Tunable Platform Capacity of Metal–Organic Frameworks via High-Entropy Strategy for Ultra-Fast Sodium Storage
Shusheng Tao, Ziwei Cao, Xuhuan Xiao, Zirui Song, Dengyi Xiong, Ye Tian, Wentao Deng, Youcai Liu, Hongshuai Hou, Guoqiang Zou, Xiaobo Ji
Abstract
Abstract Precise regulation of the platform capacity/voltage of electrode materials contributes to the efficient operation of sodium-ion fast-charging devices. However, the design of such electrode materials is still in a blank stage. Herein, based on tunable metal–organic frameworks, we have designed a novel material system—two-dimensional high-entropy metal–organic frameworks (HE-MOFs), which exhibits unique properties in sodium storage and is of vital importance for realizing fast-charging batteries. Furthermore, we have found that the high-entropy effect can regulate the electronic structure, the sodium-ion migration environment, and the sodium-ion storage active sites, thereby meeting the requirements of electrode materials for sodium-ion fast-charging devices. Impressively, the HE-MOFs material still maintains a reversible specific capacity of 89 mAh g −1 at a current density of 20 A g −1 . It presents an ideal sodium storage voltage plateau of approximately 0.5 V, and its platform capacity is increased to 122.7 mAh g −1 , far superior to that of Mn-MOFs (with no platform capacity). This helps to reduce safety hazards during the fast-charging process and demonstrates its great application value in the fields of fast-charging sodium-ion batteries and capacitors. Our research findings have broken the barriers to the application of non-conductive MOFs as energy storage materials, enhanced the understanding of the regulation of platform capacity and voltage, and paved the way for the realization of high-security sodium-ion fast-charging devices.