Publications

Publications by the working group led by Prof. Dr. Andrea Balducci since the beginning of their work at the Friedrich Schiller University Jena.

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Highlighted authors are members of the University of Jena.

  1. Monitoring gas evolution during ageing of industrial supercapacitors studied by in situ GC-MS

    Year of publicationPublished in:Energy Storage Materials M. Raidal, R. Kost, T. Makaryan, A. Balducci
    Understanding gas evolution during the ageing of electrical double layer capacitors (EDLCs) is critical for improving long-term performance and safety. However, direct gas analysis in industrial-scale cells has been hindered by their sealed design, complex internal structure, and small gas volumes, limiting broad-component analysis. This study aimed to develop and validate a novel in situ gas chromatography–mass spectrometry (GC–MS) method capable of analysing gas evolution in intact, industrial-format supercapacitor cells under realistic ageing conditions. A custom stainless-steel jig with a detachable gas extraction piece was designed to enable controlled, on-demand sampling from cylindrical EDLCs undergoing an accelerated floating ageing protocol at 3.0 V and 65°C. The system was evaluated for mechanical stability and non-intrusiveness through electrochemical performance metrics and internal pressure monitoring, while extracted gases were analysed qualitatively by GC–MS. The integrated sampling apparatus maintained normal ageing behaviour, with capacitance fading, coulombic efficiency, and logarithmic pressure growth comparable to unmodified cells. The developed in situ GC–MS technique bridges the gap between model-cell studies and real supercapacitor devices, enabling direct correlation of molecular-level gas formation with macroscopic ageing behaviour. This reliable approach provides a versatile platform for investigating alternative electrolytes, electrode materials, and ageing conditions, paving the way for deeper mechanistic understanding of supercapacitor degradation.
    University Bibliography Jena:
    fsu_mods_00029991External link

  2. Method Development for Multidimensional Study of Thermal Aging in Ethyl Isopropyl Sulfone–Electrolyte Supercapacitors

    Year of publicationPublished in:Batteries and supercaps R. Kost, D. Leistenschneider, A. Balducci
    Understanding electrolyte degradation in electric double-layer capacitors (EDLCs) is essential for advancing high-temperature energy storage technologies. In this study, we present a comprehensive methodology to investigate temperature-induced electrolyte aging by correlating electrochemical behavior with molecular (bulk electrolyte) and interfacial (material surfaces) degradation processes. A custom-built Swagelok-type postmortem cell equipped with a quasi-reference silver wire enables simultaneous monitoring of the individual electrode potentials during operation and postaging access to both the liquid electrolyte and electrode surfaces. This integrated design allows for direct linkage between electrochemical response, liquid-phase degradation (via gas chromatography-mass spectrometry), and surface chemistry (via X-ray photoelectron spectroscopy). The methodology is validated across a matrix of electrolytes composed of the 1,1-dimethylpyrrolidinium tetrafluoroborate (Pyr ₁₁ BF ₄ ) salt in either acetonitrile (ACN), the alternative solvent ethyl isopropyl sulfone (EiPS), and an ACN:EiPS 75:25, wt% mixture. All systems were subjected to accelerated aging through 24 h voltage float tests at 3.0 V and three temperatures (20°C, 40°C, and 65°C). By selecting PYR ₁₁ BF ₄ —known for its high electrochemical and thermal stability—the degradation pathways observed can be primarily attributed to solvent effects. This work highlights the critical link between solvent decomposition and electrochemical aging, demonstrating how multidimensional postmortem analysis can guide the development of high-voltage, temperature-stable EDLCs.
    University Bibliography Jena:
    fsu_mods_00029974External link

  3. Improving Electrolyte Sustainability for Sodium-Ion Capacitors by Combining a Bio-Based Solvent With a Low-Fluorine Salt

