Lithium-sulfur (Li-S) batteries have gained great attention due to the high theoretical energy density and low cost,yet their further commercialization has been obstructed by the notorious shuttle effect and sluggish ...Lithium-sulfur (Li-S) batteries have gained great attention due to the high theoretical energy density and low cost,yet their further commercialization has been obstructed by the notorious shuttle effect and sluggish redox dynamics.Herein,we supply a strategy to optimize the electron structure of Ni_(2)P by concurrently introducing B-doped atoms and P vacancies in Ni_(2)P (Vp-B-Ni_(2)P),thereby enhancing the bidirectional sulfur conversion.The study indicates that the simultaneous introduction of B-doped atoms and P vacancies in Ni_(2)P causes the redistribution of electron around Ni atoms,bringing about the upward shift of d-band center of Ni atoms and effective d-p orbital hybridization between Ni atoms and sulfur species,thus strengthening the chemical anchoring for lithium polysulfides (LiPSs) as well as expediting the bidirectional conversion kinetics of sulfur species.Meanwhile,theoretical calculations reveal that the incorporation of B-doped atoms and P vacancies in Ni_(2)P selectively promotes Li2S dissolution and nucleation processes.Thus,the Li-S batteries with Vp-B-Ni_(2)P-separators present outstanding rate ability of 777 m A h g^(-1)at 5 C and high areal capacity of 8.03 mA h cm^(-2)under E/S of 5μL mg^(-1)and sulfur loading of 7.20 mg cm^(-2).This work elucidates that introducing heteroatom and vacancy in metal phosphide collaboratively regulates the electron structure to accelerate bidirectional sulfur conversion.展开更多
Heterostructure engineering for sulfur hosts is an effective way to achieve interfacial synergistic effects on suppressing the“shuttle effect”of polysulfides and thus improve electrochemical performance of lithium–...Heterostructure engineering for sulfur hosts is an effective way to achieve interfacial synergistic effects on suppressing the“shuttle effect”of polysulfides and thus improve electrochemical performance of lithium–sulfur(Li–S)batteries.Rational selection and design of different components into heterostructures is vital to enhance the synergistic effect.Herein,MoS_(2)/MoP Mott–Schottky heterostructure nanoparticles decorated on reduced graphene oxide(MoS_(2)/MoP@rGO)are fabricated and used as sulfur host firstly.Theoretical calculation and experiment results reveal that the in-situ introduction of MoP could tune the electronic structure,activate the basal plane of MoS_(2),and achieve the interfacial synergistic effects between adsorption(MoS_(2))and fast conversion(MoP).Such synergistic effects enable MoS_(2)/MoP@rGO to not only remarkably facilitate Li_(2)S deposition during the discharging process but also significantly accelerate the Li_(2)S dissolution during the charging process,demonstrating bidirectional promotion behaviors.Thus,the designed cathode delivers initial capacity of 919.5 mA·h·g^(−1)with capacity of 502.3 mA·h·g^(−1)remaining after 700 cycles at 0.5 C.Even under higher sulfur loading of 4.31 mg·cm^(−2)and lower electrolyte to sulfur(E/S)ratio of 8.21μL·mg^(−1),the MoS_(2)/MoP@rGO@S cathode could still achieve good capacity and cycle stability.This work provides a novel and efficient structural design strategy of sulfur hosts for high-performance Li–S energy storage systems.展开更多
Modulating the electronic structure has emerged as an effective strategy for optimizing the adsorption and catalytic capabilities of electrocatalysts in lithium-sulfur(Li-S)batteries.However,the regulation of electron...Modulating the electronic structure has emerged as an effective strategy for optimizing the adsorption and catalytic capabilities of electrocatalysts in lithium-sulfur(Li-S)batteries.However,the regulation of electronic structure involving spin-related charge transfer and orbital interactions has been largely underexplored in sulfur electrocatalysts.Herein,selenium-deficient bimetallic selenides embedded in a coaxial carbon layer(CoSe_(2-x)/ZnSe)were meticulously fabricated as