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1.
A NaSICON‐type Li+‐ion conductive membrane with a formula of Li1+ x Y x Zr2? x (PO4)3 (LYZP) (x = 0–0.15) has been explored as a solid‐electrolyte/separator to suppress polysulfide‐crossover in lithium‐sulfur (Li‐S) batteries. The LYZP membrane with a reasonable Li+‐ion conductivity shows both favorable chemical compatibility with the lithium polysulfide species and exhibits good electrochemical stability under the operating conditions of the Li‐S batteries. Through an integration of the LYZP solid electrolyte with the liquid electrolyte, the hybrid Li‐S batteries show greatly enhanced cyclability in contrast to the conventional Li‐S batteries with the porous polymer (e.g., Celgard) separator. At a rate of C/5, the hybrid Li ||LYZP|| Li2S6 batteries developed in this study (with a Li‐metal anode, a liquid/LYZP hybrid electrolyte, and a dissolved lithium polysulfide cathode) delivers an initial discharge capacity of ≈1000 mA h g?1 (based on the active sulfur material) and retains ≈90% of the initial capacity after 150 cycles with a low capacity fade‐rate of <0.07% per cycle.  相似文献   

2.
Room‐temperature Li/Na‐S batteries are promising energy storage solutions, but unfortunately suffer from serious cycling problems rooted in their polysulfide intermediates. The conventional strategy to tackle this issue is to design host materials for trapping polysulfides via weak physical confinement and interfacial chemical interactions. Even though beneficial, their capability for the polysulfide immobilization is still limited. Herein, the unique sulfiphilic nature of metallic Cu is revisited. Upon the exposure to polysulfide in aqueous or aprotic solution, the surface sulfidization rapidly takes place, resulting in the formation of Cu2S nanoflake arrays with tunable texture. When the sulfidized Cu current collector is directly used as the sulfur‐equivalent cathode, it enables high‐performance Li/Na‐S batteries at room temperature with reasonable high sulfur loading. Specific capacities up to ≈1200 mAh g?1 for Li‐S and ≈400 mAh g?1 for Na‐S are measured when normalized to the amount of equivalent sulfur, and can be readily sustained for >1000 cycles.  相似文献   

3.
The insulating nature of sulfur, polysulfide shuttle effect, and lithium‐metal deterioration cause a decrease in practical energy density and fast capacity fade in lithium‐sulfur (Li‐S) batteries. This study presents an integrated strategy for the development of hybrid Li‐S batteries based on a gel sulfur cathode, a solid electrolyte, and a protective anolyte composed of a highly concentrated salt electrolyte containing mixed additives. The dense solid electrolyte completely blocks polysulfide diffusion, and also makes it possible to investigate the cathode and anode independently. This gel cathode effectively traps the polysulfide active material while maintaining a low electrolyte to sulfur ratio of 5.2 mL g?1. The anolyte effectively protects the Li metal and suppresses the consumption of liquid electrolyte, enabling stable long‐term cycling for over 700 h in Li symmetric cells. This advanced design can simultaneously suppress the polysulfide shuttle, protect Li metal, and reduce the liquid electrolyte usage. The assembled hybrid batteries exhibit remarkably stable cycling performance over 300 cycles with high capacity. Finally, surface‐sensitive techniques are carried out to directly visualize and probe the interphase formed on the surface of the Li1.5Al0.5Ge1.5(PO4)3 (LAGP) pellet, which may help stabilize the solid–liquid interface.  相似文献   

