High-performance 2.5 V aqueous asymmetric supercapacitor based on MnO₂ nanowire/hierarchical porous carbon composite

ABSTRACT

Aqueous supercapacitor shows a narrow operating voltage range because of the limitation of the water electrolysis, resulting in low energy density. In this work, a nanoporous MnO₂ entangled hierarchical porous carbon skeleton (simplified to MHPC) has been successfully prepared. Aqueous asymmetric supercapacitor has been assembled by employing the MHPC as a positive electrode, a hierarchical porous carbon skeleton (HPC) as a negative electrode, and a neutral Na₂SO₄ aqueous solution as electrolyte. The assembled asymmetric supercapacitor can be stably charged in an aqueous medium in a wide voltage range of 0–2.5 V and delivers a maximum energy density of 20.8Wh/kg at a power density of 0.25 kW/kg and 25 kW/kg at an energy density of 11.1 Wh/kg in a 1 M Na₂SO₄ aqueous solution. This strategy provides a new idea for developing high-energy supercapacitor.

KEYWORDS:

• Aqueous
• asymmetric supercapacitor
• high-performance
• porous carbon frameworks

Acknowledgements

Xin Fan thanks the financial support from Natural Science Foundation of Guangxi Province (2020GXNSFAA159015), Guangxi Key Laboratory of Optical and Electronic Materials and Devices (20KF-20), Innovation Project of Guangxi Graduate Education, and Open Funds of Key Laboratory of New Processing Technology for Nonferrous Metal & Materials of Ministry of Education (19AA-18) and Opening Project of Guangxi Key Laboratory of Calcium Carbonate Resources Comprehensive Utilization(Hezhou University) (HZXYKFKT201903). Hua Cheng thanks the support from the Basic Research Project of the Science and Technology Innovation Commission of Shenzhen (JCYJ20170817110251498), the Guangdong Special Support for the Science and Technology Leading Young Scientist (2016TQ03C919), the Guangdong Innovative and Entrepreneurial Research Team Program (2016ZT06G587), Natural Science Foundation of Guangdong Province (No. 2018B030322001), and Shenzhen Peacock Plan (No.KQTD2016022620054656), and the National Natural Science Foundation of China (NSFC21603094).

Disclosure statement

No potential conflict of interest was reported by the authors.

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Funding

This work was supported by the Natural Science Foundation of Guangxi Province [2020GXNSFAA159015].