Freestanding Bilayer Carbon–Sulfur Cathode with Function of Entrapping Polysulfide for High Performance Li–S Batteries

Li–S batteries benefit from numerous advantages such as high theoretical capacity, high energy density, and availability of an abundance of sulfur. However, commercialization of Li–S batteries has been impeded because of low loading amount of active materials and poor cycle performance. Herein, a freestanding bilayer carbon–sulfur (FBCS) cathode is reported with superior electrochemical performance at a high sulfur loading level (3 mg cm^?2). The top component of the FBCS cathode is composed of interlacing multiwalled carbon nanotubes (MWCNT) and the bottom component is made up of a mixed layer of sulfur imbedded in MWCNT and N‐doped porous carbon (NPC). The MWCNT layer (top part of FBCS cathode) blocks polysulfide migration from the cathode to the anode, and NPC in the bottom part of the FBCS cathode not only provides spacious active sites but also absorbs polysulfide by the nitrogen functional group. The designed novel FBCS cathode delivered a high initial discharge capacity of 964 and 900 mAh g^?1 at 0.5 and 1 C, respectively. It also displayed an excellent capacity retention of 83.1% at 0.5 C and 83.4% at 1 C after 300 cycles.     

Confined Sulfur in Microporous Carbon Renders Superior Cycling Stability in Li/S Batteries

The use of sulfur in the next generation Li‐ion batteries is currently precluded by its poor cycling stability caused by irreversible Li₂S formation and the dissolution of soluble polysulfides in organic electrolytes that leads to parasitic cell reactions. Here, a new C/S cathode material comprising short‐chain sulfur species (predominately S₂) confined in carbonaceous subnanometer and the unique charge mechanism for the subnano‐entrapped S₂ cathodes are reported. The first charge–discharge cycle of the C/S cathode in the carbonate electrolyte forms a new type of thiocarbonate‐like solid electrolyte interphase (SEI). The SEI coated C/S cathode stably delivers ≈600 mAh g^?1 capacity over 4020 cycles (0.0014% loss cycle^?1) at ≈100% Coulombic efficiency. Extensive X‐ray photoelectron spectroscopy analysis of the discharged cathodes shows a new type of S₂ species and a new carbide‐like species simultaneously, and both peaks disappear upon charging. These data suggest a new sulfur redox mechanism involving a separated Li⁺/S^2? ion couple that precludes Li₂S compound formation and prevents the dissolution of soluble sulfur anions. This new charge/discharge process leads to remarkable cycling stability and reversibility.     

3D Interconnected Porous Carbon Aerogels as Sulfur Immobilizers for Sulfur Impregnation for Lithium‐Sulfur Batteries with High Rate Capability and Cycling Stability

To eliminate capacity‐fading effects due to the loss of sulfur cathode materials as a result of polysulfide dissolution in lithium–sulfur (Li–S) cells, 3D carbon aerogel (CA) materials with abundant narrow micropores can be utilized as an immobilizer host for sulfur impregnation. The effects of S incorporation on microstructure, surface area, pore size distribution, and pore volume of the S/CA hybrids are studied. The electrochemical performance of the S/CA hybrids is investigated using electrochemical impedance spectroscopy, galvanostatical charge–discharge, and cyclic voltammetry techniques. The 3D porous S/CA hybrids exhibit significantly improved reversible capacity, high‐rate capability, and excellent cycling performance as a cathode electrode for Li–S batteries. The S/CA hybrid with an optimal incorporating content of 27% S shows an excellent reversible capacity of 820 mAhg^?1 after 50 cycles at a current density of 100 mAg^?1. Even at a current density of 3.2C (5280 mAg^?1), the reversible capacity of 27%S/CA hybrid can still maintain at 521 mAhg^?1 after 50 cycles. This strategy for the S/CA hybrids as cathode materials to utilize the abundant micropores for sulfur immobilizers for sulfur impregnation for Li–S battery offers a new way to solve the long‐term reversibility obstacle and provides guidelines for designing cathode electrode architectures.     