4.
The altering of electronic states of metal oxides offers a promising opportunity to realize high‐efficiency surface catalysis, which play a key role in regulating polysulfides (PS) redox in lithium–sulfur (Li–S) batteries. However, little effort has been devoted to understanding the relationship between the electronic state of metal oxides and a catalyst's properties in Li–S cells. Herein, defect‐rich heterojunction electrocatalysts composed of ultrathin TiO2‐x nanosheets and carbon nanotubes (CNTs) for Li–S batteries are reported. Theoretical simulations indicate that oxygen vacancies and heterojunction can enhance electronic conductivity and chemical adsorption. Spectroscopy and electrochemical techniques further indicate that the rich surface vacancies in TiO2‐x nanosheets result in highly activated trapping sites for LiPS and lower energy barriers for fast Li ion mobility. Meanwhile, the redistribution of electrons at the heterojunction interfaces realizes accelerated surface electron exchange. Coupled with a polyacrylate terpolymer (LA132) binder, the CNT@TiO2‐x–S electrodes exhibit a long cycle life of more than 300 cycles at 1 C and a high area capacity of 5.4 mAh cm?2. This work offers a new perspective on understanding catalyst design in energy storage devices through band engineering.  相似文献   

5.
The lithium–sulfur (Li–S) battery is regarded as a next‐generation energy storage system due to its conspicuous merits in high theoretical capacity (1672 mAh g?1), overwhelming energy density (2600 Wh kg?1), and the cost‐effectiveness of sulfur. However, the practical application of Li–S batteries is still handicapped by a multitude of key challenges, mainly pertaining to fatal lithium polysulfide (LiPS) shuttling and sluggish sulfur redox kinetics. In this respect, rationalizing electrocatalytic processes in Li–S chemistry to synergize the entrapment and conversion of LiPSs is of paramount significance. This review summarizes recent progress and well‐developed strategies of the mediator design toward promoted Li–S chemistry. The current advances, existing challenges, and future directions are accordingly highlighted, aiming at providing in‐depth understanding of the sulfur reaction mechanism and guiding the rational mediator design to realize high‐energy and long‐life Li–S batteries.  相似文献   

6.
A rechargeable battery that uses sulfur at the cathode and a metal (e.g., Li, Na, Mg, or Al) at the anode provides perhaps the most promising path to a solid‐state, rechargeable electrochemical storage device capable of high charge storage capacity. It is understood that solubilization in the electrolyte and loss of sulfur in the form of long‐chain lithium polysulfides (Li2Sx, 2 < x < 8) has hindered development of the most studied of these devices, the rechargeable Li‐S battery. Beginning with density‐functional calculations of the structure and interactions of a generic lithium polysulfide species with nitrile containing molecules, it is shown that it is possible to design nitrile‐rich molecular sorbents that anchor to other components in a sulfur cathode and which exert high‐enough binding affinity to Li2Sx to limit its loss to the electrolyte. It is found that sorbents based on amines and imidazolium chloride present barriers to dissolution of long‐chain Li2Sx and that introduction of as little as 2 wt% of these molecules to a physical sulfur‐carbon blend leads to Li‐S battery cathodes that exhibit stable long‐term cycling behaviors at high and low charge/discharge rates.  相似文献   

7.
Lithium–sulfur batteries (LSBs) are currently considered as promising candidates for next‐generation energy storage technologies. However, their practical application is hindered by the critical issue of the polysulfide‐shuttle. Herein, a metal organic framework (MOF)‐derived solid electrolyte is presented to address it. The MOF solid electrolyte is developed based on a Universitetet i Oslo (UIO) structure. By grafting a lithium sulfonate (‐SO3Li) group to the UIO ligand, both the ionic conductivity and the polysulfide‐suppression capability of the resulting ‐SO3Li grafted UIO (UIOSLi) solid electrolyte are greatly improved. After integrating a Li‐based ionic liquid (Li‐IL), lithium bis(trifluoromethanesulfonyl)imide in 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide, the resulting Li‐IL/UIOSLi solid electrolyte exhibits an ionic conductivity of 3.3 × 10?4 S cm?1 at room temperature. Based on its unique structure, the Li‐IL/UIOSLi solid electrolyte effectively restrains the polysulfide shuttle and suppresses lithium dendritic growth. Lithium–sulfur cells with the Li‐IL/UIOSLi solid electrolyte and a Li2S6 catholyte show stable cycling performance that preserves 84% of the initial capacity after 250 cycles with a capacity‐fade rate of 0.06% per cycle.  相似文献   

