title: The influence of large cations on the electrochemical properties of tunnel-structured metal oxides.
abstract: Metal oxides with a tunnelled structure are attractive as charge storage materials for rechargeable batteries and supercapacitors, since the tunnels enable fast reversible insertion/extraction of charge carriers (for example, lithium ions). Common synthesis methods can introduce large cations such as potassium, barium and ammonium ions into the tunnels, but how these cations affect charge storage performance is not fully understood. Here, we report the role of tunnel cations in governing the electrochemical properties of electrode materials by focusing on potassium ions in α-MnO2. We show that the presence of cations inside 2 × 2 tunnels of manganese dioxide increases the electronic conductivity, and improves lithium ion diffusivity. In addition, transmission electron microscopy analysis indicates that the tunnels remain intact whether cations are present in the tunnels or not. Our systematic study shows that cation addition to α-MnO2has a strong beneficial effect on the electrochemical performance of this material.
authors.affiliation: Department of Materials Science and Engineering, Michigan Technological University, 1400 Townsend Drive, Houghton, Michigan 49931, USA.|Chemical Science and Engineering Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, Illinois 60439, USA.
authors.forename: Yifei
authors.initials: Y
authors.lastname: Yuan
authors.affiliation: Chemical Science and Engineering Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, Illinois 60439, USA.
authors.forename: Chun
authors.initials: C
authors.lastname: Zhan
authors.affiliation: Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, Illinois 60607, USA.
authors.forename: Kun
authors.initials: K
authors.lastname: He
authors.affiliation: Department of Chemistry, University of Bath, Bath BA2 7AY, UK.
authors.forename: Hungru
authors.initials: H
authors.lastname: Chen
authors.affiliation: Department of Mechanical Engineering, Michigan Technological University, 1400 Townsend Drive, Houghton, Michigan 49931, USA.
authors.forename: Wentao
authors.initials: W
authors.lastname: Yao
authors.affiliation: Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, Illinois 60607, USA.
authors.forename: Soroosh
authors.initials: S
authors.lastname: Sharifi-Asl
authors.affiliation: Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, Illinois 60607, USA.
authors.forename: Boao
authors.initials: B
authors.lastname: Song
authors.affiliation: Chemical Science and Engineering Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, Illinois 60439, USA.
authors.forename: Zhenzhen
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, Illinois 60607, USA.|Materials Genome Institute and Shanghai Materials Genome Institute, Shanghai University, 99 Shangda Road, Shanghai 200444, China.
authors.forename: Anmin
authors.initials: A
authors.lastname: Nie
authors.affiliation: Chemical Science and Engineering Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, Illinois 60439, USA.
authors.forename: Xiangyi
authors.initials: X
authors.lastname: Luo
authors.affiliation: Chemical Science and Engineering Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, Illinois 60439, USA.
authors.forename: Hao
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Chemistry, University of Bath, Bath BA2 7AY, UK.
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Wood
authors.affiliation: Chemical Science and Engineering Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, Illinois 60439, USA.
authors.forename: Khalil
authors.initials: K
authors.lastname: Amine
authors.affiliation: Department of Chemistry, University of Bath, Bath BA2 7AY, UK.
authors.forename: M Saiful
authors.initials: MS
authors.lastname: Islam
authors.affiliation: Chemical Science and Engineering Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, Illinois 60439, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Lu
authors.affiliation: Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, Illinois 60607, USA.|Department of Mechanical Engineering, Michigan Technological University, 1400 Townsend Drive, Houghton, Michigan 49931, USA.
authors.forename: Reza
authors.initials: R
authors.lastname: Shahbazian-Yassar