| Abstract
| - A reversible structural phase transition induced by redox chemistry is demonstrated for a new class of anode materials for Li-ion batteries. Electrochemical Li+ exchange in the transition metal pnictides LixMPn4 implies a novel mechanism that reconciles large electrode capacity and small electrode volume change.
- The study presents a combined experimental and computational study of Li+ extraction/insertion mechanisms in cubic-fcc transition metal pnictides LixMPn4 (MPn = TiP, VP, VAs).Exhibiting high specific capacities (Cmax = 830 mA h g-1) at a potential close to 1 V, thesematerials have been recently proposed as promising negative electrode materials for Li-ionbattery. In situ XRD and first-principle electronic structure calculations including fullstructural relaxations are used to correlate the reversible structural phase transition observedin oxidation/reduction, to a loss/reconstruction of the unit cell fcc symmetry. The mechanismis rationalized in terms of a M−Pn bond contraction/elongation of the tetrahedral (MPn4)x-electronic entities, on which initial structures are built. This unusual redox-inducedmechanism occurs without any significant electrode volume change, thus solving one of themajor drawbacks of anodes.
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