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The complex system of interfaces at the electrodes of a lithium-ion battery is an important basis for the performance and ageing behaviour of lithium-ion batteries. The transport of ions takes place at the electrode-electrolyte interfaces at both electrodes through interphases, which form due to the thermodynamic instability of the electrolyte or are artificially generated. Ideally, these interphases only transport ions. However, they also contribute to the secondary reaction with the electrolyte through electron and molecule transport and thus to the ageing of the battery. Furthermore, interphases can also hinder electron transport from the current collector to the active material, for example at the interface between the current collector and the active material.
In this work, two aspects of interfacial transport in lithium-ion battery electrodes are investigated using model systems. On the anode side, glassy carbon serves as a substrate for the formation of model solid electrolyte interphases (SEI). Irreversible redox probe experiments are used to investigate molecular transport in the solid electrolyte interphase. By using the additive PES, a contrast could be created within the SEI. TOF-SIMS investigations confirm the electrolyte diffusion model, according to which electrolyte molecules diffuse through pores in the SEI to the electrode material and are reduced there (bottom-up mechanism). On the cathode side, LMNO was used in conjunction with lithium niobate coating. Here, the electrochemical behaviour was characterised as a function of the pre-treatment temperature of the niobate coating. A strong influence on the cell impedance was demonstrated and clarified. Although the charge transfer of the lithium ions was optimised, a greater effect was found on a second interface on the current collector. Using impedance spectroscopy and electron microscopy, the formation of an apparently neglected interphase on the aluminium current collector was detected. This causes a contact resistance that can have a considerable influence on the cell impedance. Coatings and electrolyte additives were used to mitigate secondary reactions of the electrolyte, which accelerate the corrosion of the current collector through HF formation.
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Issued: 2024-12-12
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FB15:Chemie
Language
en
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Battery
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Pateras Pescara, Lars: Characterization of Electrode-Electrolyte Interphases. : 2024-12-12. DOI: https://doi.org/10.17192/openumr/303.
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Except where otherwised noted, this item's license is described as Attribution 3.0 Germany