Anode for secondary battery
View Patent ↗Disclosed is an anode for secondary batteries comprising a combination of an anode active material having a relatively low charge/discharge voltage and a relatively low hardness (A) and an anode active material having a relatively high charge/discharge voltage and a relatively high hardness (B), wherein the anode active material (A) is surface-coated with carbon having a high hardness or a composite thereof, and a particle size of the anode active material (B) is smaller than a size of a space formed by the anode active materials (A) arranged in a four-coordination. The anode provides an electrode that prevents lithium precipitation caused by overvoltage, improves ionic conductivity as well as electric conductivity and exhibits superior capacity.
1. An anode for secondary batteries comprising a combination of an anode active material having a relatively low charge/discharge voltage and a relatively low hardness (A) and an anode active material having a relatively high charge/discharge voltage and a relatively high hardness (B),
wherein the anode active material (A) is surface-coated with carbon having a high hardness or a composite thereof, and a particle size of the anode active material (B) is smaller than a size of a space formed by the anode active materials (A) arranged in a four-coordination,
wherein the anode active material (B) is a carbon-based active material, and
wherein the anode active material (B) is positioned in a space provided between the anode active materials (A) arranged in a four-coordination.
2. The anode according to claim 1 , wherein the anode active materials (A) and (B) satisfy the following equation:
r≦R* 0.225
wherein R is a particle radius of an anode active material (A) and r is a particle radius of an anode active material (B).
3. The anode according to claim 1 , wherein the anode active material (A) has a charge/discharge voltage at 0.05 to 0.2V and the anode active material (B) has a charge/discharge voltage at 0.2 to 0.5V.
4. The anode according to claim 1 , wherein the hardness of the anode active material (B) is 1.2 to 5 times that of the anode active material (A).
5. The anode according to claim 1 , wherein the anode active material (A) is a graphite-based active material.
6. The anode according to claim 1 , wherein the anode active material (B) is present in an amount of more than 0% through less than 30%, with respect to the total weight of the active material.
7. An anode for secondary batteries comprising a combination of two types of anode active materials that have different charge/discharge voltages and different hardness, wherein, of the anode active materials, an anode active material having a relatively low hardness (A) is surface-coated with a material having 0.9 to 1.1 times the hardness of an anode active material having a relatively high hardness (B), and a particle size of the anode active material (B) is smaller than a size of a space formed by the anode active materials (A) arranged in a four-coordination,
wherein the anode active material (B) is a carbon-based active material, and
wherein the anode active material (B) is positioned in a space provided between the anode active materials (A) arranged in a four-coordination.
8. The anode according to claim 7 , wherein the material coated on the anode active material (A) has the same hardness as the anode active material (B).
9. An anode for secondary batteries comprising a combination of two types of anode active materials that have different charge/discharge voltages and different hardness, wherein, of the anode active materials, an anode active material having a relatively low hardness (A) is surface-coated with carbon or a composite thereof, and a particle size of an anode active material having a relatively high hardness (B) is (2 1/2 −1) times or less that of the anode active material (A),
wherein the anode active material (B) is a carbon-based active material, and
wherein the anode active material (B) is positioned in a space provided between the anode active materials (A) arranged in a four-coordination.
10. An anode for secondary batteries comprising a combination of two types of anode active materials that have different charge/discharge voltages and different hardness, wherein, of the anode active materials, an anode active material having a relatively low hardness (A) is surface-coated with a material having 0.9 to 1.1 times the hardness of an anode active material having a relatively high hardness (B), and a particle size of the anode active material (B) is (2 1/2 −1)-times or less that of the anode active material (A),
wherein the anode active material (B) is a carbon-based active material, and
wherein the anode active material (B) is positioned in a space provided between the anode active materials (A) arranged in a four-coordination.
11. A lithium secondary battery comprising the anode according to claim 1 .
12. A middle- or large-sized battery pack comprising the lithium secondary battery according to claim 11 as a unit battery.
13. A lithium secondary battery comprising the anode according to claim 7 .
14. A lithium secondary battery comprising the anode according to claim 9 .
15. A lithium secondary battery comprising the anode according to claim 10 .