采用高温固相法成功合成了新型钛基负极材料Na_2Li_2Ti_6O_(14),并研究了其结构及电化学性能。利用高分辨透明电镜(HRTEM)、X射线衍射(XRD)及其Rietveld精修、扫描电子显微镜(SEM)及能谱分析(EDS)表征分析了材料的物相和显微结构。结果...采用高温固相法成功合成了新型钛基负极材料Na_2Li_2Ti_6O_(14),并研究了其结构及电化学性能。利用高分辨透明电镜(HRTEM)、X射线衍射(XRD)及其Rietveld精修、扫描电子显微镜(SEM)及能谱分析(EDS)表征分析了材料的物相和显微结构。结果表明,合成的Na_2Li_2Ti_6O_(14)负极材料为纯相,具有Fmmm空间群结构;Na_2Li_2Ti_6O_(14)颗粒约为500~800 nm,Na、Ti和O三种元素分布均匀。循环伏安(CV)、充放电及电化学阻抗谱(EIS)测试表明,材料具有较好的锂离子脱嵌可逆性,较好的倍率性能和循环稳定性。钛电流密度为500 m A/g充放电时,Na_2Li_2Ti_6O_(14)材料的首次脱锂(充电)容量为180 m A·h/g,100次循环后可逆容量为136 m A·h/g;100次循环后,Na_2Li_2Ti_6O_(14)材料的电荷转移电阻增加,锂离子扩散系数略有下降,表明Na_2Li_2Ti_6O_(14)材料在循环后SEI膜的生成,降低了材料的电化学活性。展开更多
A series of Ba Li_（2-x）NaxTi_6O_（14）（0≤x≤2） compounds as lithium storage materials were synthesized by a facile solidstate method. X-ray diffraction Rietveld refinement shows that the Bragg positions correspon...A series of Ba Li_（2-x）NaxTi_6O_（14）（0≤x≤2） compounds as lithium storage materials were synthesized by a facile solidstate method. X-ray diffraction Rietveld refinement shows that the Bragg positions correspond to the Ba Li_2Ti_6O_（14）, indicating a successful preparation. The Na＋ions doped Ba Li_2-Ti_6O_（14） compounds have larger unit-cell volume than the pristine one because ionic radius of Na＋ion is 55% larger than that of Li＋ion. SEM shows that the Ba Li_2-xNaxTi_6O_（14）（x=0, 0.5 and1） powders show similar irregular shaped particles between500 and 1000 nm. However, Ba Li_2-xNaxTi_6O_（14）（x=1.5 and 2）powders show similar rod-like shape. CV reveals that the passivating film is mainly formed during the first insertion process, and the solid electrolyte interface film on the surface of Ba Li_2-xNaxTi_6O_（14）（0≤x≤2） is formed below 0.7 V in the first cycle. Compared with other samples, Ba Li_0.5Na1.5Ti_6O_（14） exhibits higher reversible capacity, better rate capability and superior cyclability. Ba Li_0.5Na1.5Ti_6O_（14） delivers the delithiation capacities of 162.1 mAhg^-（1）at 50 m A g^-（1）, 158.1 mAhg^-（1）at 100 m A g^-（1）, 156.7 mAhg^-（1）at 150 m A g^-（1）, 152.2 mAhg^-（1）at 200 m A g^-（1）, 147.3 mAhg^-（1）at 250 m A g^-（1）and 142 mAhg^-（1）at 300 m A g^-（1）, respectively. An interesting thing is that Ba Na2Ti_6O_（14） as anode also shows an acceptable electrochemical performance. All these improved electrochemical performances of Ba Li_0.5Na1.5Ti_6O_（14） are attributed to the lowest polarization and the highest lithium ion diffusion coefficient among all samples.Hence, Ba Li_0.5Na1.5Ti_6O_（14） with excellent cycling performance,simple synthesis route and wide discharge voltage range can be a possible anode candidate for lithium-ion batteries.展开更多
Relying on a solvent thermal method, spherical Na2Li2Ti6O14 was synthesized. All samples prepared by this method are hollow and hierarchical structures with the size of about 2-3 μtm, which are assembled by many prim...Relying on a solvent thermal method, spherical Na2Li2Ti6O14 was synthesized. All samples prepared by this method are hollow and hierarchical structures with the size of about 2-3 μtm, which are assembled by many primary nanoparticles （-300nm）. Particle morphology analysis shows that with the increase of temperature, the porosity increases and the hollow structure becomes more obvious. Na2Li2Ti6Ol4 obtained at 800℃ exhibits the best electro- chemical performance among all samples. Charge-discharge results show that Na2Li2Ti6O14 prepared at 800℃ can delivers a reversible capacity of 220.1, 181.7, 161.6, 144.2, 118.1 and 97.2 mA h g-1 at 50, 140, 280, 560, 1400, 2800 mA g-1. How- ever, Na2Li2Ti6O4-bulk only delivers a reversible capacity of 187, 125.3, 108.3, 88.7, 69.2 and 54.8 mA h g-1 at the same current densities. The high electrochemical performances of the as-prepared materials can be attributed to the distinctive hollow and hierarchical spheres, which could effectively reduce the diffusion distance of Li ions, increase the con- tact area between electrodes and electrolyte, and buffer the volume changes during Li ion intercalation/deintercalation processes.展开更多
