title: Calcium-based multi-element chemistry for grid-scale electrochemical energy storage.
abstract: Calcium is an attractive material for the negative electrode in a rechargeable battery due to its low electronegativity (high cell voltage), double valence, earth abundance and low cost; however, the use of calcium has historically eluded researchers due to its high melting temperature, high reactivity and unfavorably high solubility in molten salts. Here we demonstrate a long-cycle-life calcium-metal-based rechargeable battery for grid-scale energy storage. By deploying a multi-cation binary electrolyte in concert with an alloyed negative electrode, calcium solubility in the electrolyte is suppressed and operating temperature is reduced. These chemical mitigation strategies also engage another element in energy storage reactions resulting in a multi-element battery. These initial results demonstrate how the synergistic effects of deploying multiple chemical mitigation strategies coupled with the relaxation of the requirement of a single itinerant ion can unlock calcium-based chemistries and produce a battery with enhanced performance.
authors.affiliation: Department of Materials Science and Engineering, Massachusetts Institute of Technology 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, USA.
authors.forename: Takanari
authors.initials: T
authors.lastname: Ouchi
authors.affiliation: Department of Materials Science and Engineering, The Pennsylvania State University, 320 Forest Resources Laboratory, University Park, Pennsylvania 16802-4705, USA.
authors.forename: Hojong
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of Materials Science and Engineering, Massachusetts Institute of Technology 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, USA.
authors.forename: Brian L
authors.initials: BL
authors.lastname: Spatocco
authors.affiliation: Department of Materials Science and Engineering, Massachusetts Institute of Technology 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, USA.
authors.forename: Donald R
authors.initials: DR
authors.lastname: Sadoway