JELLY-ROLL OF IMPROVED PRODUCTIVITY AND BATTERY CELL COMPRISING THE SAME
Disclosed herein is a jelly roll for a secondary battery configured by winding a cathode sheet, a separator, and an anode sheet, wherein electrode tabs are connected to uncoated portions of the electrode sheets, to which electrode active materials are not applied, by welding, and each of the electrode tabs is configured to have an embossed structure protruding toward the uncoated portion to improve weldability.
1 . A jelly roll for a secondary battery configured by winding a cathode sheet, a separator, and an anode sheet, wherein electrode tabs are connected to uncoated portions of the electrode sheets, to which electrode active materials are not applied, by welding, and each of the electrode tabs is configured to have an embossed structure protruding toward the uncoated portion to improve weldability.
2 . The jelly roll according to claim 1 , wherein the electrode tabs are made of aluminum or nickel.
3 . The jelly roll according to claim 1 , wherein the embossed structure comprises a plurality of micro protrusions configured to have a structure having protruding parts formed at one side thereof facing the uncoated portion and depressed parts formed at the other side thereof so as to correspond to the protrusions.
4 . The jelly roll according to claim 3 , wherein each of the micro protrusions has a protruding height of 50 to 500 microns.
5 . The jelly roll according to claim 3 , wherein each of the micro protrusions has a protruding height of 100 to 150 microns.
6 . The jelly roll according to claim 1 , wherein the electrode tabs are connected to the uncoated portions by ultrasonic welding.
7 . The jelly roll according to claim 6 , wherein the ultrasonic welding is performed by a welding device comprising horn tips arranged at intervals corresponding to the micro protrusions of the embossed structure.
8 . The jelly roll according to claim 7 , wherein the ultrasonic welding is performed by applying ultrasonic waves in a state in which the horn tips are located in the depressed parts of the respective micro protrusions.
9 . A method of manufacturing a jelly roll according to claim 1 , the method comprising:
(a) winding a cathode sheet and an anode sheet in a state in which a separator is disposed between the cathode sheet and the anode sheet;
(b) positioning electrode tabs each having an embossed structure formed at a surface thereof on uncoated portions of the cathode sheet and the anode sheet so that protruding parts of the embossed structure face a corresponding one of the uncoated portions; and
(c) positioning horn tips of a welding device in depressed parts of the embossed structure of each of the electrode tabs and applying ultrasonic waves to the depressed parts.
10 . A battery cell comprising a jelly roll according to claim 1 , wherein the jelly roll is mounted in a battery case.
11 . The battery cell according to claim 10 , wherein the battery cell is a cylindrical battery or a prismatic battery.
12 . A battery module comprising a plurality of battery cells according to claim 11 as unit cells.