guiding ability of the positive electrode particles to lithium ions, the current lithium battery still lacks the conductive ability for practical use.

[0004] Thus, the present invention provides a novel design that has higher capacitance and conductivity than conventional solid-state battery cathodes, thereby further enhancing the effectiveness of the battery.

[0005] The present invention has been made in view of the above circumstances, and aims to solve the above problems, namely, to provide LCO positive electrode particles coated with an oxide and carbon nanotubes. [Means for solving the problem]

[0006] To address the above-mentioned challenges, one embodiment of the present invention, an oxide- and carbon nanotube-coated LCO cathode particle, involves coating the surface of a large LCO particle with LLZO large and small particles and a dielectric layer to form a composite LCO particle, enhancing ionic conductivity and protection. Because electron transport and ion transport are interdependent, to address the issue of partial reduced electronic conductivity due to the ceramic nature of the oxide, the present invention coats the outer surface of the composite LCO particle with an electron-conducting medium, i.e., a conductive network formed by combining carbon nanotubes of various lengths. Short-chain carbon nanotubes can provide short-distance electron transport for electron conduction, facilitating the transport of lithium ions over short distances. Long-chain carbon nanotubes can provide electron transport between multiple LLZO large and small particles and between the composite LCO particle and other materials in the cathode substrate, forming a small electron transport system to facilitate ion transport and thereby improving electron and ion transport throughout the cathode. The coating effect of the carbon nanotubes and LLZO large and small particles reduces the likelihood of lithium ions being blocked by poor transport on the surface of the cathode. Furthermore, together with the electrolyte, they form lithium-consuming components such as a solid electrolyte interface (SEI). This extends the overall lifespan of the cathode material, i.e., improves cycling performance. Furthermore, the excellent lithium ion and electron transport system of the composite cathode material of the present invention achieves even higher multiplier performance. The improved ion and electron transport of the composite cathode reduces side reactions. Furthermore, the LLZO particles and the dielectric layer provide additional protection, making the entire cathode material less susceptible to reaction with the electrolyte, less susceptible to breakdown by the electrolyte at high voltages, and less susceptible to side reactions that occur after reaction with the cathode, thereby improving voltage resistance. This allows charging and discharging in the range of 4.7V to 4.9V, and further reduces high-pressure oxygen release and gas generation from the cathode, improving overall safety.

[0007] At least the following points will become clear from the description and drawings to be described later. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing an LCO cathode particle coated with an oxide and carbon nanotubes according to an embodiment of the present invention. FIG. [Figure 2] FIG. 1 shows an example of an LCO cathode particle coated with oxide and carbon nanotubes according to the present invention. [Figure 3] 1 is a schematic enlarged view showing a configuration according to an embodiment of the present invention. [Figure 4] FIG. 10 is a schematic enlarged view showing a configuration according to another embodiment of the present invention. [Figure 5] 1 is a schematic diagram showing a coating of a short-chain carbon nanotube according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be described below through embodiments of the invention, but the following embodiments do not limit the scope of the invention according to the claims. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0010] Hereinafter, the LCO positive electrode particles coated with oxide and carbon nanotubes according to the present invention will be specifically described with reference to FIGS.

[0011] In the LCO cathode particles coated with oxide and carbon nanotubes according to the present invention, the oxide is lithium lanthanum zirconium oxide (Li7La3Zr2O 12 ) or lithium lanthanum zirconium oxide doped with at least one metal element. The positive electrode particles 200 are used in a positive electrode 100 of a solid-state or solid-state battery (see FIG. 2). The positive electrode 100 includes a positive electrode substrate 10 and a positive electrode slurry layer 12 coated on the positive electrode substrate 10. The positive electrode slurry layer 12 includes a positive electrode slurry 14 having a binder, and a plurality of positive electrode particles 200 distributed in the positive electrode slurry 14. The total weight of the plurality of positive electrode particles 200 accounts for 92 wt% to 98 wt% of the weight of the positive electrode slurry layer 12.

