05 Fakultät Informatik, Elektrotechnik und Informationstechnik

Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/6

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Institute: search.filters.UBSInstitut.Institut für PhotovoltaikInstitute: search.filters.UBSInstitut.Fakultätsübergreifend / Sonstige EinrichtungStart date: 2020Author: search.filters.author.Biro, DanielSubject: search.filters.subject.333.7

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    Introducing a concept for designing an aqueous electrolyte with pH buffer properties for Zn-MnO2 batteries with Mn2+/MnO2 deposition/dissolution
    (2023) Fitz, Oliver; Wagner, Florian; Pross-Brakhage, Julia; Bauer, Manuel; Gentischer, Harald; Birke, Kai Peter; Biro, Daniel
    For large-scale energy-storage systems, the aqueous rechargeable zinc–manganese dioxide battery (ARZMB) attracts increasing attention due to its excellent advantages such as high energy density, high safety, low material cost, and environmental friendliness. Still, the reaction mechanism and its influence on the electrolyte's pH are under debate. Herein, a pH buffer concept for ARZMB electrolytes is introduced. Selection criteria for pH buffer substances are defined. Different buffered electrolytes based on a zinc salt (ZnSO4, Zn(CH3COO)2, Zn(CHOO)2), and pH buffer substances (acetic acid, propionic acid, formic acid, citric acid, 4-hydrobenzoic acid, potassium bisulfate, potassium dihydrogen citrate, and potassium hydrogen phthalate) are selected and compared to an unbuffered 2 m ZnSO4 reference electrolyte using titration, galvanostatic cycling with pH tracking, and cyclic voltammetry. By adding buffer substances, the pH changes can be reduced and controlled within the defined operating window, supporting the Mn2+/MnO2 deposition/dissolution mechanism. Furthermore, the potential plateau during discharge can be increased from ≈1.3 V (ZnSO4) to ≈1.7 V (ZnSO4 + AA) versus Zn/Zn2+ and the energy retention from ≈30% after 268 cycles (ZnSO4) to ≈86% after 494 cycles (ZnSO4 + AA). Herein, this work can serve as a basis for the targeted design of long-term stable ARZMB electrolytes.
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    Towards sustainable sulfide‐based all‐solid‐state‐batteries : an experimental investigation of the challenges and opportunities using solid electrolyte free silicon anodes
    (2024) Neumann, Tobias; Alexander Dold, Lukas; Thomas Cerny, Alain; Tröster, Eric; Günthel, Michael; Fischer, Anna; Peter Birke, Kai; Krossing, Ingo; Biro, Daniel
    Silicon is one of the most promising anode active materials for future high–energy lithium‐ion‐batteries (LIB). Due to limitations related to volume changes during de-/lithiation, implementation of this material in commonly used liquid electrolyte‐based LIB needs to be accompanied by material enhancement strategies such as particle structure engineering. In this work, we showcase the possibility to utilize pure silicon as anode active material in a sulfide electrolyte‐based all‐solid‐state battery (ASSB) using a thin separator layer and LiNi0.6Mn0.2Co0.2O2 cathode. We investigate the integration of both solid electrolyte blended anodes and solid electrolyte free anodes and explore the usage of non‐toxic and economically viable solvents suitable for standard atmospheric conditions for the latter. To give an insight into the microstructural changes as well as the lithiation path inside the anode soft X‐ray emission and X‐ray photoelectron spectroscopy were performed after the initial lithiation. Using standard electrochemical analysis methods like galvanostatic cycling and impedance spectroscopy, we demonstrate that both anode types exhibit commendable performance as structural distinctions between two‐dimensional and three‐dimensional interfaces became evident only at high charge rates (8 C).