Hierarchical nanostructured silicon-based anodes for lithium-ion battery: Processing and performance

Abstract

Silicon anodes are promising for high energy density Li-ion batteries but are prone to capacity fading with cycles due to volume change and stress buildup leading to failure of electrodes. This study presents an innovative approach for realizing a high capacity silicon anode based on easily available metallurgical low-grade polycrystalline silicon powder. A three-step technique comprising of etching to create silicon nanofibers on particles, rapidly freezing the homogeneous mixture of Si nanofibers and superconducting carbon black in furfuryl alcohol solution, and then converting the furfuryl alcohol to carbon is used to achieve hierarchical nanostructure and improved performance. This approach ensures that the porous structure is filled with and separated by superconducting carbon black and is covered with a conformal and uniform conducting carbon coating. This approach improves the conductivity of the electrode and offers the flexibility for managing the volume expansion during lithiation and delithiation. The resultant electrode shows a reversible specific capacity of ∼778 mA h g−1 even after 200 cycles and coulombic efficiency of 99.6%.