Unravelling redox processes of Li7MnN4 upon electrochemical Li extraction-insertion using &IToperando &ITXAS

作者：Muller Bouvet D; Emery N^*; Tassali N; Panabiere E; Bach S; Crosnier O; Brousse T; Cenac Morthe C; Michalowicz A^*; Pereira Ramos J P

来源：Physical Chemistry Chemical Physics, 2017, 19(40): 27204-27211.

DOI：10.1039/c7cp05207c

A large data set of XAS (X-ray Absorption Spectroscopy) Manganese K-edge spectra has been collected operando and studied upon the electrochemical oxidation of the promising Li-ion battery anode material Li7MnN4. Using chemometric tools such as PCA (Principal Component Analysis) and MCR-ALS (Multivariate Curve resolution - Alternating Least Squares), three independent environment spectra were insulated. Based on the faradaic yield and well-chosen comparison of absorption spectrum energies within the frame of the coordination charge model, these environments were ascribed to unusual oxidation states allowed by nitride chemistry at a low potential (similar to 1.2 V vs. Li+/Li), i.e. Mn5+ (3d(2)), Mn6+ (3d(1)) and Mn-7 (3d). Also, their relative amounts are discussed with regard to the long-range structural variation which can be simply described by two successive biphasic domains followed by a solid-solution behaviour. Gathering this long-range and local structure information provides a complete picture of the redox mechanisms occurring in Li7MnN4.

• 出版日期2017-10-28