A composite electrode model for lithium-ion batteries with silicon/graphite negative electrodes

Ai, Weilong; Kirkaldy, Niall; Jiang, Yang; Offer, Gregory J.; Wang, Huizhi; Wu, Billy

doi:10.1016/j.jpowsour.2022.231142

Cited by 43 publications

(26 citation statements)

References 36 publications

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“…An appreciable amount of LAM-Si is also observed in the cells aged over the 0–100% SoC range, for which both the Si and Gr components are electrochemically cycled (note the different y-scales for LAM-Si and LAM-Gr on Figure ). The high degree of LAM-Si relative to LAM-Gr may be caused by a variety of reasons: first, that the rate of Si degradation is inherently faster than that of Gr, in part due to the large volume changes experienced by Si upon (de)lithiation; second, due to the fact that the silicon particles experience far greater current densities than the graphite particles . This is an unavoidable problem faced by composite electrodes, resulting from the fact that the electrochemically active surface area of Si is significantly smaller than that of Gr for the material ratios usually used.…”

Section: Resultsmentioning

confidence: 99%

“…The high degree of LAM-Si relative to LAM-Gr may be caused by a variety of reasons: first, that the rate of Si degradation is inherently faster than that of Gr, in part due to the large volume changes experienced by Si upon (de)lithiation; second, due to the fact that the silicon particles experience far greater current densities than the graphite particles. 45 This is an unavoidable problem faced by composite electrodes, resulting from the fact that the electrochemically active surface area of Si is significantly smaller than that of Gr for the material ratios usually used. Higher current densities lead to larger concentration gradients and increased rates of degradation.…”

Section: Resultsmentioning

confidence: 99%

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Lithium-Ion Battery Degradation: Measuring Rapid Loss of Active Silicon in Silicon–Graphite Composite Electrodes

Kirkaldy

Samieian

Offer

et al. 2022

ACS Appl. Energy Mater.

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To increase the specific energy of commercial lithium-ion batteries, silicon is often blended into the graphite negative electrode. However, due to large volumetric expansion of silicon upon lithiation, these silicon–graphite (Si–Gr) composites are prone to faster rates of degradation than conventional graphite electrodes. Understanding the effect of this difference is key to controlling degradation and improving cell lifetimes. Here, the effects of state-of-charge and temperature on the aging of a commercial cylindrical cell with a Si–Gr electrode (LG M50T) are investigated. The use of degradation mode analysis enables quantification of separate rates of degradation for silicon and graphite and requires only simple in situ electrochemical data, removing the need for destructive cell teardown analyses. Loss of active silicon is shown to be worse than graphite under all operating conditions, especially at low state-of-charge and high temperature. Cycling the cell over 0–30% state-of-charge at 40 °C resulted in an 80% loss in silicon capacity after 4 kA h of charge throughput (∼400 equiv full cycles) compared to just a 10% loss in graphite capacity. The results indicate that the additional capacity conferred by silicon comes at the expense of reduced lifetime. Conversely, reducing the utilization of silicon by limiting the depth-of-discharge of cells containing Si–Gr will extend their lifetime. The degradation mode analysis methods described here provide valuable insight into the causes of cell aging by separately quantifying capacity loss for the two active materials in the composite electrode. These methods provide a suitable framework for any experimental investigations involving composite electrodes.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Lithium-Ion Battery Degradation: Measuring Rapid Loss of Active Silicon in Silicon–Graphite Composite Electrodes

Kirkaldy

Samieian

Offer

et al. 2022

ACS Appl. Energy Mater.

Self Cite

View full text Add to dashboard Cite

show abstract

“…The high degree of LAM-Si relative to LAM-Gr may be caused by a variety of reasons: firstly, that the rate of Si degradation is inherently faster than that of Gr, in part due to the large volume changes experienced by Si upon (de)lithiation; secondly, due to the fact that the silicon particles experience far greater current densities than the graphite particles. 43 This is an unavoidable problem faced by composite electrodes, resulting from the fact that the electrochemically active surface area of Si is significantly smaller than that of Gr for the material ratios usually used. Higher current densities lead to larger concentration gradients and increased rates of degradation.…”

