Understanding and promoting the rapid preparation of the triplite-phase of LiFeSO4F for use as a large-potential Fe cathode.
The development of new electrode materials, which are composed of Earth-abundant elements and that can be made via eco-efficient processes, is becoming absolutely necessary for reasons of sustainable production. The 3.9 V triplite-phase of LiFeSO(4)F, compared to the 3.6 V tavorite-phase, could satisfy this requirement provided the currently complex synthetic pathway can be simplified. Here, we present our work aiming at better understanding the reaction mechanism that govern its formation as a way to optimize its preparation. We first demonstrate, using complementary X-ray diffraction and transmission electron microscopy studies, that triplite-LiFeSO(4)F can nucleate from tavorite-LiFeSO(4)F via a reconstructive process whose kinetics are significantly influenced by moisture and particle morphology. Perhaps the most spectacular finding is that it is possible to prepare electrochemically active triplite-LiFeSO(4)F from anhydrous precursors using either reactive spark plasma sintering (SPS) synthesis in a mere 20 min at 320 °C or room-temperature ball milling for 3 h. These new pathways appear to be strongly driven by the easy formation of a disordered phase with higher entropy, as both techniques trigger disorder via rapid annealing steps or defect creation. Although a huge number of phases adopts the tavorite structure-type, this new finding offers both a potential way to prepare new compositions in the triplite structure and a wealth of opportunities for the synthesis of new materials which could benefit many domains beyond energy storage.
Laboratoire de Réactivité et Chimie des Solides, UMR CNRS 7314, Université de Picardie Jules Verne, 33 rue Saint-Leu, 80039 Amiens Cedex, France.
Mohamed
M
Ati
Mariyappan
M
Sathiya
Sylvain
S
Boulineau
Marine
M
Reynaud
Artem
A
Abakumov
Gwenaelle
G
Rousse
Brent
B
Melot
Gustaaf
G
Van Tendeloo
Jean-Marie
JM
Tarascon