Associate Professor Joseph Teprovich, Department of Chemistry & Biochemistry, California State University Northridge

Hydrogen rich clusters and nanomaterials for energy applications

Owing to the structural diversity and tunability of hydrides, they have received considerable interest for energy storage and conversion technologies including, but not limited to hydrogen storage, batteries, thermal energy storage, and superconductors. This lecture will discuss prior and ongoing research in our lab with a focus on closo-borate electrolytes and lanthanide hydride nanomaterials.  While significant advancements have been made to understand the structure-dynamics and function relationships of closo-borate electrolytes in the solid-state, little is known about their behavior or electrochemical properties in solution or a semi-solid (gel) matrix.  By investigating the design space in this relatively unexplored area, it may be possible to overcome two of the research needs for the realization of closo-borate electrolytes in practical battery systems:  1.) reduce the thickness of the electrolyte layer, 2.) operation at and below ambient temperature.  We 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 (Figure 1a).  We are also utilizing a FTIR microscope to simultaneously monitor chemical species at the electrode-electrolyte interface and image dendrite formation with closo-borate electrolytes. Additionally, pairing the B₁₂H₁₂^-2 atomic cluster with a zinc cation makes it a suitable electrolyte salt for aqueous zinc ion batteries. 

 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, > 200 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 developed and utilized to prepare free (Figure 1b) and nanoconfined (Figure 1c) Yb and La hydrides.  Diamond anvil testing of the YbH_x nanoparticles showed a unique behavior of the Pmna phase up to 60 GPa.  This and ongoing research in this area will also be discussed.

See References:  Advanced Science, 2022, 9, 210632; Applied Science, 2022, 12, 2273

* Closo-borate electrolyte research is funded by the National Science Foundation (NSF) LEAPS-MPS Program – Award # 2137973 ** Lanthanide hydride nanomaterial research is funded by the Sandia National Laboratories LDRD program