title: MnO Conversion in Li-Ion Batteries: In Situ Studies and the Role of Mesostructuring.
abstract: Complex manganese oxides have been extensively studied as intercalation Li-ion battery electrodes. The simple oxide MnO has been proposed as a conversion anode material with a theoretical capacity of 756 mAh g(-1) for full reduction to the metal. We report the reaction of MnO with Li using in situ X-ray diffraction and find no sign of crystalline products upon either discharge or charge. However, the absence of reflections, paired with electrochemical impedance spectroscopy, suggests disordered discharge products. We also examine composite electrodes with porous particles of MnO as the active component, with pores generated through the reductive heating of Mn3O4. We compare the behavior of these with more dense MnO powders, including studies of the electrode morphologies pre- and postcyling. We find differences in the first discharge relevant to the utility of such mesostructuring in conversion reaction materials. Specifically, we find this type of mesostructure, which gives advantage in intercalation and pseudocapacitive storage, does not yield the same benefits for conversion reaction systems.
authors.affiliation: Materials Department and Materials Research Laboratory University of California, Santa Barbara , Santa Barbara, California 93106, United States.|Mitsubishi Chemical Center for Advanced Materials University of California, Santa Barbara , Santa Barbara, California 93106, United States.
authors.forename: Megan M
authors.initials: MM
authors.lastname: Butala
authors.affiliation: Materials Department and Materials Research Laboratory University of California, Santa Barbara , Santa Barbara, California 93106, United States.|Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom.
authors.forename: Katherine R
authors.initials: KR
authors.lastname: Danks
authors.affiliation: Mitsubishi Chemical Center for Advanced Materials University of California, Santa Barbara , Santa Barbara, California 93106, United States.|Department of Chemistry and Biochemistry University of California, Santa Barbara , Santa Barbara, California 93106, United States.
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Lumley
authors.affiliation: Department of Chemistry, University of Southern California, Los Angeles , Los Angeles, California 90089, United States.
authors.forename: Shiliang
authors.initials: S
authors.lastname: Zhou
authors.affiliation: Department of Chemistry, University of Southern California, Los Angeles , Los Angeles, California 90089, United States.
authors.forename: Brent C
authors.initials: BC
authors.lastname: Melot
authors.affiliation: Materials Department and Materials Research Laboratory University of California, Santa Barbara , Santa Barbara, California 93106, United States.|Mitsubishi Chemical Center for Advanced Materials University of California, Santa Barbara , Santa Barbara, California 93106, United States.
authors.forename: Ram
authors.initials: R
authors.lastname: Seshadri
keywords: conversion electrode; in situ XRD; lithium-ion battery; manganese oxide; mesoporosity; transition metal oxide