材料科学
阴极
钠离子电池
氧化还原
化学工程
锂(药物)
密度泛函理论
电极
分析化学(期刊)
电化学
物理化学
冶金
法拉第效率
医学
工程类
内分泌学
计算化学
化学
色谱法
作者
Natalia Voronina,Hee Jae Kim,Aishuak Konarov,Najma Yaqoob,Kug‐Seung Lee,Payam Kaghazchi,Olivier Guillon,Seung‐Taek Myung
标识
DOI:10.1002/aenm.202003399
摘要
Abstract In this work, the rational design of O′3‐type Na[Ni 2/3− x Co x Sb 1/3 ]O 2 , a solid solution of Na[Ni 2/3 Sb 1/3 ]O 2 –Na[Co 2/3 Sb 1/3 ]O 2 , is introduced. Because of the difficulty of the Co 3+/2+ redox reaction, the electronic structures of Na[Ni 2/3− x Co x Sb 1/3 ]O 2 compounds are engineered to build electroconducting networks in the oxide matrix through electrochemical oxidation of Co 2+ to Co 3+ , after which the formed Co 3+ does not participate in the electrochemical reaction but improves the electrical conductivity in the structure. Density functional theory calculations reveal a reduced bandgap energy after the formation of Co 3+ during desodiation of Na 1− y [Ni 2/3− x Co x Sb 1/3 ]O 2 . Using the oxidized Co 3+ species while improving the electrical conductivity, the Na[Ni 2/3− x Co x Sb 1/3 ]O 2 ( x = 1/6) electrode exhibits excellent cyclability for 1000 cycles with ≈72.5% capacity retention at 2C (400 mA g −1 ) and activity even at 50C (10 A g −1 ) in Na cells. Operando X‐ray diffraction and ex situ X‐ray absorption near‐edge structure investigations reveal suppressed lattice variations upon charge and discharge compared with those of Na[Ni 2/3 Sb 1/3 ]O 2 achieved by the presence of the electrochemical‐driven Co 3+ in the structure. These findings offer a new strategy for the development of cathode materials for sodium‐ion batteries, providing important insight into their structural transformations and the electronic nature of advanced cathode materials.
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