[0012] The cathode particle 200 according to the present invention comprises a composite LCO particle 20, which further comprises an LCO (LiCoO, lithium cobalt oxide) large particle 22 having an irregular cubic shape, the LCO large particle 22 having a size ranging from 10 μm to 15 μm, and a plurality of LLZO large particles 24 and a plurality of LLZO small particles 26 covering the outer surface of the LCO large particle 22 (see FIG. 3). The lateral size of the LLZO large particle 24 (i.e., the size along the spherical surface of the corresponding composite LCO particle 20) ranges from 100 nm to 280 nm, and the lateral size of the LLZO small particle 26 (i.e., the size along the spherical surface of the corresponding LCO large particle 22) ranges from 50 nm to 100 nm. The LLZO large particles 24 and the LLZO small particles 26 cover the outer surfaces of the LCO large particles 22 by sintering, and after sintering, the vertical size becomes shorter and the horizontal size becomes wider, but the total volume does not change. The weight ratio of the plurality of LLZO large particles 24 to the LCO large particles 22 is in the range of 0.5 wt% to 0.8 wt%, and the weight ratio of the plurality of LLZO small particles 26 to the LCO large particles 22 is in the range of 0.1 wt% to 0.3 wt%.

[0013] Each of the LLZO large particles 24 and each of the LLZO small particles 26 are made of lithium lanthanum zirconium oxide (Li7La3Zr2O 12 , LLZO) or lithium lanthanum zirconium oxide doped with at least one metal element (e.g., Li 6.2 Ga 0.8 La3Zr2O 12 which may be gallium (Ga) doped lithium lanthanum zirconate, or aluminum (Al) or barium (Ba) doped lithium lanthanum zirconate).

[0014] 3, the profile of the longitudinal cross section (i.e., the cross section perpendicular to the horizontal direction) of each of the LLZO large particles 24 in the LCO large particle 22 is high in the center and has an arc-shaped protrusion with flat ends. A first LLZO dielectric layer 25 is formed between the bottom of each of the LLZO large particles 24 and the LCO large particle 22, and is used to guide lithium ions and protect the LCO large particle 22. The thickness of the intermediate layer of the first LLZO dielectric layer 25 is in the range of 2 nm to 12 nm.

[0015] The first LLZO dielectric layer 25 is primarily composed of lithium lanthanum zirconium oxide (LLZO) or lithium lanthanum zirconium oxide doped with at least one metal element, cobalt (Co) oxide, and a cobalt derivative (the cobalt is primarily from the outer layer of the LCO large grains 22). Its function is to provide lithium ions with favorable guide channels. The first LLZO dielectric layer 25 includes a first interface oxygen-deficient layer 251 and a first derivative layer 252, which are generated by the LLZO large grains 24 and the LCO large grains 22 during the sintering process. The first interface oxygen-deficient layer 251 contains lanthanum zirconate (La2Zr2O7) and lanthanum oxide (La2O3). The first derivative layer 252 contains lithium phosphate (Li3PO4), and the thicknesses of the first interface oxygen-deficient layer 251 and the first derivative layer 252 range from 1 nm to 10 nm. The first LLZO dielectric layer 25 helps connect the LCO large particles 22 and the LLZO large particles 24, forming a continuous interface. The first derivative layer 252 itself also has the ability to conduct lithium (Li) ions, but its ability is slightly inferior to that of the LLZO large particles 24. It is used as a connection layer for conducting ions and to protect the first interface oxygen-deficient layer 251. The first derivative layer 252 is derived from the surfaces of the LCO large particles 22, the LLZO large particles 24, and the LLZO small particles 26, forming a thin film.

[0016] 4, the profile of the longitudinal cross section (i.e., the cross section perpendicular to the horizontal direction) of each of the LLZO small particles 26 in the LCO large particle 22 has an arc-shaped protrusion shape with a high center and flat both ends. A second LLZO dielectric layer 27 is formed between the bottom of each of the LLZO small particles 26 and the LCO large particle 22, and the thickness of the intermediate layer of the second LLZO dielectric layer 27 is in the range of 2 nm to 12 nm.

