A 3D structured composite of carbon nanofibers @ MnO2 on copper foil is reported here as a binder free anode of lithium ion batteries, with high capacity, fast charge/discharge rate and good stability. Carbon nanofibe...A 3D structured composite of carbon nanofibers @ MnO2 on copper foil is reported here as a binder free anode of lithium ion batteries, with high capacity, fast charge/discharge rate and good stability. Carbon nanofiber yarns were synthesized directly over copper foil through a floating catalyst method. The growth of carbon nanofiber yarns was significantly enhanced by mechanical polishing of the copper foils, which can be attributed to the increased surface roughness and surface area of the copper foils. MnO2 was then grown over carbon nanofibers through spontaneous reduction of potassium permanganate by the carbon nanofibers. The obtained composites of carbon nanofibers@MnO2 over copper foil were tested as an anode in lithium ion batteries and they show superior electrochemical performance. The initial reversible capacity of carbon nanofibers@MnO2 reaches up to around 998 mAh.g-1 at a rate of 60 mmA.g-l based on the mass of carbon nanofibers and MnO2. The carbon nanofibers @ MnO2 electrodes could deliver a capacity of 630 mAh.g-1 at the beginning and maintain a capacity of 440 mmAh.g-1 after 105 cycles at a rate of 600 mA.g-~. The high initial capacity can be attributed to the presence of porous carbon nanofiber yarns which have good electrical conductivity and the MnO2 thin film which makes the entire materials electrochemically active. The high cyclic stability of carbon nanofibers@MnO2 can be ascribed to the MnO2 thin film which can accommodate the volume expansion and shrinking during charge and discharge and the good contact of carbon nanofibers with MnO2 and copper foil.展开更多
分别采用氢氧化物共沉淀、碳酸盐共沉淀、喷雾干燥的方法合成了层状α-Na Fe O2结构的富锂正极材料0.5Li2Mn O3·0.5Li(Ni1/3Co1/3Mn1/3)O2,通过X射线衍射分析(XRD)、扫描电子显微镜(SEM)和电化学性能测试对不同合成方法所得的样品...分别采用氢氧化物共沉淀、碳酸盐共沉淀、喷雾干燥的方法合成了层状α-Na Fe O2结构的富锂正极材料0.5Li2Mn O3·0.5Li(Ni1/3Co1/3Mn1/3)O2,通过X射线衍射分析(XRD)、扫描电子显微镜(SEM)和电化学性能测试对不同合成方法所得的样品进行了表征。实验结果表明:氢氧化物共沉淀合成的前驱体所制备的正极材料0.5Li2Mn O3·0.5Li(Ni1/3Co1/3Mn1/3)O2具有良好的电化学性能,0.05C倍率下首次放电容量可达247.1 m A·h/g,0.2C倍率条件下经过50次循环,容量保持率为98.7%。展开更多
Lithium-ion batteries (LIBs) with high energy density have attracted great attention for their wide applications in electric vehicles, and the exploration of the nextgeneration anode materials with high theoretical ca...Lithium-ion batteries (LIBs) with high energy density have attracted great attention for their wide applications in electric vehicles, and the exploration of the nextgeneration anode materials with high theoretical capacity is highly desired. In this work, Sn02 nanoparticles with the particle size of 200 nm uniformly anchored on the surface of graphene oxide (GO) was prepared by combination of the ultrasonic method and the following calcination process. The Sn02/GO composite with the weight ratio of Sn02 to GO at 4:1 exhibits excellent electrochemical performance, which originates from the synergistic effects between GO and Sn02 nanoparticles. A high discharge capacity of 492 mA·h·g^-1 can be obtained after 100 cycles at 0.2C, and after cycling at higher current densities of 1C and 2C, a discharge capacity of 641 mA·h·g^-1 can be restored when the current density goes back to 0.1C. The superior electrochemical performance and simple synthesis process make it a very promising candidate as anode materials for LIBs.展开更多
Spherical Li(Ni_(1/3)Mn_(1/3)Co_(1/3))O_2 was prepared via the homogenous precursors produced by solution spray-drying method. The precursors were sintered at different temperatures between 600 and 1 000 ℃ for 10 h. ...Spherical Li(Ni_(1/3)Mn_(1/3)Co_(1/3))O_2 was prepared via the homogenous precursors produced by solution spray-drying method. The precursors were sintered at different temperatures between 600 and 1 000 ℃ for 10 h. The impacts of different sintering temperatures on the structure and electrochemical performances of Li(Ni_(1/3)Mn_(1/3)Co_(1/3))O_2 were compared by means of X-ray diffractometry(XRD), scanning electron microscopy(SEM), and charge/discharge test as cathode materials for lithium ion batteries. The experimental results show that the spherical morphology of the spray-dried powers maintains during the subsequent heat treatment and the specific capacity increases with rising sintering temperature. When the sintering temperature rises up to 900 ℃ , Li(Ni_(1/3)Mn_(1/3)Co_(1/3))O_2 attains a reversible capacity of 153 mA·h/g between 3.00 and 4.35 V at 0.2C rate with excellent cyclability.展开更多
