Pore‐scale Modeling of Flow Batteries

Wolf, Amadeus; Kespe, Susanne; Nirschl, Hermann

doi:10.1002/9783527832767.ch18

Cited by 2 publications

(5 citation statements)

References 38 publications

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“…In general, efficient ways of passing information between different scale models are difficult to determine. This publication continues the research on multiscale modeling of flow batteries by introducing an approach for connecting a 3D-resolved MSM introduced in previous work [40] with a 2D HCSM. The work investigates flow battery performance using the MSM with reconstructed microstructure.…”

mentioning

confidence: 84%

“…In this contribution, the electrode microstructure is obtained by experimental image reconstruction. [ 40 ] In addition, an artificial structure made of cylinders is generated for comparison. Figure 1 shows the reconstructed microstructure (left) and the generated domain (right).…”

Section: Electrochemical Modelmentioning

confidence: 99%

“…Regarding the reconstructed domain, experimental images of graphite felt (SIGRACELL GFD46, SGL Carbon [ 52 ] ) are obtained via X‐ray computed micro‐tomography as described in previous work. [ 40 ] The obtained grid is a subset of the electrode sample and includes an additional current collector plate at

Z = Z^{*}

. The membrane boundary area is located at

Z = 0

(not visible).…”

Section: Electrochemical Modelmentioning

confidence: 99%

“…The MSM is validated against a homogenized and a pore‐scale vanadium model in previous work [ 40 ] due to the absence of experimental TEMPO data. In the context of this contribution, galvanostatic experiments using the TEMPO system are realized for validation.…”

Section: Experimental Validation Of the Micro‐scale Modelmentioning

confidence: 99%

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A Multiscale Flow Battery Modeling Approach Using Mass Transfer Coefficients

2023

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Driven by the transformation of the energy system and the need to store fluctuating power generation from renewable energy sources, stationary storage systems become more and more important. [1] Flow batteries are promising candidates for balancing the demand and supply in the electrical grid and thus providing continuous and reliable power supply. The unique concept of flow batteries is based on the spatial separation of electrolyte and electrode which results in the independent scalability of power and capacity. [2,3] This makes them applicable in a wide energy range of the grid infrastructure. Moreover, long operating life cycles, environmental friendliness, and nonflammability are further advantages toward predominant storage systems. [4,5] However, high capital costs and low energy density predominantly have been preventing a deep market penetration up to the present. [6] A typical flow battery consists of two independent reservoirs holding separated electrolyte solutions and two porous electrodes separated by an ion transport membrane. During operation, the electrolytes are pumped through the electrochemical cell, where the redox reaction takes place at the surface of the porous electrodes. Subsequently, the charged or discharged electrolyte flows back into the reservoir. [7,8] The all-vanadium system is so far the most studied and developed flow battery system, which convinces by the absence of material degradation and capacity fade. [9,10] However, it suffers from the comparatively high prices and enormous price fluctuations regarding the electrolyte, [11] and from the fact that vanadium is a critical raw material. [12] Recently, organic redox-active materials have emerged as a promising alternative to metal-based systems due to their low cost, structural designability, and the independence on metal mining. [13,14] For this reason, this contribution focuses on an electrolyte for aqueous organic redox flow batteries, namely 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (4-OH-TEMPO). [11,15] Simulation methods are powerful tools for gaining insight into the multiphysical processes inside the battery and for predicting its performance for various operating conditions. They provide a substantial alternative to experimental investigations as these can be very challenging and costly in terms of raw materials, physical resources, and time. Modeling approaches for flow battery components and performance apply to a wide range of length scales. This contribution focuses on a detailed microscale model (MSM) and an upscale connection to a homogenized cell-scale model (HCSM).Three-dimensional MSMs resolve the actual electrode geometry to gain insights of the micro-structural processes within the battery. The structure of the electrode is obtained by image processing and reconstructing, mostly using X-ray-computed

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mentioning

confidence: 84%

Section: Electrochemical Modelmentioning

confidence: 99%

Z = Z^{*}

. The membrane boundary area is located at

Z = 0

(not visible).…”

Section: Electrochemical Modelmentioning

confidence: 99%

Section: Experimental Validation Of the Micro‐scale Modelmentioning

confidence: 99%

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A Multiscale Flow Battery Modeling Approach Using Mass Transfer Coefficients

2023

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“…The modeled domain represents a typical, experimental flowthrough lab-scale cell, as illustrated in Figure 1. This design is chosen as it allows for experimental validation and was used in previous simulation studies [58] and experiments. [59,60] It incorporates a primary manifold at both the inlet and outlet of the electrode to ensure the uniform distribution of electrolyte.…”

Section: Computational Domainmentioning

confidence: 99%

Enhancing Flow Batteries: Topology Optimization of Electrode Porosity and Shape Optimization of Cell Design

Wolf,

Noack,

Krause

et al. 2024

Energy Tech

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This research focuses on the improvement of porosity distribution within the electrode of an all‐vanadium redox flow battery (VRFB) and on optimizing novel cell designs. A half‐cell model, coupled with topology and shape optimization framework, is introduced. The multiobjective functional in both cases aims to minimize pressure drop while maximizing reaction rate within the cell. Topology optimization results reveal dependencies on initial value, porosity constraint, and flow rate. The distribution with lower porosity is preferred downstream of the inlet manifold. This design enhances active surface area, thus facilitating more effective conversion of incoming educts and improving mass transport of products. Compared to homogeneous electrodes, two‐part design demonstrates superior performance at specific porosity values. For combined porosities of 0.7 and 0.95, optimized distribution results in 81 % reduction in pressure drop, while conversion rate decreases by 7%. As regards various cell designs, optimization suggests a need to reconsider the vertical format of a rectangular cell. Horizontal cells are favored for nearly all porosities and flow rates. Trapezoidal and radial designs characterized by reduced downstream cross sections lead to higher pressure drops and are not preferred. This work provides further valuable insight into optimizing VRFB electrodes and challenges conventional cell design assumptions.

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Pore‐scale Modeling of Flow Batteries

Cited by 2 publications

References 38 publications

A Multiscale Flow Battery Modeling Approach Using Mass Transfer Coefficients

A Multiscale Flow Battery Modeling Approach Using Mass Transfer Coefficients

Enhancing Flow Batteries: Topology Optimization of Electrode Porosity and Shape Optimization of Cell Design

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