[0017] The second LLZO dielectric layer 27 is primarily composed of lithium lanthanum zirconium oxide (LiZO) or lithium lanthanum zirconium oxide doped with at least one metal element, cobalt oxide, and a cobalt derivative (the cobalt is primarily derived from the outer layer of the LCO large particles 22). Its function is to provide lithium ions with favorable guide channels. The second LLZO dielectric layer 27 includes a second interface oxygen-deficient layer 271 and a second derivative layer 272 formed during the sintering process of the LLZO small particles 26 and the LCO large particles 22. The second interface oxygen-deficient layer 271 contains lanthanum zirconate (La2Zr2O7) and lanthanum oxide (La2O3), and the second derivative layer 272 contains lithium phosphate (Li3PO4). The thicknesses of the second interface oxygen-deficient layer 271 and the second derivative layer 272 range from 1 nm to 10 nm. The second LLZO dielectric layer 27 helps connect the LCO large particles 22 and the LLZO small particles 26, forming a continuous interface. The second derivative layer 272 also has the ability to conduct lithium ions, but is slightly less capable than the LLZO small particles 26. The second interface oxygen-deficient layer 271 serves as an ion-conducting connection layer and is used for protection. The second derivative layer 272 extends over the surfaces of the LCO large particles 22, the LLZO large particles 24, and the LLZO small particles 26, forming a thin film.

[0018] The LLZO small particles 26 are used to partially replace the LLZO large particles 24, increasing the surface coverage and reducing side reactions. The LLZO small particles 26 also function as lithium ion channels, transmitting ions and reducing the cost of coating the LCO large particles 22.

[0019] In the present invention, a plurality of the LLZO large particles 24 and a plurality of the LLZO small particles 26 are attached to the outer surface of the LCO large particle 22. The ion-guiding ability of each of the LLZO large particles 24 and the LLZO small particles 26 for lithium ions is much higher than that of the LCO large particles 22, and they are less likely to undergo side reactions with lithium ions. Therefore, when lithium ions pass through the positive electrode 100, they are guided by the dispersed plurality of LLZO large particles 24 and the dispersed plurality of LLZO small particles 26, and the lithium ion paths are dispersed. Therefore, in the present invention, lithium ions have more suitable paths, which greatly enhances the efficiency of the battery.

[0020] The large LLZO particles 24 cannot adequately cover the large LCO particles 22, resulting in many gaps. Therefore, the gaps between the large LLZO particles 24 must be filled with the small LLZO particles 26. In this way, stable process and surface coverage can be achieved using this mixing method.

[0021] The first dielectric layer 25 and the second dielectric layer 27 form connections between the LCO large particles 22, the LLZO large particles 24, and the LLZO small particles 26. The first dielectric layer 25 and the second dielectric layer 27 contain LaZrO and partially LaO. The more completely the LCO large particles 22 cover the LLZO large particles 24 and the LLZO small particles 26, the less exposed surface of the LCO large particles 22. This reduces the probability and amount of side reactions with the electrolyte or colloidal material, resulting in more stable cathode particles. The LaZrO also has lithium ion conductivity. Although its conductivity is lower than that of the LLZO large particles 24 and the LLZO small particles 26, it can act as an ion-conducting layer to help conduct lithium ions from the LCO large particles 22 to the LLZO large particles 24 and the LLZO small particles 26. The LLZO large particles 24 and the LLZO small particles act as high-speed tunnels for lithium ions, allowing lithium ions from the LCO large particles 22 to efficiently move in and out at high speed after reaching the LLZO large particles 24 and the LLZO small particles 26 via the first dielectric layer 25 and the second dielectric layer 27. Furthermore, the La2Zr2O7 itself has the inertia of a ceramic compound, which can reduce side reactions between the positive electrode and the electrolyte. In particular, the first dielectric layer 25 and the second dielectric layer 27 can provide an LCO material with damping and protection effects under high voltage conditions (>4.5V to 4.9V).

[0022] The LLZO large particles 24, the LLZO small particles 26, and the LCO large particles 22 all have a crystalline structure, and therefore have good overall stability and are not easily released or dissociated, thereby increasing the voltage of the entire battery.

