The Li_(2)ZnTi_(3)O_(8)@Li AlO_(2)was synthesized by a facile high-temperature solid-state route.The LiAlO_(2)modification does not alter the morphology and particle size of Li_(2)Zn Ti_(3)O_(8)(LZTO).The LiAlO_(2)mod...The Li_(2)ZnTi_(3)O_(8)@Li AlO_(2)was synthesized by a facile high-temperature solid-state route.The LiAlO_(2)modification does not alter the morphology and particle size of Li_(2)Zn Ti_(3)O_(8)(LZTO).The LiAlO_(2)modification improves the structure stability,intercalation/deintercalation reversibility of lithium-ions,and electrochemical reaction activity of Li_(2)Zn Ti_(3)O_(8),and promotes the transfer of lithium ions.Benefited from the unique component,Li_(2)Zn Ti_(3)O_(8)@Li AlO_(2)(8wt%) shows a good rate performance with charge capacities of 203.9,194.8,187.4,180.6,and177.1 mAh·g^(-1)at 0.5,1,2,3,and 5 C,respectively.Nevertheless,pure LZTO only delivers charge capacities of 134.5,109.7,89.4,79.9,and 72.9 mAh·g^(-1)at the corresponding rates.Even at large charge–discharge rate,the Li_(2)Zn Ti_(3)O_(8)@Li AlO_(2)(8wt%) composite indicates a good cycle performance with a high reversible charge/discharge capacity of 263.5/265.8 mAh·g^(-1)at 5 C after 150 cycles.The introduction of LiAlO_(2)on the surface of Li_(2)Zn Ti_(3)O_(8)enhances electronic conductivity of the composite,resulting in the good electrochemical performance of Li_(2)Zn Ti_(3)O_(8)@Li AlO_(2)composite.Li_(2)Zn Ti_(3)O_(8)@LiAlO_(2)(8wt%) composite shows a good potential as an anode material for the next generation of high-performance Li-ion batteries.展开更多
The diffusion and loss of lithium polysulfides(LiPSs)in lithium-sulfur batteries(LSBs)reduce the sulfur utilization rate and the catalytic conversion efficiency of sulfur species,resulting in early battery failure.Li_...The diffusion and loss of lithium polysulfides(LiPSs)in lithium-sulfur batteries(LSBs)reduce the sulfur utilization rate and the catalytic conversion efficiency of sulfur species,resulting in early battery failure.Li_(2)ZnTi_(3)O_(8)(LZTO),characterized by its stable spinel structure,exhibits high Li+conductivity and holds great potential as an effective adsorbent for LiPSs.This study proposes a collaborative design concept of LZTO host–separator modifier,which offers a complementary and matching approach in the cathode side,effectively addressing the challenges associated with dissolution and inadequate conversion of LiPSs.Density functional theory(DFT)calculation substantiates the pronounced chemical affinity of LZTO towards LiPSs.More importantly,the high efficiency ion transport channels are achieved in separator coating due to the presence of the LZTO particles.Furthermore,the catalytic efficacy of LZTO is validated through meticulous analysis of symmetric batteries and Tafel curves.Consequently,the LZTO host–separator modifier-based cell displays satisfactory rate capability(1449 and 1166 mAh·g^(−1)at 0.1 and 0.5 C)and an impressively capacity(606 mAh·g^(−1)after 500 cycles at 1 C).The coordinated strategy of host–separator modifier is supposed to have wide applications in LSBs.展开更多
Polyacrylonitrile(PAN)with C≡N bonds can be converted to nitrogen-doped carbon during carbonization,which enhances electronic conductivity by compensating for the deficiency of the Li_(2)ZnTi_(3)O_(8)(LZTO)anode.In t...Polyacrylonitrile(PAN)with C≡N bonds can be converted to nitrogen-doped carbon during carbonization,which enhances electronic conductivity by compensating for the deficiency of the Li_(2)ZnTi_(3)O_(8)(LZTO)anode.In this study,LZTO was modified by carbonizing a homogeneous PAN/LZTO powder mixture at approximately 800℃for 5 h in nitrogen stream to uniformly coat nitrogen-doped carbon around the LZTO particles and to yield nitrogen-doped LZTO.PAN-60 