Functional Mesoporous Carbon‐Coated Separator for Long‐Life,High‐Energy Lithium–Sulfur Batteries

The lithium–sulfur (Li–S) battery is regarded as the most promising rechargeable energy storage technology for the increasing applications of clean energy transportation systems due to its remarkable high theoretical energy density of 2.6 kWh kg^?1, considerably outperforming today's lithium‐ion batteries. Additionally, the use of sulfur as active cathode material has the advantages of being inexpensive, environmentally benign, and naturally abundant. However, the insulating nature of sulfur, the fast capacity fading, and the short lifespan of Li–S batteries have been hampered their commercialization. In this paper, a functional mesoporous carbon‐coated separator is presented for improving the overall performance of Li–S batteries. A straightforward coating modification of the commercial polypropylene separator allows the integration of a conductive mesoporous carbon layer which offers a physical place to localize dissolved polysulfide intermediates and retain them as active material within the cathode side. Despite the use of a simple sulfur–carbon black mixture as cathode, the Li–S cell with a mesoporous carbon‐coated separator offers outstanding performance with an initial capacity of 1378 mAh g^?1 at 0.2 C, and high reversible capacity of 723 mAh g^?1, and degradation rate of only 0.081% per cycle, after 500 cycles at 0.5 C.     

Manipulating Polysulfide Conversion with Strongly Coupled Fe3O4 and Nitrogen Doped Carbon for Stable and High Capacity Lithium–Sulfur Batteries

Li–S batteries are among the most promising energy storage technologies but their commercialization faces substantial challenges, largely due to difficulties in controlling their reaction pathways under practical conditions. Here, the synthesis of strongly coupled Fe₃O₄ and N‐doped carbon directly in flexible carbon cloth is demonstrated, as well as their novel use for hosting sulfur with outstanding performance for Li–S batteries. It is discovered that the synergistic effects of Fe₃O₄ and N‐carbon bring strong adsorption toward lithium polysulfide, and ensure nearly complete conversion of short‐chain polysulfide to Li₂S during discharge. The Li₂S solids generated on these novel hosts are extremely reactive and can be readily charged back to S without a noticeable overpotential. The critical roles of Fe₃O₄ and N‐doped carbon are studied and direct correlations are established between their surface concentration/crystallinity and the Li₂S₄ to Li₂S conversion capacity. This novel manipulation of polysulfide conversion allows to fabricate freestanding and flexible sulfur cathodes that deliver a specific capacity of 1316 mAh g^?1 at 0.1C and stable cycling for 1000 cycles at 0.2C under a high sulfur loading of ≈4.7 mg cm^?2.     

Ferromagnetic Nanoparticle–Assisted Polysulfide Trapping for Enhanced Lithium–Sulfur Batteries

The lithium–sulfur (Li–S) battery is a promising candidate for next‐generation high‐density energy storage devices because of its ultrahigh theoretical energy density and the natural abundance of sulfur. However, the practical performance of the sulfur cathode is plagued by fast capacity decay and poor cycle life, both of which can be attributed to the intrinsic dissolution/shuttling of lithium polysulfides. Here, a new built‐in magnetic field–enhanced polysulfide trapping mechanism is discovered by introducing ferromagnetic iron/iron carbide (Fe/Fe₃C) nanoparticles with a graphene shell (Fe/Fe₃C/graphene) onto a flexible activated cotton textile (ACT) fiber to prepare the ACT@Fe/Fe₃C/graphene sulfur host. The novel trapping mechanism is demonstrated by significant differences in the diffusion behavior of polysulfides in a custom‐designed liquid cell compared to a pure ACT/S cathode. Furthermore, a cell assembled using the ACT@Fe/Fe₃C/S cathode exhibits a high initial discharge capacity of ≈764 mAh g^?1, excellent rate performance, and a remarkably long lifespan of 600 cycles using ACT@Fe/Fe₃C/S (whereas only 100 cycles can be achieved using pure ACT/S). The new magnetic field–enhanced trapping mechanism provides not only novel insight but unveils new possibilities for mitigating the “shuttle effect” of polysulfides thereby promoting the practical applications of Li–S batteries.     

