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- Kotronia, Antonia
(author)
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Probing Critical Interfaces in Dual-Ion Batteries : The Road Towards Performant Graphite Cathodes
- 2021
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Doctoral thesis (other academic/artistic)abstract
- Transitioning into a zero-emission society will require massive efforts with respect to the harnessing and storage of renewable energy resources. The development of large-scale, electrochemical energy storage systems based on abundant and environmentally benign compounds is seen upon as a key factor for guaranteeing a successful outcome. On these grounds, research into post lithium-ion battery technologies has become increasingly important. Among emerging concepts is that of dual-ion batteries (DIBs); the operational mechanism of which uses both the cation and anion in the electrolyte. DIBs offer some unique advantages compared to other cell chemistries, owing to the unconventional materials combinations they enable. Graphite versus graphite cells constitute a cell chemistry which results in high average voltage (> 4.5 V), decent specific capacity (~100 mAh g-1) and which eliminates transition metals from the cathode. Despite considerable merits, graphite versus graphite dual-ion cells have proven difficult to realize, mainly due to the instability of the cathode electrolyte interface (CEI) at high potentials. This thesis explores critical interfaces in both Li- and K-based DIBs and considers strategies to mitigate these instabilities, based on a combination of electrode and electrolyte engineering. The influence of the electrolyte salt and solvent on the CEI is studied through electrochemical characterization methods and X-ray photoelectron spectroscopy (XPS). Conventional LiPF6-based electrolytes are contrasted to formulations using high concentrations of lithium imide salts such as lithium bis(fluorosulfonyl)imide (LiFSI) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The impact of incorporating functional additives and precycling protocols to reduce electrochemical irreversibility is discussed for Li4Ti5O12‑graphite and MoS2-graphite cells tailored for Li- and K-based DIBs, respectively. In addition, a ternary ionogel is introduced as a novel electrolyte platform for DIBs due to its promising ionic conductivity, oxidative stability and mechanical properties. Finally, the impact of different electrode binders on the surface chemistry and electrochemical performance of the graphite cathode is elucidated. In summary, this work indicated that a passivating, anion conducting CEI is key to enabling dual-ion batteries. Despite the cumbersome nature of this task, ways forward were highlighted both in terms of concrete examples, such as the construction of DIBs incorporating functional additives (e.g. triallyl phosphate) and binders (e.g. poly(vinylidene fluoride-co-hexafluoropropylene)), and in terms of methodology, including the design of reliable cycling protocols to evaluate DIB-performance.
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| 2. |
- Asfaw, Habtom D., 1986-, et al.
(author)
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Charting the course to solid-state dual-ion batteries
- 2024
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In: Carbon Energy. - : John Wiley & Sons. - 2637-9368 .- 2637-9368. ; 6:3
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Research review (peer-reviewed)abstract
- An electrolyte destined for use in a dual-ion battery (DIB) must be stable at the inherently high potential required for anion intercalation in the graphite electrode, while also protecting the Al current collector from anodic dissolution. A higher salt concentration is needed in the electrolyte, in comparison to typical battery electrolytes, to maximize energy density, while ensuring acceptable ionic conductivity and operational safety. In recent years, studies have demonstrated that highly concentrated organic electrolytes, ionic liquids, gel polymer electrolytes (GPEs), ionogels, and water-in-salt electrolytes can potentially be used in DIBs. GPEs can help reduce the use of solvents and thus lead to a substantial change in the Coulombic efficiency, energy density, and long-term cycle life of DIBs. Furthermore, GPEs are suited to manufacture compact DIB designs without separators by virtue of their mechanical strength and electrical performance. In this review, we highlight the latest advances in the application of different electrolytes in DIBs, with particular emphasis on GPEs.
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| 3. |
- Asfaw, Habtom Desta, Dr. 1986-, et al.
(author)
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Tailoring the Microstructure and Electrochemical Performance of 3D Microbattery Electrodes Based on Carbon Foams
- 2019
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In: Energy Technology. - : Wiley. - 2194-4288 .- 2194-4296.
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Journal article (peer-reviewed)abstract
- Three-dimensional (3D) carbon electrodes with suitable microstructural features and stable electrochemical performance are required for practical applications in 3D lithium (Li)-ion batteries. Herein, the optimization of the microstructures and electrochemical performances of carbon electrodes derived from emulsion-templated polymer foams are dealt with. Exploiting the rheological properties of the emulsion precursors, carbon foams with variable void sizes and specific surface areas are obtained. Carbon foams with an average void size of around 3.8 mu m are produced, and improvements are observed both in the coulombic efficiency and the cyclability of the carbon foam electrodes synthesized at 2200 degrees C. A stable areal capacity of up to 1.22 mAh cm(-2) (108 mAh g(-1)) is achieved at a current density of 50 mu A cm(-2). In addition, the areal capacity remains almost unaltered, i.e., 1.03 mAh cm(-2) (91 mAh g(-1)), although the cycling current density increases to 500 mu A cm(-2) indicating that the materials are promising for power demanding applications.