Aqueous zinc-ion batteries,especially Zn-Mn02 battery,have attracted intensive attention owing to their unique features of high capacity,environmental friendliness,and safety.However,the problem of Mn dissolution hind...Aqueous zinc-ion batteries,especially Zn-Mn02 battery,have attracted intensive attention owing to their unique features of high capacity,environmental friendliness,and safety.However,the problem of Mn dissolution hinders the development of zinc-ion batteries with long-term usage and high-rate performance.In this work,a novel preparation method for the polyaniline(PANI)-coated composite aerogel of Mn02 and rGO(MnO2/rGO/PANI)electrode is reported.The obtained composite possesses high electrical conductivity,and also effectively suppresses the dissolution of Mn.The fabricated Mn02/rGO/PANI//Zn battery exhibits a high capacity of 241.1 mAh·g^-1 at 0.1 A·g^-1,and an excellent capacity retention of 82.7%after 600 charge/discharge cycles.In addition,the rapid diffusion coefficient of the Mn02/rGO/PANI electrode was further examined by galvanostatic intermittent titration technique.This work provides new insights into the development of high-performance Zn-Mn02 battery with a better understanding of its diffusion kinetics.展开更多
Mixtures of NaHSO4·H2O and LiCoO2 extracted from spent lithium-ion batteries were prepared with molar ratios of 1：1, 1：2 and 1：3. The chemical evolution of the LiCoO2 and NaHSO4-H20 mixtures during the roastin...Mixtures of NaHSO4·H2O and LiCoO2 extracted from spent lithium-ion batteries were prepared with molar ratios of 1：1, 1：2 and 1：3. The chemical evolution of the LiCoO2 and NaHSO4-H20 mixtures during the roasting process was investigated by means of thermogravimetric analysis and differential scanning calorimetry （TG-DSC）, X-ray diffraction（XRD）, scanning electron （XPS）. The results show that the chemical reactions in microscopy（SEM）, and X-ray photoelectron spectroscopy the LiCoO2 and NaHSO4·H2O mixtures proceed during the roasting process. The Li element in the product of the roasting process is in the form of LiNa（SO4）. With the increase of the proportion of NaHSO4·H2O in the mixtures, the Co element evolves as follows： LiCoO2→Co3O4→Na6Co（SOa）4→Na2Co（SO4）2. The roasting products exhibit dense structures and irregular shapes, and the bonding energy of Co increases.展开更多
基金VISTA-a basic research program funded by Statoil,conducted in close collaboration with The Norwegian Academy of Science and Letters which is gratefully acknowledged
文摘A 3D structured composite of carbon nanofibers @ MnO2 on copper foil is reported here as a binder free anode of lithium ion batteries, with high capacity, fast charge/discharge rate and good stability. Carbon nanofiber yarns were synthesized directly over copper foil through a floating catalyst method. The growth of carbon nanofiber yarns was significantly enhanced by mechanical polishing of the copper foils, which can be attributed to the increased surface roughness and surface area of the copper foils. MnO2 was then grown over carbon nanofibers through spontaneous reduction of potassium permanganate by the carbon nanofibers. The obtained composites of carbon nanofibers@MnO2 over copper foil were tested as an anode in lithium ion batteries and they show superior electrochemical performance. The initial reversible capacity of carbon nanofibers@MnO2 reaches up to around 998 mAh.g-1 at a rate of 60 mmA.g-l based on the mass of carbon nanofibers and MnO2. The carbon nanofibers @ MnO2 electrodes could deliver a capacity of 630 mAh.g-1 at the beginning and maintain a capacity of 440 mmAh.g-1 after 105 cycles at a rate of 600 mA.g-~. The high initial capacity can be attributed to the presence of porous carbon nanofiber yarns which have good electrical conductivity and the MnO2 thin film which makes the entire materials electrochemically active. The high cyclic stability of carbon nanofibers@MnO2 can be ascribed to the MnO2 thin film which can accommodate the volume expansion and shrinking during charge and discharge and the good contact of carbon nanofibers with MnO2 and copper foil.
