Investigation of film solidification and binder migration during drying of Li-Ion battery anodes

Jaiser, S.; Müller, Marcus; Baunach, Michael; Bauer, Werner; Scharfer, Philip; Schabel, Wilhelm

doi:10.1016/j.jpowsour.2016.04.018

Cited by 229 publications

(368 citation statements)

References 40 publications

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“…Clearly, simply increasing the lower layer binder concentration could not slow down binder migration towards the electrode surface. The results obtained from EDS analysis of fluorine concentration distribution of the dried cathode samples were consistent with that presented by Jaiser et al …”

Section: Resultssupporting

confidence: 91%

“…Jaiser et al. studied the distribution of binding agent and conductive additives in an anode by means of energy‐dispersive X‐ray spectroscopy (EDS) to measure fluorine concentrations at the upper and lower surfaces of an anode . They observed that, when the sample was dried at a high drying rate, the fluorine concentration at the top surface was higher than that at the bottom surface.…”

Section: Introductionmentioning

confidence: 99%

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Improvement of Lithium‐Ion Battery Performance by Two‐Layered Slot–Die Coating Operation

et al. 2017

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The cathode and anode electrodes in lithium‐ion batteries typically contain a significant proportion of particles and binders. During the electrode drying process, high temperature will lead to the binder migration phenomenon. Uneven particle/binder distribution can cause poor adhesion between coating and substrate, disruption of conductive paths, and decrease in electrode performance. In this study, a two‐layered cathode was designed by using separate compositions of slurry ingredients in each layer, as produced by means of a simultaneous multilayer coating method. The two‐layered cathode with the top layer containing less binder than the bottom layer yielded a better particle/binder distribution in the final structure under high‐temperature drying. A battery made with the two‐layered cathode appeared to give a better overall performance.

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Section: Resultssupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Improvement of Lithium‐Ion Battery Performance by Two‐Layered Slot–Die Coating Operation

et al. 2017

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“…The pronounced effect of the small volume fraction binder phase was previously shown for inhomogeneous binder distributions prepared by different drying procedures. 9 More detailed investigations of the electrode preparation steps and their influence on electrode tortuosity will be subject of a future work.…”

Section: Resultsmentioning

confidence: 99%

Influence of the Binder on Lithium Ion Battery Electrode Tortuosity and Performance

Landesfeind

Eldiven

Gasteiger

2018

J. Electrochem. Soc.

106

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The electrochemical performance of porous graphite anodes in lithium ion battery applications is limited by the lithium ion concentration gradients in the liquid electrolyte, especially at high current densities and for thick coatings during battery charging. Beside the electrolyte transport parameters, the porosity and the tortuosity of the coating are key parameters that determine the electrode's suitability for high power applications. Here, we investigate the tortuosity of graphite anodes using two water as well as three n-methyl-2-pyrrolidone based binder systems by analysis of symmetric cell impedance measurements, demonstrating that tortuosities ranging from ∼3-10 are obtained for graphite anodes of similar thickness (∼100 μm), porosities (∼50%) and areal capacity (∼3.4 mAh/cm 2 ). Furthermore, selected electrodes with tortuosities of 3.1, 4.3, and 10.2 were cycled in cells with reference electrode at charging C-rates from 0. Understanding and predicting rate limitations in lithium ion batteries with porous electrodes requires profound knowledge of not only the electrolyte transport parameters (i.e., transference number, diffusion coefficient, conductivity) and the thermodynamic factor, but also the porosity and the tortuosity of the electrodes. The tortuosity of the electrode is particularly critical because the effective electrolyte conductivity and the effective diffusion coefficient in the electrolyte directly scale with the inverse of the tortuosity, so that care has to be taken to develop electrodes with minimized tortuosity. Using experimental approaches 1-4 or 3D tomography, 5,6 it was shown that the shape of active material particles distinctly influences the electrode tortuosity. For a given active material, however, electrode tortuosity and rate capability can also be improved by the design of the electrode layer such that short diffusion distances can be obtained across the electrode. For example, improved performance was demonstrated for graphite anodes when the platelet graphite particles were aligned normal to the current collector surface by means of a magnetic field 7 or when silicon/graphite anode electrodes were laser structured. 8 In this study we focus on the role of the electrode composition, specifically the role of the binder, on its tortuosity as well as on its implication for battery performance. While in the literature the link between binder and electrochemistry is frequently studied empirically using rate capability tests 9 and long-term cycling experiments, 10-13 we focus on the correlation of electrode tortuosity with binder content/type and its effect on rate capability.In the following, the tortuosity of graphite anodes with different binders, different binder contents, and different amounts of conductive carbon additive will be determined by electrochemical impedance spectroscopy (EIS) of symmetric cells using the transmission line model approach. 3,14 In the first part of our analysis we will demonstrate the effect of binder and conductive carbon additives on electrode t...

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“…Between casting and film solidification, the particles and the binder are still mobile, and hence, material redistribution may occur . For instance, Schabel and co‐workers recently reported on the mobility of PVdF and mixtures of CMC‐Na and SBR in graphite slurries depending on the drying conditions . The maximum tensile forces for the three electrode formulations are shown in Figure .…”

Section: Resultsmentioning

confidence: 99%

Water‐Soluble Binders for Lithium‐Ion Battery Graphite Electrodes: Slurry Rheology, Coating Adhesion, and Electrochemical Performance

et al. 2017

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Water‐processable composite electrodes are attractive both ecologically and economically. The binders sodium carboxymethyl cellulose (CMC‐Na) and poly(sodium acrylate) (PAA‐Na) were shown to have improved electrochemical performance over conventional binders. In many studies, a binder content of approximately 10 wt % has been applied, which is not suitable for large‐scale electrode production due to viscosity and energy‐density considerations. Therefore, we examined herein three electrode formulations with binder contents of 4 wt %, namely, CMC‐Na:SBR (SBR=styrene butadiene rubber), PAA‐Na, and CMC‐Na:PAA‐Na, on both laboratory and pilot scales. The formulations were evaluated on the basis of slurry rheology, coating adhesion, and electrochemical behavior in half‐ and full‐cells. CMC‐Na:SBR composites provided the best coating adhesion, independent of the mass loading and scale, and also showed the best capacity retention after 100 cycles. Previously reported merits of better cycling efficiencies and solid–electrolyte interphase formation for graphite–PAA composites appeared to vanish upon reducing the binder content to realistic levels.

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Investigation of film solidification and binder migration during drying of Li-Ion battery anodes

Cited by 229 publications

References 40 publications

Improvement of Lithium‐Ion Battery Performance by Two‐Layered Slot–Die Coating Operation

Improvement of Lithium‐Ion Battery Performance by Two‐Layered Slot–Die Coating Operation

Influence of the Binder on Lithium Ion Battery Electrode Tortuosity and Performance

Water‐Soluble Binders for Lithium‐Ion Battery Graphite Electrodes: Slurry Rheology, Coating Adhesion, and Electrochemical Performance

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