Co0.8Zn0.2MoO4/C Nanosheet Composite: Rational Construction via a One-Stone-Three-Birds Strategy and Superior Lithium Storage Performances for Lithium-Ion Batteries

CoMoO4 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, CoMoO4 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 Co0.8Zn0.2MoO4/C nanosheet composite constructed via a novel and facile one-stone-three-birds strategy. The preparation of the Co0.8Zn0.2MoO4/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 (H2MoO4) in air. The as-prepared Co0.8Zn0.2MoO4/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 Co0.8Zn0.2MoO4/C nanosheet composite possesses a larger surface area of 37.60 m2 g–1, showing a mesoporous structure. When used as anode materials, the as-obtained Co0.8Zn0.2MoO4/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 Co0.8Zn0.2MoO4/C composite should be ascribed to the synergistic effect of the substitution of Zn2+, in situ composited active carbon and the as-constructed unique microstructure for the Co0.8Zn0.2MoO4/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.