NCM positive electrode particles coated with LLZO and glass phase

Abstract

To provide NCM positive electrode particles coated with LLZO and a glass phase.SOLUTION: NCM (lithium nickel manganese cobalt oxide) large particles, wherein the NCM large particles have a glass phase on the outside of the NCM large particles, the glass phase is used to prevent the NCM large particles from directly contacting the electrolyte, and the glass phase is used to reduce interfacial side reactions, and at the same time, the glass phase reduces the interfacial resistance when lithium ions enter and leave the NCM large particles, and a plurality of LLZO fine particles distributed in the glass phase or on the surface of the glass phase to form a composite NCM particle as a whole. The periphery of the composite NCM particles is covered with a plurality of carbon nanotubes, and positive electrode particles covering the carbon nanotubes are formed. The plurality of nano-scale amorphous carbon is coated on the outside of the positive electrode particles coated with the carbon nanotubes, and is located in gaps formed by the plurality of carbon nanotubes crossing each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to positive electrode particles, and more particularly to NCM positive electrode particles coated with LLZO and glass phases. [Background technology]

[0002] A battery is primarily composed of a positive electrode and a negative electrode disposed in an electrolyte. The positive electrode is made by mixing and stirring many positive electrode conductive units (positive electrode materials such as lithium cobalt oxide) and dispersing them in a slurry. Typically, the positive electrode conductive units are first mixed and stirred with the conductive slurry before being applied to an electrode sheet and assembled into a battery. Since the positive electrode conductive units are connected to each other via the conductive slurry, the conductive slurry has conductive properties, which allow free electrons to migrate between different positive electrode conductive units and eliminate the need for excessive energy consumption due to internal resistance, thereby achieving the goal of efficient conductivity. Therefore, to adjust the conductivity of the slurry, it is necessary to manufacture the slurry using specific conductive materials. Summary of the Invention [Problem to be solved by the invention]

[0003] To improve electrical conductivity, the cathode slurry is filled with a plurality of cathode particles, the material of which is selected from lithium nickel manganese cobalt oxide (NCM), lithium manganese iron phosphate (LMFP), or a mixture thereof, and the cathode particles are dispersed in the cathode slurry. However, conventional cathode particles are prone to side reactions at their interfaces, shortening the service life of the cathode and reducing the overall efficiency of the battery due to their low electronic conductivity.

[0004] The present invention was made through intensive research by the inventors in view of the above problems, and its object is to provide NCM positive electrode particles coated with LLZO and a glass phase. [Means for solving the problem]

[0005] To address the above-mentioned problems, one embodiment of the present invention provides NCM positive electrode particles coated with LLZO and a glass phase. The outer surfaces of the NCM large particles are coated with a glass phase, which prevents the NCM large particles from directly contacting the electrolyte, suppressing interfacial side reactions and reducing the interfacial resistance when lithium ions enter and exit the NCM large particles. This improves the charge-discharge performance, accommodates volume changes during charge and discharge, improves the mechanical properties of the powder, and reduces fracture. The present invention coats the NCM large particles with a plurality of LLZO fine particles, which have the ability to accommodate and uniformly guide lithium ions. As lithium ions pass through the positive electrode, the LLZO fine particles guide them and disperse the lithium ion pathways, providing more suitable pathways for the lithium ions. In the present invention, the outer surface of the NCM large particle that covers the LLZO fine particles is further coated with multiple carbon nanotubes and nanoscale amorphous carbon, allowing electrons to be conducted through the composite NCM particle, and the nanoscale amorphous carbon is filled between the multiple carbon nanotubes to form a complete electron conduction path, thereby providing stability to the entire cathode structure and reducing the amount of cobalt used.

[0006] At least the following points will become clear from the description and drawings to be described later. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram showing a configuration of a positive electrode particle according to an embodiment of the present invention. [Figure 2] FIG. 1 is a structural diagram showing a positive electrode according to an embodiment of the present invention. [Figure 3] 1 is a structural diagram showing a composite NCM particle according to an embodiment of the present invention. [Figure 4] It is a configuration diagram showing composite NCM particles and short-chain carbon nanotubes according to an embodiment of the present invention. [Figure 5] It is a configuration diagram showing a positive electrode particle coated with a carbon nanotube according to an embodiment of the present invention.

