LiMn_2O_4/LiPF_6-(EC+DEC)溶液界面电化学研究

Electrochemical Investigation on the Interface Performances of LiMn_2O_4/LiPF_6-(EC+DEC) Solution

用交流阻抗谱结合循环伏安曲线研究了LiMn2O4粉末微电极在充放电循环及贮存情况下,LiMn2O4/LiPF6-(EC+DEC)溶液界面性质变化。结果表明,LiMn2O4经充放电循环,其表面膜电阻及膜电容在循环初期增加显著,但后期变化不大,界面电荷传递电阻显著增加而界面电容变化不明显;经贮存,其膜电阻在贮存初期减小,后期反而稍有增加,界面电荷传递电阻呈增加趋势,尤其在初期增加幅度较大,膜电容及界面电容变化不明显。对引起这些界面参数变化的可能原因进行了解释。

The Changes in interface performances of LiMn2O4/LiPF6-(EC+DEC) solution with before and after charge-discharge cycling and storage were investigated by impedance technique combined with cyclic voltammetry. The resistance and the capacitance of the surface film increase significantly during the first several cycles, but nearly remain unchanged later. The charge-transfer resistance increases, but the interface capacitance nearly remains unchanged. The surface film resistance decreases at the early stage during storage but then increases a little with time. The charge-transfer resistance increases significantly after storage, especially at the early stage during storage. The surface film capacitance and interface capacitance nearly remain unchanged during storage. Possible mechanisms for the changes in these interface performances were explained.