One-Step Preparation of a Self-Standing LiFePO4 Cathode with an In Situ SiO2 Coating via Modified Coaxial Electrospinning for Advanced Lithium-Ion Batteries

LiFePO4 cathodes have gained much attention for Li-ion batteries due to their superior electrochemical and economic features. However, their practical applications are limited by poor electronic conductivity, sluggish lithium-ion diffusion, and unstable cathode/electrolyte interfaces. Conventional approaches require separate electrode fabrication and surface coating steps, increasing process complexity. Herein, a modified coaxial electrospinning method was developed to prepare a free-standing LiFePO4 cathode with a simultaneous in situ SiO2 coating. The core solution consists of LiFePO4 and polyacrylonitrile, while the shell solution consists of ethanol and tetraethyl orthosilicate. The modified coaxial electrode (CE-LFP@SiO2) exhibits a more uniform and smaller average fiber diameter (200 nm) compared to the single electrospinning electrode (E-LFP). Results confirm the formation of a thin SiO2 surface coating. The discharge capacity at 0.1 C reaches 166.3 mAh g-1, compared with 160.0 mAh g-1 for E-LFP and 150.0 mAh g-1 for a conventional LiFePO4 electrode (LFP). CE-LFP@SiO2 provides a capacity retention of 89% after 300 cycles, compared with 78 and 74% for E-LFP and LFP, respectively. The lithium-ion diffusion coefficient increases to 4.70 × 10-13 cm2 s-1, compared with 5.43 × 10-14 cm2 s-1 for LFP. This work demonstrates a simple one-step strategy for simultaneously fabricating and coating free-standing LiFePO4 cathodes.