Long-Life Lithium-Sulfur Batteries with a Bifunctional Cathode Substrate Configured with Boron Carbide Nanowires

Rational Design of Two-Dimensional MA2Z4 Monolayers as Effective Anchoring Materials for Lithium-Sulfur Batteries

Advances in lithium-sulfur batteries (LSBs) are impeded by the inefficiency of anchoring materials in facilitating long-term cycling and rate performance. To address this challenge, an exploration of two-dimensional MA2Z4 monolayers as potential anchoring materials for LSBs is proposed based on density functional theory calculations and machine learning (ML) techniques. Adsorption features, sulfur reduction reaction behaviors, and solvent interactions are assessed and analyzed; and MoGe2N4 and WGe2N4 are identified as the most promising candidates because they have optimal adsorption energies for lithium polysulfides to suppress the shuttle effect and exhibit enhanced catalytic activity. Meanwhile, ML analysis highlights the critical influence of the electronegativity of element Z in MA2Z4 on anchoring properties, providing valuable insights into future anchoring material design for high-performance LSBs.

Rechargeable Metal-Sulfur Batteries: Key Materials to Mechanisms

Rechargeable metal-sulfur batteries are considered promising candidates for energy storage due to their high energy density along with high natural abundance and low cost of raw materials. However, they could not yet be practically implemented due to several key challenges: (i) poor conductivity of sulfur and the discharge product metal sulfide, causing sluggish redox kinetics, (ii) polysulfide shuttling, and (iii) parasitic side reactions between the electrolyte and the metal anode. To overcome these obstacles, numerous strategies have been explored, including modifications to the cathode, anode, electrolyte, and binder. In this review, the fundamental principles and challenges of metal-sulfur batteries are first discussed. Second, the latest research on metal-sulfur batteries is presented and discussed, covering their material design, synthesis methods, and electrochemical performances. Third, emerging advanced characterization techniques that reveal the working mechanisms of metal-sulfur batteries are highlighted. Finally, the possible future research directions for the practical applications of metal-sulfur batteries are discussed. This comprehensive review aims to provide experimental strategies and theoretical guidance for designing and understanding the intricacies of metal-sulfur batteries; thus, it can illuminate promising pathways for progressing high-energy-density metal-sulfur battery systems.

Unraveling the Coupling Effect between Cathode and Anode toward Practical Lithium-Sulfur Batteries

The localized reaction heterogeneity of the sulfur cathode and the uneven Li deposition on the Li anode are intractable issues for lithium-sulfur (Li-S) batteries under practical operation. Despite impressive progress in separately optimizing the sulfur cathode or Li anode, a comprehensive understanding of the highly coupled relationship between the cathode and anode is still lacking. In this work, inspired by the Butler-Volmer equation, a binary descriptor (IBD ) assisting the rational structural design of sulfur cathode by simultaneously considering the mass-transport index (Imass ) and the charge-transfer index (Icharge ) is identified, and subsequently the relationship between IBD and the morphological evolution of Li anode is established. Guided by the IBD , a scalable electrode providing interpenetrated flow channels for efficient mass/charge transfer, full utilization of active sulfur, and mechanically elastic support for aggressive electrochemical reactions under practical conditions is reported. These characteristics induce a homogenous distribution of local current densities and reduced reaction heterogeneity on both sides of the cathode and anode. Impressive energy density of 318 Wh kg-1 and 473 Wh L-1 in an Ah-level pouch cell can be achieved by the design concept. This work offers a promising paradigm for unlocking the interaction between cathode and anode and designing high-energy practical Li-S batteries.

Transition Metal Phosphides: The Rising Star of Lithium-Sulfur Battery Cathode Host

Lithium-sulfur batteries (LSBs) with ultra-high energy density (2600 W h kg-1 ) and readily available raw materials are emerging as a potential alternative device with low cost for lithium-ion batteries. However, the insulation of sulfur and the unavoidable shuttle effect leads to slow reaction kinetics of LSBs, which in turn cause various roadblocks including poor rate capability, inferior cycling stability, and low coulombic efficiency. The most effective way to solve the issues mentioned above is to rationally design and control the synthesis of the cathode host for LSBs. Transition metal phosphides (TMPs) with good electrical conductivity and dual adsorption-conversion capabilities for polysulfide (PS) are regarded as promising cathode hosts for new-generation LSBs. In this review, the main obstacles to commercializing the LSBs and the development processes of their cathode host are first elaborated. Then, the sulfur fixation principles, and synthesis methods of the TMPs are briefly summarized and the recent progress of TMPs in LSBs is reviewed in detail. Finally, a perspective on the future research directions of LSBs is provided.

In Situ 1D Carbon Chain-Mail Catalyst Assembly for Stable Lithium-Sulfur Full Batteries

The main obstacles for the commercial application of Lithium-Sulfur (Li-S) full batteries are the large volume change during charging/discharging process, the shuttle effect of lithium polysulfide (LiPS), sluggish redox kinetics, and the indisciplinable dendritic Li growth. Especially the overused of metal Li leads to the low utilization of active Li, which seriously drags down the actual energy density of Li-S batteries. Herein, an efficient design of dual-functional CoSe electrocatalyst encapsulated in carbon chain-mail (CoSe@CCM) is employed as the host both for the cathode and anode regulation simultaneously. The carbon chain-mail constituted by carbon encapsulated layer cross-linking with carbon nanofibers protects CoSe from the corrosion of chemical reaction environment, ensuring the high activity of CoSe during the long-term cycles. The Li-S full battery using this carbon chain-mail catalyst with a lower negative/positive electrode capacity ratio (N/P < 2) displays a high areal capacity of 9.68 mAh cm-2 over 150 cycles at a higher sulfur loading of 10.67 mg cm-2 . Additionally, a pouch cell is stable for 80 cycles at a sulfur loading of 77.6 mg, showing the practicality feasibility of this design.

Cathode materials for lithium-sulfur battery: a review

Lithium-sulfur batteries (LSBs) are considered to be one of the most promising candidates for becoming the post-lithium-ion battery technology, which would require a high level of energy density across a variety of applications. An increasing amount of research has been conducted on LSBs over the past decade to develop fundamental understanding, modelling, and application-based control. In this study, the advantages and disadvantages of LSB technology are discussed from a fundamental perspective. Then, the focus shifts to intermediate lithium polysulfide adsorption capacity and the challenges involved in improving LSBs by using alternative materials besides carbon for cathode construction. Attempted alternative materials include metal oxides, metal carbides, metal nitrides, MXenes, graphene, quantum dots, and metal organic frameworks. One critical issue is that polar material should be more favorable than non-polar carbonaceous materials in the aspect of intermediate lithium polysulfide species adsorption and suppress shuttle effect. It will be also presented that by preparing cathode with suitable materials and morphological structure, high-performance LSB can be obtained.

