Confined iron fluoride@CMK-3 nanocomposite as an ultrahigh rate capability cathode for Li-ion batteries

A facile and advanced architecture design of FeF₃·0. 33H₂O impregnated CMK-3 nanocomposite (FeF₃·0. 33H₂O@CMK-3) is presented. In the FeF₃·0.33H ₂O@CMK-3 nanocomposite, mesoporous carbon CMK-3 can provide enough passageways for electron and Li⁺ transport to the confined nanosized FeF₃·0.33H₂O. The intimate conductive contact between the FeF₃·0.33H₂O nanoparticles and the carbon framework not only provides an expressway of electron transfer for Li⁺ insertion/extraction but also suppresses the growth and agglomeration of FeF₃·0.33H₂O during the crystallization process. As expected, the nanostructured materials exhibit impressive rate capability and excellent cyclicity. Remarkably, even under an ultrahigh charge/discharge rate of 50 C (the charge or discharge process takes a mere 72 s), the confined FeF₃·0.33H₂O@CMK-3 still shows a high specific capacity of 78 mAh g^-1. By combining confined nanosized active material, high electron conductivity, and open framework, the FeF₃·0.33H₂O@CMK-3 nanocomposite demonstrates excellent high-rate capability and good cycling properties. A mesoporous FeF₃·0.33H₂O@CMK-3 nanocomposite is designed via a facile nanocasting technique using CMK-3 as a conductive matrix. By combining confined nanosized FeF₃·0.33H₂O, high electron conductivity, and open framework, the FeF₃·0.33H ₂O@CMK-3 nanocomposite demonstrates impressive ultrahigh-rate capability (78 mAh g^-1 at 50 C) and excellent cycling properties (retaining over 97% of the initial capacity after 140 variational cycles).