Integrated host configuration of flexibly fibrous skeleton towards efficient polysulfide conversion and dendrite-free behavior in stable lithium-sulfur pouch cells

The commercialization of lithium-sulfur(Li-S) batteries is obstructed by the sluggish sulfur electrochemical reaction,severe polysulfide shuttling effect,and damaging dendritic lithium growth.Herein,a threedimensional(3D) conductive carbon nanofibers skeleton-based bifunctional electrode host material is fabricated,which consists of a two-dimensional(2D) ultra-thin NiSe_(2)-CoSe_(2)heterostructured nanosheet built on one-dimensional(1D) carbon nanofibers(NiSe_(2)-CoSe_(2)@CNF).When serving as cathodic host,the heterostructured NiSe_(2)-CoSe_(2)@CNF offers a synergistic function of polysulfide confinement and catalysis conversion.The S/NiSe_(2)-CoSe_(2)@CNF cathode shows outstanding cycling stability of 0.03% capacity decay rate per cycle over 500 cycles at 1 C.As anodic host,the NiSe_(2)-CoSe_(2)@CNF with high-flux Li+diffusion property and good lithiophilic capability realizes dendrite-free Li plating/stripping behavior.Benefiting from these synergistically merits,the Li-S full cell with S/NiSe_(2)-CoSe_(2)@CNFILi/NiSe_(2)-CoSe_(2)@CNF electrodes exhibits excellent electrochemical performance including a high specific capacity of1021 mA h g^(-1)over 100 cycles at 0.2 C and reversible areal capacity of 3.05 mA h cm^(-2)under a high sulfur loading of 4.33 mg cm^(-2)at 0.1 C.The pouch cell also delivers ultra-stable Li/S electrochemistry.This study demonstrates a rational and universal electrode construction strategy for developing practical and high-energy Li-S batteries.

Engineering Strategies for Suppressing the Shuttle Effect in Lithium–Sulfur Batteries

Lithium–sulfur(Li–S)batteries are supposed to be one of the most potential next-generation batteries owing to their high theoretical capacity and low cost.Nevertheless,the shuttle effect of firm multi-step two-electron reaction between sulfur and lithium in liquid electrolyte makes the capacity much smaller than the theoretical value.Many methods were proposed for inhibiting the shuttle effect of polysulfide,improving corresponding redox kinetics and enhancing the integral performance of Li–S batteries.Here,we will comprehensively and systematically summarize the strategies for inhibiting the shuttle effect from all components of Li–S batteries.First,the electrochemical principles/mechanism and origin of the shuttle effect are described in detail.Moreover,the efficient strategies,including boosting the sulfur conversion rate of sulfur,confining sulfur or lithium polysulfides(LPS)within cathode host,confining LPS in the shield layer,and preventing LPS from contacting the anode,will be discussed to suppress the shuttle effect.Then,recent advances in inhibition of shuttle effect in cathode,electrolyte,separator,and anode with the aforementioned strategies have been summarized to direct the further design of efficient materials for Li–S batteries.Finally,we present prospects for inhibition of the LPS shuttle and potential development directions in Li–S batteries.

Designing metal sulfide-based cathodes and separators for suppressing polysulfide shuttling in lithium-sulfur batteries

Lithium-sulfur(Li-S)batteries,known for their high energy density,are attracting extensive research interest as a promising next-generation energy storage technology.However,their widespread use has been hampered by certain issues,including the dissolution and migration of polysulfides,along with sluggish redox kinetics.Metal sulfides present a promising solution to these obstacles regarding their high electrical conductivity,strong chemical adsorption with polysulfides,and remarkable electrocatalytic capabilities for polysulfide conversion.In this review,the recent progress on the utilization of metal sulfide for suppressing polysulfide shuttling in Li-S batteries is systematically summarized,with a special focus on sulfur hosts and functional separators.The critical roles of metal sulfides in realizing high-performing Li-S batteries have been comprehensively discussed by correlating the materials’structure and electrochemical performances.Moreover,the remaining issues/challenges and future perspectives are highlighted.By offering a detailed understanding of the crucial roles of metal sulfides,this review dedicates to contributing valuable knowledge for the pursuit of high-efficiency Li-S batteries based on metal sulfides.

