Novel layered double hydroxide precursor derived high-Co^sub 9^S^sub 8^-content composite as anode for lithium-ion batteries

Layered double hydroxides (LDHs), also known as brucite (Mg(OH)2)-like anionic clay compounds, are very convenient precursors with a unique flexibility of tuning component type and molar ratio toward composite nanomaterials in energy storage, such as lithium-ion batteries (LIBs). Conventional binary LDH precursors are typically converted to active/non-active transition-metal oxide composites as anode nanomaterials for LIBs, but either with the aid of additionally introducing highly conductive carbonaceous matrix, or possessing relatively high-content non-active components that greatly lower the reversible specific capacity. Herein, we demonstrate a rational design of a novel single-source precursor of dodecyl sulfonate-intercalated Co2+Co3+Al3+-layered double hydroxide (Co2+Co3+Al3+-LDH) and its conversion to high-Co9S8-content composite (Co9S8/S-doped carbon/Al2O3) as high-efficiency anode nanomaterials for LIBs. In-situ X-ray diffraction (XRD) reveals the controllable topotactic transformation via tuning calcination temperature and time. Electrochemical test shows that the composite electrode delivers a reversible capacity of 970 mA h g−1 after 200 cycles at 100 mA g−1, and in particular, a long-term cycling stability of 780 mA h g−1 after 500 cycles at 1 A g−1, manifesting highly enhanced electrochemical performances compared with the counterpart derived from a conventional binary LDH precursor. Monitoring the discharged/charged states by in-situ XRD and ex-situ Raman spectra provides a direct support to the enhancement. Our results show that the LDH precursor-based approach provides an alternative to prepare diverse transition metal sulfides for energy storage.