High-performance Lithium-sulfur Batteries Research Articles

Insights into the aspect ratio effects of ordered mesoporous carbon on the electrochemical performance of sulfur cathode in lithium-sulfur batteries

Tailoring porous host materials, as an effective strategy for storing sulfur and restraining the shuttling of soluble polysulfides in electrolyte, is crucial in the design of high-performance lithium-sulfur (Li-S) batteries. However, for the widely studied conductive hosts such as mesoporous carbon, how the aspect ratio affects the confining ability to polysulfides, ion diffusion as well as the performances of Li-S batteries has been rarely studied. Herein, ordered mesoporous carbon (OMC) is chosen as a proof-of-concept prototype of sulfur host, and its aspect ratio is tuned from over ∼ 2 down to below ∼ 1.2 by using ordered mesoporous silica hard templates with variable length/width scales. The correlation between the aspect ratio of OMCs and the electrochemical performances of the corresponding sulfur-carbon cathodes are systematically studied with combined electrochemical measurements and microscopic characterizations. Moreover, the evolution of sulfur species in OMCs at different discharge states is scrutinized by small-angle X-ray scattering. This study gives insight into the aspect ratio effects of mesoporous host on battery performances of sulfur cathodes, providing guidelines for designing porous host materials for high-energy sulfur cathodes.

Porous FeNi Prussian blue cubes derived carbon-based phosphides as superior sulfur hosts for high-performance lithium–sulfur batteries

In contrast to lithium-ion batteries, lithium–sulfur batteries have higher theoretical energy density and lower cost, so they would become competitive in the practical application. However, the shuttle effect of polysulfides and slow oxidation–reduction kinetics can degrade their electrochemical performance and cycle life. In this work, we have first developed the porous FeNi Prussian blue cubes as precursors. The calcination in different atmospheres was employed to make precursors convert into common pyrolysis products or novel carbon-based phosphides, and sulfides, labeled as FeNiP/A-C, FeNiP/A-P, and FeNiP/A-S. When these products serve as host materials in the sulfur cathode, the electrochemical performance of lithium–sulfur batteries is in the order of S@FeNiP/A-P > S@FeNiP/A-S > S@FeNiP/A-C. Specifically, the initial discharge capacity of S@FeNiP/A-P can reach 679.1 mAh g−1 at 1 C, and the capacity would maintain 594.6 mAh g−1 after 300 cycles. That is because the combination of carbon-based porous structure and numerous well-dispersed Ni2P/Fe2P active sites contribute FeNiP/A-P to obtain larger lithium-ion diffusion, lower resistance, stronger chemisorption, and more excellent catalytic effect than other samples. This work may deliver that metal–organic framework-derived carbon-based phosphides are more suitable to serve as sulfur hosts than carbon-based sulfides or common pyrolysis products for enhancing Li–S batteries’ performance.

Ribosome-inspired electrocatalysts inducing preferential nucleation and growth of three-dimensional lithium sulfide for high-performance lithium-sulfur batteries

Nucleation of lithium sulfide (Li2S) induced by electrocatalysts plays a crucial role in mitigating the shuttle effect. However, short-chain polysulfides on electrocatalysts surfaces tend to re-dissolve into electrolytes, delaying Li2S supersaturation and its nucleation. In this study, we draw inspiration from the ribosome-driven protein synthesis process in cells to prepare ultrasmall nitrogen-doped MoS2 nanocrystals anchored on porous nitrogen-doped carbon networks (N-MoS2-NC) electrocatalysts. Excitedly, the ex-situ SEM demonstrates that ribosome-inspired N-MoS2-NC electrocatalysts induce early nucleation and rapid growth of three-dimensional Li2S during discharge. Theoretical calculations reveal that the Li-S bond length in N-MoS2-Li2S(100) is shorter, and the corresponding interfacial formation energy is lower than in MoS2-Li2S(100). This accelerated conversion of lithium polysulfides to Li2S can enhance the utilization of active substances and inhibit the shuttle effect. This study highlights the potential of ribosome-inspired N-MoS2-NC in improving the electrochemical stability of Li-S batteries, providing valuable insights for future electrocatalyst design.

