材料科学
阴极
法拉第效率
相(物质)
离子
结晶学
电化学
八面体
穆斯堡尔谱学
价(化学)
分析化学(期刊)
晶体结构
化学
电极
物理化学
有机化学
色谱法
作者
Jie Feng,Shaohua Luo,Lihua Qian,Shengxue Yan,Qing Wang,Xianbing Ji,Yahui Zhang,Xin Liu,Pengqing Hou,Fei Teng
出处
期刊:Small
[Wiley]
日期:2023-02-20
卷期号:19 (20)
被引量:11
标识
DOI:10.1002/smll.202208005
摘要
Abstract P 2 layered oxides have attracted more and more attention as cathode materials of high‐power sodium‐ion batteries (SIBs). During the charging process, the release of sodium ions leads to layer slip, which leads to the transformation of P 2 phase into O 2 phase, resulting in a sharp decline in capacity. However, many cathode materials do not undergo P 2 ‐O 2 transition during charging and discharging, but form a “Z” phase. It is proved that the iron‐containing compound Na 0.67 Ni 0.1 Mn 0.8 Fe 0.1 O 2 formed the “Z” phase of the symbiotic structure of the P phase and O phase during high‐voltage charging through ex‐XRD and HAADF‐STEM. During the charging process, the cathode material undergoes a structural change of P 2 ‐OP 4 ‐O 2 . With the increase of charging voltage, the O‐type superposition mode increases to form an ordered OP4 phase, and the P 2 ‐type superposition mode disappears after further charging to form a pure O 2 phase. 57 Fe‐Mössbauer spectroscopy revealed that no migration of Fe ions is detected. The O–Ni–O–Mn–Fe–O bond formed in the transition metal MO 6 (M = Ni, Mn, Fe) octahedron can inhibit the elongation of the Mn–O bond and improve the electrochemical activity so that P2‐Na 0.67 Ni 0.1 Mn 0.8 Fe 0.1 O 2 has an excellent capacity of 172.4 mAh g −1 and a coulombic efficiency close to 99% at 0.1C.
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