With high energy density and low material cost,lithium sulfur batteries(LSBs)emerge quite expeditiously as a fascinating energy storage system over the past decade.Broad applications of LSBs ranging from electric vehi...With high energy density and low material cost,lithium sulfur batteries(LSBs)emerge quite expeditiously as a fascinating energy storage system over the past decade.Broad applications of LSBs ranging from electric vehicles to stationary grid storage seem rather bright in recent literatures.However,there still exist many pressing challenges to be addressed because we do not yet fully understand and control the electrode-electrolyte interface chemistries during battery operation,such as polysulide shuttling and poor utilization of active sulfur.Single-atom catalysts(SACs)pave new possibilities of tackling the tough issues due to their decent applicability in the atomic-level identification of structure-activity relationships and reaction mechanism,as well as their structural tunability with atomic precision.This review comprehensively summarizes the very recent advances in utilization of highly active SACs for LSBs by stating and discussing the related publications,which involves catalyst synthesis routes,battery pertormance,catalytic mechanisms,optimization strategies,and promises to achieve long-lite,high-energy LSBs.We see that endeavors to employ SACs to modify sulfur cathode have allowed efficient polysulfide conversion and confinement,leading to the minimization of shuttle effect.Parallel efforts are being devoted to extending the scope of SACs to cell separator and lithium metal anode in order to unlock the full potential of LSBs.We also obtain mechanistic insights into battery chemistries and nature of SACs in their strong interactions with polysulfides through advanced in situ characterizations documented.Overall,acceleration in the development of LSBs by introducing SACs is noticeable,and this cutting edge needs more attentions to further promoting the design of better LSBs.展开更多
Lithium–sulfur(Li–S)batteries have extremely high theoretical energy density that make them as promising systems toward vast practical applications.Expediting redox kinetics of sulfur species is a decisive task to b...Lithium–sulfur(Li–S)batteries have extremely high theoretical energy density that make them as promising systems toward vast practical applications.Expediting redox kinetics of sulfur species is a decisive task to break the kinetic limitation of insulating lithium sulfide/disulfide precipitation/dissolution.Herein,we proposed a porphyrinderived atomic electrocatalyst to exert atomic-efficient electrocatalytic effects on polysulfide intermediates.Quantifying electrocatalytic efficiency of liquid/solid conversion through a potentiostatic intermittent titration technique measurement presents a kinetic understanding of specific phase evolutions imparted by the atomic electrocatalyst.Benefiting from atomically dispersed“lithiophilic”and“sulfiphilic”sites on conductive substrates,the finely designed atomic electrocatalyst endows Li–S cells with remarkable cycling stablity(cyclic decay rate of 0.10%in 300 cycles),excellent rate capability(1035 mAh g−1 at 2 C),and impressive areal capacity(10.9 mAh cm−2 at a sulfur loading of 11.3 mg cm−2).The present work expands atomic electrocatalysts to the Li–S chemistry,deepens kinetic understanding of sulfur species evolution,and encourages application of emerging electrocatalysis in other multielectron/multiphase reaction energy systems.展开更多
Electrochemical behavior of aqueous sodium sulfide solution at graphite anode,under the condition of different concentrations of Na2S and different temperatures,has been investigated by cyclic voltammetry and chronopo...Electrochemical behavior of aqueous sodium sulfide solution at graphite anode,under the condition of different concentrations of Na2S and different temperatures,has been investigated by cyclic voltammetry and chronopotentiometry.The results show that the anodic oxidation of aqueous sulfide solution is irreversible and that polysulfides are formed in rate-determining step of the anodic oxidation.With the increase of electrolytic temperature,potentials corresponding to anodic peaks shift to more negative and those corresponding to cathodic peaks shift to more positive,which indicates that the elevating of temperature is favorable to both oxidation of the sulfide and reduction of products polysulfides or elemental sulfur.Rate constants ks of standard electrode reaction for anodic oxidation of Na2S solution are between 10-4.08～10-4.35cm·s-1 at 70℃.Chronopotentiometric studies show two potential peaks in time-potential curve for a smaller current density value.The potential peaks may result from a self-catalytic effect taking place due to both dissolution of elemental sulfur by S2-,HS-and Sx2-,and transition reactions among polysulfides.The potential peaks disappear with the increasing of anodic current density.展开更多
