A Yolk-Shell Design for Stabilized and Scalable Li-Ion Battery Alloy Anodes

TLDR

Silicon is a promising lithium‑ion battery anode, yet practical use demands high capacity, long cycle life, high efficiency, and scalable fabrication. The study designs and fabricates a yolk‑shell structure to meet these requirements. The yolk‑shell is produced at room temperature without special equipment, encapsulating commercial Si nanoparticles in thin carbon shells with void space that accommodates volume expansion and stabilizes the solid‑electrolyte interphase. The resulting electrode delivers ~2800 mAh g⁻¹ at C/10, retains 74 % capacity after 1000 cycles, and achieves 99.84 % Coulombic efficiency.

Abstract

Silicon is regarded as one of the most promising anode materials for next generation lithium-ion batteries. For use in practical applications, a Si electrode must have high capacity, long cycle life, high efficiency, and the fabrication must be industrially scalable. Here, we design and fabricate a yolk-shell structure to meet all these needs. The fabrication is carried out without special equipment and mostly at room temperature. Commercially available Si nanoparticles are completely sealed inside conformal, thin, self-supporting carbon shells, with rationally designed void space in between the particles and the shell. The well-defined void space allows the Si particles to expand freely without breaking the outer carbon shell, therefore stabilizing the solid-electrolyte interphase on the shell surface. High capacity (∼2800 mAh/g at C/10), long cycle life (1000 cycles with 74% capacity retention), and high Coulombic efficiency (99.84%) have been realized in this yolk-shell structured Si electrode.