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Lithium-metal batteries have attracted extensive research attention because of their high energy densities. Developing appropriate electrolytes compatible with lithium-metal anodes is of great significance to facilitate their practical application. Currently used electrolytes still face challenges of high production costs and unsatisfactory Coulombic efficiencies of lithium plating/stripping. In this research, we have developed a diluted electrolyte which is compatible with both lithium-metal anode and sulfurized polyacrylonitrile cathode. It presents a very high Li plating/stripping Coulombic efficiency of 99.3% over prolonged cycling, and the as-assembled anode-free Li-S battery maintains 71.5% of the initial specific capacity after 200 cycles at 0.1 A g−1. This work could shed light on designing a low-cost and high-performance liquid electrolyte for next-generation high-energy batteries. [ABSTRACT FROM AUTHOR]

Rechargeable room‐temperature sodium–sulfur (RT Na–S) batteries are a promising energy storage technology, owing to the merits of high energy density and low cost. However, their electrochemical performance has been severely hindered by the poor compatibility between the existing electrolytes and the electrodes. Here, we demonstrate that an all‐fluorinated electrolyte, containing 2,2,2‐trifluoro‐N,N‐dimethylacetamide (FDMA) solvent, 1,1,2,2‐tetrafluoroethyl methyl ether (MTFE) anti‐solvent and fluoroethylene carbonate (FEC) additive, can greatly enhance the reversibility and cyclability of RT Na–S batteries. A NaF‐ and Na3N‐rich cathode electrolyte interphase derived from FDMA and FEC enables a "quasi‐solid‐phase" Na–S conversion, eliminating the shuttle of polysulfides. The MTFE not only reduces polysulfide dissolution, but also further stabilizes the Na anode via a tailored solvation structure. The as‐developed RT Na–S batteries deliver a high capacity, long lifespan, and enhanced safety. [ABSTRACT FROM AUTHOR]

Wearable electronics require lightweight and flexible batteries, of which lithium‐sulfur (Li‐S) batteries are of great interest due to their high gravimetric energy density. Nevertheless, flexible Li‐S batteries have unsatisfactory electrochemical performance owing to electrode fracture during repeated bending, the volume change of sulfur species and the severe shuttle effect. Binders play essential roles in these batteries but have always lacked attention. Herein, a self‐healing polyvinylpyrrolidone‐polyethyleneimine (PVP‐PEI) binder cross‐linked by hydrogen bonds, which also regulates polysulfide redox kinetics, is reported. The dynamic hydrogen‐bonding networks repair the cracks and ensure the integrity of the electrode while numerous polar groups such as CO and ‐NH2 suppress the shuttle effect by immobilizing polysulfides. Therefore, Li‐S batteries with the PVP‐PEI binder exhibit excellent cycling stability (a capacity decay rate of 0.0718% per cycle at 1 C after 450 cycles), an outstanding areal capacity of 7.67 mAh cm−2 even under a high sulfur loading (7.1 mg cm−2) and relatively lean electrolyte conditions (E/S ratio = 8 µL mg−1). Flexible Li‐S pouch cells using the PVP‐PEI binder show a stable performance for 140 cycles and a favorable capacity retention of over 95% after 2800 bending cycles, confirming its application potential in high‐performance flexible Li‐S batteries. [ABSTRACT FROM AUTHOR]

Pd-encapsulated porous carbon materials (Pd-PCMs) were prepared from the coupling polymerization of an aryl halide and aryl alkyne under mild conditions. Combining its porous microstructure and encapsulated Pd nanoparticles, Pd-PCMs with high sulfur loading reach a capacity of 920 mA h g−1 after 200 cycles at 0.3C. [ABSTRACT FROM AUTHOR]

We find that phenyl diselenide (PDSe) can lower the charge overpotential of Li2S via an inductive effect. The Se–Se bond of PDSe can break when it is in contact with Li2S. The attraction between Se and Li weakens the Li–S bonds and facilitates the oxidation of Li2S in lithium batteries. [ABSTRACT FROM AUTHOR]

