A New Type Orthorhombic LiFeO2 with advanced Battery Performance

Abstract

The o-LiFeO2 material was synthesized using LiOHH2O and r-FeOOH. The mixture of LiOH and r-FeOOH was thoroughly gound in an agate and calcined at various temperatures. The powder X-ray diffraction(XRD) using Cu ka radiation was performed to identify the crystalline phase of the materials. The electrochemical characterization were performed using CR2032 coin-type cells. The electrolyte used was a 1M LIPF6-EC/ DMC (1:2 by vol). The charge-discharge current density was 0.1mA/cm2 with a cut-off voltage of 2.0 to 4.5 V. Orthorhombic LiFeO2 was synthesized using LiOH and r-FeOOH starting materials. X-ray diffraction revealed that LiFeO2 showed a well-defined ortorhombic phase of a Pmnm space group although it also showed some impurities such as a-LiFeO2. The lattice constants of the resulting compound ard a=4.04A, b=2.97A, and c=6.07A. The LiFeO2 delivered 147mAh/g in the first cycle and still delivered 127mAh/g after 15 cycles at room temperature. The well defined orthorhombic LiFeO2 compound which obtained by solid state method exhibited superior to the electrochemical performance compared with that of ion-exchange method.