A sol-gel method using lauric acid as surfactant was used to synthesize Li4Ti5O12 nanocrystals with an ultra-fine particle size distribution between 120 and 250 nm.In order to obtain the electrode materials with the b...A sol-gel method using lauric acid as surfactant was used to synthesize Li4Ti5O12 nanocrystals with an ultra-fine particle size distribution between 120 and 250 nm.In order to obtain the electrode materials with the best electrochemical performance,the content of lauric acid during Li4Ti5O12 synthesis was systematically studied.The physical and electrochemical properties of the synthesized samples were characterized by X-ray diffraction（XRD）,field emission scanning electron microscopy（FESEM）,transmission electron microscopy（TEM）,laser particle size analysis,alternating current impedance（AC） and galvanostatic charge-discharge experiments.The highly dispersed Li4Ti5O12 nanocrystals obtained at 800 ℃ for 10 h can deliver a specific capacity of 163.3 mA-h/g at 1C rate without obvious capacity fade up to 50 cycles.The results suggest that well dispersed Li4Ti5O12 nanocrystals shorten the Li-ion diffusion length and enhance the electrochemical kinetics of the samples,which are very crucial to high rate capability.展开更多
It is the core to improve the electron/ion transfer features of Li_(4)Ti_(5)O_(12) for achieving high-rate anode in lithium ion batteries.By directly using graphite oxide powder,nano-Li_(4)Ti_(5)O_(12)/reduced graphit...It is the core to improve the electron/ion transfer features of Li_(4)Ti_(5)O_(12) for achieving high-rate anode in lithium ion batteries.By directly using graphite oxide powder,nano-Li_(4)Ti_(5)O_(12)/reduced graphite oxide composite with mesopore-oriented porosity is prepared through one-pot facile ball-milling method in this work.Synthesis mechanism underlying the self-nucleophilic effect of oxygen-containing functional groups in graphite oxide is substantiated.Reactants can intercalate into graphite oxide bulk and in-situ generate nanoparticles.Subsequently,graphite oxide with nanoparticles generated inside can obtain a mesopore-oriented porous structure under ball-milling.Furthermore,the synergistic effects of Li_(4)Ti_(5)O_(12) nanoparticles and mesopore-oriented porosity strengthen composites with rapid Li^(+)diffusion and electron conductive frameworks.The obtained optimal LTO/GO-1.75 composite displays excellent high-rate capability(136 mA·h/g at 7000 mA/g)and good cycling stability(a capacity retention of 72%after 1000 cycles at 7000 mA/g).Additionally,the reactants concentration in this demonstrated strategy is as high as 30 wt%−40 wt%,which is over 6 times that of traditional methods with GO suspensions.It means that the strategy can significantly increase the yield,showing big potential for large-scale production.展开更多