Nitrogen-doped carbon nanorods embedded with cobalt nanoparticles as separator coatings for high-performance lithium-sulfur batteries

Nitrogen-doped carbon nanorods embedded with cobalt nanoparticles as separator coatings for high-performance lithium-sulfur batteries

The ferrocene-bonding NH2-UIO-66 as an ion sieve to intercept polysulfides and screen Li+ for upgrading performance of lithium-sulfur batteries

Intercepting polysulfides and screening Li+ is one of the most effective methods to achieve high-performance lithium-sulfur (Li-S) batteries. This study focuses on the covalent anchoring of ferrocene into NH2-UIO-66 for the modification of polypropylene (PP) separator. The introduction of ferrocene enables the reduction of the pore size of NH2-UIO-66 from 5.1 Å to 3.9 Å, thereby blocking polysulfides anions and penetrating lithium cations at the molecular level, resulting in significant inhibition in the shuttle effect of polysulfides. The cell with this functional separator exhibits a high initial specific capacity of 1490 mA h g−1 with a capacity decay of 0.018 % after 1000 cycles at 2C. This work provides an effective method of separator modification for high-performance energy storage systems.

Inhibiting shuttle effect of lithium polysulfides by double metal selenides for high-performance lithium–sulfur batteries

Inhibiting shuttle effect of lithium polysulfides by double metal selenides for high-performance lithium–sulfur batteries

DFT insights into the adsorption mechanisms of lithium polysulfides on Ni2P (0001) surface for lithium–sulfur batteries

Reliable and sustainable energy storage systems are crucial for a renewable energy future. The ultrahigh theoretical specific capacity and energy density of lithium–sulfur batteries (LSBs) make them one of the most promising next-generation battery technologies. However, their large-scale applications are seriously limited by rapid capacity fading and poor Coulombic efficiency owing to the shuttling of lithium polysulfides (LiPSs). Herein, we investigate nickel phosphide (Ni2P) as an effective host material to realize high-performance LSBs based on first-principles density functional theory (DFT) calculations. Our calculated adsorption energies of the LiPSs species reveal that the Ni2P(0001) surface possesses moderate to high adsorption strength and the adsorption process is facilitated via charge transfer from the LiPSs to the interacting Ni2P(0001) surface atoms. Due to the strong interactions between Ni2P(0001) and LiPSs (Li2Sx, x = 1, 2, 4, 6 and 8), we observe elongation of the intramolecular Li–S bonds in LiPSs upon their adsorption. The stronger adsorption of Li2S coupled with its spontaneous dissociation suggests a faster charging process could occur on the on Ni2P(0001) surface. These results demonstrate that Ni2P can provide effective anchoring sites for the soluble LiPSs, potentially having implications for the design of electrodes for practical LSBs.

Interfacial "Double-Terminal Binding Sites" Catalysts Synergistically Boosting the Electrocatalytic Li2S Redox for Durable Lithium-Sulfur Batteries.

Catalytic conversion of polysulfides emerges as a promising approach to improve the kinetics and mitigate polysulfide shuttling in lithium-sulfur (Li-S) batteries, especially under conditions of high sulfur loading and lean electrolyte. Herein, we present a separator architecture that incorporates double-terminal binding (DTB) sites within a nitrogen-doped carbon framework, consisting of polar Co0.85Se and Co clusters (Co/Co0.85Se@NC), to enhance the durability of Li-S batteries. The uniformly dispersed clusters of polar Co0.85Se and Co offer abundant active sites for lithium polysulfides (LiPSs), enabling efficient LiPS conversion while also serving as anchors through a combination of chemical interactions. Density functional theory calculations, along with in situ Raman and X-ray diffraction characterizations, reveal that the DTB effect strengthens the binding energy to polysulfides and lowers the energy barriers of polysulfide redox reactions. Li-S batteries utilizing the Co/Co0.85Se@NC-modified separator demonstrate exceptional cycling stability (0.042% per cycle over 1000 cycles at 2 C) and rate capability (849 mAh g-1 at 3 C), as well as deliver an impressive areal capacity of 10.0 mAh cm-2 even in challenging conditions with a high sulfur loading (10.7 mg cm-2) and lean electrolyte environments (5.8 μL mg-1). The DTB site strategy offers valuable insights into the development of high-performance Li-S batteries.

