二氧化碳共电解氧电极材料分子模拟设计及微通道界面优化

Flexible nuclear power for clean fuels and peak electricity production by co-electrolysis of CO2 and H2O/fuel cell technology(HTEFC), which can extend the novel uses of nuclear plant to decrease CO2 emission, enable large-scale energy storage and load-following capability, is the cutting-edge research frontier for nuclear energy around the world. While technically feasible and carries the above-mentioned advantages in concert with nuclear energy, operation in electrolytic mode to enable the HTEFC has thus far been challenged by the degradation of electrode materials. The low activity and durability of oxygen electrodes are primarily responsible for the loss in efficiency. In this project, the research will focus on the development of oxygen electrodes for HTEFC. Interface can be strengthened by preparing micro-channel base strucuture with directional design to avoide delamination. Novel Ruddlesden Popper type materials with over oxygen stoichiometry will be identified and modeled by predictive molecular simulations, and investigated by surface sensitive experiments and laboratory tests. The oxygen electode with high interfacial strength and low area resistance under oxygen partial pressure over a wide range can be prepared through the combination of micro-channel base and gradient RP composites. The reaction and degradation mechanisms in molecular level are described by the development of atomic-level interface models and experiments. Results will identify: 1) the CO2-related degradation modes of materials in HTEFC, and material design strategies to improve durability, and 2) the relations of material structure to its reactivity with oxygen in a reversible manner for micro-channel electrode, to improve activity and efficiency. Ultimate purpose is to enhance the activity and duraibility of oxygen electrodes, and the durabiltiy of the H2O+CO2 electrode. The research achievements can not only provide theoretical data and establish technical foundation for the further study and application of this novel technology but also enhance the understanding of interfacial behavior of the complexes porous electrode as well as promote the scientific research development of high temperature solid state electrochemistry.

利用核能灵活驱动高温共电解CO2 和H2O/燃料电池（HTEFC）实现清洁燃料制备和峰值发电，可提高核能经济性及在储能和CO2减排方面的新应用，促进可再生能源并入电网，是国际核能领域的前沿课题。然而如何控制性能衰减，尤其是共电解过程中氧电极活性偏低和耐候性差是限制HTEFC实用化的关键。基于此，本项目以HTEFC氧电极材料为研究对象，定向设计合成新型微通道结构以强化界面减少脱层，并结合RP型高氧化学计量数活性材料的梯度复合，开发高界面强度和宽氧范围内低极化阻抗的氧电极。通过开展原子尺度的结构计算和实验研究，在分子水平程度描述反应和衰减的机制。研究结果将明确：1）在HTEFC运行环境下，与二氧化碳相关的材料衰减模式，材料设计的策略以提高耐候性，2）微通道电极，材料的结构及其与氧分压之间的关系，提高活性和效率。研究成果可加深对复杂多孔电极界面行为的理解，并推动高温固态电化学科学相关研究的发展。

本课题的研究目标是研究高温共电解模式下材料的衰减模式，通过材料设计制备高活性和稳定性的微通道氧电极，提高电极活性和效率。课题在四个方面取得重要的工作进展：（1）通过分子模拟，对Pr 或Nd 掺杂的Ruddlesden-Popper 系列中La2NiO4+δ 层状氧电极材料的分子动力学、热力学和电子过程进行深入研究和理解，在此基础上筛选出了一系列高活性的HTCE氧电极材料，并对其材料和电性能进行了系统研究；（2）提出了一种新型的微通道氧电极的制备方法，研究了固体含量、添加剂、冷冻温度、冷冻速率和烧结温度等对基体机械强度及结构的影响，最终得到了高活性和稳定性的微通道结构氧电极。（3） 研究了不同影响因素对共电解模式下SOEC的性能作用规律，揭示了影响电极性能的关键影响因素，即CO2的转化和扩散；对RP型的氧电极的表面反应动力学进行了深入分析，发现Sr的偏析是影响氧电极性能的重要因素；（4）通建立了HTEFC总效率的计算模型，从热力学和电化学的角度系统研究了高温共电解效率的影响因素以及产物的调控规律，该研究可为HTCE的运行提供指导和依据。