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001015555 001__ 1015555
001015555 005__ 20250929083515.0
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001015555 0247_ $$2Laufende Nummer$$a44573
001015555 0247_ $$2datacite_doi$$a10.18154/RWTH-2025-06437
001015555 037__ $$aRWTH-2025-06437
001015555 041__ $$aEnglish
001015555 082__ $$a621.3
001015555 1001_ $$0P:(DE-82)IDM04094$$aHamzelui, Niloofar$$b0$$urwth
001015555 245__ $$aInvestigation of active materials and polymeric binders in silicon-based negative electrodes for lithium-ion batteries$$cvorgelegt von Niloofar Hamzelui, MSc.$$honline
001015555 260__ $$aAachen$$bInstitute for Power Electronics and Electrical Drives (ISEA), RWTH Aachen University$$c2024
001015555 260__ $$c2025
001015555 300__ $$a1 Online-Ressource : Illustrationen
001015555 3367_ $$02$$2EndNote$$aThesis
001015555 3367_ $$0PUB:(DE-HGF)11$$2PUB:(DE-HGF)$$aDissertation / PhD Thesis$$bphd$$mphd
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001015555 4900_ $$aAachener Beiträge des ISEA$$v191
001015555 500__ $$aVeröffentlicht auf dem Publikationsserver der RWTH Aachen University 2025
001015555 502__ $$aDissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2024$$bDissertation$$cRheinisch-Westfälische Technische Hochschule Aachen$$d2024$$gFak06$$o2024-12-16
001015555 5203_ $$lger
001015555 520__ $$aSilicon (Si) is one of the most promising anode active materials for the next-generation high-energy-density lithium-ion batteries (LIBs), due to its high theoretical capacity compared to state-of-the-art graphite (Gr) anode material. However, the utilization of Si-based anodes in LIBs is limited due to the excessive volumetric changes of Si particles upon lithiation and delithiation. These volume changes lead to particle pulverization, resulting in mechanical degradation, unstable solid electrolyte interphase (SEI), and short cycle life of the battery. To improve the performance of Si-based electrodes, different strategies have been applied. The co-utilization of Si and Gr active materials (Si/Gr composite electrodes) and the development of polymeric binder systems with unique chemistries are two of the most effective strategies to enhance the performance of Si-based anodes. This thesis focuses on the development of Si-based anodes by optimizing the electrode formulations to achieve better mechanical and electrochemical performance. In the first part of this work, a systematic investigation of Si and Gr active material content in the anode, ranging from pure Gr to pure Si, has been conducted using a dual binder system of lithium poly(acrylic acid) (LiPAA) and carboxymethyl cellulose (CMC). The ratio of binders (LiPAA:CMC) was optimized according to the ratio of active materials (Si:Gr). The electrochemical performance of the electrodes was investigated versus lithium (Li) metal and nickel manganese cobalt oxide (NMC622). Post-mortem scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX) was performed on the optimized Si/Gr after lithiation/delithiation at different cycle numbers and C-rates to investigate the changes in morphology and Si particle degradation. The electrochemical performance of the high-capacity Si/Gr and NMC622 cell was investigated and optimized at high temperatures to integrate the cell into a PV-battery system. In the second part of this work, the optimized Si/Gr anode was further studied using sustainable and environmentally friendly natural polymeric binders. Chitosan biopolymers with different degrees of acetylation (DA) and polymerization (DP) were utilized as binders in the Si/Gr anode. After further fine-tuning of the anode formulation with chitosan binders, cross-linking of chitosan with citric acid monohydrate, combined with the development of a free-standing electrode, resulted in improved electrochemical performance of the cell. The electrochemically cycled Si/Gr anodes were analyzed using X-ray photoelectron spectroscopy (XPS) to study the surface chemistry of electrodes with and without chitosan binder. Moreover, the effect of various parameters of the binder solution, such as pH, was investigated for the state-of-the-art LiPAA binder. The mechanical and electrochemical performance of the Si/Gr anodes, as well as the cross-linking of LiPAA with CMC, sodium alginate (SA), and tragacanth gum (TG), was studied. All binders were characterized by Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA), and the mechanical properties of the electrodes were measured by a 90-degree peel test. Based on the electrochemical and mechanical properties of the Si/Gr anodes, the LiPAA binder with a neutral pH exhibited superior performance, especially at higher C-rates. Overall, this work indicates the importance of the anode's chemistry and formulation and its direct effect on the electrochemical performance of the LIBs.$$leng
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001015555 591__ $$aGermany
001015555 7001_ $$0P:(DE-82)IDM04140$$aFiggemeier, Egbert$$b1$$eThesis advisor$$urwth
001015555 7001_ $$0P:(DE-82)1018326$$aWiemhöfer, Hans-Dieter$$b2$$eThesis advisor
001015555 8564_ $$uhttps://publications.rwth-aachen.de/record/1015555/files/1015555.pdf$$yOpenAccess
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001015555 9141_ $$y2024
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001015555 9201_ $$0I:(DE-82)618620_20170609$$k618620$$lLehr- und Forschungsgebiet für Alterungsprozesse und Lebensdauerprognose von Batterien$$x0
001015555 9201_ $$0I:(DE-82)614500_20201203$$k614500$$lInstitut für Stromrichtertechnik und Elektrische Antriebe$$x1
001015555 961__ $$c2025-09-15T14:50:14.964317$$x2025-07-28T23:28:22.071099$$z2025-09-15T14:50:14.964317
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