One-Pot Synthesis of an FeS@GQDs Composite for Lithium Storage with Coal Tar Pitch as ″Natural GQDs″
Feng Shi, Quanrun Liu, Jingjie Zhang, Baolin Xing, Guangxu Huang, Jianbo Jia, Chuanxiang Zhang
Abstract
Graphene quantum dots (GQDs), a newly emerging zero-dimensional material, have achieved widespread interest in energy storage applications. However, the complicated preparation processes of GQDs involving harsh reagents/conditions, cumbersome purification procedures, or costly precursors hinder their practical use. Herein, we reveal a low-cost and eco-friendly solvothermal method to obtain an FeS@GQDs composite, with coal tar pitch (CTP) as ″natural GQDs″. When evaluated as an anode material in lithium-ion batteries (LIBs), this composite delivers an outstanding reversible capacity of 718.7 mAh g–1 over 200 cycles at 100 mA g–1; as comparison, the reversible capacity of pure FeS is only 16.3 mAh g–1 in the same situation. Furthermore, the FeS@GQDs composite shows much better rate performance and higher initial Coulombic efficiency than pure FeS. These prominent electrochemical properties of the FeS@GQDs composite profit from the successful coupling between FeS and GQDs by forming C–S–C, which provides a large specific surface area and well-developed porosity, leading to improved electrical conductivity and enhanced structure stability. In terms of energy storage, this approach is a potential way to prepare GQDs-based composites on a large scale without the expensive precursors, harsh reagents, as well as complex preparation conditions.