Zn-driven Power Shift: Expanding the Search for Next-Gen Batteries
The integration between economic development and environmental impact, which is one of the great challenges of the 21st century, poses the need for the development of novel sustainable energy sources and energy storage systems.
Multivalent metal-ion batteries (e.g., Ca2+, Mg2+, Al3+) have been explored as an alternative battery technology to monovalent lithium-ion batteries (LIB), as their charges allow for high volumetric energy densities. Zinc-ion batteries (ZIB), in particular, have recently gained attention due to their environmental sustainability, compatibility with aqueous electrolytes, low toxicity, and high reversibility.
However, the high volumetric capacity associated with Zn can result in higher electrostatic interactions, which in turn give rise to slower
diffusion rates, structural degradation of the electrode materials over repeated cycles, and/or formation of inactive layers on their surface.
Within this background, we have evaluated the performance of candidate battery materials through an investigation of the main energy transfer mechanism occurring in zinc-ion batteries (i.e. Zn intercalation, phase transformations, dissolution, or deposition of species on the electrodes). In this work, we employ the pre-existent automated computational infrastructures developed by our group to search for high-performance multivalent cathodes for zinc-ion batteries. We have employed a screening funnel to identify the most promising intercalation hosts based on a set of criteria, and we utilized high-throughput DFT calculations to study the behavior of Zn2+ in intercalation processes. We then investigated Zn diffusivity in the most promising Zn candidate cathodes.
Dr. Roberta Pascazio is currently a Postdoctoral fellow in the Department of Materials Science and Engineering at the University of California, Berkeley, and at the Lawrence Berkeley National Laboratory under the supervision of Professor Kristin Persson. She received her Ph.D. in Nanochemistry in 2024 from the University of Genova/Italian Institute of Technology (IIT), in Italy, where she investigated the atomistic description of quantum dots through computational methodologies. Dr. Pascazio has taken on the challenge of discovering innovative materials for cathodes in multivalent batteries through high-throughput calculations and atomistic simulations of large databases of potential candidates.
Massive Exciton Binding Energy Renormalization and Dissociative Linewidths in BiVO4 via Phonon Scattering
The role of phonon scattering in the optical properties of materials has been a topic of growing interest, with prior first-principles calculations showing phonon exchange between electrons and holes can both renormalize exciton binding energies and result in the dissociation of bound electron-hole pairs [1-2]. In this talk, I showcase the results of including these interactions at various temperatures in the monoclinic phase of BiVO4, an indirect gap semiconductor with promising photocatalytic properties. At T=0 K, I will show that the binding energy of the first exciton is nearly halved and that this state has a finite lifetime on the order of single picoseconds due to spontaneous phonon emission. At room temperature, I will show that the first exciton peak is renormalized so dramatically that it lies above the electronic gap and that the lifetime of this state is on the order of single femtoseconds. Incorporating these effects into the optical absorption spectra, I find greatly improved agreement with the experiment. These results highlight the potential importance of including phonon screening in the calculation of optical properties of materials, and thus I conclude by discussing general criteria for when phonon screening will play an important role in the calculation of optical properties.
Stephen Gant is a 6th year Physics PhD Student working in Professor Jeff Neaton's Group. Gant's research uses density functional and many-body perturbation theory methods to calculate the excited state properties of real materials from first principles. More specifically, Gant's current focus is investigating the effects of including lattice vibrations (aka phonons) on the optical properties of materials.
[1]A. M. Alvertis, et al., PNAS 121, e2403434121 (2024).
[2] C. J. N. Coveney, et al., Phys. Rev. B 110, 054307 (2024).