We are interested in synthesizing nanostructured materials and probing the effect of composition and size on the thermodynamics and kinetics when they are used as battery materials.

Nanoscale materials exhibit fast reaction rates due to high surface areas and short diffusion lengths that can significantly improve the power density of electrochemical devices such as rechargeable batteries.  Theoretically, these nanomaterials are also expected to display effects beyond improved kinetics, including: 1) enhanced electrode cycle life due to improved mechanical properties; and 2) modified phase diagram behavior due to enhanced solid solution formation over phase separation. We are interested in understanding the effect of nanostructuring on complex battery reactions involving multiple solid state phases that underpin promising high energy-density battery chemistries.  Previously, we have examined the reaction mechanism of Li/FeF3 – how the nanocomposite of LiF/Fe can reform iron fluoride upon lithium removal including the source of large hysteresis and rate limiting steps during structural transformation as well as the instability of the LiF/Fe nanocomposite. We are leveraging these mechanistic understandings to develop methods to improve reaction reversibility through manipulating reaction pathways and nanostructure design.

Hysteresis

 

Reaction Mechanism
 Understanding the reaction mechanisms of nanocomposite materials during battery operation can help us develop materials solutions to overcome the large hysteresis.

Reference: Thermodynamics and kinetics of the Li/FeF3 reaction by electrochemical analysis, P. Liu, J. Wang, W. Li, J. Liu, and J. Vajo, The Journal of Physical Chemistry C, (2012), 116 (10), 6467-6473.