Preparation and Properties of Chitosan Based N-doped Carbon Coated FeF₃ as Cathode Material for Lithium Ion Batteries

To address the challenges of easy reduction and ablation in the preparation of high-performance N-doped carbon coated FeF₃ cathode materials using organic polymer materials, a preparation strategy combining H₂O₂ oxidation and freeze-drying was proposed. A nitrogen doped carbon coated porous FeF₃ composite material was prepared at pH 1.8 using Fe(NO₃)₃ as the iron source and foaming agent, and chitosan as the N and C coating raw materials. The electrochemical properties of the material as a positive electrode material for lithium-ion batteries were studied. The results showed that the introduction of chitosan in the precursor solution preserved the wrapping effect of chitosan fibers in the composite material; The high-temperature O₂ direct oxidation method can cause ablation and structural collapse of chitosan porous fibers. During the fluorination process after carbonization, a hydrothermal synthesis method combining H₂O₂ oxidation and NH₄HF₂+NaH₂PO₄ fluorination is used to maintain the high valence state of Fe element in N-doped carbon coated FeF₃ composite material, thereby enabling it to have an initial capacity of 208 mAh/g and good cycling performance in the charge discharge range of 4.5~2.0 V. This method can effectively utilize the advantages of natural polymer fibers such as chitosan to prepare highly active porous FeF₃ cathode materials. The strategy proposed in this study is simple and effective, and has guiding significance for the preparation of various N-doped carbon coated composite materials.