Mixed transition-metal oxides@carbon core-shell nanostructures derived from heterometallic clusters for enhanced lithium storage

Multicomponent binary metal oxide-involved hybrid structures with unique physicochemical properties have received extensive attention due to their fascinating electrochemical performance. Herein, a flexible strategy, which involves the preparation of dual-functional heterometallic Fe₂M clusters and their subsequent sintering treatment, is developed to engineer novel 3D hierarchical porous structures assembled with MFe₂O₄ (M = Co, Mn, Ni and Zn) nanoparticles confined within carbon outer shell (denoted as MFe₂O₄@C HPSs). In this intriguing construction, it can be observed that MFe₂O₄@C HPSs comprised of carbon coated secondary MFe₂O₄ nanoparticles with an interconnected carbon network. The as-prepared MFe₂O₄@C HPSs possess combined advantages of high capacity of MFe₂O₄ and high conductivity of carbon. As expected, the MFe₂O₄@C HPSs offer a high reversible capacity, high cycling stability and superior rate performance. The interconnected conductive carbon shells facilitates fast ion and electron transport and accommodates the mechanical strain. In addition, nanosized MFe₂O₄ particles, which shorten the ion-transport path and provide extra electroactive sites, also improve the reaction kinetics. Moreover, these MFe₂O₄@C HPSs exhibit good structural integrity during repeated charging and discharging. The research perspective and strategy reported here are highly versatile and shed new light on the synthesis of other advanced electrode for various applications.