WEB 3D structured electrodes for Li-ion batteries using open porous metal foams as current collector for high energy applicationThursday (25.06.2020) 09:46 - 09:46 Poster Room Part of:
The demand for Li-ion batteries with ever increasing energy and power densities is not only for automotive applications. Inter alia, high energy density and mechanical stability together with small electrode and cell dimensions are required for medical technology systems or wearable devices. Thus, increasing the areal loading of electrodes is necessary to meet the demands. However, layer thickness and compaction of conventional electrodes cannot be increased arbitrarily since the underlying transport mechanisms as Li-ion and electron transport are limited during charge and discharge. This results in a strong fading of energy and power density at higher current rates, which in turn are necessary for fast charging. A 3D structured electrode design using a metal foam as current collector is regarded to be an alternative approach to overcome these issues.
In comparison to conventional electrodes using a layer of active mass on top of a current collector foil, 3D structured electrodes with an open-porous metal foam as current collector exhibit a 3D connected electronic network within the active material. This shortens the transport pathways of the electrons and lowers the intrinsic resistance of the electrode . Additionally, the high specific surface of the metal foam and consequently large contact area between current collector and active mass leads to an improved charge transfer behavior and Li-ion diffusion [2, 3].
In this study, we investigated different infiltration methods to fabricate NMC based cathodes. A vacuum supported infiltration process will be demonstrated that enables a high active mass loading avoiding cavities after infiltration even for foams with a thickness of up to 1000 µm. We present a detailed microstructure analysis of the foam-based electrodes focusing on (i) the homogeneity of the infiltrated active mass into the open-porous foam structure (ii) the adhesion of the active mass to the metal structure and (iii) the electrolyte accessibility depending on the degree of compaction after drying of the active mass. Therefore, we carried out computer tomography and microscopy analyses of the electrodes. The electrochemical rate capability behavior are finally corresponded to the results of the microstructure analysis.
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 G. F. Yang, K. Y. Song, S. K. Joo, J. Mater. Chem. A, 2 (2014) 19648 - 19652