Crystal structure and electrochemical study of A(Fe 1-xM x)SO 4F (A = Li/Na; M = Co/Ni/Mn) fluorosulphates prepared by low temperature synthesis

In the quest for next-generation cathodes for Li-ion batteries, our group has come up with a novel metal fluorosulphate material LiFeSO 4F tying the benefits of sulphate polyanions with fluorine chemistry. It delivers excellent capacity (∼140 mAh/g) involving a 3.6 V Fe +2/+3 redox plateau along with good rate capability and capacity retention. Following, we have discovered various isostructural LiMSO 4F compounds (M = Co, Ni, Mn) as well as sodium-based metal fluorosulphate NaMSO 4Fcompounds (M = Fe, Co, Ni, Mn). All these novel compounds have been prepared using low temperature synthesis, not exceeding 300°C and their structures have been solved. In an effort to examine and improve the electrochemical properties of electrochemically active AFeSO 4F (A = Li, Na) homologues, we hereby investigate the synthesis, crystal structure, conductivity and electrochemical behaviour of 3d-metal substituted fluorosulphates A(Fe 1-xM x)SO 4F (A = Li, Na; M = Co, Ni, Mn) compounds. ©The Electrochemical Society.