Graphical abstract

Ni Single Atoms on MoS2 Nanosheets Enabling Enhanced Kinetics of Li-S Batteries

The practical application of Li-S batteries is seriously hindered due to its shuttle effect and sluggish redox reaction, which requires a better functional separator to solve the problems. Herein, polypropylene separators modified by MoS₂ nanosheets with atomically dispersed nickel (Ni-MoS₂ ) are prepared to prevent the shuttle effect and facilitate the redox kinetics for Li-S batteries. Compared with pristine MoS₂ nanosheets, Ni-MoS₂ nanosheets exhibit both excellent adsorption and catalysis performance for overcoming the shuttle effect. Assembled with this novel separator, the Li-S batteries exhibit an admirable cycling stability at 2 C over 400 cycles with 0.01% per cycle decaying. In addition, even with a high sulfur loading of 7.5 mg cm^-2 , the battery still provides an initial capacity of 6.9 mAh cm^-2 and remains 5.9 mAh cm^-2 after 50 cycles because of the fast convention of polysulfides catalyzed by Ni-MoS₂ nanosheets, which is further confirmed by the density functional theory (DFT) calculations. Therefore, the proposed strategy is expected to offer a new thought for single atom catalyst applying in Li-S batteries.

Tailoring Lithium Fluoride Interface for Dendrite-Free Lithium Anode to Prolong the Cyclic Stability of Lithium-Sulfur Pouch Cells

Lithium-sulfur (Li-S) cells have been regarded as attractive alternatives to achieve higher energy densities because of their theoretical specific energy far beyond the lithium-ion cells. However, the achieved results of Li-S cells are exaggerating the cycle performance in their pouch formats because the considerable works are based on the coin cells where flood electrolyte and endless Li supply ensure the Li metal with nature structure features, resulting in a negligible effect on cycle performance caused by the Li dendrites and electrolyte dissipation during cycles. Herein, we demonstrate a strategy to enable the Li metal with lithium fluoride (LiF)-rich solid electrolyte interface via integrating a reinforced interface (RI) embedded with nano-LiF particles on the surface of the Li metal anode. The RI interface enables the solvent molecules of the electrolyte to gain fewer electrons from Li anode, resulting in a lower leakage current of assembled RI||Li-S cell (~ 0 μA) than pristine Li anode (~ 1.15 µA). Moreover, these results show that suppressing lithium dendrite growth is more urgent than inhibiting the shuttle effect of polysulfides in the pouch cell format. As a result, the RI layer-engineered Li metal bears witness to the cyclic stability of Li anode over 800 h, thus achieving stable cycles of Ah-scale Li-S pouch cell with an energy density of 410 Wh/kg at a current of 200 mA per cell. Our study demonstrates that the suppression of lithium dendrites by the RI could be a promising method to prolong the cycle number of Li-S pouch cells.

FeCoNi Ternary Nano-Alloys Embedded in a Nitrogen-Doped Porous Carbon Matrix with Enhanced Electrocatalysis for Stable Lithium-Sulfur Batteries

The application of composite materials that combine the advantages of carbonaceous material and metal alloy proves to be a valid method for improving the performance of lithium-sulfur batteries (LSBs). Herein iron-cobalt-nickel (FeCoNi) ternary alloy nanoparticles (FNC) that spread on nitrogen-doped carbon (NC) are obtained by a strategy of low-temperature sol-gel followed by annealing at 800 °C under an argon/hydrogen atmosphere. Benefiting from the synergistic effect of different components of FNC and the conductive network provided by the NC, not only can the "shuttle effect" of lithium polysulfides (LiPS) be suppressed, but also the conversion of LiPS, the diffusion of Li⁺, and the deposition of Li₂S can be accelerated. Taking advantage of those merits, the batteries assembled with an FNC@NC-modified polypropylene (PP) separator (FNC@NC//PP) can deliver a high reversible specific capacity of 1325 mAh g^-1 at 0.2 C and maintain 950 mAh g^-1 after 200 cycles, and they can also achieve a low capacity fading rate of 0.06% per cycle over 500 cycles at 1 C. More impressively, even under harsh test conditions (the ratio of electrolyte to sulfur (E/S) = 6 μL mg^-1 and sulfur loading = 4.7 mg cm^-2 and E/S = 10 μL mg^-1 and sulfur loading = 5.9 mg cm^-2), the area capacity of batteries is still much higher than 4 mAh cm^-2.

Ni3Sn2/nitrogen-doped graphene composite with chemisorption and electrocatalysis as advanced separator modifying material for lithium sulfur batteries

Lithium-sulfur batteries have been widely studied because of their advantages of abundant reserves, environmental friendliness, low cost andhighspecific capacity. However, the volume expansionand the low electrical conductivity of sulfur, and the shuttle effect of polysulfides limit their application. Herein,wesynthesizea two-dimensional layered Ni₃Sn₂/nitrogen-doped graphene (NG) composite asseparator modifying material for lithium-sulfur batteries. The Ni₃Sn₂formed by dual metal salts Ni(NO₃)₂·6H₂O and SnCl₂·2H₂O can adsorb polysulfide and catalyze its transformation to improve the electrochemical reaction kinetics. Moreover, the layered NG can not only disperse the Ni₃Sn₂particles, but alsoensure rapid electron transfer. Therefore, the lithium-sulfur battery with the Ni₃Sn₂/NG modified separator shows excellent electrochemical performance. At a current rate of 1 C, the lithium-sulfur battery with the Ni₃Sn₂/NG modified separator can provide a high initial discharge capacity of 1022.1 mAh g^-1and maintain a reversible specific capacity of 758.3 mAh g^-1after 400 cycles.

Amorphous Boron Carbide on Titanium Dioxide Nanobelt Arrays for High-Efficiency Electrocatalytic NO Reduction to NH3

Electrocatalytic NO reduction is regarded as an attractive strategy to degrade the NO contaminant into useful NH₃ , but the lack of efficient and stable electrocatalysts to facilitate such multiple proton-coupled electron-transfer processes impedes its applications. Here, we report on developing amorphous B_2.6 C supported on a TiO₂ nanoarray on a Ti plate (a-B_2.6 C@TiO₂ /Ti) as an NH₃ -producing nanocatalyst with appreciable activity and durability toward the NO electroreduction. It shows a yield of 3678.6 μg h^-1  cm^-2 and a FE of 87.6 %, superior to TiO₂ /Ti (563.5 μg h^-1  cm^-2 , 42.6 %) and a-B_2.6 C/Ti (2499.2 μg h^-1  cm^-2 , 85.6 %). An a-B_2.6 C@TiO₂ /Ti-based Zn-NO battery achieves a power density of 1.7 mW cm^-2 with an NH₃ yield of 1125 μg h^-1  cm^-2 . An in-depth understanding of catalytic mechanisms is gained by theoretical calculations.

