Amorphous FeF3/C nanocomposite cathode derived from metal-organic frameworks for sodium ion batteries

Amorphous FeF3/C nanocomposites, where FeF3 nanoparticles are intimately anchored into a highly-graphitized porous branch-like carbon framework, have been successfully designed and fabricated from the carbonized Fe-MOFs by a novel vapor-solid fluoridation reaction and dehydration reaction. Compared to the FeF3/C nanocomposites obtained from the precursors at various carbonization conditions, the one carried out at 700 degrees C for 3 h exhibits the most outstanding comprehensive sodium ion storage performance. It can deliver 302, 146, 73 mA h g(-1) discharge capacities at current densities of 15, 150, 1500 mA g(-1), respectively, exhibiting an excellent sodium ion capacity and rate performance. Moreover, it displays a good cycling performance with a discharge capacity of 126.7 mA h g(-1) at 75 mA g-1 after 100 cycles. The outstanding electrochemical features of the FeF3/C nanocomposites could be attributed to its amorphous structure and highly-graphited porous carbon framework, which is beneficial to the ionic and electronic transport and the reaction kinetics of electrode materials.