Model-based simultaneous optimization of multiple design parameters for lithium-ion batteries for maximization of energy density

De, Suvranu; Northrop, Paul W. C.; Ramadesigan, Venkatasailanathan; Subramanian, Venkat R.

doi:10.1016/j.jpowsour.2012.11.035

Cited by 81 publications

(55 citation statements)

References 29 publications

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“…While in the past we have used P2D model for design purposes 10 and have published on efficient simulation of P2D models, 11 in this paper, we revisited the simple resistance model for battery electrodes keeping the independent variables to just 1D (x in this case). Use of P2D models means including at least one more independent variable (t) and possibly the independent variable for the radial direction (r).…”

Section: Choice Of the Model: Resistance Model For Battery Electrodesmentioning

confidence: 99%

Is There a Benefit in Employing Graded Electrodes for Lithium-Ion Batteries?

Jang

Ramadesigan

et al. 2017

J. Electrochem. Soc.

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Literature reports show both benefits and negligible impact when including graded electrodes in battery design, depending upon the exact model and conditions used. In this paper, we use two different optimization approaches for a secondary current distribution porous electrode model with nonlinear kinetics to confirm that computed solutions are correct. We use these confirmed optimal solutions to probe several ways that graded porosity can improve electrode performance. Single objective optimization such as reducing the overall electrode resistance using a graded electrode design provides a modest 4-6% reduction in resistance for typical lithium-ion battery parameters. Multiple objective optimization-for example, simultaneously considering electrode resistance and the overpotential variance and eventually the overpotential average as well-shows that multilayer designs open up a much richer feasible design space for achieving multiple goals. The ultimate answer to the value of graded electrodes will be the techno-economic analysis that links the benefits of an expanded optimal design space to the detrimental costs associated with manufacturing multilayer electrodes. An open-access executable code that can give optimal porosity distribution of any specified chemistry and detailed explanation of the two approaches can be found on the Subramanian group's website. Modeling and mathematical optimization can significantly improve the efficiency of battery design, helping to meet the growing demands for various applications. The idea of using modeling for battery design was first introduced by Tiedemann and Newman in 1975. 1 They used an ohmically limited porous electrode model to maximize the cell's effective capacity by changing the electrode thickness and porosity. Newman later applied the reaction-zone model to maximize the specific energy of the system, taking mass into consideration as well.2 For these two models, the objective function can be directly related to the design variables, thus the optimum can be obtained by simply observing the plot or from the analytical solution. They further optimized the thickness and porosity of a lithium iron phosphate 3 electrode, where they maximized the specific energy using the Ragone plots. Ramadesigan et al.4 went one step further by including the linear electrode kinetics to minimize the internal resistance of the electrode. They used control vector parameterization (CVP) to minimize the ohmic resistance in the positive electrode by varying porosity.With the development of battery modeling, more physical processes have been included, and one of the most popular physics based models is the pseudo-2-Dimensional (P2D) model developed by the Newman group. 5 The P2D model involves a set of nonlinear partial differential equations (PDEs) that can only be solved numerically. Therefore, a numerical optimization approach is required to perform optimization on the system. Du et al. proposed a surrogate-modelbased approach, 6 and later developed a sophisticated framework based on th...

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Section: Choice Of the Model: Resistance Model For Battery Electrodesmentioning

confidence: 99%

Is There a Benefit in Employing Graded Electrodes for Lithium-Ion Batteries?

Jang

Ramadesigan

et al. 2017

J. Electrochem. Soc.

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Diffusion‐Limited C‐Rate: A Fundamental Principle Quantifying the Intrinsic Limits of Li‐Ion Batteries

Heubner

Schneider

Michaelis

2019

Advanced Energy Materials

111

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carried out to improve the energy density at the cell level, such as the development of high capacity anode [8,9] and cathode [10,11] materials, improvements of the electrode design [12,13] and composition [14][15][16] as well as optimization of the cell architecture. [17,18] Moreover, researchers analyzed the rate limiting factors of electrodes for LIBs in great detail to understand the complex charge transport and transfer reaction processes and optimize materials and cell components accordingly. [19] It has been found that the rate performance can be improved by increasing solid-state diffusivity, [20] conductive additive type and content [21] or electrode porosity, [22] by the optimization of electrolyte properties, such as concentration [23] and viscosity, [24] and by decreasing the particle size of active materials [13,25] and the electrode thickness. [26][27][28] Although these measures lead to a gradual improvement of decisive performance metrics, a tradeoff between energy and power density became obvious, forbidding arbitrary combinations of high storage capacity and fast charging capability. Understanding this tradeoff and the accompanied practical limits of LIBs is critical for their further improvement and the development of "beyond Li" battery technologies.Herein, we present a simple but powerful electrochemical principle describing the tradeoff between storage capacity and rate capability of electrodes for LIBs. Such electrodes are porous composites consisting of particles of the active storage material, binder and conductive additives coated on a metallic current collector foil. The pores are filled with a liquid electrolyte containing Li-ions as charge carriers. The specific capacity (energy density equivalent) of such an electrode is given by the specific capacity of the active material and its share in the electrode. Figure 1 illustrates the sensitivity of the specific capacity to the most decisive electrode parameters using a typical LiNi 1/3 Mn 1/3 Co 1/3 O 2 (NCM111)-based cathode as the baseline (see Section S3 in the Supporting Information for details on the computations). Please note that here the specific capacity of the electrode also includes the masses of conductive additives, binder, current collector and the pore electrolyte, which is often ignored in the literature but has significant impact on the energy density (see Section S2 in the Supporting Information for details). It turns out that some electrode properties hardly affect the energy density, such as the porosity, the conductive additive and binder content, and the particle size (cf. Figure 1).The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/aenm.201902523.Li-ion batteries (LIBs) were continuously improved over the last decades, aiming at longer operating times of mobile electronic devices and mass implementation in high-energy applications, such as all-electric or hybrid-electric vehicles. [1][2][3][4] However, owing to safety concerns, range limitations, and inad...

