Negative active material for lithium secondary battery and lithium secondary battery including the same
A negative active material for a lithium secondary battery and a lithium secondary battery including the same are provided. The negative active material may be a silicon (Si)-based alloy negative active material. In some embodiments, the Si-based alloy negative active material may include Si, iron (Fe), copper (Cu), and aluminum (Al), and may have a Si single phase and a first alloy phase, the first alloy phase being represented by a formula of Al x Cu y , where x<y. In some embodiments, the Si-based alloy negative active material may include Si, Fe, and Cu, and may include a Si single phase, a first alloy phase, and a second alloy phase, the first alloy phase being represented by a formula of Cu 15 Si 4 , and the second alloy phase being represented by a formula of Cu 3 Fe 17 .
1. A negative active material for a lithium secondary battery, comprising:
a silicon (Si)-based alloy negative active material comprising Si, iron (Fe), copper (Cu), and aluminum (Al);
the Si-based alloy negative active material having a Si single phase and a first alloy phase, the first alloy phase being represented by a formula of Al x Cu y , where x<y.
2. The negative active material of claim 1 , wherein Al x Cu y comprises Al 4 Cu 9 .
3. The negative active material of claim 1 , wherein the Si-based alloy negative active material further has a second alloy phase, the second alloy phase being composed of Si and Fe or Si and Cu.
4. The negative active material of claim 3 , wherein the second alloy phase comprises at least one alloy phase represented by a formula selected from Cu 15 Si 4 and Fe 2 Si.
5. The negative active material of claim 1 , wherein an amount of the Fe ranges from about 5 atom % to about 20 atom % based on 100 atom % of the Si-based alloy negative active material.
6. The negative active material of claim 1 , wherein an amount of the Cu ranges from about 3 atom % to about 15 atom % based on 100 atom % of the Si-based alloy negative active material.
7. The negative active material of claim 1 , wherein an amount of the Al ranges from about 2 atom % to about 5 atom % based on 100 atom % of the Si-based alloy negative active material.
8. The negative active material of claim 1 , wherein an amount of the Si ranges from about 60 atom % to about 90 atom % based on 100 atom % of the Si-based alloy negative active material.
9. The negative active material of claim 1 , wherein the Si-based alloy negative active material has a capacity per volume of about 900 mAh/cc or more.
10. The negative active material of claim 1 , wherein the Si single phase comprises Si active particles of an average particle size of about 45 nm to about 60 nm.
11. A lithium secondary battery comprising:
a negative electrode comprising the negative active material according to claim 1 ;
a positive electrode; and
an electrolyte between the negative electrode and the positive electrode.