High-Efficiency Hybrid Sulfur Cathode Based on Electroactive Niobium Tungsten Oxide and Conductive Carbon Nanotubes for All-Solid-State Lithium-Sulfur Batteries

All-solid-state lithium-sulfur batteries (ASSLSBs) have become a promising candidate because of their high energy density and safety. To ensure the high utilization and electrochemical capacity of sulfur in all-solid-state batteries, both the electronic and ionic conductivities of the sulfur cathode should be as high as possible. In this work, an intercalation-conversion hybrid cathode is proposed by distributing sulfur evenly on electroactive niobium tungsten oxide (Nb₁₈W₁₆O₉₃) and conductive carbon nanotubes (CNTs) for achieving high performance ASSLSBs. Herein, Nb₁₈W₁₆O₉₃ shows good electrochemical lithium storage in the hybrid cathode, which could serve as an effective Li-ion/electron conductor for the conversion of sulfur in the discharge/charge processes to achieve a high utilization of sulfur. However, CNTs could further increase the electronic conductivity of the hybrid cathode by constructing good conductive frameworks and suppress the volumetric fluctuation during the interconversion of sulfur and Li₂S. With this strategy, the S/Nb₁₈W₁₆O₉₃/CNT cathode achieves a high sulfur utilization of 91% after one cycle activation with a high gravimetric capacity of 1526 mA h g^-1. In addition, excellent rate performance is also obtained at 0.5 C with a reversible capacity of 1262 mA h g^-1 after 1000 cycles. This work offers a new perspective to develop ASSLSBs.

Ultrathin Cobalt Phthalocyanine@Graphene Oxide Layer-Modified Separator for Stable Lithium-Sulfur Batteries

Rechargeable lithium-sulfur (Li-S) batteries have aroused great attention due to their high energy density and low cost. However, Li-S batteries suffer from rapid capacity decay owing to the shuttle effect of the intermediate polysulfides. To tackle this issue, functional separators with the ability to absorb polysulfides play a vital role to block them from passing through the separator. Herein, an ultrathin and lightweight layer of graphene oxide (GO) loaded with Co phthalocyanine (CoPc) is fabricated on a polypropylene (PP) separator. The thickness of CoPc@GO is about 200 nm with a low areal mass of 22 μg cm^-2. CoPc is uniformly dispersed on GO sheets through π-π interactions, which inhibits the shuttle effect and facilitates the conversion of the intermediate polysulfides. In consequence, the battery with a CoPc@GO-PP separator exhibits good cycling stability with a low-capacity decay rate of 0.076% per cycle at 1 C over 400 cycles and a high specific capacity of 919 mA h g^-1 after 250 cycles at 0.5 C.

Sulfur Compensation: A Promising Strategy against Capacity Decay in Li-S Batteries

Drastic capacity decay as a result of active sulfur loss caused by the severe shuttle effect of dissolved polysulfides is the main obstacle in the commercial application of Li-S batteries. Various methods have been developed to suppress the active sulfur loss, but the results are far from ideal. Herein, we propose a facile sulfur compensation strategy to improve the cyclic stability of Li-S batteries. The strategy is to compensate sulfur to the cathode by chemical reactions between additional sulfur and lithium polysulfides diffusing away from the cathode. The compensatory sulfur can effectively mitigate the loss of active sulfur in the cathode side caused by the shuttle effect and thus maintain the high capacity of the battery during charging and discharging for long life cycle assessments. Using this strategy, the specific capacity of the assembled Li-S batteries was maintained at >700 mA h g^-1 for more than 500 cycles at 1 C and >1000 mA h g^-1 for ∼100 cycles at 0.1 C, while the capacity of control batteries rapidly decreased to <200 mA h g^-1 under the same conditions.

Controlled Synthesis of Ultrafine β-Mo2C Nanoparticles Encapsulated in N-Doped Porous Carbon for Boosting Lithium Storage Kinetics

Rational construction of anode material architecture to afford excellent cycling stability, fast rate capacity, and large specific capacity is essential to promote further development of lithium-ion batteries in commercial applications. In this work, we propose a facile strategy to anchor ultrafine β-Mo2C nanoparticles in N-doped porous carbon skeleton (β-Mo2C@NC) using a scalable salt-template method. The well-defined and abundant hierarchical porous structure of β-Mo2C@NC can not only significantly enhance the electron/ion transfer but also markedly increase the specific surface area to effectively expose the electrochemically accessible active sites. Besides, the N-doped carbon matrix can turn the d-orbital electrons of the Mo to boost the electron transportation as well as distribute active sites to buffer the volume change of Mo2C and provide conductive pathways during discharge/charge cycles. As a result, the as-prepared β-Mo2C@NC displays excellent lithium storage performance in terms of 1701.6 mA h g-1 at 0.1 A g-1 after 100 cycles and a large capacity of 816.47 mA h g-1 at 2.0 A g-1 after 500 cycles. The above results distinctly demonstrate that the β-Mo2C@NC composite has potential application as anode materials in high-performance energy storage devices.

Synergistic Adsorption-Catalytic Sites TiN/Ta2O5 with Multidimensional Carbon Structure to Enable High-Performance Li-S Batteries

Lithium-sulfur (Li-S) batteries are deemed to be one of the most optimal solutions for the next generation of high-energy-density and low-cost energy storage systems. However, the low volumetric energy density and short cycle life are a bottleneck for their commercial application. To achieve high energy density for lithium-sulfur batteries, the concept of synergistic adsorptive-catalytic sites is proposed. Base on this concept, the TiN@C/S/Ta₂O₅ sulfur electrode with about 90 wt% sulfur content is prepared. TiN contributes its high intrinsic electron conductivity to improve the redox reaction of polysulfides, while Ta₂O₅ provides strong adsorption capability toward lithium polysulfides (LiPSs). Moreover, the multidimensional carbon structure facilitates the infiltration of electrolytes and the motion of ions and electrons throughout the framework. As a result, the coin Li-S cells with TiN@C/S/Ta₂O₅ cathode exhibit superior cycle stability with a decent capacity retention of 56.1% over 300 cycles and low capacity fading rate of 0.192% per cycle at 0.5 C. Furthermore, the pouch cells at sulfur loading of 5.3 mg cm^-2 deliver a high areal capacity of 5.8 mAh cm^-2 at low electrolyte/sulfur ratio (E/S, 3.3 μL mg^-1), implying a high sulfur utilization even under high sulfur loading and lean electrolyte operation.

