Competition between the Ni and Fe Redox in the O3-NaNi1/3Fe1/3Mn1/3O2 Cathode Material for Na-Ion Batteries,Chemistry of Materials

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Competition between the Ni and Fe Redox in the O3-NaNi1/3Fe1/3Mn1/3O2 Cathode Material for Na-Ion Batteries
Chemistry of Materials ( IF 7.2 ) Pub Date : 2023-05-04 , DOI: 10.1021/acs.chemmater.3c00338
Vitalii A. Shevchenko _{1,

2} , Iana S. Glazkova _{1,

3} , Daniil A. Novichkov ₁ , Irina Skvortsova _{2,

4} , Alexey V. Sobolev _{1,

3} , Artem M. Abakumov ₂ , Igor A. Presniakov ₁ , Oleg A. Drozhzhin ₁ , Evgeny V. Antipov _{1,

2}

Affiliation

Sodium-ion batteries are attracting great attention due to their low cost and abundance of sodium. The O3-type NaNi_1/3Fe_1/3Mn_1/3O₂ layered oxide material is a promising candidate for positive electrodes (cathodes) in Na-ion batteries. However, its stable electrochemical performance is restricted by the upper voltage limit of 4.0 V (vs Na/Na⁺), which allows for reversibly removing 0.5–0.55 Na⁺ per formula unit, corresponding to the capacity of 120–130 mAh·g^–1. Further reduction of sodium content inevitably accelerates capacity degradation, and this issue calls for a detailed study of the redox reactions that accompany the electrochemical (de)intercalation of a large amount of sodium. Here, we present operando and ex situ studies using powder X-ray diffraction and X-ray absorption spectroscopy combined with ⁵⁷Fe Mössbauer spectroscopy. Our approach reveals the sequence of the redox transitions that occur during the charge and discharge of O3-NaNi_1/3Fe_1/3Mn_1/3O₂. Our data show that in addition to nickel and iron cations oxidizing to M⁺⁴, a part of iron transforms into the “3 + δ” state owing to the fast electron exchange Fe³⁺ + Fe⁴⁺ ↔ Fe⁴⁺ + Fe³⁺. This process freezes upon cooling the material to 35 K, producing Fe⁴⁺ cations, some of which occupy tetrahedral positions.

中文翻译：

O3-NaNi1/3Fe1/3Mn1/3O2钠离子电池正极材料中Ni和Fe氧化还原的竞争

钠离子电池因其低成本和丰富的钠元素而备受关注。O3型NaNi _1/3 Fe _1/3 Mn _1/3 O ₂层状氧化物材料是一种很有前途的钠离子电池正极（正极）材料。然而，其稳定的电化学性能受到电压上限 4.0 V（vs Na/Na ⁺）的限制，这允许每个配方单元可逆地去除 0.5–0.55 Na ⁺，对应于 120–130 mAh·g 的容量^{– 1个}. 进一步降低钠含量不可避免地会加速容量退化，这个问题需要详细研究伴随大量钠的电化学（脱）嵌入的氧化还原反应。在这里，我们使用粉末 X 射线衍射和 X 射线吸收光谱结合⁵⁷ Fe Mössbauer 光谱进行原位和非原位研究。_{我们的方法揭示了 O3-NaNi 1/3} Fe _1/3 Mn _1/3 O ₂充电和放电期间发生的氧化还原转变的顺序。我们的数据表明，除了镍和铁阳离子氧化成 M ⁺⁴外，部分铁由于快速电子交换 Fe ^{3+而转变为“3 + δ”状态}+ Fe ⁴⁺ ↔ Fe ⁴⁺ + Fe ³⁺。该过程在将材料冷却至 35 K 时冻结，产生 Fe ⁴⁺阳离子，其中一些占据四面体位置。

更新日期：2023-05-04

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