Evaluation of Ni-Mo Oxide (Ni-MoOx) Electrocatalyst for Li-Air Battery

 Evaluation of Ni-Mo Oxide (Ni-MoO_x) Electrocatalyst for Li-air Battery

Jamie Gomez^[1], Egwu E. Kalu^[1], Ruben Nelson^[2],

Mark H. Weatherspoon^[2], Jim P. Zheng ^[2]

^[1] Department of Chemical and Biomedical Engineering

^[2] Department of Electrical & Computer Engineering

FAMU-FSU College of Engineering

Tallahassee, FL, 32310

   The direct electro-reduction of oxygen as the active cathode process in the Li-Air battery has been identified as a major advantage of the Li-Air battery system. Unfortunately, the challenges on the air cathode system include the identification of appropriate catalyst for oxygen reduction in the non-aqueous media. The present talk will focus on the synthesis of composite Ni-Mo oxide electrocatalyst on woven and non-woven carbon fiber. The approach differs from the current practice that utilizes carbon particles as the catalyst support and uses classical impregnation method for the synthesis of catalyst metal nanoparticles.

     In our approach, electroless Ni-Mo composite metal was deposited on woven/non-woven carbon fiber. The oxidation of the Nickel/molybdenum metal coated on woven/non-woven carbon support was performed electrolytically to form Nickel/molybdenum oxide. A three-electrode system was used at constant potential to activate and form active metal catalyst oxides. 

     Preliminary results show that the metal oxide catalysts formed on the woven/non-woven- carbon cathode can enhance the discharge capacity of the lithium air cell. The specific discharge capacity of the nickel/molybdenum oxide (Ni-MoO_x) catalyzed woven-carbon cathode was determined to be 1210 mAh g^-1 whereas cobalt oxide (CoO_x) catalyzed carbon cathode yielded a discharge capacity of 687 mAh g^-1 at charging voltages of 4.2 V. These results indicate not only the superior performance of the Ni-MoO_x catalyzed woven-carbon cathode but also the significant role the oxide electrocatalyst plays in the electrochemistry of the air electrode. Figure 2 compares the preliminary discharge times of different electrocatalysts. Results on the kinetics of oxygen reduction in non-aqueous  media using Ni-MoOx electrocatalyst will be presented including the texture and micro-texture characterization of the composite metal oxide catalyzed carbons. Correlation s of electrocatalyst synthesis conditions with their electrochemical performance will be presented.

Figure 1: Discharge capapcity of Li-air battery using Ni-MoO_x catalyzed woven- carbon cathode at 0.314mA/ cm²

Figure 1:  Comparison of discharge profiles of Li-air battery using different catalyzed woven- carbon cathodes at 0.314 mA/cm²