Method for manufacturing conductive particles for conducting ions and electrons of positive or negative electrode

1 . A method for manufacturing conductive particles for conducting ions and electrons of a positive or negative electrode comprising the steps of:

step 500 : mixing and grinding a plurality of ceramic particles and a first alcohol solution under a protection of a nitrogen atmosphere by using a mill;

step 510 : adding a plurality of lithium fluoride (LiF) particles and an organic material into the mill; then mixing and grinding the lithium fluoride particles, the organic material, the ceramic particles and the first alcohol solution to form a first mixed slurry by using the mill;

step 520 : mixing a second alcohol solution, polyvinylpyrrolidone, sodium dodecyl sulfate, a plurality of first carbon nanotubes and a plurality of graphene sheets to form a second mixed slurry by using a first mixer;

step 530 : placing the second mixed slurry into the mill and then mixing and grinding the second mixed slurry and the first mixed slurry by using the mill;

step 540 : placing the second mixed slurry and the first mixed slurry into a rotary evaporator; and then removing the first alcohol solution and the second alcohol solution from the second mixed slurry and the first mixed slurry to form a mixture powder by using the rotary evaporator;

step 550 : placing the mixture powder into a sintering furnace and perform a sintering on the mixture powder under a nitrogen atmosphere to form a plurality of conductive particles by using the sintering furnace; wherein each of the conductive particles includes a corresponding ceramic particle and an amorphous carbon layer coated on an outer side of the corresponding ceramic particle; the amorphous carbon layer includes a plurality of corresponding lithium fluoride particles, a plurality of corresponding graphene sheets and a plurality of corresponding first carbon nanotubes; in the sintering, a temperature of the sintering furnace is gradually increased to a specific value; the organic material, the polyvinylpyrrolidone and the sodium dodecyl sulfate in the mixture powder form a plurality of amorphous carbons; the amorphous carbon layer is formed by the amorphous carbons and is coated on an outer surface of the corresponding ceramic particle; and the lithium fluoride particles, the graphene sheets and the first carbon nanotubes are dispersed within the corresponding amorphous carbon layer; and

wherein each of the graphene sheets has a sheet structure; the graphene sheets form a multilayer structure to wrap around an outer side of the corresponding ceramic particle; the first carbon nanotube are dispersed in gaps between the corresponding graphene sheets and the corresponding ceramic particle and in gaps between different graphene sheets to be used as bridges between the graphene sheets and the ceramic particle; and the lithium fluoride particles are used as bridges for guiding the lithium ions through the conductive particle.

2 . The method as claimed in claim 1 , wherein each of the ceramic particles is formed by at least one of a first ceramic oxide or phosphate capable of conducting lithium ions, a second oxide with a garnet structure or a perovskite structure, and sulfide; and a lithium ion conductivity of the first ceramic oxide or phosphate is higher than 10 −3 cm 2 /s.

3 . The method as claimed in claim 2 , wherein the second oxide is selected from LLZO (Li 7 La 3 Zr 2 O 12 , lithium lanthanum zirconium oxide) and LLTO (lithium lanthanum titanium oxide).

4 . The method as claimed in claim 1 , wherein each of the ceramic particles is formed by LLZO (Li 7 La 3 Zr 2 O 12 ).

5 . The method as claimed in claim 1 , wherein each of the ceramic 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).

6 . The method as claimed in claim 1 , wherein a particle size of each of the ceramic particles is less than 30 μm before the mixing and grinding of the mill in the step A; and the particle size of each of the ceramic particles is less than 500 nm after the mixing and grinding of the mill in the step A.

7 . The method as claimed in claim 1 , wherein the first alcohol solution is formed by ethanol or isopropyl alcohol; and the second alcohol solution is formed by ethanol or isopropyl alcohol.

8 . The method as claimed in claim 1 , wherein after the step B, the particle size of each of the ceramic particles is less than 150 nm; a ratio of a total weight of the ceramic particles, a weight of the organic material, and the weight of the first alcohol solution is 0.99:0.01:4; a ratio of the total weight of the ceramic particles and a total weight of the lithium fluoride particles is 99.9~99.95:0.1~0.05.

