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Article Dans Une Revue Chemistry of Materials Année : 2005

Electrochemical Reactivity and Design of NiP2 Negative Electrodes for Secondary Li-Ion Batteries

Résumé

We report the electrochemical study of cubic and monoclinic NiP2 polymorphs toward Li, as a candidate for anodic applications for Li-ion batteries. We found that the monoclinic form is the most attractive one performance-wise. Monoclinic NiP2 can reversibly uptake 5 lithium per formula unit, leading to reversible capacities of 1000 mAh/g at an average potential of 0.9 V vs Li+/Li°. From complementary X-ray diffraction (XRD) and HRTEM (high-resolution transmission electron microscopy) measurements, it was shown that, during the first discharge, the cubic phase undergoes a pure conversion process (NiP2 + 6 Li+ + 6e- f Ni° + 2Li3P) as opposed to a sequential insertion-conversion process for monoclinic NiP2. Such a different behavior rooted in subtle structural changes was explained through electronic structure calculations. Once the first discharged is achieved, both phases were shown to react with Li through a classical conversion process. More importantly, we report a novel way to design NiP2 electrodeswith enhanced capacity retention and rate capabilities. It consists in growing the monoclinic NiP2 phase,through a vapor-phase transport process, on a commercial Ni-foam commonly used in Ni-based alkaline batteries. These new self-supported electrodes, based on chemically made interfaces, offer new opportunities to fully exploit the capacity gains provided by conversion reactions

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Matériaux
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Dates et versions

hal-00383231 , version 1 (12-05-2009)

Identifiants

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Frédéric Gillot, Simeon Boyanov, Loic Dupont, Marie-Liesse Doublet, Mathieu Morcrette, et al.. Electrochemical Reactivity and Design of NiP2 Negative Electrodes for Secondary Li-Ion Batteries. Chemistry of Materials, 2005, 17 (25), pp.6327-6337. ⟨10.1021/cm051574b⟩. ⟨hal-00383231⟩
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