Here we demonstrate pronounced suppression of self-discharge using an ionic liquid of N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl)imide-based electrolytes for Li–S batteries.

the charge process, and this is considered to be another factor contributing to the rapid decay of Li-S batteries.Recently, it has been reported that nitrogen-doped carbon exhibits strong chemisorption for polysulfi des and Li 2 S, and consequently longer cycling performance has been achieved by developing N-doped carbon/S composites. [ 10 ] It has been demonstrated that the electronegative N atoms in the carbon matrix are particularly effective in forming S x Li⋅⋅⋅N interactions via the lone-pair electrons of N because of the strong interaction due to Lewis acid-base interaction between Li + cations in Li 2 S x and N atoms in the carbon matrix. [ 10 ] Alternatively, boron atoms, as an electron-defi cient alternative to N atoms, are electropositive in the carbon framework, thus leading to the chemisorption of polysulfi de anions (S x 2− ). [ 11 ] Accordingly, it was reported very recently that a boron-doped carbon host can also improve the performance of S composite cathodes. [ 11 ] As reviewed above, recent carbon host design strategies based on the enhanced chemisorption of lithium polysulfi de (Li 2 S x , 4 ≤ x ≤ 8) and Li 2 S rely solely on either the chemisorption of Li + cations in Li 2 S and lithium polysulfi des at negatively polarized N atoms or on the chemisorption of polysulfi des anion at positively polarized B atoms. If N atoms and B atoms are both introduced into the carbon, the chemical adsorption for both Li + cations and polysulfi des anions can be increased simultaneously, which may further enhance the cycling performance of the C/S composite cathode. We especially note that if the B atoms are adjacent to the N atoms to form an N = B/N-B structure in the carbon framework, the polarization of both B atoms and N atoms will be further enhanced because the electronegativity of a N atom is higher than that of a C atom, whereas the electronegativity of a B atom is lower than that of a C atom. Therefore, it is expected that an N = B/N-B structure in a carbon framework will exhibit much higher chemisorption for both lithium polysulfi des and Li 2 S. Hence, we present a strategy to chemically bind sulfur and its discharge products with a graphene-supported N/B codoped carbon layer with unique N = B/N-B sites and various kinds of N sites (pyrrolic N and pyridinic N) in the surface carbon framework.It would be a great challenge to synthesize the N = B/N-B structure by introducing the N and B separately into carbon framework because of the low percentage of heteroatoms in N/B-doped carbon materials. Therefore, our synthetic strategy is quite different. In our strategy, ionic liquid (IL, in particular [Emim]BF 4 ) was fi rst introduced to functionalize a graphitic The high theoretical energy density (2600 Wh kg −1 ) and the low cost of sulfur have made lithium-sulfur (Li-S) batteries an attractive option to satisfy the need for advanced energy storage. [ 1 ] However, there are several challenges. Foremost among these is the shuttling effect arising from the dissolution of lithium polysulfi des intermediat...

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A new versatile single-ion electrolyte with a Grotthuss-like Li conduction mechanism is proposed to address the issue of Li metal batteries.

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Carbon/sulfur composites are attracting extensive attention because of their improved performances for Li–S batteries. However, the achievements are generally based on the low S‐content in the composites and the low S‐loading on the electrode. Herein, a leaf‐like graphene oxide (GO), which includes an inherent carbon nanotube midrib in the GO plane, is synthesized for preparing GO/S composites. Owing to the inherent high conductivity of carbon nanotube midribs and the abundant surface groups of GO for S‐immobilization, the composite with an S‐content of 60 wt% exhibits ultralong cycling stability over 1000 times with a low capacity decay of 0.033% per cycle and a high rate up to 4C. When the S‐content is increased to 75 wt%, the composite still shows a perfect cycling performance over 1000 cycles. Even with the high S‐loading of 2.7 mg cm−2 on the electrode and the high S‐content of 85 wt%, it still shows a promising cycling performance over 600 cycles.

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The development of Li metal anodes is hindered by the Li dendrites arising from the random deposition of Li metal during cycles. Hence, uniform deposition of Li during repeated cycles is crucial for the development of Li metal batteries. However, it is difficult to regulate Li deposition because of convection in the electrolyte. Here, we employ a dual lithiophilic structure composed of a polar metal–organic framework (MOF) and highly conductive Ag nanoparticles, and we show that it brings about uniform lithium deposition. The binding energy for Li is increased by the abundant oxygen sites and large surface area of the MOF, and concomitantly, the uniform distribution of Li nuclei can be achieved with a low nucleation overpotential. When highly conductive lithiophilic Ag is incorporated into the MOF, the binding energy for Li is further increased and the nucleation overpotential is decreased to nearly zero. As a result, Li platting and stripping on the Ag@MOF (i.e., Ag@HKUST-1) substrate exhibit a Coulombic efficiency of 97% over 300 cycles and a high areal capacity of 5 mA h cm–2 without dendrite formation.