Structure and Electrochemical Properties of La_1-_xBa_xCoO₃ Powders as Negative Electrode Materials for Ni/MH Batteries

E-ISSN： 1662-9752|2015|814|113-117

ISSN： 0255-5476

Source： Materials Science Forum, Vol.2015, Iss.814, 2015-04, pp. : 113-117

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Abstract

The perovskite-type oxides have a newly application for alkaline batteries due to the excellent cyclic performance. In this work, La_1-_xBa_xCoO₃ (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 density I₀ and the hydrogen diffusion coefficient D, of La_1-_xBa_xCoO₃ electrodes were also evaluated. X-ray diffraction analysis shows that La_1-_xBa_xCoO₃ (x = 0.2, 0.4, 0.6) perovskite-type oxides consist of two phases, La_0.5Ba_0.5CoO₃ and BaCoO_2.70. The discharge capacities of La_1-_xBa_xCoO₃ negative electrodes tested at 40 mAg^-1 are 65.6, 76.6 and 88.3 mAhg^-1 when x = 0.2, 0.4 and 0.6, respectively. Among the electrodes, La_0.8Ba_0.2CoO₃ electrode has the highest discharge capacity retention ratio of about 87% after 50 cycles at room temperature.