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Through a facile hydrothermal method with a special surfactant triethanolamine (TEA) followed by thermal treatment, monodispersed micro-/nanostructured Co3O4 powders with unique morphology (cube) have been synthesized successfully as anode material for Li-ion batteries (LIBs). The regular Co3O4 microcubes (∼2.37 μm in the average side length) consist of many irregular nanoparticles (20-200 nm in diameter, 30-40 nm in thickness) bonded to each other, which greatly inherit the morphology and size of the precursor CoCO3. The specific surface area of Co3O4 powders is about 5.10 m(2)·g(-1) by the Brunauer-Emmett-Teller (BET) method, and the average pore size is about 3.08 nm by the Barrett-Joyner-Halenda (BJH) method. In addition, the precursor is verified as a single-crystal, while the mesoporous cubic Co3O4 is a polycrystalline characteristic assembled by numerous single-crystal nanoparticles. More remarkable, the high performance of the micro-/nanostructured cubic Co3O4 powders has been obtained by the electrochemical measurements including high initial discharge capacities (1298 mAhg(-1) at 0.1 C and 1041 mAhg(-1) at 1 C), impressive rate capability, and excellent capacity retention (99.3%, 97.5%, 99.2%, and 89.9% of the first charge capacities after 60 cycles at 0.1 C, 0.2 C, 0.5 C, and 1 C, respectively).

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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 μm in the long axis, 1.5-2.5 μm 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 (∼900.0 mAhg(-1) after 60 cycles at 0.1 Ag(-1)), and fair rate performance (∼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).

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We report the designed synthesis of unique Co 9 S 8 nanoparticles encapsulated in nitrogen-doped mesoporous carbon networks (Co 9 S 8 @NMCN nanocomposites). Uniform zeolitic imidazolate framework-67 are first synthesized and then transformed into Co 9 S 8 @NMCN nanocomposites by thermal annealing with sulfur powders in Ar atmosphere. The structural and compositional analysis are conducted by employing X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS), which show that each Co 9 S 8 nanoparticle is well encapuslated in nitrogen-doped carbon layers. When evaluated as anode material for LIBs, the as-prepared composite electrodes delivered superior capacity, excellent cycling stability and rate capability, which are attributed to the advantageous structural features. Graphic AbstractCo 9 S 8 nanoparticles encapsulated in nitrogen-doped mesoporous carbon networks have been successfully synthesized by annealing a cobalt containing metal organic framework with sulfur powders in Ar atmosphere. The resultant products exhibit excellent lithium storage properties.