Committee Members:     

Prof. Gleb Yushin, Advisor, MSE  

Prof. Preet Singh, MSE  

Prof. Seung Soon Jang, MSE  

Prof. Faisal Alamgir, MSE  

Prof. Alexander Alexeev, CHEM  

Borohydride-based Solid Electrolytes and Polymer Composite Separators for Lithium and Lithium-Ion Batteries

Abstract:

 Borohydride based solid electrolytes are gaining increasing interest as solid electrolytes due to their high ionic conductivity, facile synthesis, and low melting points. However, their electrochemical performance and mechanical properties haven’t been well studied. In my thesis work, I would like to study the electrochemical properties of doped and nano-confined versions of borohydride-based electrolytes and test these solid-electrolytes in all solid-state Li and Li-ion batteries using both intercalation and conversion type electrodes. The composition and microstructures of these electrolytes will be explored using X-ray diffraction (XRD), Energy Dispersive Spectroscopy (EDS) and scanning electron microscope (SEM). All-solid-state batteries will be fabricated with commercial and in-house made cathode and anode materials. Interactions of the electrolytes with the electrodes, the composition of the solid electrolyte interphase (SEI) and key failure mechanisms layers will be carefully investigated.

The addition of nano-fillers into electrolytes and separator membranes is another promising approach to improve Li and Li-ion battery cell performance. Nanodiamonds (NDs) are a relatively unexplored class of carbon nanoparticles featuring high surface-to-volume ratio, tunable size and surface functionalization, high elasticity moduli, and exceptional thermal conductivity. Although NDs exhibit properties that may be beneficial to Li-ion batteries separators, their use as nano-fillers in battery polymer separators is still unexplored. In my work, I would also like to explore the effect of NDs as fillers in polymer separators fabricated through electrospinning. The composition and microstructure of the polymer composites will be studied using XRD and fourier transform infrared spectroscopy (FTIR) and SEM and transmission electron microscopy (TEM), respectively. Cell rate performance and stability as well as Li dendrite suppression abilities of the separators with and without ND fillers will be systematically studied.