F127/PDA dual-assisted fabricating high dispersed Ge nanoparticles /N-doped porous carbon composites with efficient lithium storage
Haiwei Yu, Mingyue Gao, Ming Zhou, Hui Gu, Xiang‐Jun Zheng, Xingmei Guo, Yuanjun Liu, Fu Cao, Qinghong Kong, Junhao Zhang
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 is attributed to that the synergistic effect between three-dimensional carbon network structure and Ge nanoparticles, which provides stable mechanical structure and rich redox sites, suppressing volume expansion and accelerating the electrochemical reaction kinetics.