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Lithium‐sulfur (Li‐S) batteries have received tremendous academic and industrial attentions owing to their ultrahigh energy density. However, technical challenges including lithium dendrite formation, polysulfide shuttling and sluggish sulfur reaction kinetics limit their cycle life, rate capability and areal capacity, especially at practically high sulfur loadings. Here, coordination‐engineered graphite carbon nitrides is proposed to effectively address these challenges. On the anode a layer of novel N‐rich graphitic carbon nitride (g‐C3N5) is applied, in which tricoordinated N atoms display strong affinity to Li+, to guide lithium deposition and efficiently inhibit dendrite formation. Besides, a layer of defective g‐C3N5 carrying highly active bicoordinated N vacancies and cyano N atoms is applied on the cathode, which significantly adsorb polysulfides and catalyze the reversible conversion, as well as the nucleation and dissolution of Li2S thereby outcompeting polysulfide shuttling and raising kinetics at high sulfur loading. This coordination‐engineering strategy based on g‐C3N5 enables Li‐S batteries exhibiting high stability and low capacity‐fading‐rate (0.03% per cycle) in 400 cycles at the high current rate of 4 C, as well as Li‐S pouch cells showing a high areal capacity of 11.69 mAh cm−2 at a high sulfur loading of 9.02 mg cm−2, demonstrating the feasibility of Li‐S batteries in practical applications. [ABSTRACT FROM AUTHOR]

The sluggish kinetics of complicated multiphase conversions and the severe shuttling effect of lithium polysulfides (LiPSs) significantly hinder the applications of Li‐S battery, which is one of the most promising candidates for the next‐generation energy storage system. Herein, a bifunctional electrocatalyst, indium phthalocyanine self‐assembled with carbon nanotubes (InPc@CNT) composite material, is proposed to promote the conversion kinetics of both reduction and oxidation processes, demonstrating a bidirectional catalytic effect on both nucleation and dissolution of Li2S species. The theoretical calculation shows that the unique electronic configuration of InPc@CNT is conducive to trapping soluble polysulfides in the reduction process, as well as the modulation of electron transfer dynamics also endows the dissolution of Li2S in the oxidation reaction, which will accelerate the effectiveness of catalytic conversion and facilitate sulfur utilization. Moreover, the InPc@CNT modified separator displays lower overpotential for polysulfide transformation, alleviating polarization of electrode during cycling. The integrated spectroscopy analysis, HRTEM, and electrochemical study reveal that the InPc@CNT acts as an efficient multifunctional catalytic center to satisfy the requirements of accelerating charging and discharging processes. Therefore, the Li–S battery with InPc@CNT‐modified separator obtains a discharge‐specific capacity of 1415 mAh g−1 at a high rate of 0.5 C. Additionally, the 2 Ah Li–S pouch cells deliver 315 Wh kg−1 and achieved 80% capacity retention after 50 cycles at 0.1 C with a high sulfur loading of 10 mg cm−2. Our study provides a practical method to introduce bifunctional electrocatalysts for boosting the electrochemical properties of Li–S batteries. [ABSTRACT FROM AUTHOR]

Author(s): Qi Feng [1, 2]; Yujun Zhang [1, 2]; Pei Hao [1, 2]; Shengyue Wang [2, 3]; Gang Fu [3]; Yucheng Huang [1]; Ying Li [1]; Jingjie Zhu [1]; Yilei [...]

