Preparations And Electrochemical Properties Of Layered Double Hydroxide Precursor-Based Transition Metal Oxides

Energy issues are the global focus and hot issues of common concern. Lithium-ion batteries (LIBs) have been applied successfully in the field of mobile electronic devices, electric vehicles and power tools, and also challenged by increasing demand on high-capacity, high-rate and long cycle capacibilities. Transition metal compounds (NiX, X=O, P, S) as one type of potential anode materials for LIBs suffer the common problem of poor cycling stability due to pronounced structural changes and poor electronic conductivity of active anode materials. Layered double hydroxides (LDHs), being one important type of multifunctional layered materials, have been of increasing interest in recent years in many basic and applied research fields. Utilization of thermal decomposition of LDHs can be an effective way to prepare uniformly distributed bi-metal oxide composite. We herein have demonstrated the facile preparations of carbon/nickel-containing transition metal compounds (NiO、 Ni3P and Ni3S2) derived from LDHs precursors. The obtained nanocomposites are able to exhibit highly enhanced electrochemical performances when used as anode materials for LIBs. The main results and innovations are as follows.(1) C-Ni@NiO/Al2O3nanocomposite is obtained by decomposition of NiAl-LDH/C precursor prepared by a scalable method of separate nucleation and aging process. The nanocomposite has the characteristics of Ni core/NiO shell structure, and uniform particle distribution, and thus exhibit highly enhanced electrochemical properties in comparison with the commercial nickel oxide.(2) Carbon-encapsulated Ni3P (C@Ni3P/Ni/C) nanocomposite is obtained fancily by calcining the precursor of intercalated sodium dodecyl phosphate/Ni(OH)2. The advantages of this method is to utilize dual roles of the guest molecule as clever phosphorus and carbonaceous sources, efficient and environmentally friendly preparation process, as well as avoiding the use of organic phosphorus. Electrochemical tests showed that the nanocomposite can deliver a specific capacity of635mA h g-1under a current density of100mA g-1upon a reversible cycling of up to200times. And the average Coulombic efficiency stabilizes above97%during the charge-discharge processes.Furthermore, this facile method can be extended to the sulfide nanocomposite (C@Ni3S2/Ni/Al2O3) prepared by a simple choice of the surfactant (SDS). The C@Ni3S2/Ni/Al2O3nanocomposite also showed significantly improved electrochemical properties, due to similarity in composition and structure to the C@Ni3P/Ni/C nanocomposite.