Green molten salt modification of cobalt oxide for lithium ion battery anode application.

The clean and low-cost preparation of advanced materials for green energy storage applications is a critical step towards sustainable development. Here, the rapid modification of CoO in molten salt is proposed as a low-cost approach for the scalable preparation of Co-based oxides with enhanced Li-storage performance. The phase evolution of CoO upon molten salt treatment is investigated by X-ray diffraction (XRD), electron microscopy, N 2 adsorption–desorption and Raman spectroscopy. The molten salt treatment of CoO under dry and humid Ar atmosphere leads to the formation of dual-phase structured CoO/Co 3 O 4 and Li 0.065 Co 0.935 O, respectively. High resolution transmission electron microscopy and fast Fourier transform analysis of samples after Li insertion and extraction process confirm the formation of nanostructured Co-Li 2 O. The Co phase formed from CoO/Co 3 O 4 and Li 0.065 Co 0.935 O is found to have hexagonal close packed (hcp) and face central cubic (fcc) structure, respectively. The Li-storage performances of these materials are correlated to their structural/microstructural characteristics. This article presents a simple, scalable and environmentally-friendly approach for modification of Co-oxide materials for lithium ion battery anode applications. • Potentially sustainable modification of CoO in high-temperature molten salts. • Molten sat formation of Li 0.065 Co 0.935 O in humid atmosphere and mechanisms. • Preparation of dual-phase structured CoO/Co 3 O 4 in dry atmosphere and mechanisms. • Correlation between structural/morphological features and Li-storage performance. • Formation of nanostructured hybrid Co-Li 2 O with cubic- or hexagonal-Co. [ABSTRACT FROM AUTHOR]