Effective Polysulfide Rejection by Dipole‐Aligned BaTiO3 Coated Separator in Lithium–Sulfur Batteries

Although the exceptional theoretical specific capacity (1672 mAh g^?1) of elemental sulfur makes lithium–sulfur (Li–S) batteries attractive for upcoming rechargeable battery applications (e.g., electrical vehicles, drones, unmanned aerial vehicles, etc.), insufficient cycle lives of Li–S cells leave a substantial gap before their wide penetration into commercial markets. Among the key features that affect the cyclability, the shuttling process involving polysulfides (PS) dissolution is most fatal. In an effort to suppress this chronic PS shuttling, herein, a separator coated with poled BaTiO₃ or BTO particles is introduced. Permanent dipoles that are formed in the BTO particles upon the application of an electric field can effectively reject PS from passing through the separator via electrostatic repulsion, resulting in significantly improved cyclability, even when a simple mixture of elemental sulfur and conductive carbon is used as a sulfur cathode. The coating of BTO particles also considerably suppresses thermal shrinkage of the poly(ethylene) separator at high temperatures and thus enhances the safety of the cell adopting the given separator. The incorporation of poled particles can be universally applied to a wide range of rechargeable batteries (i.e., metal‐air batteries) that suffer from cross‐contamination of charged species between both electrodes.     

Lithium Tritelluride as an Electrolyte Additive for Stabilizing Lithium Deposition and Enhancing Sulfur Utilization in Anode-Free Lithium–Sulfur Batteries

Despite the potential to become the next-generation energy storage technology, practical lithium–sulfur (Li–S) batteries are still plagued by the poor cyclability of the lithium-metal anode and sluggish conversion kinetics of S species. In this study, lithium tritelluride (LiTe₃), synthesized with a simple one-step process, is introduced as a novel electrolyte additive for Li–S batteries. LiTe₃ quickly reacts with lithium polysulfides and functions as a redox mediator to greatly improve the cathode kinetics and the utilization of active materials in the cathode. Moreover, the formation of a Li₂TeS₃/Li₂Te-enriched interphase layer on the anode surface enhances ionic transport and stabilizes Li deposition. By regulating the chemistry on both the anode and cathode sides, this additive enables a stable operation of anode-free Li–S batteries with only 0.1 m concentration in conventional ether-based electrolytes. The cell with the LiTe₃ additive retains 71% of the initial capacity after 100 cycles, while the control cell retains only 23%. More importantly, with high utilization of Te, the additive enables significantly better cyclability of anode-free pouch full-cells under lean electrolyte conditions.     

Hierarchical Free‐Standing Carbon‐Nanotube Paper Electrodes with Ultrahigh Sulfur‐Loading for Lithium–Sulfur Batteries

The rational combination of conductive nanocarbon with sulfur leads to the formation of composite cathodes that can take full advantage of each building block; this is an effective way to construct cathode materials for lithium–sulfur (Li–S) batteries with high energy density. Generally, the areal sulfur‐loading amount is less than 2.0 mg cm^?2, resulting in a low areal capacity far below the acceptable value for practical applications. In this contribution, a hierarchical free‐standing carbon nanotube (CNT)‐S paper electrode with an ultrahigh sulfur‐loading of 6.3 mg cm^?2 is fabricated using a facile bottom–up strategy. In the CNT–S paper electrode, short multi‐walled CNTs are employed as the short‐range electrical conductive framework for sulfur accommodation, while the super‐long CNTs serve as both the long‐range conductive network and the intercrossed mechanical scaffold. An initial discharge capacity of 6.2 mA·h cm^?2 (995 mA·h g^?1), a 60% utilization of sulfur, and a slow cyclic fading rate of 0.20%/cycle within the initial 150 cycles at a low current density of 0.05 C are achieved. The areal capacity can be further increased to 15.1 mA·h cm^?2 by stacking three CNT–S paper electrodes—resulting in an areal sulfur‐loading of 17.3 mg cm^?2—for the cathode of a Li–S cell. The as‐obtained free‐standing paper electrode are of low cost and provide high energy density, making them promising for flexible electronic devices based on Li–S batteries.     