The development of reliable and affordable all-solid-state sodium metal batteries(ASS-SMBs)requires suitable solid-state electrolytes with cost-efficient processing and stabilized electrode/electrolyte interfaces.Here...The development of reliable and affordable all-solid-state sodium metal batteries(ASS-SMBs)requires suitable solid-state electrolytes with cost-efficient processing and stabilized electrode/electrolyte interfaces.Here,an integrated porous/dense/porous Na_(5)YSi_(4)O_(12)(NYS)trilayered scaffold is designed and fabricated by tape casting using aqueous slurries.In this template-based NYS scaffold,the dense layer in the middle serves as a separator and the porous layers on both sides accommodate the active materials with their volume changes during the charge/discharge processes,increasing the contact area and thus enhancing the utilization rate and homogenizing the current distribution.The Na/NYS/Na symmetric cells with the Pb-coated NYS scaffold exhibit significantly reduced interfacial impedance and superior critical current density of up to 3.0 mA cm^(-2)against Na metal owing to enhanced wettability.Furthermore,the assembled Na/NYS/S full cells operated without external pressure at room temperature showed a high initial discharge capacity of 970 mAh g^(-1)and good cycling stability with a capacity of 600 mAh g^(-1)after 150 cycles(based on the mass of sulfur).This approach paves the way for the realization of economical and practical ASS-SMBs from the perspective of ceramic manufacturing.展开更多
采用溶胶-凝胶法制备了CaCu_(3)Ti_(4)O_(12)粉体,压制成型工艺和传统烧结工艺制备了CaCu_(3)Ti_(4)O_(12)陶瓷样品,研究了CaCu_(3)Ti_(4)O_(12)陶瓷的相结构与烧结工艺的关系,表征并讨论了CaCu_(3)Ti_(4)O_(12)陶瓷的负温度系数(NTC,Ne...采用溶胶-凝胶法制备了CaCu_(3)Ti_(4)O_(12)粉体,压制成型工艺和传统烧结工艺制备了CaCu_(3)Ti_(4)O_(12)陶瓷样品,研究了CaCu_(3)Ti_(4)O_(12)陶瓷的相结构与烧结工艺的关系,表征并讨论了CaCu_(3)Ti_(4)O_(12)陶瓷的负温度系数(NTC,Negative Temperature Coefficient)电阻特性,如电阻率(ρ)、热敏常数(B)、线性度和迟滞。实验结果证明:所制备的陶瓷坯体经950℃、1000℃、1050℃和1100℃烧结后可得到纯钙钛矿相的CaCu_(3)Ti_(4)O_(12)陶瓷;同时具有良好的NTC特性,室温电阻率(ρ25)为1.5×107Ω·cm,热敏常数为6223~6874 K;线性度和迟滞分别为1.50%和1.00%。展开更多
文摘采用固相反应法制备了Ca Cu_(3)Ti_(4)O_(12)(CCTO)及Y^(3+)掺杂的Ca_(0.97)Y_(0.03)Cu_(3)Ti_(4)O_(12) (CYCTO)陶瓷,研究了陶瓷烧成过程中采用随炉冷却和在空气中快速冷却的工艺对陶瓷样品物相结构、微观形貌和介电性能的影响。结果表明,当采用随炉冷却工艺时,Y^(3+)掺杂的CYCTO陶瓷的介电常数(ε′)相对于未掺杂的CCTO陶瓷有所提高,同时介电损耗(tanδ)也得到同步降低。而当采用在空气中快速冷却的工艺时,CYCTO陶瓷的ε′和tanδ得到进一步优化。阻抗分析表明,在空气中快速冷却的CYCTO陶瓷的晶粒导电性和晶界的绝缘性得到同步提高,从而增强了CYCTO陶瓷的介电响应而提高了ε′;而晶界绝缘性地提高导致了tanδ的进一步降低。快速冷却的CYCTO陶瓷在1 k Hz时,其ε′高达4.06×10~4,tanδ降低到0.036,其介电性能比随炉冷却的CCTO陶瓷(ε′=1.68×10~4,tanδ=0.16)得到显著提升。
基金Project(2007CB2097050)supported by the National Basic Research Program of ChinaProject(20803035)supported by the National Natural Science Foundation of ChinaProject supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD),China
文摘A sol-gel method using lauric acid as surfactant was used to synthesize Li4Ti5O12 nanocrystals with an ultra-fine particle size distribution between 120 and 250 nm.In order to obtain the electrode materials with the best electrochemical performance,the content of lauric acid during Li4Ti5O12 synthesis was systematically studied.The physical and electrochemical properties of the synthesized samples were characterized by X-ray diffraction（XRD）,field emission scanning electron microscopy（FESEM）,transmission electron microscopy（TEM）,laser particle size analysis,alternating current impedance（AC） and galvanostatic charge-discharge experiments.The highly dispersed Li4Ti5O12 nanocrystals obtained at 800 ℃ for 10 h can deliver a specific capacity of 163.3 mA-h/g at 1C rate without obvious capacity fade up to 50 cycles.The results suggest that well dispersed Li4Ti5O12 nanocrystals shorten the Li-ion diffusion length and enhance the electrochemical kinetics of the samples,which are very crucial to high rate capability.