Catalyzing the polysulfide conversion for promoting lithium sulfur battery performances:A review

Lithium-sulfur batteries(LSBs)are being recognized as potential successor to ubiquitous LIBs in daily life due to their higher theoretical energy density and lower cost effectiveness.However,the development of the LSB is beset with some tenacious issues,mainly including the insulation nature of the S or Li_(2)S(the discharged product),the unavoidable dissolution of the reaction intermediate products(mainly as lithium polysulfides(LiPSs)),and the subsequent LiPSs shuttling across the separator,resulting in the continuous loss of active material,anode passivation,and low coulombic efficiency.Containment methods by introducing the high-electrical conductivity host are commonly used in improving the electrochemical performances of LSBs.However,such prevalent technologies are in the price of reduced energy density since they require more addition of amount of host materials.Adding trace of catalysts that catalyze the redox reaction between S/Li_(2)S and Li_(2)Sn(3<n≤8),shows ingenious design,which not only accelerates the conversion reaction between the solid S species and dissolved S species,alleviating the shuttle effect,but also expedites the electron transport thus reducing the polarization of the electrode.In this review,the redox reaction process during Li-S chemistry are firstly highlighted.Recent developed catalysts,including transitionmetal oxides,chalcogenides,phosphides,nitrides,and carbides/borides are then outlined to better understand the role of catalyst additives during the polysulfide conversion.Finally,the critical issues,challenges,and perspectives are discussed to demonstrate the potential development of LSBs.

Bimetallic Metal-Organic Framework with High-Adsorption Capacity toward Lithium Polysulfides for Lithium–sulfur Batteries

The practical application of Li-S batteries is largely impeded by the“shuttle effect”generated at the cathode which results in a short life cycle of the battery.To address this issue,this work discloses a bimetallic metal-organic framework(MOF)as a sulfur host material based on Al-MOF,commonly called(Al)MIL-53.To obtain a high-adsorption capacity to lithium polysulfides(Li_(2)S_(x),4≤x≤8),we present an effective strategy to incorporate sulfiphilic metal ion(Cu^(2+))with high-binding energy to Li_(2)S_(x) into the framework.Through a one-step hydrothermal method,Cu^(2+) is homogeneously dispersed in Al-MOF,producing a bimetallic Al/Cu-MOF as advanced cathode material.The macroscopic Li2S4 solution permeation test indicates that the Al/Cu-MOF has better adsorption capacity to lithium polysulfides than monometallic Al-MOF.The sulfur-transfusing process is executed via a melt-diffusion method to obtain the sulfur-containing Al/CuMOF(Al/Cu-MOF-S).The assembled Li-S batteries with Al/Cu-MOF-S yield improved cyclic performance,much better than that of monometallic AlMOF as sulfur host.It is shown that chemical immobilization is an effective method for polysulfide adsorption than physical confinement and the bimetallic Al/Cu-MOF,formed by incorporation of sulfiphilic Cu^(2+) into porous MOF,will provide a novel and powerful approach for efficient sulfur host materials.

3,3'-二硫代二丙酸作为锂硫电池功能电解质添加剂的研究

锂硫电池由于其高理论容量、高能量密度以及较低的原料价格,被认为是目前最具潜力的储能电池之一。但是在实际应用中,锂硫电池的发展受到充放电过程中的“穿梭效应”和低活性材料利用率等的限制。本文探究了一种新型电解质添加剂3,3′-二硫代二丙酸(DTPA)对锂硫电池电化学性能提高的影响机制。结果表明,DTPA添加剂能与分散在电解液中的多硫化物相互作用,促进长链多硫化物转化为Li2S2和Li2S,从而缓解长链多硫化物向阳极的穿梭行为,提高氧化还原动力学和活性物质的利用率。添加DTPA后,锂硫电池的电化学性能得到了提高,在0.5C下,使用了1.5 wt.%DTPA作为电解液添加剂的锂硫电池初始循环容量为1093.4 mA·h/g,经过250次循环后容量为714.8 mA·h/g。此外,含DTPA的电池具有更高的电化学稳定性,其在2C下相对于0.1C的容量保持率为57.5%。本文的研究结果证明,DTPA作为电解质添加剂对锂硫电池的性能提高具有显著效果,为减少多硫化物的穿梭效应以增加锂硫电池的容量提供了一种可行的解决方案。

