Facile and Scalable Synthesis of 3.9V LiFeSO4F

Cathode materials of Li-ion batteries have been developing to achieve high energy density with superior safety for powering novel applications such as electric vehicles and enegy storage systems. With respect to this consideration, polyanion compounds such as phosphates, fluorophosphates, fluorosulfates have attracted a lot of attention because of their superior safety and high energy density. Among these F-containing compounds, LiFeSO₄F compound has been paid much attention as a promising candidate for cathode material in Li ion battery because it shows high energy density with high potential and 151 mAh/g. Especially, tripilite LiFeSO4F phase, one of polymorphs, shows much higher voltage (3.9V Vs. Li+/Li) compared to tavorite LiFePO4F phase (3.6V Vs. Li+/Li) leading to higher energy density. However, the utilization of triplite LiFeSO4F phase has been limited because of complicated synthetic process. Typically, the triplite phase is synthesized by transforming tavorite phase which is formed through topotatic process.^[2] Therefore, the key point of challenge is direct synthetic process without tavorite phase transformation. Triplite phase is also more stable than tavorite phase with respect to themodynamic condisderation.^[3]

In this presentation, we will discuss the key experimental parameters to obtain triplite phase without going through the phase transfroamtion of tavorite phase and will present the electrochemical properties of the triplite phase obtained by fascile and scalable process.

References

[1] N. Recham &Tarascon, Nature Material 9 (2010) 68 - 74 

[2] P. Barpanda &Tarascon, Nature Material 10 (2011) 772-779 

[3] A. V. Radha & A. Navrotsky, J. Mater. Chem, (2012), 22, 24446 - 24452