In this study, novel core-shell ellipsoidal MnCo2O4 powders with desired micro/nano-structure and a unique concentration gradient have been synthesized as anode material for Li-ion batteries. The special porous ellipsoid (2.5-4.5 mu m in the long axis, 1.5-2.5 mu m in the short axis, 200-300 nm in the thickness of shell) is built up by irregular nanoparticles attached to each other, and corresponding to the ellipsoid with concentration gradient, the Co/Mn atomic ratios of core and shell are about 1.76:1 and 2.34:1, respectively. The good performance, including high initial discharge capacities (1433.3 mAhg-1 at 0.1 Ag-1 and 1248.4 mAhg-1 at 0.4 Ag-1), advanced capacity retention (similar to 900.0 mAhg-1 after 60 cycles at 0.1 Ag-1), and fair rate performance (similar to 620.0 mAhg-1 after 50 cycles at 0.4 Ag-1) has been measured by the battery test. Remarkably, the ellipsoidal shape and core-shell microstructure with concentration gradient are still maintained after 70 cycles of charge/discharge at 0.1 Ag-1.
- Concentration gradient