Ge–Si/C Nanofiber Composite with Enhanced Cyclic Stability and Rate Capability for Lithium-Ion Batteries
Hui Gu, Zhenpeng Zhu, Zhiyuan Gao, Junhao Zhang, Xingmei Guo, Yuanjun Liu, Xiang‐Jun Zheng, Qianqian Fan, Zhongyao Duan, Fu Cao, Chunsheng Li, Qinghong Kong
Abstract
To deal with the low conductivity and structural instability of the silicon (Si)-based anode, a Ge–Si/C nanofiber (Ge–Si/CNF) composite is fabricated based on different starting reaction potentials for Si and Ge with lithium and excellent conductivity of Ge. Sucrose is innovatively introduced as a spinning aid to maintain the carbon fiber structure derived from poly(vinyl alcohol) as the spinning polymer. When Ge–Si/CNFs are investigated as the anode material for lithium-ion batteries, it demonstrates excellent cyclic stability and rate capability. Specifically, the Ge–Si/CNFs anode can still retain 764.1 mA h g –1 at 0.5 A g –1 after 1000 cycles, and its capacity retention rate reaches 72.1%. Significantly, the specific capacity is 1168.7 mA h g –1 at 2.0 A g –1, which is restored to 1731.4 mA h g –1 when it is adjusted back to 0.1 A g –1 . The excellent lithium storage of Ge–Si/CNF anode is attributed to the effective release of stress during the lithiation/delithiation process because of the different starting potentials of Si and Ge. When one component is lithiated, the other one can act as a buffer matrix for improving the structural stability. Additionally, the addition of Ge and carbon fibers can speed up the transfer rate of Li + and electrons.