Electrode structure for secondary battery, method of manufacturing the same, and secondary battery comprising the same
An electrode for a secondary battery includes a current collector; and an active material structure on the current collector, the activate material structure including: at least one first high-density layer, and at least one second high-density layer, the at least one second high-density layer being further away from the current collector as compared to the at least one first high-density layer; and a low-density layer between the at least one first high-density layer and the at least one second high-density layer, wherein a thickness of the at least one second high-density layer is greater than a thickness of the at least one first high-density layer.
1. An electrode for a secondary battery, the electrode comprising:
a current collector; and
an active material structure on the current collector, the active material structure comprising
at least one first high-density layer, and
at least one second high-density layer, the at least one second high-density layer being further away from the current collector as compared to the at least one first high-density layer; and
a low-density layer between the at least one first high-density layer and the at least one second high-density layer,
wherein a thickness of the at least one second high-density layer is greater than a thickness of the at least one first high-density layer.
2. The electrode of claim 1 , wherein
a solid content of the at least one first high-density layer is about 90 volume percent to about 98 volume percent, based on a total volume of the at least one first high-density layer,
a solid content of the at least one second high-density layer is about 90 volume percent to about 98 volume percent, based on a total volume of the at least one second high-density layer, and
a solid content of the low-density layer is about 25 volume percent to about 50 volume percent, based on a total volume of the low density layer.
3. The electrode of claim 1 , wherein an outermost one of the at least one second high-density layer has a greatest thickness among each layer of the at least one first high-density layer, each layer of the at least one second high-density layer, and each layer of the low-density layer.
4. The electrode of claim 1 , wherein the at least one first high-density layer comprises a primary first high-density layer and a secondary first high-density layer,
the low-density layer comprises a first low-density layer between the primary first high-density layer and the secondary first high-density layer, and
the primary first high-density layer and the secondary first high-density layer have a same thickness or a different thickness.
5. The electrode of claim 4 , wherein a thickness ratio of a thickness of the primary first high-density layer or the secondary first high-density layer to a thickness of each layer of the at least one second high-density layer is greater than about 1:1 and less than or equal to about 1:5.
6. The electrode of claim 1 , wherein the at least one first high-density layer comprises a primary first high-density layer, a secondary first high-density layer, and a tertiary first high-density layer,
the low-density layer comprises a primary low-density layer between the primary first high-density layer and the secondary first high-density layer,
the low-density layer comprises a secondary low-density layer between the secondary first secondary first high-density layer and the tertiary first high-density layer, and
at least two of the primary first primary first high-density layer, the secondary first high-density layer, and the tertiary first high-density layer have a same thickness or a different thickness.
7. The electrode of claim 6 , wherein a thickness ratio of a thickness of the primary first high-density layer, the secondary first high-density layer, or the tertiary first high-density layer to a thickness of each layer of the at least one second high-density layer is greater than about 1:1 and less than or equal to about 1:5.
8. The electrode of claim 1 , wherein a thickness ratio of a total thickness of the at least one first high-density layer to a total thickness of the at least one second high-density layer is about 1.5:1 to about 1:6.
9. The electrode of claim 1 , wherein a thickness ratio of a thickness of each first high-density layer of the at least one first high-density layer to a thickness of the low-density layer is about 1:0.1 to about 1:0.3.
10. The electrode of claim 1 , wherein a thickness ratio of a thickness of each second high-density layer of the at least one second high-density layer to a thickness of each layer of the low-density layer is about 1:0.1 to about 1:0.3.
11. The electrode of claim 1 , wherein the low-density layer comprises a single layer or a plurality of layers, and
each low-density layer has a thickness of about 2 μm to about 5 μm.
12. The electrode of claim 1 , wherein the low-density layer comprises at least one of a solid electrolyte, a liquid electrolyte, or an ionic liquid.
13. The electrode of claim 1 , wherein the at least one first high-density layer and the at least one second high-density layer each independently has a porosity of about 1% to about 5%.
