Transient Polarization and Dendrite Initiation Dynamics in Ceramic Electrolytes
Transient Polarization and Dendrite Initiation Dynamics in Ceramic Electrolytes
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DOI：
10.1021/acsenergylett.3c00499
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发表时间：
2021-10
影响因子：
22
通讯作者：
R. Gopal;Long-mei Wu;Youngju Lee;Jinzhao Guo;P. Bai
中科院分区：
文献类型：
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作者：
R. Gopal;Long-mei Wu;Youngju Lee;Jinzhao Guo;P. Bai
固态电解质通过启用锂金属阳极可以显著增加当前锂离子电池的能量密度。然而，类似于它们的液体对应物，这些硬和硬电解质仍然可以被软Li金属渗透，超过临界电流密度（CCD）。确定CCD的流行方法采用逐步恒电流循环，其遭受不一致的活性界面面积，由于重复剥离和电镀后的空隙形成，在报告的数据中留下大的差异，妨碍精确的理解。在这里，我们联合收割机的单向极化技术与电化学阻抗谱揭示，第一次，在陶瓷电解质中存在显着的极化动力学。与由于金属渗透而产生的发散瞬态电流相反，我们观察到的电流峰值表明了一种扩散限制机制，该机制遵循经典的Randles-Sevcik方程，用于分析液体电解质中的扩散限制过程。我们的研究结果允许一个严格的自洽分析，揭示了CCD是一个扩散限制的电流密度，而系统特定的陶瓷电解质的极限电流密度仍然低于CCD，这表明在陶瓷电解质中的枝晶穿透之前的离子传输机制是统一的液体电解质。
Solid-state electrolytes, by enabling lithium metal anodes, may significantly increase the energy density of current lithium-ion batteries. However, similar to their liquid counterparts, these hard and stiff electrolytes can still be penetrated by soft Li metal, above a critical current density (CCD). The prevailing method to determine the CCD employs step-wise galvanostatic cycling, which suffers from inconsistent active interfacial areas due to void formations after repeated stripping and plating, leaving large variance in the reported data that preclude precision understandings. Here, we combine a one-way polarization technique with electrochemical impedance spectroscopy to uncover, for the first time, the existence of significant polarization dynamics in ceramic electrolytes. In contrast to the diverging transient current due to metal penetration, the current peaks we observed suggest a diffusion-limited mechanism that follows the classic Randles-Sevcik equation for analyzing the diffusion-limited processes in liquid electrolytes. Our results allow a rigorous self-consistent analysis to reveal that the CCD is a diffusion-limited current density, while the system-specific limiting current density for ceramic electrolytes is still lower than CCD, which suggests that the ion transport mechanism preceding the dendrite penetration in ceramic electrolytes is unifiable with that in liquid electrolytes.