OBJECTIVE: To evaluate the effect on acne vulgaris of pricking-bloodletting cupping at Dazhui(GV 14) under acupuncture anesthesia, and establish whether providing anesthesia to the treatment area by manipulating Hegu(...OBJECTIVE: To evaluate the effect on acne vulgaris of pricking-bloodletting cupping at Dazhui(GV 14) under acupuncture anesthesia, and establish whether providing anesthesia to the treatment area by manipulating Hegu(LI 4) and Quchi(LI 11) might have an additional therapeutic benefit. METHODS: Thirty-eight patients were recruited and randomized into a control group and an intervention group with a single-blind(observer-blind) method. The control group was treated by pricking-bloodletting cupping at Dazhui(GV 14) and the studied group by pricking-bloodletting cupping at Dazhui(GV 14) under acupuncture anesthesia at Hegu(LI 4) and Quchi(LI 11). Both groups were treated twice weekly for 6 weeks. The analgesic and therapeutic effects of acupuncture were evaluated on a visual analog scale(VAS) and global acne grading system(GAGS), respectively.RESULTS: There were differences in the VAS scores of pain on pricking and in the pricked area, and the duration of pain between the groups. After 12 treatments, there was a significant reduction in GAGS scores from baseline in both groups, but there was no significant difference between the groups. CONCLUSION: Acupuncture anesthesia at Hegu(LI 4) and Quchi(LI 11) is an effective means of alleviating the pain of pricking-bloodletting cupping and reducing the duration of pain in the treatment area. Pricking-bloodletting cupping at Dazhui(GV 14) improves the skin lesions of patients with moderate acne vulgaris, but acupuncture anesthesia does not appear to have an additional therapeutic effect.展开更多
文摘采用高温固相法成功合成了新型钛基负极材料Na_2Li_2Ti_6O_(14),并研究了其结构及电化学性能。利用高分辨透明电镜(HRTEM)、X射线衍射(XRD)及其Rietveld精修、扫描电子显微镜(SEM)及能谱分析(EDS)表征分析了材料的物相和显微结构。结果表明,合成的Na_2Li_2Ti_6O_(14)负极材料为纯相,具有Fmmm空间群结构;Na_2Li_2Ti_6O_(14)颗粒约为500~800 nm,Na、Ti和O三种元素分布均匀。循环伏安(CV)、充放电及电化学阻抗谱(EIS)测试表明,材料具有较好的锂离子脱嵌可逆性,较好的倍率性能和循环稳定性。钛电流密度为500 m A/g充放电时,Na_2Li_2Ti_6O_(14)材料的首次脱锂(充电)容量为180 m A·h/g,100次循环后可逆容量为136 m A·h/g;100次循环后,Na_2Li_2Ti_6O_(14)材料的电荷转移电阻增加,锂离子扩散系数略有下降,表明Na_2Li_2Ti_6O_(14)材料在循环后SEI膜的生成,降低了材料的电化学活性。
基金supported by the National Natural Science Foundation of China(51404002)Anhui Provincial Natural Science Foundation(1508085MB25)+1 种基金the Natural Science Foundation of Guangdong Province(2016A030310127)Anhui Provincial Science Fund for Excellent Young Scholars(gxyq ZD2016066)
文摘A series of Ba Li_（2-x）NaxTi_6O_（14）（0≤x≤2） compounds as lithium storage materials were synthesized by a facile solidstate method. X-ray diffraction Rietveld refinement shows that the Bragg positions correspond to the Ba Li_2Ti_6O_（14）, indicating a successful preparation. The Na＋ions doped Ba Li_2-Ti_6O_（14） compounds have larger unit-cell volume than the pristine one because ionic radius of Na＋ion is 55% larger than that of Li＋ion. SEM shows that the Ba Li_2-xNaxTi_6O_（14）（x=0, 0.5 and1） powders show similar irregular shaped particles between500 and 1000 nm. However, Ba Li_2-xNaxTi_6O_（14）（x=1.5 and 2）powders show similar rod-like shape. CV reveals that the passivating film is mainly formed during the first insertion process, and the solid electrolyte interface film on the surface of Ba Li_2-xNaxTi_6O_（14）（0≤x≤2） is formed below 0.7 V in the first cycle. Compared with other samples, Ba Li_0.5Na1.5Ti_6O_（14） exhibits higher reversible capacity, better rate capability and superior cyclability. Ba Li_0.5Na1.5Ti_6O_（14） delivers the delithiation capacities of 162.1 mAhg^-（1）at 50 m A g^-（1）, 158.1 mAhg^-（1）at 100 m A g^-（1）, 156.7 mAhg^-（1）at 150 m A g^-（1）, 152.2 