across the whole electrode and suppressed LiPSs shuttling to the lithium anode are required. [8][9][10][11] Great efforts have been made to address these aforementioned issues with a primary focus on the cathode materials. Nano-carbons and graphenes with micro/ mesoporous channels are representative of early stage sulfur host materials, which provide conductivity and physical entrapment of the LiPSs. [12][13][14][15][16][17][18][19] The lack of strong interaction with the LiPSs lead to rapid capacity fading on cycling in most of these studies, however. Functionalized carbons, exemplified by graphene oxides and heteroatoms-doped carbons, demonstrate chemical entrapment of the LiPSs and enable longer-term cycling. [20][21][22][23][24] Modifications of carbons using polymers decorated with polar functional groups established another path to bind LiPSs without compromising the conductivity. [25][26][27] Departing from carbonaceous materials, inorganic metal-based materials including metal oxides, metal sulfides, metal organic frameworks, and MXene phases have been recently studied as sulfur hosts. [28][29][30][31][32][33][34][35] Their strong chemical interaction with LiPSs based on polar-polar interactions, Lewis acid-base bonding or chemical catenation plays an essential role in suppressing the shuttling. Adsorption of LiPSs results in controlled precipitation of Li 2 S and S 8 , which enhances uniform distribution of active materials. [30,36] Aside from the cathode, rationally designed electrolyte modifications and redox mediators have also shown promise in controlling polysulfide dissolution and Li 2 S deposition. [37][38][39][40] In light of the above advances, it is now also appreciated that the low volumetric energy density (ED) of many Li-S batteries still pose a concern due to two aspects: the low density of sulfur (2.07 mg cm −3 ) that is often reported with a high fraction of carbon (>40 wt%), and high electrolyte/sulfur ratios. Achieving high areal sulfur loading (>7 mg cm −2 ) with low electrolyte volume is critical to maximize the ED, but this is not the case for most reported systems to date. [41] Moreover, the challenge for high-performance thick cathodes resides in all cathode components: the individualized nanosized porous C/S composites, the polyvinylidene fluoride (PVDF) binder that lacks elasticity and insufficient interparticle conductivity. [9][10][11] In order to fabricate high-loading Li-S cathodes, two approaches have been used. One is to construct 3D conductive frameworks, [42][43][44][45][46][47] and the other is to integrate the host nanomaterials before slurry processing. [48][49][50] Pure carbon 3D networks, usually composed A comprehensive approach is reported to construct stable and high volumetric energy density lithium-sulfur batteries, by coupling a multifunctional and hierarchically structured sulfur composite with an in-situ cross-linked binder. Through a combination of first-principles calculations and experimental studies, it is demonstrated that a hybrid sulfur host composed b...

We report on the highly stable lithium metal|LiNiCoMnO (NCM 622) cells with practical electrodes' loading of 3.3 mA h g, which can undergo many hundreds of stable cycles, demonstrating high rate capability. A key issue was the use of fluoroethylene carbonate (FEC)-based electrolyte solutions (1 M LiPF in FEC/dimethyl carbonate). Li|NCM 622 cells can be cycled at 1.5 mA cm for more than 600 cycles, whereas symmetric Li|Li cells demonstrate stable performance for more than 1000 cycles even at higher areal capacity and current density. We attribute the excellent performance of both Li|NCM and Li|Li cells to the formation of a stable and efficient solid electrolyte interphase (SEI) on the surface of the Li metal electrodes cycled in FEC-based electrolyte solutions. The composition of the SEI on the Li and the NCM electrodes is analyzed by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. A drastic capacity fading of Li|NCM cells is observed, followed by spontaneous capacity recovery during prolonged cycling. This phenomenon depends on the current density and the amount of the electrolyte solution and relates to kinetic limitations because of SEI formation on the Li anodes in the FEC-based electrolyte solution.

We report on a family of lithium fast ion conductors, Li3+x [Si x P1–x ]­S4, that exhibit an entropically stabilized structure type in a solid solution regime (0.15 < x < 0.33) with superionic conductivity above 1 mS·cm–1. Exploration of the influence of aliovalent substitution in the thermodynamically unstable β-Li3PS4 lattice using a combination of single crystal X-ray and powder neutron diffraction, the maximum entropy method, and impedance spectroscopy reveals that substitution induces structural splitting of the localized Li sites, effectively stabilizing bulk β-Li3PS4 at room temperature and delocalizing lithium ion density. The optimal material, Li3.25[Si0.25P0.75]­S4, exhibits inherent entropic site disorder and a frustrated energy landscape, resulting in a high conductivity of 1.22 mS·cm–1 that represents an increase of three orders of magnitude compared to bulk β-Li3PS4 and one order of magnitude higher than the nanoporous form. The enhanced ion conduction and lowered activation barrier with increasing site disorder as a result of aliovalent “tuning” reveals an important strategy toward the design of fast ion conductors that are vital as solid state electrolytes.

The cathode directs the way to the epimeric menthylamines. The reduction of menthone oxime on a Hg cathode generates (−)‐menthylamine as the major product, whereas a Pb cathode gives access to (+)‐neomenthylamine (see scheme). In situ decoration of the Pb cathode by small amounts of additives results in clean and quantitative conversions. Furthermore, Pb corrosion is completely prevented in this practical method.

The influence of the electrolyte solvents on the cell voltage in lithium-sulfur (Li-S) batteries is investigated. It is found that changing the solvent does not only alter the reaction mechanisms taking place during charge and discharge, but also exerts a pronounced influence on the cell voltage. The changes monitored upon switching from standard ether-based electrolytes to more polar solvents are quite substantial. An increase in the open circuit voltage of up to ∼400 mV could be observed. Both experimental evidence and theoretical calculations are presented in order to elucidate and quantify these effects. It is demonstrated that both the observed trends and the order of magnitude of the measured values can be explained by the free solvation energies of the respective ionic species in the electrolyte systems. Among them, the lithium cation contributes most to the phenomena described. Given that the final reaction products are solid and precipitate from the solution, these effects cannot be exploited to increase the overall energy densities of standard Li-S batteries. However, they are still important both with respect to the fundamental understanding of the electrochemical processes involved as well as practical applications such as liquid, polysulfide-based redox flow batteries.