共价键碳修饰多组分金属磷化物复合材料的可控制备及其储钠机理研究

Despite the fact that transition metal phosphides have high theoretical specific capacity, their large-scale application as effective electrode materials for sodium-ion batteries has not yet been realized owing to their intrinsically low electronic conductivity and severe capacity fading caused by large volume variation upon cycling. To solve aforementioned critical issues that hamper the practical application of transition metal phosphides, an effective strategy that makes use of the in-situ transformation method was developed in this project to prepare covalent-bond carbon decorated metal phosphides composites to prevent severe pulverization and dissolution of phosphides during the charge and discharge process. Systematic study is carried out to investigate the formation mechanism of the covalent-bond carbon and subsequently analyze the synergistic effect imposed by the covalent-bond carbon on the phosphides, which will reveal the correlation between the stability at the interfaces and electrochemical performances. Meanwhile, the addition of foreign metal/non-metal elements to form multi-component metal phosphides composites is able to optimize the composition and electronic structure of the phosphides by improving their ion/electron transport. With the aid of various in-situ and ex-situ characterization techniques, the sodium storage mechanism of composites electrode can be revealed, which provides fundamental guidelines for developing high-performance electrode materials for sodium-ion batteries.

过渡金属磷化物虽然具有较高的理论比容量，然而较低的电子导电率以及循环过程中巨大体积效应导致了容量的大幅度衰减，严重限制了其作为钠离子电池电极材料的大规模应用。针对金属磷化物应用的关键性难题，本项目拟通过原位转化技术制备共价键碳修饰的金属磷化物复合材料，解决充放电过程中磷化物电极材料的破碎流失问题。系统研究磷化物表界面共价键碳的形成过程，分析共价键碳对金属磷化物的作用机理，揭示表界面稳定性与电化学性能之间的关系。同时，通过引入其它金属/非金属元素，从本质上优化其组分以及电子结构，进而实现多组分金属磷化物复合材料中电子和离子的快速传导。借助于各种原位/非原位表征技术，揭示复合电极材料的电化学储钠机理，为新型高性能钠离子电池电极材料的制备提供理论基础。

钠离子电池由于成本低、资源丰富，成为取代锂离子电池在大规模储能领域应用的理想选择。然而由于钠离子半径较大，在电极材料中嵌入/脱出动力学过程较慢，且会造成结构破坏，导致了容量的大幅度衰减，严重限制了钠离子电池的大规模应用。针对钠离子电池应用的关键性难题，本项目拟通过原位转化技术制备共价键碳修饰的钠离子电池复合电极材料，解决充放电过程中钠离子电池电极材料的破碎流失问题。通过引入其它金属/非金属元素，从本质上优化金属磷化物电极材料组分以及电子结构，进而实现多组分金属磷化物复合材料中电子和离子的快速传导。系统研究电极材料表界面共价键碳的形成过程，分析共价键碳对复合电极材料的作用机理，揭示表界面稳定性与电化学性能之间的关系。借助于各种原位/非原位表征技术，揭示复合电极材料的电化学储钠机理，为新型高性能钠离子电池电极材料的制备提供理论基础。