Exploiting the high-energy density of lithium metal as a negative electrode for lithium batteries is considered a prerequisite to satisfy the continually increasing demand for extended driving range of electric vehicles and fully electrify our mobility and transportation. However, such lithium-metal batteries face critical safety and life-span concerns. This work outlines a clear route toward realizing safe high-energy-density lithium-metal batteries with excellent cycling stability through the use of a non-flammable and low-volatile ionic liquid electrolyte.

Lithium-rich materials provide the highest specific energies (up to 900 Wh kg −1) among all lithium-ion positive electrode materials. [1] Potentially meeting the high requirements for automotive applications, they receive much attention for use in "next-generation" Li-ion batteries (LIBs). Their large specific capacity originates from the structural peculiarity of lithium-rich layered materials, which can be seen as mixtures of two phases, LiMO 2 (M = Ni, Mn, and Co, rhombohedral R-3m structure) and Li 2 MnO 3 (monoclinic C2/m structure). This latter component provides additional lithium located inside the transition metal layer. [2] However, to access this additional capacity, the Li 2 MnO 3 component must be "activated" by charging to relatively high cutoff voltages (i.e., 4.6-4.8 V). [1a,3] During such activation, Li + ions are extracted from the structure while oxygen anion redox activity occurs possibly through a few different processes. However, transition metal migration into the formed Li vacancies correspondingly occurs, finally resulting in the phase transformation from layered to spinel-like and eventually, rock-salt structure. [4] This is widely regarded as the origin of the two main challenges of lithiumrich materials, that is, voltage and capacity degradation, leading to relatively poor cycle-life. To solve these issues, many strategies have been developed over the past years, which are, for example, modifications of the binder [5] or the electrolyte, [6] and surface treatments [4,7] and lattice doping [8] of the lithium-rich materials. Lattice doping is one of the most suitable methods to address the voltage fading as reported in a few earlier works. Nayak et al. [8b] could maintain higher specific capacity as well as discharge voltage upon cycling, by doping the structure with aluminum (on the account of manganese). This is due to the stabilized surface of the active material and suppressed transformation from layered to spinel-like phase. Chromium has also been adopted as a possible dopant and confirmed to be incorporated into the crystal lattice. It enabled higher average voltage, which was ascribed to a decreased amount of spinel domains generated upon cycling. [9] Moreover, other elements, such as Ti, [10] Mg, [11] and Cu [12] were investigated leading to similar improvements. Besides doping into the transitional metal layer, also lithium site The eco-friendly and low-cost Co-free Li 1.2 Mn 0.585 Ni 0.185 Fe 0.03 O 2 is investigated as a positive material for Li-ion batteries. The electrochemical performance of the 3 at% Fe-doped material exhibits an optimal performance with a capacity and voltage retention of 70 and 95%, respectively, after 200 cycles at 1C. The effect of iron doping on the electrochemical properties of lithium-rich layered materials is investigated by means of in situ X-ray diffraction spectroscopy and galvanostatic intermittent titration technique during the first charge-discharge cycle while high-resolution transmission electron microscopy is used to follow the structural ...

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Ionic liquids (ILs) have been widely explored as alternative electrolytes to combat the safety issues associated with conventional organic electrolytes. However, hindered by their relatively high viscosity, the electrochemical performances of IL‐based cells are generally assessed at medium‐to‐high temperature and limited cycling rate. A suitable combination of alkoxy‐functionalized cations with asymmetric imide anions can effectively lower the lattice energy and improve the fluidity of the IL material. The Li/Li1.2Ni0.2Mn0.6O2 cell employing N‐N‐diethyl‐N‐methyl‐N‐(2‐methoxyethyl)ammonium (fluorosulfonyl)(trifluoromethanesulfonyl)imide (DEMEFTFSI)‐based electrolyte delivered an initial capacity of 153 mAh g−1 within the voltage range of 2.5–4.6 V, with a capacity retention of 65.5 % after 500 cycles and stable coulombic efficiencies exceeding 99.5 %. Moreover, preliminary battery tests demonstrated that the drawbacks in terms of rate capability could be improved by using Li‐concentrated IL‐based electrolytes. The improved room‐temperature rate performance of these electrolytes was likely owing to the formation of Li+‐containing aggregate species, changing the concentration‐dependent Li‐ion transport mechanism.

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Surface repellency of liquid droplets with different surface tensions (23.4-73.2 mN/m) on nanostructured surfaces built of one-and two-tier silica sphere stacking surfaces were investigated, and contact angle hysteresis (CAH) and work of adhesion were analyzed. It was shown that the binary nano-and sub-micrometer-scaled roughened surfaces exhibited better repellency toward oil drops with surface tension of 30 mN/m, and the CAH behavior strongly depended on both liquid types and density of three-phase contact line. This improvement of hysteresis from the two-tier texture is attributed to the facts that (i) the arrangement of submicrometer spheres generates a primary roughness that allows air cushion in the texture and (ii) the deposition of nanospheres creates a large number of point contact fashion to repel the oil penetration, reducing the length of the liquid-solid contact line (i.e., Cassie state). The existing air layer tends to impart the fraction of vapor-solid contact, which decreases the kinetic barrier of drop movement. Incorporated with the Young-Dupre `equation, it has shown a linear relationship between the difference between cosines of advancing and receding angles and the work of adhesion. Accordingly, it reveals that the adhesion of solid-oil contact interface is reduced due to the design of surface topography.

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