A NiS2-modified sulfurized polyacrylonitrile composite is prepared by simply co-heating a mixture of sulfur, NiCO3, and polyacrylonitrile. The NiS2–SPAN cathode exhibits superior electrochemical performance, delivering a high reversible capacity of 1533 mA h gsulfur−1 (705 mA h gcomposite−1) at 0.2 A g−1 after 100 cycles and good rate capability (1180 mA h gsulfur−1 at 2 A g−1). [ABSTRACT FROM AUTHOR]

Although high energy lithium sulfur (Li–S) battery technology has been vigorously revisited in recent years, the practical application of Li–S batteries is still hindered due to the gap in scientific knowledge between fundamental research and the actual application need. Generally, the sulfur content and sulfur mass loading of sulfur electrodes along with the electrolyte/sulfur ratio are the crucial factors in achieving high-energy-density Li–S batteries. Here, we construct a micro–nano-structured CS@CTAB/ABS + CNTS electrode with a high sulfur content of 76 wt% and a high sulfur mass loading of 6.7–11.1 mg cm−2 for application in Li–S batteries via the blade-casting technique. Benefiting from the unique sulfur composite design, the thick sulfur electrodes demonstrated low polarization, high sulfur utilization and promising electrochemical stability. A high areal capacity of 6.0 mA h cm−2 over 50 cycles was achieved with a sulfur mass loading of 6.7 mg cm−2. And a higher areal capacity of 7.14 mA h cm−2 over 46 cycles could be achieved when the mass loading was increased to 8.9 mg cm−2. Even with a high sulfur mass loading of 11.1 mg cm−2, the sulfur electrode can still deliver a high areal capacity of 11.22 mA h cm−2 at a low electrolyte/sulfur ratio (4 : 1, μl : mg). Hence, this kind of sulfur composite would put forward the possibility of the practical utilization of high-energy-density Li–S batteries. [ABSTRACT FROM AUTHOR]

Rechargeable lithium–sulfur (Li–S) batteries are regarded as one of the most promising options for electrochemical energy storage systems owing to their high energy density and low cost. However, their practical use is hindered by multiple challenges and one of them is capacity decay caused by polysulfide dissolution and the insulating nature of sulfur. In this work, a core–shell structured composite (N-PCB/S) has been successfully prepared by depositing sulfur onto pigment carbon black (PCB) and grafting long chain quaternary ammonium ions via a facile method. These functional groups on the pigment carbon black can immobilize the inner layer of sulfur. And the grafted long chain quaternary ammonium ions could insert into the sulfur layer and anchor the outer layer polysulfides because of the electrostatic attraction between the quaternary ammonium cations and polysulfide anions. Therefore, the N-PCB/S composite electrode exhibits great improvement in both cycling performance and rate capability as compared to pristine sulfur and PCB/S composite electrodes, even when the sulfur content of the N-PCB/S composite is as high as 85%. At current densities of 0.1 and 1C, the N-PCB/S composite electrode delivered high reversible specific capacities of ∼1010 and 746 mA h g−1 after 100 cycles, respectively. [ABSTRACT FROM AUTHOR]

The lithium–sulfur (Li–S) battery is one of the most fascinating candidates for next-generation storage devices due to its remarkably high theoretical energy density of 2600 W h kg−1 and the low cost of the sulfur element. However, its actual application is still hindered by multiple challenges, such as the insulating nature of sulfur, irreversible loss of active material, and degradation of Li–metal anodes. In this paper, a functional sulfonated acetylene black (AB-SO3−) coated separator is designed to improve the overall performance of Li–S batteries. The AB-SO3− coated separator is highly permselective to lithium ions against polysulfide anions, while the incorporation of AB-SO3− coated separator does not influence the ion conductivity. Also the AB-SO3− coating could function as an upper current collector to facilitate electron transport for enhancing the electrochemical utilization of sulfur and ensuring the reactivation of the trapped active material. Therefore, the Li–S cell with the AB-SO3− coating exhibits significant improvement in both reversible capacity and cycling stability as compared to the cell with the pristine Celgard separator. When the mass of the AB-SO3− coating is counted into the whole mass of the sulfur cathode, the Li–S cell exhibits a high sulfur content of 70 wt% in the whole sulfur cathode region and 3.0 mg cm−2 sulfur mass loading. This kind of a cell delivers a high initial capacity of 1262 mA h g−1, and a superior capacity of 955 mA h g−1 was retained after 100 cycles at 0.1C. Consequently, the sulfonated carbon coated separator is promising for the construction of high performance batteries. [ABSTRACT FROM AUTHOR]

