Electrode active material for secondary battery
View Patent ↗Disclosed herein is an electrode active material for a secondary battery, and more particularly to an electrode active material comprising a porous silicon oxide-based composite and the method for preparing a porous silicon oxide-based composite.
1. A secondary lithium battery comprising an electrode active material comprising a porous silicon oxide-based composite comprising porous silicon oxide particles having a carbon coating on a surface thereof and lithium dispersed therein, which is prepared by a method comprising: coating a surface of the porous silicon oxide particles with carbon, mixing the coated porous silicon oxide particles with a lithium precursor to prepare a mixture, and heat-treating the mixture at 500-1200° C.,
wherein the porous silicon oxide-based composite comprises a silicon phase, a SiO x (0<x<2) phase and a silicon dioxide phase,
wherein the lithium is present in an amount of 2-15 wt % based on the total weight of the porous silicon oxide-based composite,
wherein the lithium precursor is selected from the group consisting of LiOH·H 2 O, Li(OH)·H 2 O, LiCH 3 OO·2H 2 O, Li 2 SO 4 , Li 3 PO 4 , and salts thereof, and
wherein the secondary lithium battery has an initial efficiency of 77% to 95%.
2. The secondary lithium battery of claim 1 , wherein the carbon is present in an amount of 2-30 wt % based on the total weight of the porous silicon oxide-based composite.
3. The secondary lithium battery of claim 1 , wherein the silicon oxide in the porous silicon oxide-based composite is silicon monoxide.
4. The secondary lithium battery of claim 1 , wherein the porous silicon oxide-based composite has a BET specific surface area of 2-100 m 2 /g.
5. The secondary lithium battery of claim 1 , wherein the silicon dioxide phase is dispersed in the SiO x phase.
6. The secondary lithium battery of claim 1 , wherein the silicon dioxide phase is crystalline.
7. The secondary lithium battery of claim 1 , wherein a concentration of the silicon phase is higher towards a center portion than towards a center-periphery portion of the porous silicon oxide-based composite.
8. The secondary lithium battery of claim 1 , wherein a concentration of the silicon dioxide phase is higher towards a center-periphery portion than towards a center portion of the porous silicon oxide-based composite.
9. The secondary lithium battery of claim 1 , wherein the silicon phase and the silicon dioxide phase are formed by disproportionation of SiO x (0<x<2).
10. The secondary lithium battery of claim 1 , wherein the porous silicon oxide-based composite has a porosity of 5-90%.
11. The secondary lithium battery of claim 1 , wherein a concentration of the lithium dispersed in the porous silicon oxide-based composite is the highest at a portion near the carbon-coated surface and decreases toward a center of the porous silicon oxide-based composite.