Thursday, March 08, 2012

Facile Solvothermal Synthesis of Phase-Pure Cu4O3 Microspheres and Their Lithium Storage Properties

In order to tackle new challenges met in the development of modern industry and society, it is imperative to develop materials with high energy and power density, particular electrodes in Li-ion batteries. Transition-metal oxides (TMOs, where TM = Co, Fe, Ni, Cu, etc.) have been regarded as potential candidates for anode materials. This is because lithium can be stored reversibly in TMOs through a heterogeneous conversion reaction: Li + TMO Li2O + TM, which involves the formation and decomposition of Li2O via the reduction and oxidation of metal nanoparticles, different from the classical Li insertion/desertion or Li-alloying processes. Although CuO (tenorite or cupric oxide) and Cu2O (cuprite or cuprous oxide) have been extensively investigated as potential anode materials for Li-ion batteries, the electrochemical lithium storage properties of Cu4O3 have never been reported.

Phase-pure Cu4O3 microspheres were synthesized for the first time via a facile solvothermal method, using Cu(NO3)2·3H2O as the precursor. A formation mechanism was proposed based on the observation of a series of reaction intermediates. The samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, temperature-programmed reduction and oxidation, X-ray photoelectron spectroscopy, and nitrogen adsorption. It was found that the composition of the prepared products were highly dependent on the synthesis conditions, particularly the hydrate water content in the copper precursor of Cu(NO3)2. Pure Cu4O3 microspheres with a diameter of 2–10 μm could be obtained via the symproportionation reaction (2CuO + Cu2O Cu4O3), which was regarded not being feasible in aqueous media under mild synthesis conditions. The electrochemical properties of the Cu4O3 microspheres as anode materials for Li-ion batteries were also investigated. Compared to the simple physical mixture of CuO and Cu2O with an equivalent atomic ratio of 2:1, the as-prepared Cu4O3 exhibited unique lithium storage behaviors at a low voltage range and superior electrochemical performances as an anode material for Li-ion batteries. The successful preparation of pure Cu4O3 material could provide opportunities to further explore its physicochemical properties and potential applications.

Zhao, L. Chen, H. Wang, Y.( Facile Solvothermal Synthesis of Phase-Pure Cu4O3 Microspheres and Their Lithium Storage Properties. February 23 , 2012.

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