Shirley Meng, "Advanced Diagnostic Tools for Lithium Metal and Solid State Batteries"
Lithium (Li) metal has been considered as an ideal anode for high-energy rechargeable Li batteries while Li nucleation and growth at the nano scale remains mysterious as to achieving reversible stripping and deposition. A few decades of research have been dedicated to this topic and we have seen breakthroughs in novel electrolytes in the last few years, where the efficiency of lithium deposition is exceeding 99%. Here, cryogenic-transmission electron microscopy (Cryo-TEM/Cryo-FIB) was used to reveal the evolving nanostructure of Li deposits at various transient states in the nucleation and growth process, in which a disorder-order phase transition was observed as a function of current density and deposition time. More importantly, the complementary techniques such as titration gas chromatography (TGC) reveals the important insights about the phase fraction of solid electrolyte interphases (SEI) and electrochemical deposited Li (EDLi). While cryo-EM has made significant contributions to enabling lithium metal anodes for batteries, its applications in the area of solid state electrolytes, thick sulfur cathodes are still in its infancy, therefore, I will discuss a few new perspectives about how future cryogenic imaging and spectroscopic techniques can accelerate the innovation of novel energy storage materials and architectures.
Jue Liu, "Recent development of operando neutron diffraction for studying energy storage materials"
Neutron scattering has unique advantages for battery research. It is very sensitive to light elements (e.g., H, Li, C, and O), which are the most important ingredients for rechargeable Li/Na-ion batteries. It can also distinguish adjacent transition metal (TM) cations (e.g., Mn, Fe, and Ni) in battery cathodes, especially when conducting isotope substitution experiments. This capability allows accurate investigation of how cation arrangements affect the electrochemistry performance of various rechargeable battery cathodes. Neutron scattering can also be used to probe dynamics, particularly ligand anion vibration/lattice dynamic and ionic diffusions, in both electrode and electrolyte materials. Moreover, the strong penetration and nondestructive nature of neutron scattering makes it an ideal tool to characterize battery materials without damaging the sample or disturbing the electrochemical reactions. Despite all these advantages, the use of neutron scattering (e.g., diffraction, quasi-elastic and inelastic scattering) for battery research has often been confined to ex situ studies of pristine or postmortem samples recovered from charged/discharged batteries. Although they may provide useful information about the functionality of individual components (e.g., cathode or anode), they often fail to provide key insights about what governs the battery performance. Furthermore, many charged or cycled materials are metastable, and recovered ex situ samples often differ from those under real operational conditions. Thus, developing operando neutron scattering capability, with the needed spatial/temporal resolution, is highly desired to fully unleash the unique advantages of neutron scattering for battery research. In this talk, I will present our recent efforts on developing neutron scattering friendly in situ electrochemical cells, sample environments and related data reduction and analysis routines. Particularly, I will present the first high throughput and fast operando neutron diffraction study of the conventional Li-ion batteries, and the recent breakthrough of realizing the first operando neutron diffraction study of all solid-state batteries at NOMAD.
Kimberly See, "Controlling Anion Redox in Li-Rich Chalcogenides"
The capacity of conventional intercalation cathode materials in Li-ion batteries is limited to less than one electron per transition metal. We aim to go beyond this limitation to achieve higher capacity materials using abundant transition metals. Employing the redox activity of anions increases the charge storage capacity significantly, however, control over access to anionic electronic states and reversibility is limited. We study the mechanisms of anion redox in sulfides and selenides with Earth abundant transition metals to develop design rules for achieving reversible, high capacity cathodes. Sulfides yield much more reversible anion redox compared to oxides thanks to the stability of oxidized S species, like persulfides. We will discuss the effects of anion substitution, alkali metal substitution, transition metal substitution, and cationic vacancies on the anion redox in phases like Li2FeS2 and Li2TiS3.
David Kwabi, "Understanding Chemical and Electrochemical Processes in Organic Redox-Flow Batteries”
Avoiding the most severe consequences of climate change will require drastic reductions in net anthropogenic CO2 emissions. These reductions can be achieved by increasing the pace at which carbon-free/renewable power is adopted in place of fossil fuel-based power. Because renewable (e.g., solar and wind) power is intermittently available, cost-effective means of storing it are critically needed so that it can be extensively used on the electric grid. Organic redox-flow batteries are widely seen as a promising technology for this purpose. However, they face barriers to widespread deployment owing to the vulnerability of their charge-storing materials to decomposition. In this talk, I will introduce our group’s recent progress in using numerical modeling and statistical inference techniques to understand how chemical and electrochemical processes in organic redox-flow batteries compose their observed performance. I will specifically discuss how we have applied Bayesian and multivariate curve regression techniques to spectroscopic data from operating batteries to characterize operative decomposition mechanisms. This work has the potential to direct rapid design of new, durable chemistries for next-generation organic flow batteries.