exhibited a capacity retention of 74.8%as the current density increased from 0.1 to 1.6 A g−1,and had charge/discharge capacities of 250.1/250.8 mAh g−1 even after 1100 cycles at 0.5 A g−1.Structural and compositional analysis along with electrochemical tests showed that the uniform nitrogen-doped carbon coating and the nitrogen-doped LZTO favor electron transfer,while the defects induced by nitrogen-doping in LZTO promote Li-ion migration.The enhanced electronic and ionic conductivities are favorable to alleviate the polarization during cycling,and thus are responsible for the optimized performance.展开更多
锂硫电池中多硫化锂的“穿梭效应”、单质硫导电性差等问题导致其寿命短、倍率性能差,严重限制了其实际应用.基于此,本文采用溶胶凝胶法合成了尖晶石型Li_(2)MnTi_(3)O_(8)(LMTO)纳米颗粒,将其同时作为硫宿主材料和功能隔膜涂层,极大地...锂硫电池中多硫化锂的“穿梭效应”、单质硫导电性差等问题导致其寿命短、倍率性能差,严重限制了其实际应用.基于此,本文采用溶胶凝胶法合成了尖晶石型Li_(2)MnTi_(3)O_(8)(LMTO)纳米颗粒,将其同时作为硫宿主材料和功能隔膜涂层,极大地提升了锂硫电池的循环稳定性和Li+的扩散速率.均匀分散的LMTO纳米颗粒不仅能提供丰富的电化学活性位点,同时可减少活性硫的损失.此外,LMTO功能化隔膜具有吸附多硫化锂的能力,有效抑制了多硫化锂的穿梭.实验结果表明,以LMTO为硫宿主材料和功能隔膜涂层组装的锂硫电池在充放电过程中展现了较快的锂离子扩散速率(DLi+分别为2.25×10^(−5),1.31×10^(−5)和1.61×10^(−4)cm^(2)s^(−1)),表明其快速的反应动力学.在0.5 C的电流密度下,电池首次放电比容量可达到1059 mAh g^(−1),经过300次循环,容量稳定在797 mAh g^(−1).双功能改性后的电池性能均优于单功能改性的电池.该材料的双功能应用策略为开发高容量、长寿命的锂硫电池提供了理论支持.展开更多
Complex ion substitution is gaining more attention as an appealing method of modifying the structure and performance of microwave ceramics.In this work,Li_(2)Zn[Ti_(1-x)(Ni_(1/3)Nb_(2/3))_(x)]_(3)O_(8),0≤x≤0.3cerami...Complex ion substitution is gaining more attention as an appealing method of modifying the structure and performance of microwave ceramics.In this work,Li_(2)Zn[Ti_(1-x)(Ni_(1/3)Nb_(2/3))_(x)]_(3)O_(8),0≤x≤0.3ceramics were designed based on the complex ion substitution strategy,following the substitution rule of radius and valence to investigate the relationship among phase compositions(containing oxygen vacancies and Ti^(3+)ions),microstructures,and microwave dielectric characteristics of the LZTNNx ceramics.The samples maintained a single Li_(2)ZnTi_(3)O_(8)solid solution phase as x≤0.2,whereas the sample of x=0.3 produced a second phase with the LiNbO_(3)structure.The appropriate amount of(Ni_(1/3)Nb_(2/3))^(4+)substitution could slightly improve the densification of the LZTNNx ceramics due to the formation of the LiZnTi_(3)O_(8)solid solution accompanied by a decrease in the average grain size.The presence of a new Aig Raman active band at about 848 cm^(-1)indicated that local symmetry changed,affecting atomic interactions of the LZTNNx ceramics.The variation of the relative dielectric constant(εr)was closely related to the molar volume ionic polarizability(α_(D)^(T)),and the temperature coefficient of the resonant frequency(τ_(f))was related to the bond valence(V_(1))of Ti.The increase in density,the absence of the Ti3+ions and oxygen vacancies,and the reduction in damping behavior were responsible for the decreased dielectric loss.The LZTNNO.2 ceramics sintered at 1120℃exhibited favorable microwave dielectric properties:εr=22.13,quality factor(Q×f)=97,350 GHz,andτ_(f)=-18.60 ppm/C,which might be a promising candidate for wireless communication applications in highly selective electronics.展开更多
Reinforcing electronic and ionic conductivity is very important to realize the high-rate Li_(2)ZnTi_(3)O_(8)(LZTO)anode for Lithium-ion batteries(LIBs).Here,we reported a synthetic strategy toward in situ growth of ho...Reinforcing electronic and ionic conductivity is very important to realize the high-rate Li_(2)ZnTi_(3)O_(8)(LZTO)anode for Lithium-ion batteries(LIBs).Here,we reported a synthetic strategy toward in situ growth of homodispersed Li_(2)ZnTi_(3)O_(8)on ultralight 3D carbon aerogels(CAs)via facile heat treatment and activation process taking LiOH as activating agent.Such