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“…8,12 In addition to approaches where the optimization is performed manually, optimization algorithms have been coupled with cell physics-based models to optimize over multiple parameters, a more effective approach than manually varying individual parameters. [13][14][15][16] However, it is not clear that these approaches have resulted in any changes in design in commercial batteries, mostly due to the lack of manufacturing methods to fabricate thick electrodes that exhibit the lifetimes needed for most applications.Recently, new electrode fabrication methods have been proposed that attempt to circumvent the manufacturing challenges with using traditional slot die casting to fabricate thick electrodes. [17][18][19] These approaches have proposed to go beyond the basic approach of optimizing the porosity and thickness by focusing on varying the porosity.…”

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confidence: 99%

On Graded Electrode Porosity as a Design Tool for Improving the Energy Density of Batteries

Dai

Srinivasan

2015

J. Electrochem. Soc.

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As the need for higher energy density batteries increases, there have been numerous attempts at tuning the design of the battery electrodes to improve performance. Increasing the electrode loading remains a straightforward method to increase the energy density. Li-ion batteries are typically liquid phase limited; therefore, battery designers attempt to increase the electrode thickness and decrease the porosity until polarization losses become significant. It is in this context that a graded porosity, with varying porosity across electrode, has been explored to reduce liquid phase limitations and thereby decrease the polarization losses. In the literature, mathematical models have been used to suggest that varying porosity designs can lead to improved energy density. In this paper we show that such an enhanced improvement is an artifact of the previous models using arbitrary base cases, and that a similar improvement in energy is readily achievable by judicious choice of a constant porosity. A more careful comparison, as shown in this paper, suggests only a marginal improvement in energy density. Here, we show the methodology used to reach this conclusion and detail the underlying reason for this result. Rechargeable batteries play an increasingly important role as energy-storage devices, especially as power sources for electric vehicles and for stationary storage of intermittent renewable energy. However, significant increase in energy density and reduction in cost is needed for widespread penetration of storage in these applications. 1 The two strategies that are commonly used to improve the energy density (thereby deceasing the cost) are to develop new materials and/or to develop better electrode/battery designs. The former approach has led to a big focus on next-generation cathodes and anodes for Li-ion batteries, 1-3 and on next generation "beyond Li-ion" systems such as Li-S. 1,4,5 The latter approach, wherein new electrode designs are used to improve the energy density/decrease cost, [6][7][8] is the focus of this paper.A main focus of the efforts related to electrode design is on increasing the thickness of the electrode. This has the effect of decreasing the fraction of inactive mass and volume in the cell (current collectors and separators) thereby providing a straightforward method to increase the energy density. However, as the electrode thickness increases, electrolyte-phase mass transfer limitations become more important impeding the power delivery, thereby leading to an inability to satisfy the requirement of the chosen application. [6][7][8] This interplay between energy and power has resulted in the use of thin (ca. 40 μm) electrodes for high-power applications like hybrid electric vehicles and thick (ca. 80 μm) electrodes for high-energy applications such as electric vehicles. 8 The thickness constraints are acute in Li-ion cells due to the low transport properties of the non-aqueous electrolytes, 8,9 with studies showing that the electrolyte is the main cause of the limitations in these batteri...

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Model-based simultaneous optimization of multiple design parameters for lithium-ion batteries for maximization of energy density

Cited by 81 publications

References 29 publications

Is There a Benefit in Employing Graded Electrodes for Lithium-Ion Batteries?

Is There a Benefit in Employing Graded Electrodes for Lithium-Ion Batteries?

Diffusion‐Limited C‐Rate: A Fundamental Principle Quantifying the Intrinsic Limits of Li‐Ion Batteries

On Graded Electrode Porosity as a Design Tool for Improving the Energy Density of Batteries

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