The swelling behavior and stability in solid electrolyte interphase(SEI)have been proved to determine the battery cycle life.A high swollen,unstable SEI shows a high permeability to electrolyte,which results in the ra...The swelling behavior and stability in solid electrolyte interphase(SEI)have been proved to determine the battery cycle life.A high swollen,unstable SEI shows a high permeability to electrolyte,which results in the rapid battery performance degradation.Here,we customize two SEIs with different spatial structures(bilayer and mosaic)by simply regulating the proportion of additive fluoroethylene carbonate.Surprisingly,due to the uniform distribution of dense inorganic nano-crystals in the inner,the bilayer SEI exhibits low-swelling and excellent mechanical properties,so the undesirable side reactions of the electrolyte are effectively suppressed.In addition,we put forward the growth rate of swelling ratio(GSR)as a key indicator to reveal the swelling change in SEI.The GSR of bilayer SEI merely increases from1.73 to 3.16 after the 300th cycle,which enables the corresponding graphite‖Li battery to achieve longer cycle stability.The capacity retention is improved by 47.5% after 300 cycles at 0.5 C.The correlation among SEI spatial structure,swelling behavior,and battery performance provides a new direction for electrolyte optimization and interphase structure design of high energy density batteries.展开更多
By optimizing electrolyte formulation to inhibit the deposition of transition metal ions(TMIs) on the surface of the graphite anode is an effective way to improve the electrochemical performance of lithium-ion batteri...By optimizing electrolyte formulation to inhibit the deposition of transition metal ions(TMIs) on the surface of the graphite anode is an effective way to improve the electrochemical performance of lithium-ion batteries.At present,it is generally believed the formation of an effective interfacial film on the surface of the anode electrode is the leading factor in reducing the dissolution of TMIs and prevent TMIs from being embedded in the electrode.It ignores the influence of the solvation structures in the electrolyte system with different composition,and is not conducive to the design of the electrolyte formulation from the perspective of changing the concentration and the preferred solvent to inhibit the degradation of battery performance caused by TMIs deposition.In this work,by analyzing the special solvation structures of the high-concentra tion electrolyte,we study the main reason why high-concentration electrolyte inhibits the destructive effect of Mn(Ⅱ) on the electrochemical performance of LIBs.By combining the potentialresolved in-situ electrochemical impedance spectroscopy technology(PRIs-EIS) and density functional theory(DFT) calculation,we find that Mn(Ⅱ) mainly exists in the form of contact ions pairs(CIPs) and aggregates(AGGs) in high-concentration electrolyte.These solvation structures can reduce the destructive effect of Mn(Ⅱ) on battery performance from two aspects:on the one hand,it can rise the lowest unoccupied orbital(LUMO) value of the solvation structures of Mn(Ⅱ),thereby reducing the chance of its reduction;on the other hand,the decrease of Mn2+ions reduction can reduce the deposition of metallic manganese in the solid electrolyte interphase(SEI),thereby avoiding the continuous growth of the SEI.This study can be provided inspiration for the design of electrolytes to inhibit the destructive effect of TMls on LIBs.展开更多
Stable operation is one of the most important requirements for a laser source for high-precision applications.Many efforts have been made to improve the stability of lasers by employing various techniques,e.g.,electri...Stable operation is one of the most important requirements for a laser source for high-precision applications.Many efforts have been made to improve the stability of lasers by employing various techniques,e.g.,electrical and/or optical injection and phase locking.However,these techniques normally involve complex experimental facilities.Therefore,an easy implementation of the stability evaluation of a laser is still challenging,especially for lasers emitting in the terahertz(THz)frequency range because the broadband photodetectors and mature locking techniques are limited.In this work,we propose a simple method,i.e.,relative phase locking,to quickly evaluate the stability of THz lasers without a need of a THz local oscillator.The THz laser system consists of a THz quantum cascade laser(QCL)frequency comb and a single-mode QCL.Using the single-mode laser as a fast detector,heterodyne signals resulting from the beating between the singlemode laser and the comb laser are obtained.One of the heterodyne beating signals is selected and sent to a phase-locked loop(PLL)for implementing the relative phase locking.Two kinds of locks are performed by feeding the output error signal of the PLL,either to the comb laser or to the single-mode laser.By analyzing the current change and the corresponding frequency change of the PLL-controlled QCL in each phase-locking condition,we,in principle,are able to experimentally compare the stability of the emission frequency of the single-mode QCL(f s)and the carrier envelope offset frequency(f CEO)of the QCL comb.The experimental results reveal that the QCL comb with the repetition frequency injection locked demonstrates much higher stability than the single-mode laser.The work provides a simple heterodyne scheme for understanding the stability of THz lasers,which paves the way for the further locking of the lasers and their high-precision applications in the THz frequency range.展开更多
