The supply of clean and sustainable energy is one of the most important scientific challenges in the 21st century. Most clean and sustainable options produce electricity, which requires electrical storage in order to link energy supply with energy demand. The energy densities of electrochemical energy technologies such as fuel cells and lithium batteries are low and their costs are high for transportation and stationary applications in comparison to combustion-based technologies. Fundamental research on the materials and catalysts that convert and store energy is needed to increase the performance and cost characteristics of electrochemical devices.

 

We will first discuss functionalized multiwall carbon nanotubes for high-power lithium storage. A device using these nanotubes as the positive electrode and a lithium titanium oxide as the negative electrode shows gravimetric energy ~5 times higher than conventional electrochemical capacitors, and power delivery 10 times higher than conventional lithium ion batteries.

 

The second part of this talk will focus on Li-air batteries, which has the promise to provide energy densities 3-5 times that of conventional lithium ion batteries. Unlike electrocatalysis of oxygen in aqueous electrolytes (fuel cells), the kinetics of oxygen reduction and oxygen evolution on metal and oxide surfaces in aprotic electrolytes, are nearly completely unknown, which limits Li-air battery efficiency. We will examine strong influence of catalysts on the charge and discharge potentials and efficiency of rechargeable Li‑O₂ batteries, contrast the activities of different catalysts in aprotic electrolytes with those in aqueous electrolytes, and postulate oxygen reduction and oxygen evolution reaction mechanisms.

 

Yang Shao-Horn is Gail E. Kendall Professor in the Department of Mechanical Engineering and Department of Materials Science and Engineering at MIT. She works with graduate students and postdocs on materials for electrochemical energy storage and conversion, which is centered on understanding and altering the crystal, surface and electronic structures of thin films and nanomaterials, and applying fundamental understanding to design new materials for lithium storage and electrocatalysis of small molecules such as oxygen reduction, water splitting and methanol oxidation.

 

She obtained her Ph.D. in Metallurgical and Materials Engineering from Michigan Technological University in 1998. She then worked as a staff scientist at Eveready Battery Company until 2000. She joined MIT in August 2002 after a two-year NSF International Research Fellowship at the Institute of Condensed Matter Chemistry in Bordeaux, France. Her select honors include GRC on Electrochemistry Plenary Lecture 2012; APS Spring Plenary Lecture 2011; Energy and Environmental Science Advisory Board 2011; Tajima Prize of the International Society of Electrochemistry 2008; Charles W. Tobias Young Investigator Award of the Electrochemical Society 2008; Dupont Young Faculty Award 2006; MIT Presidential Energy Research Council; Office of Naval Research Young Investigator Award 2003.