基金Project(21875283) supported by the the National Natural Science Foundation of China。
文摘It is the core to improve the electron/ion transfer features of Li_(4)Ti_(5)O_(12) for achieving high-rate anode in lithium ion batteries.By directly using graphite oxide powder,nano-Li_(4)Ti_(5)O_(12)/reduced graphite oxide composite with mesopore-oriented porosity is prepared through one-pot facile ball-milling method in this work.Synthesis mechanism underlying the self-nucleophilic effect of oxygen-containing functional groups in graphite oxide is substantiated.Reactants can intercalate into graphite oxide bulk and in-situ generate nanoparticles.Subsequently,graphite oxide with nanoparticles generated inside can obtain a mesopore-oriented porous structure under ball-milling.Furthermore,the synergistic effects of Li_(4)Ti_(5)O_(12) nanoparticles and mesopore-oriented porosity strengthen composites with rapid Li^(+)diffusion and electron conductive frameworks.The obtained optimal LTO/GO-1.75 composite displays excellent high-rate capability(136 mA·h/g at 7000 mA/g)and good cycling stability(a capacity retention of 72%after 1000 cycles at 7000 mA/g).Additionally,the reactants concentration in this demonstrated strategy is as high as 30 wt%−40 wt%,which is over 6 times that of traditional methods with GO suspensions.It means that the strategy can significantly increase the yield,showing big potential for large-scale production.
基金the China Scholarship Council(CSC,No.201906200023)the MatKat Foundation.Aikai Yang,whose CSC grant application is affiliated with Nankai University(Tianjin,China)the Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education)at Nankai University.Partial financial support from the German Federal Ministry of Education and Research(BMBF)within the project“HeNa”(support code 13XP0390B)is also gratefully acknowledged.
文摘The development of reliable and affordable all-solid-state sodium metal batteries(ASS-SMBs)requires suitable solid-state electrolytes with cost-efficient processing and stabilized electrode/electrolyte interfaces.Here,an integrated porous/dense/porous Na_(5)YSi_(4)O_(12)(NYS)trilayered scaffold is designed and fabricated by tape casting using aqueous slurries.In this template-based NYS scaffold,the dense layer in the middle serves as a separator and the porous layers on both sides accommodate the active materials with their volume changes during the charge/discharge processes,increasing the contact area and thus enhancing the utilization rate and homogenizing the current distribution.The Na/NYS/Na symmetric cells with the Pb-coated NYS scaffold exhibit significantly reduced interfacial impedance and superior critical current density of up to 3.0 mA cm^(-2)against Na metal owing to enhanced wettability.Furthermore,the assembled Na/NYS/S full cells operated without external pressure at room temperature showed a high initial discharge capacity of 970 mAh g^(-1)and good cycling stability with a capacity of 600 mAh g^(-1)after 150 cycles(based on the mass of sulfur).This approach paves the way for the realization of economical and practical ASS-SMBs from the perspective of ceramic manufacturing.
文摘采用溶胶-凝胶法制备了CaCu_(3)Ti_(4)O_(12)粉体,压制成型工艺和传统烧结工艺制备了CaCu_(3)Ti_(4)O_(12)陶瓷样品,研究了CaCu_(3)Ti_(4)O_(12)陶瓷的相结构与烧结工艺的关系,表征并讨论了CaCu_(3)Ti_(4)O_(12)陶瓷的负温度系数(NTC,Negative Temperature Coefficient)电阻特性,如电阻率(ρ)、热敏常数(B)、线性度和迟滞。实验结果证明:所制备的陶瓷坯体经950℃、1000℃、1050℃和1100℃烧结后可得到纯钙钛矿相的CaCu_(3)Ti_(4)O_(12)陶瓷;同时具有良好的NTC特性,室温电阻率(ρ25)为1.5×107Ω·cm,热敏常数为6223~6874 K;线性度和迟滞分别为1.50%和1.00%。
