Facile Electrochemical Activity of Monoclinic Li 2 MnSiO 4 as Potential Cathode for Li-Ion Batteries

• Published in: ACS applied materials & interfaces 2019-08, Vol.11 (32), p.28868-28877
• Main Authors: Shree Kesavan, K, Michael, M S, Prabaharan, S R S
• Format: Article
• Language: English
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.9b08213

Synthesis of pure single-phase Li MnSiO is challenging because of its rich polymorphism. Here, we demonstrate our success in preparing crystalline pure, battery-grade monoclinic phase Li MnSiO (LMS) employing the temperature-programmed reaction technique. Systematic analysis of the electrochemical behavior of Li MnSiO reveals its excellent battery activity in the monoclinic phase, with an initial discharge capacity of ∼250 mAh g associated with the reversible intercalation of more than one Li . The extraction of Li ions from Li MnSiO corresponding to the oxidation of Mn to Mn then to Mn appears as single oxidation/reduction peaks at 4.3/3.9 V in the first charge/discharge sweep of cyclic voltammogram within the potential window of 3.0-4.4 V. However, an extension of cathodic sweep to 2.5 V results in the appearance of an additional redox peak at 2.7/3.1 V vs Li /Li due to the reversible phase transition of monoclinic phase into battery-active orthorhombic phase induced by Jahn-Teller-active Mn as evident from ex situ X-ray diffractograms. Indeed, the reversible intercalation of Li into the newly formed phase accounts for the high specific capacity of LMS within the potential window of 2.5-4.4 V. The capacity loss in the repeated cycles of monoclinic Li MnSiO is explained by the formation of Mn O owing to the dissolution of Mn .