A series of Co-Sn alloys with Sn content ranging from 12% to 32%（mole fraction） were undercooled to different degrees below the equilibrium liquidus temperature and the solidification behaviors were investigated by ...A series of Co-Sn alloys with Sn content ranging from 12% to 32%（mole fraction） were undercooled to different degrees below the equilibrium liquidus temperature and the solidification behaviors were investigated by monitoring the temperature recalescence and examing the solidification microstructures.A boundary clearly exists,which separates the coupled growth zone from the decoupled growth zone of eutectic phases for the alloys with Sn content ranging from 14% to 31%（mole fraction）.The other Co-Sn alloys out of this content range are hard to be undercooled into the coupled growth zone in the experiment.It is found that the so-called non-reciprocal nucleation phenomenon does not happen in the solidification of undercooled Co-Sn off-eutectic alloys.展开更多
The equilibrium structures, formation energy, mechanical properties and electronic properties of Co-Sn intermetallics have been systemically studied by first-principles study. The results show that the CoSn phase is m...The equilibrium structures, formation energy, mechanical properties and electronic properties of Co-Sn intermetallics have been systemically studied by first-principles study. The results show that the CoSn phase is more thermodynamically stable than any other stoichiometry of Co-Sn intermetallics. With the increasing of Co content in Co-Sn intermetallics, the mechanical properties change into brittle behavior from ductility character. Adding proper amount of Co to Co-Sn intermetallics can improve the cycle performance for lithium ion battery anode. However, high Co content will lead to a poor cycle performance for Co-Sn intermetallics.展开更多
分别以葡萄糖和乙炔黑为碳源,采用固相烧结法制备Sn-Co/C锂离子电池负极复合材料,探讨碳源种类对材料结构和电化学性能的影响规律。结果表明:摩尔比为1:1的Sn-Co合金由Co Sn相和微量Co Sn2相组成;在Sn-Co/C复合材料中,大部分葡萄糖热解...分别以葡萄糖和乙炔黑为碳源,采用固相烧结法制备Sn-Co/C锂离子电池负极复合材料,探讨碳源种类对材料结构和电化学性能的影响规律。结果表明:摩尔比为1:1的Sn-Co合金由Co Sn相和微量Co Sn2相组成;在Sn-Co/C复合材料中,大部分葡萄糖热解炭和乙炔黑存在于Sn-Co合金颗粒表面,少部分进入颗粒内部,会在一定程度上阻碍Sn-Co合金的相变反应,残留微量Co Sn2和Co3Sn2相,同时阻碍Sn-Co合金晶粒或颗粒的长大,起到细化晶粒或颗粒的作用。添加葡萄糖热解炭和乙炔黑有利于提高Sn-Co/C复合材料的电子导电和Li+扩散,从而提高其电化学活性;并且添加葡萄糖的Sn-Co/C复合材料电化学性能更好,在电流密度为0.05 m A/cm2条件下的首次可逆放电容量为325 m A·h/g,经过100次循环后的容量保持率达到70.8%,循环性能比Sn-Co合金的提高26.8%,显示出良好的结构稳定性。展开更多
基金Project(50874073) supported by the National Natural Science Foundation of ChinaProject(2011CB610405) supported by the National Basic Research Program of ChinaProject(2011M500074) supported by China Postdoctoral Science Foundation
文摘A series of Co-Sn alloys with Sn content ranging from 12% to 32%（mole fraction） were undercooled to different degrees below the equilibrium liquidus temperature and the solidification behaviors were investigated by monitoring the temperature recalescence and examing the solidification microstructures.A boundary clearly exists,which separates the coupled growth zone from the decoupled growth zone of eutectic phases for the alloys with Sn content ranging from 14% to 31%（mole fraction）.The other Co-Sn alloys out of this content range are hard to be undercooled into the coupled growth zone in the experiment.It is found that the so-called non-reciprocal nucleation phenomenon does not happen in the solidification of undercooled Co-Sn off-eutectic alloys.
基金Supported by the National Natural Science Foundation of China（Nos.51274119, 51774175） and the Open Projects of Research Center of Coal Resources Safe Mining and Clean Utilization, Liaening Province, China（No. LNTU16KF15）.
文摘The equilibrium structures, formation energy, mechanical properties and electronic properties of Co-Sn intermetallics have been systemically studied by first-principles study. The results show that the CoSn phase is more thermodynamically stable than any other stoichiometry of Co-Sn intermetallics. With the increasing of Co content in Co-Sn intermetallics, the mechanical properties change into brittle behavior from ductility character. Adding proper amount of Co to Co-Sn intermetallics can improve the cycle performance for lithium ion battery anode. However, high Co content will lead to a poor cycle performance for Co-Sn intermetallics.
文摘分别以葡萄糖和乙炔黑为碳源,采用固相烧结法制备Sn-Co/C锂离子电池负极复合材料,探讨碳源种类对材料结构和电化学性能的影响规律。结果表明:摩尔比为1:1的Sn-Co合金由Co Sn相和微量Co Sn2相组成;在Sn-Co/C复合材料中,大部分葡萄糖热解炭和乙炔黑存在于Sn-Co合金颗粒表面,少部分进入颗粒内部,会在一定程度上阻碍Sn-Co合金的相变反应,残留微量Co Sn2和Co3Sn2相,同时阻碍Sn-Co合金晶粒或颗粒的长大,起到细化晶粒或颗粒的作用。添加葡萄糖热解炭和乙炔黑有利于提高Sn-Co/C复合材料的电子导电和Li+扩散,从而提高其电化学活性;并且添加葡萄糖的Sn-Co/C复合材料电化学性能更好,在电流密度为0.05 m A/cm2条件下的首次可逆放电容量为325 m A·h/g,经过100次循环后的容量保持率达到70.8%,循环性能比Sn-Co合金的提高26.8%,显示出良好的结构稳定性。