14. The electrode of claim 1 , wherein the low-density layer has a porosity of about 25% to about 50%.
15. The electrode of claim 1 , wherein each layer of the at least one first high-density layer has a thickness of about 8 μm to about 40 μm.
16. The electrode of claim 1 , wherein each layer of the at least one second high-density layer has a thickness of about 10 μm to about 40 μm.
17. The electrode of claim 1 , wherein the at least one second high-density layer comprises a primary second high-density layer and a secondary second high-density layer,
the low-density layer is between the primary second high-density layer and the secondary second high-density layer, and
the primary second high-density layer and the secondary second high-density layer have a same thickness or different thicknesses.
18. The electrode of claim 17 , wherein a thickness ratio of a thickness of the primary second high-density layer or the secondary second high-density layer to a thickness of each layer of the low-density layer is about 1:0.1 to about 1:0.3.
19. The electrode of claim 1 , wherein the at least one second high-density layer comprises a primary second high-density layer, a secondary second high-density layer, and a tertiary second high-density layer,
the low-density layer comprises a first low-density layer between the primary second high-density layer and the secondary second high-density layer, and a second low-density layer between the secondary second high-density layer and the tertiary second high-density layer, and
at least two of the primary second primary first high-density layer, the secondary second high-density layer, and the tertiary second high-density layer have a same thickness or different thicknesses.
20. The electrode of claim 19 , wherein a thickness ratio of a thickness of the primary second high-density layer, the secondary second high-density layer, or the tertiary second high-density layer to a thickness of each layer of the low-density layer is about 1:0.1 to about 1:0.3.
21. The electrode of claim 1 , wherein the active material structure has a plurality of channels extending in a thickness direction.
22. The electrode of claim 21 , wherein the plurality of channels comprise at least one of a solid electrolyte, an ionic liquid, or a liquid electrolyte.
23. The electrode of claim 1 , wherein the electrode is a sintered electrode having a relative density of about 85% to about 99%.
24. The electrode of claim 1 , wherein a thickness ratio of a thickness of each first high-density layer of the at least one first high-density layer to a thickness of each second high-density layer of the at least one second high-density layer is about 1:2 to about 1:4.
25. The electrode of claim 1 , wherein the active material structure has a plurality of channels extending in a thickness direction, and
a plurality of low-density layers separated by the plurality of channels, and
each layer of the plurality of low-density layers has a different composition.
26. A method of manufacturing an electrode for a secondary battery, the method comprising:
forming a structure by pressing a stack comprising
providing at least one first high-density layer, a low-density layer, and at least one second high-density layer;
disposing the low-density layer between the at least one first high-density layer and the at least one second high-density layer to form a stack;
pressing the stack to form a structure;
sintering the structure to manufacture an active material structure; and
disposing a current collector on the active material structure and proximate to the at least one first high-density layer to manufacture the electrode of claim 1 .
27. The method of claim 26 , further comprising, before the sintering, forming a plurality of channels extending in a thickness direction of the electrode.
28. The method of claim 26 , wherein the sintering comprises sintering at a temperature of about 1000° C. to about 1300° C.
29. A secondary battery comprising:
a first electrode;
a second electrode on the first electrode; and
a separator between the first electrode and the second electrode,
wherein at least one of the first electrode or the second electrode is the electrode of claim 1 .
30. The secondary battery of claim 29 , wherein the first electrode is a cathode, and the second electrode is an anode.
31. The secondary battery of claim 29 , wherein the secondary battery has a ratio of discharge capacity at 1C to a discharge capacity at 0.2C of about 90% to about 95%, an energy density of about 500 watt-hours per liter to about 605 watt-hours per liter, and a capacity retention after 400 charge-discharge cycles of about 88% to about 90%.
32. A cathode, comprising:
the electrode of claim 1 ,
wherein at least one of the first high-density layer, the second high-density layer, or the low-density layer comprises a cathode active material.