Abstract: Due to high energy density, low cost, and nontoxicity, lithium–sulfur (Li–S) batteries are considered as the most promising candidate to satisfy the requirement from the accelerated development of electric vehicles. However, Li–S batteries are subjected to lithium polysulfides (LiPSs) shuttling due to their high dissolution in liquid electrolyte, resulting in low columbic efficiency and poor cycling performance. Moreover, the Li metal as an indispensable anode of Li–S batteries shows serious safety issues derived from the lithium dendrite formation. The replacement of liquid electrolytes with solid‐state electrolytes (SSEs) has been recognized as a fundamental approach to effectively address above problems. In this review, the progress on applying various classes of SSEs including gel, solid‐state polymer, ceramic, and composite electrolytes to solve the issues of Li–S batteries is summarized. The specific capacity of Li–S batteries is effectively improved due to the suppression of LiPSs shuttling by SSEs, while the rate and cycling performance remain relatively poor owing to the limited ionic conductivity and high interfacial resistance. Designing smart electrode/electrolyte integrated architectures, enabling the high ionic transportation pathway and compatible electrode/electrolyte interface, may be an effective way to achieve high performance solid‐state Li–S batteries. [ABSTRACT FROM AUTHOR]

Lithium polysulfide (LiPS) shuttling is one of the main obstacles hindering the practical use of lithium-sulfur (Li-S) batteries. Constructing an interlayer composed of carbon or noncarbon materials on separator is a promising way to restrain the LiPS shuttling, but such a layer always hinders the Li ion diffusion and is hard to realize the reuse of the captured LiPSs. In this study, an in-plane heterostructure constructed by graphene and titanium carbide (TiC) was prepared by directly using graphene as a template and the carbon source to react with TiCl 4 under thermal treatment. In this process, graphene was partially transformed into TiC forming such a heterostructure, which is benefit to reducing the Li ion and electron diffusion barrier. Moreover, the TiC has strong affinity towards LiPSs and high conductivity. Thus, the in-plane heterostructures filtered on a separator as a coating layer effectively blocks the shuttle of LiPSs and greatly improves the sulfur utilization and cycling performance, indicating a promising way to promote the practical applications of high performance Li-S batteries. [ABSTRACT FROM AUTHOR]

Serious shuttle effect of polysulfides is the main obstacle preventing the practical application of lithium sulfur batteries. Herein, we report an ultrathin yet multifunctional polysulfide blocking layer (MPBL) coated on the cathode to effectively restrain the polysulfides shuttling. This MPBL, which was prepared by a simple, one-step electrostatic spray deposition (ESD) technique, was fully and compactly coated on the electrode with controllable thickness, realizing the full protection of the whole cathode. It is noted that the MPBL can be very thin that guarantees the fast ion diffusion but still keeps a high efficiency of blocking polysulfides due to a combination of physical (from carbon) and chemical confinement (from conductive polymer). In addition, the MPBL with good conductivity can act as the upper current collector to reuse the captured polysulfides, and thus improve the sulfur utilization during cycling. With such multifunctional design, the MPBL-coated carbon-sulfur cathode exhibits long cyclic stability and high rate capability, which has only 0.042% capacity decay per cycle at 1C for 1000 cycles and a capacity of 615 mA h g −1 even at a high rate of 3C. [ABSTRACT FROM AUTHOR]

A novel hierarchical porous carbon–carbon nanotube hybrid (HPCC) is prepared using a one-step strategy that uses nickel nanoparticles as the template for pore formation and at the same time, as the catalyst for carbon nanotube (CNT) growth. Such a structure can not only store sulfur in the micro- and mesopores, which restrict the shuttling of polysulfides, but also ensure good electrical conductivity of the whole system due to the incorporation of CNTs. The hierarchical porous structure also ensures fast mass transportation. These factors effectively guarantee the high electrochemical performance of sulfur stored in this carbon in lithium–sulfur batteries. [ABSTRACT FROM AUTHOR]

