Preparation of Nanoporous Si by Dealloying in Metallic Melt and Its Application for Negative Electrode of Lithium Ion Battery

Three dimensional nanoporous Si with controlled pore and ligament size was prepared by immersing Mg-Si alloy precursor in Bi metal bath. The miscible nature of Bi-Mg and immiscible one of Bi-Si caused selective dissolution of Mg from Mg-Si precursor in Bi melt, leaving interconnected ligaments enriched by Si element. The lithium ion battery negative electrode made from the developed nanoporous Si exhibited larger capacity and longer cycle life compared with nanoparticle Si based electrode. By controlling amount of Li insertion, volume expansion of Si can be limited below pore volume. In such an operation condition, volume expansion is accommodated within pores thus electrode degradation was suppressed resulting in the prolonged cycle life of the electrode.