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Free, publicly-accessible full text available June 8, 2024
Despite extensive research efforts in developing aqueous rechargeable zinc metal batteries (RZMBs) as high-energy-density alternatives to both lithium ion and lithium metal batteries, the commercial prospects for RZMBs are still obfuscated by fundamental scientific questions. In particular, the electrode–electrolyte interphase properties and behaviors are still intensely debated topics in this field. In this review, we provide a comprehensive and thorough overview of the solid electrolyte interphase (SEI) and cathode electrolyte interphase (CEI) in aqueous RZMBs, with an emphasis on the formation mechanisms and characteristics of the SEI and CEI. We then summarize state-of-the-art techniques for characterizing the SEI/CEI to reveal the intrinsic correlation between the functionalities of the interphases and the electrochemical performances. Finally, future directions are proposed, including studies on aqueous SEI/CEI evolution as a function of pH and temperature, as well as SEI/CEI studies for high-energy-density and long-lifetime RZMBs.more » « lessFree, publicly-accessible full text available March 14, 2024
In this paper, we present an approach to obtain a desired leading-edge vortex (LEV) shedding pattern from unsteady airfoils through the execution of suitable motion kinematics. Previous research revealed that LEV shedding is associated with the leading-edge suction parameter (LESP) exceeding a maximum threshold. A low-order method called LESP-modulated discrete vortex method (LDVM) was also developed to predict the onset and termination of LEV shedding from an airfoil undergoing prescribed motion kinematics. In the current work, we present an inverse-aerodynamic formulation based on the LDVM to generate the appropriate motion kinematics to achieve a prescribed LESP variation, and thus, the desired LEV shedding characteristics from the airfoil. The algorithm identifies the kinematic state of the airfoil required to attain the target LESP value through an iterative procedure performed inside the LDVM simulation at each time step. Several case studies are presented to demonstrate design scenarios such as tailoring the duration and intensity of LEV shedding, inducing LEV shedding from the chosen surface of the airfoil, promoting or suppressing LEV shedding during an unsteady motion on demand, and achieving similar LEV shedding patterns using different maneuvers. The kinematic profiles generated by the low-order formulation are also simulated using a high-fidelity unsteady Reynolds-averaged Navier–Stokes method to confirm the accuracy of the low-order model.more » « less
This paper presents a state-variable formulation to model and simulate the 2D unsteady aerodynamics of an airfoil undergoing arbitrary motion kinematics. The model builds upon a large-angle unsteady aerodynamic formulation in which the airfoil is represented using a lumped vortex element (LVE) model. The airfoil is divided into several panels, with a bound vortex placed on each panel. At any time instant, the bound-vortex strengths are determined by employing zero-normal-flow conditions at the control points located on each panel. The vorticity shed from the trailing edge of the airfoil is modeled using discrete vortices that move freely in the flow field. The required state variables are first identified, and all the time derivative terms of the state variables are then derived to form the final state-variable representation. Trailing-edge vortex shedding is incorporated using the Kelvin condition. The final state variable equation can be solved as an ordinary differential equation using any standard ODE-solving algorithm. Three case studies are presented here to evaluate the predictions of the model. In the cases considered here, the airfoil undergoes various unsteady plunge motions. The aerodynamic load history and the wake patterns are compared against the results from the low-order model developed by Narsipur et al.  in previous research. The comparison shows that the current state-variable formulation captures the unsteady flow characteristics and the aerodynamic load in good agreement with the reference results.more » « less