On the Reactivity of Li8-yMnyP4 toward Lithium

Frédéric Gillot (1) , Laure Monconduit (2) , Mathieu Morcrette (1) , Marie-Liesse Doublet (2) , Loic Dupont (1) , Jean‐marie Tarascon (1)

1 LRCS - Laboratoire réactivité et chimie des solides - UMR CNRS 7314
2 ICGM ICMMM - Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier

The Li5.5Mn2.5P4 and Li7MnP4 phases having a tetragonal structure (P4/nmm, a ) b ) 4.176(1) Å andc ) 5.978(1) Å) and a cubic structure (Fm3hm a ) 5.968(3) Å) were synthesized by a two-step process consisting in ball milling Li, Mn, and P powders followed by annealing at 800 °C under argon in a sealed stainless steel tube. The resulting materials were tested on Li cells between 0.01 and 2 V. Bothof them can reversibly react with Li, leading to reversible capacities as high as 1000 mAh/g, but only the Li5.5Mn2.5P4 electrode can nicely maintain its initial capacity upon cycling. The origin of such a difference was found in the partial decomposition of Li7MnP4 in Li3P and Mn nanoparticles at low potential, as deduced by in situ X-ray diffraction measurements. In contrast, no decomposition was shown to occur for the Li5.5Mn2.5P4 electrode that shows the best capacity retention among of ternary LixMyP4 (M ) Ti, V) so far studied

Domaines: Matériaux

Frédéric Gillot, Laure Monconduit, Mathieu Morcrette, Marie-Liesse Doublet, Loic Dupont, et al.. On the Reactivity of Li8-yMnyP4 toward Lithium. Chemistry of Materials, 2005, 17, pp.3627-3635. ⟨10.1021/cm050362b⟩. ⟨hal-00383215⟩