3D Printing Sulfur Copolymer‐Graphene Architectures for Li‐S Batteries

3D printing is becoming an efficient approach to facilely and accurately fabricate diverse complex architectures with broad applications. However, suitable inks and 3D print favorable architectures with high electrochemical performances for energy storage are still being explored. Here, sulfur copolymer‐graphene architectures with well‐designed periodic microlattices are 3D printed as a cathode for Li‐S batteries using a suitable ink composed of sulfur particles, 1,3‐diisopropenylbenzene (DIB), and condensed graphene oxide dispersion. Using thermal treatment, elemental sulfur can be reacted with DIB to produce sulfur copolymer, which can partially suppress the dissolution of polysulfides. Moreover, graphene in the architecture can provide high electrical conductivity for whole electrode. Hence, 3D printed sulfur copolymer‐graphene architecture exhibits a high reversible capacity of 812.8 mA h g^?1 and good cycle performance. Such a simple 3D printing approach can be further extended to construct many complex architectures for various energy storage devices.     

3D Hyperbranched Hollow Carbon Nanorod Architectures for High‐Performance Lithium‐Sulfur Batteries

Lithium‐sulfur batteries have been plagued for a long time by low Coulombic efficiency, fast capacity loss, and poor high rate performance. Here, the synthesis of 3D hyperbranched hollow carbon nanorod encapsulated sulfur nanocomposites as cathode materials for lithium‐sulfur batteries is reported. The sulfur nanocomposite cathodes deliver a high specific capacity of 1378 mAh g^‐1 at a 0.1C current rate and exhibit stable cycling performance. The as‐prepared sulfur nanocomposites also achieve excellent high rate capacities and cyclability, such as 990 mAh g^‐1 at 1C, 861 mAh g^‐1 at 5C, and 663 mAh g^‐1 at 10C, extending to more than 500 cycles. The superior electrochemical performance are ascribed to the unique 3D hyperbranched hollow carbon nanorod architectures and high length/radius aspect ratio of the carbon nanorods, which can effectively prevent the dissolution of polysulfides, decrease self‐discharge, and confine the volume expansion on cycling. High capacity, excellent high‐rate performance, and long cycle life render the as‐developed sulfur/carbon nanorod nanocomposites a promising cathode material for lithium‐sulfur batteries.     

3D Vertically Aligned and Interconnected Porous Carbon Nanosheets as Sulfur Immobilizers for High Performance Lithium‐Sulfur Batteries

A unique nanostructure of 3D and vertically aligned and interconnected porous carbon nanosheets (3D‐VCNs) is demonstrated by a simple carbonization of agar. The key feature of 3D‐VCNs is that they possess numerous 3D channels with macrovoids and mesopores, leading to high surface area of 1750 m² g^?1, which play an important role in loading large amount of sulfur, while vertically aligned microporous carbon nanosheets act as the multilayered physical barrier against polysulfides anions and prevent their dissolution in the electrolyte due to strong adsorption during cycling process. As a result, the 3D hybrid (3D‐S‐VCNs) infiltered with 68.3 wt% sulfur exhibits a high and stable reversible capacity of 844 mAh g^?1 at the current density of 837 mA g^?1 with excellent Coulombic efficiency ≈100%, capacity retention of ≈80.3% over 300 cycles, and good rate ability (the reversible capacity of 738 mAh g^?1 at the high current density of 3340 mA g^?1). The present work highlights the vital role of the introduction of 3D carbon nanosheets with macrovoids and mesopores in enhancing the performance of LSBs.     

3D,Mutually Embedded MOF@Carbon Nanotube Hybrid Networks for High‐Performance Lithium‐Sulfur Batteries

Metal‐organic frameworks (MOFs) hybridized with a conductive matrix could potentially serve as a sulfur host for lithium‐sulfur (Li‐S) battery electrodes; so far most of the previously studied hybrid structures are in the powder form or thin compact films. This study reports 3D porous MOF@carbon nanotube (CNT) networks by grafting MOFs with tailored particle size uniformly throughout a CNT sponge skeleton. Growing larger‐size MOF particles to entrap the conductive CNT network yields a mutually embedded structure with high stability, and after sulfur encapsulation, it shows an initial discharge capacity of ≈1380 mA h g^?1 (at 0.1 C) and excellent cycling stability with a very low fading rate. Furthermore, owing to the 3D porous network that is suitable for enhanced sulfur loading, a remarkable areal capacity of ≈11 mA h cm^?2 (at 0.1 C) is obtained, which is much higher than other MOF‐based hybrid electrodes. The mutually embedded MOF@CNTs with simultaneously high specific capacity, areal capacity, and cycling stability represent an advanced candidate for developing high‐performance Li‐S batteries and other energy storage systems.     

