Charge Storage Mechanisms of High Surface Area Carbides and Nitrides for Supercapacitors.

Energy Storage Systems;Supercapacitors;Early Transition Metal Carbides and Nitrides;Charge Storage Mechanisms;Chemical Engineering;Engineering;Chemical Engineering

Djire, AbdoulayeScott, Timothy ;

University of Michigan

关键词: Energy Storage Systems;    Supercapacitors;    Early Transition Metal Carbides and Nitrides;    Charge Storage Mechanisms;    Chemical Engineering;    Engineering;    Chemical Engineering;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/133247/adjire_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Supercapacitors are being developed for a variety of applications ranging from electric vehicles to portable electronic devices due to their high power densities and long cycle lifes. While the markets for supercapacitors are growing fast, they are small. To achieve greater market penetration, the energy densities for these devices will have to be increased. Efforts to achieve this require new materials that possess high capacitances and wide voltage windows. Early transition metal carbides and nitrides including VN and Mo2N are very attractive candidates given their high electronic conductivities and specific capacitances, and ability to be synthesized in high surface area form. Research described in this dissertation aimed to characterize the charge storage mechanisms for these materials as part of a strategy to fully exploit their properties. We isolated the active ions involved in the charge storage mechanisms, defined the active sites for charge storage, quantified the extent of pseudocapacitance and active ion insertion, and proposed overall charge storage mechanisms for these materials. Additionally, we demonstrated methods to remove the passivation layer, which impedes access of the electrolyte ions to the surface. Finally, we were able to increase the energy density by nearly a factor of four by using ionic liquid based electrolytes instead of aqueous electrolytes. The results presented in this dissertation contribute to the development of novel chemistries and provide a scientific basis for the design of high-energy density supercapacitors based on early transition-metal carbides and nitrides.