CoO/MoO3@Nitrogen-Doped carbon hollow heterostructures for efficient polysulfide immobilization and enhanced ion transport in Lithium-Sulfur batteries

Lithium-sulfur batteries (LSBs) have emerged as a promising energy storage system, but their practical application is hindered by the polysulfide shuttle effect and sluggish redox kinetics. To address these challenges, we have developed CoO/MoO3@nitrogen-doped carbon (CoO/MoO3@NC) hollow heterostructures based on porous ZIF-67 as separators in LSBs. CoO has a strong anchoring effect on polysulfides. The heterostructure formed after the introduction of MoO3 increases the adsorption of polysulfides. The carbon coating outside the heterostructure improves the ion transmission efficiency of the battery, leading to enhanced electrochemical performance. The modified LSB demonstrates a low-capacity decay rate of 0.092% over 500 cycles at 0.5C, with a high discharge capacity of 613 mAh g−1 at 1C. This work presents a novel approach for the preparation of hollow heterostructure materials, aiming for high-performance LSBs.

Mesoporous NiCo2S4@rGO nanocomposites as sulfur carriers for high performance lithium sulfur batteries

It is of unprecedented significance to surmount the daunting challenges of lithium-sulfur battery due to its low cost and exceptionally high energy density. Herein, the mesoporous NiCo2S4@rGO nanocomposites were fabricated solvothermally with mesoporous NiCo2S4 nanoparticles dispersed on rGO and investigated as highly-efficient carriers for sulfur cathode in lithium-sulfur battery. The as-obtained NiCo2S4@rGO nanocomposites are featured with abundant mesopore, good electronic and ionic conductivity, excellent catalytic effect on the redox of lithium polysulfides conversion and strong adsorption, thus observably accelerating the redox kinetics of lithium polysulfides and suppressing the shuttle effect. Therefore, the NiCo2S4@rGO@S electrode delivers a high reversible specific discharge density of 785 mAh g−1 at 0.1 C after 100 cycles and exhibits good rate capability and cycling stability, verifying its great promising for the commercial application of lithium-sulfur battery.

Cobalt-iron layered double hydroxides/CNTs composite modified separator enabling high-performance lithium–sulfur batteries

The active material loss and capacity degeneration resulted from severe shuttle effect and sluggish redox reaction kinetics of lithium polysulfides (LiPSs) have greatly hindered the further development of high-performance lithium–sulfur batteries (LiSBs). Herein, the functional polymer separator consisting of cobalt-iron layered double hydroxides (CoFe LDH)/carbon nanotubes (CNTs) modified polymer separator is developed. This CoFe LDH/CNTs composite combines the advantages of enhanced chemical bonding between CoFe LDH and LiPSs and improved conductivity, which can significantly suppress the shuttling effect of LiPSs and accelerate the redox reaction kinetics. Therefore, LiSBs assembled by CoFe LDH/CNT-modified separators exhibit superior electrochemical performance with high initial capacity (961.4 mAh g−1) and excellent cycling stability during 200 cycles at 0.5 C rate. The results demonstrate that the Co-Fe LDH/CNTs composites are efficient functional separators for for high-performance LiSBs.

