Multiscale Morphological and Electrical Characterization of Charge Transport Limitations to the Power Performance of Positive Electrode Blends for Lithium‐Ion Batteries

Besnard, Nicolas; Etiemble, Aurélien; Douillard, Thierry; Dubrunfaut, Olivier; Tran-Van, Pierre; Gautier, Laurent; Franger, Sylvain; Badot, Jean-Claude; Maire, Éric; Lestriez, Bernard

doi:10.1002/aenm.201602239

Cited by 79 publications

(87 citation statements)

References 101 publications

(214 reference statements)

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“…Indeed, these parameters can be significantly influenced by blending multiple types of active materials. For example, blending two components with different particle sizes can increase the electrical conductivity of the composite due to an enhanced number of contact points and larger contact areas between the particles because smaller particles fill the cavities between larger particles . The improved electrical conductivity of the composite could compensate or even overcompensate the aforementioned negative effects of blending on the rate capability …”

Section: Resultsmentioning

confidence: 99%

Investigations on the Effective Electric Loads in Blended Insertion Electrodes for Lithium‐Ion Batteries

et al. 2019

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Blending different types of active materials in one electrode is a great opportunity to improve the overall performance of lithium‐ion batteries. Despite considerable progress in the recent years, basic interactions, such as the specific impact of a single component on the blends’ properties, are not satisfactorily understood at the moment. In this study, the electric loads of the individual components of a blend are investigated using a special experimental setup in combination with model‐like blended electrodes. Systematic studies on the impact of type and mass fraction of the components are conducted for different nominal charge and discharge rates. The experiments reveal that the single components can be charged and discharged independent from each other, according to their characteristic redox activities and the overpotential during operation. This can lead to high effective electric loads (C‐rates) subjected to a single component despite a comparatively low total current applied to the electrode. Based on the experimental results, a simple model is developed to estimate maximum effective C‐rates of the individual components in an arbitrary blend system. These novel insights are discussed in regarding advantages and disadvantages of battery electrodes with multiple active materials.

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Section: Resultsmentioning

confidence: 99%

Investigations on the Effective Electric Loads in Blended Insertion Electrodes for Lithium‐Ion Batteries

et al. 2019

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“…Although, increasing the electrode thickness significantly enhances the specific capacity of the electrode up to approximately 100 µm, theoretical [19,[29][30][31][32][33][34] and experimental [35][36][37][38] results clearly show that large electrode thicknesses lead to low rate capability originating from Li + diffusion limitations in the electrolyte. For example, the conductive additive content can be increased until limitations of the electron transport in the composite become negligible.…”

mentioning

confidence: 95%

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

Heubner

Schneider

Michaelis

2019

Advanced Energy Materials

124

103

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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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“…The amount of binder that is adsorbed on the particles in the slurry depends on the polymer molecular structure, the solvent properties and the surface chemistry of the particles. [40,41] In this work, we study a simple postprocessing treatment that improves very significantly the cohesion and adhesion strengths of composite electrodes, which also results in a significant electrochemical performance gain, up to a factor 10. [35,36] The drying step plays a critical role as the free binder remaining in the solvent can migrate with the solvent toward the top surface of the electrode film.…”

Section: Introductionmentioning

confidence: 99%

A Facile and Very Effective Method to Enhance the Mechanical Strength and the Cyclability of Si‐Based Electrodes for Li‐Ion Batteries

Hernandez

Etiemble

Douillard

et al. 2017

Advanced Energy Materials

Self Cite

130

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It is well known that the mechanical properties of lithium‐ion battery electrodes impact their electrochemical performance. This is especially critical for Si‐based negative electrodes, which suffer from large volume changes of the active mass upon cycling. Here, this study presents a postprocessing treatment (called maturation) that improves the mechanical and electrochemical stabilities of silicon‐based anodes made with an acidic aqueous binder. It consists of storing the electrode in a humid atmosphere for a few days before drying and cell assembly. This results in a beneficial in situ reactive modification of the interfaces within the electrode. First, the binder tends to concentrate at the silicon interparticle contacts. As a result, the cohesion of the composite film is strengthened. Second, the corrosion of the copper current collector, inducing the formation of copper carboxylate bonds, improves the adhesion of the composite film. The great improvement of the mechanical stability of the matured electrode is confirmed by in‐operando optical microscopy showing the absence of film delamination. The result is a significant electrochemical performance gain, up to a factor 10, compared to a not‐matured electrode. This maturation procedure can be applied to other types of electrodes for improving their electrochemical performance and also their handling during cell manufacturing.

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Multiscale Morphological and Electrical Characterization of Charge Transport Limitations to the Power Performance of Positive Electrode Blends for Lithium‐Ion Batteries

Cited by 79 publications

References 101 publications

Investigations on the Effective Electric Loads in Blended Insertion Electrodes for Lithium‐Ion Batteries

Investigations on the Effective Electric Loads in Blended Insertion Electrodes for Lithium‐Ion Batteries

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

A Facile and Very Effective Method to Enhance the Mechanical Strength and the Cyclability of Si‐Based Electrodes for Li‐Ion Batteries

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