The SnCo1-xFex/C （x=0.1, 0.2, 0.3, 0.4） composites as novel anode materials for lithium-ion batteries with large capacity were prepared by ball milling first and then solid-state sintering. The influences of the par...The SnCo1-xFex/C （x=0.1, 0.2, 0.3, 0.4） composites as novel anode materials for lithium-ion batteries with large capacity were prepared by ball milling first and then solid-state sintering. The influences of the partial substitution of inert metal Fe for Co on material structures and the electrochemical properties were investigated. Structure analyses show that the uniform solid dissolution of Fe into CoSn phase promotes the formation of CoSn2 impurity phase. With the growth of x, the cell volumes of CoSn phase is enlarged, the grain size decreases and the content of CoSn2 increases. Carbon black is mainly physically mixed with other phases on the surface of particles. Electrochemical analyses reveal that the reversible capacity and cycle performance are both improved through the introduction of Fe. When x is 0.2, the cycle performance is up to the maximum, 85.1% of the reversible capacity after 50 cycles. During cycling, among SnCo/C, SnCo0.8Fe0.2/C and SnCo0.6Fe0.4/C samples, the grain size of CoSn phase for SnCo0.8Fe0.2/C sample increases leastly. It is usually believed that the comprehensive effects of grain size, structure stability and impurity-phase content lead to the maximum of the cycle performance at appropriate content of Fe （x=0.2）.展开更多
Sn Co alloy nanowires were successfully electrodeposited from Sn Cl2-Co Cl2-1-ethyl-3-methylimidazolium chloride(EMIC) ionic liquid without a template. The nanowires were obtained from the molar ratio of 5:40:60 for S...Sn Co alloy nanowires were successfully electrodeposited from Sn Cl2-Co Cl2-1-ethyl-3-methylimidazolium chloride(EMIC) ionic liquid without a template. The nanowires were obtained from the molar ratio of 5:40:60 for Sn Cl2(25)Co Cl2(25)EMIC at-0.55 V and showed a minimum diameter of about 50 nm and lengths of over 20 μm. The as-fabricated SnCo nanowires were about 70 nm in diameter and featured a Sn/Co weight ratio of 3.85:1, when used as an anode for a Li-ion battery, they presented respective specific capacities of 687 and 678 m Ah·g^(-1) after the first charge and discharge cycle and maintained capacities of about 654 m Ah·g^(-1) after 60 cycles and 539 m Ah·g^(-1) after 80 cycles at a current density of 300 m A·g^(-1). Both the nanowire structure and presence of elemental Co helped buffer large volume changes in the Sn anode during charging and discharging to a certain extent, thereby improving the cycling performance of the Sn anode.展开更多
Catalysts for the oxygen reduction reaction （ORR） play an important role in fuel cells. Alternative non-precious metal catalysts with comparable ORR activity to Pt-based catalysts are highly desirable for the develo...Catalysts for the oxygen reduction reaction （ORR） play an important role in fuel cells. Alternative non-precious metal catalysts with comparable ORR activity to Pt-based catalysts are highly desirable for the development of fuel cells. In this work, we report for the first time a spinel MnC0204/C ORR catalyst consisting of uniform MnC0204 nanoparticles cross-linked with two-dimensional （2D） porous carbon nanosheets （abbreviated as porous MnC0204/C nanosheets）, in which glucose is used as the carbon source and NaC1 as the template. The obtained porous MnCo204/C nanosheets present the combined properties of an interconnected porous architecture and a large surface area （175.3 m2-g-1）, as well as good electrical conductivity （1.15 x 102 S.cm-1）. Thus, the as-prepared MnC0204/C nanosheets efficiently facilitate electrolyte diffusion and offer an expedite transport path for reactants and electrons during the ORR. As a result, the as-prepared porous MnC0204/C nanosheet catalyst exhibits enhanced ORR activity with a higher onset potential and current density than those of its counterparts, including pure MnC0204, carbon nanosheets, and Vulcan XC-72R carbon. More importantly, the porous MnC0204/C nanosheets exhibit a com- parable electrocatalytic activity but superior stability and tolerance toward methanol crossover effects than a high-performance Pt/C catalyst in alkaline medium. The synthetic strategy outlined here can be extended to other non- precious metal catalysts for application in electrochemical energy conversion.展开更多
基金supported by the Natural ScienceFoundation of Liaoning Province(No.20072206)
文摘The SnCo1-xFex/C （x=0.1, 0.2, 0.3, 0.4） composites as novel anode materials for lithium-ion batteries with large capacity were prepared by ball milling first and then solid-state sintering. The influences of the partial substitution of inert metal Fe for Co on material structures and the electrochemical properties were investigated. Structure analyses show that the uniform solid dissolution of Fe into CoSn phase promotes the formation of CoSn2 impurity phase. With the growth of x, the cell volumes of CoSn phase is enlarged, the grain size decreases and the content of CoSn2 increases. Carbon black is mainly physically mixed with other phases on the surface of particles. Electrochemical analyses reveal that the reversible capacity and cycle performance are both improved through the introduction of Fe. When x is 0.2, the cycle performance is up to the maximum, 85.1% of the reversible capacity after 50 cycles. During cycling, among SnCo/C, SnCo0.8Fe0.2/C and SnCo0.6Fe0.4/C samples, the grain size of CoSn phase for SnCo0.8Fe0.2/C sample increases leastly. It is usually believed that the comprehensive effects of grain size, structure stability and impurity-phase content lead to the maximum of the cycle performance at appropriate content of Fe （x=0.2）.
