The electric double layer capacitors (EDLCs) are attractive sources of energy for portable electronics, electric vehicles, and intelligent power networks. EDLC electrode materials should have a high surface area for charge accumulation and a porous structure for efficient electrolyte access. Two morphological porous carbon nanosheet materials (two-dimensional mesoporous hexagonal carbon nanosheets and three-dimensional hierarchical porous carbon nanosheets) were fabricated on Mg(OH)2 substrates through a one-step chemical vapor deposition (CVD) approach. In this process, the Mg(OH)2 serves multiple functions: including graphitization catalyst, morphology template, and pore-forming agent. Acetylene reacts with the magnesium hydroxide to form magnesium acetylide, which transforms back to magnesium hydroxide and acetylide anions through a reaction with steam. This leads to the growth of graphitic carbon. The formation of mesopores in the nanosheets is a result of H2O from the thermal decomposition of the Mg(OH)2 templates. The templated carbon materials were characterized by nitrogen physisorption, Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, cyclic voltammetry, and galvanostatic charge-discharge measurements. The templated carbon nanosheets with micropore and mesopore nanostructures have high surface areas ranging from 1323 to 1978 m2 g-1. Symmetrical electrochemical double-layer capacitors (EDLCs) were fabricated and demonstrated the highest specific capacitance of 203 F g-1 at 5 mV/s using 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl)imide (EMIM-TFSI) as electrolyte. The energy density was 86 Wh kg-1, and a power density up to 16.57 kW kg-1 was observed. After 5000 charge-discharge cycles at 10 A g-1, the supercapacitor retained 90% of its initial capacitance. This illustrates the great stability of the templated carbon sheets for supercapacitors.

Magnesium hydroxide templated porous carbon nanosheets for supercapacitors

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.