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[en] Highlights: • Guar gum as aqueous binder for LIB electrodes. • Effect of guar gum on the SEI formed on graphite and NMC. • Mechanical properties of guar gum-based electrodes. - Abstract: Herein we report the investigation on the use of guar gum and two of its derivatives as LIB positive electrodes binders. These polymers are electrochemically stable within the operating voltage of LIBs (0.01–5 V vs Li/Li+) and do not show evidence of thermal decomposition up to 200 °C. The electrochemical performance of lithium nickel manganese cobalt oxide (NMC) electrodes made using guar gum is excellent as indicated, for instance, by the delivered capacity of 100 mAh g−1 upon 5C rate cycling. X-ray Photoelectron Spectroscopy (XPS) measurements of pristine electrodes reveal as the binder layer surrounding the active material particles is thin, resulting in the above-mentioned electrochemical performance. Full lithium-ion cells, utilizing guar gum on both positive and negative electrodes, display a stable discharge capacity of ∼110 mAh g−1 (based on cathode active material) with high coulombic efficiencies. Post-mortem investigation by XPS of cycled graphite electrodes from full lithium-ion cells revealed the formation of a thin solid electrolyte interface (SEI).
[en] In an attempt to realize sodium-ion batteries with enhanced safety, we report herein the utilization of ionic liquid (IL)-based electrolytes for cycling nanoparticulate anatase TiO_2 as sodium-ion anode material. The use of the IL-based electrolyte results in the highly stable cycling performance of anatase TiO_2-based electrodes, providing an initial specific capacity of 159 mAh g"−"1 when applying a specific current of 33.5 mA g"−"1, and still 155 mAh g"−"1 after 80 full (dis-)charge cycles. Moreover, a very promising rate performance is obtained with specific capacities of 108 and 78 mAh g"−"1 for specific currents of 335 and 670 mA g"−"1, respectively. Indeed, the excellent electrochemical performance, and high coulombic efficiency, as well as the electrochemical impedance spectroscopy results indicate the highly beneficial impact of the IL-based electrolyte on the formation of a stabilized solid electrolyte interphase (SEI).