Frequency combs show various applications in molecular fingerprinting,imaging,communications,and so on.In the terahertz frequency range,semiconductor-based quantum cascade lasers(QCLs)are ideal platforms for realizing...Frequency combs show various applications in molecular fingerprinting,imaging,communications,and so on.In the terahertz frequency range,semiconductor-based quantum cascade lasers(QCLs)are ideal platforms for realizing the frequency comb operation.Although self-started frequency comb operation can be obtained in free-running terahertz QCLs due to the four-wave mixing locking effects,resonant/off-resonant microwave injection,phase locking,and femtosecond laser based locking techniques have been widely used to broaden and stabilize terahertz QCL combs.These active locking methods indeed show significant effects on the frequency stabilization of terahertz QCL combs,but they simultaneously have drawbacks,such as introducing large phase noise and requiring complex optical coupling and/or electrical circuits.Here,we demonstrate Farey tree locking of terahertz QCL frequency combs under microwave injection.The frequency competition between the Farey fraction frequency and the cavity round-trip frequency results in the frequency locking of terahertz QCL combs,and the Farey fraction frequencies can be accurately anticipated based on the downward trend of the Farey tree hierarchy.Furthermore,dual-comb experimental results show that the phase noise of the dual-comb spectral lines is significantly reduced by employing the Farey tree locking method.These results pave the way to deploying compact and low phase noise terahertz frequency comb sources.展开更多
Designing ultrathick and hierarchical electrodes is effective to deal with the challenge of high areal capacity and high power density for lithium-ion batteries(LIBs)manufacturing.Here,a thick electrode with hierarchi...Designing ultrathick and hierarchical electrodes is effective to deal with the challenge of high areal capacity and high power density for lithium-ion batteries(LIBs)manufacturing.Here,a thick electrode with hierarchical porous and multidimensional conductive network is fabricated by 3D printing tech-nology,in which both the conducting polymer of poly(3,4-ethylene dioxythiophene):polystyrene sul-fonate(PEDOT:PSS)and graphene oxide(GO)play the dual roles as binders and conductive agents.As a consequence,the 3D-printed thick electrode(~900 mm)with a mass loading of~47 mg/cm^(2) exhibits a good rate capability of 122 mA·h/g at 2 C,a high areal capacity of up to 5.8 mA·h/cm^(2),and stable cycling performance of~95%capacity retention after 100 cycles.Moreover,the C-O-S bond is further confirmed by the spectral analysis and the DFT calculation,which not only hinders the stack of nanosheets but enhances the mechanical stability and electronic conductivity of electrodes.A stable covalent multidi-mensional conductive network constructed by 3D-printing technology provides a new design strategy to improve the performance of LIBs.展开更多
We study the redistribution of quantum steering and its monogamy in the presence of a four-dimensional Kerr-Newman black hole.The gravitational effect of the Kerr-Newman black hole is shown to generate genuine tripart...We study the redistribution of quantum steering and its monogamy in the presence of a four-dimensional Kerr-Newman black hole.The gravitational effect of the Kerr-Newman black hole is shown to generate genuine tripartite steering between causally disconnected regions,depending on the polar angle,angular momentum,electric charge,and magnetic charge of the black hole.We obtain strong evidence of steering monogamy,that is,the"sudden death"of the A→B steering results in the"sudden birth"of B→B steering.We also obtain the condition of maximal steering asymmetry,that is,η0=√1+tanh^(2)(s),revealing the transition between two-way and one-way steering in Kerr-Newman spacetime.展开更多
基金supported by the National Natural Science Foundation of China(22369011)the Gansu Key Research and Development Program(23YFGA0053 and 24YFGA025)the Hongliu Outstanding Youth Talent Support Program of Lanzhou University of Technology and Postgraduate research exploration project of Lanzhou University of Technology(256017)。
文摘The swelling behavior and stability in solid electrolyte interphase(SEI)have been proved to determine the battery cycle life.A high swollen,unstable SEI shows a high permeability to electrolyte,which results in the rapid battery performance degradation.Here,we customize two SEIs with different spatial structures(bilayer and mosaic)by simply regulating the proportion of additive fluoroethylene carbonate.Surprisingly,due to the uniform distribution of dense inorganic nano-crystals in the inner,the bilayer SEI exhibits low-swelling and excellent mechanical properties,so the undesirable side reactions of the electrolyte are effectively suppressed.In addition,we put forward the growth rate of swelling ratio(GSR)as a key indicator to reveal the swelling change in SEI.The GSR of bilayer SEI merely increases from1.73 to 3.16 after the 300th cycle,which enables the corresponding graphite‖Li battery to achieve longer cycle stability.The capacity retention is improved by 47.5% after 300 cycles at 0.5 C.The correlation among SEI spatial structure,swelling behavior,and battery performance provides a new direction for electrolyte optimization and interphase structure design of high energy density batteries.
