State Key Laboratory of Chemical Resource Engineering, Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology , Beijing, People's Republic of China.
ACS Appl Mater Interfaces. 2014 Dec 10;6(23):21223-9. doi: 10.1021/am506236n. Epub 2014 Nov 25.
Application of iron fluoride, a promising candidate of cathode materials for lithium ion batteries, is being hindered by its poor electrochemical performance caused by low electronic conductivity and large volume change. Design of carbon-encapsulated transitional metal compounds (including fluoride, oxide, sulfide, etc.) structure is one of the most effective strategies in improving their lithium-ion storage performance. In this work, we successfully synthesize for the first time carbon-nanotube-encapsulated FeF2 nanorods via a facile in situ co-pyrolysis of ferrocene and NH4F. This kind of core/shell carbon nanotube/FeF2 nanorod exhibits better cyclic stability and rate-performance used as cathode materials. Better electrochemical performance of the nanorods should be attributed to the protection of the carbon shell because, experimentally, it is observed that outer carbon shells suffer from high internal stress during Li-ion insertion but efficiently keep the nanorods in the one-dimensional morphology and make nanorods a good electrical contact with the conductive carbon black. This work not only prepares high-performance core/shell carbon/iron fluoride cathode materials, but should also open a facile pathway for design of various novel nanostructures of other metal fluoride/carbon core/shell structures for future lithium-ion batteries.
应用氟化铁作为锂离子电池的阴极材料，由于其电子电导率低和体积变化大，导致电化学性能较差。设计碳包覆过渡金属化合物（包括氟化物、氧化物、硫化物等）结构是提高其锂离子存储性能的最有效策略之一。在这项工作中，我们首次通过简单的原位共热解二茂铁和 NH4F 成功合成了碳纳米管封装的 FeF2 纳米棒。这种核/壳碳纳米管/FeF2 纳米棒作为阴极材料具有更好的循环稳定性和倍率性能。纳米棒具有更好的电化学性能，应该归因于碳壳的保护，因为实验观察到，在外层碳壳在锂离子嵌入过程中会受到高内应力的影响，但它有效地保持了纳米棒的一维形态，并使纳米棒与导电炭黑保持良好的电接触。这项工作不仅制备了高性能的核/壳碳/铁氟化物阴极材料，而且还为设计用于未来锂离子电池的其他金属氟化物/碳核/壳结构的各种新型纳米结构开辟了一条简便的途径。
