To engineers of the iconic racing red Ferrari, weight is everything. The high performance of this legendary Italian sports car owes to careful consideration of how much weight each of its parts contributes to the whole. With the inevitable demand for a more environmentally friendly Ferrari, engineers took on the notoriously heavy rechargeable battery of a hybrid engine. For the Ferrari HY-KERS hybrid concept car introduced in 2010, they compensated for the weight of a lithium-ion battery pack by adding power, one horsepower for every kilogram of extra weight. However, with recent advancements in lithium-ion battery technology, such compensation may no longer be needed. Cathode reactants of traditional lithium-ion batteries are relatively heavy lithium metal oxides. To provide similar power at a fraction of the weight, lithium-oxygen or lithium-air technology replaces these heavy cathode reactants with lightweight oxygen pulled from the surrounding atmosphere.