镁二次电池用新型正极材料的设计、制备及性能研究

Developing highly efficient rechargeable batteries is crucial to alleviate the current energy and environmental problems. Due to their high specific energy, low cost, safe to handle and environmental benign, rechargeable magnesium batteries are promising candidates for stationary energy storage in‘heavy load’applications. However, rechargeable magnesium batteries are still plagued with two electron redox reaction of Mg2+ and the sluggish kinetics during the insertion/desertion of Mg2+, which leads to the low capacity and poor cycle life. This project intends to employ the concept to improve the performances of novel cathode materials in rechargeable magnesium batteries with great prospects. Starting from the viewpoint of molecular structure design, the binding energy between the anions/cations and Mg2+ in the electrode materials with three-dimensional network structure, will be calculated by density-functional theory (DFT) calculation and suitable electrode materials with special hierarchically conductive network will be designed, synthesized and investigated as the subjects, and their electrochemical reactions with Mg2+ will be studied by using the in-situ investigations in combination with quasi-in situ technologies. And the energy storage mechanism of the battery will be analyzed for further optimizing the electrochemical performances of electrode materials. Through constructing novel nano-electrode materials with three-dimensional network structure, prototype rechargeable magnesium batteries with high specific energy are expected, which may provide new ideas and theoretical basis for the scientific design of novel magnesium cathode materials.

发展高效稳定的二次电池储能技术是缓解能源及环境问题的关键支撑技术。在众多二次储能体系中，镁二次电池因其高比能、价廉、高安全、环境友好等优点，在大负荷储能方面具有广阔应用前景。目前束缚镁二次电池发展的瓶颈问题之一是基于双电子反应的镁离子在固体材料中迁移动力学缓慢，造成材料容量低，循环性能差等问题。本项目以发展具有潜在应用前景，优良性能的镁二次电池新型正极材料为目标，采用密度泛函理论计算不同网络框架结构材料内部孔道尺寸及阴阳离子与镁离子间相互作用，对材料进行初步理论筛选，根据筛选结果合成并构筑具有分级三维大孔道导电网络结构的新型纳米正极材料；利用原位、准原位化学和电化学表征技术研究电极反应过程，分析存储机理，探索改进镁二次电池电极反应的有效方法。通过设计三维大孔道网状结构的嵌入式新型纳米正极材料，获得高能量密度原型镁二次电池，为镁二次电池新型正极材料的科学设计提供新的思路和理论依据。

发展高效稳定的二次电池储能技术是缓解能源及环境问题的关键支撑技术。镁二次电池因其高比能、价廉、高安全、环境友好等优点，在大负荷储能方面具有广阔应用前景。目前束缚镁二次电池发展的瓶颈问题之一是基于双电子反应的镁离子在固体材料中迁移动力学缓慢，造成材料容量低，循环性能差等问题。在项目执行的三年期间,重点围绕如何改善镁离子迁移动力学缓慢的问题展开研究工作，分别开发出容量高、动力学性能好的层状正极材料以及具有快速传导镁离子能力的聚合物电解质，获得了高能量密度原型镁二次电池。并利用原位、准原位化学和电化学表征技术研究电极反应过程，分析存储机理，探索了改进镁二次电池电极反应的有效方法。此外，基于原位合金化反应的思路，通过设计并合成具有特殊支撑结构的基于原位合金反应的新型正极材料，分别在锂电池中初步评价了其电极反应历程后，在镁电池体系中进行了部分测试，表现出优越的储镁性能，为镁二次电池新型正极材料的科学设计提供新的思路和理论依据。