High Capacity All‐Solid‐State Lithium Batteries Enabled by Pyrite‐Sulfur Composites

As the theoretical limit of intercalation material‐based lithium‐ion batteries is approached, alternative chemistries based on conversion reactions are presently considered. The conversion of sulfur is particularly appealing as it is associated with a theoretical gravimetric energy density up to 2510 Wh kg^?1. In this paper, three different carbon‐iron disulfide‐sulfur (C‐FeS₂‐S) composites are proposed as alternative positive electrode materials for all‐solid‐state lithium‐sulfur batteries. These are synthesized through a facile, low‐cost, single‐step ball‐milling procedure. It is found that the crystalline structure (evaluated by X‐ray diffraction) and the morphology of the composites (evaluated by scanning electron microscopy) are greatly influenced by the FeS₂:S ratio. Li/LiI‐Li₃PS₄/C‐FeS₂‐S solid‐state cells are tested under galvanostatic conditions, while differential capacity plots are used to discuss the peculiar electrochemical features of these novel materials. These cells deliver capacities as high as 1200 mAh g_(FeS2+S)^?1 at the intermediate loading of 1 mg cm^?2 (1.2 mAh cm^?2), and up to 3.55 mAh cm^?2 for active material loadings as high as 5 mg cm^?2 at 20 °C. Such an excellent performance, rarely reported for (sulfur/metal sulfide)‐based, all solid‐state cells, makes these composites highly promising for real application where high positive electrode loadings are required.     

High‐Performance Lithium‐Sulfur Batteries with a Self‐Supported, 3D Li2S‐Doped Graphene Aerogel Cathodes

Lithium‐sulfur (Li‐S) batteries are being considered as the next‐generation high‐energy‐storage system due to their high theoretical energy density. However, the use of a lithium‐metal anode poses serious safety concerns due to lithium dendrite formation, which causes short‐circuiting, and possible explosions of the cell. One feasible way to address this issue is to pair a fully lithiated lithium sulfide (Li₂S) cathode with lithium metal‐free anodes. However, bulk Li₂S particles face the challenges of having a large activation barrier during the initial charge, low active‐material utilization, poor electrical conductivity, and fast capacity fade, preventing their practical utility. Here, the development of a self‐supported, high capacity, long‐life cathode material is presented for Li‐S batteries by coating Li₂S onto doped graphene aerogels via a simple liquid infiltration–evaporation coating method. The resultant cathodes are able to lower the initial charge voltage barrier and attain a high specific capacity, good rate capability, and excellent cycling stability. The improved performance can be attributed to the (i) cross‐linked, porous graphene network enabling fast electron/ion transfer, (ii) coated Li₂S on graphene with high utilization and a reduced energy barrier, and (iii) doped heteroatoms with a strong binding affinity toward Li₂S/lithium polysulfides with reduced polysulfide dissolution based on first‐principles calculations.     

Ultrafine Co3Se4 Nanoparticles in Nitrogen‐Doped 3D Carbon Matrix for High‐Stable and Long‐Cycle‐Life Lithium Sulfur Batteries