Laser induction of hierarchically micro/nanostructured CoNi-LDH/C composite for high-performance lithium-sulfur batteries

Li-S batteries suffer from limited electronic conductivity and shuttle effect of soluble LiPSs, which can hinder redox kinetics and reduce overall electrochemical performance. To solve these issues, we propose a strategy to synthesize a CoNi-layered double hydroxide/carbon composite (L-CoNi-LDH/C) through laser treatment and hydrothermal reaction. The resulting L-CoNi-LDH/C composite possesses a high specific surface area, enabling effectively anchor sulfur molecules and adsorb LiPSs. Moreover, the 2D layered structure of LDH and porous carbon framework can facilitate electron and ion transport. The Co and Ni species in the LDH structure act as catalysts, promoting the conversion of LiPSs into Li2S/Li2S2 and enhancing redox kinetics. A Li-S battery using CoNi-LDH/C as S host (S@CoNi-LDH/C) shows an initial capacity of 1574 mAh g−1 and maintains a reversible capacity of 1097 mAh g−1 after 100 cycles.

WITHDRAWN: Progress in the advancement of medium- and high-entropy catalysts for high performance lithium-sulfur batteries

Lithium-sulfur batteries have attracted significant attention as a potential new energy storage system, thanks to their high theoretical energy density, cost-effectiveness, and environmentally friendly nature. However, the practical implementation of lithium-sulfur batteries faces inherent challenges, such as rapid capacity decay and poor cycling stability due to the dissolution of lithium polysulfides during cycling. Recent advances have made considerable progress in addressing these challenges by incorporating catalysts to facilitate redox reactions and control the shuttle effect. A notable trend in this regard is the emergence of medium- and high-entropy materials as an innovative approach to designing advanced catalysts, positioning them as promising candidates for multimetallic-based catalysts in lithium-sulfur batteries. This review examines the progress and application of medium- and high-entropy materials, including alloys, oxides, sulfides, phosphides, and prussian blue analogues, as catalysts for lithium-sulfur batteries. It explores the effects of various factors and their synergistic impacts on electrochemical performance, along with discussions on strategies of optimizing catalyst design for the improved sulfur utilization and cycling stability. Additionally, the review discusses the challenges, potential future directions, and prospects for designing medium- and high-entropy materials-based catalysts, envisioning the development of high-performance lithium-sulfur batteries for future energy storage applications.

Sulfur electrode tolerance and polysulfide conversion promoted by the supramolecular binder with rare-earth catalysis in lithium-sulfur batteries

The binder that maintains electrode integrity and provides electron/ion transport channels is insufficient for high-performance lithium-sulfur (Li-S) batteries. Multifunctional and environmentally friendly binders with minimal lithium polysulfides (LiPSs) escape and accelerated LiPSs conversion kinetics are critical for sustainable Li-S batteries. Herein, we proposed a new versatile supramolecular polymer binder synthesized by hydrogen bonding crosslinking between hydrolysable polymer matrix and yttrium-pyridine complex in aqueous solutions, denoted as GB-Y. This unique environmental-friendly binder based on supramolecular chemistry could (1) maintain the integrity of sulfur cathode through the mechanical toughness contributed by synergistic effect of hydrogen bonds and robust chemical bonds, (2) anchor LiPSs by lithiophilic effects, and (3) accelerate LiPSs conversion by electrocatalysis of rare-earth catalysis sites (Y3+) as Lewis acids. With above benefits of GB-Y binder, the Li-S batteries with GB-Y binder deliver a high discharge capacity of 1201.5 mAh g−1 and an excellent cyclability over 800 cycles. This binder exhibits a commercial potential in view of capacity release under high-sulfur loading of 6.56 mg cm−2 with lean electrolyte (electrolyte/sulfur (E/S) ratio of 10 μl mg−1). This study provides a concept of binders with three efficacies, i.e. adhesion, adsorption, and catalysis, and offers an innovative and environmentally friendly strategy for the construction of advanced binder with supramolecular chemistry manner to promote the practical application of Li-S batteries.

Organic Electrolyte Additive: Dual Functions Toward Fast Sulfur Conversion and Stable Li Deposition for Advanced Li-S Batteries.