mAhg^-（1）at 200 m A g^-（1）, 147.3 mAhg^-（1）at 250 m A g^-（1）and 142 mAhg^-（1）at 300 m A g^-（1）, respectively. An interesting thing is that Ba Na2Ti_6O_（14） as anode also shows an acceptable electrochemical performance. All these improved electrochemical performances of Ba Li_0.5Na1.5Ti_6O_（14） are attributed to the lowest polarization and the highest lithium ion diffusion coefficient among all samples.Hence, Ba Li_0.5Na1.5Ti_6O_（14） with excellent cycling performance,simple synthesis route and wide discharge voltage range can be a possible anode candidate for lithium-ion batteries.
基金supported by the National Natural Science Foundation of China (21301052 and 51404002)Natural Science Foundation of Heilongjiang Province (E2016056)+2 种基金Specialized Research Fund for the Doctoral Program of Higher Education (20132301120001)Postdoctoral Science-Research Developmental Foundation of Heilongjiang Province (LBH-Q13138)Applied Technology Research and Development Program of Harbin (2015RAQXJ032)
文摘Relying on a solvent thermal method, spherical Na2Li2Ti6O14 was synthesized. All samples prepared by this method are hollow and hierarchical structures with the size of about 2-3 μtm, which are assembled by many primary nanoparticles （-300nm）. Particle morphology analysis shows that with the increase of temperature, the porosity increases and the hollow structure becomes more obvious. Na2Li2Ti6Ol4 obtained at 800℃ exhibits the best electro- chemical performance among all samples. Charge-discharge results show that Na2Li2Ti6O14 prepared at 800℃ can delivers a reversible capacity of 220.1, 181.7, 161.6, 144.2, 118.1 and 97.2 mA h g-1 at 50, 140, 280, 560, 1400, 2800 mA g-1. How- ever, Na2Li2Ti6O4-bulk only delivers a reversible capacity of 187, 125.3, 108.3, 88.7, 69.2 and 54.8 mA h g-1 at the same current densities. The high electrochemical performances of the as-prepared materials can be attributed to the distinctive hollow and hierarchical spheres, which could effectively reduce the diffusion distance of Li ions, increase the con- tact area between electrodes and electrolyte, and buffer the volume changes during Li ion intercalation/deintercalation processes.
基金Supported by the New Technique and Occupation Project of General Hospital of Ningxia Medical University(No.2011-2-20)
文摘OBJECTIVE: To evaluate the effect on acne vulgaris of pricking-bloodletting cupping at Dazhui(GV 14) under acupuncture anesthesia, and establish whether providing anesthesia to the treatment area by manipulating Hegu(LI 4) and Quchi(LI 11) might have an additional therapeutic benefit. METHODS: Thirty-eight patients were recruited and randomized into a control group and an intervention group with a single-blind(observer-blind) method. The control group was treated by pricking-bloodletting cupping at Dazhui(GV 14) and the studied group by pricking-bloodletting cupping at Dazhui(GV 14) under acupuncture anesthesia at Hegu(LI 4) and Quchi(LI 11). Both groups were treated twice weekly for 6 weeks. The analgesic and therapeutic effects of acupuncture were evaluated on a visual analog scale(VAS) and global acne grading system(GAGS), respectively.RESULTS: There were differences in the VAS scores of pain on pricking and in the pricked area, and the duration of pain between the groups. After 12 treatments, there was a significant reduction in GAGS scores from baseline in both groups, but there was no significant difference between the groups. CONCLUSION: Acupuncture anesthesia at Hegu(LI 4) and Quchi(LI 11) is an effective means of alleviating the pain of pricking-bloodletting cupping and reducing the duration of pain in the treatment area. Pricking-bloodletting cupping at Dazhui(GV 14) improves the skin lesions of patients with moderate acne vulgaris, but acupuncture anesthesia does not appear to have an additional therapeutic effect.
