(7gf) 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)