Efficiency enhancement of N- doped carbon nanoweb/Si/Metal-Organic Framework derived carbon anode: The Role of Metal-Organic Framework loading variation

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Abstract
Silicon-based materials have attracted considerable interest in energy storage owing to their exceptionally high charge storage capacity. However, their widespread application is hindered by inherent limitations, namely substantial volumetric changes and low intrinsic conductivity during repeated charge–discharge cycles. Herein, a three-dimensional composite is fabricated, comprising well-dispersed silicon nanoparticles on an N-doped carbon nanoweb (NCWs) matrix, encapsulated by a carbonized ZIF-67 coating. This specific structural integration results in superior cycling performance through the effective accommodation of volume expansion and enhanced electron transport. Variations in the metal-organic frameworks (MOFs) precursor content significantly influence the electrochemical performance, highlighting the importance of an appropriate amount. This study systematically investigates the critical role of ZIF-67 precursor content on electrochemical performance. By adjusting the MOF content, the specific discharge capacity and the capacity retention at 0.05 A g⁻¹ reach 2453 mAh g⁻¹ and 1479 mAh g⁻¹, respectively. Employing a proper amount of MOF preserves structural integrity during prolonged cycling. Also, it delivers good cycle stability of 854 mAh g-1 even at 1 A g-1 over 500 cycles. In contrast, an insufficient amount of MOF precursor leads to capacity fading, from 765 to below 400 mAh g⁻¹ under the same conditions (at 1 A g-1 over 500 cycles). Furthermore, the rationally designed structure reduces the charge-transfer resistance from 34.6 to 7.7 Ω and yields higher and more stable coefficients of 4.089×10-11 cm2s-1 and 1.181×10-11 cm2 s-1 cm2s-1 for Li+ diffusion throughout the charge-discharge processes.

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