Development Of Redox-Active Organic Electrodes With Low-Cost Carbon Black For High-Performance Supercapacitors For Electric Vehicle Applications

Abstract

Global efforts to reduce greenhouse gas emissions, particularly CO2, have led countries to focus on decarbonizing the transportation sector. Moving towards electric vehicles (EVs) is necessary to reduce emissions, however despite EV technological advancements they have shortcomings in both performance and longevity. Supercapacitors are similar to batteries, however their ability to easily charge and discharge at much higher rates makes them excellent devices to work in tandem with batteries to advance their collective performance capabilities in EVs. Traditional metal-based supercapacitor materials remain to be high cost, non-renewable, and often environmentally toxic. On the other hand, quinones are organic materials considered as promising candidates for organic electrodes due to the redox activity, low cost, ease of structural modifications, nontoxicity, and renewability. To overcome quinone challenges with low electrical conductivity and dissolution in electrolyte, polymerizing quinones has become a popular modification. Conducting polymers (CPs) are increasing in interest as their -conjugated structures provide efficient electron transfer and good electrical conductivity. In the work of this master’s thesis, two types of materials were developed for supercapacitor applications; a polyimide made from alternating units of the quinones 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) and 2,6-diaminoanthraquinone (DAAQ) known as poly-perylene-3,4,9,10-tetracarboxydiimide-anthraquinone (PPA), and a truncated analogue of PPA comprised of PTCDA and two molecules of 2-diaminoanthraquinone (2-AAQ), termed N,N′-bis(2-anthra-quinone)]-perylene-3,4,9,10- tetracarboxydiimide (PDI-DAQ). All the original redox-active sites were retained following a facile synthesis to achieve fast multi-electron transfer mechanisms. These materials both were used to prepare composite electrodes with a low-cost carbon black (Ketjenblack) via simple and scalable preparation methods. Capacitances reached up to 377 F/g at 5 mV s-1 with a capacitance retention of 63.9% after 10,000 cycles at 100 mV/s. This work demonstrates the impressive energy storage capabilities of novel organic molecules in supercapacitors with low-cost carbon black to improve the performance of next-generation EVs.