Revealing Nanoscale Passivation and Corrosion Mechanisms of Reactive Battery Materials in Gas Environments
Revealing Nanoscale Passivation and Corrosion Mechanisms of Reactive Battery Materials in Gas Environments
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DOI：
10.1021/acs.nanolett.7b02630
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发表时间：
2017-08-01
期刊：
影响因子：
10.8
通讯作者：
Cui, Yi
中科院分区：
文献类型：
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作者：
Li, Yuzhang;Li, Yanbin;Cui, Yi
锂（Li）金属是一种高容量阳极材料（3860 mAh g（-1）），可用于电动汽车和电网储能应用的高能电池。然而，Li金属是高度反应性的，并且当暴露于液体电解质（在电池操作期间）或周围环境（在整个电池制造过程中）时被重复消耗。由于锂金属及其表面腐蚀膜的高化学反应性，在纳米级上研究这些腐蚀反应特别困难。在这里，我们直接在环境透射电子显微镜（TEM）中生成纯Li金属，揭示了Li金属在氧气（O-2），氮气（N-2）和水蒸气（H2O）中的纳米级钝化和腐蚀过程。我们发现，虽然干燥的O-2和N-2（99.9999体积%）在锂上形成均匀的钝化层，但微量水蒸气（类似于1摩尔%）会破坏这种钝化，并在锂金属上形成多孔膜，允许气体渗透并连续与锂反应。为了利用Li在干燥条件下的自钝化行为，我们引入了Li金属的简单干燥N-2预处理以在电池组装之前形成氮化锂的保护层。Li氮化物的快速离子导电性和稳定界面导致具有无枝晶循环和低电压滞后的改进的电池性能。我们的工作揭示了锂金属钝化/腐蚀的详细过程，并展示了这种机理见解如何指导锂金属电池的工程解决方案。
Lithium (Li) metal is a high-capacity anode material (3860 mAh g(-1)) that can enable high-energy batteries for electric vehicles and grid-storage applications. However, Li metal is highly reactive and repeatedly consumed when exposed to liquid electrolyte (during battery operation) or the ambient environment (throughout battery manufacturing). Studying these corrosion reactions on the nanoscale is especially difficult due to the high chemical reactivity of both Li metal and its surface corrosion films. Here, we directly generate pure Li metal inside an environmental transmission electron microscope (TEM), revealing the nanoscale passivation and corrosion process of Li metal in oxygen (O-2), nitrogen (N-2), and water vapor (H2O). We find that while dry O-2 and N-2 (99.9999 vol %) form uniform passivation layers on Li, trace water vapor (similar to 1 mol %) disrupts this passivation and forms a porous film on Li metal that allows gas to penetrate and continuously react with Li. To exploit the self-passivating behavior of Li in dry conditions, we introduce a simple dry-N-2 pretreatment of Li metal to form a protective layer of Li nitride prior to battery assembly. The fast ionic conductivity and stable interface of Li nitride results in improved battery performance with dendrite-free cycling and low voltage hysteresis. Our work reveals the detailed process of Li metal passivation/corrosion and demonstrates how this mechanistic insight can guide engineering solutions for Li metal batteries.