基金financially supported by the National Natural Science Foundation of China(No.51474107)the Opening Project Fund of Key Laboratory of Common Associated Non-ferrous Metal Resources Pressure Hydrometallurgy Technology(No.yy2016008)
文摘Sn Co alloy nanowires were successfully electrodeposited from Sn Cl2-Co Cl2-1-ethyl-3-methylimidazolium chloride(EMIC) ionic liquid without a template. The nanowires were obtained from the molar ratio of 5:40:60 for Sn Cl2(25)Co Cl2(25)EMIC at-0.55 V and showed a minimum diameter of about 50 nm and lengths of over 20 μm. The as-fabricated SnCo nanowires were about 70 nm in diameter and featured a Sn/Co weight ratio of 3.85:1, when used as an anode for a Li-ion battery, they presented respective specific capacities of 687 and 678 m Ah·g^(-1) after the first charge and discharge cycle and maintained capacities of about 654 m Ah·g^(-1) after 60 cycles and 539 m Ah·g^(-1) after 80 cycles at a current density of 300 m A·g^(-1). Both the nanowire structure and presence of elemental Co helped buffer large volume changes in the Sn anode during charging and discharging to a certain extent, thereby improving the cycling performance of the Sn anode.
基金The authors acknowledge the National Natural Science Foundation of China （Nos. 21576139, 21503111, 21376122, and 21273116）, Jiangsu Provincial Natural Science Foundation of Jiangsu Province （No. BK20140926）, Specialized Research Fund for the Doctoral Program of Higher Education （No. 20130202120010）, the Key Science and Technology Program of Shaanxi Province, China （No. 2014K10-06）, Fundamental Research Funds for the Central Universities （No. GK201503038）, China Scholarship Council （CSC, 201506860013）, University Postgraduate Research and Innovation Project in Jiangsu Province （No. KYZZ15_0213）, National and Local Joint Engineering Research Center of Biomedical Functional Material, and a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions. The authors also thank John B. Goodenough of the university of Texas at Austin for his support and help.
文摘Catalysts for the oxygen reduction reaction （ORR） play an important role in fuel cells. Alternative non-precious metal catalysts with comparable ORR activity to Pt-based catalysts are highly desirable for the development of fuel cells. In this work, we report for the first time a spinel MnC0204/C ORR catalyst consisting of uniform MnC0204 nanoparticles cross-linked with two-dimensional （2D） porous carbon nanosheets （abbreviated as porous MnC0204/C nanosheets）, in which glucose is used as the carbon source and NaC1 as the template. The obtained porous MnCo204/C nanosheets present the combined properties of an interconnected porous architecture and a large surface area （175.3 m2-g-1）, as well as good electrical conductivity （1.15 x 102 S.cm-1）. Thus, the as-prepared MnC0204/C nanosheets efficiently facilitate electrolyte diffusion and offer an expedite transport path for reactants and electrons during the ORR. As a result, the as-prepared porous MnC0204/C nanosheet catalyst exhibits enhanced ORR activity with a higher onset potential and current density than those of its counterparts, including pure MnC0204, carbon nanosheets, and Vulcan XC-72R carbon. More importantly, the porous MnC0204/C nanosheets exhibit a com- parable electrocatalytic activity but superior stability and tolerance toward methanol crossover effects than a high-performance Pt/C catalyst in alkaline medium. The synthetic strategy outlined here can be extended to other non- precious metal catalysts for application in electrochemical energy conversion.
