Garrett P. Wheeler

Bio: Garrett P. Wheeler is an academic researcher from Stony Brook University. The author has contributed to research in topics: X-ray absorption spectroscopy & Hysteresis. The author has an hindex of 2, co-authored 4 publications receiving 24 citations. Previous affiliations of Garrett P. Wheeler include Brookhaven National Laboratory.

Regulating electrodeposition morphology in high-capacity aluminium and zinc battery anodes using interfacial metal–substrate bonding

Abstract: Although Li-based batteries have established a dominant role in the current energy-storage landscape, post-Li chemistries (for example, Al or Zn) are emerging as promising candidates for next-generation rechargeable batteries Electrochemical cells using Al or Zn metal as the negative electrode are of interest for their potential low cost, intrinsic safety and sustainability Presently, such cells are considered impractical because the reversibility of the metal anode is poor and the amount of charge stored is miniscule Here we report that electrodes designed to promote strong oxygen-mediated chemical bonding between Al deposits and the substrate enable a fine control of deposition morphology and provide exceptional reversibility (996–998%) The reversibility is sustained over unusually long cycling times (>3,600 hours) and at areal capacities up to two orders of magnitude higher than previously reported values We show that these traits result from the elimination of fragile electron transport pathways, and the non-planar deposition of Al via specific metal–substrate chemical bonding Using metal anodes could in principle boost the energy density of batteries but their electrodeposition often negatively impacts battery performance Here the authors propose an oxygen-mediated metal–substrate bonding strategy to regulate metal deposition and demonstrate highly reversible Al and Zn anodes

Nickel-rich Nickel Manganese Cobalt (NMC622) Cathode Lithiation Mechanism and Extended Cycling Effects Using Operando X-ray Absorption Spectroscopy

Abstract: Ni-rich NMC materials are a particularly promising class of Li-ion cathodes for various applications. LiNi0.6Mn0.2Co0.2O2 (NMC622) offers a unique balance of thermal stability and energy density, t...

Impact of Charge Voltage on Factors Influencing Capacity Fade in Layered NMC622: Multimodal X-ray and Electrochemical Characterization.

Abstract: Ni-rich NMC is an attractive Li-ion battery cathode due to its combination of energy density, thermal stability, and reversibility. While higher delivered energy density can be achieved with a more positive charge voltage limit, this approach compromises sustained reversibility. Improved understanding of the local and bulk structural transformations as a function of charge voltage, and their associated impacts on capacity fade are critically needed. Through simultaneous operando synchrotron X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) of cells cycled at 3-4.3 or 3-4.7 V, this study presents an in-depth investigation into the effects of voltage window on local coordination, bulk structure, and oxidation state. These measurements are complemented by ex situ X-ray fluorescence (XRF) mapping and scanning electrochemical microscopy mapping (SECM) of the negative electrode, X-ray photoelectron spectroscopy (XPS) of the positive electrode, and cell level electrochemical impedance spectroscopy (EIS). Initially, cycling between 3 and 4.7 V leads to greater delivered capacity due to greater lithium extraction, accompanied by increased structural distortion, moderately higher Ni oxidation, and substantially higher Co oxidation. Continued cycling at this high voltage results in suppressed Ni and Co redox, greater structural distortion, increased levels of transition metal dissolution, higher cell impedance, and 3× greater capacity fade.

Regulation methods for the Zn/electrolyte interphase and the effectiveness evaluation in aqueous Zn-ion batteries

Abstract: Aqueous Zn-ion batteries (ZIBs) have inspired an overwhelming number of literature studies due to their safety, cost effectiveness, and environmental benignity. Directly employing metallic Zn foil as an anode significantly simplifies battery manufacturing and simultaneously broadens the operating voltage window of aqueous batteries, benefiting from its high overpotential against electrolyte decomposition. Nevertheless, serious issues, such as dendrite growth and side reactions, occurring at the Zn/electrolyte interphase, make the Coulombic efficiency and lifespan of Zn metal electrodes far from satisfactory, which has also been motivating new research interest in interfacial engineering to solve these problems. Owing to the rapid evolution of this new area, it is highly desirable to provide current and timely updates of interfacial strategies and their effectiveness evaluation. From the two sides – the electrode and the electrolyte at the interphase – this review thoroughly summarizes our fundamental understanding of interfacial strategies, including designing mechanisms, creating new methods, and technical challenges. Importantly, this review also analyses the effectiveness evaluation techniques for interfacial strategies, including electrochemical methods, characterization measurements, and computational simulations, providing guidelines for the accurate evaluation and analysis of ZIBs in the future.

Insight on Organic Molecules in Aqueous Zn‐Ion Batteries with an Emphasis on the Zn Anode Regulation

Abstract: Rechargeable aqueous zinc ion batteries (AZIBs), as a rising star in aqueous ion batteries, are restricted by the narrow voltage window and the unsatisfactory reversibility, which are dominated by the high activity of H2O molecules, side reaction, Zn dendrites, and structural degeneration of the cathode. Electrolyte manipulation has seen a great deal of research recently, particularly various kinds of organic molecules have been shown to achieve outstanding effects on stabilizing the Zn anode, yet the exploration of the mechanism behind the high performance has not been thorough. In an attempt to find such underlying principles, the basic reactions and the corresponding progress on the anode side of AZIBs are first assessed. Then, the roles of organic molecules in recent studies are researched, followed by a deep insight into the role of organic molecules. Finally, several designed strategies are proposed for the further exploration of high performance aqueous rechargeable ZIBs through incorporating appropriate organic molecules in the electrolytes.

Understanding the Degradation Mechanism of Lithium Nickel Oxide Cathode for Li-Ion Batteries

Abstract: The phase transition, charge compensation, and local chemical environment of Ni in LiNiO2 were investigated to understand the degradation mechanism. The electrode was subjected to a variety of bulk and surface-sensitive characterization techniques under different charge-discharge cycling conditions. We observed the phase transition from the original hexagonal H1 phase to another two hexagonal phases (H2 and H3) upon Li deintercalation. Moreover, the gradual loss of H3-phase features was revealed during the repeated charges. The reduction in Ni redox activity occurred at both the charge and the discharge states, and it appeared both in the bulk and at the surface over the extended cycles. The degradation of crystal structure significantly contributes to the reduction of Ni redox activity, which in turn causes the cycling performance decay of LiNiO2.