Method for preparing LCO cathode material coated with oxide and carbon nanotube

Abstract

To provide a method for producing an LCO positive electrode material coated with an oxide and carbon nanotubes.SOLUTION: A method for manufacturing a cathode material coated with an oxide and carbon nanotubes includes the following steps: mixing a LLZO material and a plurality of LLCO large particles to form a plurality of composite LLCO particles, wherein the LLZO material includes a plurality of LLZO large particles and a plurality of LLZO small particles; sintering the composite LLCO particles in an oxygen atmosphere to obtain a sintered powder, wherein a first LLZO dielectric layer is formed between a bottom of each of the LLZO large particles and a corresponding one of the LLCO large particles, and a second LLZO dielectric layer is formed between a bottom of each of the LLZO small particles and a corresponding one of the LLCO large particles; and introducing the sintered powder and the plurality of carbon nanotubes into a mixer to mix and stir to form a plurality of composite LLCO particles coated with the carbon nanotubes on an outer surface thereof.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a battery cathode material, and more particularly to a method for producing an LCO cathode material 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 was made through intensive research by the inventors in view of the above problems, and its purpose is to provide a method for producing an LCO cathode material 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 provides a method for preparing an LCO cathode material coated with oxides and carbon nanotubes. The surface of large LCO particles is coated with large and small LLZO particles and a dielectric layer to form composite LCO particles, enhancing ionic conductivity and protection. Because electron transport and ion transport are interdependent, the present invention addresses the problem of partial reduction in electronic conductivity due to the ceramic nature of the oxide. To address this issue, the outer surface of the composite LCO particles is coated 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 large and small LLZO particles and between the composite LCO particles and other materials in the cathode substrate, forming a small electron transport system that facilitates ion transport and improves electron and ion transport throughout the cathode. The coating effect of the carbon nanotubes and large and small LLZO 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. [Brief explanation of the drawings]

[0007] [Figure 1]1 is a flowchart illustrating a method for fabricating an LCO cathode material coated with oxide and carbon nanotubes according to one embodiment of the present invention. [Figure 2] 1 is a schematic diagram showing an embodiment of the present invention; [Figure 3] 1 illustrates one embodiment of a method for producing an oxide and carbon nanotube coated LCO cathode material according to the present invention. [Figure 4] 1 is a schematic enlarged view showing a configuration according to an embodiment of the present invention. [Figure 5] FIG. 10 is a schematic enlarged view showing a configuration according to another embodiment of the present invention. [Figure 6] 1 is a schematic diagram showing a coating of a short-chain carbon nanotube according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0008] The following describes in detail the embodiments of the present invention, but the present invention is not limited to these, and various modifications are possible within the scope of the description, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0009] Hereinafter, the method for manufacturing an LCO cathode material coated with oxide and carbon nanotubes according to the present invention will be described in detail with reference to FIGS.

[0010] The method for producing an oxide- and carbon nanotube-coated LCO cathode material according to the present invention includes the steps of: forming a cathode material having a plurality of cathode particles 200 in a cathode 100; and forming the oxide into a lithium lanthanum zirconium oxide (Li7La3Zr2O 12) or lithium lanthanum zirconium oxide doped with at least one metal element. The plurality of positive electrode particles 200 are used in the positive electrode of a solid-state battery or a battery of the like. The positive electrode 100 mainly includes a positive electrode substrate 10 (see FIG. 3) 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 the plurality of positive electrode particles 200. 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.

[0011] As shown in FIG. 1, the method of the present invention is used to manufacture a plurality of the cathode particles 200 and includes the following steps. <Process 500> The LLZO material is mixed with a plurality of LCO (LiCoO2, lithium cobalt oxide) large particles 22. The size of each of the LCO large particles 22 ranges between 10 μm and 15 μm, and the LCO large particles 22 are cubic with an irregular shape. The LLZO material includes a plurality of LLZO large particles 24 and a plurality of LLZO small particles 26, and the size of the LLZO large particles 24 is larger than that of the LLZO small particles 26. The LLZO material is lithium lanthanum zirconium oxide (Li7La3Zr2O 12 ) or lithium lanthanum zirconium oxide doped with at least one metal element.

