Enhanced charge storage of Na3FeF6 with carbon nanotubes for lithium-ion batteries

Transition metal fluoride Na3FeF6 was investigated as positive electrode materials for lithium-ion batteries. The Na3FeF6 and Na3FeF6/CNTs composites were prepared by a simple liquid phase method and the electrochemical performances were obtained by charge-discharge measurements, CV and EIS test. The initial specific capacities of Na3FeF6/C and Na3FeF6/CNTs are 458 mAh g− 1 and 428 mAh g− 1, respectively, while the reversible capacity of Na3FeF6/CNTs is 296.7 mAh g− 1, 1.47 times as much as that of Na3FeF6/C, 201.7 mAh g− 1 after 60 cycles. The Na3FeF6/CNTs electrode has a lower SEI film resistance, Schottky contact resistance and charge transfer resistance than Na3FeF6/C electrode from the fitting results, which can reduce the internal resistance and improve the electrochemical activity of Na3FeF6.