Article Title

One-step strategy to graphene/Ni(OH)₂ composite hydrogels as advanced three-dimensional supercapacitor electrode materials

Authors

Yuxi Xu, Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA
Xiaoqing Huang, Department of Materials Science and Engineering, University of California, Los Angeles, California 90095, USA
Zhaoyang Lin, Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA
Xing Zhong, Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA
Yu Huang, Department of Materials Science and Engineering, University of California, Los Angeles, California 90095, USA California Nanosystems Institute, University of California, Los Angeles, California 90095, USA
Xiangfeng Duan, Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA California Nanosystems Institute, University of California, Los Angeles, California 90095, USA

Keywords

graphene, Ni(OH)2, hydrogel, three-dimensional, supercapacitor, energy storage

Abstract

Graphene-based three-dimensional (3D) macroscopic materials have recently attracted increasing interest by virtue of their exciting potential in electrochemical energy conversion and storage. Here we report a facile one-step strategy to prepare mechanically strong and electrically conductive graphene/Ni(OH)2 composite hydrogels with an interconnected porous network. The composite hydrogels were directly used as 3D supercapacitor electrode materials without adding any other binder or conductive additives. An optimized composite hydrogel containing ~82 wt.% Ni(OH)2 exhibited a specific capacitance of ~1,247 F/g at a scan rate of 5 mV/s and ~785 F/g at 40 mV/s (~63% capacitance retention) with excellent cycling stability. The capacity of the 3D hydrogels greatly surpasses that of a physical mixture of graphene sheets and Ni(OH)2 nanoplates (~309 F/g at 40 mV/s). The same strategy was also applied to fabricate graphene–carbon nanotube/Ni(OH)2 ternary composite hydrogels with further improved specific capacitances (~1,352 F/g at 5 mV/s) and rate capability (~66% capacitance retention at 40 mV/s). Both composite hydrogels obtained here can deliver high energy densities (~43 and ~47 Wh/kg, respectively) and power densities (~8 and ~9 kW/kg, respectively), making them attractive electrode materials for supercapacitor applications. This study opens a new pathway to the design and fabrication of functional 3D graphene composite materials, and can significantly impact broad areas including energy storage and beyond.

Graphical Abstract

DOI

https://doi.org/10.1007/s12274-012-0284-4

Publisher

Tsinghua University Press

Recommended Citation

Yuxi Xu,Xiaoqing Huang,Zhaoyang Lin,Xing Zhong,Yu Huang,Xiangfeng Duan, One-step strategy to graphene/Ni(OH)2 composite hydrogels as advanced three-dimensional supercapacitor electrode materials. NanoRes.2013, 6(1): 65–76