an optimized composite obtains a specific surface area of 154.427 m^(2) g^(-1) and a high pore volume.The strong interaction between the LZTO and N-doped CAs,a highly electrical conductivity and multidimensional ion transport channels of the hybrid result in a high capacity,outstanding high-rate performance and long cycle life.As a result,the NPC-LZTO electrode(NPC-LZTO-B)delivers a commendable reversible capacity at high-rate(e.g.162.4 mAh g^(-1) at 5 A g^(-1)(22 C)and 127.3 mAh g^(-1) at 10 A g^(-1))and durable long-term performance(capacity retention of 73% after 4500 cycles at 5 A g^(-1)).Moreover,the kinetic analysis confirms that the feature of pseudocapacitance boosts lithium-ion storage performance at high rate.Porous carbon aerogels frame constructed LZTO nanocomposite electrodes provide a facile way to design high durable LIBs anode.展开更多
A series of 20Li_(2)O-30V_(2)O_(5)-(50-x)SiO_(2)-xB_(2)O_(3)(mol.%)(x=10,20,30,40)glasses were prepared by the traditional melt-quenching synthesis.The amorphous nature of the glasses was determined by XRD,DSC and TEM...A series of 20Li_(2)O-30V_(2)O_(5)-(50-x)SiO_(2)-xB_(2)O_(3)(mol.%)(x=10,20,30,40)glasses were prepared by the traditional melt-quenching synthesis.The amorphous nature of the glasses was determined by XRD,DSC and TEM investigations.FTIR measurement revealed the functional group of obtained glasses.And EDS results confirmed the presence and uniform distribution of elements in the glasses.20Li_(2)O-30V_(2)O_(5)-40SiO_(2)-10B_(2)O_(3)(LVSB10)sample with the highest V^(4+) ratio exhibited the best cycling capacity.In order to further improve cycling stability of LVSB10 sample,ball milling was employed to reduce the particle size.The ball milled LVSB10 sample(LVSB10-b)showed an improved first discharge capacity,cycling stability and rate capacity.EIS measurements showed that ball milling can effectively decrease charge transfer impedance and facilitate Li^(+) ion diffusion.This work provides a new way to explore a new type of cathode materials for lithium ion batteries.展开更多
基金supported by the National Natural Science Foundation of China (No.U1960107)the“333”Talent Project of Hebei Province,China (No.A202005018)+1 种基金the Fundamental Research Funds for the Central Universities(No.N2123001)the Performance Subsidy Fund for Key Laboratory of Dielectric and Electrolyte Functional Material Hebei Province,China (No.22567627H)。
文摘The Li_(2)ZnTi_(3)O_(8)@Li AlO_(2)was synthesized by a facile high-temperature solid-state route.The LiAlO_(2)modification does not alter the morphology and particle size of Li_(2)Zn Ti_(3)O_(8)(LZTO).The LiAlO_(2)modification improves the structure stability,intercalation/deintercalation reversibility of lithium-ions,and electrochemical reaction activity of Li_(2)Zn Ti_(3)O_(8),and promotes the transfer of lithium ions.Benefited from the unique component,Li_(2)Zn Ti_(3)O_(8)@Li AlO_(2)(8wt%) shows a good rate performance with charge capacities of 203.9,194.8,187.4,180.6,and177.1 mAh·g^(-1)at 0.5,1,2,3,and 5 C,respectively.Nevertheless,pure LZTO only delivers charge capacities of 134.5,109.7,89.4,79.9,and 72.9 mAh·g^(-1)at the corresponding rates.Even at large charge–discharge rate,the Li_(2)Zn Ti_(3)O_(8)@Li AlO_(2)(8wt%) composite indicates a good cycle performance with a high reversible charge/discharge capacity of 263.5/265.8 mAh·g^(-1)at 5 C after 150 cycles.The introduction of LiAlO_(2)on the surface of Li_(2)Zn Ti_(3)O_(8)enhances electronic conductivity of the composite,resulting in the good electrochemical performance of Li_(2)Zn Ti_(3)O_(8)@Li AlO_(2)composite.Li_(2)Zn Ti_(3)O_(8)@LiAlO_(2)(8wt%) composite shows a good potential as an anode material for the next generation of high-performance Li-ion batteries.