Lithium–sulfur(Li–S)batteries have been recognized as promising substitutes for current energy-storage technologies owing to their exceptional advantages in very high-energy density and excellent material sustainabi...Lithium–sulfur(Li–S)batteries have been recognized as promising substitutes for current energy-storage technologies owing to their exceptional advantages in very high-energy density and excellent material sustainability.The cathode with high sulfur areal loading is vital for the practical applications of Li–S batteries with very high energy density.However,the high sulfur loading in an electrode results in poor rate and cycling performances of batteries in most cases.Herein,we used diameters of 5.0(D5)and 13.0(D13)mm to probe the effect of electrodes with different sizes on the rate and cycling performances under a high sulfur loading(4.5 mg cm^-2).The cell with D5 sulfur cathode exhibits better rate and cycling performances comparing with a large(D13)cathode.Both the high concentration of lithium polysulfides and corrosion of lithium metal anode impede rapid kinetics of sulfur redox reactions,which results in inferior battery performance of the Li–S cell with large diameter cathode.This work highlights the importance of rational matching of the large sulfur cathode with a high areal sulfur loading,carbon modified separators,organic electrolyte,and Li metal anode in a pouch cell,wherein the sulfur redox kinetics and lithium metal protection should be carefully considered under the flooded lithium polysulfide conditions in a working Li–S battery.展开更多
Lithium/sulfur （Li/S） cells have great potential to become mainstream secondary batteries due to their ultra-high theoretical specific energy. The major challenge for Li/S cells is the unstable cycling performance c...Lithium/sulfur （Li/S） cells have great potential to become mainstream secondary batteries due to their ultra-high theoretical specific energy. The major challenge for Li/S cells is the unstable cycling performance caused by the sulfur＇s insulating nature and the high-solubility of the intermediate polysulfide products. Several years of efforts to develop various fancy carbon nanostructures, trying to physically encapsulate the polysulfides, did not yet push the cell＇s cycle life long enough to compete with current Li ion cells. The focus of this review is on the recent progress in chemical bonding strategy for trapping polysulfides through employing functional groups and additives in carbon matrix. Research results on understanding the working mechanism of chemical interaction between polysulfides and functional groups （e.g. 0-, B-, N- and S-） in carbon matrix, metal-based additives, or polymer additives during charge/discharge are discussed.展开更多
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 o...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.展开更多
Lithium-sulfur batteries are promising electrochemical energy storage devices because of their high theoretical specific capacity and energy density. An ideal sulfur host should possess high conductivity and embrace t...Lithium-sulfur batteries are promising electrochemical energy storage devices because of their high theoretical specific capacity and energy density. An ideal sulfur host should possess high conductivity and embrace the physical confinement or strong chemisorption to dramatically suppress the polysulfide dissolution. Herein, uniform TiN hollow nanospheres with an average diameter of N 160 nm have been reported as highly efficient lithium polysulfide reservoirs for high-performance lithium-sulfur batteries. Combining the high conductivity and chemical trapping of lithium polysulfides, the obtained S/TiN cathode of 70 wt.% sulfur content in the composite delivered an excellent long-life cycling performance at 0.5C and 1.0C over 300 cycles. More importantly, a stable capacity of 710.4 mAh.g-1 could be maintained even after 100 cydes at 0.2C with a high sulfur loading of 3.6 mg-cm-1 The nature of the interactions between TiN and lithium polysulfide species was investigated by X-ray photoelectron spectroscopy studies. Theoretical calculations were also carried out and the results revealed a strong binding between TiN and the lithium polysulfide species. It is expected that this dass of conductive and polar materials would pave a new way for the high-energy lithium-sulfur batteries in the future.展开更多
