Safety is important to lithium ion battery materials. The thermal stability of LiFePO_4/C-LiMn_2O_4 blended cathode materials is characterized by using TG, XRD, and SEM etc. The results show that LiFePO_4/C-LiMn_2O_4 ...Safety is important to lithium ion battery materials. The thermal stability of LiFePO_4/C-LiMn_2O_4 blended cathode materials is characterized by using TG, XRD, and SEM etc. The results show that LiFePO_4/C-LiMn_2O_4 possesses a worse thermal stability than pure spinel LiMn_2O_4 and pure olivine LiFePO_4/C. When LiFePO_4/C-LiMn_2O_4 blended cathode materials are sintered at 500°C under Ar atmosphere, the sintered cathode materials emit O_2, and appear impurity phases(Li_3PO_4, Fe_2O_3, Mn_3O_4). It is deduced that some chemical reactions take place between different materials, which leads to a worse discharge specific capacity. LiFePO_4/C-LiMn_2O_4 blended cathode materials, therefore, need to be managed and controlled strictly for the sake of thermal stability and safety.展开更多
为研究激光直接物标标识技术(laser direct part marking, DPM)对铝合金2024力学性能的影响,对标识后的铝合金2024进行了标识深度测量、显微硬度检测、静力学拉伸和高周疲劳试验。研究结果表明:不同工艺参数下的标识深度相差很大,深度范...为研究激光直接物标标识技术(laser direct part marking, DPM)对铝合金2024力学性能的影响,对标识后的铝合金2024进行了标识深度测量、显微硬度检测、静力学拉伸和高周疲劳试验。研究结果表明:不同工艺参数下的标识深度相差很大,深度范围5.26~525.7μm;在标识区域会形成重熔区,显微硬度51~62 HV,明显小于材料基体显微硬度值;标识深度会对铝合金2024的抗拉性能和疲劳性能造成影响,在一定标识深度下,标识后的铝合金2024的拉伸性能和疲劳性能满足材料的性能要求。展开更多
The olivine-type structure LiFe_(0.65)Mn_(0.35)PO_4 materials are respectively synthesized via MnO_2 and MnC_2 O_4·2 H_2 O as manganese resources by using solid-state reaction. The compound materials are characte...The olivine-type structure LiFe_(0.65)Mn_(0.35)PO_4 materials are respectively synthesized via MnO_2 and MnC_2 O_4·2 H_2 O as manganese resources by using solid-state reaction. The compound materials are characterized by scanning electron microscopies(SEM),transmission electron microscopy(TEM), X-ray photoelectronspectroscopy(XPS) and electrochemical test. The experimental results demonstrate that LiFe_(0.65)Mn_(0.35)PO_4 prepared by MnO_2 as manganese resource exhibits uniform particles with porous structure in SEM and TEM images. XPS data show the coexistence of Mn^(4+), Mn^(3+) and Mn^(2+) cations. Besides, this sample shows better discharge special capacity of 107.46 mA h g^(-1) at 5 C and capacitance conservation rate about 95.47% after 100 cycles at1 C. The superior electrochemical capability is attributed to the coexistence of mixed-valence manganese cations in crystal and the uniform particles with porous structure.展开更多
基金supported by National Natural Science Foundation of China(Grant No.51364021)Natural Science Foundation of Yunnan Province(Grant No.2014FA025)+1 种基金Innovative Research Team in University of Ministry of Education of China(Grant No.IRT1250)Academician free exploration project of Yunnan Province(Grant No.14051600)
文摘Safety is important to lithium ion battery materials. The thermal stability of LiFePO_4/C-LiMn_2O_4 blended cathode materials is characterized by using TG, XRD, and SEM etc. The results show that LiFePO_4/C-LiMn_2O_4 possesses a worse thermal stability than pure spinel LiMn_2O_4 and pure olivine LiFePO_4/C. When LiFePO_4/C-LiMn_2O_4 blended cathode materials are sintered at 500°C under Ar atmosphere, the sintered cathode materials emit O_2, and appear impurity phases(Li_3PO_4, Fe_2O_3, Mn_3O_4). It is deduced that some chemical reactions take place between different materials, which leads to a worse discharge specific capacity. LiFePO_4/C-LiMn_2O_4 blended cathode materials, therefore, need to be managed and controlled strictly for the sake of thermal stability and safety.
文摘为研究激光直接物标标识技术(laser direct part marking, DPM)对铝合金2024力学性能的影响,对标识后的铝合金2024进行了标识深度测量、显微硬度检测、静力学拉伸和高周疲劳试验。研究结果表明:不同工艺参数下的标识深度相差很大,深度范围5.26~525.7μm;在标识区域会形成重熔区,显微硬度51~62 HV,明显小于材料基体显微硬度值;标识深度会对铝合金2024的抗拉性能和疲劳性能造成影响,在一定标识深度下,标识后的铝合金2024的拉伸性能和疲劳性能满足材料的性能要求。
基金supported by the National Natural Science Foundation of China(Grant No.51364021)the Natural Science Foundation of Yunnan Province(Grant No.2014FA025)+1 种基金Innovative Research Team in University of Ministry of Education of China(Grant No.IRT1250)Academician Free Exploration Project of Yunnan Province(Grant No.14051600)
文摘The olivine-type structure LiFe_(0.65)Mn_(0.35)PO_4 materials are respectively synthesized via MnO_2 and MnC_2 O_4·2 H_2 O as manganese resources by using solid-state reaction. The compound materials are characterized by scanning electron microscopies(SEM),transmission electron microscopy(TEM), X-ray photoelectronspectroscopy(XPS) and electrochemical test. The experimental results demonstrate that LiFe_(0.65)Mn_(0.35)PO_4 prepared by MnO_2 as manganese resource exhibits uniform particles with porous structure in SEM and TEM images. XPS data show the coexistence of Mn^(4+), Mn^(3+) and Mn^(2+) cations. Besides, this sample shows better discharge special capacity of 107.46 mA h g^(-1) at 5 C and capacitance conservation rate about 95.47% after 100 cycles at1 C. The superior electrochemical capability is attributed to the coexistence of mixed-valence manganese cations in crystal and the uniform particles with porous structure.
