F127/PDA dual-assisted fabricating high dispersed Ge nanoparticles /N-doped porous carbon composites with efficient lithium storage

Abstract

Nanocrystallization and carbon composite are effective methods to solve the mechanical instability and low conductivity of Ge-based anode materials. In this work, a meaningful phenomenon is discovered that F127 can effectively disperse GeO2 polycrystalline particles, which facilitates the formation of Ge nanoparticles embedded in N-doped carbon (Ge/N-C) composites. Polydopamine (PDA) has cross-linking effect, effectively alleviating the reaggregation of GeO2 nanoparticles, and its derived N-doped carbon ensures the uniform dispersion and independent structure of Ge nanoparticles. When assessed as anode material for lithium-ion batteries (LIBs), Ge/N-C composites exhibit a high discharge capacity of 1323 mA h g−1 in the second cycle at 0.2 A g−1 and 981 mA h g−1 after 100 cycles, with a capacity retention rate of 74%. Additionally, the composites show high-rate capability of 959 mA h g−1 at 2 A g−1. The excellent lithium storage performance is attributed to that the synergistic effect between three-dimensional carbon network structure and Ge nanoparticles, which provides stable mechanical structure and abundant redox sites, suppressing volume expansion and accelerating the electrochemical reaction kinetics.

Keywords

• F127/PDA dual-assisted strategy
• Ge nanoparticles
• Nitrogen-doped porous carbon
• Buffering volume expand
• Lithium-ion batteries