High Energy Density Carbon Nanotube-Based Supercapacitors

Abstract

We have developed supercapacitors utilizing electrodes made of binder-free carbon nanotube (CNT) / activated carbon (AC) composites. Due to the absence of organic binder our supercapacitors exhibit a significantly higher volumetric capacitance of ~20 F/cc compared to conventional supercapacitors while maintaining low resistance. This results in higher energy in the same package or smaller, more compact package size (lower volume) with same energy. Our cells pass 1,000 hour float tests at 2.7V between -35°C and 70°C, as well as high voltage operation at 3V and 70°C. Operation for 100,000 continuous cycles at 85°C was also achieved. Flat format supercapacitor pouch cells > 100 F have been demonstrated that can be integrated into automotive panels for autonomous power. Notable features of our CNT/AC composite supercapacitor technology include: Scalable R2R coating of CNT/AC electrodes without additives. Option of water-based process with no solvent recoveryBinder-free CNT/AC electrodes provide 20% higher energy density than conventional AC-based electrodes (50% higher energy density at 3V)CNT/AC supercapacitor technology is 100% packaging agnosticFabrication of 18650 EDLC cells rated at ~ 100 F demonstrated, and pouch cells rated at ~ 350 F demonstrated The flat pouch-cell format allows installation in automotive panels as power sources for emergency door lock/unlock applications. Figure 1