Na-ion and K-ion batteries are promising alternatives for large-scale energy storage due to their abundance and low cost. Intercalation of these large ions could cause irreversible structural deformation and partial to complete amorphization in the crystalline electrodes. A lack of understanding of the dynamic changes in the amorphous nanostructure during battery operation is the bottleneck for further developments. Here, we report the utilization of in-operando digital image correlation and XRD techniques to probe dynamic changes in the amorphous phase of iron phosphate during potassium ion intercalation. In-operando XRD demonstrates amorphization in the electrode’s nanostructure during the first charge and discharge cycle. Additionally, ex situ HR-TEM further confirms the amorphization after potassium-ion intercalation. An in situ strain analysis detects reversible deformations associated with redox reactions in the amorphous phases. Our approach offers new insights into the mechanism of ion intercalation in the amorphous nanostructure which are highly potent for the development of next-generation batteries.

中文翻译：

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原位探测结晶磷酸铁阴极材料中钾离子插层诱导的非晶化

钠离子和钾离子电池因其丰富且成本低而成为大规模储能的有前途的替代品。这些大离子的嵌入可能导致晶体电极中不可逆的结构变形和部分完全非晶化。对电池运行过程中非晶纳米结构的动态变化缺乏了解是进一步发展的瓶颈。这里，我们报告IN-的利用率operando数字图像相关和XRD技术中的钾离子嵌入探测在磷酸铁的无定形相中的动态变化。IN- operando XRD第一充电和放电循环期间演示在电极的纳米结构的非晶化。此外，异地HR-TEM 进一步证实了钾离子嵌入后的非晶化。一个原位应变分析检测到与在非晶相的氧化还原反应相关的可逆变形。我们的方法为离子嵌入非晶纳米结构中的机制提供了新的见解，这对于开发下一代电池非常有效。