Mesoscale Interrogation Reveals Mechanistic Origins of Lithium Filaments along Grain Boundaries in Inorganic Solid Electrolytes
Mesoscale Interrogation Reveals Mechanistic Origins of Lithium Filaments along Grain Boundaries in Inorganic Solid Electrolytes
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DOI：
10.1002/aenm.202102825
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发表时间：
2021-12
影响因子：
27.8
通讯作者：
B. Vishnugopi;Marm B. Dixit;Fengfeng Hao;B. Shyam;J. Cook;K. Hatzell;P. Mukherjee
中科院分区：
文献类型：
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作者：
B. Vishnugopi;Marm B. Dixit;Fengfeng Hao;B. Shyam;J. Cook;K. Hatzell;P. Mukherjee
与传统锂离子电池相比，固态电池（SSB）采用锂金属阳极，有望提供更高的能量和功率密度。电沉积过程中锂丝穿过固态电解质（SSE）对SSB的安全性和倍率性能构成了主要限制。虽然微观结构属性，尤其是 SSE 内的晶界 (GB) 被认为是优先的金属扩展路径，但其潜在机制尚未完全了解。在这里，对介观尺度的机械相互作用进行了全面的了解，包括 GB 电极结的电化学机械响应和 SSE 中的竞争离子输运动力学。根据GB传输特性，可以识别出由GB电极界面处的空腔或突起组成的高度不均匀的电沉积形态。机械稳定性分析揭示了 GB 区域的局部应变斜坡可能导致 SSE 脆性断裂。对于与晶粒相比离子导电性较低的晶界，在晶界电极连接处描绘了由电化学机械相互作用的异质性触发的裂纹形成和空隙填充机制。同时，原始和失效的 Li7La3Zr2O12 (LLZO) SSE 样品的原位 X 射线断层扫描证实了丝状锂渗透的存在以及所提出的中尺度失效机制的有效性。
Solid‐state batteries (SSBs), utilizing a lithium metal anode, promise to deliver enhanced energy and power densities compared to conventional lithium‐ion batteries. Penetration of lithium filaments through the solid‐state electrolytes (SSEs) during electrodeposition poses major constraints on the safety and rate performance of SSBs. While microstructural attributes, especially grain boundaries (GBs) within the SSEs are considered preferential metal propagation pathways, the underlying mechanisms are not fully understood yet. Here, a comprehensive insight is presented into the mechanistic interactions at the mesoscale including the electrochemical‐mechanical response of the GB‐electrode junction and competing ion transport dynamics in the SSE. Depending on the GB transport characteristics, a highly non‐uniform electrodeposition morphology consisting of either cavities or protrusions at the GB‐electrode interface is identified. Mechanical stability analysis reveals localized strain ramps in the GB regions that can lead to brittle fracture of the SSE. For ionically less conductive GBs compared to the grains, a crack formation and void filling mechanism, triggered by the heterogeneous nature of electrochemical‐mechanical interactions is delineated at the GB‐electrode junction. Concurrently, in situ X‐ray tomography of pristine and failed Li7La3Zr2O12 (LLZO) SSE samples confirm the presence of filamentous lithium penetration and validity of the proposed mesoscale failure mechanisms.