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US-20260128275-A1 - METHOD FOR MANUFACTURING LMFP COMPOSITE POSITIVE ELECTRODE PARTICLES

US20260128275A1US 20260128275 A1US20260128275 A1US 20260128275A1US-20260128275-A1

Abstract

A method for manufacturing LMFP composite positive electrode particles includes the steps of: placing a plurality of lithium ion conductor particles and LMFP particles, a carbon source and a first dispersant into a ball mill for mixing to form a mixed slurry, wherein each of the lithium ion conductor particles formed by a first oxide or phosphate capable of conducting lithium ions, or is formed by a second oxide with a garnet structure or a perovskite structure; then performing a drying on the mixed slurry to obtain a plurality of mixture powders; and then placing the mixture powders into a sintering furnace for performing an oxygen-free sintering to cause that the carbon source performs a dehydration reaction to produce carbons and other residues to form a conductive layer coated on the outer surface of each of the LMFP particles.

Inventors

  • ZHI FENG LUO

Assignees

  • ZHI FENG LUO

Dates

Publication Date
20260507
Application Date
20241107

Claims (20)

  1. 1 . A method for manufacturing LMFP composite positive electrode particles; the composite positive electrode particles being used in a positive electrode of a solid-state or semi-solid battery; the method comprising the steps of: step A: placing a plurality of lithium ion conductor particles, a plurality of LMFP particles, a carbon source and a first dispersant into a ball mill for mixing to form a mixed slurry; wherein each of the lithium ion conductor particles is formed by a first oxide or phosphate capable of conducting lithium ions, or is formed by a second oxide with a garnet structure or a perovskite structure; a lithium ion conductivity of the first oxide or phosphate is higher than 10 −5 S/cm (Siemens per centimeter); and the carbon source is formed by an organic compound capable of forming a conducting carbon structure under a reduction atmosphere; step B: performing a natural drying or a vacuum drying on the mixed slurry to obtain a plurality of mixture powders; step C: placing the mixture powders into a sintering furnace for performing an oxygen-free sintering on the mixture powders to form the composite positive electrode particles; wherein in the oxygen-free sintering, the carbon source in the mixture powders performs a dehydration reaction to produce carbons and other residues after the oxygen-free sintering; the carbons and residues remaining after the oxygen-free sintering form a conductive layer and the conductive layer is coated on an outer surface of each of the LMFP particles; and the lithium ion conductor particles on each of the LMFP particles form a continuous layer structure or a discontinuously dispersed structure or an island-shaped structure.
  2. 2 . The method for manufacturing the LMFP composite positive electrode particles as claimed in claim 1 , wherein the first oxide or phosphate with the lithium ion conductivity may be LATP (lithium aluminum titanium phosphate) with a NASICON (sodium (Na) super ionic conductor) structure, LAGP (lithium aluminium germanium phosphate), or lithiophosphate (Li 3 PO 4 ).
  3. 3 . The method for manufacturing the LMFP composite positive electrode particles as claimed in claim 1 , wherein the second oxide with the garnet structure or the perovskite structure may be LLZO (Li 7 La 3 Zr 2 O 12 , lithium lanthanum zirconium oxide) or LLTO (lithium lanthanum titanium oxide).
  4. 4 . The method for manufacturing the LMFP composite positive electrode particles as claimed in claim 1 , wherein a D50 (mass-median-diameter, MMD) value of each of the LMFP particles is less than 1 μm; and each of the LMFP particles is a polymer of monocrystalline materials or microcrystalline particles; and a thickness of the conductive layer is less than or equal to 200 nm.
  5. 5 . The method for manufacturing the LMFP composite positive electrode particles as claimed in claim 1 , wherein each of the LMFP particles is formed by LMFP (lithium manganese iron phosphate, LiMn x Fe 1−x PO 4 , 0.1≤x≤0.8) or LMFP doped with at least one metal.
  6. 6 . The method for manufacturing the LMFP composite positive electrode particles as claimed in claim 1 , wherein in the step A, before placing the lithium ion conductor particles into the ball mill, an outer surface of each of the lithium ion conductor particles is coated with a borate layer to cause that the lithium ion conductor particles form a plurality of lithium ion composite conductor particle.
  7. 7 . The method for manufacturing the LMFP composite positive electrode particles as claimed in claim 6 , wherein the borate layer is formed by grinding the lithium ion conductor particles to cause that the D50 value of each of the lithium ion conductor particles is less than 200 nm, then mixing the lithium ion conductor particles with a solution having boric acid to form a mixture, and then performing a drying and a grinding on the mixture or performing a drying, a sintering and a grinding on the mixture, causing that each of the outer surface of each of the lithium ion conductor particles is coated with the borate layer.
  8. 8 . The method for manufacturing the LMFP composite positive electrode particles as claimed in claim 1 , wherein the organic compound is selected from monosaccharide, disaccharide, oligosaccharide and polysaccharide, water-soluble fiber and amino acid polymer; wherein in the oxygen-free sintering of the step C, when the carbon source is formed by carbohydrates, the carbons are left behind after a dehydration reaction of the carbohydrates; when the carbon source is formed by water-soluble fibers, carbon skeletons and functional groups are left behind after a dehydration reaction of the water-soluble fibers; a structure of the carbon skeletons is determined by a structure of the original water-soluble fibers; and when the carbon source is formed by amino acid polymers, carbon skeletons with straight chains or side chains containing doping elements are left behind after a dehydration reaction of the amino acid polymers.
