基于碳/氮族二维材料负载Pt/Pd单原子的锂氧电池正极体系氧析出催化机理研究

The proposal of Pt/Pd single atom catalysts (SACs) and the development of Group-IV/V two-dimensional supporters, such as silicene and phosphorene has brought new opportunities to solve the problems of high Li2O2 decomposition potential in Li-O2 batteries. Over the past few years, many studies have focused on the preparation and performance characterizations of SACs. However, the effect of the unique electronic properties of Pt/Pd single atom on the OER catalytic mechanism remains essentially unclear. In this project, by using the first-principles calculations, molecular dynamics simulations combined with the experimental verifications, we aim to uncover the changing effects of the coordination environment and electronic structure of different defect or B/N/S-doped 2D supporters (graphene, silicene and phosphorene) on the adsorption properties of Pt/Pd SACs, and their interfacial bonding performance with Li2O2. Moreover, we expect to reveal the connections between the structural/electronic properties of the 2D materials supporting SACs and the desorption choice of the decomposition products, such as Li+, O2, as well as the catalytic reaction barrier of OER. It then proposes optimized strategies for co-regulating the catalytic activity and stability of Pt/Pd SACs by Group-IV/V 2D supporters, thus providing more practical suggestions on studying SACs supported by 2D materials.

Pt/Pd单原子催化剂的提出与硅烯、磷烯等碳/氮族二维载体的发展为解决锂氧电池Li2O2高分解电位问题带来新机遇。在过去几年中，已有一些研究集中于负载型单原子催化剂的制备和性能表征，但就单原子体系独特的结构与性质对氧析出(OER)催化机制的影响需要更为全面的认识。本项目基于石墨烯、硅烯、磷烯负载Pt、Pd单原子锂氧电池正极材料的构筑，采用第一性原理计算、分子动力学模拟并结合实验验证，探索缺陷/掺杂(硼、氮、硫掺杂及共掺)改性的二维载体配位环境、电子结构等性质的变化对Pt、Pd单原子吸附及其与Li2O2界面接合性能的影响机理，揭示二维材料负载单原子催化剂结构/电子特性与Li+、O2等分解产物的脱附选择性及OER催化反应势垒之间的关联规律，提出碳/氮族二维载体对Pt/Pd单原子OER催化活性及稳定性进行协同调控的优化方案，为二维材料负载单原子催化剂实用化研究提供指导和思路。

硅烯、磷烯等碳/氮族二维材料负载Pt/Pd单原子催化剂的提出为解决锂氧电池Li2O2高分解电位问题带来新机遇。迫切需要从调控电极微观结构、电荷转移等的角度，有机地融合理论、计算和实验方法，对包含锂氧电池等二次电池中充放电电压、比容量以及结构稳定性等方面开展系统的研究工作。本项目则首先从配位场理论方法出发并结合可直接计算电子分布及占据特性的第一性原理计算方法，对二次电池充放电过程中决定电压的费米能级计算模型、衡量相结构稳定性的晶体场稳定化能计算公式、调控阴离子氧化还原活性的理论模型等进行了严格的推导。在此基础上，提出针对刚性带体系的电压调控和含不同周期元素相结构稳定性预测等一系列电极能量密度/相稳定性改进策略，并成功设计出无过渡金属LiBCF2正极材料。本项目拓展了配位场理论在离子嵌入电化学中的应用，为后续从电子的能带调控角度设计高能量密度嵌入式电极材料提供思路。发表Natl. Sci. Rev., Chem. Rev.等SCI论文17篇，在《储能科学与技术》发表特约论文1篇；国内外学术会议邀请/口头报告9次，获优秀口头报告奖3次；培养硕士毕业生2名、在读硕士生7名。