Uncovering the Relationship between Diameter and Height of Electrodeposited Lithium Protrusions in a Rigid Electrolyte,ACS Applied Energy Materials

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Uncovering the Relationship between Diameter and Height of Electrodeposited Lithium Protrusions in a Rigid Electrolyte
ACS Applied Energy Materials ( IF 5.4 ) Pub Date : 2020-09-14 , DOI: 10.1021/acsaem.0c01175
Alec S. Ho _{1,

2} , Pallab Barai ₃ , Jacqueline A. Maslyn _{1,

2} , Louise Frenck ₁ , Whitney S. Loo ₁ , Dilworth Y. Parkinson ₄ , Venkat Srinivasan ₃ , Nitash P. Balsara _{1,

2,

5}

Affiliation

A promising approach for enabling rechargeable batteries with significantly higher energy densities than current lithium-ion batteries is by deploying lithium-metal anodes. However, the growth of lithium protrusions during charging presents significant challenges. Since these protrusions are often branched and filamentous in conventional liquid electrolytes, this problem is referred to in the literature as the “dendrite problem”. While solid electrolytes have the potential to solve this problem, protrusions grow in all electrolytes when the current density exceeds a critical value. Fundamentally understanding the formation is necessary to develop a rational approach for increasing the critical current density, but it is challenging due to the complex interplay between electrochemical and material properties. The diameters and heights of protrusions on lithium-metal anodes stabilized by a rigid block copolymer electrolyte were measured in situ by synchrotron hard X-ray microtomography. The diameter of the shorting protrusions increased linearly with increasing electrolyte thickness. Further, a universal linear relationship between protrusion height and diameter of both shorting and non-shorting protrusions was observed. A model based on the concentrated solution theory was used to establish the electrochemical and mechanical sources for our observations. The computational analysis indicates that elastic and plastic deformation of both the lithium metal and the polymer are important to describe protrusion growth. Both stress-induced current density effects due to the deformation of the electrolyte near the protrusion and plastic deformation of lithium metal combine to give the counterintuitive result: the fastest-growing protrusions have the largest diameter.

中文翻译：

揭示刚性电解质中电沉积锂凸出物的直径与高度之间的关系

通过部署锂金属阳极，一种使能量密度明显高于当前锂离子电池的可再充电电池的有前途的方法是。然而，在充电期间锂突起的生长提出了重大挑战。由于这些突起在常规的液体电解质中通常是分支的和丝状的，因此该问题在文献中被称为“树枝状问题”。尽管固体电解质有解决这个问题的潜力，但是当电流密度超过临界值时，所有电解质中都会出现突起。从根本上理解形成是开发合理的方法来增加临界电流密度所必需的，但是由于电化学和材料特性之间复杂的相互作用，因此具有挑战性。通过同步加速器硬X射线显微照相术原位测量通过刚性嵌段共聚物电解质稳定的锂金属阳极上的突起的直径和高度。短路突起的直径随着电解质厚度的增加而线性增加。此外，观察到突起高度与短路和非短路突起的直径之间的通用线性关系。基于浓溶液理论的模型用于建立我们的观测的电化学和机械来源。计算分析表明，锂金属和聚合物的弹性和塑性变形对于描述突起的生长很重要。

更新日期：2020-10-26

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