From Fundamental Understanding Towards Materials Design of High Energy Battery Materials

Research Interests:

Electrochemical energy conversion and storage is critical for vehicle electrification and storing clean energy from intermittent sources (i.e. wind, solar) on the grid. Towards these goals, my work as a doctoral student has encompassed the broad spectrum of stages necessary for technological innovation: (1) developing new tools to discover fundamental understandings, (2) designing and synthesizing unique materials to address intrinsic failure modes, and (3) patenting the technology for real world applications.

As a doctoral student, I have developed [1] and patented [2] a novel materials design approach that enables silicon to cycle as a lithium-ion battery anode with over four times the theoretical capacity of commercial graphite (372 mAh g^-1). Using in situ transmission electron microscopy (TEM), I showed that a conformal graphene cage surrounding the silicon is electrically conductive and mechanically robust enough to overcome the dramatic failure modes (i.e. particle rupture, moving interface) of silicon during battery operation. This work is important because it demonstrated for the first time that fractured particles could still be recharged in a battery, something that the battery community believed to be previously impossible. Furthermore, the concept of a conformal graphene coating shows that simple physical mixing of two materials may be insufficient to achieve the desired properties of a composite materials system.

Looking beyond silicon, I established strategies to investigate fundamental aspects of pure lithium metal, which can potentially enable batteries with energy density approaching that of gasoline. Previous techniques were unable to study lithium metal at the nanoscale due to its extreme reactivity to the ambient environment and sensitivity to the electron beam. Using environmental [3] and cryogenic [4] TEM techniques that I developed, my research revealed the nanoscale corrosion behavior and detailed crystallography of lithium metal dendrites. The new insights guided the design of a protective nitride layer that enabled improved cycling stability of lithium metal. My results represent a simple but telling demonstration of the practical applications that can be initiated by fundamental studies on reactive battery materials. These newly developed techniques open up many excellent opportunities for future scientific discovery and invention.

My future research seeks to develop fundamental understandings of the working mechanisms and failure modes in electrochemical devices at both the macroscopic and atomic scale. Guided by these insights, I will design, synthesize, and characterize materials systems that can overcome intrinsic challenges and enable devices for practical application. Using the advanced characterization tools and chemistry expertise developed in my doctoral studies, I intend to further study the atomic structure of electrocatalysts at reaction conditions to understand their behavior during operation [5].

Selected Publications:

[1]: Y. Li, K. Yan, H.W. Lee, Z. Lu, N. Liu, Y. Cui. Nature Energy 1 (2016): 15029.

[2]: Y. Li, K. Yan, Z. Lu, Y. Cui. US Patent Application No. 15/178,366. (2016).

[3]: Yuzhang Li, Yanbin Li, Y. Sun, B. Butz, K. Yan, A.L. Koh, J. Zhao, A. Pei, Y. Cui. Nano Letters (in review)

[4]: Yuzhang Li, Yanbin Li, A. Pei, K. Yan, Y. Sun, C.L. Wu, L.M. Joubert, R. Chin, A.L. Koh, Y.Yu, J. Perrino, S. Chu, Y. Cui. Science (in review)

[5]: H. Wang, S. Xu, C. Tsai, Y. Li, C. Liu, J. Zhao, Y. Liu, H. Yuan, F. Abild-Pedersen, F.B. Prinz, J.K. Norskov, Y. Cui. Science 354.6315 (2016):1031-1036.

Teaching Interests:

My teaching audiences have spanned middle school students to post-doctoral scholars. These experiences have trained my ability to clearly explain difficult concepts in a simple or detailed manner. Coming from a chemical engineering undergraduate background, I am excited to teach a variety of courses at the undergraduate and graduate levels. In particular, I am interested in teaching materials chemistry, transport phenomena (heat, mass, momentum), and atomic structure and arrangements. Creating a great educational experience for young scientists and researchers is critical for the continued advancement of science and it is with this view that I will approach teaching as a future faculty member.

Proposal Experience:

-       Office of Energy Efficiency and Renewable Energy Materials Research Program (2016)

-       Department of Energy Batteries for Advanced Transportation Technologies (2016)