electrocatalysts,aiming to modulate the electron spin state of Co catalytic sites to enhance the bidirectional lithium polysulfides(LiPSs)conversion kinetics and suppress the LiPSs shuttling effect.Density functional theory(DFT)calculations and experimental results indicate that the selenium vacancies at the CoSe_(2-x)/ZnSe heterointerfaces weaken the ligand fields and drive the Co 3d orbital electronic structure transition from low-spin to high-spin states.Such tailored spin state configuration generates more unpaired electrons and upshifts the dband center,thus accelerating the charge transfer and strengthening the orbital interactions between LiPSs and Co catalytic sites.As a consequence,the assembled Li-S batteries with CoSe_(2-x)/ZnSe electrocatalysts exhibit an ultralow average decay rate of 0.028%per cycle at 1 C over 1000 cycles.This work presents a novel strategy for manipulating ligand fields to realize electron spin state modulation in sulfur electrocatalysts.展开更多
The introduction of materials with dual-functionalities,i.e.,the catalytic(adsorption)features to inhibit shuttle effects at the cathode side,and the capability to facilitate homogenous Li-ion fluxes at the anode side...The introduction of materials with dual-functionalities,i.e.,the catalytic(adsorption)features to inhibit shuttle effects at the cathode side,and the capability to facilitate homogenous Li-ion fluxes at the anode side,is a promising strategy to realize high performance lithium-sulfur batteries(LSBs).Herein,a facile and rational organic“ligand-induced”(trimesic acid(TMA))transformation tactic is proposed,which achieves the regulation of electronic performance and d-band center of bimetallic oxides(NiFe_(2)O_(4))to promote bidirectional sulfur conversion kinetics and stabilize the Li plating/striping during the charge/discharge process.The battery assembled with NiFe_(2)O_(4)-TMA modified separator exhibits a remarkable initial specific capacity of 1476.6 mAh·g^(-1)at 0.1 C,outstanding rate properties(661.1 mAh·g^(-1)at 8.0 C),and excellent cycling ability.The“ligand-induced”transformation tactic proposed in this work will open a whole new possibility for tuning the electronic structure and d-band center to enhance the performance of LSBs.展开更多
基金Institute of Technology Research Fund Program for Young Scholars21C Innovation Laboratory Contemporary Amperex Technology Co.,Limited,Ninde, 352100, China (21C–OP-202314)。
文摘Lithium-sulfur (Li-S) batteries have gained great attention due to the high theoretical energy density and low cost,yet their further commercialization has been obstructed by the notorious shuttle effect and sluggish redox dynamics.Herein,we supply a strategy to optimize the electron structure of Ni_(2)P by concurrently introducing B-doped atoms and P vacancies in Ni_(2)P (Vp-B-Ni_(2)P),thereby enhancing the bidirectional sulfur conversion.The study indicates that the simultaneous introduction of B-doped atoms and P vacancies in Ni_(2)P causes the redistribution of electron around Ni atoms,bringing about the upward shift of d-band center of Ni atoms and effective d-p orbital hybridization between Ni atoms and sulfur species,thus strengthening the chemical anchoring for lithium polysulfides (LiPSs) as well as expediting the bidirectional conversion kinetics of sulfur species.Meanwhile,theoretical calculations reveal that the incorporation of B-doped atoms and P vacancies in Ni_(2)P selectively promotes Li2S dissolution and nucleation processes.Thus,the Li-S batteries with Vp-B-Ni_(2)P-separators present outstanding rate ability of 777 m A h g^(-1)at 5 C and high areal capacity of 8.03 mA h cm^(-2)under E/S of 5μL mg^(-1)and sulfur loading of 7.20 mg cm^(-2).This work elucidates that introducing heteroatom and vacancy in metal phosphide collaboratively regulates the electron structure to accelerate bidirectional sulfur conversion.
基金supported by the National Natural Science Foundation of China(Grant Nos.51772060,51672059,52372041,52302087,51621091)Heilongjiang Touyan Team Program,and the Fundamental Research Funds for the Central Universities(Grant No.HIT.OCEF.2021003).
