从空气电池阴极释放单片氧气的新见解:定期DFT与CASPT2嵌入式集群计算
Francesca Fasulo1, Arianna Massaro2, Ana B Muñoz-García1,3
1Department of Physics "E. Pancini", University of Naples Federico II, I-80126 Napoli, Italy.
Journal of chemical theory and computation
|July 11, 2023
概括
在Li-air电池充电期间单点氧 (1O2) 释放是一个主要问题. 这项研究揭示了一种可行的超氧化物中介机制,用于1O2形成,提供了控制其有害影响的策略.
科学领域:
- 电化学 电化学 电化学
- 材料科学 材料科学 材料科学
- 理论化学 理论化学
背景情况:
- 空气 (Li-air) 电池具有高能量密度,但由于反应性单片氧 (1O2) 形成而面临挑战.
- 了解1O2生成机制对于减轻电解质降解和提高电池性能至关重要.
- 对于像密度函数理论这样的标准方法来说,单点氧化学的准确理论建模是复杂的.
研究的目的:
- 调查Li-空气电池充电期间Li2O2表面单片氧 (1O2) 形成的反应机制.
- 阐明超氧化物中间体在氧化过程中的作用.
- 为控制利氧气电池中有害的1O2演变提供见解.
主要方法:
- 采用嵌入式集群方法,将CASPT2和高精度计算的有效点收费结合起来.
- 研究了 (112̅0) -Li2O2表面末端的氧化.
- 分析了单次氧释放的潜在能量表面 (PES).
主要成果:
- 确定了一个稳定的超氧化物中间体作为1O2释放的PES上的局部最小值,这是周期性DFT错过的特征.
- 描绘了可行的O22−/O2−/O2反应机制,用于1O2的形成.
- 证实1O2释放可以通过两步一电子过程或一步两电子机制发生,其中包括超氧化物中间体.
结论:
- 在充电过程中从Li2O2中单点释放氧气是可行的,通过涉及超氧化物中间体的途径.
- 超氧化物中间体的稳定性是控制1O2形成的关键因素.
- 调整超氧化物稳定性是开发高性能和稳定的Li-air电池的可行策略.
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