文摘分别采用氢氧化物共沉淀、碳酸盐共沉淀、喷雾干燥的方法合成了层状α-Na Fe O2结构的富锂正极材料0.5Li2Mn O3·0.5Li(Ni1/3Co1/3Mn1/3)O2,通过X射线衍射分析(XRD)、扫描电子显微镜(SEM)和电化学性能测试对不同合成方法所得的样品进行了表征。实验结果表明:氢氧化物共沉淀合成的前驱体所制备的正极材料0.5Li2Mn O3·0.5Li(Ni1/3Co1/3Mn1/3)O2具有良好的电化学性能,0.05C倍率下首次放电容量可达247.1 m A·h/g,0.2C倍率条件下经过50次循环,容量保持率为98.7%。
基金the financial support from the Natural Science Foundation of Beijing (No. 2162037 and LI 82062)the Beijing Nova Program (Z171100001117077)the Yue Qi Young Scholar Project of China University of Mining & Technology (Beijing)(No. 2017QN17).
文摘Lithium-ion batteries (LIBs) with high energy density have attracted great attention for their wide applications in electric vehicles, and the exploration of the nextgeneration anode materials with high theoretical capacity is highly desired. In this work, Sn02 nanoparticles with the particle size of 200 nm uniformly anchored on the surface of graphene oxide (GO) was prepared by combination of the ultrasonic method and the following calcination process. The Sn02/GO composite with the weight ratio of Sn02 to GO at 4:1 exhibits excellent electrochemical performance, which originates from the synergistic effects between GO and Sn02 nanoparticles. A high discharge capacity of 492 mA·h·g^-1 can be obtained after 100 cycles at 0.2C, and after cycling at higher current densities of 1C and 2C, a discharge capacity of 641 mA·h·g^-1 can be restored when the current density goes back to 0.1C. The superior electrochemical performance and simple synthesis process make it a very promising candidate as anode materials for LIBs.
文摘Spherical Li(Ni_(1/3)Mn_(1/3)Co_(1/3))O_2 was prepared via the homogenous precursors produced by solution spray-drying method. The precursors were sintered at different temperatures between 600 and 1 000 ℃ for 10 h. The impacts of different sintering temperatures on the structure and electrochemical performances of Li(Ni_(1/3)Mn_(1/3)Co_(1/3))O_2 were compared by means of X-ray diffractometry(XRD), scanning electron microscopy(SEM), and charge/discharge test as cathode materials for lithium ion batteries. The experimental results show that the spherical morphology of the spray-dried powers maintains during the subsequent heat treatment and the specific capacity increases with rising sintering temperature. When the sintering temperature rises up to 900 ℃ , Li(Ni_(1/3)Mn_(1/3)Co_(1/3))O_2 attains a reversible capacity of 153 mA·h/g between 3.00 and 4.35 V at 0.2C rate with excellent cyclability.
基金supported by the National Natural Science Foundation of China(Nos.51602284 and 51702286)Natural Science Foundation of Zhejiang Province,China(Nos.LQ17B030002 and LR19E020003)General Scientific Research Project of the Department of Education of Zhejiang Province,China(No.Y201839638).
文摘Aqueous zinc-ion batteries,especially Zn-Mn02 battery,have attracted intensive attention owing to their unique features of high capacity,environmental friendliness,and safety.However,the problem of Mn dissolution hinders the development of zinc-ion batteries with long-term usage and high-rate performance.In this work,a novel preparation method for the polyaniline(PANI)-coated composite aerogel of Mn02 and rGO(MnO2/rGO/PANI)electrode is reported.The obtained composite possesses high electrical conductivity,and also effectively suppresses the dissolution of Mn.The fabricated Mn02/rGO/PANI//Zn battery exhibits a high capacity of 241.1 mAh·g^-1 at 0.1 A·g^-1,and an excellent capacity retention of 82.7%after 600 charge/discharge cycles.In addition,the rapid diffusion coefficient of the Mn02/rGO/PANI electrode was further examined by galvanostatic intermittent titration technique.This work provides new insights into the development of high-performance Zn-Mn02 battery with a better understanding of its diffusion kinetics.
基金Supported by the National Natural Science Foundation of China（No.51264027） and the National Basic Research Program of China（No .2012CB722806）.
文摘Mixtures of NaHSO4·H2O and LiCoO2 extracted from spent lithium-ion batteries were prepared with molar ratios of 1：1, 1：2 and 1：3. The chemical evolution of the LiCoO2 and NaHSO4-H20 mixtures during the roasting process was investigated by means of thermogravimetric analysis and differential scanning calorimetry （TG-DSC）, X-ray diffraction（XRD）, scanning electron （XPS）. The results show that the chemical reactions in microscopy（SEM）, and X-ray photoelectron spectroscopy the LiCoO2 and NaHSO4·H2O mixtures proceed during the roasting process. The Li element in the product of the roasting process is in the form of LiNa（SO4）. With the increase of the proportion of NaHSO4·H2O in the mixtures, the Co element evolves as follows： LiCoO2→Co3O4→Na6Co（SOa）4→Na2Co（SO4）2. The roasting products exhibit dense structures and irregular shapes, and the bonding energy of Co increases.
