高性能锂离子电池负极材料瓜状介孔Fe3O4/氮掺杂碳的制备及性能研究

Preparation and Performance Investigation of Melon-like Porous Fe3O4/N-C As a High Performance Anode for Lithium Ion Battery

通过简单的低温水热反应法制备了瓜状介孔Fe2O3微晶,经多巴胺聚合包覆和热处理后得到瓜状介孔Fe3O4/氮掺杂碳(N-C)复合物。将其作为锂离子电池负极材料的活性物质,组装成锂离子电池进行性能测试。瓜状介孔Fe3O4/N-C复合物展示出了较高的倍率性能(1A·g^-1电流密度下放电比容量大于770mAh·g^-1)和优异的循环稳定性能(在2A·g^-1电流密度下能够循环稳定1500圈而没有明显的容量损失),这主要得益于介孔结构和氮掺杂碳包覆双重作用。介孔结构提供了较大的活性物质与电解液接触面积,提高了锂离子扩散能力。同时为电极材料放电过程中体积膨胀提供充足的空间,提高了循环稳定性。氮掺杂碳包覆提高了电子导电能力,有利于电子快速转移,从而提高倍率性能。碳包覆也能够阻止微粒之间的相互聚集和结构塌陷,提高循环稳定性。

Melon-like mesoporous Fe2O3 microcrystals were prepared by a simple low temperature hydrothermal method.The Fe3O4/N-C composite were prepared by calcination of polydopamine coated Fe2O3.The Fe3O4/N-C composite exhibits high rate performance(the discharge capacity is more than 700 mAh·g^-1 at 1 A·g^-1)and excellent cycle stability(no obvious capacity loss after 1 500 cycles at 2 A·g^-1),which benefits from the dual effects of the mesoporous structure and N-doped carbon coating.The mesoporous structure provides high contact area between the active material and the electrolyte,which increases the diffusion ability of lithium ion.The mesoporous structure also provides enough room for volume expansion during discharge process,which enhances the cycle stability.N-doped carbon coating increases electronic conductivity,promotes electron transfer,and then improves the rate performance.Carbon coating can also prevent microparticle aggregation and structure collapse to enhance the cycle stability.