锂硫电池正极复合材料研究进展

锂硫电池(LSBs)凭借其超高的能量密度,价格低廉,环境友好等优势,有望成为下一代高性能电化学储能器件。然而,目前锂硫电池在商业化应用的道路上还存在着许多挑战,例如硫正极材料导电性能差,多硫化物的穿梭效应以及充放电过程电池内部的体积膨胀等,均是限制锂硫电池实际应用的重要因素。文章总结了近年来锂硫电池正极材料的研究进展,包括碳/硫复合材料、负载金属的碳/硫复合材料以及导电聚合物/硫复合材料。最后,对锂硫电池未来的研究进行了展望。

锂硫电池硫基正极材料研究进展

锂硫电池由于具有高理论比能量密度(2600 Wh/kg)、高理论比能量(1675 mAh/g)、原料低廉、环境友好等优点,逐渐成为继锂离子电池之后的又一研究热点。正极作为组成电池的关键部件,由于穿梭效应所造成的电极腐蚀及多硫化物溶解等现象极大阻碍了锂硫电池的实用化进程。本文从硫基正极材料改性角度入手,介绍了近年来对于单质硫基复合材料及非溶解机制含硫正极材料的研究进展,包括碳/单质硫复合材料、金属氧化物/单质硫复合材料、硫化碳炔正极材料等。最后对硫基正极的未来发展方向进行了总结和展望。

N-MXene/S复合材料在锂硫电池中的研究

锂硫电池实际能量密度不高、硫导电性差及多硫化物的穿梭效应等缺陷影响其商业化应用。采用层状MXene(TiC)与CH_(4)N_(2)O、LiOH合成多层N-MXene(TiC)复合材料,并采用高温固相法与硫(S)复合作为锂硫电池正极材料。结果表明:N-TiC/S复合材料的比表面积增加,层与层的间隙增大,不仅活性物质硫的导电性提高,抑制多硫化物的穿梭效应;同时具有良好的电化学稳定性,100圈循环后放电比容量仍保持850 mAh/g,效率保持在95%以上。

Higher-order polysulfides induced thermal runaway for 1.0 Ah lithium sulfur pouch cells

Comprehensive analyses on thermal runaway mechanisms are critically vital to achieve the safe lithium-sulfur(Li-S)batteries.The reactions between dissolved higher-order polysulfides and Li metal were found to be the origins for the thermal runaway of 1.0 Ah cycled Li-S pouch cells.16-cycle pouch cell indicates high safety,heating from 30 to 300 ℃ without thermal runaway,while 16-cycle pouch cell with additional electrolyte undergoes severe thermal runaway at 147.9 ℃,demonstrating the key roles of the electrolyte on the thermal safety of batteries.On the contrary,thermal runaway does not occur for 45-cycle pouch cell despite the addition of the electrolyte.It is found that the higher-order polysulfides(Li_(2)S_(x) ≥ 6)are discovered in 16-cycle electrolyte while the sulfur species in 45-cycle electrolyte are Li_(2)S_(x) ≤ 4.In addition,strong exothermic reactions are discovered between cycled Li and dissolved higher-order polysulfide(Li_(2)S_(6) and Li_(2)S_(8))at 153.0 ℃,driving the thermal runaway of cycled Li-S pouch cells.This work uncovers the potential safety risks of Li-S batteries and negative roles of the polysulfide shuttle for Li-S batteries from the safety view.

