材料科学
普鲁士蓝
电化学
金属有机骨架
法拉第效率
熵(时间箭头)
氧化还原
组态熵
氰化物
化学工程
纳米技术
化学物理
无机化学
电极
热力学
吸附
物理化学
化学
冶金
工程类
物理
作者
Yanjiao Ma,Yuan Ma,Sören L. Dreyer,Qingsong Wang,Kai Wang,Damian Goonetilleke,Ahmad Omar,Daria Mikhailova,Horst Hahn,Torsten Brezesinski
标识
DOI:10.1002/adma.202101342
摘要
Abstract Prussian blue analogues (PBAs) are reported to be efficient sodium storage materials because of the unique advantages of their metal–organic framework structure. However, the issues of low specific capacity and poor reversibility, caused by phase transitions during charge/discharge cycling, have thus far limited the applicability of these materials. Herein, a new approach is presented to substantially improve the electrochemical properties of PBAs by introducing high entropy into the crystal structure. To achieve this, five different metal species are introduced, sharing the same nitrogen‐coordinated site, thereby increasing the configurational entropy of the system beyond 1.5R. By careful selection of the elements, high‐entropy PBA (HE‐PBA) presents a quasi‐zero‐strain reaction mechanism, resulting in increased cycling stability and rate capability. The key to such improvement lies in the high entropy and associated effects as well as the presence of several active redox centers. The gassing behavior of PBAs is also reported. Evolution of dimeric cyanogen due to oxidation of the cyanide ligands is detected, which can be attributed to the structural degradation of HE‐PBA during battery operation. By optimizing the electrochemical window, a Coulombic efficiency of nearly 100% is retained after cycling for more than 3000 cycles.
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