Nitrogen‐Doped Mesoporous Carbon Promoted Chemical Adsorption of Sulfur and Fabrication of High‐Areal‐Capacity Sulfur Cathode with Exceptional Cycling Stability for Lithium‐Sulfur Batteries

As one important component of sulfur cathodes, the carbon host plays a key role in the electrochemical performance of lithium‐sulfur (Li‐S) batteries. In this paper, a mesoporous nitrogen‐doped carbon (MPNC)‐sulfur nanocomposite is reported as a novel cathode for advanced Li‐S batteries. The nitrogen doping in the MPNC material can effectively promote chemical adsorption between sulfur atoms and oxygen functional groups on the carbon, as verified by X‐ray absorption near edge structure spectroscopy, and the mechanism by which nitrogen enables the behavior is further revealed by density functional theory calculations. Based on the advantages of the porous structure and nitrogen doping, the MPNC‐sulfur cathodes show excellent cycling stability (95% retention within 100 cycles) at a high current density of 0.7 mAh cm^‐2 with a high sulfur loading (4.2 mg S cm^‐2) and a sulfur content (70 wt%). A high areal capacity (≈3.3 mAh cm^‐2) is demonstrated by using the novel cathode, which is crucial for the practical application of Li‐S batteries. It is believed that the important role of nitrogen doping promoted chemical adsorption can be extended for development of other high performance carbon‐sulfur composite cathodes for Li‐S batteries.     

A Lithium‐Sulfur Battery with a High Areal Energy Density

The battery community has recently witnessed a considerable progress in the cycle lives of lithium‐sulfur (Li‐S) batteries, mostly by developing the electrode structures that mitigate fatal dissolution of lithium polysulfides. Nonetheless, most of the previous successful demonstrations have been based on limited areal capacities. For realistic battery applications, however, the chronic issues from both the anode (lithium dendrite growth) and the cathode (lithium polysulfide dissolution) need to be readdressed under much higher loading of sulfur active material. To this end, the current study integrates the following three approaches in a systematic manner: 1) the sulfur electrode material with diminished lithium polysulfide dissolution by the covalently bonded sulfur‐carbon microstructure, 2) mussel‐inspired polydopamine coating onto the separator that suppresses lithium dendrite growth by wet‐adhesion between the separator and Li metal, and 3) addition of cesium ions (Cs⁺) to the electrolyte to repel incoming Li ions and thus prevent Li dendrite growth. This combined strategy resolves the long‐standing problems from both electrodes even under the very large sulfur‐carbon composite loading of 17 mg cm^?2 in the sulfur electrode, enabling the highest areal capacity (9 mAh cm^?2) to date while preserving stable cycling performance.     

