title: Ultrafast Solvent-Assisted Sodium Ion Intercalation into Highly Crystalline Few-Layered Graphene.
abstract: A maximum sodium capacity of ∼35 mAh/g has hampered the use of crystalline carbon nanostructures for sodium ion battery anodes. We demonstrate that a diglyme solvent shell encapsulating a sodium ion acts as a "nonstick" coating to facilitate rapid ion insertion into crystalline few-layer graphene and bypass slow desolvation kinetics. This yields storage capacities above 150 mAh/g, cycling performance with negligible capacity fade over 8000 cycles, and ∼100 mAh/g capacities maintained at currents of 30 A/g (∼12 s charge). Raman spectroscopy elucidates the ordered, but nondestructive cointercalation mechanism that differs from desolvated ion intercalation processes. In situ Raman measurements identify the Na(+) staging sequence and isolates Fermi energies for the first and second stage ternary intercalation compounds at ∼0.8 eV and ∼1.2 eV.
authors.affiliation: Department of Mechanical Engineering and ‡Interdisciplinary Materials Science Program, Vanderbilt University , Nashville, Tennessee 37235, United States.
authors.forename: Adam P
authors.initials: AP
authors.lastname: Cohn
authors.affiliation: Department of Mechanical Engineering and ‡Interdisciplinary Materials Science Program, Vanderbilt University , Nashville, Tennessee 37235, United States.
authors.forename: Keith
authors.initials: K
authors.lastname: Share
authors.affiliation: Department of Mechanical Engineering and ‡Interdisciplinary Materials Science Program, Vanderbilt University , Nashville, Tennessee 37235, United States.
authors.forename: Rachel
authors.initials: R
authors.lastname: Carter
authors.affiliation: Department of Mechanical Engineering and ‡Interdisciplinary Materials Science Program, Vanderbilt University , Nashville, Tennessee 37235, United States.
authors.forename: Landon
authors.initials: L
authors.lastname: Oakes
authors.affiliation: Department of Mechanical Engineering and ‡Interdisciplinary Materials Science Program, Vanderbilt University , Nashville, Tennessee 37235, United States.
authors.forename: Cary L
authors.initials: CL
authors.lastname: Pint
keywords: Graphene; Na+; anode; graphene intercalation compounds; in situ Raman spectroscopy; sodium ion batteries; solvent cointercalation