基金supported by the Natural Science Foundation of Gansu Province for Youths(21JR7RA254)the Gansu Provincial Department of Education: Innovation Fund Project(2022A-029)+1 种基金the Major Special Fund of Gansu Province(21ZD4GA031)the Lanzhou University of Technology Hongliu First-class Discipline Construction Program and Gansu Province Central Government Guided Local Science and Technology Development Fund ProjectIndustrialization of Automotive Low-Temperature Lithium-ion Battery Manufacturing Technology Achievements。
文摘By optimizing electrolyte formulation to inhibit the deposition of transition metal ions(TMIs) on the surface of the graphite anode is an effective way to improve the electrochemical performance of lithium-ion batteries.At present,it is generally believed the formation of an effective interfacial film on the surface of the anode electrode is the leading factor in reducing the dissolution of TMIs and prevent TMIs from being embedded in the electrode.It ignores the influence of the solvation structures in the electrolyte system with different composition,and is not conducive to the design of the electrolyte formulation from the perspective of changing the concentration and the preferred solvent to inhibit the degradation of battery performance caused by TMIs deposition.In this work,by analyzing the special solvation structures of the high-concentra tion electrolyte,we study the main reason why high-concentration electrolyte inhibits the destructive effect of Mn(Ⅱ) on the electrochemical performance of LIBs.By combining the potentialresolved in-situ electrochemical impedance spectroscopy technology(PRIs-EIS) and density functional theory(DFT) calculation,we find that Mn(Ⅱ) mainly exists in the form of contact ions pairs(CIPs) and aggregates(AGGs) in high-concentration electrolyte.These solvation structures can reduce the destructive effect of Mn(Ⅱ) on battery performance from two aspects:on the one hand,it can rise the lowest unoccupied orbital(LUMO) value of the solvation structures of Mn(Ⅱ),thereby reducing the chance of its reduction;on the other hand,the decrease of Mn2+ions reduction can reduce the deposition of metallic manganese in the solid electrolyte interphase(SEI),thereby avoiding the continuous growth of the SEI.This study can be provided inspiration for the design of electrolytes to inhibit the destructive effect of TMls on LIBs.
基金supported by the National Natural Science Foundation of China(Grant Nos.62235019,61875220,61927813,62035005,61991430,and 62105351)the“From 0 to 1”Innovation Program of the Chinese Academy of Sciences(Grant No.ZDBSLY-JSC009)+4 种基金the Scientific Instrument and Equipment Development Project of the Chinese Academy of Sciences(Grant No.YJKYYQ20200032)the CAS Project for Young Scientists in BasicResearch(Grant No.YSBR-069)the National Science Fund for Excellent Young Scholars(Grant No.62022084)the Shanghai Outstanding Academic Leaders Plan(Grant No.20XD1424700)the Shanghai Youth Top Talent Support Program.The authors have no conflicts to disclose.
文摘Stable operation is one of the most important requirements for a laser source for high-precision applications.Many efforts have been made to improve the stability of lasers by employing various techniques,e.g.,electrical and/or optical injection and phase locking.However,these techniques normally involve complex experimental facilities.Therefore,an easy implementation of the stability evaluation of a laser is still challenging,especially for lasers emitting in the terahertz(THz)frequency range because the broadband photodetectors and mature locking techniques are limited.In this work,we propose a simple method,i.e.,relative phase locking,to quickly evaluate the stability of THz lasers without a need of a THz local oscillator.The THz laser system consists of a THz quantum cascade laser(QCL)frequency comb and a single-mode QCL.Using the single-mode laser as a fast detector,heterodyne signals resulting from the beating between the singlemode laser and the comb laser are obtained.One of the heterodyne beating signals is selected and sent to a phase-locked loop(PLL)for implementing the relative phase locking.Two kinds of locks are performed by feeding the output error signal of the PLL,either to the comb laser or to the single-mode laser.By analyzing the current change and the corresponding frequency change of the PLL-controlled QCL in each phase-locking condition,we,in principle,are able to experimentally compare the stability of the emission frequency of the single-mode QCL(f s)and the carrier envelope offset frequency(f CEO)of the QCL comb.The experimental results reveal that the QCL comb with the repetition frequency injection locked demonstrates much higher stability than the single-mode laser.The work provides a simple heterodyne scheme for understanding the stability of THz lasers,which paves the way for the further locking of the lasers and their high-precision applications in the THz frequency range.
