When an electric vehicle is parked outside, its temperature can swing wildly from day to night and season to season, which can lead to deterioration of the battery. To dampen these fluctuations and extend the battery's lifespan, researchers have designed an all-season thermal cloak that can cool an electric vehicle by 8°C on a hot day and warm it by 6.8°C at night. The cloak, made predominantly of silica and aluminum, can do so passively without outside energy input and operates without any modification between hot or cold weather. This prototype is described July 11 in the newly launched Device, an application-oriented sister journal to Matter, Joule, and Cell.