[0012] The plurality of LLZO small particles 26 and the plurality of LLZO large particles 24 are thoroughly mixed with the plurality of LCO large particles 22 by a mixer 50 to uniformly mix the three. The mixer 50 is a three-dimensional mixer or a roll mixer.

[0013] In the mixing process, first, a plurality of the LLZO large particles 24 and a plurality of the LCO large particles 22 are added and stirred for half the total mixing time of the mixer 50 (step 500-1), and then a plurality of the LLZO small particles 26 are added and continuously stirred until the total mixing time of the mixer 50 is completed (step 500-2). The mixing speed of the mixer 50 is in the range of 50 to 100 rpm, and the total mixing time is in the range of 8 to 12 hours. After mixing, the outer surface of each of the LCO large particles 22 is coated with many of the corresponding LLZO large particles 24 and LLZO small particles 26, forming corresponding composite LCO particles 20. The lateral size of each of the LLZO large particles 24 (i.e., the size in the direction along the spherical surface of the corresponding LCO large particle 22) is in the range of 100 nm to 200 nm, and the lateral size of each of the LLZO small particles 26 (i.e., the size in the direction along the spherical surface of the corresponding LCO large particle 22) is less than 50 nm.

[0014] In each of the composite LCO particles 20, the weight ratio of the corresponding plurality of LLZO large particles 24 to the corresponding LCO large particle 22 of the LCO large particle 22 ranges between 0.5% and 0.8%, and the weight ratio of the corresponding plurality of LLZO small particles 26 to the corresponding LCO large particle 22 ranges between 0.1% and 0.3%.

[0015] The LLZO large particles 24 cannot adequately cover each of the LCO large particles 22, resulting in many gaps. Therefore, the gaps between the LLZO large particles 24 are filled with the corresponding LLZO small particles 26. This mixing method achieves stable process and surface coverage.

[0016] <Process 510> Next, the plurality of composite LCO particles 20 are sintered in an oxygen atmosphere at a sintering temperature ranging from 300°C to 450°C, a heating rate ranging from 3°C to 5°C / min, and the maximum temperature is maintained for 1 to 2 hours to obtain a sintered powder 40, i.e., a plurality of the positive electrode particles 200. Essentially, when sintered in the oxygen atmosphere, each of the LLZO large particles 24 and each of the LLZO small particles 26 shortens its longitudinal size (i.e., the direction perpendicular to the lateral direction) and widens its lateral size, but the total volume remains unchanged.

[0017] After sintering in the oxygen atmosphere, the profile of each longitudinal cross section (i.e., a cross section perpendicular to the horizontal direction) of the LLZO large grains 24 in the corresponding LCO large grains 22 exhibits an arc-shaped protrusion with a high center and flat ends (see FIG. 4). A first LLZO dielectric layer 25 is formed between the bottom of each LLZO large grain 24 and the corresponding LCO large grain 22. The first LLZO dielectric layer 25 is mainly composed of LLZO material, cobalt (Co) oxide, and a cobalt derivative (the cobalt is mainly obtained from the outer layer of the LCO large grains 22). Its function is to provide lithium ions with favorable guide channels. The thickness of the intermediate layer of the first LLZO dielectric layer 25 is in the range of 2 to 12 nm.

[0018] 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, respectively, during sintering in the oxygen atmosphere. The first interface oxygen-deficient layer 251 contains lanthanum zirconate (La2Zr2O7) and lanthanum oxide (La2O3). The first derivative layer 252 contains lithium phosphate (Li3PO4). The thickness of both layers ranges from 1 nm to 10 nm. The first LLZO dielectric layer 25 helps connect the corresponding LCO large grains 22 and the corresponding LLZO large grains 24, forming a continuous interface. The first derivative layer 252 itself also has the ability to conduct lithium (Li) ions, although its ability is slightly inferior to that of the LLZO large grains 24. The first interface oxygen-deficient layer 251 serves as a connection layer for ion conduction and for protection. The first derivative layer 252 is derived from the surfaces of the corresponding LCO large particles 22, the surfaces of the LLZO large particles 24, and the surfaces of the LLZO small particles 26, forming a thin film.

