Unusual carbon nanomesh constructed by interconnected carbon nanocages for ionic liquid-based supercapacitor with superior rate capability

Abstract

The exploration of various porous nanocarbon materials with an extraordinary electrochemical capacitive performance in ionic liquid (IL) electrolytes is urgently needed for development of the next-generation energy storage devices. Significant improvements in energy density have been achieved, however, supercapacitors with IL electrolytes usually suffer from issues related to low power density and large IR drop. Herein, we report an unprecedented carbon nanomesh that is made up of interconnected densely-packed carbon nanocages with ultrathin partially graphitic shells. The large specific surface area and well-developed mesopores combined with its unique structural features, make it a very competitive material for high-performance supercapacitor in IL electrolyte. Notably, this unique nanosheets morphology with lots of in-plane nanopores on their surface can provide fast cross-plane ion diffusion pathways, and meanwhile, the carbon nanocages with partially graphitic shells ensure the rapid electron transfer. The supercapacitor assembled with the optimized sample can deliver a high specific capacitance (up to 194 F/g at 1 A/g), superior rate capability (68% capacitance retention at 70 A/g), low IR drop (0.685 V at 70 A/g). Moreover, benefiting from the wide working voltage and high-rate capability, the energy densities can maintain at 56.1 Wh/kg even at an ultrahigh power density of 61.250 kW/kg. Strikingly, the as-assembled supercapacitor can successfully power a light-emitting diodes (LED, 2.2 V) module with 53 red LED lights demonstrating its great potential for practical applications in energy storage devices.