Enhancing the Performance of a Self-Standing Si/PCNF Anode by Optimizing the Porous Structure.

Embedding silicon nanoparticles into carbon nanofibers is one of the effective methods to fabricate a self-standing and binder-free Si-based anode material for lithium-ion batteries. However, the sluggish Li-ion transport limits the electrochemical performance in the regular strategies, especially under high rate conditions. Herein, a kind of silicon nanoparticle in porous carbon nanofiber structures (Si/PCNFs) has been fabricated through a facile electrospinning and subsequent thermal treatment. By adjusting the mass ratio to 0.4:1, a Si/PCNF anode material with an effective Li+-migration pathway and excellent structural stability can be obtained, resulting in an optimal electrochemical performance. Although increasing the mass ratio of PEG to PAN further can lead to a larger pore size and can be beneficial to Li+ migration, thus being profitable for the rate capacity, the structural stability will get worse at the same time as more defects will form and lead to a weaker C-C binding, thus decrease the cycling stability. Remarkably, the rate capacity reaches 1033.4 mA h g-1 at the current density of 5 A g-1, and the cycling capacity is 933.2 mA h g-1 at 0.5 A g-1 after 200 cycles, maintaining a retention rate of 80.9% with an initial coulombic efficiency of 83.37%.