Program:
15.00-15.15: coffee & cake in the foyer
15.15-16.15: scientific talk in Auditorium I

Speaker: Joseph A Teprovich Jr., associated professor, California State University Northridge

Abstract:
Owing to the structural diversity and tunability of hydrides, they have received considerable interest for energy storage and conversion technologies such as hydrogen storage, batteries, thermal energy storage, and superconductors. More specifically, this seminar will focus on the electrochemical properties of boron-hydrogen (B_xH_y) systems and behavior of lanthanide hydride nanoparticles under extreme pressure. For example, the closo-borate anions (i.e. B₁₂H₁₂^-2, B₁₀H₁₀^-2) are considered weakly coordinating anions (WCA) due to the delocalization of the negative charge on the surface of the anion and relatively low affinity for the associated cations. As a result, they have found utilization as solid-state ion conductors for fast cation transport. While significant advancements have been made to understand the structure dynamics and function relationships of closo-borates as solid-state ion conductors, little is known about their behavior or electrochemical properties in solution or a semi-solid (gel) matrix.  To better understand the dynamics, solvation structure, and interface behavior of these systems in a common organic battery electrolyte solvent, we utilized DFT, AIMD, and optical infrared spectroelectrochemistry (OP-IR-SEC, Figure 1).¹  We also developed a Li₂B₁₂H₁₂ based gel polymer electrolyte (GPE) that enabled high ionic conductivity, operation down to -35 °, and fabrication of a flexible pouch cell battery.² Due to the high chemical stability of the closo-borate anion we have also found that they can be utilized as electrolytes for aqueous battery chemistries as well.  Recent work from our group has demonstrated that pairing the B₁₂H₁₂^-2 BWCA with a zinc cation makes it a suitable electrolyte salt for aqueous zinc ion batteries.  The resulting zinc ion batteries show good electrochemical and cycle stability.

The recent theoretical predictions and experimental confirmation of room temperature superconductivity in the superhydride, LaH₁₀, has invigorated the investigation of this class of materials.  However, in order to achieve this superconductive state, > 100 GPa of pressure must be applied which eliminates its utility for any practical application. Previous work has demonstrated that nanosizing and nanoconfinement can significantly alter the thermodynamics of hydrogen uptake and release which suggests that this approach may be utilized to lower the onset pressure of superhydride formation. A chemical approach was utilized to prepare free and nanoconfined Yb and La hydrides and their phase behavior as a function of pressure was evaluated.^3,4  The nanoscale materials showed unusual behavior as a function of pressure compared to the bulk hydride phases. This and ongoing research in both topic areas will also be discussed.

[1] ACS Appl Mater. Interfaces 2024, 16, 70028-70037   
[2] Advanced Science 2022, 9, 210632                          
[3] ACS Appl. Energy Mater. 2025, 8, 7-15
[4] ACS Appl. Energy Mater.  2024, 21, 9608-9615