  9. 9 . The method for manufacturing the LMFP composite positive electrode particles as claimed in claim 1 , wherein the organic compound is a compound including carbon, nitrogen, fluorine, phosphorus and sulfur, wherein the nitrogen, fluorine, phosphorus and sulfur are doped to the carbon by a reduction reaction.
  10. 10 . The method for manufacturing the LMFP composite positive electrode particles as claimed in claim 1 , wherein the carbon source further includes at least one of graphite, graphene, nanoscale amorphous carbons, and carbon nanotubes with a length less than or equal to 1 μm.
  11. 11 . The method for manufacturing the LMFP composite positive electrode particles as claimed in claim 1 , wherein a ratio of a weight of the carbon source and a total weight of the lithium ion conductor particles is 10:1 to 1:10; a quotient of a ratio of a total weight of the lithium ion conductor particles and a total weight of the LMFP particles is less than or equal to 0.02; a quotient of a ratio of a weight of the carbon source and the total weight of the LMFP particles is less than or equal to 0.01; and a weight percentage of the lithium ion conductor particles, the LMFP particles and the carbon source in the mixed slurry is less than or equal to 35 wt %.
  12. 12 . The method for manufacturing the LMFP composite positive electrode particles as claimed in claim 1 , wherein each of the lithium ion conductor particles is formed by at least one of LLZO (Li 7 La 3 Zr 2 O 12 ), Ga-LLZO (gallium-doped LLZO), Cu-LLZO (copper-doped LLZO), Ta-LLZO (tantalum-doped LLZO), Sr-LLZO (strontium-doped LLZO) and Al-LLZO (aluminum-doped LLZO).
  13. 13 . The method for manufacturing the LMFP composite positive electrode particles as claimed in claim 1 , wherein each of the lithium ion conductor particles is formed by Cu a ,X b -LLZO, which is LLZO doped with copper (Cu) and a metal X, wherein X is selected from gallium (Ga), tantalum (Ta), strontium (Sr), barium (Ba) and aluminum (Al), a+b=0.25˜0.8 and a>0.1.
  14. 14 . The method for manufacturing the LMFP composite positive electrode particles as claimed in claim 1 , wherein when each of the lithium ion conductor particles is formed by LAGP (lithium aluminium germanium phosphate) or LATP (lithium aluminum titanium phosphate), the LAGP or LATP is selected from Li 1+x Al x A 2−x (PO 4 ) 3 or Li 1+x+y Al x A 2−x−y−z M y N z (PO 4 ) 3 , wherein 0.1≤x≤0.8, 0≤y≤0.2, 0≤z≤0.2, A is germanium (Ge) or titanium (Ti), M is trivalent cation, and N is tetravalent cation.
  15. 15 . The method for manufacturing the LMFP composite positive electrode particles as claimed in claim 1 , wherein the ball mill is a wet ball mill, wherein the wet ball mill is a blade ball mill or a ball mill with zirconium balls; in the step A, a rotation speed of the ball mill is 200 rpm˜1000 rpm; a grinding time of the ball mill is 2 to 10 hours; and a grinding temperature of the ball mill is a room temperature.
  16. 16 . The method for manufacturing the LMFP composite positive electrode particles as claimed in claim 1 , wherein in the step C, a sintering temperature of the sintering furnace is 400° C.˜700° C.; a sintering time of the sintering furnace is 1 to 10 hours; and the oxygen-free sintering is a vacuum sintering or is a sintering under a protective atmosphere.
  17. 17 . The method for manufacturing the LMFP composite positive electrode particles as claimed in claim 1 , further comprising the step of: step D: performing a sifting for the composite positive electrode particles to remove impurities and obtain a plurality of composite positive electrode particle powders.
  18. 18 . The method for manufacturing the LMFP composite positive electrode particles as claimed in claim 17 , further comprising the step of: step E: placing the composite positive electrode particle powders and a first slurry which includes a carbon material into a mixer for mixing to form a plurality of carbon-material-coated composite positive electrode particles; and wherein the carbon material includes a plurality of first carbon nanotubes and a plurality of nanoscale amorphous carbons.
  19. 19 . The method for manufacturing the LMFP composite positive electrode particles as claimed in claim 18 , wherein in the step E, a rotation speed of the mixer is 50 rpm˜1000 rpm; a mixing time of the mixer is 1 to 3 hours; and the mixer is a DC stirrer or a vacuum emulsifying mixer.
  20. 20 . The method for manufacturing the LMFP composite positive electrode particles as claimed in claim 18 , wherein a weight percentage of the carbon material in the first slurry is less than or equal to 5 wt %; a solvent in the first slurry is selected from water, ethanol, isopropyl alcohol and NMP (N-Methyl-2-pyrrolidone); the first slurry further includes a second dispersant, wherein the second dispersant is selected from SCS (sodium o-cumenesulfonate) and sinapinic acid; and a weight percentage of the second dispersant in the first slurry is less than or equal to 1 wt %; the first carbon nanotubes include a plurality of short chain carbon nanotubes and a plurality of long chain carbon nanotubes; a length of each of the short chain carbon nanotubes is 0.2 μm to 1 μm; a length of each of the long chain carbon nanotubes is 1 μm to 3 μm; and a size of each of the nanoscale amorphous carbons is 10 nm to 40 nm.

