It has been demonstrated that small amounts of active lithium metal can be added to a lithium-ion (Li-ion) battery via the separator by using vacuum deposition techniques. Lithium films (4–8 μm) were deposited onto micro-porous polypropylene film that is used as the separator in Li-ion cells. We have demonstrated that the lithium electrochemically reacts with either electrode depending on the geometry of assembly. As a result, the intrinsic irreversible capacity of negative electrode can be compensated using volumetrically efficient lithium metal. Hence, Li-ion cells can be designed and constructed with significantly higher energy than those assembled with conventional techniques.