论文标题
跟踪LIMN2O4通过原位TEM对LIMN2O4的扩散岩石反应
Tracking the diffusion-controlled lithiation reaction of LiMn2O4 by in-situ TEM
论文作者
论文摘要
尖晶石锂氧化锂（Lixmn2O4）用作电池阴极中的活性材料。它是一种相对便宜且环保的材料，但在使用过程中遭受了容量的淡出。容量损失通常归因于四方相（x> 1）的形成，这是由于在商业电极中使用的微米大小颗粒表面的过电位。在这项研究中，我们通过利用衍射和高分辨率以及光谱法进行了透射电子显微镜（TEM）中的电化学锂化（放电），研究四方相形成的机制。我们观察到立方尖晶石（x = 1）和四方相（x = 2）之间的尖锐界面，该界面在锂扩散控制下移动。四方相形成是一种复杂的纳米含量微观结构，大概是为了减轻静脉内膨胀引起的应力。我们提出，孪生的微观结构稳定了四方相，从而增加了深层排放后的容量损失。
Spinel lithium manganese oxide (LixMn2O4) is used as an active material in battery cathodes. It is a relatively inexpensive and environmentally friendly material, but suffers from capacity fade during use. The capacity losses are generally attributed to the formation of the tetragonal phase (x > 1) due to overpotentials at the surfaces of the micron-sized particles that are used in commercial electrodes. In this study, we investigate the mechanisms of tetragonal phase formation by performing electrochemical lithiation (discharging) in-situ in the transmission electron microscope (TEM) utilizing diffraction and high resolution as well as spectroscopy. We observe a sharp interface between the cubic spinel (x = 1) and the tetragonal phase (x = 2), that moves under lithium diffusion-control. The tetragonal phase forms as a complex nanotwinned microstructure, presumably to relieve the stresses due to expansion during lithiation. We propose that the twinned microstructure stabilizes the tetragonal phase, adding to capacity loss upon deep discharge.