Section: And Ohmic Resistance Increase (C and D) Vs Charge Throughput...mentioning

confidence: 99%

Lithium-Ion Battery Degradation: Measuring Rapid Loss of Active Silicon in Silicon-Graphite Composite Electrodes

Kirkaldy

Samieian

Offer

et al. 2022

Preprint

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In an effort to increase the specific energy of lithium-ion batteries, silicon additives are often blended with graphite (Gr) in the negative electrode of commercial cells. However, due to the large volumetric expansion of silicon upon lithiation, these Si-Gr composites are prone to faster rates of degradation than conventional graphite electrodes. Understanding the effect of this difference is key to controlling degradation and improving cell lifetimes. Here, we investigate the effects of state of charge and temperature on the ageing of a commercial cylindrical cell with a Si-Gr electrode (LG M50T). Using degradation mode analysis, we were able to quantify the rates of degradation for Si and Gr separately. Loss of active Si is shown to be worse than Gr under all operating conditions, but especially at low state of charge and high temperature, with up to 80% loss in Si capacity after 4 kA h of charge throughput (~400 equivalent full cycles). The results indicate cell lifetimes can be improved by limiting the depth of discharge of cells containing Si-Gr, which suggests Si is not beneficial for all applications. The degradation mode analysis methods developed here provide valuable new insight into the causes of cell ageing by separating the effects of the two active materials in the composite electrode. These methods provide a suitable framework for data analysis of any experimental investigations on cells involving composite electrodes.

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“…Within a porous electrode, lithium ions travel through the solution phase [11][12][13][14][15] , and electrons travel through the solid matrix [16,17] , which is typically composed of AM particles blended in a mixture of conductive carbon [18][19][20] additive and a relatively lower conductive polymer [21] based binder. When charging [22,23] , lithium ions and electrons react at the surface of the AM at the cathode, forming liquid phase lithium ion complexes that diffuse through the liquid phase of the porous electrode, and at the anode, these lithium ions react at the surface of the AM to diffuse into the AM lattice. Understanding the interplay between these various electrochemical reactions and transport processes is key to designing batteries with performance characteristics that can meet automotive and consumer electronic characteristics.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Multi-Dimensional Numerical Transport Study of Lithium-Ion Battery Active Material Microstructures for Automotive Applications

et al. 2022

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Conventional porous electrode battery modeling for a variety of applications makes assumptions to reduce the complexity of the simulation where tradeoffs between computational complexity and electrode detail can be realized without significantly impacting the accuracy of the results. The most common porous electrode battery model is the pseudo-two-dimensional (P2D) model as popularized by Newman and colleagues. These porous electrode battery models typically focus on simulating gradients in two dimensions; the primary dimension through the thickness of the battery cell electrodes and separators, and the secondary dimension in the radial direction of spherical active material particles. The particles are distributed throughout what is assumed to be a homogeneous porous electrode domain. Typically, uniformity in particle size, porosity, and tortuosity is assumed. In this work, the development of a three-dimensional microstructure (3DMS) lithium-ion battery model will be presented. With the increase in computational resources available in academia and industry, simulation of the microstructure in 3D is possible. Active material domains of both the anode and cathode can be generated stochastically to create microstructures representing the electrodes, with voids surrounding the particle representing the electrolyte. A comparison between the P2D and 3DMS models with sensitivity analysis focused on items that can be probed with microstructure simulations will be discussed and similarities and/or differences in charge/discharge characteristics, overpotentials, and concentration profiles will be presented. The findings from this work will provide a path to simulate at the microstructure level, drive electrode design, and translate the effects of heterogeneity into a homogenous porous electrode model.

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A composite electrode model for lithium-ion batteries with silicon/graphite negative electrodes

Cited by 43 publications

References 36 publications

Lithium-Ion Battery Degradation: Measuring Rapid Loss of Active Silicon in Silicon–Graphite Composite Electrodes

Lithium-Ion Battery Degradation: Measuring Rapid Loss of Active Silicon in Silicon–Graphite Composite Electrodes

Lithium-Ion Battery Degradation: Measuring Rapid Loss of Active Silicon in Silicon-Graphite Composite Electrodes

Dynamic Multi-Dimensional Numerical Transport Study of Lithium-Ion Battery Active Material Microstructures for Automotive Applications

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