[0019] 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 corresponding LCO large particle 22 is arc-shaped with a high center and flat ends (see FIG. 5). A second LLZO dielectric layer 27 is formed between the bottom of each of the LLZO small particles 26 and the corresponding LCO large particle 22. The second LLZO dielectric layer 27 is mainly composed of LLZO, cobalt (Co), and an oxide of a cobalt derivative (the cobalt is mainly obtained from the outer layer of the LCO large particle 22). Its function is to provide lithium ions with favorable guide channels. The thickness of the intermediate layer of the second LLZO dielectric layer 27 is in the range of 2 to 12 nm.

[0020] The second LLZO dielectric layer 27 includes a second interface oxygen-deficient layer 271 and a second derivative layer 272, which are generated by the LLZO small particles 26 and the LCO large particles 22 during sintering in the oxygen atmosphere. The second interface oxygen-deficient layer 271 contains lanthanum zirconate (La2Zr2O7) and lanthanum oxide (La2O3). The second derivative layer 272 contains lithium phosphate (Li3PO4). The thickness of both layers ranges from 1 nm to 10 nm. The second LLZO dielectric layer 27 facilitates connection between the LCO large particles 22 and the LLZO small particles 26, creating a continuous interface. The second derivative layer 272 itself also has the ability to conduct lithium ions, but its ability is somewhat inferior to that of the LLZO small particles 26. Therefore, the second interface oxygen-deficient layer 271 serves as an ion-conducting connection layer and is used for protection. The second derivative layer 252 is derived on the surfaces of the corresponding LCO large particles 22, the surfaces of the LLZO large particles 24, and the surfaces of the LLZO small particles 26 to form a thin film.

[0021] The first dielectric layer 25 and the second dielectric layer 27 form an LCO layer connected to the LLZO material. The first dielectric layer 25 and the second dielectric layer 27 contain La2Zr2O7 and partial La2O3. The more completely the LLZO large particles 24 and the LLZO small particles 26 are coated on the corresponding LCO large particles 22, 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 a more stable cathode material. The La2Zr2O7 itself also has lithium ion conductivity. While its conductivity is inferior to that of the LLZO material, it acts as an ion-conducting layer to help conduct lithium ions from the LCO to the LLZO material. The LLZO material acts as a high-speed tunnel for conducting lithium ions. After reaching the LLZO material via the first dielectric layer 25 and the second dielectric layer 27, the LCO lithium ions can efficiently enter and exit the LLZO material at high speed. Furthermore, the La2Zr2O7 itself has the inertness of a ceramic compound, which can reduce side reactions between the positive electrode and the electrolyte. Particularly in the case of high voltages (over 4.5V to 4.9V), the first dielectric layer 25 and the second dielectric layer 27 can provide the effect of slowing down and protecting LCO.

[0022] <Process 520> The sintered powder 40 and a plurality of carbon nanotubes (CNTs) 30 are mixed and stirred in a stirrer 55. The stirring rotation speed of the stirrer 55 is in the range of 50 to 150 rpm, and the stirring time is in the range of 3 to 6 hours. The stirrer 55 is a planetary stirrer or a roller stirrer.

[0023] The agitator 55 according to the present invention can be divided into two types: a wet type agitator (such as a planetary agitator) and a dry type agitator (such as a three-dimensional mixer). The wet type agitator has a good effect, but it needs to be dried to remove moisture.

