Complex particles for negative electrode active material and negative electrode for all-solid type battery comprising the same
Complex particles for a negative electrode active material according to the present disclosure have no problem with reduced capacity and output by virtue of sufficient electrochemical reaction sites between a solid electrolyte and an electrode active material. The complex particles according to the present disclosure include carbon particles of a carbon material such as flaky graphite, which are spherical in shape by shape modification, and a solid electrolyte and a conductive material filled between the particles, and thus have the increased contact area between the active material and the solid electrolyte increases, and ion conduction and electron conduction paths extended and maintained to the inside of the active material particles.
1. Complex particles for a negative electrode active material, comprising:
graphite particles of a granulated graphite material, and
a mixture including a solid electrolyte and a conductive material,
wherein the granulated graphite material is derived from any one of natural graphite or artificial graphite,
gaps within the granulated graphite material inside of the graphite particles are filled with the mixture, and an outer surface of the graphite particles is coated with the mixture in whole or at least in part, and
the granulated graphite material is included in an amount ranging from 70 weight % to 95 weight % based on 100 weight % of the complex particles.
2. The complex particles for a negative electrode active material according to claim 1 , wherein the complex particles have a particle diameter of 5 μm to 50 μm.
3. The complex particles for a negative electrode active material according to claim 1 , wherein the natural graphite is at least one highly crystalline natural graphite selected from platy, flaky, wavy, elliptical or whisker-shaped natural graphite.
4. The complex particles for a negative electrode active material according to claim 1 , wherein the solid electrolyte is included in an amount of 3 weight % to 50 weight % based on 100 weight % of the complex particles.
5. The complex particles for a negative electrode active material according to claim 1 , wherein the solid electrolyte includes a sulfide-based solid electrolyte.
6. The complex particles for a negative electrode active material according to claim 1 , wherein the conductive material includes one selected from graphite, carbon black, a conductive fiber, metal powder, potassium titanate, conductive whisker, conductive metal oxide, a polyphenylene derivative, or a mixture thereof.
7. A method for preparing the complex particles for a negative electrode active material according to claim 1 , comprising:
mixing a graphite material, a conductive material and a solid electrolyte to form a mixed composition, and
performing a spherical granulation process on the mixed composition by applying an external mechanical force to obtain the complex particles into which the graphite material, the conductive material and the solid electrolyte are integrally formed.
8. The method for preparing the complex particles according to claim 7 , wherein the granulation process is performed using one selected from a pulverizer; a granulator; a mixer selected from a dispersion kneader or two-roll; or a compression and shear processing machine selected from Mechano Micros, an extruder, a ball mill, a planetary mill, Mechano Fusion system, Nobilta, Hybridization System or a rotary ball mill or their combination.
9. The method for preparing complex particles according to claim 7 , wherein the mixed composition comprises 49 weight % to 95 weight % of the graphite material, 3 weight % to 50 weight % of the solid electrolyte, and 1 weight % to 10 weight % of the conductive material, based on 100 weight % of the mixed composition.
10. An all-solid type battery, comprising
a negative electrode, a positive electrode and a solid electrolyte film interposed between the negative electrode and the positive electrode,
wherein the negative electrode comprises the complex particles for a negative electrode active material according to claim 1 .
11. The complex particles for a negative electrode active material according to claim 1 , wherein the conductive material is included in an amount of 1 weight % to 10 weight % based on 100 weight % of the complex particles.
12. The complex particles for a negative electrode active material according to claim 1 , wherein the artificial graphite includes at least one of mosaic cokes-based artificial graphite or needle cokes-based artificial graphite.
13. The complex particles for a negative electrode active material according to claim 1 , wherein the solid electrolyte includes an ion conductive solid electrolyte material, a polymer solid electrolyte, an inorganic solid electrolyte, or a mixture thereof.