Manganese compound with evident toxicity is widely employed as the contrast medium for clinicalexaminations such as magnetic resonance imaging(MRI).In the present work,a feasible way with the applica-tion of vacuum im...Manganese compound with evident toxicity is widely employed as the contrast medium for clinicalexaminations such as magnetic resonance imaging(MRI).In the present work,a feasible way with the applica-tion of vacuum impregnation and rotary evaporation was proposed to introduce manganese chloride hydrate intothe inner cavities of template - synthesized carbon nanotubes(CNTs),and then a process of alkali treatmentwas used to liberate the loaded CNTs from the template.It is notable that the alkali attack in the presence ofresidual oxygen also resulted in a series of changes in chemical compositions of guest substances,and the ulti-mate compound of manganese was found to be manganese oxide(Mn3O4) by X-ray diffraction and transmissionelectron microscopy.Determinations of energy dispersive spectrum under scanning electron microscopy showeda high-content filling(more than 50 wt%) of Mn3O4 in the loaded CNTs.This work developed a feasible andconvenient way for the encapsulation of guest substances to reduce bio-toxic effects.展开更多
Lithium nickel manganese oxide spinel(Li Ni0.5-Mn1.5O4, LNMO) has attracted much attention as the cathode material for rechargeable lithium-ion batteries due to its high energy density and low cost. However, the short...Lithium nickel manganese oxide spinel(Li Ni0.5-Mn1.5O4, LNMO) has attracted much attention as the cathode material for rechargeable lithium-ion batteries due to its high energy density and low cost. However, the short cycle life and poor high-rate capability hinder its commercialization. In this study, we synthesized hollow spherical LNMO built from polyhedral particles. The LNMO hollow structure guarantees sufficient contact with electrolyte and rapid diffusion of lithium ions. To enhance the conductivity, we use carbon nanotubes(CNTs) to modify the surface of the cathode. After CNT modification, the LNMO hollow structure manifests outstanding cycling stability and high-rate capability. It delivers a discharge capacity of 127 m A h g-1 at 5 C, maintaining 104 m A h g-1 after 500 cycles. Even at a high rate of 20 C, a capacity of 121 m A h g-1 can be obtained. The excellent electrochemical performance is ascribed to the unique structure and the enhanced conductivity through CNT modification. It is demonstrated that the CNTmodified hollow spherical LNMO is a promising cathode for lithium ion batteries.展开更多
近年来,具备可穿戴和柔性功能的便携式电子设备备受关注,对提供其能量的储能器件研究也逐渐成为热点。平面超级电容器具有功率密度高、充放电速率快、循环稳定性好、易于集成等优点,是重要的可穿戴和柔性电子产品的潜在电源。在电极材料...近年来,具备可穿戴和柔性功能的便携式电子设备备受关注,对提供其能量的储能器件研究也逐渐成为热点。平面超级电容器具有功率密度高、充放电速率快、循环稳定性好、易于集成等优点,是重要的可穿戴和柔性电子产品的潜在电源。在电极材料中,锰酸锌(ZnMn_(2)O_(4))拥有较高的理论比电容,但存在电导率较差的难题,这影响了其循环稳定性和功率密度。碳纳米管(CNTs)具有优异的长期稳定性和高功率密度,以及较好的电导率,因此可以通过引入CNTs改善ZnMn_(2)O_(4)电导率。微电子打印技术是是一种简便的制备平面超级电容器的新方法。本文采用水热法制备出ZnMn_(2)O_(4)和CNTs复合材料,并且利用微电子打印机中的点胶打印功能,在聚对苯二甲酸乙二醇酯(PET)衬底上制备得到基于ZnMn_(2)O_(4)-CNTs平面超级电容器。结果表明,采用该方法制备得到的ZnMn_(2)O_(4)-CNTs平面超级电容器,由于引入了CNTs,改善了ZnMn_(2)O_(4)的电导率,能展现出更好的性能。在0.023 mA cm^(-2)电流密度下其比电容达到了13.687 mF cm^(-2),在10000圈的循环后,电容保持率高达99.47%,远优于纯ZnMn_(2)O_(4)的电化学性能。展开更多
文摘Manganese compound with evident toxicity is widely employed as the contrast medium for clinicalexaminations such as magnetic resonance imaging(MRI).In the present work,a feasible way with the applica-tion of vacuum impregnation and rotary evaporation was proposed to introduce manganese chloride hydrate intothe inner cavities of template - synthesized carbon nanotubes(CNTs),and then a process of alkali treatmentwas used to liberate the loaded CNTs from the template.It is notable that the alkali attack in the presence ofresidual oxygen also resulted in a series of changes in chemical compositions of guest substances,and the ulti-mate compound of manganese was found to be manganese oxide(Mn3O4) by X-ray diffraction and transmissionelectron microscopy.Determinations of energy dispersive spectrum under scanning electron microscopy showeda high-content filling(more than 50 wt%) of Mn3O4 in the loaded CNTs.This work developed a feasible andconvenient way for the encapsulation of guest substances to reduce bio-toxic effects.
