NCM electrode particles coated with interphase layer and nitrogen-containing carbon layer

Abstract

NCM electrode particles coated with an interphase layer and a nitrogen-containing carbon layer; the NCM electrode particle is used in an electrode of a solid-state battery or a semi-solid-state battery; the NCM electrode particle comprises: an NCM particle (lithium nickel manganese cobalt oxide) with a single-crystalline structure; The interphase layer is applied to the outer surface of the NCM particle; the NCM particle coated with the interphase layer forms a primary particle; the interphase layer comprises a glass phase layer and several ceramic particles dispersed therein; the interphase layer serves to protect the NCM particle and increase lithium ion conductivity; a nitrogen-containing carbon layer is applied to the outside of the primary particle; the NCM electrode particle is formed by the NCM particle, the interphase layer, and the nitrogen-containing carbon layer; the nitrogen-containing carbon layer serves to increase the electrical conductivity of the NCM electrode particle; and wherein nitrogen-doped carbon molecules in the nitrogen-containing carbon layer increase the electronic conductivity and lithium ion conductivity of the NCM particles and change the electrical potential of the NCM particles; the nitrogen-containing carbon layer is formed by calcining a nitrogen-containing polymer material in an inert atmosphere and coated on the outer surface of the primary particle; carbon and nitrogen in the nitrogen-containing carbon layer form conjugated C=N bonds to change an energy band and thus reduce the energy required to excite electrons into a conduction band, thereby increasing the electrical conductivity.

Description

FIELD OF THE INVENTION

[0001] The invention relates to electrolyte particles and, in particular, to an NCM electrode particle coated with an interphase layer and a nitrogen-containing carbon layer. BACKGROUND OF THE INVENTION

[0002] A typical battery consists primarily of positive and negative electrodes in an electrolyte. The positive electrode is formed by mixing and dispersing a large number of positive conductive units (positive electrode material, e.g., lithium cobalt oxide) in a positive suspension. The positive conductive units are interconnected by the conductive suspension. Therefore, the conductive suspension must have sufficient conductivity to allow free electrons to migrate between the various positive conductive units, and the internal resistance must not consume too much energy to ensure effective conductivity. Therefore, the use of a special conductive material to prepare the suspension is necessary to adjust the conductivity.

[0003] To increase conductivity, the positive suspension is filled with several positive electrode particles, which can consist of mixtures of NCM (lithium nickel manganese cobalt oxide) or LMFP (lithium manganese iron phosphate). However, side reactions easily occur at the interface of conventional positive electrode particles, which shorten the lifespan of the positive electrode. Furthermore, sintering during production easily leads to decomposition, resulting in lower electrical conductivity and poor battery performance. SUMMARY OF THE INVENTION

[0004] To remedy the above-mentioned deficiencies of the prior art, the object of the invention is to provide an NCM electrode particle coated with an interphase layer and a nitrogen-containing carbon layer. The interphase layer is located on the outer side of the NCM particle to reduce the risk of degradation of the NCM particle by the inert gases used in its production. The interphase layer can also increase lithium ion conductivity. Furthermore, the nitrogen-containing carbon layer is applied to the outer side of the interphase layer to increase the electrical conductivity of the NCM electrode particle. BRIEF DESCRIPTION OF THE ILLUSTRATIONS Fig. shows a cross-section of the structure of the NCM electrode particle according to the invention. Fig. shows an enlarged schematic view of the structure of the NCM electrode particle according to the invention. Fig. shows a schematic view of the structure of the nitrogen-containing carbon layer according to the invention Fig. shows a schematic view of an application of the invention. Fig. shows a schematic view of the structure of the second-order NCM composite particle according to the invention. DETAILED DESCRIPTION OF THE INVENTION

[0005] With reference to the Fig. The invention relates to an NCM electrode particle 100 coated with an interphase layer and a nitrogen-containing carbon layer, which can be used for an electrode 10 of a solid-state battery or a semi-solid-state battery. In the application, several NCM electrode particles 100 can be arranged within the electrode 10. Preferably, the electrode 10 represents a positive (+) electrode. The NCM electrode particle 100 has a particle size of less than 10 µm. With reference to Fig. The electrode 10 comprises a positive substrate 11 and a positive mass layer 13 coated on the positive substrate 11. The positive mass layer 13 comprises the NCM electrode particles 100 and a positive electrode mass 12, which serves as a binder. The weight fraction of the NCM electrode particles 100 in the positive slurry layer 13 is 80-98 wt.%. According to Fig. The NCM electrode particle 100 contains the following elements: An NCM (lithium nickel manganese cobalt oxide) 15 particle has a single-crystal structure. NCM is a ternary oxide. The D50 value (mass median diameter, MMD) of the NCM 15 particle is 3 to 5 µm. The D90 value of the NCM 15 particle is a maximum of 10 µm.

