Design of hierarchical and mesoporous FeF_(3)/rGO hybrids as cathodes for superior lithium-ion batteries

Iron fluoride(FeF_(3)) is considered as a promising cathode material for Li-ion batteries(LIBs)due to its high theoretical capacity(712 mAh/g)with a 3 e-transfer.Herein,we have designed a strategy of hierarchical and mesoporous FeF_(3)/rG O hybrids for LIBs,where the hollow Fe F_(3) nanospheres are the main contributor to the specific capacity and the 2 D r GO nanosheets are the matrix elevating the electronic conductivity and buffering the volume expansion.The unique FeF_(3)/rGO hybrid can be rationally synthesized by a nonaqueous in-situ precipitation method,offering the merits of large specific surface area with rich active sites,fast transport channels for lithium ions,effective alleviation of volume expansion during cycles,and accelerating the electrochemical reaction kinetics.The Fe F_(3)/r GO hybrid electrode possesses a high initial discharge capacity of 553.9 m Ah/g at a rate of 0.5 C with 378 m Ah/g after 100 cycles,acceptable rate capability with 168 m Ah/g at 2 C,and feasible high-temperature operation(320 m Ah/g at 70℃).The superior electrochemical behaviors presented here demonstrates that the FeF_(3)/rGO hybrid is a potential electrode for LIBs,which may open up a new vision to design high-efficiency energy-storage devices such as LIBs based on transition metal fluorides.