CoFe2O4@C复合纳米纤维膜作为自支撑锂离子电池负极

CoFe2O4@C composite nanofiber films as self-standing anodes for lithium-ion batteries

为了提高CoFeO作为锂离子电池负极材料的综合电化学性能,将其与高导电性的碳纤维进行复合。通过静电纺丝及低温碳化制备了均匀镶嵌CoFeO纳米颗粒的碳纳米纤维(CoFeO@CNFs)柔性复合膜,使用XRD、TG、Raman、SEM、TEM、CV、GCD和EIS等对复合物进行表征,着重研究了CoFeO含量对其储锂性能的影响。该复合膜直接用作自支撑锂离子电池负极时表现出较好的电化学性能。CoFeO的引入显著提高了碳纳米纤维膜的电化学性能,随着CoFeO含量的增加,CoFeO@CNFs电极的比容量先增加后减小,CoFeO含量约为33.3%(w/w)的CoFeO@CNFs-3电极具有最高的比容量和更好的循环及倍率性能。在0.1 A·g的电流密度下,充放电循环100圈后比容量为611.4 mA·h·g-1,相对第二圈的容量保持率为94%;当电流密度增大到2 A·g时,其比容量仍有353.6 mA·h·g。CoFeO@CNFs-3更好的电化学性能主要归因于高电化学活性CoFeO和高导电纳米碳纤维的恰当结合及更好的协同效应。

In order to improve the comprehensive electrochemical performance of the CoFeOelectrode material for lithium-ion batteries(LIBs), the CoFeOis integrated with highly conductive carbon materials. Flexible carbon nanofibers uniformly embedded with CoFeOnanoparticles(CoFeO@CNFs) composite films were synthesized by an electrospinning and subsequent low-temperature carbonization process, and were characterized by XRD, TG,Raman, SEM, TEM, CV, GCD and EIS. The influence of CoFeOcontent on the lithium storage performances of CoFeO@CNFs composites was investigated in detail. It is found that the as-prepared composite films directly used as self-standing anodes in lithium ion batteries exhibit good electrochemical properties. The incorporation of CoFeOnanoparticles into CNFs can significantly improve their electrochemical performances, and the specific capacities first increase and then decrease with increasing CoFeOcontent in CoFeO@CNFs, in which the CoFeO@CNFs-3 electrode with about 33.3%(w/w) CoFeOpresents an optimal specific capacity as well as better cycle stability and rate capability. The CoFeO@CNFs-3 electrode delivers a high reversible specific capacity of 611.4 mA·h·gafter 100 charge/discharge cycles at the current density of 0.1 A·g, corresponding to a capacity retention of 94% relative to the capacity of the second cycle. Moreover, even at a high current density of 2 A·g, the specific capacity still remains at 353.6 mA·h·g. The superior performance for CoFeO@CNFs-3 is mainly attributed to the proper combination and highly synergistic effect of electrochemically active CoFeOand high conductive CNFs matrix.