[0006] The outer surface of the NCM particle 15 is coated with an interphase layer 16. The NCM particle 15 coated with the interphase layer 16 forms a primary particle 30.

[0007] The interphase layer 16 comprises a glass phase layer 241 and a plurality of ceramic particles 242 dispersed therein. The interphase layer 16 serves to protect the NCM particle 15 and increases lithium ion conductivity. The particle size of the ceramic particles 242 is less than 100 nm each. The radial thickness of the glass phase layer 241 is 50 nm to 1 µm. The radial thickness of the interphase layer 16 is also 50 nm to 1 µm. In the interphase layer 16, the ratio of the total weight of the ceramic particles 242 to the weight of the glass phase layer 241 is 10-1:1-10.

[0008] The glass phase layer 241 consists of an amorphous oxide, which is formed by heat treatment and has a lithium ion conductivity of over 10 -5S / cm (Siemens per centimeter). The amorphous oxide can be a lithium-containing oxide or an amorphous oxide-based solid electrolyte. The lithium-containing oxide consists of lithium (Li) and a chemical element from Group IIIA (boron group), Group IVA (carbon group), or Group VA (nitrogen group) of the periodic table. The lithium can be Li2O-RO x where x=1 to 3 and R is selected from boron (B), aluminum (Al), silicon (Si), germanium (Ge), phosphorus (P) and arsenic (As).

[0009] The amorphous oxide-based solid electrolyte is selected from at least one of the following compounds: an amorphous perovskite solid electrolyte (Li-La-Ti-O, lithium lanthanum titanium oxide, LLTO), a garnet-based solid electrolyte (such as Li-La-Zr-O, lithium lanthanum zirconium oxide, LLZO), a lithium phosphorus oxynitride (LiPON), and lithium aluminum titanium phosphate (LATP).

[0010] The glass phase layer 241 has an unspecified element arrangement. Furthermore, the glass phase layer 241 is a continuous thin film applied to the outer surface of the NCM particle 15.

[0011] The ceramic particles 242 consist of an oxide with protective effect (such as Al2O3 or SiO x (0 <x≤2)) oder einem Keramikoxid, welches die Lithiumionenleitfähigkeit erhöhen kann (wie ein Festelektrolytmaterial).

[0012] The solid electrolyte material consists of a first, lithium-ion-conducting oxide or phosphate or a second oxide with a garnet or perovskite structure. The lithium-ion conductivity of the first oxide or phosphate is greater than 10 -6 cm 2 / s (diffusion coefficient). The first oxide or phosphate can be LATP (lithium aluminum titanium phosphate) with NASICON structure (sodium (Na) superionic conductor), LAGP (lithium aluminum germanium phosphate), or lithiophosphate (Li3PO4). The second oxide with garnet or perovskite structure can be LLZO (Li7La3Zr2O 12 , lithium lanthanum zirconium oxide) or LLTO (lithium lanthanum titanium oxide). The ceramic particles 242 can be formed by combining the above-mentioned materials in any ratio.

[0013] The NCM electrode particle 100 is manufactured by sintering in an inert atmosphere. Since NCM easily decomposes in an inert atmosphere and impairs battery performance, the interphase layer 16 serves to protect the NCM particle 15. The interphase layer 16 is less sensitive to oxygen and stable in an inert atmosphere, thereby protecting the NCM particle 15 from the effects of the inert atmosphere.