基金supported by the Innovation Program for Quantum Science and Technology(2023ZD0301000)the National Science Fund for Distinguished Young Scholars(62325509)+2 种基金the National Natural Science Foundation of China(62235019,61875220,61927813,61991430,62035005,62105351,and 62305364)the“From 0 to 1”Innovation Program of the Chinese Academy of Sciences(ZDBS-LY-JSC009)the CAS Project for Young Scientists in Basic Research(YSBR-069).
文摘Frequency combs show various applications in molecular fingerprinting,imaging,communications,and so on.In the terahertz frequency range,semiconductor-based quantum cascade lasers(QCLs)are ideal platforms for realizing the frequency comb operation.Although self-started frequency comb operation can be obtained in free-running terahertz QCLs due to the four-wave mixing locking effects,resonant/off-resonant microwave injection,phase locking,and femtosecond laser based locking techniques have been widely used to broaden and stabilize terahertz QCL combs.These active locking methods indeed show significant effects on the frequency stabilization of terahertz QCL combs,but they simultaneously have drawbacks,such as introducing large phase noise and requiring complex optical coupling and/or electrical circuits.Here,we demonstrate Farey tree locking of terahertz QCL frequency combs under microwave injection.The frequency competition between the Farey fraction frequency and the cavity round-trip frequency results in the frequency locking of terahertz QCL combs,and the Farey fraction frequencies can be accurately anticipated based on the downward trend of the Farey tree hierarchy.Furthermore,dual-comb experimental results show that the phase noise of the dual-comb spectral lines is significantly reduced by employing the Farey tree locking method.These results pave the way to deploying compact and low phase noise terahertz frequency comb sources.
基金supported by the Key Research of Gansu Province(21ZD4GA031)Development Program of Gansu Province(21YF5GA079)Excellent Postgraduate Innovation Star Project of Gansu Province(2022CXZX-422).
文摘Designing ultrathick and hierarchical electrodes is effective to deal with the challenge of high areal capacity and high power density for lithium-ion batteries(LIBs)manufacturing.Here,a thick electrode with hierarchical porous and multidimensional conductive network is fabricated by 3D printing tech-nology,in which both the conducting polymer of poly(3,4-ethylene dioxythiophene):polystyrene sul-fonate(PEDOT:PSS)and graphene oxide(GO)play the dual roles as binders and conductive agents.As a consequence,the 3D-printed thick electrode(~900 mm)with a mass loading of~47 mg/cm^(2) exhibits a good rate capability of 122 mA·h/g at 2 C,a high areal capacity of up to 5.8 mA·h/cm^(2),and stable cycling performance of~95%capacity retention after 100 cycles.Moreover,the C-O-S bond is further confirmed by the spectral analysis and the DFT calculation,which not only hinders the stack of nanosheets but enhances the mechanical stability and electronic conductivity of electrodes.A stable covalent multidi-mensional conductive network constructed by 3D-printing technology provides a new design strategy to improve the performance of LIBs.
基金Supported by the National Natural Science Foundation of China (12205133,LJKQZ20222315,JYTMS20231051)the Special Fund for Basic Scientific Research of Provincial Universities in Liaoning (LS2024Q002)。
文摘We study the redistribution of quantum steering and its monogamy in the presence of a four-dimensional Kerr-Newman black hole.The gravitational effect of the Kerr-Newman black hole is shown to generate genuine tripartite steering between causally disconnected regions,depending on the polar angle,angular momentum,electric charge,and magnetic charge of the black hole.We obtain strong evidence of steering monogamy,that is,the"sudden death"of the A→B steering results in the"sudden birth"of B→B steering.We also obtain the condition of maximal steering asymmetry,that is,η0=√1+tanh^(2)(s),revealing the transition between two-way and one-way steering in Kerr-Newman spacetime.
