(35d) 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_xcatalyzed
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