Pseudocapacitance-Enhanced Storage Kinetics of 3D Anhydrous Iron (III) Fluoride as a Cathode for Li/Na-Ion Batteries
Tao Zhang, Yan Liu, Guihuan Chen, Hengjun Liu, Yuanyuan Han, Shuhao Zhai, Leqing Zhang, Yuanyuan Pan, Qinghao Li, Qiang Li
Abstract
Transition metal fluoride (TMF) conversion cathodes, with high energy density, are recognized as promising candidates for next-generation high-energy Li/Na-ion batteries (LIBs/SIBs). Unfortunately, the poor electronic conductivity and detrimental active material dissolution of TMFs seriously limit the performance of TMF-LIBs/SIBs. A variety of FeF3-based composites are designed to improve their electrochemical characteristics. However, the storage mechanism of the conversion-type cathode for Li+ and Na+ co-storage is still unclear. Here, the storage mechanism of honeycomb iron (III) fluoride and carbon (FeF3@C) as a general cathode for LIBs/SIBs is analyzed by kinetics. In addition, the FeF3@C cathode shows high electrochemical performance in a full-cell system. The results show that the honeycomb FeF3@C shows excellent long-term cycle stability in LIBs (208.3 mA h g−1 at 1.0 C after 100 cycles with a capacity retention of 98.1%). As a cathode of SIBs, the rate performance is unexpectedly stable. The kinetic analysis reveals that the FeF3@C cathode exhibit distinct ion-dependent charge storage mechanisms and exceptional long-durability cyclic performance in the storage of Li+/Na+, benefiting from the synergistic contribution of pseudocapacitive and reversible redox behavior. The work deepens the understanding of the conversion-type cathode in Li+/Na+ storage.