Suppressing Cation Migration and Reducing Particle Cracks in a Layered Fe-Based Cathode for Advanced Sodium-Ion Batteries
Suppressing Cation Migration and Reducing Particle Cracks in a Layered Fe-Based Cathode for Advanced Sodium-Ion Batteries
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抑制高级钠离子电池层状铁基阴极中的阳离子迁移并减少颗粒裂纹
DOI：
10.1002/smll.201904388
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发表时间：
2020
期刊：
影响因子：
13.3
通讯作者：
Zhou Haoshen
中科院分区：
文献类型：
--
作者：
Xu Jialu;Han Zhen;Jiang Kezhu;Bai Peilai;Liang Yue;Zhang Xiaoyu;Wang Peng;Guo Shaohua;Zhou Haoshen
钠离子电池在大规模储能应用中具有巨大的潜力。层状铁基氧化物由于其在地壳中的丰度和在电化学过程中的高活性而成为理想的正极材料之一。然而，铁离子向钠层的迁移是导致不可逆结构降解的主要障碍之一。本文揭示了循环过程中明显的铁离子迁移是导致局部强晶格应变和颗粒裂纹的主要原因，所有这些都导致了电化学性能的恶化。更重要的是，Ru掺杂策略可以有效抑制Fe离子的迁移，从而减少局部晶格应变和颗粒裂纹，从而大大提高钠的存储性能。原子尺度表征表明，循环后的NFO电极局部出现强烈的晶格应变，并伴有明显的颗粒裂纹。然而，钌掺杂的NFO电极通过抑制Fe-O畸变来保持有序的层状结构，从而消除了由此产生的副作用。结果表明，钌掺杂的NFO可提供120 mA h g−1的可逆容量，在100次循环后容量保持率约为80%，从而大大提高了其综合电化学性能。这一发现为设计高性能钠离子电池电极提供了新的思路。
Sodium‐ion batteries have huge potential in large‐scale energy storage applications. Layered Fe‐based oxides are one of the desirable cathode materials due to abundance in the earth crust and high activity in electrochemical processes. However, Fe‐ion migration to Na layers is one of the major hurdles leading to irreversible structural degradation. Herein, it is revealed that distinct Fe‐ion migration in cycling NaFeO2(NFO) should be mainly responsible for the strong local lattice strain and resulting particle cracks, all of which results in the deterioration of electrochemical performance. More importantly, a strategy of Ru doping could effectively suppress the Fe‐ion migration and then reduce the local lattice strain and the particle cracks, finally to greatly enhance the sodium storage performance. Atomic‐scale characterization shows that NFO electrode after cycling presents the intense lattice strain locally, accompanied by the remarkable particle cracks. Whereas, Ru‐doped NFO electrode maintains the well‐ordered layered structure by inhibiting the Fe–O distortion, so as to eliminate the resulting side effect. As a result, Ru‐doped NFO could greatly improve the comprehensive electrochemical performance by delivering a reversible capacity of 120 mA h g−1, about 80% capacity retention after 100 cycles. The findings provide new insights for designing high‐performance electrodes for sodium‐ion batteries.