[0024] The plurality of carbon nanotubes 30 according to the present invention comprises a plurality of short-chain carbon nanotubes 32 and a plurality of long-chain carbon nanotubes 34. The length of each of the short-chain carbon nanotubes 32 is in the range of 0.5 μm to 3 μm, and the length of each of the long-chain carbon nanotubes 34 is in the range of 8 μm to 12 μm. The weight ratio of the plurality of short-chain carbon nanotubes 32 to the plurality of long-chain carbon nanotubes 34 is 5:2, and the weight ratio of the plurality of carbon nanotubes 30 to the plurality of LCO large particles 22 is in the range of 0.01% to 0.5%.

[0025] After the stirring in step 520, a plurality of the composite LCO particles 20 are formed whose outer surfaces are coated with a plurality of the carbon nanotubes 30, and the plurality of the carbon nanotubes 30 are randomly distributed on the surface of each of the composite LCO particles 20. After the above-mentioned steps 500 to 520, the size of each of the large LCO particles 22 is in the range of 10 μm to 15 μm, the lateral size of each of the large LLZO particles 24 is in the range of 100 nm to 280 nm, and the lateral size of the small LLZO particles 26 is in the range of 50 nm to 100 nm.

[0026] The carbon nanotubes 30 of different lengths form different spanning distances in each of the composite LCO particles 20. Each of the short-chain carbon nanotubes 32 can span between the corresponding large LLZO particle 24 and the corresponding large LCO particle 22, and between the corresponding small LLZO particle and the corresponding large LCO particle 22. The long-chain carbon nanotubes 34 coat the entire composite LCO particle 20 and are used to enhance the overall structural strength. The carbon nanotubes 30 are highly conductive and form a hairball-like morphology when attached to the composite LCO particle 20 (see FIG. 2).

[0027] The carbon nanotubes 30 are used to increase electrical conductance, i.e., conductive bridges are formed around the LLZO large particles 24 and the LLZO small particles 26, respectively, allowing electrons to be conducted between the composite LCO particles 20. The carbon nanotubes 30 have extremely high electrical conductivity, allowing lithium ions to be conducted between the different LLZO large particles 24, the LLZO small particles 26, and the LCO large particles 22. This improves the overall electrical conductivity of the cathode 100.

[0028] Preferably, the LLZO material is LLZO(Li7La3Zr2O 12 At least one type is selected from the group consisting 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).

[0029] Preferably, the LLZO material is Cu a ,X bThe LLZO material is lithium lanthanum zirconium oxide (LLZO), i.e., lithium lanthanum zirconium oxide doped with copper and element X. X is selected from Ga (gallium), Ta (tantalum), Sr (strontium), Ba (barium), and Al (aluminum), and a > 0 and b > 0. Preferably, a + b is in the range of 0.25 to 0.8, and a > 0.1. Although doping copper into LLZO is very difficult, it makes the overall structure of the composite LCO particles 20 more stable, smoother lithium ion channels, and accelerates the sintering rate in an oxygen atmosphere, further reducing manufacturing costs. Furthermore, the formation of lithium carbonate (Li2CO3) when the LLZO material is exposed to air is reduced, i.e., the surface stability of the entire material is improved during sintering.

