Department of Industrial Chemistry, University of Bologna, Viale Risorgimento 4, 40136, Bologna, Italy.
Elettra - Sincrotrone Trieste, s.s. 14, km 163.5, Basovizza, 34149, Trieste, Italy.
ChemSusChem. 2023 Jun 22;16(12):e202300201. doi: 10.1002/cssc.202300201. Epub 2023 Apr 19.
Manganese hexacyanoferrates (MnHCF) are promising positive electrode materials for non-aqueous batteries, including Na-ion batteries, due to their large specific capacity (>130 mAh g ), high discharge potential and sustainability. Typically, the electrochemical reaction of MnHCF associates with phase and structural changes, due to the Jahn-Teller (JT) distortion of Mn sites upon the charge process. To understand the effect of the MnHCF structure on its electrochemical performance, two MnHCF materials with different vacancies content are investigated herein. The electrochemical results show that the sample with lower vacancy content (4 %) exhibits relatively higher capacity retention of 99.1 % and 92.6 % at 2 and 10 cycles, respectively, with respect to 97.4 % and 79.3 % in sample with higher vacancy content (11 %). Ex-situ X-ray absorption spectroscopy (XAS) and ex situ X-ray diffraction (XRD) characterization results show that a weaker cooperative JT-distortion effect and relatively smaller crystal structure modification occurred for the material with lower vacancies, which explains the better electrochemical performance in cycled electrodes.
锰铁氰化酸盐（MnHCF）是一种很有前途的非水电池正极材料，包括钠离子电池，因为它们具有大的比容量（>130mAhg）、高放电电位和可持续性。通常，MnHCF 的电化学反应与相和结构变化有关，这是由于在充电过程中 Mn 位的 Jahn-Teller（JT）变形。为了了解 MnHCF 结构对其电化学性能的影响，本文研究了两种具有不同空位含量的 MnHCF 材料。电化学结果表明，空位含量较低（4%）的样品在 2 次和 10 次循环时的容量保持率相对较高，分别为 99.1%和 92.6%，而空位含量较高（11%）的样品分别为 97.4%和 79.3%。原位 X 射线吸收光谱（XAS）和原位 X 射线衍射（XRD）表征结果表明，空位含量较低的材料中 JT 变形的协同效应较弱，晶体结构的修饰也较小，这解释了循环电极中更好的电化学性能。