Effects of Catalysis and Separator Functionalization on High-Energy Lithium–Sulfur Batteries:A Complete Review

Lithium–sulfur(Li-S)batteries have the advantages of high theoretical specific capacity(1675 mAh g^(−1)),rich sulfur resources,low production cost,and friendly environment,which makes it one of the most promising next-generation rechargeable energy storage devices.However,the“shuttle effect”of polysulfide results in the passivation of metal lithium anode,the decrease of battery capacity and coulombic efficiency,and the deterioration of cycle stability.To realize the commercialization of Li-S batteries,its serious“shuttle effect”needs to be suppress.The commercial separators are ineffective to suppress this effect because of its large pore size.Therefore,it is an effective strategy to modify the separator surface and introduce functional modified layer.In addition to the blocking strategy,the catalysis of polysulfide conversion reaction is also an important factor hindering the migration of polysulfides.In this review,the principles of separator modification,functionalization,and catalysis in Li-S batteries are reviewed.Furthermore,the research trend of separator functionalization and polysulfide catalysis in the future is prospected.

Promoting polysulfide conversions via cobalt single-atom catalyst for fast and durable lithium-sulfur batteries

Although promising strategies have been developed to resolve the critical drawbacks of lithium-sulfur(Li-S)batteries,the intractable issues including undesirable shuttling of polysulfides and sluggish redox reaction kinetics have still been unresolved thoroughly.Herein,a cobalt single-atom(CoSA)catalyst comprising of atomic Co distributed homogeneously within nitrogen(N)-doped porous carbon(Co-NPC)nanosphere is constructed and utilized as a separator coating in Li-S batteries.The Co-NPC exposes abundant active sites participating in sulfur redox reactions,and remarkable catalytic activity boosting the rapid polysulfide conversions.As a result,Li-S batteries with Co-NPC coating layer realize significantly enhanced specific capacity(1295 mAh·g^(-1)at 0.2 C),rate capability(753 mAh·g^(-1)at 3.0 C),and long-life cyclic stability(601 mAh·g^(-1)after 500 cycles at 1.0 C).Increasing the areal sulfur loading to 6.2 mg·cm^(-2),an extremely high areal capacity of 7.92 mAh·cm^(-2)is achieved.Further in situ X-ray diffraction,density functional theory calculations,and secondary ion mass spectrometry confirm the high catalytic capability of CoSA towards reversible polysulfide conversion.This study supplies new insights for adopting single-atom catalyst to upgrade the electrochemical performance of Li-S batteries.

二维蒙脱土-碳纳米管交联多孔网络中间层对多硫化物穿梭的抑制作用

将一维碳纳米管(CNT)和二维蒙脱土(MMT)纳米片复合并用于修饰商用聚丙烯(PP)隔膜。得益于碳纳米管的高电子导电性,以及MMT对多硫化物(LiPS)的强吸附能力和低的锂离子传输势垒,所得的交联多孔CNT-MMT复合阻挡层具有优异的结构稳定性和高的锂离子传输能力,表现出抑制LiPS穿梭的性能,因此实现了高硫利用率。结果表明,该复合阻挡层修饰的PP隔膜有效提升了锂硫电池的锂离子扩散系数、放电比容量和循环稳定性。所组装锂硫电池的0.1 C初始放电比容量为1373 mAh g^(-1),且具有良好的循环稳定性,在1 C下经500次循环后其每圈容量衰减率仅为0.062%。

Oxygen-modulated metal nitride clusters with moderate binding ability to insoluble Li_(2)S_(x) for reversible polysulfide electrocatalysis

