Concentration polarization and metal dendrite initiation in isolated electrolyte microchannels
Concentration polarization and metal dendrite initiation in isolated electrolyte microchannels
复制标题
DOI：
10.1039/d0ee01874k
复制
发表时间：
2020-10-01
影响因子：
32.5
通讯作者：
Bai, Peng
中科院分区：
文献类型：
--
作者：
Lee, Youngju;Ma, Bingyuan;Bai, Peng
锂金属渗透通过液体电解质润湿的多孔隔膜和固体电解质是下一代可再充电金属电池的主要安全问题。经常发现渗透仅通过少数隔离通道发生，如隔板或电解质两侧的“黑点”所揭示的，其表现出高度局部化的离子通量或电流密度。由于这些渗透通道中隐藏的和不清楚的动态，渗透时间的预测一直很困难。在这里，使用玻璃毛细管细胞，我们调查的第一次意想不到的敏感影响的通道几何形状的浓度极化和枝晶的起始过程。在前进电极的表面处盐浓度完全耗尽的特征时间，即沙的时间，表现出对通道壁沿着轴向的曲率的非线性依赖性。虽然正偏离的沙的时间标度指数可用于推断通过电解质的会聚渗透面积，但负偏离的标度指数表明，扩散限制可在扩展通道中避免，使得快速推进的尖端生长的枝晶将不会被引发。考虑真实的局部电流密度和导电结构，将有利于可充电金属电池的安全设计。
Lithium metal penetrations through the liquid-electrolyte-wetted porous separator and solid electrolytes are a major safety concern of next-generation rechargeable metal batteries. Penetrations were frequently discovered to occur through only a few isolated channels, as revealed by "black spots" on both sides of the separator or electrolyte, which manifest a highly localized ionic flux or current density. Predictions of the penetration time have been difficult due to the hidden and unclear dynamics in these penetration channels. Here, using glass capillary cells, we investigate for the first time the unexpectedly sensitive influence of channel geometry on the concentration polarization and dendrite initiation processes. The characteristic time for the complete depletion of salt concentration at the surface of the advancing electrode,i.e.Sand's time, exhibits a nonlinear dependence on the curvature of the channel walls along the axial direction. While a positively deviated Sand's time scaling exponent can be used to infer a converging penetration area through the electrolyte, a negatively deviated scaling exponent suggests that diffusion limitations can be avoided in expanding channels, such that the fast-advancing tip-growing dendrites will not be initiated. The safety design of rechargeable metal batteries will benefit from considering the true local current densities and the conduction structures.