Mode for Carrying Out the Invention

[0008] Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the invention according to the claims. Also, not all combinations of features described in the embodiments are essential for the solution of the invention.

[0009] First, an example of a specific embodiment of NCM positive electrode particles coated with LLZO and a glass phase of the present invention will be described while referring to FIGS. 1 to 5.

[0010] The NCM positive electrode particles coated with LLZO and a glass phase according to an embodiment of the present invention are such that the NCM positive electrode particles coated with LLZO and a glass phase are mainly used for the positive electrode 100 of general solid or solid batteries (see FIG. 2). The positive electrode 100 includes a positive electrode substrate 10 and a positive electrode slurry layer 12 applied to 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 80 wt% to 98 wt% of the weight of the positive electrode slurry layer 12.

[0011] The NCM positive electrode particles coated with LLZO and a glass phase according to the present invention are each of the positive electrode particles 200 and mainly have the following configuration.

[0012] <NCM (lithium nickel manganese cobalt oxide) large particles 22> The NCM large particles 22 have a size ranging from 3 μm to 5 μm and have a single crystal structure. As shown in Figure 1, the NCM large particles 22 have an irregular cubic shape. NCM is a ternary oxide.

[0013] The outer surfaces of the NCM large particles 22 are covered with a glass phase 25, and the glass phase 25 covers part or all of the outer surfaces of the NCM large particles (preferably the entire surface). As shown in Figure 3, an NCM particle 250 is formed that has a glass phase throughout. The glass phase 25 has a lithium ion conductivity of 10 -5 The glass phase 25 is composed of an amorphous oxide or non-oxide solid electrolyte having a glassy phase of lithium and an oxide of a group IIIA, IVA, or VA element (e.g., LiO-RO x where R is at least one element of boron (B), aluminum (Al), silicon (Si), germanium (Ge), phosphorus (P), or arsenic (As), and x=1 to 3; lithium halide or lithium halogen-oxide (e.g., Li-MO, where M is at least one element of the halogen elements fluorine (F), chlorine (Cl), bromine (Br), or iodine (I)); lithium sulfide (e.g., Li2S-P2S5); amorphous oxide-based solid electrolyte (e.g., amorphous perovskite-based solid electrolyte (Li-La-Ti-O, LLTO)); garnet-based solid electrolyte (Li-La-Zr-O, LLZO); or lithium phosphorus oxynitride (LiPON).

[0014] The thickness of the glass phase 25 ranges between 5 nm and 100 nm.

[0015] The glass phase 25 can prevent the NCM large particles 22 from directly contacting the electrolyte, suppressing side reactions at the interface and simultaneously reducing the interface resistance when lithium ions enter and exit the NCM large particles 22, thereby improving the charge-discharge performance. The glass phase 25 can accommodate the volume that changes during charge and discharge, improving the mechanical properties of the powder and reducing fracture.

[0016] A plurality of LLZO particles 24 are distributed within the glass phase 25 or on the surface of the glass phase 25, and a composite NCM particle 20 is formed by the NCM large particle 22, the glass phase 25, and the plurality of LLZO particles 24. The size of the NCM large particle 22 is larger than the size of each of the LLZO particles 24. Each of the LLZO particles 24 is 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 The LLZO particles 24 may be gallium (Ga)-doped lithium lanthanum zirconium oxide, or aluminum (Al)-doped or barium (Ba)-doped lithium lanthanum zirconium oxide. The lateral size of each of the LLZO particles 24 (i.e., the size along the spherical surface of the corresponding NCM large particle 22) ranges from 50 nm to 300 nm. The LLZO particles 24 are distributed in the glass phase 25 by sintering, and after sintering, each of the LLZO particles 24 shortens its longitudinal size (i.e., the size perpendicular to the lateral direction) and widens its lateral size, while the total volume remains unchanged. In the composite NCM particle 20, the total weight of the LLZO particles 24 and the weight ratio of the NCM particles 250 having the glass phase ranges from 0.2% to 2%.

[0017] In the present invention, a plurality of LLZO particles 24 are attached to the inside and outside of the glass phase 25 on the outer surface of the NCM large particles 22, and the ion guiding ability of the LLZO particles 24 for lithium ions is much higher than that of the NCM large particles 22, and no side reactions occur with the lithium ions. Therefore, when lithium ions pass through the positive electrode 100, these dispersed LLZO particles 24 guide them, thereby dispersing the paths of the lithium ions. In this way, the present invention provides more suitable paths for lithium ions, greatly improving the overall efficiency of the battery, and by preventing side reactions from occurring, the service life of the entire battery can be extended.

