利用离子液体作为结构导向剂和溶剂，用共沉淀-退火的方法成功制备了Cr³⁺掺杂的FeF₃·0.33H₂O材料。通过XRD、XPS、SEM、TEM等表征手段对不同摩尔比的Cr³⁺掺杂后的FeF₃·0.33H₂O的结构、形貌等进行了表征。结果表明，掺杂材料的晶体结构没有发生大的改变，提升了材料的电子电导率。过量的离子液体在煅烧后会在材料表面形成碳层，可以稳定材料的结构。作为锂离子电池正极材料，在1.5～4.0 V电压范围内，电化学性能测试的结果表明，Cr³⁺的掺杂会使FeF₃·0.33H₂O材料具有更好的循环稳定性和倍率性能，其中，摩尔含量为5%的样品电化学性能最好，在0.1C电流密度下，50次循环后，可逆容量为198 mAh/g，在1C的大电流密度下，比容量可达到107 mAh/g。
关键词: 正极材料 / 共沉淀法 / FeF₃ / Cr³⁺掺杂 / 锂离子电池
Abstract:
Cr³⁺-doped FeF₃·0.33H₂O material is successfully synthesised via a co-precipitation-annealing method, with ionic liquids as structure-directing agents and solvents. The structure and morphology of Cr³⁺-doped FeF₃·0.33H₂O at different molar ratios are characterized using XRD, XPS, SEM, and TEM. Results indicate that the crystal structure of the doped material remains largely unchanged, while its electronic conductivity is enhanced. Excess ionic liquid forms a carbon layer on the material surface after calcination, stabilising its structure. As a cathode material for lithium-ion batteries, electrochemical performance testing within the 1.5～4.0 V voltage range demonstrates that Cr³⁺ doping confers superior cycling stability and rate capability of FeF₃·0.33H₂O. Samples with a 5% molar ratio exhibit optimal electrochemical performance, achieving reversible capacities of 198 mAh/g after 50 cycles at 0.1C current density, and a specific capacity of 107 mAh/g at a high current density of 1C.
Keywords: cathode material / co-precipitation method / FeF₃ / Cr³⁺ doping / lithium-ion battery