锡、锑硫化物@导电聚合物复合负极材料的可控构筑与储钠特性

无资源限制的钠离子电池适用于大规模储能体系，是极具研究价值与应用前景的新型二次电池，然而储钠负极材料一直是其应用瓶颈与研究重点。锡、锑硫化物基于可逆转化与合金化双重储钠机制，具有极高的理论比容量，然而由于其充放电过程中体积变化大、导电性差导致循环稳定性与倍率性能差，严重阻碍了其发展与实际应用。本项目拟设计合成中空/多孔锡、锑硫化物，再采用原位氧化聚合，制备锡、锑硫化物@导电聚合物复合材料。通过微纳化、多孔化、复合化、预钠化与掺杂效应改善材料的电子、离子传导性，缓冲充放电过程中体积变化产生的应力，提高材料的库伦效率，获得具有优异储钠性能的锡、锑硫化物负极材料；运用材料表征及电化学测量技术，结合第一性原理计算方法，研究元素掺杂对其性能的影响，深入探索锡、锑硫化物的储钠失效机理及其与导电聚合物的性能耦合机制，揭示材料的构性关系。本项目将为金属硫化物在钠离子电池中的应用提供理论基础与技术依据。

Sodium-ion batteries (NIBs) have attracted great attentions, particularly in large-scale electric energy storage applications due to the abundance of sodium sources. However, there remains a big challenge to develop high-performance anode materials for NIBs. Based on reversible conversion and alloy reaction, Sn, Sb sulfides have extremely high theoretical specific capacity. Thus, they are considered as promising anode materials for NIBs. However, Sn, Sb sulfides suffer from severe capacity fading and poor rate capability, which derive from the large volume change during the charge-discharge process as well as their poor conductivity. In this proposal, Sn, Sb sulfides with hollow or porous structure will be designed and synthesized. After that, Sn, Sb sulfides@conductive polymer composites will be prepared via in-situ oxidative polymerization. The benefits from micro/nanostructures, porous structure, composites, pre-sodiation, and doping are combined to enhance the diffusion of electrons and ions, to buffer the volume change during cycling, and to improve the coulombic efficiency. In that case, Sn, Sb sulfides@conductive polymer composites are expected to perform excellent electrochemical properties. Material characterizations and electrochemical measurements, combined with first principle calculation, are used to investigate the doping effects, the sodium storage mechanism of Sn, Sb sulfides, as well as the synergistic effects between Sn, Sb sulfides and conductive polymers. This project will provide a theoretical and technical basis for metal sulfides as anode materials for sodium ion batteries.