Anion-Doped Cobalt Selenide with Porous Architecture for High-Rate and Flexible Lithium-Sulfur Batteries

Emerging catalytic host for sulfur is an effective approach to breaking the limits of lithium-sulfur batteries for practical applications. Herein, the hydrangea-shaped Co_0.85 Se electrocatalyst with macroporous architecture is synthesized. Besides, to improve the electronic conductivity of Co_0.85 Se, some defects (S-doped) are introduced into the structure of crystals. The S-doped Co_0.85 Se exhibited an outstanding electrocatalytic effect on lithium polysulfides conversion and can induce and regulate uniform growth of insoluble Li₂ S on its surface due to the synergistic adsorption by Se and S. As a result, the S/C cathode achieved a high initial capacity of 1340.6 mAh g^-1 at 0.5 C and a stable cycling capacity of 666.6 mAh g^-1 at 1 C after 500 cycles by 5 wt% Co_0.85 SeS additions. Moreover, high S loading cathodes are designed through in situ synthesis of Co_0.85 SeS on flexible carbon cloth (Co_0.85 SeS@CC). The porous and open framework of Co_0.85 SeS@CC facilitated electrolyte infiltration and accommodated the volume change of sulfur during the charge/discharge process. Taking by these advantages, a high areal capacity of 9.663 mAh cm^-2 is achieved at a high sulfur loading of 9.98 mg cm^-2 . Even at a high current density of 15 mA cm^-2 , a reversible capacity of 603.7 mAh g^-1 is maintained at a sulfur loading of 6.52 mg cm^-2 . This proposed work provides a feasible approach to high-rate and flexible Li-S batteries.

All-in-One Sulfur Host: Smart Controls of Architecture and Composition for Accelerated Liquid-Solid Redox Conversion in Lithium-Sulfur Batteries

The development of Li-S batteries (LSBs) is largely impeded by sluggish redox kinetics and notorious polysulfide shuttling. Herein, hierarchical MoC@Ni-NCNT arrays are reported as a multifunctional sulfur host in Li-S batteries, which comprised a flexible carbon fiber cloth substrate decorated with vertical MoC porous nanorods rooted by interconnected nitrogen-doped carbon nanotubes (NCNTs). In the designed host, the inner MoC porous backbone (composed of nanoparticles) along with the in situ-grafted interwoven NCNT shell can greatly maximize the host-guest interactive surface for homogeneous sulfur dispersion, thus realizing decent high-sulfur-loading performance. Ni nanoparticles, encapsulated within NCNTs in the outer shell, act as strong chemical-anchoring centers effectively trap-escaped polysulfides and propel the bidirectional sulfur transformation kinetics. In merit of sufficient adsorption and catalytic sites, the cell configured with the MoC@Ni-NCNT cathode delivers not only high capacity (1421 mA h g^-1 at 0.1 C) but also superior rate performance and ultralong lifespan. The cell can still achieve a superb areal capacity of 6.1 mA h cm² under an increased sulfur loading up to 6 mg cm^-2. This work could open a new avenue for the construction of a multifunctional cathode for high-performance LSBs.

Nano-Confinement of Insulating Sulfur in the Cathode Composite of All-Solid-State Li-S Batteries Using Flexible Carbon Materials with Large Pore Volumes

Durable nanostructured cathode materials for efficient all-solid-state Li-S batteries were prepared using a conductive single-walled 3D graphene with a large pore volume as the cathode support material. At high loadings of the active material (50-60 wt %), microscale phase segregation was observed with a conventional cathode support material during the charging/discharging processes but this was suppressed by the confinement of insulating sulfur into the mesopores of the elastic and flexible nanoporous graphene with a large pore volume of 5.3 mL g^-1. As such, durable three-phase contact was achieved among the solid electrolyte, insulating sulfur, and the electrically conductive carbon. Consequently, the electrochemical performances of the assembled all-solid-state batteries were significantly improved and feasible under the harsh conditions of operation at 353 K, and improved cycling stability as well as the highest specific capacity of 716 mA h per gram of cathode (4.6 mA h cm^-2, 0.2 C) was achieved with high sulfur loading (50 wt %).

Congener Substitution Reinforced Li7P2.9Sb0.1S10.75O0.25 Glass-Ceramic Electrolytes for All-Solid-State Lithium-Sulfur Batteries

Glass-ceramic sulfide solid electrolytes like Li₇P₃S₁₁ are practicable propellants for safe and high-performance all-solid-state lithium-sulfur batteries (ASSLSBs); however, the stability and conductivity issues remain unsatisfactory. Herein, we propose a congener substitution strategy to optimize Li₇P₃S₁₁ as Li₇P_2.9Sb_0.1S_10.75O_0.25 via chemical bond and structure regulation. Specifically, Li₇P_2.9Sb_0.1S_10.75O_0.25 is obtained by a Sb₂O₅ dopant to achieve partial Sb/P and O/S substitution. Benefiting from the strengthened oxysulfide structural unit of POS₃^3- and P₂OS₆^4- with bridging oxygen atoms and a distorted lattice configuration of the Sb-S tetrahedron, the Li₇P_2.9Sb_0.1S_10.75O_0.25 electrolyte exhibits prominent chemical stability and high ionic conductivity. Besides the improved air stability, the ionic conductivity of Li₇P_2.9Sb_0.1S_10.75O_0.25 could reach 1.61 × 10^-3 S cm^-1 at room temperature with a wide electrochemical window of up to 5 V (vs Li/Li⁺), as well as good stability against Li and Li-In alloy anodes. Consequently, the ASSLSB with the Li₇P_2.9Sb_0.1S_10.75O_0.25 electrolyte shows high discharge capacities of 1374.4 mAh g^-1 (0.05C, 50th cycle) at room temperature and 1365.4 mAh g^-1 (0.1C, 100th cycle) at 60 °C. The battery also presents remarkable rate performance (1158.3 mAh g^-1 at 1C) and high Coulombic efficiency (>99.8%). This work provides a feasible technical route for fabricating ASSLSBs.

