An electrochemical cell, comprising: a plurality of positive electrode sheets having current collecting tabs which are portions of the positive electrode sheets that extend outwardly; a plurality of negative electrode sheets having current collecting tabs which are portions of the negative electrode sheets that outwardly, the current collecting tabs of the positive electrode sheets have a width that is different than a width of the current collecting tabs of the negative electrode sheets, and the positive and negative electrode sheets being layered in the cell; a positive extension tab extended from the current collecting tabs of the positive electrode sheets; a negative extension tab extended from the current collecting tabs of the negative electrode sheets; the positive and negative extension tabs respectively having a length, width and thickness; wherein a cross sectional area of the positive extension tab is different than a cross sectional area of the negative extension tab, a width of the positive extension tab is the same as the width of the current collecting tabs of the positive electrode sheets, and a width of the negative extension tab is the same as the width of the current collecting tabs of the negative electrode sheets, wherein the length and the width of the positive extension tab are each at least 10 times the thickness of the positive extension tab, and the length and the width of the negative extension tab are each at least 10 times the thickness of the negative extension tab, and wherein the cross sectional area of the positive extension tab provides a temperature gradient in the positive extension tab during discharge, and the cross sectional area of the negative extension tab provides a temperature gradient in the negative extension tab during discharge, the temperature gradient of the positive extension tab corresponds uniformly to the temperature gradient of the negative extension tab. a plurality of positive electrode sheets having current collecting tabs which are portions of the positive electrode sheets that extend outwardly; a plurality of negative electrode sheets having current collecting tabs which are portions of the negative electrode sheets that outwardly, the current collecting tabs of the positive electrode sheets have a width that is different than a width of the current collecting tabs of the negative electrode sheets, and the positive and negative electrode sheets being layered in the cell; a positive extension tab extended from the current collecting tabs of the positive electrode sheets; a negative extension tab extended from the current collecting tabs of the negative electrode sheets; the positive and negative extension tabs respectively having a length, width and thickness; wherein a cross sectional area of the positive extension tab is different than a cross sectional area of the negative extension tab, a width of the positive extension tab is the same as the width of the current collecting tabs of the positive electrode sheets, and a width of the negative extension tab is the same as the width of the current collecting tabs of the negative electrode sheets, wherein the length and the width of the positive extension tab are each at least 10 times the thickness of the positive extension tab, and the length and the width of the negative extension tab are each at least 10 times the thickness of the negative extension tab, and wherein the cross sectional area of the positive extension tab provides a temperature gradient in the positive extension tab during discharge, and the cross sectional area of the negative extension tab provides a temperature gradient in the negative extension tab during discharge, the temperature gradient of the positive extension tab corresponds uniformly to the temperature gradient of the negative extension tab.