[0014] On the outside of the primary particle 30 there is a nitrogen-containing carbon layer 35. The NCM electrode particle 100 consists of the NCM particle 15, the interphase layer 16 and the nitrogen-containing carbon layer 35, as shown in Fig. The radial thickness of the nitrogen-containing carbon layer 35 is at most 0.2 µm. The nitrogen-containing carbon layer 35 serves to increase the electrical conductivity of the NCM electrode particle 100. As Fig. As shown, the nitrogen-containing carbon layer 35 consists of a multitude of highly ordered carbon structures with C=N double bonds (carbon-nitrogen double bonds). The highly ordered carbon structures are connected via hydrogen bonds to lone electron pairs (valence electron pairs) of oxygen ions on the outer surface of the interphase layer 16, thus forming the nitrogen-containing carbon layer 35 on the outside of the primary particle 30.

[0015] The purpose of coating the outer surface of the primary particle 30 with the nitrogen-containing carbon layer 35 is for the nitrogen-doped carbon molecules in the nitrogen-containing carbon layer 35 to increase the electrical conductivity and lithium ion conductivity of the NCM particles 15 and change the electrical potential of the NCM particles 15, thus improving the performance of the entire battery. The nitrogen-containing carbon layer 35 is formed by calcining a nitrogen-containing polymer material in an inert atmosphere and is applied to the outer surface of the primary particle 30. The nitrogen-containing polymer material can be polydopamine (PDA) or any material capable of forming conjugated C=N bonds (an unsaturated conjugated system of carbon and nitrogen) upon calcination.Carbon and nitrogen form the conjugated C=N bonds to change the energy band and reduce the energy required to excite electrons into the conduction band, which increases electrical conductivity.

[0016] Referring to Fig. An outer surface of the NCM electrode particle 100 is further coated with a plurality of carbon nanotubes 40 and a plurality of nanoscale amorphous carbons 45 to form a second-order NCM composite particle 50. Each of the carbon nanotubes 40 has a length of 200 to 500 nm. Each of the nanoscale amorphous carbons 45 has a length of 10 to 40 nm. The nanoscale amorphous carbons 45 are amorphous carbons of a super-P aid.

[0017] The ratio of the total weight of the carbon nanotubes 40 and the nanoscale amorphous carbons 45 to the weight of the NCM particle 15 is 0.2-2:99.8-98.

[0018] The carbon nanotubes 40 increase the electron conductivity. They are randomly distributed on the outer surfaces of the NCM electrode particle 100. They also exhibit extremely high electrical conductivity, allowing electrons to pass through the carbon nanotubes 40 and conduct between different NCM electrode particles 100, increasing the electrical conductivity of the electrode 10.

[0019] The carbon nanotubes 40 and the nanoscale amorphous carbons 45 serve as auxiliary materials. The nanoscale amorphous carbons 45 are in the form of particles, and the carbon nanotubes 40 are in the form of long strips. The nanoscale amorphous carbons 45 fill the spaces between the carbon nanotubes 40 to transfer the electric charge between the carbon nanotubes 40 through the overpotential of the nanoscale amorphous carbons 45, which further increases the electric current transfer efficiency.

[0020] An NCM electrode particle coated with an interphase layer and a nitrogen-containing carbon layer consists of an NCM particle (lithium nickel manganese cobalt oxide) and the interphase layer applied to its outer surface. The NCM particle coated with the interphase layer forms a primary particle. The interphase layer consists of a glass phase layer and several ceramic particles dispersed therein. The nitrogen-containing carbon layer is located on the outer surface of the primary particle. The nitrogen-containing carbon layer increases the electrical conductivity of the NCM electrode particle.

[0021] Having described the invention above, it is obvious that it is susceptible to numerous variations. Such variations do not constitute a departure from the spirit and scope of the invention, and all modifications obvious to one skilled in the art are intended to be within the scope of the following claims.

