Boosted by costs benefits, the development of room temperature Na-ion batteries is strongly desired for stationary applications. In this study we explore the possible use of V 2 O 5 aerogel as anode material for sodium ion batteries. The aerogel is able to reversibly insert more than 3 Eq. of sodium in the voltage range 0.1 V-4 V vs. Na/Na + demonstrating to possess additional capacity when cycled to lower voltage. The anode delivers about 200 mAh g −1 in the voltage range 0.01 V-1.5 V vs. Na/Na + . The preliminary characterization of a full Na-ion cell made coupling the V 2 O 5 aerogel anode with carbon-coated Na 3 V 2 (PO 4 In the past years lithium ion batteries (LIBs) have strongly evolved, conquering the market of portable electronic devices and penetrating that of electro-mobility. However, issues related to lithium availability and costs of other materials used in LIBs are rising up. Therefore, special efforts are presently dedicated to the development of alternative battery chemistries based on different shuttling cations like Mg 2+ , 1,2 Al 3+3,4 and Na + . 5,6 In this context, sodium ion batteries (SIBs) are considered as a suitable alternative to the more expensive LIB technology in stationary energy storage applications because their production does not require any technological development aside from the development of appropriate electrodes' materials. In comparison with Li + , the Na + cation is heavier (23 g mol −1 vs 6.94 g mol −1 ) and larger (0.98 Å vs 0.69 Å) leading to lower gravimetric energy and, possibly, slower kinetics. On the other hand, sodium is widely available, therefore, its cost is noticeably low, and worldwide distributed. Moreover, the absence of known Na-Al electrochemically formed alloys permits the use of aluminum current collectors at the anode side, further reducing the cost of the final battery.Presently, the research stream in SIBs' development concerns with the identification of suitable electrode materials taking advantage of the mature background available in lithium ion systems. Several cathode materials are currently investigated, especially those based on layered oxides and polyanionic compounds.6-10 The latter exhibit the advantage of being thermally more stable, 11 thus, enabling safer energy storage.Vanadium-based compounds are of particular interest due to the different oxidation states accessible realizing multi-electrons redox reactions. Indeed, Na 3 V 2 (PO 4 ) 3 is able to reversibly release two equivalents of Na + ions (corresponding to a theoretical capacity of 118 mAh g −1 ), making use of the V 3+ /V 4+ redox couple at around 3.3 V. Additionally, the same material is also investigated as negative electrode as, at 1.5 V, one additional equivalent of Na + is reversibly hosted into the structure while V 3+ is partly reduced to V 2+ . 12 The main drawback of this material is represented by the rather low electronic conductivity, which, however, can be by-passed with the use of nano-sized particles, as well as their carbon-coating. 13Among the layered oxid...

Protic ionic liquid-based electrolytes are promising electrolytes for sodium-ion batteries.

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Nanostructured Li3V2−xNix(PO4)3 (x = 0, 0.05, and 0.1) cathodes, thanks to their high rate capability and excellent cycle stability, are proposed as excellent candidates for the development of high energy and high power density Li-ion asymmetric supercapacitors.

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Non-fluorinated Li3V1.95Ni0.05(PO4)3/C-based electrodes were prepared by using sodium carboxymethyl cellulose, sodium alginate and poly(acrylic acid) as alternative binders of the standard poly(vinylidene difluoride). The effect of the binders was investigated on several aspects, starting from the rheological properties of the dispersions, to the physical-chemical properties of the layers (adhesion test, electrode porosity, surface conductivity). The prepared Li3V1.95Ni0.05(PO4)3/C-based electrodes were characterized as cathodes at different C-rates ranging from 1 C to 200 C in two different potential windows, between 3.0–4.3 and 3.0–4.8 V vs. Li/Li+. The cycle life of the LVNP/C-based electrodes was characterized for each potential window at C-rate as high as 100 C and for 10000 cycles. Electrochemical impedance spectroscopy, scanning electrode microscopy, X-ray diffraction and energy dispersive X-ray measurements were used to study the aged electrodes. Among the electrodes, the one prepared with Na-alginate binder displays the best electrochemical performance, with a specific capacity of 100 and 85 mAh g−1 delivered at 100 C when charged up to 4.3 and 4.8 V vs. Li/Li+, respectively. Moreover, in the same potential windows, it displays an excellent cycling stability over 10000 cycles at 100 C, with a capacity retention of 80% and 65%

This work is dedicated to the memory of Prof. Roberto Marassi, to thank him for his passion and his immeasurable contribution to the research in the electrochemistry field. He also instilled love for Electrochemistry to his research group and his students.Two lithium-ion hybrid supercapacitors (LiHSs) based on high power active materials like Li 3 V 1.95 Ni 0.05 (PO 4 ) 3 /C (LVNP/C), Li 4 Ti 5 O 12 (LTO) and activated carbon (AC) are investigated as high energy and high power devices. Both LiHSs are assembled by using a bi-material negative LTO:AC electrode (50 : 50), able to deliver 38.3 mAh g À 1 at 35 A g À 1 (200 C for LTO), and to retain 80 % of the initial capacity over 10000 cycles at 17.5 A g À 1 . Two positive electrodes are employed in complete devices: a battery-type LVNP/C and a bi-material LVNP/C:AC (65 : 35) based electrodes, for two LiHSs named Hybrid A and Hybrid B, respectively. The energies of the LiHSs are evaluated from 0.05 to 10 A g À 1 , and at different cell voltages (2.6, 2.7 and 2.8 V). The best performance is obtained with Hybrid A cycled between 0-2.7 V, that with 36.3 Wh L À 1 at 4.3 kW L À 1 , possesses an energy density five time higher than that of the AC j j AC (6.8 Wh L À 1 ). Despite both LiHSs charged up to 2.8 V possess superior energy values, at this cell voltage Hybrid A and Hybrid B retain only 11 % and 8 % of the initial capacity cycled over 8000 cycles at 10 A g À 1 , respect to the 75 % and 81 % of the same systems cycled up to 2.7 V.