Multiphase sulfur redox reactions with advanced homogeneous and heterogeneous electrochemical processes in lithium–sulfur(Li–S)batteries possess sluggish kinetics.The slow kinetics leads to significant capacity decay during charge/discharge processes.Therefore,electrocatalysts with adequate sulfurredox properties are required to accelerate reversible polysulfide conversion in cathodes.In this study,we have fabricated an oxygen-modulated metal nitride cluster(C-MoN_(x)-O)that has a moderate binding ability to the insoluble Li_(2)S_(x)for reversible polysulfide electrocatalysis.A Li–S battery equipped with CMoN_(x)-O electrocatalyst displayed a high discharge capacity of 875 mAh g^(-1)at 0.5 C.The capacity decay rate of each cycle was only 0.10%after 280 cycles,which is much lower than the control groups(C-MoO_(x):0.16%;C-MoN_(x):0.21%).Kinetic studies and theoretical calculations suggest that C-MoN_(x)-O electrocatalyst presents a moderate binding ability to the insoluble Li_(2)S_(2)and Li_(2)S when compared to the C-MoO_(x)and C-MoN_(x)surfaces.Thus,the C-MoN_(x)-O can effectively immobilize and reversibly catalyze the solid–solid conversion of Li_(2)S_(2)–Li_(2)S during charge–discharge cycling,thus promoting reaction kinetics and eliminating the shuttle effect.This study to design oxygen-doped metal nitrides provides innovative structures and reversible solid–solid conversions to overcome the sluggish redox chemistry of polysulfides.

碳化钛类MXene基材料在锂硫电池中的应用研究进展

作为储能器件的重要一员,锂硫电池具有理论能量密度高、安全性好、成本低等优点,已成为目前最具前景的电源体系之一.但锂硫电池充放电过程中多硫化物的穿梭效应使其在长期循环过程中的性能衰减.MXene基材料具有优异的导电性和高比表面积,对多硫化锂具有强化学吸附和催化转化能力,能够有效避免多硫化物的穿梭效应,从而提高锂硫电池的循环稳定性和倍率性能.本工作简述了MXene基材料在锂硫电池中的应用优势,总结了MXene基复合材料在锂硫电池正极和隔膜中的应用研究现状,归纳了MXene基材料对锂硫电池穿梭效应的影响,最后,展望了MXene基材料在锂硫电池领域的未来研究方向.

O-NiCo_(2)S_(4)/CNT复合材料对多硫化锂催化转化性能研究

NiCo_(2)S_(4)由于具有丰富的催化位点和金属特性,能够催化锂硫电池中的多硫化锂的氧化还原转化。然而,其催化活性和化学吸附性不足以抑制多硫化锂在长循环中的穿梭效应。通过水热法结合空气煅烧制备了氧掺杂NiCo_(2)S_(4)/CNT复合材料(O-NiCo_(2)S_(4)/CNT),系统的实验证明氧掺杂后体相NiCo_(2)S_(4)的结晶度增强,表面NiCo_(2)S_(4)趋于无定形态,O-NiCo_(2)S_(4)/CNT的电导率升高。其次,O掺杂可以有效调节NiCo_(2)S_(4)中金属阳离子的电子结构,增强催化活性位点的化学吸附和催化转化能力,进而提升多硫化锂的转化动力学,抑制多硫化锂的穿梭效应。基于O-NiCo_(2)S_(4)/CNT功能化隔膜的锂硫电池在0.2 C下初始放电容量高达1362.7 mAh/g,循环150圈后的容量为923 mAh/g,每圈的容量衰减率仅为0.21%。在3 C下,容量可达到701.8 mAh/g。本工作表明,氧原子掺杂金属硫化物是开发高效催化剂的一种有效策略。

锂硫电池电解液功能性添加剂研究进展

由于具有能量密度高、成本低等优点,锂硫电池成为最有前景的下一代电池体系之一。然而,锂硫电池的实际应用仍面临着严峻挑战,如硫和硫化锂的低电导率、多硫化物的穿梭效应和锂枝晶的生长等。通过电解液的优化,可以改善电极Ⅰ电解质界面,减弱副反应,提高电池性能。其中,电解液中的功能添加剂能有效调节电极界面和电池的氧化还原机制。本文系统性总结了锂硫电池添加剂的最新研究进展,并根据添加剂对锂金属负极的保护作用和对硫正极的稳定作用进行了分类。另外,本文详细讨论了添加剂在硫正极的作用,如抑制多硫化物的溶解和穿梭、充当氧化还原介质、激活硫化锂的沉积与溶解等。最后,本文展望了锂硫电池添加剂的发展前景,希望能对高性能锂硫电池电解液的设计提供借鉴。

