Journal
JOURNAL OF POWER SOURCES
Volume 506, Issue -, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.jpowsour.2021.230103
Keywords
Supercapacitors; Energy density; Power density; Ultrafast-charging; Semi-graphitic interconnected hierarchical porous carbon
Funding
- National Natural Science Foundation of China [21867015, 51462020]
- Natural Science Foundation of Gansu, China [20JR10RA155]
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This research successfully improves the energy density of aqueous supercapacitors using a composite alkaline electrolyte and hierarchical porous carbon nanosheet electrode material, ensuring high power density. The assembled supercapacitor demonstrates reliable ultrafast-charging performance.
How to simultaneously achieving high energy and power density is a key challenge for ultrafast-charging supercapacitors. Herein, a composite alkaline electrolyte with widened operation voltage is utilized to improve the energy density of aqueous supercapacitors, while a well-designed semi-graphitic hierarchical porous carbon nanosheet electrode material is prepared to ensure the high power density by effectively alleviating polarization during the charging/discharging process. The symmetrical supercapacitor built by the above electrode material and electrolyte exhibits both high energy and power density, which can reliably work at 1.3 V and display high capacitance retention of 85.0% at 50 A g(-1). A high energy density of 12.2 Wh kg(-1) is achieved at 203 W kg(-1) and more than 85.0% of energy density is retained even when the power density increases by ca 100-fold (10.2 Wh kg(-1) at 20.4 kW kg(-1)). The assembled supercapacitor can be charged to 100% within 3.4 s at 20 A g(-1) and then deliver a specific capacitance of 48.9 F g(-1) at a small discharging current density of 0.5 A g(-1), which value reaches 93.1% of the specific capacitance recorded by using the same charging/discharging current density (0.5 A g-(1)), indicating the reliable ultrafast-charging performance in practical application.
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