基金supported by the National Basic Research Program of China(2013CB934103 and 2012CB933003)the International Science&Technology Cooperation Program of China(2013DFA50840)+4 种基金the National Natural Science Foundation of China(51521001 and 51272197)the National Natural Science Fund for Distinguished Young Scholars(51425204)Hubei Province Natural Science Fund for Distinguished Young Scholars(2014CFA035)the Fundamental Research Funds for the Central Universities(WUT:2015-III-0322015-III-021)
文摘Lithium nickel manganese oxide spinel(Li Ni0.5-Mn1.5O4, LNMO) has attracted much attention as the cathode material for rechargeable lithium-ion batteries due to its high energy density and low cost. However, the short cycle life and poor high-rate capability hinder its commercialization. In this study, we synthesized hollow spherical LNMO built from polyhedral particles. The LNMO hollow structure guarantees sufficient contact with electrolyte and rapid diffusion of lithium ions. To enhance the conductivity, we use carbon nanotubes(CNTs) to modify the surface of the cathode. After CNT modification, the LNMO hollow structure manifests outstanding cycling stability and high-rate capability. It delivers a discharge capacity of 127 m A h g-1 at 5 C, maintaining 104 m A h g-1 after 500 cycles. Even at a high rate of 20 C, a capacity of 121 m A h g-1 can be obtained. The excellent electrochemical performance is ascribed to the unique structure and the enhanced conductivity through CNT modification. It is demonstrated that the CNTmodified hollow spherical LNMO is a promising cathode for lithium ion batteries.
文摘近年来,具备可穿戴和柔性功能的便携式电子设备备受关注,对提供其能量的储能器件研究也逐渐成为热点。平面超级电容器具有功率密度高、充放电速率快、循环稳定性好、易于集成等优点,是重要的可穿戴和柔性电子产品的潜在电源。在电极材料中,锰酸锌(ZnMn_(2)O_(4))拥有较高的理论比电容,但存在电导率较差的难题,这影响了其循环稳定性和功率密度。碳纳米管(CNTs)具有优异的长期稳定性和高功率密度,以及较好的电导率,因此可以通过引入CNTs改善ZnMn_(2)O_(4)电导率。微电子打印技术是是一种简便的制备平面超级电容器的新方法。本文采用水热法制备出ZnMn_(2)O_(4)和CNTs复合材料,并且利用微电子打印机中的点胶打印功能,在聚对苯二甲酸乙二醇酯(PET)衬底上制备得到基于ZnMn_(2)O_(4)-CNTs平面超级电容器。结果表明,采用该方法制备得到的ZnMn_(2)O_(4)-CNTs平面超级电容器,由于引入了CNTs,改善了ZnMn_(2)O_(4)的电导率,能展现出更好的性能。在0.023 mA cm^(-2)电流密度下其比电容达到了13.687 mF cm^(-2),在10000圈的循环后,电容保持率高达99.47%,远优于纯ZnMn_(2)O_(4)的电化学性能。
