Influence of Na/Mn arrangements and P2/P′2 phase ratio on the electrochemical performance of NaxMnO2 cathodes for sodium-ion batteries,Journal of Materials Chemistry A

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Influence of Na/Mn arrangements and P2/P′2 phase ratio on the electrochemical performance of NaxMnO2 cathodes for sodium-ion batteries
Journal of Materials Chemistry A ( IF 10.7 ) Pub Date : 2020/03/02 , DOI: 10.1039/c9ta12176e
Andrzej Kulka _{1,

2,

3,

4,

5} , Cyril Marino _{4,

5,

6} , Katarzyna Walczak _{1,

2,

3} , Camelia Borca _{4,

6,

7} , Christoph Bolli _{4,

5,

6} , Petr Novák _{4,

5,

6} , Claire Villevieille _{8,

9,

10,

11}

Affiliation

Among the candidate cathode materials for sodium-ion batteries (SIBs), Na_xMnO₂ (NMO) layered oxides are especially attractive in terms of working potential (ca. 3.0 V vs. Na⁺/Na) and high initial specific charge. In this work we discuss the influence of the sodium/manganese arrangements in P2 and P′2-type phases and P2/P′2 phase ratio on the electrochemical performance of NMO electrodes. The detailed structural characterization of the materials was achieved by X-ray diffraction (XRD), neutron powder diffraction (NPD), inductively coupled plasma (ICP), and scanning electron microscopy (SEM/EDS). By combining the results from X-ray absorption spectroscopy (XAS), operando XRD, and online electrochemical mass spectrometry (OEMS) techniques we found that it is possible to change the reaction mechanisms from the P2 + P′2-type → OP4-type phase (observed for biphasic P2/P′2 Na_xMnO₂) to an intergrowth mechanism (single P2 Na_xMnO₂) by tuning the pristine composition. Additionally, we further discuss the influence of the reaction mechanism on the electrochemical performance. Based on the standard cycling protocol and rate capability tests we found that appropriate synergy of both P2 and P′2 is essential for obtaining Na_xMnO₂ electrodes with high specific charge offering long-term cycling.

中文翻译：

Na / Mn排列和P2 / P′2相比对钠离子电池NaxMnO2阴极电化学性能的影响

在钠离子电池（SIB）的候选阴极材料中，Na _x MnO ₂（NMO）层状氧化物在工作电势（约3.0 V对Na ⁺ / Na）和高初始比电荷方面特别有吸引力。在这项工作中，我们讨论了P2和P'2型相中钠/锰排列以及P2 / P'2相比对NMO电极电化学性能的影响。通过X射线衍射（XRD），中子粉末衍射（NPD），电感耦合等离子体（ICP）和扫描电子显微镜（SEM / EDS）实现了材料的详细结构表征。通过结合X射线吸收光谱（XAS）的结果，进行操作XRD和在线电化学质谱（OEMS）技术发现，可以从P2 + P′2型→OP4型相改变反应机理（对于双相P2 / P′2 Na _x MnO ₂观察到）通过调节原始成分来达到共生机理（单一P2 Na _x MnO ₂）。此外，我们进一步讨论了反应机理对电化学性能的影响。基于标准循环协议和速率能力测试，我们发现P2和P'2的适当协同作用对于获得具有高比电荷并提供长期循环的Na _x MnO ₂电极至关重要。

更新日期：2020-03-26

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