An in situ dual-modification strategy for O3-NaNi_1/3Fe_1/3Mn_1/3O₂ towards high-performance sodium-ion batteries

Abstract

The V-modified NFM that couples broader Na+ diffusion layer with interface shielding is successfully in situ synthesized to exhibit a high rate capacity and excellent cycling stability with 75.8% capacity retention for 500 cycles for SIBs.

A high-rate and air-stable cathode material for sodium-ion batteries: yttrium-substituted O3-type Ni/Fe/Mn-based layered oxides

“…This indicates that Y 3+ substitution can effectively improve the rate capability of NFM, which is due to the expanded d -spacing between the TM slabs. In addition, the rate capability at 5C of NFMY1 in our work and the modified NFM in published papers was compared, 4,37,49,57,59–67 and the results are shown in Fig. 5.…”

“…The cell volume v of the NFM material changed by 8.4% before and after charge and discharge, while that of NFMY1 only changed by 0.05%, indicating that Y 3+ substitution effectively inhibited crystal cracking behavior, which could be attributed to inhibiting lattice distortion and reducing local internal stress caused by volume expansion/contraction during charge and discharge, which significantly improves the cycling stability of the material. 59…”

Manipulating Local Chemistry and Coherent Structures for High-Rate and Long-Life Sodium-Ion Battery Cathodes

“…Conversely, the (10 l ) peaks associated with both the P2 and O3 phase are moved toward a higher angle, indicative of the contraction of the a / b -axis driven by the stronger TM–O bonding energy and smaller ionic radius as the escalation in the valence state of reactive TM cations. The intensity of the (003) and (104) peaks of the O3 phase is gradually weakened and eventually vanished with further Na + extraction, which is speculated to be the emergence of the P3 phase as a result of an O3–P3 structural transition, a common occurrence for O3-type cathode materials during desodiation process . With regard to the P2 phase, the peaks are well maintained up to about 4.08 V except for continuous shifts, indicative of the solid solution behaviors .…”

Status and prospects of O3-type layered oxide cathodes for Na-ion batteries: stability, reversibility, and reaction mechanism

“…Ni/Fe/Mn 基正极材料(NFM)更吸引研究者的注意。 Fe 引入 TMO2 层，可以促进电子离域，扩大 TMO2 层 间距。Yuan [77] 等通过溶胶-凝胶法合成了一系列 Fe 取 代的 Na(Ni0.5Mn0. [78] 。低镍含量的 O3-Na[Ni0.3Fe0.2Mn0.5]O2 在 2.0-4.2 V 的电压区间内可提供 139 mAh/g 的可逆比容量，100 次循环后容量保持率 77%，但 Mn 3+ /Mn 4+ 较低的氧化还原电位导致材料只有 较低的能量密度 [79] 。此外，适当降低 Ni 含量，提升 Fe 含量能在牺牲少量容量的前提下显著提高 NFM 的循 环稳定性和热稳定性， 这主要是因为 Fe 元素能够稳定 晶格氧，抑制不可逆的氧损失 [80] 。但 Fe 含量过高也会 导致材料电化学性能的的降低，这与 Fe 3+/4+ 的不可逆 氧化还原和 Fe 向 Na 层的不可逆迁移有关 [81] 。因此平 衡好 O3-NFM 体系中 Ni/Fe/Mn 的相对含量，是取得 高性能正极材料的关键。 目前，O3-NaNi1/3Fe1/3Mn1/3O2 正极(NFM111)凭 借较高的可逆比容量和良好的循环稳定性的优势，成 为率先取得商业化的第一代 NFM 正极材料 [82] 。 Wang [83] [84] 。电荷补偿方 面， NFM111 材料主要由 Ni 2+/4+ 和 Fe 3+/4+ 氧化还原对提 供容量，Mn 表现为电化学惰性， Ni/Fe 参与电荷补偿 的程度随正极 Na + 浓度变化而变化(图 7d) [85] 。总体 而言，NFM111 正极实现了容量、工作电压和稳定性 的平衡，是目前主要的商业化钠电正极材料。尽管如 此，O3 相材料存在的相变复杂，循环稳定性和空气稳 定性差等缺点仍是 NFM111 正极亟待解决的难题。大 量的研究表明，元素掺杂(例如 Al，Cu，Ti，Mg，Zn 和 V 等) [86][87][88]…”