Dr. Kwun Nam Hui

Institute of Applied Physics & Materials Engineering, University of Macau, Macau SAR, China

Topic: Rational Design of Metal Oxides for High-Performance Supercapacitor

The stringent requirements for reliable supercapacitors have increased because of their rapidly growing commercial markets for electronic devices. Supercapacitors can be divided into two types based on their charge storage mechanism: electrical double layer capacitors (EDLCs) and pseudocapacitors. EDLCs typically use carbon-based electrodes such activated carbon, carbon nanotube, and graphene for charge storage through electrostatic accumulation of surface charge. Pesudocapacitors store energy in rapid fast reversible Faradaic reactions at the surface, intercalation, or adsorption, resulting in higher energy densities [5, 6]. However, the intrinsically poor electrical conductivity and insufficient number of electrochemically active sites of transition-metal oxides hamper their wide application in high-performance supercapacitors. The demand for supercapacitors with favorable energy and power densities hasstimulated tremendous research interest on the exploration of novel nanostructured metal oxide electrode materials.

In this talk, several strategies, including the morphology control, core/shell architecture, and defect engineering, will be discussed to improve the electron transports, electrolyte ions diffusion kinetics, and electrical conductivity of metal oxide-based electrodes.Experimental analyses and theoretical calculations reveal that the electronic structure of metal oxides can be efficiently modulated by incorporating heteroatoms and oxygen vacancies, thereby simultaneously reducing the energy band gap and increasing electrical conductivity. In particular, the heteroatomsdoping approach is demonstrated to lower the diffusion barrier of electrolyte ions in intercalated supercapacitors.