材料科学
氧化还原
阴极
分析化学(期刊)
电导率
电阻率和电导率
化学
冶金
物理化学
物理
色谱法
量子力学
作者
Suo He,Xing Shen,Moonsik Han,Yanshun Liao,Lifeng Xu,Ning Yang,Yiming Guo,Bochen Li,Jie Shen,Cheng Zha,Yali Li,Meng Wang,Lian Wang,Yuefeng Su,Feng Wu
出处
期刊:ACS Nano
[American Chemical Society]
日期:2024-04-17
标识
DOI:10.1021/acsnano.4c01263
摘要
P2-NaxMnO2 has garnered significant attention due to its favorable Na+ conductivity and structural stability for large-scale energy storage fields. However, achieving a balance between high energy density and extended cycling stability remains a challenge due to the Jahn-Teller distortion of Mn3+ and anionic activity above 4.1 V. Herein, we propose a one-step in situ MgF2 strategy to synthesize a P2-Na0.76Ni0.225Mg0.025Mn0.75O1.95F0.05 cathode with improved Na-storage performance and decent water/air stability. By partially substituting cost-effective Mg for Ni and incorporating extra F for O, the optimized material demonstrates both enhanced capacity and structure stability via promoting Ni2+/Ni4+ and oxygen redox activity. It delivers a high capacity of 132.9 mA h g-1 with an elevated working potential of ≈3.48 V and maintains ≈83.0% capacity retention after 150 cycles at 100 mA g-1 within 2-4.3 V, compared to the 114.9 mA h g-1 capacity and 3.32 V discharging potential of the undoped Na0.76Ni0.25Mn0.75O2. While increasing the charging voltage to 4.5 V, 133.1 mA h g-1 capacity and 3.55 V discharging potential (vs Na/Na+) were achieved with 72.8% capacity retention after 100 cycles, far beyond that of the pristine sample (123.7 mA h g-1, 3.45 V, and 43.8%@100 cycles). Moreover, exceptional low-temperature cycling stability is achieved, with 95.0% after 150 cycles. Finally, the Na-storage mechanism of samples employing various doping strategies was investigated using in situ EIS, in situ XRD, and ex situ XPS techniques.
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