Despite promising characteristics such as high specific energy and low cost,current Li-S batteries fall short in cycle life.Improving the cycling stability of S cathodes requires immobilizing the lithium polysulfide ...Despite promising characteristics such as high specific energy and low cost,current Li-S batteries fall short in cycle life.Improving the cycling stability of S cathodes requires immobilizing the lithium polysulfide （LPS） intermediates as well as accelerating their redox kinetics.Although many materials have been explored for trapping LPS,the ability to promote LPS redox has attracted much less attention.Here,we report for the first time on transition metal phosphides as effective host materials to enhance both LPS adsorption and redox.Integrating MoP-nanoparticle-decorated carbon nanotubes with S deposited on graphene oxide,we enable Li-S battery cathodes with substantially improved cycling stability and rate capability.Capacity decay rates as low as 0.017% per cycle over 1,000 cycles can be realized.Stable and high areal capacity （〉 3 mAh＆#183;cm-2） can be achieved under high mass loading conditions.Comparable electrochemical performance can also be achieved with analogous material structures based on CoP,demonstrating the potential of metal phosphides for long-cycle Li-S batteries.展开更多
The exploitation of new sulfiphilic and catalytic materials is considered as the promising strategy to overcome severe shuttle effect and sluggish kinetics conversion of lithium polysulfides within lithium-sulfur batt...The exploitation of new sulfiphilic and catalytic materials is considered as the promising strategy to overcome severe shuttle effect and sluggish kinetics conversion of lithium polysulfides within lithium-sulfur batteries.Herein,we design and fabricate monodisperse VN ultrafine nanocrystals immobilized on nitrogen-doped carbon hybrid nanosheets(VN@NCSs)via an one-step in-situ selftemplate and self-reduction strategy,which simultaneously promotes the interaction with polysulfides and the kinetics of the sulfur conversion reactions demonstrated by experimental and theoretical results.By virtue of the multifunctional structural features of VN@NCSs,the cell with ultrathin VN@NCSs(only 5 pm thickness)modified separator indicates improved electrochemical performances with long cycling stability over 1,000 cycles at 2 C with only 0.041%capacity decay per cycle and excellent rate capability(787.6 mAh g^(-1) at 10 C).Importantly,it delivers an areal reversible capacity of 3.71 mAh cm^(-2) accompanied by robust cycling life.展开更多
Lithium–sulfur batteries with an ultrahigh theoretical energy density of 2600 Wh kg^(−1) are highly consid-ered as desirable next-generation energy storage devices that will meet the growing demand of energy consumpt...Lithium–sulfur batteries with an ultrahigh theoretical energy density of 2600 Wh kg^(−1) are highly consid-ered as desirable next-generation energy storage devices that will meet the growing demand of energy consumption worldwide.However,complicated sul-fur redox reactions and polysulfide shuttling signifi-cantly postpone the applications of lithium-sulfur batteries with rapid capacity decay and low Coulom-bic efficiency.展开更多
基金the National Key R&D Program of China(No.2018YFA0702003)the National Natural Science Foundation of China(Nos.21890383,21671117,21871159)+1 种基金the China Postdoctoral Science Foundation(No.2019M660607)Z.C.Z.acknowledges support from the Shuimu Isinghua Scholar Program.
文摘With high energy density and low material cost,lithium sulfur batteries(LSBs)emerge quite expeditiously as a fascinating energy storage system over the past decade.Broad applications of LSBs ranging from electric vehicles to stationary grid storage seem rather bright in recent literatures.However,there still exist many pressing challenges to be addressed because we do not yet fully understand and control the electrode-electrolyte interface chemistries during battery operation,such as polysulide shuttling and poor utilization of active sulfur.Single-atom catalysts(SACs)pave new possibilities of tackling the tough issues due to their decent applicability in the atomic-level identification of structure-activity relationships and reaction mechanism,as well as their structural tunability with atomic precision.This review comprehensively summarizes the very recent advances in utilization of highly active SACs for LSBs by stating and discussing the related publications,which involves catalyst synthesis routes,battery pertormance,catalytic mechanisms,optimization strategies,and promises to achieve long-lite,high-energy LSBs.We see that endeavors to employ SACs to modify sulfur cathode have allowed efficient polysulfide conversion and confinement,leading to the minimization of shuttle effect.Parallel efforts are being devoted to extending the scope of SACs to cell separator and lithium metal anode in order to unlock the full potential of LSBs.We also obtain mechanistic insights into battery chemistries and nature of SACs in their strong interactions with polysulfides through advanced in situ characterizations documented.Overall,acceleration in the development of LSBs by introducing SACs is noticeable,and this cutting edge needs more attentions to further promoting the design of better LSBs.
基金This work was supported by the National Key Research and Development Program(2016YFA0202500)National Natural Science Foundation of China(21776019,21808124,and U1801257)We thank Jin Xie and Meng Zhao for their helpful discussion.
