Reliable Microscopy and Microanalysis Strategies for Real-World Batteries
Reliable Microscopy and Microanalysis Strategies for Real-World Batteries
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适用于实际电池的可靠显微镜和微量分析策略
DOI：
10.1093/micmic/ozad067.049
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发表时间：
2023
影响因子：
2.8
通讯作者：
He, Kai
中科院分区：
文献类型：
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作者：
He, Kai
可充电电池包括锂离子电池（Li-ion batteries，LIB）和超锂电池，是现代社会不可或缺的储能设备，可提高可再生能源的利用率，实现碳中和使命。透射电子显微镜（TEM）是一种不可或缺的分析方法，可以在原子分辨率下表征材料结构和成分，这对于电池研究特别强大，可以研究电池电极，电解质和其他组件中使用的材料的晶格，微观结构，局部缺陷和化学成分[1]。原位TEM的最新进展使得能够实时观察电池循环过程中的各种动力学现象和化学过程以及相关的相变，表明其本身是该领域中快速增长的领域[2]。然而，为了获得准确和可靠的结果，需要解决几个紧迫的挑战。两个最重要的问题是高能电子束的辐射损伤和锂（或其他碱金属）化合物与空气中的水分和氧气之间的副反应。此外，在相同工作条件下进行操作测试的能力对于新电池的设计和开发至关重要。因此，迫切需要开发可靠的电子显微镜和微分析策略来表征，分析和诊断真实世界的电池材料。我们已经开发并展示了有效的方法和仪器来解决现实电池中的科学问题。图1显示了一个示意图，概述了关键问题和克服或减轻这些问题的相关战略。具体地，为了最小化电子束辐射的影响，具有低kV和低剂量设置的TEM技术通常用于保持原始材料结构免受撞击损伤，而低温TEM在低温下冷冻含锂样品可以有效地保留固有结构，以允许敏感材料和界面（如锂金属和固体电解质界面（SEI））的原子级成像[3].另一方面，电池内部的锂和碱金属及其化合物对周围环境也非常敏感，在样品制备和转移过程中容易通过与氧气和水分的副反应产生不需要的副产物。在这方面，对于电池表征和诊断的理想工作流程，需要无空气传输系统的必要需求。一种特殊的无空气TEM保持器已被证明其在FIB制备过程中以及随后在显微镜真空室和惰性气体填充手套箱之间转移时确保良好保护的有效性[4]。此外，基于MEMS的平台能够实现具有操作电化学测试功能的原位TEM，可以提供将电池结构和组成与功能和性能联系起来的直接关系[5]。总的来说，合理选择合适的实验设置和工作流程将保证有效和精确的电子显微镜和微观分析与现实世界的应用相关的敏感材料[6]。
Rechargeable batteries, including Li-ion batteries (LIBs) and beyond-Li batteries, are essential energy storage devices to electrify the modern society, improving the utilization of renewable energy sources and achieving the carbon neutralization mission. Transmission electron microscopy (TEM) is an indispensable analytical methodology to characterize materials structure and composition at atomic resolution, which is particularly powerful for battery research to investigate the crystal lattices, microstructures, local defects, and chemical compositions of materials used in battery electrodes, electrolytes, and other components [1]. Recent advancement of in situ TEM has enabled the real-time observation of various dynamical phenomena and chemical processes during battery cycling and the associated phase transformations, manifesting itself a rapidly growing area in this field [2]. However, there are several pressing challenges that need to be addressed in order to obtain accurate and reliable results. Two of the most significant issues are the radiation damage by the high-energy electron beam and the side reactions between lithium (or other alkali metals) compounds and moisture and oxygen in the air. In addition, the capability to perform operando tests under the same working conditions is vital to the new battery design and development. Therefore, it is desired and urgently needed to develop reliable electron microscopy and microanalysis strategies for characterization, analysis, and diagnosis of real-world battery materials.We have developed and demonstrated effective methodology and instrumentation to tackle with the scientific questions in realistic batteries. Figure 1 shows a schematic illustration summarizing the critical issues and the relevant strategies to overcome or mitigate those problems. Specifically, to minimize the impact of electron beam radiation, TEM techniques with low-kV and lowdose settings are typically useful to maintain the original material structures from knock-on damage, while cryo-TEM to freeze the Li-containing sample at low temperatures can effectively preserve the intrinsic structures to allow for atomic-scale imaging of the sensitive materials and interfaces such as Li metal and solid-electrolyte interphase (SEI)[3]. From another aspect, Li and alkali metals and their compounds inside batteries are also extremely sensitive to ambient environments, easily causing unwanted byproducts through side reactions with oxygen and moisture during sample preparation and transfer. In this regard, a necessary need of air-free transfer system is required for an ideal workflow of battery characterization and diagnosis. A special air-free TEM holder has been demonstrated its effectiveness in assuring excellent protection during FIB preparation and the subsequent transfer between microscope vacuum chambers and inert gas-filled glovebox [4]. Furthermore, MEMS-based platform that enables in situ TEM with operando electrochemical testing functions can provide direct relationship linking the battery structures and compositions with the functionality and performance [5]. Overall, rationally choosing appropriate experimental setups and workflows will promise effective and precise electron microscopy and microanalysis for sensitive materials relevant to real-world applications [6].