Direct hydrofluorothermal synthesis of sodium transition metal fluorosulfates as possible Na-ion battery cathode materialsElectronic supplementary information (ESI) available: Details of the synthesis routes, structure determination and CIFs and CheckCIFs for compounds (I)-(VI). PXD patterns and SEM/EDAX data for compounds (I) and (III). Electrochemical experimental methods and galvanostatic cycling data for compounds (I) and (III). See DOI: 10.1039/c3cc38897b

Synthesis under hydrofluorothermal conditions produces new iron, manganese and vanadium fluorosulfates; these include the isomorphous Na 3 M III F 2 (SO 4 ) 2 , M = V, Mn, Fe, with a sheet-like structure formed of linked M III F 2 O 4 and SO 4 polyhedra separated by sodium ions which may be extracted electrochemically at potentials of >3.5 V. Synthesis using hydrofluorothermal conditions produces new sodium transition metal fluorosulfates, from which sodium may be extracted electrochemically.