Micro-/Nanostructured Co₃O₄ Anode with Enhanced Rate Capability for Lithium-Ion Batteries

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 m²·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)