A carbon-sulfur hybrid with pomegranate-like core-shell structure, which demonstrates a high rate performance and relatively high cyclic stability, is obtained through carbonization of a carbon precursor in the presence of a sulfur precursor (FeS2) and a following oxidation of FeS2 to sulfur by HNO3. Such a structure effectively protects the sulfur and leaves enough buffer space after Fe3+ removal and, at the same time, has an interconnected conductive network. The capacity of the obtained hybrid is 450 mA h g−1 under the current density of 5 C. This work provides a simple strategy to design and prepare various high-performance carbon-sulfur hybrids for lithium-sulfur batteries. [ABSTRACT FROM AUTHOR]

Sheets of Li4Ti5O12 with high crystallinity are coated with nitrogen- doped carbon (NC-LTO) using a controlled process, comprising hydrothermal reaction followed by chemical vapor deposition (CVD). Acetonitrile (CH3CN) vapor is used as carbon and nitrogen source to obtain a thin coating layer of nitrogendoped carbon. The layer enables the NC-LTO material to maintain its sheet structure during the high-temperature CVD process and to achieve high crystallinity. Doping with nitrogen introduces defects into the carbon coating layer, and this increased degree of disorder allows fast transportation of lithium ions in the layer. An electrode of NC-LTO synthesized at 700°C exhibits greatly improved rate and cycling performance due to a markedly decreased total cell resistance and enhanced Li-ion diffusion coefficient (DLi). Specific capacities of 159.2 and 145.8 mAhg-1 are obtained using the NC-LTO sheets, at charge/discharge rates of 1 and 10 C, respectively. These values are much higher than values for LTO particles did not undergo the acetonitrile CVD treatment. A capacity retention value as high as 94.7% is achieved for the NC-LTO sheets after 400 cycles in a half-cell at 5 C discharge rate. [ABSTRACT FROM AUTHOR]

Lithium–sulfur (Li–S) batteries are catching intensive worldwide attention for the outstanding energy density, low‐cost, and nontoxic nature of sulfur. However, the very limited lifespan and rate performance of Li–S systems originating from dissolution and diffusion of long‐chain polysulfides in liquid electrolytes, as well as the intrinsic poor conductivity of sulfur, severely hinder their practical application. Herein, an electrospinning and subsequent dipping and drying method is developed here to fabricate a duplex architecture consisting of reduced graphene oxide (rGO) layer and BaTiO3 (BTO)‐decorated carbon nanofibers (BTO@CNFs), and it is used as a multifunctional interlayer for Li–S batteries. The 3D interwoven CNFs with conductive pathways for both electrons and ions can enhance the contact between polysulfides with BTO nanoparticles and promote the reuse of inactivated sulfur. Additionally, the ferroelectric BTO nanoparticles adhered on CNFs can realize a highly robust trapping to polysulfides via the extremely polar interaction. Moreover, the surface rGO layer can act as a textural barrier to intercept the shuttling polysulfides. Consequently, the modified Li–S batteries with the rGO/BTO@CNF interlayer deliver superior electrochemical performance of 865 mAh g−1 after 200 cycles at 0.3 C and a rate capability of 672 mAh g−1 at 3 C. [ABSTRACT FROM AUTHOR]

