Structure and Electrochemical Properties of La1-xBaxCoO3 Powders as Negative Electrode Materials for Ni/MH Batteries
The perovskite-type oxides have a newly application for alkaline batteries due to the excellent cyclic performance. In this work, La1-xBaxCoO3(x= 0.2, 0.4, 0.6) powders were prepared by a sol-gel method as negative electrode materials for Ni/MH batteries, and their phase structure and electrochemical properties were investigated in details. The effect of Ba substitution on electrochemical kinetic properties, including the exchange current densityI0and the hydrogen diffusion coefficientD, of La1-xBaxCoO3electrodes were also evaluated. X-ray diffraction analysis shows that La1-xBaxCoO3(x= 0.2, 0.4, 0.6) perovskite-type oxides consist of two phases, La0.5Ba0.5CoO3and BaCoO2.70. The discharge capacities of La1-xBaxCoO3negative electrodes tested at 40 mAg-1are 65.6, 76.6 and 88.3 mAhg-1whenx= 0.2, 0.4 and 0.6, respectively. Among the electrodes, La0.8Ba0.2CoO3electrode has the highest discharge capacity retention ratio of about 87% after 50 cycles at room temperature.