Rational Design Strategy of Multicomponent Si/FeSeO_<i>x</i>@N-Doped Graphitic Carbon Hybrid Microspheres Intertwined with N-Doped Carbon Nanotubes as Anodes for Ultra-Stable Lithium-Ion Batteries

초록

Herein, an efficient synthesis approach is introduced for the fabrication of a hybrid anode consisting of porous microspheres with biphasic silicon (Si)-amorphous iron selenite (Si/FeSeOx) nanocrystals enveloped within an N-doped graphitic carbon (NGC) matrix and encased by well-grown, highly intertwined N-doped carbon nanotubes (CNTs) (Si/FeSeOx@NGC/N-CNT). Si and FeSeOx serve as the active components, contributing to the overall discharge capacity of the hybrid anode. Additionally, FeSeOx not only enhances the structural integrity of the nanostructure by channelizing the drastic volume variation of Si, but also expedites the diffusion of lithium ions, thereby promoting kinetically favored redox reactions. The NGC matrix serves as the primary pathway for efficient electron transfer within the electrode, whereas the well-grown N-CNTs network acts as a secondary pathway for subsequent electron transfer to the current collector. The porous structure achieved via selective removal of amorphous carbon ensures the smooth diffusion of charged species by shortening the effective charge diffusion length and accommodating the substantial volume changes during cycling. Correspondingly, the Si/FeSeOx@NGC/N-CNT anodes demonstrate significant enhancements in electrochemical performance, including one-order higher diffusion coefficients (approximate to 10-12 cm2 s-1), exceptional rate capability (till 30 A g-1), and extraordinary cycling stability at 0.5, 1.0, and 3.0 A g-1.

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