文摘Lithium–sulfur(Li–S)batteries have extremely high theoretical energy density that make them as promising systems toward vast practical applications.Expediting redox kinetics of sulfur species is a decisive task to break the kinetic limitation of insulating lithium sulfide/disulfide precipitation/dissolution.Herein,we proposed a porphyrinderived atomic electrocatalyst to exert atomic-efficient electrocatalytic effects on polysulfide intermediates.Quantifying electrocatalytic efficiency of liquid/solid conversion through a potentiostatic intermittent titration technique measurement presents a kinetic understanding of specific phase evolutions imparted by the atomic electrocatalyst.Benefiting from atomically dispersed“lithiophilic”and“sulfiphilic”sites on conductive substrates,the finely designed atomic electrocatalyst endows Li–S cells with remarkable cycling stablity(cyclic decay rate of 0.10%in 300 cycles),excellent rate capability(1035 mAh g−1 at 2 C),and impressive areal capacity(10.9 mAh cm−2 at a sulfur loading of 11.3 mg cm−2).The present work expands atomic electrocatalysts to the Li–S chemistry,deepens kinetic understanding of sulfur species evolution,and encourages application of emerging electrocatalysis in other multielectron/multiphase reaction energy systems.
文摘Electrochemical behavior of aqueous sodium sulfide solution at graphite anode,under the condition of different concentrations of Na2S and different temperatures,has been investigated by cyclic voltammetry and chronopotentiometry.The results show that the anodic oxidation of aqueous sulfide solution is irreversible and that polysulfides are formed in rate-determining step of the anodic oxidation.With the increase of electrolytic temperature,potentials corresponding to anodic peaks shift to more negative and those corresponding to cathodic peaks shift to more positive,which indicates that the elevating of temperature is favorable to both oxidation of the sulfide and reduction of products polysulfides or elemental sulfur.Rate constants ks of standard electrode reaction for anodic oxidation of Na2S solution are between 10-4.08～10-4.35cm·s-1 at 70℃.Chronopotentiometric studies show two potential peaks in time-potential curve for a smaller current density value.The potential peaks may result from a self-catalytic effect taking place due to both dissolution of elemental sulfur by S2-,HS-and Sx2-,and transition reactions among polysulfides.The potential peaks disappear with the increasing of anodic current density.
基金supported by the National Key Research and Development Program(2016YFA0202500 and 2016YFA0200102)the National Natural Science Foundation of China(21776019,21805162,51772069,and U1801257)+1 种基金China Postdoctoral Science Foundation(2018M630165)Beijing Key Research and Development Plan(Z181100004518001)
文摘Lithium–sulfur(Li–S)batteries have been recognized as promising substitutes for current energy-storage technologies owing to their exceptional advantages in very high-energy density and excellent material sustainability.The cathode with high sulfur areal loading is vital for the practical applications of Li–S batteries with very high energy density.However,the high sulfur loading in an electrode results in poor rate and cycling performances of batteries in most cases.Herein,we used diameters of 5.0(D5)and 13.0(D13)mm to probe the effect of electrodes with different sizes on the rate and cycling performances under a high sulfur loading(4.5 mg cm^-2).The cell with D5 sulfur cathode exhibits better rate and cycling performances comparing with a large(D13)cathode.Both the high concentration of lithium polysulfides and corrosion of lithium metal anode impede rapid kinetics of sulfur redox reactions,which results in inferior battery performance of the Li–S cell with large diameter cathode.This work highlights the importance of rational matching of the large sulfur cathode with a high areal sulfur loading,carbon modified separators,organic electrolyte,and Li metal anode in a pouch cell,wherein the sulfur redox kinetics and lithium metal protection should be carefully considered under the flooded lithium polysulfide conditions in a working Li–S battery.
文摘Lithium/sulfur （Li/S） cells have great potential to become mainstream secondary batteries due to their ultra-high theoretical specific energy. The major challenge for Li/S cells is the unstable cycling performance caused by the sulfur＇s insulating nature and the high-solubility of the intermediate polysulfide products. Several years of efforts to develop various fancy carbon nanostructures, trying to physically encapsulate the polysulfides, did not yet push the cell＇s cycle life long enough to compete with current Li ion cells. The focus of this review is on the recent progress in chemical bonding strategy for trapping polysulfides through employing functional groups and additives in carbon matrix. Research results on understanding the working mechanism of chemical interaction between polysulfides and functional groups （e.g. 0-, B-, N- and S-） in carbon matrix, metal-based additives, or polymer additives during charge/discharge are discussed.
