Stepped electrode assembly including stepped unit cell

Abstract

There is provided a stepped electrode assembly including: a first electrode stack including at least one first unit cell, the first unit cell including at least one positive electrode and at least one negative electrode having the same area and being alternately stacked in a vertical direction with a separator disposed therebetween; and a second unit cell including at least one positive electrode and at least one negative electrode that are alternately stacked in the vertical direction with a separator disposed therebetween, the second unit cell disposed on a side of the first electrode stack with a separator disposed therebetween, wherein the second unit cell includes a first area electrode having the same area as an electrode area of the first electrode stack and a second area electrode having an area different from the area of the first area electrode, wherein the second unit cell is a stepped unit cell including a stepped portion formed by an area difference between the first and second area electrodes.

1 . A stepped electrode assembly comprising:
 a first electrode stack comprising at least one first unit cell, the first unit cell comprising at least one positive electrode and at least one negative electrode having the same area and being alternately stacked in a vertical direction with a separator disposed therebetween; and   a second unit cell comprising at least one positive electrode and at least one negative electrode that are alternately stacked in the vertical direction with a separator disposed therebetween, the second unit cell disposed on a side of the first electrode stack with a separator disposed therebetween,   wherein the second unit cell comprises a first area electrode having the same area as an electrode area of the first electrode stack and a second area electrode having an area different from the area of the first area electrode,   wherein the second unit cell is a stepped unit cell comprising a stepped portion formed by an area difference between the first and second area electrodes.   
     
     
         2 . The electrode assembly of  claim 1 , wherein the first and second area electrodes of the stepped unit cell face each other, and one of the first and second area electrodes having a comparatively large area is a negative electrode. 
     
     
         3 . The electrode assembly of  claim 1 , wherein the stepped unit cell is an A-type bi-cell comprising positive electrodes on both sides thereof and a negative electrode disposed therebetween, or a C-type bi-cell comprising negative electrodes on both sides thereof and a positive electrode disposed therebetween. 
     
     
         4 . The electrode assembly of  claim 3 , wherein the stepped unit cell is a stacked type unit cell or a stacked and folded type unit cell. 
     
     
         5 . The electrode assembly of  claim 2 , wherein a second electrode stack comprising electrodes having the same area as the area of the second area electrode of the stepped unit cell is disposed on the second area electrode of the stepped unit cell with a separator disposed therebetween, and the second area electrode and an electrode of the second electrode stack facing the second area electrode have different polarities. 
     
     
         6 . The electrode assembly of  claim 2 , wherein a second electrode stack comprising electrodes having equal areas different from the area of the second area electrode of the stepped unit cell is disposed on the second area electrode of the stepped unit cell with a separator disposed therebetween, and the second area electrode and an electrode of the second electrode stack facing the second area electrode have different polarities. 
     
     
         7 . The electrode assembly of  claim 6 , wherein a larger of the second area electrode and the electrode of the second electrode stack facing the second area electrode is a negative electrode. 
     
     
         8 . The electrode assembly of  claim 2 , wherein a second stepped unit cell is disposed on the second area electrode of the stepped unit cell with a separator disposed therebetween, and an electrode of the second stepped unit cell facing the second area electrode of the stepped unit cell has the same area as the second area electrode but a polarity different from that of the second area electrode. 
     
     
         9 . The electrode assembly of  claim 8 , wherein a comparatively large electrode of the second stepped unit cell is a negative electrode. 
     
     
         10 . The electrode assembly of  claim 2 , wherein a second stepped unit cell is disposed on the second area electrode of the stepped unit cell with a separator disposed therebetween, and an electrode of the second stepped unit cell facing the second area electrode of the stepped unit cell has an area and polarity different from those of the second area electrode. 
     
     
         11 . The electrode assembly of  claim 10 , wherein a larger of the second area electrode and the electrode of the second unit cell facing the second area electrode is a negative electrode, and a comparatively large electrode of the second stepped unit cell is a negative electrode. 
     
     
         12 . The electrode assembly of  claim 1 , wherein the electrode assembly is a stacked type electrode assembly or a stacked and folded type electrode assembly. 
     
     
         13 . The electrode assembly of  claim 1 , wherein each of outermost electrodes disposed on both sides of the electrode assembly is independently a negative electrode or a positive electrode. 
     
     
         14 . The electrode assembly of  claim 13 , wherein at least one of the outermost electrodes is a one-side-coated electrode. 
     
     
         15 . A secondary battery comprising the electrode assembly of  claim 1 . 
     
     
         16 . The secondary battery of  claim 15 , wherein the electrode assembly is disposed in a battery case. 
     
     
         17 . The secondary battery of  claim 16 , wherein the battery case is a pouch type case. 
     
     
         18 . The secondary battery of  claim 15 , wherein the secondary battery is a lithium ion secondary battery or a lithium ion polymer secondary battery. 
     
     
         19 . A battery pack comprising at least two secondary batteries as claimed in  claim 15 . 
     
     
         20 . A device comprising at least one secondary battery of  claim 15 . 
     
     
         21 . (canceled)