Current Research
We utilize colloidal wet synthetic syntheses to design inorganic nanocrystals in unconventional crystal phases, compositions and morphologies. We are developing the fundamental understanding of the mechanistic pathways responsible for the progressions in these in exchange transformations at the nanoscale. Structural configurations, electrochemical performance and mechanical stabilities found in these nanocrystals are promising for solid inorganic electrolyte design and future deployment in Li & Na-ion batteries to improve safety and enhance sustainability in the battery supply chain.
Thrust IA. Development of new battery chemistries utilizing sustainable elements
IB. Battery fabrication and testing
Thrust II. Integrate automation into synthesis & testing
Thrust III. Chemical recycling of spent solid batteries to counteract supply chain challenges
Past Research Projects of the PI
A. Tailoring of the ionic occupancies, compositions and realization of the exchange of ionic species in inorganic nanocrystals using wet chemistry for understanding the superionic mobilities for solid electrolyte applications
Superionic conductivity was realized in Progna’s doctoral dissertation with several orders of degrees of higher ionic conductivities in inorganic chalcogenide nanocrystals synthesized with ionic replacement from quantum dots and crystals. The cationic sublattice “melts” above a phase transition temperature (283 K in our nanoclusters, as compared to 414 K in the bulk material) driving the free movement of cations in the lattice. The atomic scale wet colloidal ionic replacement technique called “cation exchange” was utilized to demonstrate the unique defect-driven structural fingerprint associated with superionic conductors. This work was extended to incorporate lithium ions in these nanocrystals for the first time under ambient conditions with a reaction time of minutes, compared to conventional methods which require ~1000 oC reaction conditions over days.
Research Highlight: Featured on several science and general news outlets including Smithsonian magazine, R&D Magazine, AzoNanao, CEMag, Phys.Org, EurekAlert, UIUC News Bureau etc. Read the excerpt from Smithsonian placing our studies in perspective with the emerging technologies in solid state battery technology here.
References: Banerjee (co-first) et. al., Nature Communications, 8, 14514, 2017, Banerjee et. al., Angewandte Chemie Int. Ed., 57 (30), 9315-9319, 2018
B. Extension of the feasibility of ionic replacement in two-dimensions in ultra-thin atomically precise nanoplatelets of inorganic chalcogenides
Extension of this structure-property correlation to 2D nanoplatelets and additional Cu-sources were performed during Progna’s postdoctoral research at Argonne National Laboratory. These studies enabled both the synthetic yields of copper chalcogenides with unconventional vacancy occupations, morphologies, series of unique compositions, and dimensionalities; while simultaneously pushing the understanding of cation exchange pathways in relation to relatively unexplored reaction parameters (guest ion valency, atmospheric oxygen, redox states).
Reference: Banerjee et. al., Chemistry of Materials, 35, 21, 8872-8882, 2023
C. Demonstration of mechanical stability of these superionic nanocrystals up to Gigapascals of high pressure (extreme environments)
Using the atomic level tailoring method called “cation exchange”, faceted nanocrystals and 2D nanoplatelets of inorganic chalcogenides were synthesized through wet colloidal techniques. Next, the GSECARS high pressure beamline at Advanced Photon Source was utilized to apply high pressure on these materials using a diamond anvil cell, while obtaining x-ray diffraction patterns at various pressures in the GPa range. A phase transition was observed from the zinc blende to a CsCl-type structure above 4 GPa. These results are important for the design of energy materials for high stability under extreme environments.
Reference: Banerjee et. al., Nano Letters, 24, 23, 6981–6989, 2024
D. Demonstration of mechanical stability under extreme environments in MXenes
Pressure-dependent structural studies were undertaken using 2D MXene Ti3C2Tx systems with various chemical attachments (T = Cl, Br etc.) to understand their crystalline stability and pressure-mediated defect arrangements. The goal is to try to decipher the various crystalline MXene arrangements conducive to percolative Li+ pathways, and to eliminate the fast combination between Li+ and e–. The latter is the leading cause towards uneven Li deposition and problematic dendrites and dead phases in solid electrolytes. A suitable chemical termination prevents the MXene structure from significant distortion, suggesting an important role in the deployment of these materials in energy storage applications under extreme environments.
E. High-throughput inorganic syntheses using liquid-handling platforms
One of the techniques for high throughput synthesis of colloidal nanomaterials is through the use of an autonomous liquid handling robotic platform, which can provide rapid mapping of various parameters in the desired synthesis space.
Material discovery is an arduous process which requires years worth of hard work and thousands of experiments to barely scratch the parameter space for a chosen combination of materials and operating conditions. Using nanoscale transformations and microfluidic technologies, we are striving to create a self-operating lab platform starting with colloidal sample handling, mixing, reactors, followed by in-built characterization tools for quality assessment and measurements of crucial physicochemical properties.
F. Chirality transfer in hybrid halide perovskite nanoplatelets
Halide perovskite 2D nanoplatelets show step-wise chirality transfer from organic ligands, with various stages of self-assembly visualized using HR-TEM imaging. Chiral metal-halide perovskites are promising candidates to control spin, charge, and light for applications in solar cells, spin-LEDs, chiral optoelectronics, ferroelectrics, spintronics.
A fundamental aspect of this research was establishing a correlation between the structural characteristics of the perovskite nanoplatelets, the properties of the organic chiral ligands, and the resulting chiral light-matter interactions. By analyzing diffraction patterns and spectroscopic data, a comprehensive understanding of how nanoplatelet size, composition, and ligand structure influenced the observed optical responses was developed. Manuscript containing various findings from these multiple studies is under preparation.
G. Bioinspired materials studied for their anti-reflective properties
Insects produce/secrete fascinating biomaterials- which are only starting to be investigated mechanistically through innovative biomimetic manufacturing processes to find suitable applications in defense. As part of the ARO-funded MURI team, I studied brochosomes, which are spheroidal nanostructures produced by leafhopper insects that exhibit superhydrophobicity, antireflectivity, and other properties.
My research on investigating the mechanistic insights of light-matter interaction in leafhopper brochosomes using a finite element method computation technique- coupled with optical experiments, attributes the ultra-high antireflective behavior in these nanoscale biomaterials to a Fano resonance induced coupling.
Reference: Banerjee et. al., Advanced Photonics Research, 4, 7, 2200343, 2023
H. Dissemination of plasmonic modes using monochromated EELS
Electron energy loss spectroscopy (EELS) is a nanoscale hyperspectral technique used to understand the optical response and compositional attributes in nanocrystal assemblies. There has been a recent push for new experimental methodologies that can provide comprehensive information about a complex system at the nanoscale, while concurrently being time efficient and resulting in high fidelity data. I collaborated with the Oak Ridge National Laboratory‘s CNMS team on disseminating the plasmonic modes resulting from the surface, bulk, edge etc. of a single plasmonic oxide nanoparticle.
Reference: Journal of Chemical Physics, 154, 014202, 2021.
I. Plasmonic near-field interactions as visualized using spectroscopy, microscopy and optical simulations
Scanning tunneling spectroscopy is a technique applied recently at the single particle level to visualize the near-field distribution in plasmonic nanoparticles. Single particle STS applied to Au nanoislands can effectively map the charge density around the proximity and hence provide a quantitative estimate of the strength of the near-field interaction. Using computational techniques qualitative proofs were provided in such studies through proposing correlations between the experimentally obtained charge maps with simulated near-field intensity distributions.
Reference: Banerjee et. al., Journal of Physical Chemistry Letters, 9 (8), 1970-1976, 2018.
Banerjee Battery Research 