An electronic device, including a housing that is metal or lined with an electrically conductive material, at least one electrical component, and a battery cell positioned in a cavity in the outer housing, the battery cell integrated into the electronic device. The battery cell includes a first current collector and an active cell core. The first current collector is the electrically conductive material of the outer housing of the electronic device and connects to the at least one electrical component. The active cell core includes a first active material in adjacent facing relation to and electrically coupled to the first current collector, a second active material; a separator positioned between the first active material and the second active material; and a second current collector electrically coupled with the second active material, wherein the second current collector connects to the at least one electrical component.