    Year of publicationPublished in:ChemSusChem :: chemistry & sustainability, energy & materials A. Hainthaler, M. Pinzón, M. Arnaiz, R. Cid, Y. Lu, J. Ajuria, A. Balducci
    This work focuses on improving the sustainability of electrolytes for sodium-ion capacitors (SICs). Through the combination of a low-fluorinated salt, namely sodium difluoro(oxalato)borate (NaDFOB), and the bio-based solvent γ-Valerolactone (GVL), a new electrolyte formulation (1 mol L −¹ NaDFOB in GVL) is being studied for application in SICs. Remarkably, the performance of the SIC full-cells is very comparable to the most commonly used formulation of sodium hexafluorophosphate in ethylene carbonate:propylene carbonate (1 mol L −¹ NaPF ₆ in EC:PC). Furthermore, presodiation strategies were compared for the novel electrolyte system. The in situ oxidation of a sacrificial salt (sodium squarate, Na ₂ C ₄ O ₄ ) incorporated into the positive electrode yielded comparable results to the ex situ electrochemical approach. X-ray photoelectron spectroscopy studies revealed that depending on the presodiation strategy, the solid-electrolyte-interphase composition varies significantly.
    University Bibliography Jena:
    fsu_mods_00030750External link

  4. Temperature effect on hybrid capacitors containing protic acetate-based ionic liquids as electrolytes

    Year of publicationPublished in:Electrochimica acta: the journal of the International Society of Electrochemistry Z. Zheng, D. Leistenschneider, M. Hermesdorf, A. Balducci
    This work reports an investigation about the use of the electrolyte containing 1 M of lithium acetate (LiOAc) in the fluorine-free and low-cost protic ionic liquid 1-methylimidazolium acetate (1-MimOAc) in hybrid capacitors containing lithium iron phosphate (LFP) and activated carbon (AC) electrodes. The physicochemical properties of the electrolyte were first evaluated as a function of temperature, and its electrochemical stability window was determined by linear sweep voltammetry. We show that devices containing this electrolyte display high cycling stability, retaining 75% of their initial capacity after 4000 cycles at 25 °C. In addition, we showed that their performance is affected by the operating temperature. Specifically, at 50 °C, the activated carbon electrode undergoes oxidative surface activation and reduced stability, while at 10 °C, deposition occurs on the surface of the LFP electrode, likely associated with limited ion mobility and altered interfacial changes. These phenomena were examined by SEM, EDX and XPS analyses. These results indicate that different temperature-dependent side reactions dominate at low and high temperatures. Overall, the findings demonstrate that temperature control plays a crucial role in interfacial phase evolution and cycle performance and highlights the potential of acetate-based ionic liquids as a sustainable, fluorine-free hybrid energy storage system.
    University Bibliography Jena:
    fsu_mods_00030084External link

  5. A-Site Vacancy Engineering in KNbO₃ Perovskite for Enhanced Lithium Storage

    Year of publicationPublished in:Chemistry of materials : a publication of the American Chemical Society A. Khan, E. Quarez, N. Dupré, E. Gautron, A. Balducci, O. Crosnier, T. Brousse
    University Bibliography Jena:
    fsu_mods_00024160External link

  6. Simulations of γ-Valerolactone Solvents and Electrolytes for Lithium Batteries Using Polarizable Molecular Dynamics

    Year of publicationPublished in:Molecules: a journal of synthetic chemistry and natural product chemistry A. Pierini, V. Migliorati, J. Gómez-Urbano, A. Balducci, S. Brutti, E. Bodo
    In this paper, we present a molecular dynamics study of the structural and dynamical properties of γ-valerolactone (GVL) both as a standalone solvent and in electrolyte formulations for electrochemistry applications. This study involves developing a new parameterization of a polarizable forcefield and applying it to simulate pure GVL and selected salt solutions. The forcefield was validated with experimental bulk data and quantum mechanical calculations, with excellent agreement obtained in both cases. Specifically, two 1M electrolyte solutions of lithium bis(fluorosulfonyl)imide and lithium bis(oxalate)borate in GVL were simulated, focusing on their ionic transport and highlighting ion solvation structure. Ion pairing in the electrolytes was also investigated through enhanced sampling molecular dynamics, obtaining a detailed picture of the ion dynamics in the GVL solution.
    University Bibliography Jena:
    fsu_mods_00019633External link

  7. Pyrrolidinium-based protic ionic liquid electrolytes for high performance RuO₂ micro-supercapacitors

    Year of publicationPublished in:Electrochimica acta: the journal of the International Society of Electrochemistry J. Seenath, H. Jabraoui, T. Stettner, A. Balducci, A. Estève, D. Pech, D. Rochefort
    University Bibliography Jena:
    fsu_mods_00026971External link

  8. Electrochemical performance of electrochemical double layer capacitors containing pyrrolidinium and ammonium fluorosulfonyl imide in acetonitrile-based electrolytes

