Low-valence bicomponent (FeO)x(MnO)1−x nanocrystals embedded in amorphous carbon as high-performance anode materials for lithium storage

Abstract

Bicomponent transition metal monoxides (BTMMOs) are considered as promising electrode materials due to the fact that they are rich in lower valence states of transition metals. However, BTMMOs are rarely utilized as electrode materials for lithium ion batteries. Herein, we report the synthesis of nearly uniform monodisperse bicomponent iron manganese oxide, (FeO)_x(MnO)_1−x nanocrystals encapsulated in amorphous carbon, via liquid–solid solution and Baeyer's reagent routes and used them as a high-performance anode material for lithium ion batteries. The (FeO)_x(MnO)_1−x nanocrystals can be obtained by using inexpensive simple iron salt, oleic acid and manganese metal salts as reactants. The interaction of the Mn salt via the Baeyer's reagent route induces metal cations in the form of low oxidation states. In the presence of low valence states in the BTMMO electrode, the formation of irreversible Li₂O and high initial coulombic efficiency (ICE) can be suppressed for enhancing the electrochemical properties of the electrodes. Density functional theory (DFT) calculations are used to study the electron density redistribution in the BTMMO samples. The optimized bicomponent (FeO)_0.198(MnO)_0.802 electrode displayed excellent lithium storage performance which is superior to those of (FeO)_0.331(MnO)_0.669 and MTMO electrodes. This work will not only create an opportunity for the synthesis of monodisperse bicomponent transition metal oxides but also their exploration as electrode materials for energy storage devices.