Prussian blue analogs (PBAs) are considered as one of the most potential electrode materials in capacitive deionization (CDI) due to their unique 3D framework structure. However, their practical applications suffer from low desalination capacity and poor cyclic stability. Here, an entropy engineering strategy is proposed that incorporates high-entropy (HE) concept into PBAs to address the unfavorable multistage phase transitions during CDI desalination. By introducing five or more metals, which share N coordination site, high-entropy hexacyanoferrate (HE-HCF) is constructed, thereby increasing the configurational entropy of the system to above 1.5R and placing it into the high-entropy category. As a result, the developed HE-HCF demonstrates remarkable cycling performance, with a capacity retention rate of over 97% after undergoing 350 ultralong-life cycles of adsorption/desorption. Additionally, it exhibits a high desalination capacity of 77.24 mg g⁻¹ at 1.2 V. Structural characterization and theoretical calculation reveal that high configurational entropy not only helps to restrain phase transition and strengthen structural stability, but also optimizes Na⁺ ions diffusion path and energy barrier, accelerates reaction kinetics and thus improves performance. This research introduces a new approach for designing electrodes with high performance, low cost, and long-lasting durability for capacitive deionization applications.

中文翻译：

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熵工程约束相变使超长寿命的普鲁士蓝类似物阴极成为可能


普鲁士蓝类似物（PBA）因其独特的3D框架结构而被认为是电容去离子（CDI）中最有潜力的电极材料之一。然而，它们的实际应用存在脱盐能力低和循环稳定性差的问题。在此，提出了一种熵工程策略，将高熵（HE）概念融入到 PBA 中，以解决 CDI 海水淡化过程中不利的多级相变。通过引入五种或更多共享N配位的金属，构建了高熵六氰基铁酸盐（HE-HCF），从而将体系的构型熵提高到1.5R以上，并将其置于高熵类别。因此，所开发的HE-HCF表现出卓越的循环性能，经过350次超长寿命吸附/解吸循环后，容量保持率超过97%。此外，它在1.2 V下表现出77.24 mg g ^-1的高脱盐能力。结构表征和理论计算表明，高构型熵不仅有助于抑制相变和增强结构稳定性，而且还可以优化Na ⁺离子的扩散路径和能量势垒，加速反应动力学，从而提高性能。这项研究引入了一种新方法，用于设计用于电容去离子应用的高性能、低成本和持久耐用的电极。