Stack-folding type electrode assembly and method of manufacturing the same
View Patent ↗The stack-folding type electrode assembly according to the present disclosure is an electrode assembly including a plurality of stack type unit cells which is stacked on one another with a continuous folding separator sheet interposed between each of the stacked unit cells, wherein the unit cells has a combination of at least two quad cells of a positive electrode/separator/negative electrode/separator/positive electrode/separator/negative electrode structure, and one C-type bicell of a negative electrode/separator/positive electrode/separator/negative electrode structure, and unit cells disposed above and below a central part or a winding start point have an asymmetrical structure each other with the quad cell disposed at the central part, or unit cells disposed above and below a central part or a winding start point have a symmetrical structure each other with the C-type bicell disposed at the central part.
1. An electrode assembly comprising a plurality of stack type unit cells which is stacked on one another with a continuous folding separator sheet interposed between each of the stacked unit cells,
wherein the unit cells comprise a combination of at least two quad cells of a positive electrode/separator/negative electrode/separator/positive electrode/separator/negative electrode structure, and one bicell of a negative electrode/separator/positive electrode/separator/negative electrode structure, and
unit cells, disposed above and below a central part or a winding start point, have an asymmetrical structure each other with the quad cell disposed at the central part, or unit cells, disposed above and below a central part or a winding start point, have a symmetrical structure each other with the bicell disposed at the central part.
2. The electrode assembly according to claim 1 , wherein the electrode assembly has a symmetrical structure of the unit cells disposed above and below the central part with the bicell disposed at the central part or a winding start point, and
the quad cells respectively disposed above and below the central bicell have an electrode direction which is symmetrical to each other.
3. The electrode assembly according to claim 1 , wherein the negative electrode is disposed at an outermost of the electrode assembly.
4. The electrode assembly according to claim 1 , wherein the folding separator sheet has a unit length sufficient to surround the unit cells, and is folded inwards each unit length to continuously surround the unit cells starting from a central unit cell to an outermost unit cell.
5. The electrode assembly according to claim 1 , wherein the folding separator sheet is an asymmetrical separator having different properties on both surfaces.
6. The electrode assembly according to claim 5 , wherein the folding separator sheet comprises:
a separator fabric;
a coating layer formed on one surface of the separator fabric, the coating layer containing an inorganic material for a negative electrode and a binder; and
a coating layer formed on the other surface of the separator fabric, the coating layer containing an inorganic material for a positive electrode and a binder, and
the negative electrodes of the bicell and the quad cells are disposed on the coating layer containing an inorganic material for a negative electrode and a binder, and the positive electrodes of the bicell and the quad cells are disposed on the coating layer containing an inorganic material for a positive electrode and a binder.
7. The electrode assembly according to claim 5 , wherein the folding separator sheet has a stack structure of a first separator and a second separator, and the negative electrodes of the bicell and the quad cells are disposed on any one of the first separator and the second separator, and the positive electrodes of the bicell and the quad cells are disposed on the other.
8. A secondary battery comprising an electrode assembly according to claim 1 .
9. A method of manufacturing an electrode assembly defined in claim 1 , the method comprising:
disposing a central unit cell at one end of a folding separator sheet, and continuously disposing unit cells at a predetermined interval; and
winding the central unit cell with the folding separator sheet once, and folding the folding separator sheet toward an outside where the adjacent unit cell is disposed, to stack the unit cells.
10. The method of manufacturing an electrode assembly according to claim 9 , wherein a negative electrode is disposed at an outermost of the electrode assembly.
11. The method of manufacturing an electrode assembly according to claim 9 , wherein negative electrodes of the unit cells are disposed on the folding separator sheet.
12. The method of manufacturing an electrode assembly according to claim 9 , wherein the folding separator sheet is an asymmetrical separator having different properties on both surfaces.
13. The method of manufacturing an electrode assembly according to claim 12 , wherein the folding separator sheet comprises:
a separator fabric;
a coating layer formed on one surface of the separator fabric, the coating layer containing an inorganic material for a negative electrode and a binder; and
a coating layer formed on the other surface of the separator fabric, the coating layer containing an inorganic material for a positive electrode and a binder, and
winding is performed with the negative electrodes of the unit cells disposed on the coating layer containing an inorganic material for a negative electrode and a binder.
14. The method of manufacturing an electrode assembly according to claim 12 , wherein the folding separator sheet has a stack structure of a first separator and a second separator, and winding is performed with the negative electrodes of the unit cells disposed on any one of the first separator and the second separator.
15. A method of manufacturing an electrode assembly, the electrode assembly comprising a plurality of stack type unit cells which is stacked on one another with a continuous folding separator sheet interposed between each of the stacked unit cells, the unit cells comprising a combination of at least two quad cells of a positive electrode/separator/negative electrode/separator/positive electrode/separator/negative electrode structure, and one C type bicell of a negative electrode/separator/positive electrode/separator/negative electrode structure, the electrode assembly having an asymmetrical structure of the unit cells disposed above and below a central part with the quad cell disposed at the central part or a winding start point,
the method comprising:
a cell design step of increasing a number of quad cells by one to increase a number of electrodes by four, on the basis of an electrode assembly comprising two quad cells and one bicell.
16. The method of manufacturing an electrode assembly according to claim 15 , wherein the bicell is inserted at an outermost of the electrode assembly, immediately above or below a center where the winding starts, or in the middle of the stack.