[0018] Preferably, each of the LLZO particles 24 is composed of at least one element selected from 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).

[0019] Preferably, each of the LLZO particles 24 is Cu a ,X b -LLZO, and a ,X bLLZO is a lithium lanthanum zirconium oxide doped with copper and an element X, where X is selected from gallium (Ga), tantalum (Ta), strontium (Sr), barium (Ba), and aluminum (Al), and a > 0 and b > 0. Preferably, a + b = 0.25 to 0.8, and a > 0.1. Although the technique of doping LLZO with copper is very difficult, it further stabilizes the overall structure, smooths the lithium ion channels, increases the sintering rate, and reduces manufacturing costs. Furthermore, exposing the LLZO particles 24 to air reduces the formation of lithium carbonate (Li2CO3), improving the surface stability of the entire material during sintering.

[0020] The LLZO fine particles 24 and the NCM large particles 22 both 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.

[0021] 4 and 5, the present invention further includes a plurality of carbon nanotubes (CNTs) 30 that coat the outer periphery of the composite NCM particle 20. The plurality of carbon nanotubes 30 and the composite NCM particle 20 form a cathode particle 300 that coats the carbon nanotubes (see FIG. 5).

[0022] The carbon nanotubes 30 according to the present invention include 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 1 μm, and each of which has a length ranging from 3 μm to 8 μm. The total weight of the carbon nanotubes 30 and the weight ratio of the composite NCM particles 20 is in the range of 0.1% to 2%.

[0023] As shown in Figure 1, a plurality of the short-chain carbon nanotubes 32 are used to bridge the LLZO microparticles 24 and the NCM large particles 22 (see Figure 4). A plurality of the long-chain carbon nanotubes 34 are used to coat the composite NCM particles 20 (see Figure 1), so that the entire composite NCM particle 20 has good electrical conductivity. Carbon nanotubes are very good conductive materials and help conduct electrons throughout the cathode 100. Meanwhile, the LLZO microparticles 24 help conduct lithium ions.

[0024] The carbon nanotubes 30 are used to increase the electronic conductivity; that is, conductive bridges are formed between the different LLZO microparticles 24, allowing electrons to be conducted through the composite NCM particles 20. Carbon nanotubes have extremely high electrical conductivity, allowing electrons to be conducted between the different LLZO microparticles 24 and the NCM large particles 22 through the carbon nanotubes 30, thereby increasing the overall conductivity of the positive electrode 100. The carbon nanotubes 30 can form bridges with different numbers of layers on the LLZO microparticles 24 and the NCM large particles 22. The more carbon nanotubes 30 added, the higher the overall conductivity of the positive electrode 100.

[0025] The advantage of using carbon nanotubes in the present invention is that lithium ions are more easily stabilized between the carbon nanotubes, and the positive electrode slurry of the present invention contains a large number of solid lithium ions, thereby increasing the overall lithium ion conductivity. Furthermore, electrons are more easily fixed between the short-chain carbon nanotubes 32 and the long-chain carbon nanotubes 34, thereby increasing the overall lithium ion conductivity. Furthermore, the extremely high ion conductivity contributes to high-speed charging and discharging of the entire battery, and also reduces the amount of cobalt used, thereby reducing overall manufacturing costs.

[0026] A plurality of nanoscale amorphous carbons 35 coat the exterior of the carbon nanotube-coated positive electrode particles 300, and the nanoscale amorphous carbons 35 and the carbon nanotube-coated positive electrode particles 300 form a carbon material-coated positive electrode particle 350. Each of the nanoscale amorphous carbons 35 is mainly located in the gaps formed by the intersection of the carbon nanotubes 30. Preferably, the nanoscale amorphous carbon 35 is amorphous carbon of a super P conductive additive. The size of the nanoscale amorphous carbon 35 ranges from 20 nm to 100 nm. The total weight ratio of the nanoscale amorphous carbon 35 to the composite NCM particles 20 ranges from 0.1% to 2%. The nanoscale amorphous carbon 35 and the carbon nanotubes 30 both serve as conductive additives. Since the nanoscale amorphous carbon 35 is in the form of particles and the carbon nanotubes 30 are in the form of long thin pieces, gaps are formed between the carbon nanotubes 30 that intersect vertically and horizontally, and current cannot be conducted through these gaps. Therefore, in the present invention, by placing the nanoscale amorphous carbon 35 in the gaps, electric charges can be conducted between different carbon nanotubes 30 by bridging the nanoscale amorphous carbon 35, further increasing the current conduction efficiency.