Advances in Lithium-Sulfur Batteries: From Academic Research to Commercial Viability

Lithium-ion batteries, which have revolutionized portable electronics over the past three decades, were eventually recognized with the 2019 Nobel Prize in chemistry. As the energy density of current lithium-ion batteries is approaching its limit, developing new battery technologies beyond lithium-ion chemistry is significant for next-generation high energy storage. Lithium-sulfur (Li-S) batteries, which rely on the reversible redox reactions between lithium and sulfur, appears to be a promising energy storage system to take over from the conventional lithium-ion batteries for next-generation energy storage owing to their overwhelming energy density compared to the existing lithium-ion batteries today. Over the past 60 years, especially the past decade, significant academic and commercial progress has been made on Li-S batteries. From the concept of the sulfur cathode first proposed in the 1960s to the current commercial Li-S batteries used in unmanned aircraft, the story of Li-S batteries is full of breakthroughs and back tracing steps. Herein, the development and advancement of Li-S batteries in terms of sulfur-based composite cathode design, separator modification, binder improvement, electrolyte optimization, and lithium metal protection is summarized. An outlook on the future directions and prospects for Li-S batteries is also offered.

A Biomass-Based Integral Approach Enables Li-S Full Pouch Cells with Exceptional Power Density and Energy Density

Lithium-sulfur (Li-S) batteries, as part of the post-lithium-ion batteries (post-LIBs), are expected to deliver significantly higher energy densities. Their power densities, however, are today considerably worse than that of the LIBs, limiting the Li-S batteries to very few specific applications that need low power and long working time. With the rapid development of single cell components (cathode, anode, or electrolyte) in the last few years, it is expected that an integrated approach can maximize the power density without compromising the energy density in a Li-S full cell. Here, this goal is achieved by using a novel biomass porous carbon matrix (PCM) in the anode, as well as N-Co9 S8 nanoparticles and carbon nanotubes (CNTs) in the cathode. The authors' approach unlocks the potential of the electrodes and enables the Li-S full pouch cells with unprecedented power densities and energy densities (325 Wh kg-1 and 1412 W kg-1 , respectively). This work addresses the problem of low power densities in the current Li-S technology, thus making the Li-S batteries a strong candidate in more application scenarios.

Confined Thermolysis for Oriented N-Doped Carbon Supported Pd toward Stable Catalytic and Energy Storage Applications

Carbon-based nanomaterials have been widely utilized in catalysis and energy-related fields due to their fascinating properties. However, the controllable synthesis of porous carbon with refined morphology is still a formidable challenge due to inevitable aggregation/fusion of resulted carbon particles during the high-temperature synthetic process. Herein, a hierarchically oriented carbon-structured (fiber-like) composite is fabricated by simultaneously taking advantage of a confined pyrolysis strategy and disparate bond environments within metal-organic frameworks (MOFs). In the resultant composite, the oriented carbon provides a fast mass (molecule/ion/electron) transfer efficiency; the doping-N atoms can anchor or act as active sites; the mesoporous SiO₂ (mSiO₂ ) shell not only effectively prevents the derived carbon or active metal nanoparticles (NPs) from aggregation or leaching, but also acts as a "polysulfide reservoir" in the Li-S batteries to suppress the "shuttle" effect. Benefiting from these advantages, the synthesized composite Pd@NDHPC@mSiO₂ (NDHPC means N-doped hierarchically porous carbon) exhibits extremely high catalytic activity and stability toward the one-pot Knoevenagel condensation-hydrogenation reaction. Furthermore, the oriented NDHPC@mSiO₂ manifests a boosted capacity and cycling stability in Li-S batteries compared to the counterpart that directly pyrolyzes without silica protection. This report provides an effective strategy of fabricating hierarchically oriented carbon composites for catalysis and energy storage applications.

Crystalline Multi-Metallic Compounds as Host Materials in Cathode for Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) battery is one of the most promising next-generation rechargeable batteries. Lots of fundamental research has been done for the problems during cycling like capacity fading and columbic efficiency reducing owing to severe diffusion and migration of polysulfide intermediates. In the early stage, a wide variety of carbon materials are used as host materials for sulfur to enhance electrical conductivity and adsorb soluble polysulfides. Beyond carbon materials, metal based polar compounds are introduced as host materials for sulfur because of their strong catalytic activity and adsorption ability to suppress the shuttle effect. In addition, relatively high density of metal compounds is helpful for increasing volumetric energy density of Li-S batteries. This review focuses on crystalline multi-metal compounds as host materials in sulfur cathodes. The multi-metal compounds involve not only transition metal composite oxides with specific crystalline structures, binary metal chalcogenides, double or complex salts, but also the metal compounds doped or partially substituted by other metal ions. Generally, for the multi-metal compounds, microstructure and morphologies in micro-nano scale are very significant for mass transfer in electrodes; moreover, adsorption and catalytic ability for polysulfides make fast kinetics in the electrode processes.

Natural Cocoons Enabling Flexible and Stable Fabric Lithium-Sulfur Full Batteries

Highlights

A creative cooperative strategy involving silk fibroin/sericin is proposed for stabilizing high-performance flexible Li–S full batteries with a limited Li excess of 90% by simultaneously inhibiting lithium dendrites, adsorbing liquid polysulfides, and anchoring solid lithium sulfides. Such fabric Li–S full batteries offer high volumetric energy density (457.2 Wh L−1), high-capacity retention (99.8% per cycle), and remarkable bending capability (6000 flexing cycles at a small radius of 5 mm).

Abstract

Lithium–sulfur batteries are highly appealing as high-energy power systems and hold great application prospects for flexible and wearable electronics. However, the easy formation of lithium dendrites, shuttle effect of dissolved polysulfides, random deposition of insulating lithium sulfides, and poor mechanical flexibility of both electrodes seriously restrict the utilization of lithium and stabilities of lithium and sulfur for practical applications. Herein, we present a cooperative strategy employing silk fibroin/sericin to stabilize flexible lithium–sulfur full batteries by simultaneously inhibiting lithium dendrites, adsorbing liquid polysulfides, and anchoring solid lithium sulfides. Benefiting from the abundant nitrogen- and oxygen-containing functional groups, the carbonized fibroin fabric serves as a lithiophilic fabric host for stabilizing the lithium anode, while the carbonized fibroin fabric and the extracted sericin are used as sulfiphilic hosts and adhesive binders, respectively, for stabilizing the sulfur cathode. Consequently, the assembled Li–S full battery provided a high areal capacity (5.6 mAh cm−2), limited lithium excess (90%), a high volumetric energy density (457.2 Wh L−1), high-capacity retention (99.8% per cycle), and remarkable bending capability (6000 flexing cycles at a small radius of 5 mm).

