Imagine not having to charge your phone or laptop for weeks. That is the dream of researchers looking into alternative batteries that go beyond the current lithium-ion versions popular today. Now, in a new study appearing in the journal Science, chemists at several institutions, including Caltech and the Jet Propulsion Laboratory, which is managed by Caltech for NASA, as well as the Honda Research Institute and Lawrence Berkeley National Laboratory, have hit on a new way of making rechargeable batteries based on fluoride, the negatively charged form, or anion, of the element fluorine.