[0023] The composite LCO particle 20 further has a plurality of carbon nanotubes (CNT) 30 of different sizes around its outer periphery, and the plurality of carbon nanotubes 30 coat the composite LCO particle 20 to form the positive electrode particle 200 (see FIG. 1).

[0024] The carbon nanotubes 30 comprise a plurality of short-chain carbon nanotubes 32 and a plurality of long-chain carbon nanotubes 34, each of which has a length ranging from 0.5 μm to 3 μm, and each of which has a length ranging from 8 μm to 12 μm. The weight ratio of the short-chain carbon nanotubes 32 to the long-chain carbon nanotubes 34 is 5:2, and the weight ratio of the carbon nanotubes 30 to the LCO large particles 22 is 0.01% to 0.5%.

[0025] 5, the short-chain carbon nanotubes 32 can straddle the corresponding LLZO large particles 24 and the LCO large particles 22, and can also straddle the corresponding LLZO small particles 26 and the LCO large particles 22. The long-chain carbon nanotubes 34 are used to coat the composite LCO particles 20, and by coating the LLZO large particles 24, the LLZO small particles 26, and the short-chain carbon nanotubes 32, the overall structural strength is enhanced and electronic conductivity is increased. The carbon nanotubes 30 are highly conductive and form a fuzzball-like morphology when attached to the composite LCO particles 20 (see FIG. 1).

[0026] The carbon nanotubes 30 are used to increase electron conductivity by forming conductive bridges around each of the LLZO large particles 24 and each of the LLZO small particles 26, allowing electrons to be conducted through the composite LCO particles 20. Because the carbon nanotubes 30 have extremely high conductivity, the carbon nanotubes 30 allow lithium ions to be conducted between the different LLZO large particles 24, the LLZO small particles 26, and the LCO large particles 22, thereby improving the conductivity of the entire cathode 100.

[0027] Each of the LLZO large particles 24 and each of the LLZO small particles 26 is composed of at least one of 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).

[0028] Preferably, each of the large LLZO particles 24 and each of the small LLZO particles 26 is Cu. a ,X b -LLZO, a ,X b LLZO is a lithium lanthanum zirconium oxide doped with copper and element X, where X is selected from Ga (gallium), Ta (tantalum), Sr (strontium), Ba (barium), and Al (aluminum), and a > 0 and b > 0. Preferably, a + b = 0.25 to 0.8, and a > 0.1. Although the technique of doping copper into LLZO is very difficult to use, it results in a more stable overall structure, smoother lithium ion channels, a faster sintering rate, and lower manufacturing costs. Furthermore, the formation of lithium carbonate (Li2CO3) when the LLZO material is exposed to air is reduced, which improves the surface stability of the entire material during sintering.

[0029] The advantage of the present invention is that the surfaces of large LCO particles are coated with LLZO large and small particles and a dielectric layer to form composite LCO particles, improving ion conduction and protection. Because electron transport and ion transport are interdependent, to address the issue of partial reduced electron conduction due to the ceramic nature of the oxides, the present invention coats the outer surfaces of the composite LCO particles with an electron-conducting medium, i.e., a conductive network formed by combining carbon nanotubes of various lengths. Short-chain carbon nanotubes can provide short-distance electron transport for electron conduction, facilitating the transport of lithium ions over short distances. Long-chain carbon nanotubes can provide electron transport between multiple LLZO large and small particles and between the composite LCO particles and other materials in the positive electrode substrate, forming a small electron transport system that promotes ion transport and improves electron and ion transport throughout the positive electrode. The coating effect of the carbon nanotubes and large and small LLZO particles makes it less likely that lithium ions will be blocked by poor transport on the surface of the positive electrode. Furthermore, together with the electrolyte, they form a lithium-consuming product, such as a solid electrolyte interface (SEI). The overall lifespan of the positive electrode particles is extended, i.e., the cycling performance is improved. Furthermore, the excellent lithium ion and electron transport system of the composite positive electrode particles according to the present invention allows for even higher multiplication performance. The improved ion and electron transport of the composite positive electrode reduces side reactions. Furthermore, the LLZO particles and the dielectric layer provide additional protection, making the entire positive electrode particle less susceptible to reaction with the electrolyte, less likely to be broken down by the electrolyte at high voltages, and less susceptible to side reactions that occur after reaction with the positive electrode, thereby improving voltage resistance. While enabling charging and discharging in the range of 4.7V to 4.9V, high-pressure oxygen release and gas generation from the positive electrode are further reduced, improving overall safety.