Claims

[1] NCM electrode particle coated with an interphase layer and a nitrogen-containing carbon layer; the NCM electrode particle is used in an electrode of a solid-state battery or a semi-solid-state battery; the NCM electrode particle comprises: an NCM particle (lithium nickel manganese cobalt oxide) with a single-crystalline structure; The interphase layer is applied to the outer surface of the NCM particle; the NCM particle coated with the interphase layer forms a primary particle; the interphase layer comprises a glass phase layer and several ceramic particles dispersed therein; the interphase layer serves to protect the NCM particle and increase lithium ion conductivity; a nitrogen-containing carbon layer is applied to the outside of the primary particle; the NCM electrode particle is formed by the NCM particle, the interphase layer, and the nitrogen-containing carbon layer; the nitrogen-containing carbon layer serves to increase the electrical conductivity of the NCM electrode particle; and wherein nitrogen-doped carbon molecules in the nitrogen-containing carbon layer increase the electronic conductivity and lithium ion conductivity of the NCM particles and change the electrical potential of the NCM particles; the nitrogen-containing carbon layer is formed by calcining a nitrogen-containing polymer material in an inert atmosphere and coated on the outer surface of the primary particle; carbon and nitrogen in the nitrogen-containing carbon layer form conjugated C=N bonds to change an energy band and thus reduce the energy required to excite electrons into a conduction band, thereby increasing the electrical conductivity. [2] NCM electrode particles according to claim 1, wherein the nitrogen-containing carbon layer consists of a plurality of highly ordered carbon structures having C=N double bonds; and the highly ordered carbon structures are hydrogen-bonded to lone pairs of oxygen ions on the outer surface of the interphase layer, which form the nitrogen-containing carbon layer. [3] NCM electrode particles according to claim 1, wherein the D50 (mass median diameter, MMD) of the NCM particle is 3 to 5 µm; the particle size of each ceramic particle is less than 100 nm; the radial thickness of the glass phase layer is 50-1 µm; the radial thickness of the interphase layer is 50 nm to 1 µm; and in the interphase layer, the ratio of the total weight of the ceramic particles to the weight of the glass phase layer is 10-1:1-10. [4] NCM electrode particles according to claim 1, wherein the glass phase layer consists of an amorphous oxide formed by heat treatment and has a lithium ion conductivity of over 10 -5 S / cm (Siemens per centimeter); the glass phase layer has an unspecified elemental arrangement and represents a continuous thin film coated on the outer surface of the NCM particle. [5] NCM electrode particles according to claim 4, wherein the amorphous oxide consists of lithium (Li) and a chemical element of group IIIA (boron group), group IVA (carbon group) or group VA (nitrogen group) of the periodic table. [6] NCM electrode particles according to claim 5, wherein the amorphous oxide is Li2O-RO5, where x=1 to 3 and R is selected from boron (B), aluminum (Al), silicon (Si), germanium (Ge), phosphorus (P) and arsenic (As). [7] NCM electrode particles according to claim 1, wherein the ceramic particles consist of an oxide with a protective effect or a ceramic oxide which can increase the lithium ion conductivity. [8] NCM electrode particles according to claim 7, wherein the ceramic particles consist of Al2O3 or SiO5, wherein 0 <x≤2 ist. [9] NCM electrode particles according to claim 7, wherein the ceramic particles consist of a solid electrolyte material. [10] NCM electrode particles according to claim 9, wherein the solid electrolyte material consists of a first lithium ion-conducting oxide or phosphate or a second oxide with a garnet or perovskite structure; the lithium ion conductivity of the first oxide or phosphate is above 10 -5 cm 2 / s (diffusion coefficient). [11] NCM electrode particles according to claim 10, wherein the first oxide or phosphate is selected from LATP (lithium aluminum titanium phosphate) with NASICON structure (sodium (Na) super ion conductor) or LAGP (lithium aluminum germanium phosphate). [12] NCM electrode particles according to claim 10, wherein the second oxide with garnet or perovskite structure is made of LLZO (Li7La3Zr2O 12 , lithium lanthanum zirconium oxide) or LLTO (lithium lanthanum titanium oxide) is selected. [13] NCM electrode particles according to claim 1, wherein the radial thickness of the nitrogen-containing carbon layer is less than or equal to 0.2 µm. [14] NCM electrode particles according to claim 1, wherein the nitrogen-containing polymer material is polydopamine (PDA) or a special material that can produce conjugated C=N bonds by calcination. [15] The NCM electrode particle according to claim 1, wherein the outer surface of the NCM electrode particle is additionally coated with a plurality of carbon nanotubes and a plurality of nanoscale amorphous carbons. [16] NCM electrode particles according to claim 15, wherein each of the carbon nanotubes has a length of 200 to 500 nm and each of the nanoscale amorphous carbons has a length of 10 to 40 nm. [17] NCM electrode particles according to claim 15, wherein the ratio of the total weight of the carbon nanotubes and the nanoscale amorphous carbons to the weight of the NCM particle is 0.2-2:99.8-98.

Images