Preparation of alpha-Fe2O3 electrode materials via solution process and their electrochemical properties in all-solid-state lithium batteries

alpha-Fe2O3 particles of various sizes were prepared by a solution process and were applied to the electrodes for all-solid-state lithium rechargeable batteries. The prepared alpha-Fe2O3 was monodispersed particles with sizes controlled from about 250 nm to 3.7 mu m. Their electrochemical properties were examined for the all-solid-state cells with highly conductive Li2S-P2S5 solid electrolytes and the influences of the particle size of alpha-Fe2O3 on the electrochemical performance of the cells were investigated. The first discharge capacities increased with decreasing the particle size of alpha-Fe2O3 and the cell using the smallest alpha-Fe2O3 particles of 250 nm showed the highest capacity of 1050 mAh g(-1). The charge-discharge reaction mechanism in the all-solid-state cells was investigated by means of X-ray diffraction and was revealed to be similar to that in conventional cells with a liquid electrolyte. The lithium intercalation to alpha-Fe2O3 occurred in the initial stage of the first discharge only in the cases using alpha-Fe2O3 particles with small crystallite size, large specific surface area and large pore volume. By controlling the cutoff voltage, the all-solid-state cell retained the constant capacity of about 130 mAh g(-1) for 15 cycles at the current density of 0.064 mA cm(-2). The rate capability at 25 degrees C and temperature dependence of the first discharge capacity in the all-solid-state cells were also investigated. The cell at 60 degrees C showed the larger first-discharge capacity of 940 mAh g(-1) at the current density of 1.27 mA cm(-2). (C) 2007 The Electrochemical Society.