Lithium–sulfur batteries are a promising high energy output solution for substitution of traditional lithium ion batteries. In recent times research in this field has stepped into the exploration of practical applications. However, their applications are impeded by cycling stability and short life‐span mainly due to the notorious polysulfide shuttle effect. In this work, a multifunctional sulfur host fabricated by grafting highly conductive Co₃Se₄ nanoparticles onto the surface of an N‐doped 3D carbon matrix to inhibit the polysulfide shuttle and improve the sulfur utilization is proposed. By regulating the carbon matrix and the Co₃Se₄ distribution, N‐CN‐750@Co₃Se₄‐0.1 m with abundant polar sites is experimentally and theoretically shown to be a good LiPSs absorbent and a sulfur conversion accelerator. The S/N‐CN‐750@Co₃Se₄‐0.1 m cathode shows excellent sulfur utilization, rate performance, and cyclic durability. A prolonged cycling test of the as‐fabricated S/N‐CN‐750@Co₃Se₄‐0.1 m cathode is carried out at 0.2 C for more than 5 months which delivers a high initial capacity of 1150.3 mAh g^?1 and retains 531.0 mAh g^?1 after 800 cycles with an ultralow capacity reduction of 0.067% per cycle, maintaining Coulombic efficiency of more than 99.3%. The reaction details are characterized and analyzed by ex situ measurements. This work highly emphasizes the potential capabilities of transition‐metal selenides in lithium–sulfur batteries.     

Flexible and High‐Loading Lithium–Sulfur Batteries Enabled by Integrated Three‐In‐One Fibrous Membranes

Lithium–sulfur batteries are appealing as high‐energy storage systems and hold great application prospects in wearable and portable electronics. However, severe shuttle effects, low sulfur conductivity, and especially poor electrode mechanical flexibility restrict sulfur utilization and loading for practical applications. Herein, high‐flux, flexible, electrospun fibrous membranes are developed, which succeed in integrating three functional units (cathode, interlayer, and separator) into an efficient composite. This structure helps to eliminate negative interface effects, and effectively drives synergistic boosts to polysulfide confinement, electron transfer, and lithium‐ion diffusion. It delivers a high initial capacity of 1501 mA h g^?1 and a discharge capacity of 933 mA h g^?1 after 400 cycles, with slow capacity attenuation (0.069% per cycle). Even under high sulfur loading (13.2 mg cm^?2, electrolyte/sulfur ratio = 6 mL g^?1) or in an alternative folded state, this three‐in‐one membrane still exhibits high areal capacity (11.4 mA h cm^?2) and exceptional application performance (powering an array of over 30 light‐emitting diodes (LEDs)), highlighting its huge potential in high‐energy flexible devices.     

Performance Improvement of Magnesium Sulfur Batteries with Modified Non‐Nucleophilic Electrolytes

The combination of a magnesium anode with a sulfur cathode is one of the most promising electrochemical couples because of its advantages of good safety, low cost, and a high theoretical energy density. However, magnesium sulfur batteries are still in a very early stage of research and development, and the discovery of suitable electrolytes is the key challenge for further improvement. Here, a new preparation method for non‐nucleophilic electrolyte solutions using a two‐step reaction in one‐pot is presented, which provides a feasible way to optimize the physiochemical properties of the electrolyte for the application in magnesium sulfur batteries. The first use of modified electrolytes in glymes and binary solvents of glyme and ionic liquid shows beneficial effects on the performance of magnesium sulfur batteries. New insights into the reaction mechanism of electrochemical conversion between magnesium and sulfur are also investigated.     

Silica Restricting the Sulfur Volatilization of Nickel Sulfide for High‐Performance Lithium‐Ion Batteries

Nickel sulfides are regarded as promising anode materials for advanced rechargeable lithium‐ion batteries due to their high theoretical capacity. However, capacity fade arising from significant volume changes during operation greatly limits their practical applications. Herein, confined NiS_x@C yolk–shell microboxes are constructed to address volume changes and confine the active material in the internal void space. Having benefited from the yolk–shell structure design, the prepared NiS_x@C yolk–shell microboxes display excellent electrochemical performance in lithium‐ion batteries. Particularly, it delivers impressive cycle stability (460 mAh g^?1 after 2000 cycles at 1 A g^?1) and superior rate performance (225 mAh g^?1 at 20 A g^?1). Furthermore, the lithium storage mechanism is ascertained with in situ synchrotron high‐energy X‐ray diffractions and in situ electrochemical impedance spectra. This unique confined yolk–shell structure may open up new strategies to create other advanced electrode materials for high performance electrochemical storage systems.