Restraining Oxygen Release and Suppressing Structure Distortion in Single-Crystal Li-Rich Layered Cathode Materials,Advanced Functional Materials

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Restraining Oxygen Release and Suppressing Structure Distortion in Single-Crystal Li-Rich Layered Cathode Materials
Advanced Functional Materials ( IF 18.5 ) Pub Date : 2021-11-27 , DOI: 10.1002/adfm.202110295
Jianming Sun _{1,

2} , Chuanchao Sheng ₃ , Xin Cao _{1,

2} , Pengfei Wang ₃ , Ping He ₃ , Huijun Yang ₁ , Zhi Chang ₁ , Xiyan Yue ₄ , Haoshen Zhou _{1,

2,

3}

Affiliation

Li-rich oxides can be regarded as the next-generation cathode materials for high-energy-density Li-ion batteries since additional oxygen redox activities greatly increase output energy density. However, the oxygen loss and structural distortion induce low initial coulombic efficiency and severe decay of cycle performance, further hindering their industrial applications. Herein, the representative layered Li-rich cathode material, Li_1.2Ni_0.2Mn_0.6O₂, is endowed with novel single-crystal morphology. In comparison to its polycrystal counterpart, not only can serious oxygen release be effectively restrained during the first oxygen activation process, but also the layered/spinel phase transition can be well suppressed upon cycling. Moreover, the single-crystal cathode exhibits the limited volume change and persistent presence of superlattice peaks upon Li⁺ (de)intercalation processes, resulting in enhanced structural stability with absence of crack generation and successive utilization of oxygen redox reaction during long-term cycling. Benefiting from these unique features, the single-crystal Li-rich electrode not only yields a high reversible capacity of 257 mAh g⁻¹, but also achieves excellent cycling performance with 92% capacity retention after 200 cycles. These findings demonstrate that the morphology design of single crystals can be regarded as an effective strategy to realize high-energy density and long-life Li-ion batteries.

中文翻译：

抑制单晶富锂层状正极材料的氧释放和结构畸变

富锂氧化物可被视为高能量密度锂离子电池的下一代正极材料，因为额外的氧氧化还原活性大大提高了输出能量密度。然而，氧损失和结构变形导致初始库仑效率低和循环性能严重衰减，进一步阻碍了它们的工业应用。这里，代表层状富锂正极材料，Li _1.2 Ni _0.2 Mn _0.6 O ₂, 具有新颖的单晶形态。与其多晶对应物相比，不仅可以在第一次氧活化过程中有效地抑制严重的氧释放，而且在循环时可以很好地抑制层状/尖晶石相变。此外，单晶正极在 Li ⁺ (de) 嵌入过程中表现出有限的体积变化和超晶格峰的持续存在，从而提高了结构稳定性，在长期循环过程中不会产生裂纹和连续利用氧氧化还原反应。得益于这些独特的特性，单晶富锂电极不仅具有 257 mAh g ^{-1的高可逆容量}，而且在 200 次循环后也实现了出色的循环性能，容量保持率为 92%。这些发现表明，单晶的形貌设计可以被视为实现高能量密度和长寿命锂离子电池的有效策略。

更新日期：2021-11-27

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