文摘Heterostructure engineering for sulfur hosts is an effective way to achieve interfacial synergistic effects on suppressing the“shuttle effect”of polysulfides and thus improve electrochemical performance of lithium–sulfur(Li–S)batteries.Rational selection and design of different components into heterostructures is vital to enhance the synergistic effect.Herein,MoS_(2)/MoP Mott–Schottky heterostructure nanoparticles decorated on reduced graphene oxide(MoS_(2)/MoP@rGO)are fabricated and used as sulfur host firstly.Theoretical calculation and experiment results reveal that the in-situ introduction of MoP could tune the electronic structure,activate the basal plane of MoS_(2),and achieve the interfacial synergistic effects between adsorption(MoS_(2))and fast conversion(MoP).Such synergistic effects enable MoS_(2)/MoP@rGO to not only remarkably facilitate Li_(2)S deposition during the discharging process but also significantly accelerate the Li_(2)S dissolution during the charging process,demonstrating bidirectional promotion behaviors.Thus,the designed cathode delivers initial capacity of 919.5 mA·h·g^(−1)with capacity of 502.3 mA·h·g^(−1)remaining after 700 cycles at 0.5 C.Even under higher sulfur loading of 4.31 mg·cm^(−2)and lower electrolyte to sulfur(E/S)ratio of 8.21μL·mg^(−1),the MoS_(2)/MoP@rGO@S cathode could still achieve good capacity and cycle stability.This work provides a novel and efficient structural design strategy of sulfur hosts for high-performance Li–S energy storage systems.
基金supported by the National Natural Science Foundation of China(No.52172214,52472220)。
文摘Modulating the electronic structure has emerged as an effective strategy for optimizing the adsorption and catalytic capabilities of electrocatalysts in lithium-sulfur(Li-S)batteries.However,the regulation of electronic structure involving spin-related charge transfer and orbital interactions has been largely underexplored in sulfur electrocatalysts.Herein,selenium-deficient bimetallic selenides embedded in a coaxial carbon layer(CoSe_(2-x)/ZnSe)were meticulously fabricated as electrocatalysts,aiming to modulate the electron spin state of Co catalytic sites to enhance the bidirectional lithium polysulfides(LiPSs)conversion kinetics and suppress the LiPSs shuttling effect.Density functional theory(DFT)calculations and experimental results indicate that the selenium vacancies at the CoSe_(2-x)/ZnSe heterointerfaces weaken the ligand fields and drive the Co 3d orbital electronic structure transition from low-spin to high-spin states.Such tailored spin state configuration generates more unpaired electrons and upshifts the dband center,thus accelerating the charge transfer and strengthening the orbital interactions between LiPSs and Co catalytic sites.As a consequence,the assembled Li-S batteries with CoSe_(2-x)/ZnSe electrocatalysts exhibit an ultralow average decay rate of 0.028%per cycle at 1 C over 1000 cycles.This work presents a novel strategy for manipulating ligand fields to realize electron spin state modulation in sulfur electrocatalysts.
基金This work was financially supported by the Natural Science Foundation of Guangdong Province(No.2019A1515011727)the Open Fund of the Guangdong Provincial Key Laboratory of Advance Energy Storage Materials.We also acknowledge the fund of Natural Science Foundation of Hubei Province(No.2021CFB011)the National Natural Science Foundation of China(Nos.52104309 and 52161033).
文摘The introduction of materials with dual-functionalities,i.e.,the catalytic(adsorption)features to inhibit shuttle effects at the cathode side,and the capability to facilitate homogenous Li-ion fluxes at the anode side,is a promising strategy to realize high performance lithium-sulfur batteries(LSBs).Herein,a facile and rational organic“ligand-induced”(trimesic acid(TMA))transformation tactic is proposed,which achieves the regulation of electronic performance and d-band center of bimetallic oxides(NiFe_(2)O_(4))to promote bidirectional sulfur conversion kinetics and stabilize the Li plating/striping during the charge/discharge process.The battery assembled with NiFe_(2)O_(4)-TMA modified separator exhibits a remarkable initial specific capacity of 1476.6 mAh·g^(-1)at 0.1 C,outstanding rate properties(661.1 mAh·g^(-1)at 8.0 C),and excellent cycling ability.The“ligand-induced”transformation tactic proposed in this work will open a whole new possibility for tuning the electronic structure and d-band center to enhance the performance of LSBs.
