Junyi Dai, Jiahao Li, Fangxin Ling, Yu Yao, Yanru Wang, Mingze Ma, Jian Feng, Jun Xia, Yinbo Zhu, Hai Yang, Xianhong Rui, Hengan Wu and Yan Yu
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引用次数: 0
Abstract
Sodium iron hexacyanoferrates (Na2FeFe(CN)6) are considered among the most promising cathode materials for sodium ion batteries due to their high theoretical energy density and low cost. However, structural Fe(CN)64− vacancies seriously impair structure stability and deteriorate electrochemical performance. So far, the mechanisms by which Fe(CN)64− vacancies cause performance degradation and ultimately result in material failure have remained unclear, leading to persistent controversies in this field. Herein, we systematically investigate the degradation mechanisms induced by Fe(CN)64− vacancies from experimental and theoretical perspectives. A defective Na2FeFe(CN)6 cathode exhibits more hysteretic low-spin iron reaction kinetics, especially during charge transfer and ion diffusion. Cryo-electron microscopy reveals that interfacial side reactions triggered by Fe(CN)64− vacancies during electrochemical cycling produce excessive Na2CO3 and NaF byproducts, which deplete electrochemically active Na+ within defective structures, causing electrochemical failure of high-spin Fe–N interactions and ultimately leading to poor structural stability. Importantly, pouch full cells (71% retention after 650 cycles) and all-solid-state batteries (82% retention after 500 cycles) fabricated from industrial-scale low-defect Na2FeFe(CN)6 cathodes exhibit excellent cycling stability. This work offers valuable mechanistic insights into vacancy-induced degradation of Na2FeFe(CN)6 cathodes and contributes to the advancement of practical sodium storage cathode materials.
期刊介绍:
Energy & Environmental Science, a peer-reviewed scientific journal, publishes original research and review articles covering interdisciplinary topics in the (bio)chemical and (bio)physical sciences, as well as chemical engineering disciplines. Published monthly by the Royal Society of Chemistry (RSC), a not-for-profit publisher, Energy & Environmental Science is recognized as a leading journal. It boasts an impressive impact factor of 8.500 as of 2009, ranking 8th among 140 journals in the category "Chemistry, Multidisciplinary," second among 71 journals in "Energy & Fuels," second among 128 journals in "Engineering, Chemical," and first among 181 scientific journals in "Environmental Sciences."
Energy & Environmental Science publishes various types of articles, including Research Papers (original scientific work), Review Articles, Perspectives, and Minireviews (feature review-type articles of broad interest), Communications (original scientific work of an urgent nature), Opinions (personal, often speculative viewpoints or hypotheses on current topics), and Analysis Articles (in-depth examination of energy-related issues).