Supplementary Information

The online version contains supplementary material available at 10.1007/s40820-021-00609-3.

Cationic covalent-organic framework for sulfur storage with high-performance in lithium-sulfur batteries

Covalent organic frameworks (COFs) with pre-designed structure and customized properties have been employed as sulfur storage materials for lithium-sulfur (Li-S) batteries. In this work, a cationic mesoporous COF (COF-NI) was synthesized by grafting a quaternary ammonium salt group onto the pore channel of COFs via a one-pot three components tandem reaction strategy. The post-functionalized COFs were utilized as the matrix framework to successfully construct the Li-S battery with high-speed capacity and long-term stability. The experimental results showed that, after loading active material sulfur, cationic COF-NI effectively suppressed the shuttle effect of the intermediate lithium polysulfide species in Li-S batteries, and exhibited better cycle stability than the as-obtained neutral COF (COF-Bu). For example, compared with COF-Bu based sulfur cathode (521 mA h g^-1), the cationic COF-NI based sulfur cathode maintained a discharge capacity of 758 mA h g^-1 after 100 cycles. These results clearly showed that appropriate pore environment of COFs can be prepared by rational design, which can reduce the shuttle effect of lithium polysulfide species and improve the performance of Li-S battery.

Construction of reduced graphene oxide wrapped yolk-shell vanadium dioxide sphere hybrid host for high-performance lithium-sulfur batteries

Owing to the considerable theoretical energy density, lithium-sulfur batteries have been deemed as a competitive candidate for the next-generation energy storage devices. However, its commercialization still depends on the moderation of the shuttle effect and the conductivity improvement of the sulfur cathode. Herein, a novel reduced graphene oxide (rGO) wrapped yolk-shell vanadium dioxide (VO2) sphere hybrid host (rGO/VO2) is reported to simultaneously tackle these barriers. In particular, the polar VO2 sphere can chemically anchor and catalyze the conversion of polysulfides effectively both on the yolk and the shell surfaces. Meanwhile, the highly conductive 3D porous rGO network not only allows sufficient penetration of electrolyte and provides efficient transport pathways for lithium ions and electrons, but also buffers the volume variation during the lithiation process. Besides, the dissolution of the polysulfides can also be alleviated by physical confinement via the interconnected carbon network. Benefiting from these synergistic features, such designed rGO/VO2/S cathode delivers outstanding cycle stability (718.6 mA h g-1 initially, and 516.1 mA h g-1 over 400 cycles at 1C) with a fading rate of 0.07% per cycle. Even at 3C, a capacity of 639.7 mA h g-1 is reached. This proposed unique structure could provide novel insights into high-energy batteries.

Metal-Based Electrocatalysts for High-Performance Lithium-Sulfur Batteries: A Review

The lithium-sulfur (Li-S) redox battery system is considered to be the most promising next-generation energy storage technology due to its high theoretical specific capacity (1673 mAh g−1), high energy density (2600 Wh kg−1), low cost, and the environmentally friendly nature of sulfur. Though this system is deemed to be the next-generation energy storage device for portable electronics and electric vehicles, its poor cycle life, low coulombic efficiency and low rate capability limit it from practical applications. These performance barriers were linked to several issues like polysulfide (LiPS) shuttle, inherent low conductivity of charge/discharge end products, and poor redox kinetics. Here, we review the recent developments made to alleviate these problems through an electrocatalysis approach, which is considered to be an effective strategy not only to trap the LiPS but also to accelerate their conversion reactions kinetics. Herein, the influence of different chemical interactions between the LiPS and the catalyst surfaces and their effect on the conversion of liquid LiPS to solid end products are reviewed. Finally, we also discussed the challenges and perspectives for designing cathode architectures to enable high sulfur loading along with the capability to rapidly convert the LiPS.

Rational Design of a Ni3N0.85 Electrocatalyst to Accelerate Polysulfide Conversion in Lithium-Sulfur Batteries

Slow kinetics of polysulfide conversion reactions lead to severe issues for lithium-sulfur (Li-S) batteries, for example, low rate capability, polysulfide migration, and low Coulombic efficiencies. These challenges hinder the practical applications of Li-S batteries. In this study, we proposed a rational strategy of tuning the d-band of catalysts to accelerate the conversion of polysulfides. Nitrogen vacancies were engineered in hexagonal Ni₃N (space group P6₃22) to tune its d-band center, leading to the strong interaction between polysulfides and Ni₃N. Because of the greater electron population in the lowest occupied molecular orbital of Li₂S₄, the terminal S-S bonds were weakened for breaking. Temperature-dependent experiments confirm that Ni₃N_0.85 demonstrates a much low activation energy, thereby accelerating the conversion of polysulfides. A Li-S cell using Ni₃N_0.85 can deliver a high initial discharge capacity of 1445.9 mAh g^-1 (at 0.02 C) and low decay per cycle (0.039%). The Ni₃N_0.85 cell can also demonstrate an initial capacity of 1200.4 mAh g^-1 for up to 100 cycles at a high loading of 5.2 mg cm^-2. The high efficiency of rationally designed Ni₃N_0.85 demonstrates the effectiveness of the d-band tuning strategy to develop low-activation-energy catalysts and to promote the atomic understanding of polysulfide conversion in Li-S batteries.

Mechanical exfoliation of boron carbide: A metal-free catalyst for aerobic oxidative desulfurization in fuel

Metal-free catalysts have been proved to be a low-cost and environmentally friendly species in aerobic oxidative desulfurization (ODS). In this work, exfoliated metal-free boron carbide with few-layered structure, small size, and abundant defects, was first employed in an aerobic ODS system for ultra-deep desulfurization. The exfoliation process was realized by employing a planetary ball mill strategy. Detailed characterizations showed that the ball milling process not only induces thinner layers and small sizes but also introduces numerous defects into the boron carbide catalysts, which is vital in metal-free catalysis. Furthermore, the exfoliated boron carbide catalyst was applied in aerobic ODS system, and 99.5 % of sulfur removal was obtained. Moreover, the catalyst can be recycled 17 times without a significant decrease in catalytic activity. In particular, it was found that ∼90 % of the sulfur compounds in real diesel oil could be removed by the current aerobic ODS system.