[0030] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above examples. It will also be apparent to those skilled in the art that such modifications and improvements can be made. It will also be apparent from the claims that such modifications and improvements can also be included within the technical scope of the present invention. [Explanation of symbols]

[0031] 10 Positive substrate 12 Positive electrode slurry layer 14 Positive electrode slurry 20 Composite LCO particles 22 Large LCO particles 24 LLZO large particles 25 First LLZO dielectric layer 26 LLZO small particles 27 Second LLZO dielectric layer 30 Carbon nanotubes 32 Short-chain carbon nanotubes 34 Long-chain carbon nanotubes 100 positive electrode 200 positive particles 251 First interface oxygen-deficient layer 252 1st derived layer 271 Second interface oxygen-deficient layer 272 Second derived layer

Claims

1. LCO cathode particles coated with an oxide and carbon nanotubes, the oxide being lithium lanthanum zirconium oxide (Li 7 La 3 Zr 2 O 12 ) or lithium lanthanum zirconium oxide doped with at least one metal element, and the positive electrode particles are used in the positive electrode of a solid-state battery or a solid-state battery, and the positive electrode particles comprise composite LCO particles, and the composite LCO particles are LCO (LiCoO) particles exhibiting irregular cubes. 2 a plurality of LLZO large particles and a plurality of LLZO small particles covering the outer surfaces of the LCO large particles, each of the LLZO large particles and each of the LLZO small particles being lithium lanthanum zirconium oxide (Li 7 La 3 Zr 2 O 12 a plurality of LLZO large particles and a plurality of LLZO small particles, each of which is formed of lithium lanthanum zirconium oxide (LLZO) or lithium lanthanum zirconium oxide doped with at least one metal element; In this case, the cross section of each of the LLZO large particles in the corresponding LCO large particle has a high central portion and an arc-shaped protrusion shape with flat ends on both sides, and a first LLZO dielectric layer is formed between each bottom of the LLZO large particle and the LCO large particle to guide lithium ions and protect the LCO large particle; The cross section of each of the LLZO small particles in the LCO large particle is high in the center and has an arc-shaped protrusion shape with flat both ends, and a second LLZO dielectric layer is formed between the bottom of each of the LLZO small particles and the LCO large particle; The ion guiding ability of the plurality of LLZO large particles and the plurality of LLZO small particles for lithium ions is higher than that of the LCO large particles, and side reactions with lithium ions are unlikely to occur. When lithium ions pass through the positive electrode, they are guided by the plurality of LLZO large particles and the plurality of LLZO small particles that are dispersed, and the paths of lithium ions are dispersed. The LCO positive electrode particles coated with oxide and carbon nanotubes are characterized in that each of the LLZO large particles, each of the LLZO small particles, and the LCO large particles all have a crystalline structure, have good stability, are difficult to release or dissociate, and increase the voltage of the entire battery.

2. 2. The LCO positive electrode particles coated with oxide and carbon nanotubes according to claim 1, wherein the size of the large LCO particles is in the range of 10 μm to 15 μm, the lateral size of each of the large LLZO particles is in the range of 100 nm to 280 nm, and the lateral size of each of the small LLZO particles is in the range of 50 nm to 100 nm, the lateral size being the size along the spherical direction of the corresponding large LCO particle, the thickness of the intermediate layer of the first LLZO dielectric layer is in the range of 2 nm to 12 nm, and the thickness of the intermediate layer of the second LLZO dielectric layer is in the range of 2 nm to 12 nm.