    Year of publicationPublished in:Electrochimica acta: the journal of the International Society of Electrochemistry I. Patil, T. Burton, A. Ladam, S. Fantini, A. Balducci
    In this study, we conducted a comprehensive analysis of the chemical-physical properties of electrolytes containing the ionic liquids N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide [Pyr₁₃FSI] and N-trimethyl-N-propylammonium bis (fluorosulfonyl)imide [N₁₁₁₃FSI] dissolved in acetonitrile (ACN). We showed that these innovative electrolytes display favourable transport and thermal properties. When used as electrolytes in electrical double layer capacitors (EDLCs), they allow the realization of devices with excellent energy and power density values, which can be maintained over a wide temperature range. When charge-discharge cycles are carried out, the stability of EDLCs containing these alternative electrolytes is comparable to that of devices containing conventional electrolytes. However, during float tests, their stability is affected by the occurrence of anodic dissolution of the Al current collectors.
    University Bibliography Jena:
    fsu_mods_00023462External link

  9. Dilithium squarate: A game-changing sacrificial salt for pre-lithiation and interphase stabilization in non-SEI forming electrolytes

    Year of publicationPublished in:Chemical Engineering Journal M. Granados-Moreno, R. Cid, M. Arnaiz, J. Gómez-Urbano, A. Balducci, E. Goikolea, J. Ajuria
    University Bibliography Jena:
    fsu_mods_00023540External link

  10. Effect of Water on Local Structure and Dynamics in a Protic Ionic Liquid-Based Electrolyte

    Year of publicationPublished in:ChemSusChem :: chemistry & sustainability, energy & materials F. Lundin, T. Stettner, P. Falus, A. Balducci, A. Matic
    Ionic liquids (ILs) are promising candidates for electrolytes for next-generation energy storage and conversion systems. However, a high viscosity of the IL, hampering the ion transport, has led to strategies based on the dilution of the IL with a low-viscosity solvent. Herein, the influence of the addition of water to a protic IL to form a hybrid electrolyte suggested for supercapacitor applications is reported. The experiments directly test predictions from previous molecular dynamics simulations on this and other protic IL/water hybrid electrolytes. From small-angle X-ray scattering and infrared spectroscopy, it is shown that water is inserted in the ionic matrix both as single molecules and in small aggregates. Water molecules hydrogen bonds to the available proton on the IL cation and effectively separates the ion pairs, resulting in an increase in the charge correlation distance. The change in the local structure is also reflected in the local dynamics probed by neutron spin-echo spectroscopy. A local diffusive-type process is revealed that correlates well with macroscopic ion transport, for example, the ionic conductivity. The results from neutron scattering also infer that the different local environments created by the addition of water have a relatively short lifetime.
    University Bibliography Jena:
    fsu_mods_00024415External link

  11. Glyoxal-based electrolytes for high-power potassium-based systems

    Year of publication L. Meyer
    University Bibliography Jena:
    fsu_mods_00025710External link

  12. Unravelling the mechanism of potassium-ion storage into graphite through electrolyte engineering

    Year of publicationPublished in:Energy Storage Materials L. Meyer, A. Thiagarajan, A. Koposov, A. Balducci
    Graphite is one of the most widely used anode materials in potassium-ion batteries (PIBs). However, the exact mechanism of K⁺ions intercalation into graphite has not yet been fully understood. In addition, the intercalation process strongly depends on the selection of the electrolyte system. In this work, we evaluated the use of an electrolyte containing 1.5 M potassium bis(fluorosulfonyl)imide (KFSI) dissolved in a mixture of propylene carbonate (PC)/ 1,1,2,2-tetraethoxyethane (TEG)/ vinyl ethylene carbonate (VEC) (62:36:2 vol.%). Using such an electrolyte system it was possible to obtain experimental evidence for the formation of KC₁₆ during the potassium intercalation and deintercalation using in situ Raman spectroscopy and operando X-ray diffraction (XRD). The results are supported by the visual observation of a color change of the graphite electrode surface during the intercalation of K⁺ ions into the graphite lattice. In addition, it has been demonstrated that the selected electrolyte system eliminates the co-intercalation of the solvent into the graphite structure.
    University Bibliography Jena:
    fsu_mods_00019256External link
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