硅/碳纳米纤维复合材料的制备及电化学性能研究

Preparation and Electrochemical Properties of Silicon/Carbon Nanofiber Composite Materials

摘要: 硅作为一种先进的锂离子电池转换型负极材料，由于其较高的理论容量和储量丰富而被广泛研究。然而，其实际应用受限于较差的本征导电性和严重的体积变化。在本研究中，通过静电纺丝法合成了具有网状结构的硅/碳纳米纤维复合材料(Si@CNFs)来解决此问题。在0.1 A g⁻¹的电流密度下，Si@CNFs首次放电比容量为1094.2 mAh g⁻¹；循环50次后，容量保留为847.4 mAh g⁻¹；在1 A g⁻¹的大电流密度下循环200次后，仍具有303.3 mAh g⁻¹的容量保留，表现出优异的循环稳定性。优异的性能表现归因于独特的网状结构为锂离子的快速传输提供了通道，硅颗粒被碳层包覆有助于抑制充放电过程中的体积膨胀，以及提高复合材料的整体导电性。

Abstract: Silicon has been widely studied as an advanced conversion anode material for lithium-ion batteries due to its high theoretical capacity and abundant reserves. However, its practical application is limited by poor intrinsic conductivity and severe volume changes. In this study, silicon/carbon nanofiber composites (Si@CNFs) with a reticulated structure were synthesized by electrostatic spinning to address this issue. At a current density of 0.1 A g⁻¹, the first discharge specific capacity of Si@CNFs was 1094.2 mAh g⁻¹; after 50 cycles, the capacity retention was 847.4 mAh g⁻¹; and after 200 cycles at a high current density of 1 A g⁻¹, it still possessed a capacity retention of 303.3 mAh g⁻¹, which exhibited excellent cycling stability. The excellent performance is attributed to the unique mesh structure that provides a channel for the rapid transport of lithium ions, and the coating of silicon particles with a carbon layer that helps to inhibit the volume expansion during charging and discharging as well as to improve the overall electrical conductivity of the composites.