Designing a High‐Performance Lithium–Sulfur Batteries Based on Layered Double Hydroxides–Carbon Nanotubes Composite Cathode and a Dual‐Functional Graphene–Polypropylene–Al2O3 Separator

Designing an optimum cell configuration that can deliver high capacity, fast charge–discharge capability, and good cycle retention is imperative for developing a high‐performance lithium–sulfur battery. Herein, a novel lithium–sulfur cell design is proposed, which consists of sulfur and magnesium–aluminum‐layered double hydroxides (MgAl‐LDH)–carbon nanotubes (CNTs) composite cathode with a modified polymer separator produced by dual side coating approaches (one side: graphene and the other side: aluminum oxides). The composite cathode functions as a combined electrocatalyst and polysulfide scavenger, greatly improving the reaction kinetics and stabilizing the Coulombic efficiency upon cycling. The modified separator enhances further Li⁺‐ion or electron transport and prevents undesirable contact between the cathode and dendritic lithium on the anode. The proposed lithium–sulfur cell fabricated with the as‐prepared composite cathode and modified separator exhibits a high initial discharge capacity of 1375 mA h g^?1 at 0.1 C rate, excellent cycling stability during 200 cycles at 1 C rate, and superior rate capability up to 5 C rate, even with high sulfur loading of 4.0 mg cm^?2. In addition, the findings that found in postmortem chracterization of cathode, separator, and Li metal anode from cycled cell help in identifying the reason for its subsequent degradation upon cycling in Li–S cells.     

Lithium–Magnesium Alloy as a Stable Anode for Lithium–Sulfur Battery

Lithium–sulfur (Li–S) batteries are regarded as the promising next‐generation energy storage device due to the high theoretical energy density and low cost. However, the practical application of Li–S batteries is still limited owing to the cycle stability of both the sulfur cathode and lithium anode. In particular, the instability in the bulk and at the surface of the lithium anode during cycling becomes a huge obstacle for the practical application of Li–S battery. Herein, a Li‐rich lithium–magnesium (Li–Mg) alloy is investigated as an anode for Li–S batteries, based on the consideration of improving the stability in the bulk and at the surface of the lithium anode. Our experimental results reveal that the robust passivation layer is formed on the surface of the Li–Mg alloy anode, which is helpful to reduce side reactions, and enable the smooth surface morphology of anode during cycling. Meanwhile, the mixed electron and Li‐ion conducting matrix of the Li‐poor Li–Mg alloy as a porous skeleton structure can also be formed after delithiation, which can guarantee the structural integrity of the anode in the bulk during Li stripping/plating process. Therefore, the Li‐rich Li–Mg alloy is demonstrated to be a very promising anode material for Li–S battery.     

A Flexible 3D Multifunctional MgO‐Decorated Carbon Foam@CNTs Hybrid as Self‐Supported Cathode for High‐Performance Lithium‐Sulfur Batteries

One of the critical challenges to develop advanced lithium‐sulfur (Li‐S) batteries lies in exploring a high efficient stable sulfur cathode with robust conductive framework and high sulfur loading. Herein, a 3D flexible multifunctional hybrid is rationally constructed consisting of nitrogen‐doped carbon foam@CNTs decorated with ultrafine MgO nanoparticles for the use as advanced current collector. The dense carbon nanotubes uniformly wrapped on the carbon foam skeletons enhance the flexibility and build an interconnected conductive network for rapid ionic/electronic transport. In particular, a synergistic action of MgO nanoparticles and in situ N‐doping significantly suppresses the shuttling effect via enhanced chemisorption of lithium polysulfides. Owing to these merits, the as‐built electrode with an ultrahigh sulfur loading of 14.4 mg cm^?2 manifests a high initial areal capacity of 10.4 mAh cm^?2, still retains 8.8 mAh cm^?2 (612 mAh g^?1 in gravimetric capacity) over 50 cycles. The best cycling performance is achieved upon 800 cycles with an extremely low decay rate of 0.06% at 2 C. Furthermore, a flexible soft‐packaged Li‐S battery is readily assembled, which highlights stable electrochemical characteristics under bending and even folding. This cathode structural design may open up a potential avenue for practical application of high‐sulfur‐loading Li‐S batteries toward flexible energy‐storage devices.     

