Ball-in-ball NiS@CoS heterojunction driven by Kirkendall effect for high-performance Mg/Li hybrid batteries.

Mg/Li hybrid batteries (MLHBs), which support the rapid insertion and removal of Mg/Li bimetallic ions, are promising energy storage systems. Inspired by the Kirkendall effect, ball-in-ball bimetallic sulfides with heterostructures were prepared as cathode materials for the MLHBs. First, a nickel-cobalt precursor (NiCo-X precursor) with three-dimensional (3D) nanosheets on its surface was prepared using a solvothermal method based on the association reaction between alkoxide molecules.