Co 0.8 Zn 0.2 MoO 4 /C Nanosheet Composite: Rational Construction via a One-Stone-Three-Birds Strategy and Superior Lithium Storage Performances for Lithium-Ion Batteries.

CoMoO ₄ has gained great attention as an anode material for lithium-ion batteries owing to its high theoretical capacity of 980 mAh g ^-1 and relatively high electrochemical activity. Unfortunately, CoMoO ₄ anode also has some drawbacks such as low electronic/ionic conductivity, inferior cyclic stability, and relative severe volumetric expansion during the lithiation/delithiation process, greatly inhibiting its further development and application. Herein, we report Co _0.8 Zn _0.2 MoO ₄ /C nanosheet composite constructed via a novel and facile one-stone-three-birds strategy. The preparation of the Co _0.8 Zn _0.2 MoO ₄ /C nanosheet is based on the following two-step process: the formation of Co/Zn nanosheet precursors derived from Co/Zn-ZIF rhombic dodecahedra via solvothermal pretreatment, followed by a calcination treatment with molybdic acid (H ₂ MoO ₄ ) in air. The as-prepared Co _0.8 Zn _0.2 MoO ₄ /C is monoclinic crystal structured composite with the in situ formed active carbon, which is well-defined nanosheet with a rough surface and mean thickness of 60-70 nm for a single sheet. This Co _0.8 Zn _0.2 MoO ₄ /C nanosheet composite possesses a larger surface area of 37.60 m ² g ^-1 , showing a mesoporous structure. When used as anode materials, the as-obtained Co _0.8 Zn _0.2 MoO ₄ /C composite can deliver as high as a discharge capacity of 1337 mAh g ^-1 after 300 cycles at 0.2C and still retain the capacity of 827 mAh g ^-1 even after 600 cycles at 1C, exhibiting outstanding lithium storage performances. The higher capacity and superior cyclic stability of the Co _0.8 Zn _0.2 MoO ₄ /C composite should be ascribed to the synergistic effect of the substitution of Zn ²⁺ , in situ composited active carbon and the as-constructed unique microstructure for the Co _0.8 Zn _0.2 MoO ₄ /C composite. Our present work provides a facile one-stone-three-birds strategy to effectively construct the architectures and significantly enhance electrochemical performances for other transition metal electrode materials.