The Ti-Supported MnO_2 electrode was modified by introducing SnO_2+RuO_2+MnO_2 as an intermediate layer into the Ti/MnO_2 interface. The anodic polarization curves were measured at various temperatures ranging from 30...The Ti-Supported MnO_2 electrode was modified by introducing SnO_2+RuO_2+MnO_2 as an intermediate layer into the Ti/MnO_2 interface. The anodic polarization curves were measured at various temperatures ranging from 30 to 80℃ and the activation energy for the oxygen evolution reaction was evaluated. The experimental activation energy increased linearly with increasing the overpotential. The activation energy at the equilibrium potential was linearly correlated with the difference between the crystal field stabilization energies of Mn^(4+) at initial state and Mn^(4+) at transition state. The electrocatalysis characteristics of the anode were discussed by means of the mechanism of the substitution reaction of the ligand(S_N1 and S_N2) and molecular orbital theory. The results show that the anode has better electrocatalystic characteristics.展开更多
采用钛酸四丁酯[Ti(OC_4H_9)_4]水解和900℃高温烧结工艺制得不同Ti^(4+)含量掺杂下的Li[Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]_(1-x)Ti_xO_2正极材料。采用XRD、SEM等表征方法对Ti^(4+)掺杂前后的Li[Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0....采用钛酸四丁酯[Ti(OC_4H_9)_4]水解和900℃高温烧结工艺制得不同Ti^(4+)含量掺杂下的Li[Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]_(1-x)Ti_xO_2正极材料。采用XRD、SEM等表征方法对Ti^(4+)掺杂前后的Li[Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]O_2颗粒的微观结构、表面形貌进行分析研究,发现掺杂前后材料的结构并未明显变化。电化学测试结果表明,虽然Ti^(4+)表现为非电化学活性,使得掺杂有Ti^(4+)的正极材料其首次充放电比容量有所降低,但是在高倍率性能及循环性能测试中,Ti^(4+)掺杂改性效果表现明显。其中当Ti^(4+)掺杂量为x=0.02时,其倍率性能及循环性能最佳。在5C高倍率下放电,Li[Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]_(0.98)Ti_(0.02)O_2样品的放电比容量要比未掺杂样品高出约20 m A·h/g。而且经过100次循环后,Li[Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]_(0.98)Ti_(0.02)O_2样品的放电比容量仍有187.9 m A·h/g,容量保持率高达96.8%。而未掺杂样品的100次循环后容量保持率仅有91.2%。展开更多
基金Supported by the National Natural Science Foundation of China.
文摘The Ti-Supported MnO_2 electrode was modified by introducing SnO_2+RuO_2+MnO_2 as an intermediate layer into the Ti/MnO_2 interface. The anodic polarization curves were measured at various temperatures ranging from 30 to 80℃ and the activation energy for the oxygen evolution reaction was evaluated. The experimental activation energy increased linearly with increasing the overpotential. The activation energy at the equilibrium potential was linearly correlated with the difference between the crystal field stabilization energies of Mn^(4+) at initial state and Mn^(4+) at transition state. The electrocatalysis characteristics of the anode were discussed by means of the mechanism of the substitution reaction of the ligand(S_N1 and S_N2) and molecular orbital theory. The results show that the anode has better electrocatalystic characteristics.
文摘采用钛酸四丁酯[Ti(OC_4H_9)_4]水解和900℃高温烧结工艺制得不同Ti^(4+)含量掺杂下的Li[Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]_(1-x)Ti_xO_2正极材料。采用XRD、SEM等表征方法对Ti^(4+)掺杂前后的Li[Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]O_2颗粒的微观结构、表面形貌进行分析研究,发现掺杂前后材料的结构并未明显变化。电化学测试结果表明,虽然Ti^(4+)表现为非电化学活性,使得掺杂有Ti^(4+)的正极材料其首次充放电比容量有所降低,但是在高倍率性能及循环性能测试中,Ti^(4+)掺杂改性效果表现明显。其中当Ti^(4+)掺杂量为x=0.02时,其倍率性能及循环性能最佳。在5C高倍率下放电,Li[Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]_(0.98)Ti_(0.02)O_2样品的放电比容量要比未掺杂样品高出约20 m A·h/g。而且经过100次循环后,Li[Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]_(0.98)Ti_(0.02)O_2样品的放电比容量仍有187.9 m A·h/g,容量保持率高达96.8%。而未掺杂样品的100次循环后容量保持率仅有91.2%。