基金supported by the National Key Research and Development Program(grant No.2021YFB2500300)National Natural Science Foundation of China(grant Nos.22179070,22075029,U1932220)+2 种基金Beijing Municipal Natural Science Foundation(grant No.Z200011)the Natural Science Foundation of Jiangsu Province(grant No.BK20220073)the Fundamental Research Funds for the Central Universities(grant No.2242022R10082).
文摘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.
文摘Lithium-sulfur batteries are promising electrochemical energy storage devices because of their high theoretical specific capacity and energy density. An ideal sulfur host should possess high conductivity and embrace the physical confinement or strong chemisorption to dramatically suppress the polysulfide dissolution. Herein, uniform TiN hollow nanospheres with an average diameter of N 160 nm have been reported as highly efficient lithium polysulfide reservoirs for high-performance lithium-sulfur batteries. Combining the high conductivity and chemical trapping of lithium polysulfides, the obtained S/TiN cathode of 70 wt.% sulfur content in the composite delivered an excellent long-life cycling performance at 0.5C and 1.0C over 300 cycles. More importantly, a stable capacity of 710.4 mAh.g-1 could be maintained even after 100 cydes at 0.2C with a high sulfur loading of 3.6 mg-cm-1 The nature of the interactions between TiN and lithium polysulfide species was investigated by X-ray photoelectron spectroscopy studies. Theoretical calculations were also carried out and the results revealed a strong binding between TiN and the lithium polysulfide species. It is expected that this dass of conductive and polar materials would pave a new way for the high-energy lithium-sulfur batteries in the future.
文摘Despite promising characteristics such as high specific energy and low cost,current Li-S batteries fall short in cycle life.Improving the cycling stability of S cathodes requires immobilizing the lithium polysulfide （LPS） intermediates as well as accelerating their redox kinetics.Although many materials have been explored for trapping LPS,the ability to promote LPS redox has attracted much less attention.Here,we report for the first time on transition metal phosphides as effective host materials to enhance both LPS adsorption and redox.Integrating MoP-nanoparticle-decorated carbon nanotubes with S deposited on graphene oxide,we enable Li-S battery cathodes with substantially improved cycling stability and rate capability.Capacity decay rates as low as 0.017% per cycle over 1,000 cycles can be realized.Stable and high areal capacity （〉 3 mAh＆#183;cm-2） can be achieved under high mass loading conditions.Comparable electrochemical performance can also be achieved with analogous material structures based on CoP,demonstrating the potential of metal phosphides for long-cycle Li-S batteries.
基金supports provided by the National Natural Science Foundation of China(Nos.21971145,21871164 and U1764258)the Taishan Scholar Project Foundation of Shandong Province(No.ts20190908)+1 种基金the Natural Science Foundation of Shandong Province(No.ZR2019MB024)Young Scholars Program of Shandong University(No.2017WLJH15).
文摘The exploitation of new sulfiphilic and catalytic materials is considered as the promising strategy to overcome severe shuttle effect and sluggish kinetics conversion of lithium polysulfides within lithium-sulfur batteries.Herein,we design and fabricate monodisperse VN ultrafine nanocrystals immobilized on nitrogen-doped carbon hybrid nanosheets(VN@NCSs)via an one-step in-situ selftemplate and self-reduction strategy,which simultaneously promotes the interaction with polysulfides and the kinetics of the sulfur conversion reactions demonstrated by experimental and theoretical results.By virtue of the multifunctional structural features of VN@NCSs,the cell with ultrathin VN@NCSs(only 5 pm thickness)modified separator indicates improved electrochemical performances with long cycling stability over 1,000 cycles at 2 C with only 0.041%capacity decay per cycle and excellent rate capability(787.6 mAh g^(-1) at 10 C).Importantly,it delivers an areal reversible capacity of 3.71 mAh cm^(-2) accompanied by robust cycling life.
基金This work was supported by National Key Re-search and Development Program(2016YFA0202500,2015CB932500,and2016YFA0200102)National Natural Scientific Foundation of China(21676160 and 21825501)Tsinghua University Initiative Scientific Research Program.
文摘Lithium–sulfur batteries with an ultrahigh theoretical energy density of 2600 Wh kg^(−1) are highly consid-ered as desirable next-generation energy storage devices that will meet the growing demand of energy consumption worldwide.However,complicated sul-fur redox reactions and polysulfide shuttling signifi-cantly postpone the applications of lithium-sulfur batteries with rapid capacity decay and low Coulom-bic efficiency.