In this work, a novel Si/nitrogen-rich porous C composite was prepared by the simple co-assembly of gelatin, nano-CaCO3 particles and Si nanoparticles, followed by a pyrolysis process and a subsequent acid washing treatment to remove the template. The Si nanoparticles adhered to the nitrogen-rich porous carbon framework, which possesses good conductivity and adequate free space to accommodate the volume change of Si nanoparticles during cycling. In contrast with the bare Si nanoparticles and the conventional Si/C composite, the electrochemical performance of the as-prepared Si/nitrogen-rich porous C composite has been improved significantly. It delivers a reversible capacity of 1103 mA h g−1 after 100 cycles at a current density of 100 mA g−1 and 766 mA h g−1 at 2 A g−1, much higher than those of commercial graphite anodes. In addition, the synthesis method can be easily scaled up and widely applied to other high-capacity anode and cathode material systems that undergo large volume expansion. [ABSTRACT FROM AUTHOR]

Garnet-type Li 5 La 3 Ta 2 O 12 (LLTaO) solid electrolyte is a potential candidate component for future all-solid-state batteries due to its extraordinary stability against the reaction with molten lithium. In contrast with traditional cold isostatic pressing (CIP) method, which generally pursues ultra-high pressure, this paper tries to enhance the density and ionic conductivity of LLTaO by self-consolidation strategy without the assistance of any pressing operations. A LLTaO bulk with a relative density of 95% is obtained. SEM images reveal that the bulk sample is assembled by large dense particles in size of tens of microns indicating that the interstitial space among the particles has been dramatically minimized. Accordingly, the total ionic conductivity and the bulk ionic conductivity at 30 °C are promoted up about one order of magnitude higher to 2.63 × 10 −5 S cm −1 and 1.41 × 10 −4 S cm −1 , respectively. Moreover, the lithium ionic migration network in the crystalline unit cell of LLTaO is first explored from its assembled way. A hexagon-like basic unit with tetrahedral Li1 joint sites and Li1- - Li1 edges is identified. The tetrahedral Li1 sites act as crucial junctions for the transportation of lithium ions. This work would significantly stimulate the development of LLTaO electrolyte membrane technology. [ABSTRACT FROM AUTHOR]

It is still a considerable challenge for spinel Li 4 Ti 5 O 12 to achieve high tap density while retaining excellent power capability. Herein, a compact and mesopore-oriented holey-graphene framework (HGF) caging nano-Li 4 Ti 5 O 12 particles (Li 4 Ti 5 O 12 /HGF) is synthesized by capillary shrink effect. In the capillary drying process, nano-Li 4 Ti 5 O 12 particles prevent the absolute aggregation of graphene sheets, remaining mesopore-oriented porosity for rapid Li+ diffusion. After precisely adjusting the porous structure, Li 4 Ti 5 O 12 /HGF composite successfully achieves a balance between tap density and porosity. Furthermore, the in-plane nanopores of holey-graphene sheets provide channels for Li+ diffusion, obviously weakening the Li+ diffusion resistances of compact composite. The resultant Li 4 Ti 5 O 12 /HGF composite combines a high tap density of 1.1 g cm−3 and a moderate mesopore-oriented porosity with BET specific area of 152 m2 g−1, delivering volumetric-specific capacities of 161, 142, 120, 103 mA h cm−3 at 0.035, 1.75, 7 and 14 A g−1, respectively. Even as current density reaches 17.5 A g−1, the as-prepared Li 4 Ti 5 O 12 /HGF composite still displays a capacity of 98 mA h cm−3, showing excellent ultrahigh-rate performance. After 1000 cycles at 7A g−1, the capacity of dense Li 4 Ti 5 O 12 /HGF composite remains 84%, demonstrating high cycle stability. Image 1 • A balance between high tap density and mesopore-oriented structure. • Decreasing Li+ diffusion resistance due to holey-graphene sheets. • Excellent power capability and high cycle stability. [ABSTRACT FROM AUTHOR]