Negative electrode active material and secondary battery including the same
The present disclosure relates to a negative electrode active material and a secondary battery including the same, and in particular, provides a negative electrode active material particle including a core including a carbon-based active material, and a shell surrounding the core and including a polymer, wherein silicon-based active material particles are embedded in the shell, and at least a part of the silicon-based active material particles is exposed to a surface of the shell.
1. A negative electrode active material particle comprising:
a core comprising a carbon-based active material; and
a shell comprising a polymer coating on the core,
wherein silicon-based active material particles are embedded in the polymer coating,
wherein at least a part of the silicon-based active material particles are protruding from an outer surface of the shell, and
wherein all the silicon-based active material particles are not in contact with the carbon-based active material.
2. The negative electrode active material particle of claim 1 , wherein the polymer is a polymer having a π-bond.
3. The negative electrode active material particle of claim 1 , wherein the polymer is one or more types selected from the group consisting of poly(1-pyrenemethyl methacrylate) which is a homopolymer of pyrene, poly(1-pyrenemethyl methacrylate-co-triethylene oxide methyl ether methacrylate) which is a copolymer of pyrene, a polymer changing the pyrene side chain of the homopolymer or the copolymer of pyrene to anthracene, polyparaphenylene, polyaniline, poly(9,9-dioctylfluorene-co-fluorenone-co-methylbenzoic ester), and polyacetylene having a conjugation bond.
4. The negative electrode active material particle of claim 1 , wherein the carbon-based active material is one or more types selected from the group consisting of natural graphite, artificial graphite, hard carbon and soft carbon.
5. The negative electrode active material particle of claim 1 , wherein the carbon-based active material, the silicon-based active material and the polymer are included in a weight ratio of 65 to 93:5 to 20:2 to 15.
6. The negative electrode active material particle of claim 1 , wherein the silicon-based active material particles have an average diameter (D 50 ) of 10 nm to 150 nm.
7. The negative electrode active material particle of claim 1 , wherein the shell has a thickness of 20 nm to 100 nm.
8. A secondary battery comprising:
a negative electrode coated with a negative electrode mixture including the negative electrode active material particle of claim 1 ;
a positive electrode; and
a liquid electrolyte.
9. A battery module comprising the secondary battery of claim 8 as a unit cell.
10. A battery pack comprising the battery module of claim 9 , and used as a power supply of a device.
11. The battery pack of claim 10 , wherein the device is selected from the group consisting of electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles and systems for power storage.
12. The negative electrode active material particle of claim 1 , wherein the silicon-based active material particles are only attached to a surface of the carbon-based active material using the polymer.
13. A method for preparing the negative electrode active material particle according to claim 1 , comprising:
forming preliminary particles by coating a polymer on a core comprising a carbon-based active material (Step 1); and
preparing a solution including the preliminary particles, the polymer and silicon-based active material particles, and then spray drying the result to form a shell in which the silicon-based active material particles are embedded in the polymer coating (Step 2),
wherein at least a part of the silicon-based active material particles are protruding from an outer surface of the shell, and
wherein all the silicon-based active material particles are not in contact with the carbon-based active material.