论文标题
分离的电解质微通道中的浓度极化和金属树突启动
Concentration Polarization and Metal Dendrite Initiation in Isolated Electrolyte Microchannels
论文作者
论文摘要
锂金属通过液体润湿的多孔分离器和固体电解质的渗透是下一代可充电金属电池的主要安全问题。经常发现穿透性仅通过几个孤立的通道发生，如分离器或电解质两侧的“黑点”所揭示的，这表现出高度局部的离子通量或电流密度。由于这些穿透通道中隐藏和不清楚的动态，对穿透时间的预测是不可行的。在这里，使用玻璃毛细管细胞，我们首次研究了通道几何形状对浓度极化和树突启动过程的意外敏感的影响。在前进电极表面完全消耗盐浓度的特征时间，即沙子的时间，表现出非线性依赖于沿轴向方向的通道壁的曲率。虽然可以使用阳性偏差的沙子时间缩放指数通过电解质来推断融合的穿透区域，但呈负偏差的缩放指数表明，可以避免扩散限制在扩展通道中，因此不会启动快速扩增的尖端生长的树突。可充电金属电池的安全设计将受益于考虑真正的局部电流密度和传导结构。
Lithium metal penetrations through the liquid-electrolyte-wetted porous separator and solid electrolytes are a major safety concern of next-generation rechargeable metal batteries. The 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 infeasible due to the hidden and unclear dynamics in these penetration channels. Here, using the 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 on 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 limitation 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.
