通过简易的无焰燃烧法合成了LiMn2O4、LiNi0.08Mn1.92O4和LiNi0.08Cu0.05Mn1.87O43种正极材料。利用XRD、SEM、恒电流充放电测试等手段对合成材料的结构、形貌和电化学性能进行了表征。结果表明,所制备的3种正极材料均为立方尖晶石结构;...通过简易的无焰燃烧法合成了LiMn2O4、LiNi0.08Mn1.92O4和LiNi0.08Cu0.05Mn1.87O43种正极材料。利用XRD、SEM、恒电流充放电测试等手段对合成材料的结构、形貌和电化学性能进行了表征。结果表明,所制备的3种正极材料均为立方尖晶石结构;Ni-Cu共掺杂提高了LiNi0.08Cu0.05Mn1.87O4材料的晶体结构稳定性,表现出比LiNi0.08Mn1.92O4和LiMn2O4材料较好的倍率性能和循环寿命。在室温和1 C倍率下,LiNi0.08Cu0.05Mn1.87O4样品的首次比容量为104.7 m A·h/g,循环200次后的容量保持率为81.38%;在较高的倍率5 C循环1000次后,容量保持率为68.23%;即使在高温55℃和1 C倍率下,仍可获得较高的首次放电比容量,为110.8 m A·h/g,200次循环后的容量保持率为56.23%。CV和EIS测试结果表明,LiNi0.08Cu0.05Mn1.87O4具有较好的循环可逆性和较小的电荷转移阻抗。展开更多
Cobalt was used to modify the surface of spinel LiMn2O4 by a solution technique to produce Co3+-modified surface material (COMSM). Cobalt was only doped into the surface of LiMn2O4 spinel. XPS(X-ray photoelectron spec...Cobalt was used to modify the surface of spinel LiMn2O4 by a solution technique to produce Co3+-modified surface material (COMSM). Cobalt was only doped into the surface of LiMn2O4 spinel. XPS(X-ray photoelectron spectroscopy) analysis confirms the valence state of Co3+. COMSM has stable spinel structure and can prevent active materials from the corrosion of electrolyte. The ICP(inductively coupled plasma) determination of the spinel dissolution in electrolyte showed the content of Mn dissolved from COMSM was smaller than that from the pure spinel. AC impedance patterns show that the charge-transfer resistance (Rct) for COMSM is smaller than that for pure spinel. The particles of COMSM are bigger in size than those of pure spinel according to the micrographs of SEM(scanning electron microscopy). The determinations of the electrochemical characterization show that COMSM has both good cycling performance and high initial capacity of 124.1 mA/h at an average capacity loss of 0.19 mAh/g per cycle.展开更多
文摘通过简易的无焰燃烧法合成了LiMn2O4、LiNi0.08Mn1.92O4和LiNi0.08Cu0.05Mn1.87O43种正极材料。利用XRD、SEM、恒电流充放电测试等手段对合成材料的结构、形貌和电化学性能进行了表征。结果表明,所制备的3种正极材料均为立方尖晶石结构;Ni-Cu共掺杂提高了LiNi0.08Cu0.05Mn1.87O4材料的晶体结构稳定性,表现出比LiNi0.08Mn1.92O4和LiMn2O4材料较好的倍率性能和循环寿命。在室温和1 C倍率下,LiNi0.08Cu0.05Mn1.87O4样品的首次比容量为104.7 m A·h/g,循环200次后的容量保持率为81.38%;在较高的倍率5 C循环1000次后,容量保持率为68.23%;即使在高温55℃和1 C倍率下,仍可获得较高的首次放电比容量,为110.8 m A·h/g,200次循环后的容量保持率为56.23%。CV和EIS测试结果表明,LiNi0.08Cu0.05Mn1.87O4具有较好的循环可逆性和较小的电荷转移阻抗。
基金supported by the Basic Research Fund of Tsinghua University under grant No.JC1999054‘985’Project of School of Materials Science and Engineering of Tsinghua Universitythe Scientific Fund of the Education Committee of Fujian Province.
文摘Cobalt was used to modify the surface of spinel LiMn2O4 by a solution technique to produce Co3+-modified surface material (COMSM). Cobalt was only doped into the surface of LiMn2O4 spinel. XPS(X-ray photoelectron spectroscopy) analysis confirms the valence state of Co3+. COMSM has stable spinel structure and can prevent active materials from the corrosion of electrolyte. The ICP(inductively coupled plasma) determination of the spinel dissolution in electrolyte showed the content of Mn dissolved from COMSM was smaller than that from the pure spinel. AC impedance patterns show that the charge-transfer resistance (Rct) for COMSM is smaller than that for pure spinel. The particles of COMSM are bigger in size than those of pure spinel according to the micrographs of SEM(scanning electron microscopy). The determinations of the electrochemical characterization show that COMSM has both good cycling performance and high initial capacity of 124.1 mA/h at an average capacity loss of 0.19 mAh/g per cycle.