Self-Phosphorization of MOF-Armored Microbes for Advanced Energy Storage

Utilization of microbes as the carbon source and structural template to fabricate porous carbon has incentivized great interests owing to their diverse micromorphology and intricate intracellular structure, apart from the obvious benefit of "turning waste into wealth." Challenges remain to preserve the biological structure through the harsh and laborious post-synthetic treatments, and tailor the functionality as desired. Herein, Escherichia coli is directly coated with metal-organic frameworks (MOFs) through in situ assembly to fabricate N, P co-doped porous carbon capsules expressing self-phosphorized metal phosphides. While the MOF coating serves as an armoring layer for facilitating the morphology inheritance from the bio-templates and provides metal sources for generating extra porosity and electrochemically active sites, the P-rich phospholipids and N-rich proteins from the plasma membrane enable carbon matrix doping and further yield metal phosphides. These unique structural and compositional features endow the carbon capsules with great capabilities in suppressing polysulfide shuttling and catalyzing reversible oxygen conversion, ultimately leading to the superb performance of lithium-sulfur batteries and zinc-air batteries. Combining the bio-templating strategy with hierarchical MOF assembly, this work opens a new avenue for the fabrication of highly porous and functional carbon for advanced energy applications.

A Rational Reconfiguration of Electrolyte for High-Energy and Long-Life Lithium-Chalcogen Batteries

Lithium-chalcogen batteries are an appealing choice for high-energy-storage technology. However, the traditional battery that employs liquid electrolytes suffers irreversible loss and shuttle of the soluble intermediates. New batteries that adopt Li⁺ -conductive polymer electrolytes to mitigate the shuttle problem are hindered by incomplete discharge of sulfur/selenium. To address the trade-off between energy and cycle life, a new electrolyte is proposed that reconciles the merits of liquid and polymer electrolytes while resolving each of their inferiorities. An in situ interfacial polymerization strategy is developed to create a liquid/polymer hybrid electrolyte between a LiPF₆ -coated separator and the cathode. A polymer-gel electrolyte in situ formed on the separator shows high Li⁺ transfer number to serve as a chemical barrier against the shuttle effect. Between the gel electrolyte and the cathode surface is a thin gradient solidification layer that enables transformation from gel to liquid so that the liquid electrolyte is maintained inside the cathode for rapid Li⁺ transport and high utilization of active materials. By addressing the dilemma between the shuttle chemistry and incomplete discharge of S/Se, the new electrolyte configuration demonstrates its feasibility to trigger higher capacity retention of the cathodes. As a result, Li-S and Li-Se cells with high energy and long cycle lives are realized, showing promise for practical use.

Engineering Oxygen Vacancies in a Polysulfide-Blocking Layer with Enhanced Catalytic Ability

The practical application of the lithium-sulfur (Li-S) battery is seriously restricted by its shuttle effect, low conductivity, and low sulfur loading. Herein, first-principles calculations are conducted to verify that the introduction of oxygen vacancies in TiO₂ not only enhances polysulfide adsorption but also greatly improves the catalytic ability and both the ion and electron conductivities. A commercial polypropylene (PP) separator decorated with TiO₂ nanosheets with oxygen vacancies (OVs-TiO₂ @PP) is fabricated as a strong polysulfide barrier for the Li-S battery. The thickness of the OVs-TiO₂ modification layer is only 500 nm with a low areal mass of around 0.12 mg cm^-2 , which enhances the fast lithium-ion penetration and the high energy density of the whole cell. As a result, the cell with the OVs-TiO₂ @PP separator exhibits a stable electrochemical behavior at 2.0 C over 500 cycles, even under a high sulfur loading of 7.1 mg cm^-2 , and an areal capacity of 5.83 mAh cm^-2 remains after 100 cycles. The proposed strategy of engineering oxygen vacancies is expected to have wide applications in Li-S batteries.

Facile Synthesis of a "Two-in-One" Sulfur Host Featuring Metallic-Cobalt-Embedded N-Doped Carbon Nanotubes for Efficient Lithium-Sulfur Batteries

The exploration of efficient host materials of sulfur is significant for the practical lithium-sulfur (Li-S) batteries, and the hosts are expected to be highly conductive for high sulfur utilization and exhibit strong interaction toward polysulfides to suppress the shuttle effect for long-lasting cycle stability. Herein, we propose a simple synthesis of metallic cobalt-embedded N-doping carbon nanotubes (Co@NCNT) as a "two-in-one" host of sulfur for efficient Li-S batteries. In the binary host, the N-doped CNTs, cooperating with metallic Co nanoparticles, can serve as 3D conductive networks for fast electron transportation, while the synergetic effect of metallic Co and doping N heteroatoms helps to chemically confine polysulfides, acting as active sites to accelerate electrochemical kinetics. With these advantages, the S/Co@NCNT composite delivers an excellent cycling stability with a capacity decay of 0.08% per cycle averaged within 500 cycles at a current density of 1 A g^-1 and a high rate performance of 530 mA h g^-1 at 5 A g^-1. Further, the superior electrochemical performance of the S/Co@NCNT electrode can be maintained under a high sulfur loading up to 4 mg cm^-2. Our work demonstrates a feasible strategy to design promising host materials simultaneously featuring high conductivity and strong confinement toward polysulfides for high-performance Li-S batteries.

Rational synthesis of a ZIF-67@Co–Ni LDH heterostructure and derived heterogeneous carbon-based framework as a highly efficient multifunctional sulfur host

A core-shelled heterogeneous carbon-based framework induced a smooth “immobilization–diffusion–conversion–deposition” process of polysulfides and significantly improved the performance of Li–S batteries.

A 3D Lithiophilic Mo2 N-Modified Carbon Nanofiber Architecture for Dendrite-Free Lithium-Metal Anodes in a Full Cell

The pursuit for high-energy-density batteries has inspired the resurgence of metallic lithium (Li) as a promising anode, yet its practical viability is restricted by the uncontrollable Li dendrite growth and huge volume changes during repeated cycling. Herein, a new 3D framework configured with Mo₂ N-mofidied carbon nanofiber (CNF) architecture is established as a Li host via a facile fabrication method. The lithiophilic Mo₂ N acts as a homogeneously pre-planted seed with ultralow Li nucleation overpotential, thus spatially guiding a uniform Li nucleation and deposition in the matrix. The conductive CNF skeleton effectively homogenizes the current distribution and Li-ion flux, further suppressing Li-dendrite formation. As a result, the 3D hybrid Mo₂ N@CNF structure facilitates a dendrite-free morphology with greatly alleviated volume expansion, delivering a significantly improved Coulombic efficiency of ≈99.2% over 150 cycles at 4 mA cm^-2 . Symmetric cells with Mo₂ N@CNF substrates stably operate over 1500 h at 6 mA cm^-2 for 6 mA h cm^-2 . Furthermore, full cells paired with LiNi_0.8 Co_0.1 Mn_0.1 O₂ (NMC811) cathodes in conventional carbonate electrolytes achieve a remarkable capacity retention of 90% over 150 cycles. This work sheds new light on the facile design of 3D lithiophilic hosts for dendrite-free lithium-metal anodes.

