Jelly-roll type electrode assembly pattern-coated with active material and secondary battery including the same

1. A method of manufacturing a jelly-roll electrode assembly pattern-coated with active materials, manufactured by winding and compressing a separator and an anode and a cathode arranged on both sides of the separator,

wherein the anode comprises an anode flat coated portion coated with an anode active material and an anode curved uncoated portion not coated with the anode active material, which are alternately formed, and

wherein the cathode comprises a cathode flat coated portion coated with a cathode active material and a cathode curved uncoated portion not coated with the cathode active material, which are alternately formed,

wherein the widths of the curved uncoated portion of the cathode and the anode are formed to be smaller than that of the electrode assembly curved portion, and inflection points of the curved portion of the electrode assembly are included in the curved uncoated portion of the cathode and the anode,

the method comprising any one of;

determining widths of an inner side and an outer side of the anode curved uncoated portion and the cathode curved uncoated portion to which widths of an inner side and an outer side of the anode curved uncoated portion satisfy following equations (1) and (2) respectively, and to which widths of an inner side and outer side of the cathode curved uncoated portion satisfy following equations (3) and (4) respectively, in order that a first radius curvature of the anode curved uncoated portion is smaller than a first radius curvature of the cathode curved uncoated portion; and

determining widths of an inner side and an outer side of the cathode curved uncoated portion and the anode curved uncoated portion to which widths of an inner side and an outer side of the cathode curved uncoated portion satisfy following equations (5) and (6) respectively, and to which widths of an inner side and an outer side of the anode curved uncoated portion satisfy following equations (7) and (8) respectively, in order that a first radius curvature of the cathode curved uncoated portion is smaller than a first radius curvature of the anode curved uncoated portion;

W ( I ) n anode <π{( Ts/ 2)+( n− 1)( Ts+Ta/ 2 +Tc/ 2)}  Equation (1)

wherein W(I)n designates a width of an inner side of an nth anode curved uncoated portion, Ts designates a thickness of the separator, Ta designates a thickness of the anode, Tc designates a thickness of the cathode, and n is an integer;

W ( II ) n anode <π{( Ts/ 2 +Ta )+( n− 1)( Ts+Ta/ 2 +Tc/ 2)}  Equation (2)

wherein W(II)n designates a width of an outer side of an nth anode curved uncoated portion, Ts designates a thickness of the separator, Ta designates a thickness of the anode, Tc designates a thickness of the cathode, and n is an integer;

W ( III ) n cathode <π{(3 Ts/ 2 +Ta )+( n− 1)( Ts+Ta/ 2 +Tc/ 2)}  Equation (3)

wherein W(III)n designates a width of an inner side of an nth cathode curved uncoated portion, Ts designates a thickness of the separator, Ta designates a thickness of the anode, Tc designates a thickness of the cathode, and n is an integer;

W ( IV ) n cathode <π{(3 Ts/ 2 +Ta+Tc )+( n− 1)( Ts+Ta/ 2 +Tc/ 2)}  Equation (4)

wherein W(IV)n designates a width of an outer side of the nth cathode curved uncoated portion, Ts designates the thickness of the separator, Ta designates a thickness of the anode, Tc designates a thickness of the cathode, and n is an integer;

W ( I ) n cathode <π{( Ts/ 2)+( n− 1)( Ts+Ta/ 2 +Tc/ 2)}  Equation (5)

wherein W(I)n designates a width of an inner side of an nth cathode curved uncoated portion, Ts designates a thickness of the separator, Ta designates a thickness of the cathode, Tc designates a thickness of the anode, and n is an integer;

W ( II ) n cathode <π{( Ts/ 2 +Ta )+( n− 1)( Ts+Ta/ 2 +Tc/ 2)}  Equation (6)

wherein W(II)n designates a width of an outer side of the nth cathode curved uncoated portion, Ts designates the thickness of the separator, Ta designates a thickness of the cathode, Tc designates a thickness of the anode, and n is an integer;

W ( III ) n anode <π{(3 Ts/ 2 +Ta )+( n− 1)( Ts+Ta/ 2 +Tc/ 2)}  Equation (7)

wherein W(III)n designates a width of an inner side of an nth anode curved uncoated portion, Ts designates a thickness of the separator, Ta designates a thickness of the cathode, Tc designates a thickness of the anode, and n is an integer;

W ( IV ) n anode <π{(3 Ts/ 2 +Ta+Tc )+( n− 1)( Ts+Ta/ 2 +Tc/ 2)}  Equation (8)

wherein W(IV)n designates a width of an outer side of the nth anode curved uncoated portion, Ts designates the thickness of the separator, Ta designates a thickness of the cathode, Tc designates a thickness of the anode, and n is an integer.

2. The method of manufacturing the jelly-roll electrode assembly of claim 1 , wherein the anode flat coated portions or the cathode flat coated portions have the same width as one another.

3. The method of manufacturing the jelly-roll electrode assembly of claim 1 , wherein the anode curved uncoated portion has widths increasing progressively from a first end to a last end of the anode in contact with a core for winding the electrode assembly.

4. The method of manufacturing the jelly-roll electrode assembly of claim 1 , wherein in the case that the first radius curvature of the anode curved uncoated portion is smaller than a first radius curvature of the cathode curved uncoated portion, the cathode curved uncoated portion has widths increasing progressively from a first end to a last end of the cathode in contact with a core for winding the electrode assembly.

5. The method of manufacturing the jelly-roll electrode assembly of claim 1 , wherein the cathode active material is lithium iron phosphate having an olivine crystal structure having a composition satisfying a following formula,

Li 1+a Fe 1-x M x (PO 4-b )X b   Formula (1)

wherein M is at least one selected from the group consisting Al, Mg, Ni, Co, Mn, Ti, Ga, Cu, V, Nb, Zr, Ce, In, Zn, and Y, X is at least one selected from the group consisting of F, S, and N, and −0.5≦a≦+0.5, 0≦x≦0.5, 0≦b≦0.1.

6. The method of manufacturing the jelly-roll electrode assembly of claim 5 , wherein lithium iron phosphate is LiFePO 4 .