title: On the Oxidation State of Manganese Ions in Li-Ion Battery Electrolyte Solutions.
abstract: We demonstrate herein that Mn3+and not Mn2+, as commonly accepted, is the dominant dissolved manganese cation in LiPF6-based electrolyte solutions of Li-ion batteries with lithium manganate spinel positive and graphite negative electrodes chemistry. The Mn3+fractions in solution, derived from a combined analysis of electron paramagnetic resonance and inductively coupled plasma spectroscopy data, are ∼80% for either fully discharged (3.0 V hold) or fully charged (4.2 V hold) cells, and ∼60% for galvanostatically cycled cells. These findings agree with the average oxidation state of dissolved Mn ions determined from X-ray absorption near-edge spectroscopy data, as verified through a speciation diagram analysis. We also show that the fractions of Mn3+in the aprotic nonaqueous electrolyte solution are constant over the duration of our experiments and that disproportionation of Mn3+occurs at a very slow rate.
authors.affiliation: Department of Chemistry, Bar-Ilan University , Ramat-Gan 5290002, Israel.
authors.forename: Anjan
authors.identifier: 0000-0002-5658-4610
authors.initials: A
authors.lastname: Banerjee
authors.affiliation: Department of Chemistry, Bar-Ilan University , Ramat-Gan 5290002, Israel.
authors.forename: Yuliya
authors.initials: Y
authors.lastname: Shilina
authors.affiliation: Department of Chemistry, Bar-Ilan University , Ramat-Gan 5290002, Israel.
authors.forename: Baruch
authors.initials: B
authors.lastname: Ziv
authors.affiliation: Fuel Cell R&D, General Motors Global Propulsion Systems , Warren, Michigan 48092-2031, United States.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Ziegelbauer
authors.affiliation: Department of Chemistry, Bar-Ilan University , Ramat-Gan 5290002, Israel.
authors.forename: Shalom
authors.initials: S
authors.lastname: Luski
authors.affiliation: Department of Chemistry, Bar-Ilan University , Ramat-Gan 5290002, Israel.
authors.forename: Doron
authors.identifier: 0000-0002-1151-546X
authors.initials: D
authors.lastname: Aurbach
authors.affiliation: Chemical and Materials Systems Lab, General Motors Global R&D , Warren, Michigan 48092-2031, United States.
authors.forename: Ion C
authors.initials: IC
authors.lastname: Halalay