Suppression of voltage-decay in Li2MnO3 cathode via reconstruction of layered-spinel coexisting phases,Journal of Materials Chemistry A

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Suppression of voltage-decay in Li2MnO3 cathode via reconstruction of layered-spinel coexisting phases
Journal of Materials Chemistry A ( IF 10.7 ) Pub Date : 2020-08-11 , DOI: 10.1039/d0ta05101b
Jue Wu _{1,

2,

3,

4,

5} , Zehao Cui _{1,

2,

3,

4,

5} , Jinpeng Wu _{6,

7,

8,

9} , Yuxuan Xiang _{1,

2,

3,

4,

5} , Haodong Liu _{9,

10,

11,

12} , Shiyao Zheng _{1,

2,

3,

4,

5} , Wanli Yang _{6,

7,

8,

9} , Yong Yang _{1,

2,

3,

4,

5}

Affiliation

Voltage decay, i.e., the voltage decrease during electrochemical cycling, has been a decade-long challenge for lithium-ion batteries. This issue not only leads to a substantial loss of energy density, but also raises challenges for the battery management system, hindering the commercial application of high capacity lithium-rich oxide. Here, we show that through a combination of electrochemical conditioning and thermal treatment, Li₂MnO₃, the parent compound of lithium-rich oxide, which typically displays severe voltage and capacity decay, could be converted into a new phase that essentially suppresses the voltage decay with improved capacity retention and rate performance. By combining atomic-sensitive nuclear magnetic resonance, differential electrochemical mass spectrometry and synchrotron-based resonant inelastic X-ray scattering, we disclose that treatment triggers the formation of three-coexisting phases, i.e., the lithium-rich layered, spinel and defect spinel phases, which enables improved reversibility of the oxygen redox activity and enhanced manganese redox reactions in the initial cycle. Our findings suggest the key role of the local structure in the voltage decay problem and provide insights for material optimizations towards lithium- and manganese-rich cathodes without the voltage decay.

中文翻译：

层状尖晶石共存相的重构抑制Li2MnO3阴极的电压衰减

对于锂离子电池来说，电压衰减，即电化学循环过程中的电压下降，已经是十年来的挑战。这个问题不仅导致能量密度的大量损失，而且对电池管理系统提出了挑战，阻碍了高容量富锂氧化物的商业应用。在这里，我们表明通过电化学调节和热处理相结合，Li ₂ MnO ₃，通常表现出严重的电压和容量衰减的富锂氧化物的母体化合物可以转换成新相，该相基本上可以抑制电压衰减，并改善容量保持率和速率性能。通过结合原子敏感的核磁共振，差分电化学质谱法和基于同步加速器的共振非弹性X射线散射，我们揭示了处理触发了三个共存相的形成，即，富含锂的层状，尖晶石和缺陷尖晶石相，可以在初始循环中改善氧氧化还原活性的可逆性并增强锰氧化还原反应。我们的研究结果表明了局部结构在电压衰减问题中的关键作用，并为在不发生电压衰减的情况下针对富含锂和锰的阴极的材料优化提供了见识。

更新日期：2020-09-22

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