Lithiation phase behavior and electrochemical properties of silicon nanoparticles with tunable sizes

초록

This study investigates how particle size and structural phase affect the electrochemical performance of silicon nanoparticle anodes in lithium-ion batteries. Si particles ranging from 10 to 100 nm were synthesized via a radio-frequency thermal plasma process with adjustments to control size and crystallinity. Structural analysis confirmed that smaller particles were mostly amorphous, whereas larger particles retained crystalline domains. Electrochemical tests indicate that 100-nm particles exhibit the highest initial charge capacity and Coulombic efficiency, whereas 10-nm particles show the lowest. Ex-situ X-ray diffraction analysis revealed a strong correlation between particle size and structural phase: Amorphous-rich particles formed Li12Si7, whereas crystalline-rich particles formed Li15Si4. The 50-nm particles formed Li12Si7 and exhibited improved cycling performance than the 100-nm particles. These results highlight the importance of particle size and phase composition optimization for a balance between the capacity, efficiency, and durability of Si-based anodes.

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