Sodium‐ion batteries are alternatives for lithium‐ion batteries in applications where cost‐effectiveness is of primary concern, such as stationary energy storage. The stability of sodium‐ion batteries is limited by the current generation of electrolytes, particularly at higher temperatures. Therefore, the search for an electrolyte which is stable at these temperatures is of utmost importance. Here, such electrolytes are introduced in the form of nonflammable deep eutectic solvents (DESs), consisting of sodium bis(trifluoromethane)sulfonimide (NaTFSI) dissolved in N‐methyl acetamide (NMA). Increasing the NaTFSI concentration replaces NMA—NMA hydrogen bonds with strong ionic interactions between NMA, Na+, and TFSI−. These interactions lower NMA's highest occupied molecular orbital (HOMO) energy level compared with that of TFSI−, leading to an increased anodic stability (up to ≈4.65 V versus Na+/Na). (Na3V2(PO4)2F3/carbon nanotube [CNT])/(Na2+x Ti4O9/C) full cells show 97.0% capacity retention after 250 cycles at 0.2 C and 55 °C. This is considerably higher than for (Na3V2(PO4)2F3/CNT)/(Na2+x Ti4O9/C) full cells containing a conventional electrolyte. According to the electrochemical impedance analysis, the improved electrochemical stability is linked to the formation of more robust surface films at the electrode/electrolyte interface. The improved durability and safety highlight that DESs can be viable electrolyte alternatives for sodium‐ion batteries.

Radiative Cooling In article number http://doi.wiley.com/10.1002/aesr.202100159, Dries De Sloovere, An Hardy, and co‐workers, show that careful investigation and optimization of the coordination structure of deep eutectic solvents allows the preparation of a viable electrolyte alternative for sodium‐ion batteries. The optimized electrolyte is durable and nonflammable, considerably improving the safety of battery operation. Furthermore, it can offer a more durable electrochemical performance compared to conventional electrolytes.

LiNi0.5Mn1.5O4−δ surface is doped with Ti ion maintaining the spinel structure at 500 °C, higher annealing temperatures cause Ti diffusion from surface towards the core.

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Quasi-spherical undoped ZnO and Al-doped ZnO nanoparticles with different aluminum content, ranging from 0.5 to 5 at% of Al with respect to Zn, were synthesized. These nanoparticles were evaluated as photocatalysts in the photodegradation of the Rhodamine B (RhB) dye aqueous solution under UV-visible light irradiation. The undoped ZnO nanopowder annealed at 400 °C resulted in the highest degradation efficiency of ca. 81% after 4 h under green light irradiation (525 nm), in the presence of 5 mg of catalyst. The samples were characterized using ICP-OES, PXRD, TEM, FT-IR, 27Al-MAS NMR, UV-Vis and steady-state PL. The effect of Al-doping on the phase structure, shape and particle size was also investigated. Additional information arose from the annealed nanomaterials under dynamic N2 at different temperatures (400 and 550 °C). The position of aluminum in the ZnO lattice was identified by means of 27Al-MAS NMR. FT-IR gave further information about the type of tetrahedral sites occupied by aluminum. Photoluminescence showed that the insertion of dopant increases the oxygen vacancies reducing the peroxide-like species responsible for photocatalysis. The annealing temperature helps increase the number of red-emitting centers up to 400 °C, while at 550 °C, the photocatalytic performance drops due to the aggregation tendency.