Status and Prospects of MXene-Based Lithium–Sulfur Batteries

Lithium–sulfur (Li–S) batteries with a theoretical energy density of 2567 Wh kg⁻¹ are very promising next-generation energy storage systems, but suffer from the insulativity of sulfur and Li₂S, the shuttle effect due to the dissolution and migration of polysulfides, and the lithium dendrite issue. MXenes, a family of 2D transition metal carbides/nitrides, which have metallic conductivity, structural variety, strong chemical adsorption ability to polysulfides, effective catalytic effect for fast kinetics, and inducing effect for uniform growth of Li, exhibit promising potential for high-performance Li–S batteries. In this review, the recent progress and achievements of MXene-based Li–S batteries are summarized, including the use of MXenes in sulfur cathode, interlayer between cathode and separator, and Li anode. The architecture construction and chemical modification of MXenes, as well as hybridization with other materials are demonstrated. The enhancement on electrochemical performance and the related mechanisms of MXenes and MXene-based composites are discussed. Finally, challenges and perspectives of MXenes for Li–S battery application are also given.     

Sulfurized Polyacrylonitrile Cathodes with High Compatibility in Both Ether and Carbonate Electrolytes for Ultrastable Lithium–Sulfur Batteries

Sulfurized polyacrylonitrile (SPAN) is a promising material capable of suppressing polysulfide dissolution in lithium–sulfur (Li–S) batteries with carbonate electrolyte. However, undesirable spontaneous formation of soluble polysulfides may arise in the ether electrolyte, and the conversion of sulfur in SPAN during the lithiation/delithiation processes is yet to be understood. Here, a highly reliable Li–S system using a freestanding fibrous SPAN cathode, as well as the sulfur conversion mechanism involved, is demonstrated. The SPAN shows high compatibility in both ether and carbonate electrolytes. The sulfur atoms existing in the form of short ? S₂? and ? S₃? chains are covalently bonded to the pyrolyzed PAN backbone. The electrochemical reduction of the SPAN by Li⁺ is a single‐phase solid–solid reaction with Li₂S as the sole discharge product. Meanwhile, the parasitic reaction between Li⁺ and C?N bonds exists upon the first discharge, and the residual Li⁺ enhances the conductivity of the backbone. The recharge ability and rate capability are kinetically dominated by the activation of Li₂S nanoflakes generated during discharge. At 800 mA g^?1, a specific capacity of 1180 mAh g^?1 is realized without capacity fading in the measured 1000 cycles, which makes SPAN promising for practical application.     

Conductive CoOOH as Carbon‐Free Sulfur Immobilizer to Fabricate Sulfur‐Based Composite for Lithium–Sulfur Battery

Lithium–sulfur battery is recognized as one of the most promising energy storage devices, while the application and commercialization are severely hindered by both the practical gravimetric and volumetric energy densities due to the low sulfur content and tap density with lightweight and nonpolar porous carbon materials as sulfur host. Herein, for the first time, conductive CoOOH sheets are introduced as carbon‐free sulfur immobilizer to fabricate sulfur‐based composite as cathode for lithium–sulfur battery. CoOOH sheet is not only a good sulfur‐loading matrix with high electron conductivity, but also exhibits outstanding electrocatalytic activity for the conversion of soluble lithium polysulfide. With an ultrahigh sulfur content of 91.8 wt% and a tap density of 1.26 g cm^?3, the sulfur/CoOOH composite delivers high gravimetric capacity and volumetric capacity of 1199.4 mAh g^?1_‐composite and 1511.3 mAh cm^?3 at 0.1C rate, respectively. Meanwhile, the sulfur‐based composite presents satisfactory cycle stability with a slow capacity decay rate of 0.09% per cycle within 500 cycles at 1C rate, thanks to the strong interaction between CoOOH and soluble polysulfides. This work provides a new strategy to realize the combination of gravimetric energy density, volumetric energy density, and good electrochemical performance of lithium–sulfur battery.     

