Resolving Deactivation of Low-Spin Fe Sites by Redistributing Electron Density toward High-Energy Sodium Storage.

Jiang, Mingwei; Hou, Zhidong; Ma, Honghao; Wang, Jinjin; Hua, Wei; Ren, Lingbo; Zhang, Yu; Wei, Chunguang et al. · Nano Lett · 2023

basic_science · Level V

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Abstract

Prussian blue (PB) has been an emerging class of cathode material for sodium-ion batteries due to its low cost and high theoretical capacity. However, their working voltage and capacity are substantially restricted due to the deactivation of low-spin Fe sites. Herein, we demonstrate a universal strategy to activate the low-spin Fe sites of PB by hybridizing them with the π-π conjugated electronic conductors. The redistribution of electron density between π-π conjugated conductors and PB effectively promotes the participation of low-spin Fe sites in sodium storage. Consequently, the low-spin Fe-induced plateau is greatly aroused, resulting in a high specific capacity of 148.4 mAh g<sup>-1</sup> and remarkable energy density of 444.2 Wh kg<sup>-1</sup>. In addition, the excellent structural stability enables superior cycling stability over 2500 cycles and outstanding rate performance. The work will provide fundamental insight into activating the low-spin Fe sites of PB for advanced battery technologies.