Novel and scalable solid-state synthesis of a nanocrystalline FeF₃/C composite and its excellent electrochemical performance

Abstract

A scalable solid-state reaction is presented to synthesize an FeF3 cathode material by using PTFE as a source of both fluorine and carbon. The method yields nanocrystalline FeF3/C showing excellent electrochemical performance even without any conducting additive. This method can be utilized for engineering MFs' properties and developing other fluorine compounds.

Mn-Doped Fe1–xMnxF3·0.33H2O/C Cathodes for Li-Ion Batteries: First-Principles Calculations and Experimental Study

“…Among fluoride-based cathodes, iron trifluoride, appears to be unique as a potential candidate cathode owing to its high theoretical capacity, high operating voltage, environmental friendliness, and low cost. 14,15 As a polymorph of iron fluoride, FeF 3 •0.33H 2 O has a unique hexagonal cavity composed of six octahedrons by cornersharing, where H 2 O molecules exist in the center of cavities, which are suitable for intercalation and deintercalation of Liions. In addition, the existence of crystal water can stabilize the structure and decrease the band gap as well as enhance the electronic conductivity.…”

“…Nowadays, Li-ion batteries (LIBs) are receiving increasing attention in a wide range of applications from portable electronics to transportation (such as hybrid electric vehicles and pure electric vehicles) for their advantages in efficiency, no memory effect, environmental benignity, and so forth. − Although several breakthroughs have been made in the last decades, the reversible specific capacities of commercial cathode materials (e.g., LiCoO 2 , LiFePO 4 ) are still too low to satisfy the ever-growing demands for advanced LIBs with high energy/power density. , Fortunately, transition-metal fluorides on the basis of the conversion reaction have triggered worldwide interest as alternative cathode materials for LIB application because of their relatively high voltage plateau and large theoretical capacities. , For instance, CuF 2 has a working potential of 3.55 V and a theoretical capacity of 528 mA h g –1 , , FeF 3 (2.74 V, 712 mA h g –1 ), , FeF 2 (2.66 V, 571 mA h g –1 ), , and so forth. Among fluoride-based cathodes, iron trifluoride, appears to be unique as a potential candidate cathode owing to its high theoretical capacity, high operating voltage, environmental friendliness, and low cost. , As a polymorph of iron fluoride, FeF 3 ·0.33H 2 O has a unique hexagonal cavity composed of six octahedrons by corner-sharing, where H 2 O molecules exist in the center of cavities, which are suitable for intercalation and deintercalation of Li-ions. In addition, the existence of crystal water can stabilize the structure and decrease the band gap as well as enhance the electronic conductivity.…”

Reversible control of magnetism: on the conversion of hydrated FeF3 with Li to Fe and LiF

“…41 While the insertion reaction is reported to be reversible, the conversion reaction leads to accelerated degradation. 42 These two mechanisms were independently monitored and Fig. 1 shows the evolution of the magnetic moment with cycling in the insertion regime between 2 and 4.5 V vs. Li + /Li.…”

High-Performance Cathode Material of FeF3·0.33H2O Modified with Carbon Nanotubes and Graphene for Lithium-Ion Batteries

“…One key challenge is developing high-performance electrode active materials, and the cathode material is a vital factor for improving the electrochemical properties of LIBs, including the specific capacity, cycling capability, rate capability, etc. [2, 3]. Commercialized cathode materials, such as LiCoO 2 [4], LiMn 2 O 4 [5], and LiFePO 4 [6], suffer from low theoretical capacities due to the intercalation reaction involving only a single electron reaction, which cannot satisfy the demands of EVs.…”