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| 4. |
- Koriukina, Tatiana, 1994-, et al.
(author)
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On the Use of Ti3C2TX MXene as a Negative Electrode Material for Lithium-Ion Batteries
- 2022
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In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 7:45, s. 41696-41710
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Journal article (peer-reviewed)abstract
- The pursuit of new and better battery materials has given rise to numerous studies of the possibilities to use two-dimensional negative electrode materials, such as MXenes, in lithium-ion batteries. Nevertheless, both the origin of the capacity and the reasons for significant variations in the capacity seen for different MXene electrodes still remain unclear, even for the most studied MXene: Ti3C2Tx. Herein, freestanding Ti3C2Tx MXene films, composed only of Ti3C2Tx MXene flakes, are studied as additive-free negative lithium-ion battery electrodes, employing lithium metal half-cells and a combination of chronopotentiometry, cyclic voltammetry, X-ray photoelectron spectroscopy, hard X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy experiments. The aim of this study is to identify the redox reactions responsible for the observed reversible and irreversible capacities of Ti3C2Tx- based lithium-ion batteries as well as the reasons for the significant capacity variation seen in the literature. The results demonstrate that the reversible capacity mainly stems from redox reactions involving the Tx-Ti-C titanium species situated on the surfaces of the MXene flakes, whereas the Ti-C titanium present in the core of the flakes remains electro-inactive. While a relatively low reversible capacity is obtained for electrodes composed of pristine Ti3C2Tx MXene flakes, significantly higher capacities are seen after having exposed the flakes to water and air prior to the manufacturing of the electrodes. This is ascribed to a change in the titanium oxidation state at the surfaces of the MXene flakes, resulting in increased concentrations of Ti(II), Ti(III), and Ti(IV) in the Tx-Ti-C surface species. The significant irreversible capacity seen in the first cycles is mainly attributed to the presence of residual water in the Ti3C2Tx electrodes. As the capacities of Ti3C2Tx MXene negative electrodes depend on the concentration of Ti(II), Ti(III), and Ti(IV) in the Tx-Ti-C surface species and the water content, different capacities can be expected when using different manufacturing, pretreatment, and drying procedures.
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| 8. |
- Kotronia, Antonia, et al.
(author)
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Catalytically graphitized freestanding carbon foams for 3D Li-ion microbatteries
- 2020
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In: Journal of Power Sources Advances. - : Elsevier BV. - 2666-2485. ; 1
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Journal article (peer-reviewed)abstract
- A long-range graphitic ordering in carbon anodes is desirable since it facilitates Li+ transport within the structure and minimizes irreversible capacity loss. This is of vital concern in porous carbon electrodes that exhibit high surface areas and porosity, and are used in 3D microbatteries. To date, it remains a challenge to graphitize carbon structures with extensive microporosity, since the two properties are considered to be mutually exclusive. In this article, carbon foams with enhanced graphitic ordering are successfully synthesized, while maintaining their bicontinuous porous microstructures. The carbon foams are synthesized from high internal phase emulsion-templated polymers, carbonized at 1000 °C and subsequently graphitized at 2200 °C. The key to enhancing the graphitization of the bespoke carbon foams is the incorporation of Ca- and Mg-based salts at early stages in the synthesis. The carbon foams graphitized in the presence of these salts exhibit higher gravimetric capacities when cycled at a specific current of 10 mA g−1 (140 mAh g−1) compared to a reference foam (105 mAh g−1), which amounts to 33% increase.
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| 9. |
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| 10. |
- Kotronia, Antonia, et al.
(author)
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Evaluating electrolyte additives in dual-ion batteries : Overcoming common pitfalls
- 2023
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In: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 459
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Journal article (peer-reviewed)abstract
- Electrolyte additives that form a protective cathode-electrolyte interface (CEI) layer on graphite are sought-after in dual-ion batteries (DIBs). Identifying suitable candidates remains, however, challenging due to lack of universal testing protocols. In this study, specified amounts of vinylene carbonate, fluoroethylene carbonate, lithium bis(oxalato)borate and lithium difluoro(oxalato)borate were added to a 4 M lithium bis(fluorosulfonyl)imide in dimethyl carbonate electrolyte used in Li-graphite and Li4Ti5O12-graphite DIBs. Galvanostatic cycling at 10 mA g−1 resulted in coulombic efficiencies < 90% for all additives and both cell designs, revealing significant irreversibility at the cathode. Self-discharge tests and electrochemical impedance measurements in a three-electrode setup further showed that side-reactions at the graphite electrode induced Li-trapping in Li4Ti5O12. Increasing the specific current to 100-1000 mA g-1 seemingly enhanced the coulombic efficiency (> 98%) and discharge capacity (90-100 mAh g-1), owing to kinetically-suppressed side-reactions. This was hence highlighted as an inappropriate condition to evaluate the additives’ ability to form a passivating CEI. In addition, running such measurements with Li metal as the counter electrode was demonstrated to be problematic, as most additives significantly affected the Li metal plating/stripping, especially for the higher cycling rates.
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