A review of biomass materials for advanced lithium-sulfur batteries

High energy density and low cost make lithium-sulfur (Li-S) batteries famous in the field of energy storage systems. However, the advancement of Li-S batteries is evidently hindered by the notorious shuttle effect and other issues that occur in sulfur cathodes during cycles. Among various strategies applied in Li-S batteries, using biomass-derived materials is more promising due to their outstanding advantages including strong physical and chemical adsorptions as well as abundant sources, low cost, and environmental friendliness. This review summarizes the recent progress of biomass-derived materials in Li-S batteries. By focusing on the aspects of carbon hosts, separator materials, bio-polymer binders, and all-solid-state electrolytes, the authors aim to shed light on the rational design and utilization of biomass-derived materials in Li-S batteries with high energy density and long cycle lifespan. Perspectives regarding future research opportunities in biomass-derived materials for Li-S batteries are also discussed.

Rational Design of Highly Packed, Crack-Free Sulfur Electrodes by Scaffold-Supported Drying for Ultrahigh-Sulfur-Loaded Lithium-Sulfur Batteries

Despite the notable progress in the development of rechargeable lithium-sulfur batteries over the last decade, achieving high performance with high-sulfur-loaded sulfur cathodes remains a key challenge on the path to the commercialization of practical lithium-sulfur batteries. This paper presents a novel method by which to fabricate a crack-free sulfur electrode with an ultrahigh sulfur loading (16 mg cm^-2) and a high sulfur content (64%). By introducing a porous scaffold on the top of a cast of sulfur cathode slurry, the formation of cracks during the drying of the cast can be prevented due to the lower volume shrinkage of the skin. The scaffold-supported sulfur cathode delivers a notably high capacities of 10.3 mAh cm^-2 and 473 mAh cm^-3 after a prolonged cycle, demonstrating that the crack-free structure renders more uniform redox reactions at such high sulfur loading. The highly packed, crack-free feature of the sulfur cathode is advantageous, given that it reduces the electrolyte uptake to as low as an E/S ratio of 4 μL mg^-1, which additionally contributes to the high energy density. Therefore, the scaffold-supported drying fabrication method as presented here provides an effective route by which to design practically viable, energy-dense lithium-sulfur batteries.

Current Status and Future Prospects of Metal-Sulfur Batteries

Lithium-sulfur batteries are a major focus of academic and industrial energy-storage research due to their high theoretical energy density and the use of low-cost materials. The high energy density results from the conversion mechanism that lithium-sulfur cells utilize. The sulfur cathode, being naturally abundant and environmentally friendly, makes lithium-sulfur batteries a potential next-generation energy-storage technology. The current state of the research indicates that lithium-sulfur cells are now at the point of transitioning from laboratory-scale devices to a more practical energy-storage application. Based on similar electrochemical conversion reactions, the low-cost sulfur cathode can be coupled with a wide range of metallic anodes, such as sodium, potassium, magnesium, calcium, and aluminum. These new "metal-sulfur" systems exhibit great potential in either lowering the production cost or producing high energy density. Inspired by the rapid development of lithium-sulfur batteries and the prospect of metal-sulfur cells, here, over 450 research articles are summarized to analyze the research progress and explore the electrochemical characteristics, cell-assembly parameters, cell-testing conditions, and materials design. In addition to highlighting the current research progress, the possible future areas of research which are needed to bring conversion-type lithium-sulfur and other metal-sulfur batteries into the market are also discussed.

Polysulfide Trapping in Carbon Nanofiber Cloth/S Cathode with a Bifunctional Separator for High-Performance Li-S Batteries

The development of carbon nanofiber (CNF) cloth-based cathodes is essential for the fabrication of high energy density and flexible Li-S batteries. Surface modification is generally used to improve the electrochemical performance of CNF cloth/S cathodes. However, this strategy creates some problems such as structure collapse, complex fabrication steps, and poor consistency. Herein, a β-MnO₂ nanowire/graphene-modified separator is used to improve the performance of CNF cloth/S cathodes without changing their structure. β-MnO₂ can facilitate chemical bonding with polysulfides, whereas graphene can decrease the inner resistance and trap polysulfide by physical shielding. The cathode with the bifunctional separator displayed a high discharge capacity of 529.9 mAh g^-1 with a low capacity decay of 0.051 % per cycle after 500 cycles at 1 C, which is 3 times higher compared with a bare separator. Even with a high sulfur loading of 9.0 mg cm^-2 , a high areal capacity of 3.8 mAh cm^-2 was delivered over 100 cycles.

Co-Fe Mixed Metal Phosphide Nanocubes with Highly Interconnected-Pore Architecture as an Efficient Polysulfide Mediator for Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries have been regarded as one of the most promising candidates for next-generation energy storage owing to their high energy density and low cost. However, the practical deployment of Li-S batteries has been largely impeded by the low conductivity of sulfur, the shuttle effect of polysulfides, and the low areal sulfur loading. Herein, we report the synthesis of uniform Co-Fe mixed metal phosphide (Co-Fe-P) nanocubes with highly interconnected-pore architecture to overcome the main bottlenecks of Li-S batteries. With the highly interconnected-pore architecture, inherently metallic conductivity, and polar characteristic, the Co-Fe-P nanocubes not only offer sufficient electrical contact to the insulating sulfur for high sulfur utilization and fast redox reaction kinetics but also provide abundant adsorption sites for trapping and catalyzing the conversion of lithium polysulfides to suppress the shuttle effect, which is verified by both the comprehensive experiments and density functional theory calculations. As a result, the sulfur-loaded Co-Fe-P (S@Co-Fe-P) nanocubes delivered a high discharge capacity of 1243 mAh g^-1 at 0.1 C and excellent cycling stability for 500 cycles with an average capacity decay rate of only 0.043% per cycle at 1 C. Furthermore, the S@Co-Fe-P electrode showed a high areal capacity of 4.6 mAh cm^-2 with superior stability when the sulfur loading was increased to 5.5 mg cm^-2. More impressively, the prototype soft-package Li-S batteries based on S@Co-Fe-P cathodes also exhibited superior cycling stability with great flexibility, demonstrating their great potential for practical applications.