Molecular wiring of LiMnPO4 (olivine) by ruthenium(II)-bipyridine complexes

LiMnPO4 (olivine) was surface-modified by two different complexes: Ru-bis(4,4'-diethoxycarbonyl-2,2'-bipyridine)(4,4'-dicarboxylate-2,2'-bipyridine) and Ru-bis(4-carboxylic acid-4'-carboxylate-2,2'-bipyridine)(4,4'-dinonyl-2,2'bipyridine). These complexes have redox potentials of 4.45 and 4.25 V vs. Li/Li+, respectively, and are both active for molecular wiring of LiMnPO4. The surface-confined Ru(II)/Ru(III) redox reaction propagates across the monolayer via hole-hopping, allowing a subsequent chemical delithiation of the underneath olivine towards MnPO4. The activity of LiMnPO4 is about half of that of LiFePO4 (olivine) at similar experimental conditions. (C) 2009 Elsevier B.V. All rights reserved.