Lithium metal is a favorable anode material in all-solid Li-polymer batteries because of its high energy density. However, dendrite formation on lithium metal causes safety concerns. Here we obtain images of the Li-metal anode surface during cycling using in situ scanning electron microscopy. Constructing videos from the images enables us to monitor the failure mechanism of the battery. Our results show the formation of dendrites on the edge of the anode and isles of decomposed lithium bis(trifluoromethanesulfonyl)imide on the grain boundaries. Cycling at high rates results in the opening of the grain boundaries and depletion of lithium in the vicinity of the isles. We also observe changes in the surface morphology of the polymer close to the anode edge. Extrusion of lithium from these regions could be evidence of polymer reduction due to a local increase in temperature and thermal runaway assisting in dendrite formation.

锂金属由于其高能量密度而在全固态锂聚合物电池中是一种有利的负极材料。但是，在锂金属上形成枝晶会引起安全隐患。在这里，我们使用原位扫描电子显微镜获得了循环过程中锂金属阳极表面的图像。根据图像构造视频，使我们能够监视电池的故障机理。我们的结果表明，在阳极边缘上形成了树枝状晶体，在晶界上形成了分解的双（三氟甲磺酰基）酰亚胺锂。高速循环导致晶界的开放和岛附近锂的耗尽。我们还观察到靠近阳极边缘的聚合物表面形态的变化。