[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 embodiments. It is clear 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 1st 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 40 Sintered Powder 50 Mixer 55 Mixer 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. 1. A method for producing an LCO cathode material coated with an oxide and carbon nanotubes, wherein the cathode material in a cathode is a plurality of cathode particles, the oxide is an LLZO material, and the plurality of cathode particles are used in a cathode of a solid-state or solid-state battery, the method comprising: The LLZO material and multiple LCO (LiCoO) particles are then mixed to form multiple composite LCO particles. 2 The LLZO material includes a plurality of LLZO large particles and a plurality of LLZO small particles, and the LLZO material is 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 step B: sintering a plurality of the composite LCO particles in an oxygen atmosphere to obtain a sintered powder, which is a plurality of the positive electrode particles; and a second LLZO dielectric layer is formed between the bottom of each of the LLZO small particles and the corresponding LCO large particle, the cross section of which is higher in the center and flattened at both ends. The method for producing an LCO positive electrode material coated with oxide and carbon nanotubes is characterized in that, when sintering is performed in the oxygen atmosphere, each of the LLZO large particles in the corresponding LCO large particle has a cross section that is higher in the center and flattened at both ends, a first LLZO dielectric layer is formed between the bottom of each of the LLZO large particles and the corresponding LCO large particle, the first LLZO dielectric layer being composed of the LLZO material, cobalt oxide, and a cobalt derivative, with the cobalt being mainly obtained from the outer layer of the LCO large particle. The method for producing an LCO positive electrode material coated with oxide and carbon nanotubes is characterized in that, when sintering is performed in the oxygen atmosphere, each of the LLZO large particles in the corresponding LCO large particle has a cross section that is higher in the center and flattened at both ends, a first LLZO dielectric layer is formed between the bottom of each of the LLZO small particles and the corresponding LCO large particle, the second LLZO dielectric layer being composed mainly of the LLZO material, cobalt oxide, and a cobalt derivative.

2. 2. The method for preparing an LCO cathode material coated with oxide and carbon nanotubes according to claim 1, wherein in step A, the plurality of small LLZO particles, the plurality of large LLZO particles, and the large LCO particles are thoroughly stirred by a mixer to uniformly mix the three to form the plurality of composite LCO particles.

3. and (C) mixing and stirring the sintered powder and a plurality of carbon nanotubes (CNTs) in a stirrer to form a plurality of composite LCO particles whose outer surfaces are coated with the plurality of carbon nanotubes, the plurality of carbon nanotubes being randomly distributed on the surface of each of the composite LCO particles; 3. The method for producing an LCO positive electrode material coated with oxide and carbon nanotubes according to claim 1, wherein the carbon nanotubes of different lengths in the composite LCO particles form different spanning distances, and the carbon nanotubes are straddled between each of the LLZO particles and the corresponding large LCO particles, and between each of the LLZO small particles and the corresponding large LCO particles, and coat each of the composite LCO particles to enhance their structural strength.

4. In step B, before sintering in the oxygen atmosphere, the lateral size of each of the LLZO large particles is in the range of 100 nm to 200 nm, and the lateral size of each of the LLZO small particles is less than 50 nm, and the lateral size is the size along the spherical direction of the corresponding LCO large particle; the thickness of the first LLZO dielectric layer and the intermediate layer of the second LLZO dielectric layer after sintering in the oxygen atmosphere is in the range of 2 to 12 nm; 4. The method for producing an LCO cathode material coated with oxide and carbon nanotubes according to claim 3, wherein after step C, the size of each 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.

5. 4. The method for producing an LCO cathode material coated with oxide and carbon nanotubes according to claim 3, wherein, in each of the composite LCO particles, the weight ratio of the corresponding plurality of LLZO large particles of the large LCO particle to the corresponding LCO large particle is in the range of 0.5% to 0.8%, and the weight ratio of the corresponding plurality of LLZO small particles of the large LCO particle to the corresponding LCO large particle is in the range of 0.1% to 0.3%.

6. 4. The method for preparing an LCO cathode material coated with oxide and carbon nanotubes according to claim 3, wherein the mixer is a three-dimensional mixer or a roll mixer, and in step A, the large LLZO particles and the large LCO particles are first added and stirred for half of the total stirring time of the mixer, and then the small LLZO particles are added to complete the total stirring time of the mixer, the stirring rotation speed of the mixer is in the range of 50 to 100 rpm, and the total stirring time is in the range of 8 to 12 hours, and after stirring, the outer surface of each large LCO particle is coated with a corresponding number of large LLZO particles and small LLZO particles to form corresponding composite LCO particles.