Description

FIELD OF THE INVENTION The present invention is related to a positive electrode material for a battery, and in particular to a method for manufacturing LMFP composite positive electrode particles. BACKGROUND OF THE INVENTION A typical battery includes a positive electrode and a negative electrode. A cathode of the battery is the positive electrode inside the battery. The positive electrode of a solid-state or semi-solid battery includes a positive electrode substrate and a positive electrode slurry layer. The positive electrode slurry layer includes a positive electrode slurry and a plurality of positive electrode particles. The positive electrode particles must be either additionally conductive or electrically conductive to allow free electrons to migrate through the positive electrode slurry without consuming too much energy due to internal resistance. Material of the positive electrode particles may be LMFP (lithium manganese iron phosphate), which has a better working voltage performance than LFP (lithium iron phosphate), releases higher energy density, is inexpensive, and is hydrophobic. However, LMFP has a poor charge-discharge rate performance and a lower lithium ion conductivity and electrical conductivity, and it is prone to deterioration under prolonged battery use. Although there are many ways to increase the lithium ion conductivity of positive electrode particles, the electrical conductivity is still insufficient for practical use. Therefore, the present invention desires to provide a novel invention to increase the electrical capacity and electrical conductivity of positive electrode of solid-state or semi-solid battery. SUMMARY OF THE INVENTION Accordingly, for improving above mentioned defects in the prior art, the object of the present invention is to provide a method for manufacturing LMFP composite positive electrode particles, wherein the LMFP particle is coated by a conductive layer to increase the overall performance. The cost of LMFP is lower than the ternary oxide and the charge and discharge performance of LMFP can be applied to a specific range of applications. The conductive layer on the outer surface of the LMFP particle compensates for the lower conductivity of LMFP, and the LMFP particle are also coated with lithium ion conducting particles to enhance the overall lithium ion conductivity and electrical conductivity, resulting in a better battery performance. To achieve above object, the present invention provides a method for manufacturing LMFP composite positive electrode particles; the composite positive electrode particles being used in a positive electrode of a solid-state or semi-solid battery; the method comprising the steps of: step A: placing a plurality of lithium ion conductor particles, a plurality of LMFP particles, a carbon source and a first dispersant into a ball mill for mixing to form a mixed slurry; wherein each of the lithium ion conductor particles is formed by a first oxide or phosphate capable of conducting lithium ions, or is formed by a second oxide with a garnet structure or a perovskite structure; a lithium ion conductivity of the first oxide or phosphate is higher than 10−5 S/cm (Siemens per centimeter); and the carbon source is formed by an organic compound capable of forming a conducting carbon structure under a reduction atmosphere; step B: performing a natural drying or a vacuum drying on the mixed slurry to obtain a plurality of mixture powders; step C: placing the mixture powders into a sintering furnace for performing an oxygen-free sintering on the mixture powders to form the composite positive electrode particles; wherein in the oxygen-free sintering, the carbon source in the mixture powders performs a dehydration reaction to produce carbons and other residues after the oxygen-free sintering; the carbons and residues remaining after the oxygen-free sintering form a conductive layer and the conductive layer is coated on an outer surface of each of the LMFP particles; and the lithium ion conductor particles on each of the LMFP particles form a continuous layer structure or a discontinuously dispersed structure or an island-shaped structure. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a steps flow diagram showing the process of the present invention. FIG. 2 is a steps flow diagram showing the process of step A of the present invention. FIG. 3 is a steps flow diagram showing the processes of step B to step E of the present invention. FIG. 4 is a schematic view showing an application of the present invention. FIG. 5 is a schematic view showing the full structure and a partial structure of the composite positive electrode particle of the present invention. FIG. 6 is a cross-section view showing the structure of the composite positive electrode particle of the present invention. FIG. 7 is a schematic view showing the carbon-material-coated composite positive electrode particle of the present invention. FIG. 8 is a schematic view showing the lithium