8.
Lithium–sulfur (Li–S) batteries have the potential to be as efficient and as widespread as lithium‐ion (Li‐ion) batteries, since sulfur electrode has high theoretical capacity (1672 mA h gsul?1) and this element is affordable. However, unlike their ubiquitous lithium ion (Li‐ion) counterparts, it is difficult to realize the commercialization of Li‐S battery. Because the shuttle effect of polysulfide inevitably results in the serious capacity degradation. Tremendous progress is devoted to approach this problem from the aspect of physical confinement and chemisorption of polysulfide. Owing to weak intermolecular interactions, physical confinement strategy, however is not effective when the battery is cycled long‐term. Chemisorption of polysulfide that derived from polar–polar interaction, Lewis acid–base interaction, and sulfur‐chain catenation, are proven to significantly suppress the shuttle effect of polysulfide. It is also discovered that the metal compounds have strong chemical interactions with polysulfide. Therefore, this review focuses on latest metal–organic frameworks metal sulfides, metal hydroxides, metal nitrides, metal carbides, and discusses how the chemical interactions couple with the unique properties of these metal compounds to tackle the problem of polysulfide shuttle effect.  相似文献   

9.
Lithium‐sulfur (Li–S) batteries are one of the most promising alternative energy storage systems beyond Li‐ion batteries. However, the sluggish kinetics of the nucleation and growth of the solid discharge product of Li2S/Li2S2 in the lower discharge plateau has been recently identified as a critical hurdle for attaining high specific capacity in Li–S batteries with high sulfur loadings under lean electrolyte conditions. Herein, a new strategy of breaking the charge‐transport bottleneck by successful generation of experimentally verified stable Li2S2 and a reservoir of quasi‐solid lithium polysulfides within the micropores of activated carbon fiber cloth as a high‐sulfur‐loading host is proposed. The developed Li–S cell is capable of delivering a highly sustainable areal capacity of 6.0 mAh cm?2 under lower electrolyte to sulfur ratios (<3.0 mLE gS?1). Micropore confinement leads to generation of solid Li2S2 that enables high utilization of the entire electroactive area by its inherent self‐healing capacity. This strategy opens a new avenue for rational material designs for Li–S batteries under lean electrolyte condition.  相似文献   

10.
Lithium–sulfur (Li–S) batteries have the potential to be as efficient and as widespread as lithium‐ion (Li‐ion) batteries, since sulfur electrode has high theoretical capacity (1672 mA h gsul?1) and this element is affordable. However, unlike their ubiquitous lithium ion (Li‐ion) counterparts, it is difficult to realize the commercialization of Li‐S battery. Because the shuttle effect of polysulfide inevitably results in the serious capacity degradation. Tremendous progress is devoted to approach this problem from the aspect of physical confinement and chemisorption of polysulfide. Owing to weak intermolecular interactions, physical confinement strategy, however is not effective when the battery is cycled long‐term. Chemisorption of polysulfide that derived from polar–polar interaction, Lewis acid–base interaction, and sulfur‐chain catenation, are proven to significantly suppress the shuttle effect of polysulfide. It is also discovered that the metal compounds have strong chemical interactions with polysulfide. Therefore, this review focuses on latest metal–organic frameworks metal sulfides, metal hydroxides, metal nitrides, metal carbides, and discusses how the chemical interactions couple with the unique properties of these metal compounds to tackle the problem of polysulfide shuttle effect.  相似文献   