基金supported by the National Natural Science Foundation of China(No.22278347)State Key Laboratory of Physical Chemistry of Solid Surface(No.2021X21)State Key Laboratory of Chemistry and Utilization of Carbon Based Energy Resources.
文摘The diffusion and loss of lithium polysulfides(LiPSs)in lithium-sulfur batteries(LSBs)reduce the sulfur utilization rate and the catalytic conversion efficiency of sulfur species,resulting in early battery failure.Li_(2)ZnTi_(3)O_(8)(LZTO),characterized by its stable spinel structure,exhibits high Li+conductivity and holds great potential as an effective adsorbent for LiPSs.This study proposes a collaborative design concept of LZTO host–separator modifier,which offers a complementary and matching approach in the cathode side,effectively addressing the challenges associated with dissolution and inadequate conversion of LiPSs.Density functional theory(DFT)calculation substantiates the pronounced chemical affinity of LZTO towards LiPSs.More importantly,the high efficiency ion transport channels are achieved in separator coating due to the presence of the LZTO particles.Furthermore,the catalytic efficacy of LZTO is validated through meticulous analysis of symmetric batteries and Tafel curves.Consequently,the LZTO host–separator modifier-based cell displays satisfactory rate capability(1449 and 1166 mAh·g^(−1)at 0.1 and 0.5 C)and an impressively capacity(606 mAh·g^(−1)after 500 cycles at 1 C).The coordinated strategy of host–separator modifier is supposed to have wide applications in LSBs.
基金project ZR2019MEM029 of Shandong Provincial Natural Science Foundation,PR China,and National Natural Science Foundation of China(51902189).Supplementary materials。
文摘Polyacrylonitrile(PAN)with C≡N bonds can be converted to nitrogen-doped carbon during carbonization,which enhances electronic conductivity by compensating for the deficiency of the Li_(2)ZnTi_(3)O_(8)(LZTO)anode.In this study,LZTO was modified by carbonizing a homogeneous PAN/LZTO powder mixture at approximately 800℃for 5 h in nitrogen stream to uniformly coat nitrogen-doped carbon around the LZTO particles and to yield nitrogen-doped LZTO.PAN-60 exhibited a capacity retention of 74.8%as the current density increased from 0.1 to 1.6 A g−1,and had charge/discharge capacities of 250.1/250.8 mAh g−1 even after 1100 cycles at 0.5 A g−1.Structural and compositional analysis along with electrochemical tests showed that the uniform nitrogen-doped carbon coating and the nitrogen-doped LZTO favor electron transfer,while the defects induced by nitrogen-doping in LZTO promote Li-ion migration.The enhanced electronic and ionic conductivities are favorable to alleviate the polarization during cycling,and thus are responsible for the optimized performance.
文摘锂硫电池中多硫化锂的“穿梭效应”、单质硫导电性差等问题导致其寿命短、倍率性能差,严重限制了其实际应用.基于此,本文采用溶胶凝胶法合成了尖晶石型Li_(2)MnTi_(3)O_(8)(LMTO)纳米颗粒,将其同时作为硫宿主材料和功能隔膜涂层,极大地提升了锂硫电池的循环稳定性和Li+的扩散速率.均匀分散的LMTO纳米颗粒不仅能提供丰富的电化学活性位点,同时可减少活性硫的损失.此外,LMTO功能化隔膜具有吸附多硫化锂的能力,有效抑制了多硫化锂的穿梭.实验结果表明,以LMTO为硫宿主材料和功能隔膜涂层组装的锂硫电池在充放电过程中展现了较快的锂离子扩散速率(DLi+分别为2.25×10^(−5),1.31×10^(−5)和1.61×10^(−4)cm^(2)s^(−1)),表明其快速的反应动力学.在0.5 C的电流密度下,电池首次放电比容量可达到1059 mAh g^(−1),经过300次循环,容量稳定在797 mAh g^(−1).双功能改性后的电池性能均优于单功能改性的电池.该材料的双功能应用策略为开发高容量、长寿命的锂硫电池提供了理论支持.
