Xiao Xingcheng, Liu Zhongyi, Baggetto Loïc, Veith Gabriel M, More Karren L, Unocic Raymond R
General Motors Research and Development Center, Warren, MI, USA.
Phys Chem Chem Phys. 2014 Jun 14;16(22):10398-402. doi: 10.1039/c4cp00833b.
The structure, chemistry, and spatial distribution of Mn-bearing nanoparticles dissolved from the Li1.05Mn2O4 cathode during accelerated electrochemical cycling tests at 55 °C and deposited within the solid electrolyte interphase (SEI) are directly characterized through HRTEM imaging and XPS. Here we use air protection and vacuum transfer systems to transport cycled electrodes for imaging and analytical characterization. From HRTEM imaging, we find that a band of individual metallic Mn nanoparticles forms locally at the SEI/graphite interface while the internal and outermost layer of the SEI contains a mixture of LiF and MnF2 nanoparticles, which is confirmed with XPS. Based on our experimental findings we propose a new interpretation of how Mn is reduced from the cathode and how metallic Mn and Mn-bearing nanoparticles form within the SEI during electrochemical cycling.
在55°C加速电化学循环测试期间，从Li1.05Mn2O4阴极溶解并沉积在固体电解质界面（SEI）内的含锰纳米颗粒的结构、化学性质和空间分布通过高分辨率透射电子显微镜（HRTEM）成像和X射线光电子能谱（XPS）直接表征。在这里，我们使用空气保护和真空转移系统来运输经过循环测试的电极，以进行成像和分析表征。通过HRTEM成像，我们发现单独的金属锰纳米颗粒带在SEI/石墨界面局部形成，而SEI的内层和最外层包含LiF和MnF2纳米颗粒的混合物，这一点通过XPS得到了证实。基于我们的实验结果，我们对锰如何从阴极还原以及在电化学循环过程中金属锰和含锰纳米颗粒如何在SEI内形成提出了一种新的解释。