11.
Spinel‐layered composites, where a high‐voltage spinel is incorporated in a layered lithium‐rich (Li‐rich) cathode material with a nominal composition x{0.6Li2MnO3 · 0.4[LiCo0.333Mn0.333Ni0.333]O2} · (1 – x) Li[Ni0.5Mn1.5]O4 (x = 0, 0.3, 0.5, 0.7, 1) are synthesized via a hydroxide assisted coprecipitation route to generate high‐energy, high‐power cathode materials for Li‐ion batteries. X‐ray diffraction patterns and the cyclic voltammetry investigations confirm the presence of both the parent components in the composites. The electrochemical investigations performed within a wide potential window show an increased structural stability of the spinel component when incorporated into the composite environment. All the composite materials exhibit initial discharge capacities >200 mAh g–1. The compositions with x = 0.5 and 0.7 show excellent cycling stability among the investigated materials. Moreover, the first cycle Coulombic efficiency achieve a dramatic improvement with the incorporation of the spinel component. More notably, the composite materials with increased spinel component exhibit superior rate capability compared with the parent Li‐rich material especially together with the highest capacity retention for x = 0.5 composition, making this as the optimal high‐energy high‐power material. The mechanisms involved in the symbiotic relationship of the spinel and layered Li‐rich components in the above composites are discussed.  相似文献   

12.
Lithium–sulfur (Li–S) batteries are being considered as one of the most promising candidates for the development of next‐generation energy storage technologies. Although much progress has been made over the past decade, the development of Li–S batteries is still held back by a crucial polysulfide‐shuttle problem. To address this critical issue, an approach to reduce the pore size of the separator is presented here, to prevent the penetration of soluble polysulfide species. A polymer with intrinsic nanoporosity (PIN) is developed within the micrometer‐scale pores of a polypropylene separator. The framework of polypropylene acts as a skeleton to sustain reliable mechanical properties with the thin membrane. Upon the formation of PIN in the pores, the polypropylene separator maintains its thickness. With the thin PIN–polypropylene membrane, the Li–S cells can be operated with a relatively high sulfur loading. The PIN allows the transport of Li+ ions, but suppresses the penetration of the polysulfide species. The Li–S batteries with the PIN‐modified polypropylene separator exhibit enhanced cycling performance.  相似文献   

13.
The detrimental shuttle effect in lithium–sulfur batteries mainly results from the mobility of soluble polysulfide intermediates and their sluggish conversion kinetics. Herein, presented is a multifunctional catalyst with the merits of strong polysulfides adsorption ability, superior polysulfides conversion activity, high specific surface area, and electron conductivity by in situ crafting of the TiO2‐MXene (Ti3C2Tx) heterostructures. The uniformly distributed TiO2 on MXene sheets act as capturing centers to immobilize polysulfides, the hetero‐interface ensures rapid diffusion of anchored polysulfides from TiO2 to MXene, and the oxygen‐terminated MXene surface is endowed with high catalytic activity toward polysulfide conversion. The improved lithium–sulfur batteries deliver 800 mAh g?1 at 2 C and an ultralow capacity decay of 0.028% per cycle over 1000 cycles at 2 C. Even with a high sulfur loading of 5.1 mg cm?2, the capacity retention of 93% after 200 cycles is still maintained. This work sheds new insights into the design of high‐performance catalysts with manipulated chemical components and tailored surface chemistry to regulate polysulfides in Li–S batteries.  相似文献   

14.
Despite the 3–5 fold higher energy density than the conventional Li‐ion cells at a lower cost, commercialization of Li–S batteries is hindered by the insulating nature of sulfur and the dissolution of intermediate polysulfides (Li2S X , 4 < X ≤ 8) into the electrolyte. The authors demonstrate here multichannel carbon nanofibers that are composed of parallel mesoporous channels connected with micropores as sulfur containment. In addition, hydroxyl functional groups are formed on the carbon surface through a chemical activation to enhance the interaction between sulfur and carbon. In the sulfur embedded composite, the mesoporous multichannel enhances the active material utilization and sulfur loading, while the micropores act as a reaction chamber for sulfur component and trap site for polysulfide with the assistance of the functional groups. This sulfur–carbon composite electrode with 2.2 mg cm?2 sulfur displays excellent performance with high rate capability (initial capacity of 1351 mA h g?1 at C/5 rate and 847 mA h g?1 at 5C rate), maintaining 920 mA h g?1 even after 300 cycles (a decay of 0.07% per cycle). Furthermore, a stable reversible capacity of as high as ≈1100 mA h g?1 is realized with a higher sulfur loading of 4.6 mg cm?2.  相似文献   

