An electrode assembly comprising: a first electrode plate having a plurality of first electrode active material layers and a plurality of first electrode uncoated portions alternately positioned; a second electrode plate having a second electrode active material layer and a second electrode uncoated portion ; a separator between the first electrode plate and the second electrode plate ; and a ceramic layer on the first electrode uncoated portions and having a smaller thickness than the first electrode active material layers ; wherein the electrode assembly comprises planar portions, where the first electrode plate and the second electrode plate are planarly wound, and round portions, where the first electrode plate and the second electrode plate are curved to then be wound, the first electrode uncoated portions being positioned on the round portions; and wherein the first electrode active material layers have an equal length and the first electrode uncoated portions have gradually increasing lengths from a winding start portion to a winding end portion, or the first electrode uncoated portions have an equal length and the first electrode active material layers have gradually increasing lengths from a winding start portion to a winding end portion, wherein the first electrode active material layer comprises a high coating portion having a relatively large height at a coating start portion of the first electrode active material layer, and a low coating portion having a relatively small height at a coating end portion of the first electrode active material layer, and wherein the ceramic layer covers the high coating portion and the low coating portion . a first electrode plate having a plurality of first electrode active material layers and a plurality of first electrode uncoated portions alternately positioned; a second electrode plate having a second electrode active material layer and a second electrode uncoated portion ; a separator between the first electrode plate and the second electrode plate ; and a ceramic layer on the first electrode uncoated portions and having a smaller thickness than the first electrode active material layers ; wherein the electrode assembly comprises planar portions, where the first electrode plate and the second electrode plate are planarly wound, and round portions, where the first electrode plate and the second electrode plate are curved to then be wound, the first electrode uncoated portions being positioned on the round portions; and wherein the first electrode active material layers have an equal length and the first electrode uncoated portions have gradually increasing lengths from a winding start portion to a winding end portion, or the first electrode uncoated portions have an equal length and the first electrode active material layers have gradually increasing lengths from a winding start portion to a winding end portion, wherein the first electrode active material layer comprises a high coating portion having a relatively large height at a coating start portion of the first electrode active material layer, and a low coating portion having a relatively small height at a coating end portion of the first electrode active material layer, and wherein the ceramic layer covers the high coating portion and the low coating portion . <EOS>