7. In step B, the sintering temperature is in the range of 300 to 450°C, the heating rate is 3 to 5°C / min, and the maximum temperature is maintained for 1 to 2 hours to obtain the sintered powder. When the LLZO large particles and the LLZO small particles are sintered in the oxygen atmosphere, their vertical size becomes shorter and their horizontal size becomes wider, but their total volume does not change, and the vertical size is the size perpendicular to the horizontal direction.

4. The method for preparing an LCO cathode material coated with oxide and carbon nanotubes according to claim 3, wherein in step C, the agitator is a planetary agitator or a roller agitator, the agitation rotation speed of the agitator is in the range of 50 to 150 rpm, and the agitation time is in the range of 3 to 6 hours.

8. The first LLZO dielectric layer includes a first interface oxygen-deficient layer and a first derivative layer that are generated by each of the LLZO large grains and each of the LCO large grains during sintering in the oxygen atmosphere, and the first interface oxygen-deficient layer contains lanthanum zirconate (La) as a component. 2 Zr 2 O 7 ) and lanthanum oxide (La 2 O 3 ) as a component of the first derivative layer, and lithium phosphate (Li 3 PO 4 ), both of which have a thickness ranging between 1 nm and 10 nm, and the first LLZO dielectric layer helps to connect each of the LCO large grains and each of the LLZO large grains to form a continuous interface; The second LLZO dielectric layer includes a second interface oxygen-deficient layer and a second derivative layer that are generated by each of the LLZO small particles and each of the LCO large particles during sintering in the oxygen atmosphere, and the second interface oxygen-deficient layer contains lanthanum zirconate (La) as a component. 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 ), both of which have a thickness ranging between 1 nm and 10 nm, and the second LLZO dielectric layer helps to connect each of the large LCO particles and each of the small LLZO particles to form a continuous interface; 2. The method for fabricating an oxide and carbon nanotube coated LCO cathode material according to claim 1, wherein the first and second derivative layers have lithium ion conducting ability, and the first and second interfacial oxygen-deficient layers are used as ion-conducting connecting layers and for protection.

9. 4. The method for manufacturing an LCO cathode material coated with oxide and carbon nanotubes according to claim 3, wherein the carbon nanotubes comprise a plurality of short-chain carbon nanotubes and a plurality of long-chain carbon nanotubes, each of the short-chain carbon nanotubes being used to straddle a corresponding one of the large LLZO particles and a corresponding one of the large LCO particles, and a corresponding one of the small LLZO particles and a corresponding one of the large LCO particles, and the plurality of long-chain carbon nanotubes being used to coat each of the composite LCO particles to enhance the overall structural strength, wherein the length of each of the short-chain carbon nanotubes is in the range of 0.5 μm to 3 μm, and the length of each of the long-chain carbon nanotubes is in the range of 8 μm to 12 μm.

10. 10. The method for manufacturing an LCO cathode material coated with oxide and carbon nanotubes, as described in claim 9, wherein the weight ratio of the plurality of carbon nanotubes to the plurality of LCO large particles is in the range of 0.01% to 0.5%, and the weight ratio of the plurality of short-chain carbon nanotubes to the plurality of long-chain carbon nanotubes in the plurality of carbon nanotubes is 5:

2.

11. The LLZO material is LLZO(Li 7 La 3 Zr 2 O 12 2. The method for producing an LCO cathode material coated with oxide and carbon nanotubes according to claim 1, wherein at least one of the oxides is selected from the group consisting 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).

12. The LLZO material is Cu a ,X b 2. The method for preparing an LCO cathode material coated with oxide and carbon nanotubes according to claim 1, wherein the LCO cathode material is lithium lanthanum zirconium oxide-LLZO, i.e., 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 where a>0 and b>0, to further stabilize the overall structure of the composite LCO particles, make the lithium ion channels smoother, increase the sintering rate in an oxygen atmosphere, and reduce the formation of lithium carbonate when exposed to air.

13. Cu a ,X b 13. The method for preparing an LCO cathode material coated with oxide and carbon nanotubes according to claim 12, wherein in LLZO, a+b=0.25-0.8, a>0.1.

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