Lithium-sulfur (Li-S) battery is of great potential for the next generation energy storage device due to the high specific capacity energy density. However, the sluggish kinetics of S redox and the dendrite Li growth are the main challenges to hinder its commercial application. Herein, an organic electrolyte additive, i.e., benzyl chloride (BzCl), is applied as the remedy to address the two issues. In detail, BzCl can split into Bz· radical to react with the polysulfides, forming a Bz-S-Bz intermediate, which changes the conversion path of S and improves the kinetics by accelerating the S splitting. Meanwhile, a tight and robust solid electrolyte interphase (SEI) rich in inorganic ingredients namely LiCl, LiF, and Li2O, is formed on the surface of Li metal, accelerating the ion conductivity and blocking the decomposition of the solvent and lithium polysulfides. Therefore, the Li-S battery with BzCl as the additive remains high capacity of 693.2mAhg-1 after 220 cycles at 0.5C with a low decay rate of 0.11%. This work provides a novel strategy to boost the electrochemical performances in both cathode and anode and gives a guide on the electrolyte design toward high-performance Li-S batteries.

Niobium Boride/Graphene Directing High-Performance Lithium-Sulfur Batteries Derived from Favorable Surface Passivation.

Efficient catalysts are needed to accelerate the conversion and suppress the shuttling of polysulfides (LiPSs) to promote the further development of lithium-sulfur (Li-S) batteries. Intermetallic niobium boride (NbB2) has indefinite potential due to superior catalytic activity. Nonetheless, the lack of a rational understanding of catalysis creates a challenge for the design of catalysts. Herein, a NbB2/reduced graphene oxide-modified PP separator (NbB2/rGO/PP) is rationally designed. Essential, an in-depth insight into the catalysis mechanism of NbB2 toward LiPSs is established based on experiments and multiperspective measurement characterization, ab initio molecular dynamics (AIMD), and density functional theory (DFT). It has been uncovered that the actual catalyst that interacts with LiPSs in NbB2 is the passivated surface with an oxide layer (O2-NbB2), which occurs through B-O-Li and Nb-O-Li bonds, rather than the clean NbB2 surface. And the decomposition barrier of Li2S is greatly reduced by a substantial margin, dropping from 3.390 to 0.93 and 0.85 eV on the Nb-O and B-O surfaces, respectively, with fast Li+ diffusivity. Consequently, the cell with NbB2/rGO/PP as a functional separator achieves a high discharge capacity of 873 mAh g-1 at 1C after 100 cycles. Moreover, the benefits of NbB2/rGO/PP can be effectively maintained even at a high sulfur loading of 7.06 mg cm-2 without significant reduction and with a low electrolyte/sulfur ratio of 8 μL mg-1s. This study enhances our understanding of the catalytic mechanism of Li-S systems and presents a promising approach for developing electrocatalysts that are resilient to poisoning.

Encapsulating Sulfur into a Gel-Derived Nitrogen-Doped Mesoporous and Microporous Carbon Sponge for High-Performance Lithium-Sulfur Batteries.

The practical application of Li-S batteries (LSBs) has long been impeded by the inefficient utilization of sulfur and slow kinetics. Utilizing conductive carbonaceous frameworks as a host scaffold presents an efficient and cost-effective approach to enhance sulfur utilization for redox reactions in LSBs. However, the interaction of pure carbon materials with lithium polysulfide intermediates (LiPSs) is limited to weak van der Waals forces. Hence, the development of an economical method for synthesizing heteroatom-doped carbon materials for sulfur fixation is of paramount importance. In this study, we introduce a hierarchical porous nitrogen-doped carbon sponge (NPCS) with an exceptionally high BET surface area of 3182.2 m2 g-1, achieved through a facile template-assisted polymerization method. The incorporation of inorganic salts, free radical polymerization, and deuteric freeze-drying techniques facilitates the formation of hierarchical pores within the NPCS. After sulfur fixation, the resulting S/NPCS electrode demonstrates remarkable electrochemical performance in LSBs. Specifically, it achieves an 80% sulfur utilization rate, maintains a high reversible specific capacity of 400 mA h g-1 even after 600 cycles at a demanding current density of 5.0 A g-1, and exhibits superior rate capability. It is believed that this work will inspire the rational design of cost-effective carbon-based electrodes for high-performance LSBs.