[0027] The weight ratio of the total weight of the carbon nanotubes 30 and the nanoscale amorphous carbons 35 to the weight of the composite NCM particles 20 is (0.09-3):100.

[0028] The weight ratio of the plurality of carbon nanotubes 30, the plurality of nanoscale amorphous carbons 35, and the composite NCM particles 20 is 0.5:1:100.

[0029] By applying the above-described structure, the positive electrode 100 can accept more lithium ions, thereby enabling the positive electrode 100 to receive a higher voltage. For example, by applying the design of the present invention to a battery originally rated at 4.3 V, the voltage can be increased from 4.3 V to 4.5 V.

[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 NCM particles 22 NCM large particles 24 LLZO fine particles 25 Glass phase 30 Carbon nanotubes 32 Short-chain carbon nanotubes 34 Long-chain carbon nanotubes 35 Nanoscale amorphous carbon 100 positive electrode 200 positive particles 250 NCM particles with glass phase 300 Carbon nanotube coated cathode particles 350 Positive electrode particles coated on carbon material

Claims

1. NCM positive electrode particles coated with LLZO and a glass phase, the positive electrode particles being present in a positive electrode slurry layer of a positive electrode of a solid-state battery or a battery of solid-state batteries, the NCM positive electrode particles coated with LLZO and a glass phase comprising: The present invention provides an NCM (lithium nickel manganese cobalt oxide) large particle having an irregular cubic shape, the NCM large particle having a glass phase on its exterior, the glass phase covering part or all of the outer surface of the NCM large particle to form an NCM particle having a glass phase as a whole, the glass phase being used to prevent the NCM large particle from directly contacting an electrolyte and suppressing side reactions at the interface, and at the same time reducing the interface resistance when lithium ions enter and exit the NCM large particle; a plurality of LLZO particles, each of which is distributed within the glass phase or on the surface of the glass phase; a composite NCM particle is formed by the NCM large particle, the glass phase, and the plurality of LLZO particles; a size of the NCM large particle is larger than a size of each of the LLZO particles; and each of the LLZO particles is lithium lanthanum zirconium oxide (Li 7 La 3 Zr 2 O 12 and a plurality of LLZO particles formed of lithium lanthanum zirconium oxide (LLZO) or lithium lanthanum zirconium oxide doped with at least one metal element, The plurality of LLZO fine particles have a higher ion guiding ability for lithium ions than the NCM large particles, and do not cause side reactions with lithium ions. When lithium ions pass through the positive electrode, they are guided by the plurality of dispersed LLZO fine particles, and the lithium ion paths are dispersed. The LLZO particles are classified into 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), Al-LLZO (Al-doped LLZO, aluminum-doped lithium lanthanum zirconium oxide), and Cu a ,X b -LLZO, wherein the Cu a ,X b - LLZO is lithium lanthanum zirconium oxide doped with copper and element X, where X is selected from gallium (Ga), tantalum (Ta), strontium (Sr), barium (Ba), and aluminum (Al), and a>0 and b>0. NCM positive electrode particles are coated with LLZO and a glass phase.

2. The NCM positive electrode particles coated with LLZO and a glass phase according to claim 1, characterized in that the size of the NCM large particles is in the range of 3 μm to 5 μm, has a single crystal structure, and the thickness of the glass phase is in the range of 5 nm to 100 nm.

3. The glass phase has a lithium ion conductivity of 10 -5 2. The NCM positive electrode particle coated with LLZO and a glass phase according to claim 1, wherein the NCM positive electrode particle is composed of an amorphous oxide or non-oxide solid electrolyte having a resistivity of higher than 5000 kJ / cm, and the amorphous oxide or non-oxide solid electrolyte is one element selected from the group consisting of lithium halides, lithium halogen-oxides, oxides of lithium and group IIIA, IVA, and VA elements, amorphous oxide-based solid electrolytes, amorphous perovskite-based solid electrolytes, garnet-based solid electrolytes, lithium-phosphorus-oxygen-nitrides, and lithium-sulfides.

