title: Na2Ti3O7Nanoplatelets and Nanosheets Derived from a Modified Exfoliation Process for Use as a High-Capacity Sodium-Ion Negative Electrode.
abstract: The increasing interest in Na-ion batteries (NIBs) can be traced to sodium abundance, its low cost compared to lithium, and its intercalation chemistry being similar to that of lithium. We report that the electrochemical properties of a promising negative electrode material, Na2Ti3O7, are improved by exfoliating its layered structure and forming 2D nanoscale morphologies, nanoplatelets, and nanosheets. Exfoliation of Na2Ti3O7was carried out by controlling the amount of proton exchange for Na+and then proceeding with the intercalation of larger cations such as methylammonium and propylammonium. An optimized mixture of nanoplatelets and nanosheets exhibited the best electrochemical performance in terms of high capacities in the range of 100-150 mA h g-1at high rates with stable cycling over several hundred cycles. These properties far exceed those of the corresponding bulk material, which is characterized by slow charge-storage kinetics and poor long-term stability. The results reported in this study demonstrate that charge-storage processes directed at 2D morphologies of surfaces and few layers of sheets are an exciting direction for improving the energy and power density of electrode materials for NIBs.
authors.affiliation: Department of Materials Science and Engineering, University of California, Los Angeles , Los Angeles, California 90095, United States.
authors.forename: Jesse S
authors.identifier: http://orcid.org/0000-0001-6965-4174
authors.initials: JS
authors.lastname: Ko
authors.affiliation: California NanoSystems Institute, University of California, Santa Barbara , Santa Barbara, California 93106, United States.|Materials Research Laboratory, University of California, Santa Barbara , Santa Barbara, California 93106, United States.
authors.forename: Vicky V T
authors.identifier: http://orcid.org/0000-0003-4204-3271
authors.initials: VV
authors.lastname: Doan-Nguyen
authors.affiliation: Department of Materials Science and Engineering, University of California, Los Angeles , Los Angeles, California 90095, United States.
authors.forename: Hyung-Seok
authors.initials: HS
authors.lastname: Kim
authors.affiliation: Department of Materials Science and Engineering, University of California, Los Angeles , Los Angeles, California 90095, United States.
authors.forename: Guillaume A
authors.initials: GA
authors.lastname: Muller
authors.affiliation: Department of Materials Science and Engineering, University of California, Los Angeles , Los Angeles, California 90095, United States.
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Serino
authors.affiliation: Department of Materials Science and Engineering, University of California, Los Angeles , Los Angeles, California 90095, United States.|Department of Chemistry and Biochemistry, University of California, Los Angeles , Los Angeles, California 90095, United States.|California NanoSystems Institute, University of California, Los Angeles , Los Angeles, California 90095, United States.
authors.forename: Paul S
authors.identifier: http://orcid.org/0000-0001-5527-6248
authors.initials: PS
authors.lastname: Weiss
authors.affiliation: Department of Materials Science and Engineering, University of California, Los Angeles , Los Angeles, California 90095, United States.|California NanoSystems Institute, University of California, Los Angeles , Los Angeles, California 90095, United States.
authors.forename: Bruce S
authors.initials: BS
authors.lastname: Dunn
keywords: 2D materials; Na-ion battery; anode; electrochemistry; high rate; nanomaterials