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阴离子大小不匹配和电荷相互作用驱动在矿矿表面的剂分离
Wonyoung Lee1, Jeong Woo Han, Yan Chen
1Laboratory for Electrochemical Interfaces, Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.
Journal of the American Chemical Society
|May 7, 2013
概括
了解固体氧化物燃料电池 (SOFC) 阴极中的离子分离是性能的关键. 这项研究揭示了弹性和静电力驱动分离,Ca-doped LaMnO3显示出更好的SOFC最稳定的表面.
科学领域:
- 材料科学 材料科学 材料科学
- 电化学 电化学 电化学
- 表面科学是一门学科.
背景情况:
- 矿氧化物表面上的阴离子分离显著影响固氧化物燃料电池 (SOFC) 阴极的氧降低活性和稳定性.
- 解释离子分离的物理起源的统一理论对于设计具有优化表面化学的先进阴极材料至关重要.
研究的目的:
- 量化评估驱动在氧化物表面上 dopant 分离的弹性和静电相互作用.
- 开发预测能力,以定制阴极表面组成,以提高SOFC性能.
主要方法:
- 结合表面化学分析 (X射线光电子和奥格尔电子光谱) 在模型薄膜上进行计算分析 (密度函数理论和分析模型).
- 系统地改变剂半径和充电空隙分布,以诱导弹性和静电能量差异.
- 研究了氧气化学潜力的对分离机制的影响.
主要成果:
- 补充剂分离是由弹性和静电能量的贡献驱动的.
- 较小的阴离子尺寸不匹配和化学扩展的格子减少了剂分离,从而导致更稳定的阴极表面.
- 在Ca-doped LaMnO3中,表现出最稳定的表面组成,离子分离最小.
- 较大的剂 (Ba, Sr) 显示出较慢的扩散动力学,在较低的温度下动力学上捕获分离.
- 分离的多氧化物形成了电子绝缘的表面异质性.
结论:
- 这项研究提供了定量证据,证明了弹性和静电力在矿氧化物上离子分离中的联合作用.
- 优化补充剂-宿主离子大小不匹配和晶格扩张可以最大限度地减少分离并提高阴极稳定性.
- 通过控制表面化学,这些发现为设计高性能SOFC阴极材料提供了预测框架.
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