All‐Purpose Electrode Design of Flexible Conductive Scaffold toward High‐Performance Li–S Batteries

The main obstacles that hinder the development of efficient lithium sulfur (Li–S) batteries are the polysulfide shuttling effect in sulfur cathode and the uncontrollable growth of dendritic Li in the anode. An all‐purpose flexible electrode that can be used both in sulfur cathode and Li metal anode is reported, and its application in wearable and portable storage electronic devices is demonstrated. The flexible electrode consists of a bimetallic CoNi nanoparticle‐embedded porous conductive scaffold with multiple Co/Ni‐N active sites (CoNi@PNCFs). Both experimental and theoretical analysis show that, when used as the cathode, the CoNi and Co/Ni‐N active sites implanted on the porous CoNi@PNCFs significantly promote chemical immobilization toward soluble lithium polysulfides and their rapid conversion into insoluble Li₂S, and therefore effectively mitigates the polysulfide shuttling effect. Additionally, a 3D matrix constructed with porous carbonous skeleton and multiple active centers successfully induces homogenous Li growth, realizing a dendrite‐free Li metal anode. A Li–S battery assembled with S/CoNi@PNCFs cathode and Li/CoNi@PNCFs anode exhibits a high reversible specific capacity of 785 mAh g^?1 and long cycle performance at 5 C (capacity fading rate of 0.016% over 1500 cycles).     

Accelerated Li+ Desolvation for Diffusion Booster Enabling Low-Temperature Sulfur Redox Kinetics via Electrocatalytic Carbon-Grazfted-CoP Porous Nanosheets

Lithium–sulfur (Li–S) batteries are famous for their high energy density and low cost, but prevented by sluggish redox kinetics of sulfur species due to depressive Li ion diffusion kinetics, especially under low-temperature environment. Herein, a combined strategy of electrocatalysis and pore sieving effect is put forward to dissociate the Li⁺ solvation structure to stimulate the free Li⁺ diffusion, further improving sulfur redox reaction kinetics. As a protocol, an electrocatalytic porous diffusion-boosted nitrogen-doped carbon-grafted-CoP nanosheet is designed via forming the N Co P active structure to release more free Li⁺ to react with sulfur species, as fully investigated by electrochemical tests, theoretical simulations and in situ/ex situ characterizations. As a result, the cells with diffusion booster achieve desirable lifespan of 800 cycles at 2 C and excellent rate capability (775 mAh g⁻¹ at 3 C). Impressively, in a condition of high mass loading or low-temperature environment, the cell with 5.7 mg cm⁻² stabilizes an areal capacity of 3.2 mAh cm⁻² and the charming capacity of 647 mAh g⁻¹ is obtained under 0 °C after 80 cycles, demonstrating a promising route of providing more free Li ions toward practical high-energy Li–S batteries.     

Carbonized‐MOF as a Sulfur Host for Aluminum–Sulfur Batteries with Enhanced Capacity and Cycling Life

The rechargeable aluminum–sulfur (Al–S) battery is a promising next generation electrochemical energy storage system owing to its high theoretical capacity of 1672 mAh g^?1 and in combining low‐cost and naturally abundant elements, Al and S. However, to date, its poor reversibility and low lifespan have limited its practical application. In this paper, a composite cathode is reported for Al–S batteries based on S anchored on a carbonized HKUST‐1 matrix (S@HKUST‐1‐C). The S@HKUST‐1‐C composite maintains a reversible capacity of 600 mAh g^?1 at the 75th cycle and a reversible capacity of 460 mAh g^?1 at the 500th cycle under a current density of 1 A g^?1, with a Coulombic efficiency of around 95%. X‐ray diffraction and Auger spectrum results reveal that the Cu in HKUST‐1 forms S–Cu ionic clusters. This serves to facilitate the electrochemical reaction and improve the reversibility of S during charge/discharge. Additionally, Cu increases the electron conductivity at the carbon matrix/S interface to significantly decrease the kinetic barrier for the conversion of sulfur species during battery operation.