3. 2. The LCO positive electrode particles coated with oxide and carbon nanotubes according to claim 1, wherein the weight ratio of the plurality of large LLZO particles to the large LCO particles is in the range of 0.5 wt% to 0.8 wt%, and the weight ratio of the plurality of small LLZO particles to the large LCO particles is in the range of 0.1 wt% to 0.3 wt%.

4. The first LLZO dielectric layer and the second LLZO dielectric layer are mainly composed of lithium lanthanum zirconium oxide (Li 7 La 3 Zr 2 O 12 2. The LCO positive electrode particle coated with oxide and carbon nanotubes according to claim 1, characterized in that the LCO positive electrode particle is formed of lithium lanthanum zirconium oxide doped with cobalt oxide or at least one metal element, and cobalt oxide or a cobalt derivative, and is used to provide lithium ions with preferred guide channels, the cobalt being mainly obtained from the outer layer of the LCO large particle.

5. The second LLZO dielectric layer includes a second interface oxygen-deficient layer and a second derivative layer that are generated during the sintering process. The second interface oxygen-deficient layer is made of lanthanum zirconate (La). 2 Zr 2 O 7 ) and lanthanum oxide (La 2 O 3 ) as a component of the second derivative layer, and lithium phosphate (Li 3 PO 4 2. The LCO cathode particles coated with oxide and carbon nanotubes according to claim 1, wherein the second derivative layer has the ability to conduct lithium ions, the second interfacial oxygen-deficient layer is used as an ion-conducting connecting layer for protection, and the second derivative layer is derived from the surface of the LCO large particles, the surface of the LLZO large particles, and the surface of the LLZO small particles to form a thin film.

6. The LCO positive electrode particle coated with oxide and carbon nanotubes according to claim 1, characterized in that the composite LCO particle further comprises a plurality of carbon nanotubes of different sizes around the outer periphery thereof, the plurality of carbon nanotubes covering the entire composite LCO particle.

7. the plurality of carbon nanotubes comprises a plurality of short-chain carbon nanotubes and a plurality of long-chain carbon nanotubes, each of the short-chain carbon nanotubes having a length in the range of 0.5 μm to 3 μm, and each of the long-chain carbon nanotubes having a length in the range of 8 μm to 12 μm; 7. The LCO positive electrode particle coated with oxide and carbon nanotubes according to claim 6, wherein each of the short-chain carbon nanotubes is used to straddle each of the LLZO large particles and each of the LCO large particles, and to straddle each of the LLZO small particles and each of the LCO large particles, and a plurality of the long-chain carbon nanotubes is used to coat a plurality of the short-chain carbon nanotubes and the composite LCO particles.

8. 8. The LCO cathode particles coated with oxide and carbon nanotubes according to claim 7, wherein the weight ratio of the plurality of carbon nanotubes to the LCO large particles is in the range of 0.01 wt% to 0.5 wt%, and the weight ratio of the plurality of short-chain carbon nanotubes to the plurality of long-chain carbon nanotubes is 5:

2.

9. 2. The oxide-carbon nanotube-coated LCO cathode particles according to claim 1, wherein each of the large LLZO particles and each of the small LLZO particles are composed of at least one of 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).

10. Each of the large LLZO particles and each of the small LLZO particles are Cu a ,X b -LLZO, and a ,X b -LLZO is lithium lanthanum zirconium oxide doped with copper and element X, where X is selected from Ga (gallium), Ta (tantalum), Sr (strontium), Ba (barium), and Al (aluminum), and a>0 and b>0; a ,X b 2. The oxide and carbon nanotube-coated LCO cathode particles according to claim 1, wherein -LLZO is used to further stabilize the overall structure of the composite LCO particles, make the lithium ion channels smoother, accelerate the sintering rate in an oxygen atmosphere, and reduce the formation of lithium carbonate when exposed to air.

11. Cu a ,X b The LCO positive electrode particles coated with oxide and carbon nanotubes according to claim 10, characterized in that in -LLZO, a+b=0.25-0.8, a>0.1.

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