Core-shell type anode active material for lithium secondary battery, method for preparing the same and lithium secondary battery comprising the same
The present invention relates to a core-shell type anode active material for a lithium secondary battery, a method of preparing the same, and a lithium secondary battery comprising the same. The anode active material for a lithium secondary battery according to the present invention comprises a carbon based material core portion; and a shell portion formed outside of the carbon based material core portion by coating the carbon based material core portion with a spinel-type lithium titanium oxide. The anode active material for a lithium secondary battery according to the present invention has the metal oxide shell portion, and thus has the improved conductivity, a high output density, and consequently excellent electrical characteristics.
1. An anode active material for a lithium secondary battery, comprising:
a carbon based material core portion; and
a shell portion formed outside of the carbon based material core portion by dry coating the carbon based material core portion with a spinel-type lithium titanium oxide,
wherein the spinel-type lithium titanium oxide has an average particle size of 30 to 800 nm, and
wherein the weight ratio of the carbon based material core portion to the spinel-type lithium titanium oxide shell portion is adjusted such that the carbon-based material: the spinel-type lithium titanium oxide=1:0.0055−0.0200.
2. The anode active material for a lithium secondary battery according to claim 1 ,
wherein the carbon based material for forming the core portion is any one selected from the group consisting of a soft carbon, a hard carbon, a natural graphite, Kish graphite, a pyrolytic carbon, a mesophase pitch based carbon fiber, meso-carbon microbeads, mesophase pitches, and petroleum or coal tar pitch derived cokes, or mixtures thereof.
3. A method for preparing an anode active material for a lithium secondary battery according to claim 1 , comprising:
(S1) preparing a carbon based material for forming a core portion; and
(S2) dry coating the core portion with a spinel-type lithium titanium oxide to form a shell portion outside of the core portion.
4. The method for preparing an anode active material for a lithium secondary battery according to claim 3 , further comprising:
heating the resultant product of the step (S2).
5. The method for preparing an anode active material for a lithium secondary battery according to claim 4 ,
wherein the heating is performed at 450 to 500° C. for 1 to 4 hours.
6. An anode of a lithium secondary battery, comprising:
an anode collector; and
an anode active material layer including an anode active material, a binder and a conductive material, and formed on at least one surface of a anode collector, wherein the anode active material is defined in any one of claims 1 to 2 .
7. A lithium secondary battery comprising:
a cathode;
an anode; and
a separator interposed between the cathode and the anode, wherein the anode is defined in claim 6 .