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Correlating the interface resistance and surface adhesion of the Li metal-solid electrolyte interface
Journal of Power Sources ( IF 9.2 ) Pub Date : 2017-12-22 , DOI: 10.1016/j.jpowsour.2017.11.078
Michael Wang , Jeff Sakamoto

Solid electrolytes could enable stable cycling of metallic Li anodes, which can offer drastic increases to the capacity of Li-ion batteries. However, little is known about the mechanics of the Li-solid electrolyte interface. This study combines electrochemical and mechanical characterization to correlate interface kinetics with adhesive strength. Cubic garnet with the Li6·25Al0·25La3Zr2O12 (LLZO) formulation was selected as a model solid electrolyte based on its high conductivity and stability against Li metal. Symmetric Li-LLZO cells were tested using electrochemical impedance spectroscopy to determine the interfacial resistance, Rint, and the adhesive strength of the Li-LLZO interface, σadh, was measured using a unique tensile test in an inert atmosphere. It was determined that the Rint is directly correlated to the adhesive strength of Li on LLZO. At the highest Rint in this study, 330 k·cm2 the σadh was 1.1 kPa and at the lowest Rint in this study, 7 ·cm2, σadh was 8 MPa. Furthermore, by optimizing the surface chemistry the wettability of LLZO was enhanced resulting in σadh exceeding the ultimate tensile strength of Li metal. The relationship demonstrated provides a deeper understanding of the mechanical properties of the Li-electrolyte interface, which will play an important role in the design of batteries employing metallic Li anodes.



中文翻译:

关联锂金属固体电解质界面的界面电阻和表面附着力

固体电解质可以使金属锂阳极稳定循环,从而可以大大增加锂离子电池的容量。然而,关于锂-固体电解质界面的力学知之甚少。这项研究结合了电化学和机械特性,使界面动力学与粘合强度相关。选择具有Li 6·25 Al 0·25 La 3 Zr 2 O 12(LLZO)配方的立方石榴石作为模型固体电解质,因为它具有高的导电性和对Li金属的稳定性。使用电化学阻抗谱测试对称的Li-LLZO电池以确定界面电阻R int和锂LLZO接口,σ的粘合强度ADH,在惰性气氛中使用一种独特的拉伸试验来测量。已经确定,R int与Li在LLZO上的粘合强度直接相关。在此研究中,最高R int为330 k·cm 2σadh为1.1 kPa,在该研究中最低R int,为7·cm 2σadh为8 MPa。此外,通过表面化学优化LLZO的润湿性增强导致σ ADH超过锂金属的极限抗拉强度。所证明的关系提供了对锂-电解质界面的机械性能的更深入的了解,这将在采用金属锂阳极的电池设计中发挥重要作用。

更新日期:2017-12-22
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