9 . The method as claimed in claim 1 , wherein the organic material is formed by at least one of an organic resin, an organic compound, a carbohydrate, a water-soluble fiber and an amino acid polymer;

wherein when the organic material is formed by the organic resin, the amorphous carbons are hard carbons or soft carbons formed by a de-esterification of the organic material in the sintering of the step F;

wherein when the organic material is formed by the organic compound, the amorphous carbons are formed under the reduction atmosphere in the sintering of the organic material in the step F, or are hard carbons or soft carbons formed by a de-esterification of the organic material in the sintering of the step F;

wherein when the organic material is formed by the carbohydrate, the amorphous carbons are formed by a dehydration of the organic material in the sintering of the step F;

wherein when the organic material is formed by the water-soluble fiber, the amorphous carbons are formed by a dehydration of the organic material in the sintering of the step F and have carbon skeletons and functional groups; and

wherein when the organic material is formed by the amino acid polymer, the amorphous carbons are formed by a dehydration of the organic material in the sintering of the step F and have carbon skeletons with straight chains or side chains containing doping elements.

10 . The method as claimed in claim 9 , wherein the organic compound is selected from monosaccharide, disaccharide, oligosaccharide, polysaccharide, water-soluble fiber and amino acid polymer.

11 . The method as claimed in claim 9 , wherein the organic compound is a carbon-containing compound comprising at least one of nitrogen, fluorine, phosphorus and sulfur.

12 . The method as claimed in claim 10 , wherein the mill is a wet mill with zirconium balls; a size of each of the zirconium balls is 0.1 mm; a filling ratio of the zirconium balls is 90%, which is a ratio of a total volume of the zirconium balls to a mixing volume of the mill; and in the steps A and B, a mixing and the grinding time of the mill is 2~4 hours and a rotation speed of the mill is 2800 rpm±20%.

13 . The method as claimed in claim 1 , wherein in the step C, a ratio of a total weight of the ceramic particles and a total weight of the first carbon nanotubes and the graphene sheets is 99.5:0.5; a ratio of a total weight of the graphene sheets and a total weight of the first carbon nanotubes is 4:1; a ratio of a weight of the polyvinylpyrrolidone and a weight of the sodium dodecyl sulfate is 3:1; and a weight percentage of a solid material formed by the polyvinylpyrrolidone, the sodium dodecyl sulfate, the graphene sheets and the first carbon nanotubes in the second mixed slurry is 5 wt %~20 wt %.

14 . The method as claimed in claim 1 , wherein each of the graphene sheets is a few-layer graphene (FLG) comprising 2~10 graphene layers; a size of each of the graphene sheets is less than 500 nm; and each of the first carbon nanotubes has a length less than 1 μm.

15 . The method as claimed in claim 12 , wherein in the step D, the second mixed slurry and the first mixed slurry are mixed and grinded under the protection of the nitrogen atmosphere by using the mill at the same grinding time and the same rotation speed as in the step B.

16 . The method as claimed in claim 1 , wherein the sintering of the step F is performed by increasing the temperature of the sintering furnace to a first sintering temperature of 180° C. at a raising rate of 5° C./minute and holding the first sintering temperature for 1 hour, and then increasing the first sintering temperature to a second sintering temperature of 280° C. at the raising rate and holding the second sintering temperature for 3 hours, and then increasing the second sintering temperature to a third sintering temperature of 600° C. at the raising rate and holding the third sintering temperature for 4 hours.

17 . The method as claimed in claim 1 , wherein in each of the conductive particles, a radial thickness of the amorphous carbon layer is less than 10 nm; and a particle size of each of the corresponding lithium fluoride particles is less than 5 nm.

18 . The method as claimed in claim 1 , further comprising the following step of:

step G: placing the conductive particles and a plurality of second carbon nanotubes (CNT) into a dry mixer and then mixing the conductive particles and the second carbon nanotubes to form a plurality of composite particles by using the dry mixer; wherein each of the composite particles includes a corresponding conductive particle and a plurality of corresponding second carbon nanotubes wrapping on an outer side of the corresponding conductive particle.

19 . The method as claimed in claim 18 , wherein each of the composite particles has a length of 1~3 μm; and in each of the composite particles, a ratio of a total weight of the corresponding second carbon nanotubes and a weight of the corresponding conductive particle is 1:99 to 0.2:99.8.