Confined germanium nanoparticles in an N-doped carbon matrix for high-rate and ultralong-life lithium ion batteries

Abstract

In this study, a relatively simple and direct method is used to prepare germanium nanoparticles (Ge NPs) embedded in the pore tunnels of an N-doped mesoporous carbon matrix. In the Ge/CMK-3 nanocomposite, the highly ordered porous structure and large pore volume guarantee a sufficient Ge loading and buffer the large volume changes of Ge during the discharge/charge cycles. More specifically, the mesoporous carbon matrix can supply sufficient pathways for Li⁺ and electron transport to the encapsulated nanometer-sized Ge, as well as restrain the agglomeration and growth of Ge during the crystallization process. Accordingly, the electrode of Ge/CMK-3 attained a capacity as high as 755.7 mA h g⁻¹ at 500 mA g⁻¹ after 420 cycles with a capacity retention of 93.3% based on the 11th cycle. The study shows that the electrochemical properties of Ge/CMK-3 are significantly improved compared to that of the bulk Ge anode, and it demonstrates that Ge/CMK-3 could potentially show promise as an anode material for energy storage.