title: A 3.90 V iron-based fluorosulphate material for lithium-ion batteries crystallizing in the triplite structure.
abstract: Li-ion batteries have empowered consumer electronics and are now seen as the best choice to propel forward the development of eco-friendly (hybrid) electric vehicles. To enhance the energy density, an intensive search has been made for new polyanionic compounds that have a higher potential for the Fe²⁺/Fe³⁺ redox couple. Herein we push this potential to 3.90 V in a new polyanionic material that crystallizes in the triplite structure by substituting as little as 5 atomic per cent of Mn for Fe in Li(Fe(1-δ)Mn(δ))SO₄F. Not only is this the highest voltage reported so far for the Fe²⁺/Fe³⁺ redox couple, exceeding that of LiFePO₄ by 450 mV, but this new triplite phase is capable of reversibly releasing and reinserting 0.7-0.8 Li ions with a volume change of 0.6% (compared with 7 and 10% for LiFePO₄ and LiFeSO₄F respectively), to give a capacity of ~125 mA h g⁻¹.
authors.affiliation: Laboratoire de Réactivité et Chimie des Solides, CNRS UMR 6007, Université de Picardie Jules Verne, 80039 Amiens, France.
authors.forename: P
authors.initials: P
authors.lastname: Barpanda
authors.forename: M
authors.initials: M
authors.lastname: Ati
authors.forename: B C
authors.initials: BC
authors.lastname: Melot
authors.forename: G
authors.initials: G
authors.lastname: Rousse
authors.forename: J-N
authors.initials: JN
authors.lastname: Chotard
authors.forename: M-L
authors.initials: ML
authors.lastname: Doublet
authors.forename: M T
authors.initials: MT
authors.lastname: Sougrati
authors.forename: S A
authors.initials: SA
authors.lastname: Corr
authors.forename: J-C
authors.initials: JC
authors.lastname: Jumas
authors.forename: J-M
authors.initials: JM
authors.lastname: Tarascon