4. The glass phase has a lithium ion conductivity of 10 -5 2. The NCM positive electrode particles coated with LLZO and a glass phase according to claim 1, characterized in that the positive electrode particles are composed of an amorphous oxide or non-oxide solid electrolyte having a viscosity higher than 1000 kJ / cm, and the glass phase is composed of at least one of the following items (A), (B), (C), (D), (E), and (F): (A) Li-MO (wherein M is at least one element selected from the group consisting of fluorine (F), chlorine (Cl), bromine (Br), and iodine (I)); (B) Li 2 O-RO x (wherein R is at least one element selected from boron (B), aluminum (Al), silicon (Si), germanium (Ge), phosphorus (P), and arsenic (As), and x=1 to 3). (C) LLTO (Li-La-Ti-O), (D) LLZO (Li-La-Zr-O), (E) LiPON (lithium phosphorus oxynitride), (F)Li 2 SP 2 WITH 5

5. The NCM positive electrode particles coated with the LLZO and glass phases described in claim 1, characterized in that the lateral size of the LLZO fine particles is in the range of 50 nm to 300 nm, and the lateral size is the size along the spherical surface direction of the corresponding NCM large particle.

6. The NCM positive electrode particle coated with LLZO and a glass phase as described in claim 1, characterized in that in the composite NCM particle, the total weight ratio of the plurality of LLZO microparticles and the NCM particle having the glass phase is in the range of 0.2% to 2%.

7. The NCM positive electrode particle coated with LLZO and a glass phase as described in claim 1, further comprising a plurality of carbon nanotubes (CNTs) coating the outer periphery of the composite NCM particle, and the carbon nanotubes and the composite NCM particles form a positive electrode particle coated with the carbon nanotubes.

8. The NCM positive electrode particle coated with LLZO and a glass phase according to claim 7, characterized in that the plurality of carbon nanotubes include 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 1 μm and each of the long-chain carbon nanotubes having a length in the range of 3 μm to 8 μm, the plurality of short-chain carbon nanotubes being used to bridge the LLZO fine particles and the NCM large particles, and the plurality of long-chain carbon nanotubes being used to coat the composite NCM particles so that the entire composite NCM particle has suitable electrical conductivity.

9. The NCM positive electrode particles coated with LLZO and glass phases according to claim 7, characterized in that the total weight ratio of the carbon nanotubes and the composite NCM particles is in the range of 0.1% to 2%.

10. 8. The NCM positive electrode particle coated with LLZO and a glass phase according to claim 7, further comprising a plurality of nanoscale amorphous carbons coating the exterior of the positive electrode particles coating the carbon nanotubes, wherein the plurality of nanoscale amorphous carbons and the positive electrode particles coating the carbon nanotubes form positive electrode particles coated with a carbon material, and each of the nanoscale amorphous carbons is located in a gap formed by the intersection of the plurality of carbon nanotubes.

11. The NCM positive electrode particles coated with LLZO and glass phases as described in claim 10, characterized in that the size of each of the nanoscale amorphous carbons ranges between 20 nm and 100 nm.

12. The NCM positive electrode particles coated with LLZO and glass phases according to claim 10, characterized in that the total weight ratio of the nanoscale amorphous carbon and the composite NCM particles is in the range of 0.1% to 2%, and the nanoscale amorphous carbon serves as a conductive additive.

13. The NCM positive electrode particles coated with LLZO and a glass phase according to claim 10, characterized in that the weight ratio of the total weight of the carbon nanotubes and the nanoscale amorphous carbons to the weight of the composite NCM particles is (0.09-3):

100.

14. 11. The NCM positive electrode particles coated with LLZO and a glass phase as described in claim 10, characterized in that the weight ratio of the plurality of carbon nanotubes, the plurality of nanoscale amorphous carbons, and the composite NCM particles is 0.5:1:

100.

15. a+b=0.25-0.8, a>0.

1. By doping copper in LLZO, the entire structure is further stabilized, the lithium ion channel is made smoother, the sintering speed is increased, and the manufacturing cost is very low. When the LLZO particles are exposed to air, lithium carbonate (Li 2 CO 3 2. The NCM positive electrode particles coated with LLZO and glass phase according to claim 1, characterized in that the formation of LLZO and glass phase is reduced, i.e., the surface stability of the entire material is improved during sintering.

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