SnS/SnS2 Heterostructures Embedded in Hierarchical Porous Carbon as Polysulfides Immobilizer for High-Performance Lithium-Sulfur Batteries.

Driven by the strong adsorptive and catalytic ability of metal sulfides for soluble polysulfides, it is considered as a potential mediator to resolve the problems of shuttle effect and slow reaction kinetics of polysulfides in lithium-sulfur (Li-S) batteries. However, their further development is limited by poor electrical conductivity and bad long-term durability. Herein, one type of new catalyst composed of SnS/SnS2 heterostructures on hierarchical porous carbon (denoted as SnS/SnS2-HPC) by a simple hydrothermal method is reported and used as an interlayer coating on the conventional separator for blocking polysulfides. The SnS/SnS2-HPC integrates the advantages of a porous conductive network for promoting the transport of electrons and an enhanced electrocatalyst for accelerating polysulfides conversion. As a result, such a cell coupled with a SnS/SnS2-HPC interlayer exhibits a long-term lifespan of 1200 cycles. This work provides a new cell configuration by using heterostructures with a built-in electric field formed from a p-n heterojunction to improve the performance of Li-S batteries.

Fe2O3-decorated hollow CNT as efficient cathode coatings for high-performance lithium-sulfur batteries

The performance of lithium-sulfur batteries is hindered by the negative impact of polysulfide shuttling and slow sulfur redox kinetics. To achieve high-performance lithium-sulfur batteries, it is necessary to eliminate or reduce the dissolution and diffusion of polysulfides. Herein, this work reports the utilization of Fe2O3-decorated hollow carbon nano-tubes (Fe2O3@CNT) as efficient cathode coatings to trap polysulfides, which has led to accelerated reaction kinetics and improved catalytic activity for polysulfide conversion. These attributes enable Fe2O3@CNT cathode coating battery to deliver an initial discharge-specific capacity of 1273 mAh g−1 at 0.1 C and only experience a capacity decay of 0.067% per cycle over 800 cycles at 1 C. These findings demonstrate that Fe2O3@CNT is a promising cathode coating material with the potential to significantly improve the performance of lithium-sulfur batteries by reducing polysulfide shuttling and enhancing reaction kinetics.

Ni-Ce bimetal doping and phosphating modulated MOF with improved catalysis and adsorption for high-performance lithium-sulfur battery applications

Lithium-sulfur batteries (LSBs) have received widespread attentions because of high specific capacity and low cost. However, the low sulfur utilization and shuttle effect limited their wide application. In this paper, phosphating Ni-Ce bimetallic nanoparticles embedded in multifunctional freestanding porous carbon with improved catalytic activity and confinement were prepared from MOF materials. Compared with monoatomic catalysts or other homonuclear diatomic mixtures, the catalytic-adsorptive synergistic effect of Ni-Ce doping in NiCe@CPS can provide more active sites to catalyze the conversion of lithium polysulfides (LiPSs) to improve the reaction kinetics effectively, meanwhile, the phosphides Ni2P and CeP can physically and chemically adsorb the LiPSs to further inhibit the shuttle effect. Moreover, the porous carbon structure not only provides abundant channels for Li+ transport and electrolyte permeation but greatly facilitates sulfur storage and mitigates the volume expansion during the cycling process. The battery assembled with NiCe@CPS cathode delivered a discharge-specific capacity of 1013 mAh g−1 at 0.1 C, and maintained 768 mAh g−1 after 100 cycles with a Coulombic efficiency of 95 %.