Negative electrode and method for preparing negative electrode
A negative electrode according to one embodiment of the present invention comprises a current collector and a negative electrode active material layer disposed on the current collector, wherein the negative electrode active material layer includes a first particle and a second particle, the first particle includes a first core including artificial graphite; and a first shell disposed on the first core, said first shell including an oxide of the artificial graphite, wherein a sphericity of the first particle measured through a particle shape analyzer is from 0.94 to 0.98, the second particle is artificial graphite having sphericity measured through the particle shape analyzer of 0.70 to 0.92, and a weight ratio of the first particle and the second particle is from 1:1 to 1:9.
1. A negative electrode comprising:
a current collector; and
a negative electrode active material layer disposed on the current collector,
wherein the negative electrode active material layer includes first particles, second particles and third particles,
each first particle comprises a first core including artificial graphite; and a first shell disposed on the first core, said first shell including an oxide of the artificial graphite, a sphericity of each first particle measured through a particle shape analyzer is from 0.94 to 0.98,
each second particle is artificial graphite having a sphericity measured through the particle shape analyzer of 0.70 to 0.92,
each third particle comprises a second core including natural graphite; and a second shell disposed on the second core, said second shell including an oxide of the natural graphite, and each third particle having a sphericity measured through the particle shape analyzer from 0.94 to 0.98, and
a weight ratio of first particles to second particles is from 1:1 to 1:9.
2. The negative electrode of claim 1 , wherein the first particles have an average particle diameter (D 50 ) of 10 μm to 25 μm.
3. The negative electrode of claim 1 , wherein the first cores have an average particle diameter (D 50 ) of 10 μm to 20 μm.
4. The negative electrode of claim 1 , wherein each of the first shells have a thickness of 1 nm to 200 nm.
5. The negative electrode of claim 1 , wherein the first particles have a tap density of 0.95 g/cm 3 to 1.3 g/cm 3 ,
wherein the tap density is measured after tapping 1,000 times.
6. The negative electrode of claim 1 , wherein the second particles have an average particle diameter (D 50 ) of 10 μm to 25 μm.
7. The negative electrode of claim 1 , wherein an oxygen atom content is from 1200 mg/kg to 2500 mg/kg with respect to a total weight of the first particles.
8. The negative electrode of claim 1 , wherein a total weight of the first particles and the second particles is from 95% by weight to 99% by weight with respect to a total weight of the negative electrode active material layer.
9. The negative electrode of claim 1 , wherein a weight ratio of the first particles, the second particles and the third particles is 10-30:40-80:10-30.
10. The negative electrode of claim 1 , wherein the third particles have an average particle diameter (D 50 ) of 7 μm to 25 μm.
11. The negative electrode of claim 1 , wherein the second cores have an average particle diameter (D 50 ) of 5 μm to 25 μm.
12. The negative electrode of claim 1 , wherein each of the second shells have a thickness of 1 nm to 200 nm.
13. The negative electrode of claim 1 , wherein the third particles have a tap density of 1.0 g/cm 3 to 1.2 g/cm 3 ,
wherein the tap density is measured after tapping 1,000 times.
14. A method for preparing a negative electrode comprising:
preparing a negative electrode slurry (step 1); and
coating the negative electrode slurry on a current collector and then drying the result (step 2),
wherein the negative electrode slurry includes first particles, second particles, and third particles,
each first particle comprises a first core including artificial graphite; and a first shell disposed on the first core, said first shell including an oxide of the artificial graphite, a sphericity of each first particle measured through a particle shape analyzer is from 0.94 to 0.98,
each second particle is artificial graphite having a sphericity measured through the particle shape analyzer of 0.70 to 0.92,
each third particle comprises a second core including natural graphite; and a second shell disposed on the second core, said second shell including an oxide of the natural graphite, and each third particle having a sphericity measured through the particle shape analyzer from 0.94 to 0.98, and
a weight ratio of first particles to second particles is from 1:1 to 1:9.
15. The negative electrode of claim 1 , wherein each third particle has a sphericity measured through the particle shape analyzer from 0.96 to 0.97.