Research Interests

Our general goal is to contribute to the fields of physical and inorganic chemistry of materials. We aim to explore boundaries of ionic conduction, redox and intercalation chemistry of solids, as well as the limits of electrochemical energy storage. Apart from sitting at the center of the wireless revolution and being touted as a critical component of a sustainable society, batteries also constitute fascinatingly complex chemical reactors. Electrochemical reactions are powerful means to explore metastable compositional spaces or the limits of redox chemistry. We aim to use our scientific advances in chemistry to find new phases or assemble known ones as complex multi-functional architectures, in which all components synergistically realize their full potential.

Our interests in inorganic chemistry lie in significantly improving our ability to synthesize compositionally and morphologically complex, stable, functional materials.  Our interests in physical chemistry focus on defining the chemical pathways of redox phase transformations in solids.  We are interested in phenomena that occur at multiple length scales, from atomic to macroscopic, or, in other words, from interfaces to particle assemblies.  As part of our quest to gain insight with increased chemical, spatial and temporal resolution, we have demonstrated a variety of analytical methodologies of chemical imaging and mapping, both in 2D and 3D.

We have active research projects in the following areas:

  • Exploration of materials suitable for electrochemical intercalation of single and multivalent ions: We aim to establish the design rules that govern ion intercalation into solid electrodes to guide the discovery of new functional materials. While this class of chemical reactions are well established for single valent ions such as Li+, they remain to be fully demonstrated in the case of multivalent ions such as Mg2+. We use  knowledge generated from characterization of known materials to inform the design of new compositions, atomic frameworks and architectures that lead to the desired properties.
  • Solid state electrochemistry of non-oxide and mixed anion compounds: Our general principle is to synergistically tailor chemical bonding and physical properties to surpass the pitfalls encountered with pure oxides.  Changes in chemical bonding provide access to and stabilize typically inaccessible formal oxidation states in transition metals, as well as tune the electrochemical potential of a redox couple.  Subsequent alteration of the band gap of the compound can result in remarkable changes in the electronic properties of the compound.
  • Colloidal synthesis of nanocrystals of high levels of chemical complexity: The explosion of nanotechnology during the past two decades uncovered the possibility of inducing non-trivial property changes in a material by preparing it in the form of nanoparticles. Using the array of strategies available from colloidal synthesis, we produce high quality particles and composites based on complex phases, preferably in dispersible form so that, through partnerships with engineers, they can be manipulated into structures where assembly is precisely controlled.
  • Definition of chemical pathways of redox phase transformations in solids, at scales spanning from atoms to micrometers, and from bulk to interfaces: Phase transformations during electrochemical reactions can induce severe mechanical damage to particles, which compromises the ability to cycle between end phases.  Secondary reactions can lead to byproducts that impede the desired primary processes altogether. We apply a suite of existing characterization tools to define processes in the bulk and at interfaces. We are particularly biased toward X-ray methods, in the lab and in synchrotron user facilities, because of the rich structural and chemical information they offer. Our recent results using chemical imaging are summarized in this 2017 talk: