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

The FeF 3 ·0.33H 2 O cathode material can exhibit a high capacity and high energy density through transfer of multiple electrons in the conversion reaction and has attracted great attention from researchers. However, the low conductivity of FeF 3 ·0.33H 2 O greatly restricts its application. Generally, carbon nanotubes (CNTs) and graphene can be used as conductive networks to improve the conductivities of active materials. In this work, the FeF 3 ·0.33H 2 O cathode material was synthesized via a liquid-phase method, and the FeF 3 ·0.33H 2 O/CNT + graphene nanocomposite was successfully fabricated by introduction of CNTs and graphene conductive networks. The electrochemical results illustrate that FeF 3 ·0.33H 2 O/CNT + graphene nanocomposite delivers a high discharge capacity of 234.2 mAh g −1 in the voltage range of 1.8–4.5 V (vs. Li + /Li) at 0.1 C rate, exhibits a prominent cycling performance (193.1 mAh g −1 after 50 cycles at 0.2 C rate), and rate capability (140.4 mAh g −1 at 5 C rate). Therefore, the electronic conductivity and electrochemical performance of the FeF 3 ·0.33H 2 O cathode material modified with CNTs and graphene composite conductive network can be effectively improved.