15.
There is a critical need to evaluate lithium–sulfur (Li–S) batteries with practically relevant high sulfur loadings and minimal electrolyte. Under such conditions, the concentration of soluble polysulfide intermediates in the electrolyte drastically increases, which can alter the fundamental nature of the solution‐mediated discharge and thereby the total sulfur utilization. In this work, an investigation into various high donor number (DN) electrolytes that allow for increased polysulfide dissolution is presented, and the way in which this property may in fact be necessary for increasing sulfur utilization at low electrolyte and high loading conditions is demonstrated. The solvents dimethylacetamide, dimethyl sulfoxide, and 1‐methylimidazole are holistically evaluated against dimethoxyethane as electrolyte co‐solvents in Li–S cells, and they are used to investigate chemical and electrochemical properties of polysulfide species at both dilute and practically relevant conditions. The nature of speciation exhibited by lithium polysulfides is found to vary significantly between these concentrations, particularly with regard to the S3?? species. Furthermore, the extent of the instability in conventional electrolyte solvents and high DN solvents with both lithium metal and polysulfides is thoroughly investigated. These studies establish a basis for future efforts into rationally designing an optimal electrolyte for a lean electrolyte, high energy density Li–S battery.  相似文献   

16.
Lithium–sulfur (Li–S) batteries have attracted increasing attention due to their extremely high theoretical specific capacity and a promising power density. However, practical applications of Li–S batteries are still limited by the relatively low performance, owing to poor conductivity of sulfur itself and discharge products (Li2S/Li2S2) as well as the shuttle effect of the intermediate polysulfide. Herein, honeycomb‐like mesoporous Co, N‐doped carbon nanosheets (MC‐NS) with a high specific surface area and abundant defects are developed which, simultaneously enable polysulfide confinement and highly efficient conversion. Moreover, density functional theory calculations and experiments show that the Co‐N‐C catalytic site as well as defects on the carbon skeleton of the MC‐NS facilitate high efficiency in suppressing the shuttle effect of polysulfides. In situ Raman spectra further demonstrate the enhancement of adsorption ability and conversion efficiency of polysulfides on this host. As a result, the MC‐NS enables much increased specific capacity and cycling stability of Li–S batteries. This work provides a useful strategy for realizing practical applications of high‐performance Li–S batteries.  相似文献   

17.
Lithium–sulfur (Li‐S) batteries are a promising next‐generation energy‐storage system, but the polysulfide shuttle and dendritic Li growth seriously hinder their commercial viability. Most of the previous studies have focused on only one of these two issues at a time. To address both the issues simultaneously, presented here is a highly conductive, noncarbon, 3D vanadium nitride (VN) nanowire array as an efficient host for both sulfur cathodes and lithium‐metal anodes. With fast electron and ion transport and high porosity and surface area, VN traps the soluble polysulfides, promotes the redox kinetics of sulfur cathodes, facilitates uniform nucleation/growth of lithium metal, and inhibits lithium dendrite growth at an unprecedented high current density of 10 mA cm?2 over 200 h of repeated plating/stripping. As a result, VN‐Li||VN‐S full cells constructed with VN as both an anode and cathode host with a negative to positive electrode capacity ratio of only ≈2 deliver remarkable electrochemical performance with a high Coulombic efficiency of ≈99.6% over 850 cycles at a high 4 C rate and a high areal capacity of 4.6 mA h cm?2. The strategy presented here offers a viable approach to realize high‐energy‐density, safe Li‐metal‐based batteries.  相似文献   