多活性中心双金属硫化物促进多硫化锂转化构建高性能锂硫电池

锂硫电池是极具应用潜力的下一代高能量密度电池体系之一。然而,其充放电中间产物多硫化锂的“穿梭效应”不仅消耗大量电解液,还导致硫活性物质利用率低、循环寿命短,是锂硫电池产业化进程中的主要瓶颈之一。引入催化剂加速硫活性物质转化速率,减少多硫化锂在电解液中的累积浓度,是抑制穿梭效应的有效解决策略。高效的催化剂应具备丰富的催化活性位点,以确保高效吸附多硫化锂并加速其向不溶的充放电产物转化。本文制备出硫掺杂石墨烯表面原位负载的双金属硫化物NiCo_(2)S_(4)(NCS@SG)并将其作为催化剂应用于锂硫电池的中间层。相比于单金属硫化物(CoS),NiCo_(2)S_(4)催化剂具有多活性中心催化位点,可以更好地吸附多硫化锂并促进其向放电产物快速转化。应用上述中间层后,电池的充放电比容量、库仑效率和循环稳定性得到了明显提升。当硫的负载达到15.3 mg.cm^(-2)时,经过50次循环后,具有NCS@SG中间层的电池获得了高达93.9%的容量保持率。上述结果表明,设计双金属基催化剂是优化锂硫电池催化剂活性和反应效率的重要方向。

SnS_(2)/ZIF-8衍生二维多孔氮掺杂碳纳米片复合材料的锂硫电池性能研究

锂硫电池(LSBs)因能量密度高、原料储量丰富、环境友好等优点引起了广泛关注。然而,多硫化物的穿梭效应、反应过程中较大的体积膨胀以及硫较差的电子电导率等缺点极大地限制了其发展。本研究设计了一种SnS_(2)纳米颗粒与ZIF-8衍生的花状二维多孔碳纳米片/硫复合材料(ZCN-SnS_(2)-S),并研究了其作为锂硫电池正极的电化学性能。其独特的二维花状多孔结构不仅有效缓解了反应过程中的体积膨胀,而且为Li+和电子的传输提供了快速通道,杂原子N也促进了对多硫化物的吸附作用。并且负载的极性SnS_(2)纳米颗粒极大地增强了对多硫化物的吸附,从而使ZCN-SnS_(2)-S复合材料表现出优异的电化学性能。在0.2C(1C=1675 mA·g^(–1))电流密度下,ZCN-SnS_(2)-S电极循环100次后仍能保持948 mAh·g^(–1)的高可逆比容量,容量保持率为83.7%。即使在2C的高电流密度下循环300圈,ZCN-SnS_(2)-S电极仍具有546 mAh·g^(–1)的可逆比容量。

Theoretical kinetic quantitative calculation predicted the expedited polysulfides degradation

The performance of lithium-sulfur battery is restricted by the lower value of electrode conductance and the sluggish LiPSs degradation kinetics.Unfortunately,the degradation rate of polysulfides was mostly attributed to the catalytic energy barrier in previous,which is unable to give accurate predictions on the performance of lithium-sulfur battery.Thereby,a quantitative framework relating the battery performance to catalytic energy barrier and electrical conductivity of the cathode host is developed here to quantitate the tendency.As the model compound,calculated-Ti_(4)O_(7)(c-Ti_(4)O_(7))has the highest comprehensive index with excellent electrical conductivity,although the catalytic energy barrier is not ideal.Through inputting the experimental properties such as impedance and charge/discharge data into the as-build model,the final conclusion is still in line with our prediction that Ti_(4)O_(7)host shows the most excellent electrochemical performance.Therefore,the accurate model here would be attainable to design lithium-sulfur cathode materials with a bottom–up manner.