Carbothermal Synthesis of Nitrogen-Doped Graphene Composites for Energy Conversion and Storage Devices.

Hongwei Mi,Qianling Zhang,Xiaodan Yang,Jun Hu,Jianhong Liu

doi:10.3389/fchem.2018.00501

Abstract

Metal oxides and carbonaceous composites are both promising materials for electrochemical energy conversion and storage devices, such as secondary rechargeable batteries, fuel cells and electrochemical capacitors. In this study, Fe3O4 nanoparticles wrapped in nitrogen-doped (N-doped) graphene nanosheets (Fe3O4@G) were fabricated by a facile one-step carbothermal reduction method derived from Fe2O3 and liquid-polyacrylonitrile (LPAN). The unique two-dimensional structure of N-doped graphene nanosheets, can not only accommodate the volume changes during lithium intercalation/extraction processes and suppress the particles aggregation but also act as an electronically conductive matrix to improve the electrochemical performance of Fe3O4 anode, especially the rate capability. What's more, by etching Fe3O4@G to remove the iron-based oxide template, porous N-doped graphene composites (NGCs) were prepared and presented abundant pore structure with high specific surface area, delivering a specific capacitance of 172 F·g−1 at 0.5 A·g−1. In this way, Fe2O3 was both template and activator to adjust the pore size of graphene. And the effect of specific surface area and pore size tuned by the Fe2O3 activator were also revealed.

Highlights

Due to increasing energy and environmental demands, the utilization of energy storage devices have become a pressing essential need in both civil and military applications (Dunn et al, 2011; Etacheri et al, 2011; Chu and Majumdar, 2012; Li et al, in press)
As materials play a leading role in the research of energy storage devices, metal oxides are considered as promising materials for electrochemical energy storage and conversion devices, such as secondary rechargeable batteries(Chen et al, 2017; Cui et al, 2018; Yi et al, 2018; Zhao et al, 2018; Zheng et al, 2018), fuel cells and electrochemical capacitors (Jiang et al, 2012; Wang et al, 2012, 2016; Wu et al, 2012; Nithya and Arul, 2016)
What’ more, carbonaceous materials especially graphene, which received worldwide attention owing to its outstanding properties, shows superior performances in high-performance lithium-ion batteries due to their good conductivity and large surface areas (Behera, 2011; Yan et al, 2014)

Summary

Introduction

Due to increasing energy and environmental demands, the utilization of energy storage devices have become a pressing essential need in both civil and military applications (Dunn et al, 2011; Etacheri et al, 2011; Chu and Majumdar, 2012; Li et al, in press). What’s more, by etching Fe3O4@G to remove the iron-based oxide template, porous N-doped graphene composites (NGCs) were prepared and presented abundant pore structure with high specific surface area, delivering a specific capacitance of 172 F·g−1 at 0.5 A·g−1. The unique two-dimensional graphene nanosheets can promote rapidly electron transport and maintain the structural integrity during the electrochemical lithium insertion/extraction reaction so as to enhance the rate capability of the prepared composite electrode.

Results

Conclusion