Role of Electrocatalysts in the Li-Air System

Normally, the kinetics of ORR and OER occurring at the cathode of fuel cells, including direct methanol fuel cells (DMFCs) is very slow. In order to speed up the ORR kinetics to reach a practical usable level in a fuel cell, ORR catalyst is needed at the air cathode. Platinum (Pt)-based materials are the most practical catalysts used in PEM technology. These Pt-based catalysts are too expensive to make fuel cells commercially viable, and hence extensive research over the past several decades has been focused on development of alternative catalysts. These alternative electrocatalysts include noble metals and allo37S, carbon materials, quinone and its derivatives, transition metal macrocyclic compounds, transition metal chalcogenides, transition metal carbides and transition metal oxides. In this chapter, we focus on both noble and nonnoble electrocatalysts being used in air cathodes and the kinetics and mechanisms O2 reduction/oxidation reaction (both ORR and OER), catal37zed by them. 

Specific capacities of air cathodes vs. LiCo02 Li202 Li2 0 LiCo02 

Specific capacity with respect to carbon (mAh/g carbon) 4600 6000 Not applicable 

Specific energy density with respect to C+Li2 0x or LiCo02 (mWh/g cathode) 2450 3700 620 

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