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    Auger- and X-ray Photoelectron Spectroscopy at Metallic Li Material: Chemical Shifts Related to Sample Preparation, Gas Atmosphere, and Ion and Electron Beam Effects
    (Basel : MDPI, 2022) Oswald, Steffen
    Li-based batteries are a key element in reaching a sustainable energy economy in the near future. The understanding of the very complex electrochemical processes is necessary for the optimization of their performance. X-ray photoelectron spectroscopy (XPS) is an accepted method used to improve understanding around the chemical processes at the electrode surfaces. Nevertheless, its application is limited because the surfaces under investigation are mostly rough and inhomogeneous. Local elemental analysis, such as Auger electron spectroscopy (AES), could assist XPS to gain more insight into the chemical processes at the surfaces. In this paper, some challenges in using electron spectroscopy are discussed, such as binding energy (BE) referencing for the quantitative study of chemical shifts, gas atmospheric influences, or beam damage (including both AE and XP spectroscopy). Carefully prepared and surface-modified metallic lithium material is used as model surface, considering that Li is the key element for most battery applications.
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    MXenes and the progress of Li–S battery development - a perspective
    (Bristol : IOP Publishing, 2021) Balach, Juan; Giebeler, Lars
    Lithium–sulfur (Li–S) battery has attracted tremendous interest owing to its high energy density at affordable costs. However, the irreversible active material loss and subsequent capacity fading caused by the uncontrollable shuttling of polysulfides have greatly hampered its commercial viability. MXenes, a novel class of 2D materials derived from nano-layered MAX phases, have been shown the potential to push the development of sulfur-based batteries to a next level owing to their high conductivity, strong polysulfide affinity and electrocatalytic properties. This perspective article focuses on the possible implications that MXene-based materials will have in the development of advanced sulfur-based batteries and their potential application in different upcoming technologies. In four sections possible developments are outlined which can be reached in the next 10 years, that enable a highly reliable, minimized Li–S battery finally combined with energy harvesters to fabricate autonomous power supplies for the next generation of microscaled devices like meteorological or geotechnical probes, wearable (medical) sensors or other suitable mobile devices. Finally, a flowchart illustrates the possible way to realize some important milestones for the certain possible steps with significant contributions of MXenes.
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    Titanium Niobium Oxide Ti2 Nb10 O29 /Carbon Hybrid Electrodes Derived by Mechanochemically Synthesized Carbide for High-Performance Lithium-Ion Batteries
    (Weinheim : Wiley-VCH, 2021) Budak, Öznil; Srimuk, Pattarachai; Aslan, Mesut; Shim, Hwirim; Borchardt, Lars; Presser, Volker
    This work introduces the facile and scalable two-step synthesis of Ti2 Nb10 O29 (TNO)/carbon hybrid material as a promising anode for lithium-ion batteries (LIBs). The first step consisted of a mechanically induced self-sustaining reaction via ball-milling at room temperature to produce titanium niobium carbide with a Ti and Nb stoichiometric ratio of 1 to 5. The second step involved the oxidation of as-synthesized titanium niobium carbide to produce TNO. Synthetic air yielded fully oxidized TNO, while annealing in CO2 resulted in TNO/carbon hybrids. The electrochemical performance for the hybrid and non-hybrid electrodes was surveyed in a narrow potential window (1.0-2.5 V vs. Li/Li+ ) and a large potential window (0.05-2.5 V vs. Li/Li+ ). The best hybrid material displayed a specific capacity of 350 mAh g-1 at a rate of 0.01 A g-1 (144 mAh g-1 at 1 A g-1 ) in the large potential window regime. The electrochemical performance of hybrid materials was superior compared to non-hybrid materials for operation within the large potential window. Due to the advantage of carbon in hybrid material, the rate handling was faster than that of the non-hybrid one. The hybrid materials displayed robust cycling stability and maintained ca. 70 % of their initial capacities after 500 cycles. In contrast, only ca. 26 % of the initial capacity was maintained after the first 40 cycles for non-hybrid materials. We also applied our hybrid material as an anode in a full-cell lithium-ion battery by coupling it with commercial LiMn2 O4 .