将层状的LiNi1/3Co1/3Mn1/3O2锂离子电池正极材料与尖晶石型的LiMn2O4按质量比为2∶98混合烧结,采用X射线衍射（XRD）、循环伏安法（CV）、交流阻抗（EIS）以及充放电测试研究LiMn2O4对LiNi1/3Co1/3Mn1/3O2电化学性能的影响。研究表明混...将层状的LiNi1/3Co1/3Mn1/3O2锂离子电池正极材料与尖晶石型的LiMn2O4按质量比为2∶98混合烧结,采用X射线衍射（XRD）、循环伏安法（CV）、交流阻抗（EIS）以及充放电测试研究LiMn2O4对LiNi1/3Co1/3Mn1/3O2电化学性能的影响。研究表明混合LiMn2O4有利于提高LiNi1/3Co1/3Mn1/3O2正极材料的首次库仑效率、循环性能和倍率性能,在3.0~4.3 V以1 C循环,首次放电比容量和库仑效率分别为150.3 m Ah/g和85.5%,循环50次后容量保持率为88.9%;在5 C下充放电仍保持136.2 m Ah/g。循环伏安与交流阻抗测试表明混合2%（质量分数）LiMn2O4可以提升材料的可逆性和放电容量,降低电荷转移电阻。展开更多
Layered F-doped cathode materials 0.3 Li_2 MnO_3-0.7 LiMn_(1/3)Ni_(1/3)CO_(1/3))O_(2-x)F_x(x = 0, 0.01, 0.02, 0.03, 0.04,0.05) microspheres made up of nanosized primary grains were prepared through co-precipitation me...Layered F-doped cathode materials 0.3 Li_2 MnO_3-0.7 LiMn_(1/3)Ni_(1/3)CO_(1/3))O_(2-x)F_x(x = 0, 0.01, 0.02, 0.03, 0.04,0.05) microspheres made up of nanosized primary grains were prepared through co-precipitation method. The sample of x = 0.02 demonstrates a large discharge capacity of226 mAh g^(-1) over 100 cycles at 0.1 C and excellent rate performance with discharge capacity of 96 mAh g-1 at 5.0 C and room temperature. Particularly, this material shows much enhanced electrochemical performances even at high temperature of 55 ℃. It delivers a quite high discharge capacity of 233.7 mAh·g^(-1) at 1.0 C with capacity retention as high as 97.9% after 100 cycles. The results demonstrate that the fluorine incorporation stabilizes the cathode structure and maintains stable interfacial resistances.展开更多
Single phase chromium-substituted orthorhombic LiMn1-xCrxO2 （0≤x≤0.05） were successfully synthesized by hydrothermal treatment of Mn2O3, Cr2O3 and lithium hydroxide aqueous solution. Structure and morphologies of ...Single phase chromium-substituted orthorhombic LiMn1-xCrxO2 （0≤x≤0.05） were successfully synthesized by hydrothermal treatment of Mn2O3, Cr2O3 and lithium hydroxide aqueous solution. Structure and morphologies of the o-LiMn1-xCrxO2 were characterized by X-ray diffraction and transmission electron microscopy. Compared to the particle size of o-LiMnO2 ranging from 50 to 150 nm, the Cr-doped one is larger with about 500 nm, which is agglomerated by small grains. There are high stacking faults in nanosized grains that cause easier phase transformation from the orthorhombic to the spinel-like structure on cycling. High-resolution transmission electron microscopy image analysis of electrochemically cycled o-LiMn1-xCrxO2 （x=0, 0.05） samples showed that the nanodomain structure in o-LiMn0.95Cr0.05O2 was comparatively perfect to that in o-LiMnO2. Particle agglomeration and the relatively perfect crystal structure are two key factors for improving cycle performance of o-LiMn0.95Cr0.05O2. The obtained o-LiMn0.95Cr0.05O2 can reach a maximum discharge capacity of 174 mA·h·g^-1 at 0.1 C rate in seventh cycle. The discharge capacity fade rate of the samples decreased with increasing Cr amount. Furthermore, o-LiMn0.95Cr0.05O2 gives a highest discharge capacity of 150 mA·h·g^-1 at a high current rate of 0.5 C, and retains 130 mA·h·g^-1 after 40 cycles.展开更多
文摘将层状的LiNi1/3Co1/3Mn1/3O2锂离子电池正极材料与尖晶石型的LiMn2O4按质量比为2∶98混合烧结,采用X射线衍射（XRD）、循环伏安法（CV）、交流阻抗（EIS）以及充放电测试研究LiMn2O4对LiNi1/3Co1/3Mn1/3O2电化学性能的影响。研究表明混合LiMn2O4有利于提高LiNi1/3Co1/3Mn1/3O2正极材料的首次库仑效率、循环性能和倍率性能,在3.0~4.3 V以1 C循环,首次放电比容量和库仑效率分别为150.3 m Ah/g和85.5%,循环50次后容量保持率为88.9%;在5 C下充放电仍保持136.2 m Ah/g。循环伏安与交流阻抗测试表明混合2%（质量分数）LiMn2O4可以提升材料的可逆性和放电容量,降低电荷转移电阻。
基金financially supported by the National Natural Science Foundation of China (No. 51372136)the NSFC-Guangdong United Fund (No. U1401246)
文摘Layered F-doped cathode materials 0.3 Li_2 MnO_3-0.7 LiMn_(1/3)Ni_(1/3)CO_(1/3))O_(2-x)F_x(x = 0, 0.01, 0.02, 0.03, 0.04,0.05) microspheres made up of nanosized primary grains were prepared through co-precipitation method. The sample of x = 0.02 demonstrates a large discharge capacity of226 mAh g^(-1) over 100 cycles at 0.1 C and excellent rate performance with discharge capacity of 96 mAh g-1 at 5.0 C and room temperature. Particularly, this material shows much enhanced electrochemical performances even at high temperature of 55 ℃. It delivers a quite high discharge capacity of 233.7 mAh·g^(-1) at 1.0 C with capacity retention as high as 97.9% after 100 cycles. The results demonstrate that the fluorine incorporation stabilizes the cathode structure and maintains stable interfacial resistances.
文摘Single phase chromium-substituted orthorhombic LiMn1-xCrxO2 （0≤x≤0.05） were successfully synthesized by hydrothermal treatment of Mn2O3, Cr2O3 and lithium hydroxide aqueous solution. Structure and morphologies of the o-LiMn1-xCrxO2 were characterized by X-ray diffraction and transmission electron microscopy. Compared to the particle size of o-LiMnO2 ranging from 50 to 150 nm, the Cr-doped one is larger with about 500 nm, which is agglomerated by small grains. There are high stacking faults in nanosized grains that cause easier phase transformation from the orthorhombic to the spinel-like structure on cycling. High-resolution transmission electron microscopy image analysis of electrochemically cycled o-LiMn1-xCrxO2 （x=0, 0.05） samples showed that the nanodomain structure in o-LiMn0.95Cr0.05O2 was comparatively perfect to that in o-LiMnO2. Particle agglomeration and the relatively perfect crystal structure are two key factors for improving cycle performance of o-LiMn0.95Cr0.05O2. The obtained o-LiMn0.95Cr0.05O2 can reach a maximum discharge capacity of 174 mA·h·g^-1 at 0.1 C rate in seventh cycle. The discharge capacity fade rate of the samples decreased with increasing Cr amount. Furthermore, o-LiMn0.95Cr0.05O2 gives a highest discharge capacity of 150 mA·h·g^-1 at a high current rate of 0.5 C, and retains 130 mA·h·g^-1 after 40 cycles.