The commercialization of high-energy-density and low-cost lithium-sulfur batteries has been severely impeded by capacity fading and electrochemical polarization. Here we report a strategy to entrap polysulfides and boost the cathodic redox kinetics by embedding the surface oxidized quantum-dot-size TiN (TiN-O) within the highly ordered mesoporous carbon matrix. While the carbon scaffold offers sufficient electrical contact to the insulate sulfur, benefiting the full usage of sulfur and physical confinement of polysulfides. The surface oxygen renders TiN-O with a strong charge polarization effect for polysulfides via S-O-Ti bond as verified experimentally and theoretically. The suppressed shuttle effect and high lithium ion diffusion coefficient (7.9 × 10−8 cm2 s−1) lead to a high capacity of 1264 mA h g−1 at 0.2 C with a negligible capacity fading rate of 0.06% per cycle. Additionally, TiN-O based prototype soft-package cells also exhibit excellent cycling stability with flexibility, demonstrating their potential for practical applications. Capacity fading and electrochemical polarization pose barriers to the commercial use of lithium-sulfur batteries. Here the authors show improved charge polarization and electrochemical performance in a surface oxidized quantum-dot-size titanium nitride embedded within a highly ordered mesoporous carbon matrix. [ABSTRACT FROM AUTHOR]

Abstract Highly conductive carbon microspheres (CMSs) with a hierarchical porous structure are prepared by electrospraying polystyrene/polyvinylpyrrolidine (PS/PVP) solution containing Ketjen carbon black (KB) nanoparticles. The branched KB particles serve as the structural skeleton to support CMSs while the hybrid polymer precursor forms multiscale pores upon pyrolysis. The CMSs possessing an extremely large pore volume of 2.08 cm3 g−1 and a large specific surface area of 756 m2 g−1 are melt-infiltrated with sulfur to form sulfur/CMS composite cathode for lithium-sulfur batteries. The cathode delivers a remarkable initial capacity of 1006 mAh g−1 at 1 C with high retention of 67.5% after 1000 cycles, and an initial capacity of 728 mAh g−1 at 2 C with high retention of 68.5% after 2000 cycles. The excellent electrochemical performance is attributed to the distinct functional and structural features of CMS framework: namely, microscale grain size, closely packed KB particles, large pore volume and hierarchical pore size, as well as superior conductive framework, which in turn suppress the shuttling of dissoluble polysulfides and boost the utilization of encapsulated sulfur. The above findings may offer insights into designing new carbon frameworks for other types of high performance rechargeable batteries. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Nitrogen-doped microporous carbon spheres (NPCSs) with a high surface area (1958 m 2 g −1 ), large micropore volume and a high nitrogen content were synthesized by a simple one-step polymerization and subsequent ZnCl 2 activation. The NPCSs can host a large number of small sulfur molecules, and restrict the reaction between the carbonate-based electrolytes and polysulfides. As a result, the NPCSs-sulfur (NPCS S) cathode exhibits excellent cyclic stability (initial capacity of 1382 mAh g −1 and 1002 mAh g −1 after 200 cycles at 0.3 C) and high rate performance (645 mAh g −1 at 3 C) even using the conventional carbonate-based electrolytes, demonstrating its potential use in long-life, safe lithium-sulfur batteries. [ABSTRACT FROM AUTHOR]

A graphene/carbon nanotube (CNT)/sulfur (denoted GCS) hybrid with interconnected structure is prepared through a one-pot self-assembly approach initiated by l -ascorbic acid reduction under a mild condition. In such a solution-based assembly process, the formation of an interconnected graphene/CNT conductive network is accompanied by the uniform loading of sulfur, whose fraction is as high as of 70 wt%. The as-prepared GCS hybrid delivers an initial capacity of 1008 mAh g −1 at 0.3C and maintains 704 mAh g −1 after 100 cycles. Remarkably, at a high rate of 1.0C, the cathode shows an excellent cyclic performance with a capacity of 657 mAh g −1 after 450 ycles and the capacity decay is only 0.04% per cycle. Moreover, the superior rate performance of GCS hybrid is attributed to the conductive network formed by interconnected graphene sheets and CNT, which supply an unimpeded and continuous path for electron and Li ion transfer and accommodate the volume variation of sulfur during charge/discharge cycling. In addition, the residual functional groups on GCS can retain intimate contact of the conducting matrix with sulfur and effectively confine the diffusion of polysulfides. This study gives an eco-friendly and highly effective solution-based approach for carbon–sulfur electrode for lithium–sulfur battery. [ABSTRACT FROM AUTHOR]