An exemplary battery assembly includes a shield having a floor and walls extending transversely away from the floor. The shield provides a cavity configured to receive a battery pack of an electrified vehicle. The cavity is larger than the traction battery pack so that there is a gap between at least some of the walls and the traction battery pack within the cavity. An exemplary shielding method includes securing a shield to a vehicle frame to enclose a traction battery pack held within a cavity of the shield.