基金the Natural Science Foundation of Anhui Provincial Education Department(KJ2019A0054)the Anhui Provincial Natural Science Foundation(1608085ME92).
文摘Complex ion substitution is gaining more attention as an appealing method of modifying the structure and performance of microwave ceramics.In this work,Li_(2)Zn[Ti_(1-x)(Ni_(1/3)Nb_(2/3))_(x)]_(3)O_(8),0≤x≤0.3ceramics were designed based on the complex ion substitution strategy,following the substitution rule of radius and valence to investigate the relationship among phase compositions(containing oxygen vacancies and Ti^(3+)ions),microstructures,and microwave dielectric characteristics of the LZTNNx ceramics.The samples maintained a single Li_(2)ZnTi_(3)O_(8)solid solution phase as x≤0.2,whereas the sample of x=0.3 produced a second phase with the LiNbO_(3)structure.The appropriate amount of(Ni_(1/3)Nb_(2/3))^(4+)substitution could slightly improve the densification of the LZTNNx ceramics due to the formation of the LiZnTi_(3)O_(8)solid solution accompanied by a decrease in the average grain size.The presence of a new Aig Raman active band at about 848 cm^(-1)indicated that local symmetry changed,affecting atomic interactions of the LZTNNx ceramics.The variation of the relative dielectric constant(εr)was closely related to the molar volume ionic polarizability(α_(D)^(T)),and the temperature coefficient of the resonant frequency(τ_(f))was related to the bond valence(V_(1))of Ti.The increase in density,the absence of the Ti3+ions and oxygen vacancies,and the reduction in damping behavior were responsible for the decreased dielectric loss.The LZTNNO.2 ceramics sintered at 1120℃exhibited favorable microwave dielectric properties:εr=22.13,quality factor(Q×f)=97,350 GHz,andτ_(f)=-18.60 ppm/C,which might be a promising candidate for wireless communication applications in highly selective electronics.
基金This work was financially supported by Science and Technology Commission of Shanghai Municipality(19DZ2271100).
文摘Reinforcing electronic and ionic conductivity is very important to realize the high-rate Li_(2)ZnTi_(3)O_(8)(LZTO)anode for Lithium-ion batteries(LIBs).Here,we reported a synthetic strategy toward in situ growth of homodispersed Li_(2)ZnTi_(3)O_(8)on ultralight 3D carbon aerogels(CAs)via facile heat treatment and activation process taking LiOH as activating agent.Such an optimized composite obtains a specific surface area of 154.427 m^(2) g^(-1) and a high pore volume.The strong interaction between the LZTO and N-doped CAs,a highly electrical conductivity and multidimensional ion transport channels of the hybrid result in a high capacity,outstanding high-rate performance and long cycle life.As a result,the NPC-LZTO electrode(NPC-LZTO-B)delivers a commendable reversible capacity at high-rate(e.g.162.4 mAh g^(-1) at 5 A g^(-1)(22 C)and 127.3 mAh g^(-1) at 10 A g^(-1))and durable long-term performance(capacity retention of 73% after 4500 cycles at 5 A g^(-1)).Moreover,the kinetic analysis confirms that the feature of pseudocapacitance boosts lithium-ion storage performance at high rate.Porous carbon aerogels frame constructed LZTO nanocomposite electrodes provide a facile way to design high durable LIBs anode.
基金financially supported by Shenzhen Basic Research Project Funds(JCYJ20170817161127616).
文摘A series of 20Li_(2)O-30V_(2)O_(5)-(50-x)SiO_(2)-xB_(2)O_(3)(mol.%)(x=10,20,30,40)glasses were prepared by the traditional melt-quenching synthesis.The amorphous nature of the glasses was determined by XRD,DSC and TEM investigations.FTIR measurement revealed the functional group of obtained glasses.And EDS results confirmed the presence and uniform distribution of elements in the glasses.20Li_(2)O-30V_(2)O_(5)-40SiO_(2)-10B_(2)O_(3)(LVSB10)sample with the highest V^(4+) ratio exhibited the best cycling capacity.In order to further improve cycling stability of LVSB10 sample,ball milling was employed to reduce the particle size.The ball milled LVSB10 sample(LVSB10-b)showed an improved first discharge capacity,cycling stability and rate capacity.EIS measurements showed that ball milling can effectively decrease charge transfer impedance and facilitate Li^(+) ion diffusion.This work provides a new way to explore a new type of cathode materials for lithium ion batteries.
