Knight and Day

After colliding with Roy Miller (Tom Cruise) twice in the airport departure terminal on the way home from Wichita to pick up car parts, June Havens (Cameron Diaz) is told she has been bumped to a later flight. C.I.A. Agent John Fitzgerald (Peter Sarsgaard), believing Havens is working with Miller, puts her back on the plane. Completely taken with Miller, Havens goes to the restroom to prep herself up. Meanwhile, Miller fights and kills everyone else on the plane, even the pilots, who were all agents sent by Fitzgerald. After Havens reemerges and gives him a kiss, Miller crash-lands the plane in a cornfield. He drugs a shocked and confused Havens, warning her about the agents who will come after her and that she is not safe with them.
Waking up at home, Havens struggles through a day fitting a bridesmaid's dress for her sister's wedding, and is shocked to learn her sister would like to sell their father's 1966 Pontiac GTO tri-power, which Havens had planned on finishing as a wedding present. Havens is then picked up by a group of intelligence agents, led by Fitzgerald. Miller arrives and, through a long gunfight on the highway, kills several agents and reclaims Havens. She flees at the first opportunity and contacts Rodney (Marc Blucas), a firefighter and former boyfriend. Believing Havens is merely stressed and is playing out a fantasy, Rodney takes her out and she tells him everything that has happened to her, though he still does not understand. Miller then arrives and pretends to take Havens hostage while holding everyone else at gunpoint, fleeing with her.
Miller explains that Havens is safer with him and she agrees to follow him as they go to pick up Simon Feck (Paul Dano), a genius inventor who has created a perpetual energy battery called the Zephyr. Traveling to Brooklyn, Miller and Havens discover that Feck has fled from the warehouse he was hiding in, leaving a clue for Miller about his location. They are then attacked by henchmen sent by Spanish arms dealer, Antonio Quintana (Jordi MollÃ ). After again being drugged, Havens drifts in and out of consciousness between their capture and escape from Quintana's men, and Miller brings her to an island that is off-the-grid, which Miller uses as a safe house. Accepting a call from her sister after leaving in frustration, Havens accidentally leads Quintana's men straight to the hideaway. They try to kill Miller and Havens with an unmanned aerial vehicle. Before they escape by helicopter, Havens is knocked-out by Miller since she is afraid of flying.
Miller reunites with Feck and they, with Havens, get on a train heading for Austria. Havens is attacked by Bernard (Falk Hentschel), an assassin sent by Quintana to retrieve the Zephyr and Feck, and kill Miller. But Miller and Havens fight him and he is killed by another train. Arriving at Salzburg, the three check into a hotel. Miller later leaves to meet with Naomi (Gal Gadot), Quintana's henchwoman, to make a deal. Havens follows him and listens to Miller's conversation, mistaking that he doesnât care for her. She is then picked up by Fitzgerald and C.I.A. Director Isabel George (Viola Davis), who reveal that Miller was using her at the airport to smuggle in the Zephyr when they bumped into each other and convince her that he doesn't love her. They also tell her that Miller is the traitor and plans to trade the battery with Quintana. Heartbroken, Havens allows the C.I.A. to find Miller back at the hotel. Miller escapes with the battery, but is seemingly shot on the rooftop and falls to his death in the river. Feck is taken into custody afterwards to Schwedelbach, Germany, though it is later revealed that Fitzgerald has been the real traitor all along and he captures Feck.
Returning home, Havens heads to an address she remembered from Miller's iPhone, where she finds his parents and learns that his real name is Matthew Knight. They believe their son, a former Army sergeant and Eagle Scout, is dead; but they are fabulously wealthy from winning lotteries and sweepstakes they don't remember entering. Leaving a message on her own answering machine that she has the Zephyr, she is captured by Quintana's men and taken to Sevilla, Spain. She is drugged with truth serum before being rescued by Miller, who was tracking Fitzgerald, who was delivering Feck to Quintana.
Chaos erupts throughout the streets and Quintana is killed by a bull stampede. At the docks, Miller saves Feck from a bullet wound after handing over the Zephyr in a small pouch. Feck later reveals that the battery is unstable and it explodes, killing Fitzgerald. Miller collapses from the gunshot and is hospitalized in Washington D.C.. George apologizes to Miller about him and Fitzgerald, but tells him to let go of Havens and return to the C.I.A. Miller is later drugged by a nurse, who turns out to be Havens. After Havens breaks Miller out of the hospital, he wakes up in the rebuilt GTO that belonged to her father. After Miller asks what day it is, Havens kisses him and says it's someday. This is a reference from the start of the movie that they both have things they want to do someday, and Havens begins to drive towards Cape Horn. As the credits begin to roll, Miller's parents unwittingly receive tickets to Cape Horn in the mail and accept to go.

Question: What is the perpetual energy battery called?
Answer: Zephyr