18.
Lithium–sulfur batteries are attractive for automobile and grid applications due to their high theoretical energy density and the abundance of sulfur. Despite the significant progress in cathode development, lithium metal degradation and the polysulfide shuttle remain two critical challenges in the practical application of Li–S batteries. Development of advanced electrolytes has become a promising strategy to simultaneously suppress lithium dendrite formation and prevent polysulfide dissolution. Here, a new class of concentrated siloxane‐based electrolytes, demonstrating significantly improved performance over the widely investigated ether‐based electrolytes are reported in terms of stabilizing the sulfur cathode and Li metal anode as well as minimizing flammability. Through a combination of experimental and computational investigation, it is found that siloxane solvents can effectively regulate a hidden solvation‐ion‐exchange process in the concentrated electrolytes that results from the interactions between cations/anions (e.g., Li+, TFSI?, and S2?) and solvents. As a result, it could invoke a quasi‐solid‐solid lithiation and enable reversible Li plating/stripping and robust solid‐electrolyte interphase chemistries. The solvation‐ion‐exchange process in the concentrated electrolytes is a key factor in understanding and designing electrolytes for other high‐energy lithium metal batteries.  相似文献   

19.
Rational design of effective polysulfide barriers is highly important for high‐performance lithium‐sulfur (Li‐S) batteries. A variety of adsorbents have been applied as interlayers to alleviate the shuttle effect. Nevertheless, the unsuccessful oxidation of Li2S on interlayers leads to loss of active materials and blocks Li ion transport. In this work, a MoN‐based interlayer sandwiched between the C‐S cathode and the separator is developed. Such an interlayer not only strongly binds lithium polysulfides via Mo‐S bonding but also efficiently accelerates the decomposition of Li2S. The acceleration mechanism toward Li2S decomposition is determined to be a combination of contributions of catalytic cleavage of Li‐S bond in Li2S based on the proposed covalence‐activation mechanism and rapid migration of the produced Li ions. As a result, the C–S cathodes with the as‐developed interlayer manifest a negligible charging potential barrier and outstanding cycling stability with a very low capacity fading rate of 0.023% per cycle during 1500 cycles at 1 C. High areal capacity of 6.02 mAh cm?2 is achieved for high sulfur loading of 7.0 mg cm?2 after cycling at 0.1 C. The material and strategy demonstrated in this work can open the door toward developing shuttle suppression interlayers without impairing cathode performance.  相似文献   

20.
Driven by increasing demand for high‐energy‐density batteries for consumer electronics and electric vehicles, substantial progress is achieved in the development of long‐life lithium–sulfur (Li–S) batteries. Less attention is given to Li–S batteries with high volume energy density, which is crucial for applications in compact space. Here, a series of elastic sandwich‐structured cathode materials consisting of alternating VS2‐attached reduced graphene oxide (rGO) sheets and active sulfur layers are reported. Due to the high polarity and conductivity of VS2, a small amount of VS2 can suppress the shuttle effect of polysulfides and improve the redox kinetics of sulfur species in the whole sulfur layer. Sandwich‐structured rGO–VS2/S composites exhibit significantly improved electrochemical performance, with high discharge capacities, low polarization, and excellent cycling stability compared with their bare rGO/S counterparts. Impressively, the tap density of rGO–VS2/S with 89 wt% sulfur loading is 1.84 g cm?3, which is almost three times higher than that of rGO/S with the same sulfur content (0.63 g cm?3), and the volumetric specific capacity of the whole cell is as high as 1182.1 mA h cm?3, comparable with the state‐of‐the‐art reported for energy storage devices, demonstrating the potential for application of these composites in long‐life and high‐energy‐density Li–S batteries.  相似文献   

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