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

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.

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。

钠离子电池具有与锂离子电池相似的工作原理，且钠资源丰富，因而在大规模储能领域，钠离子电池被认为是最有可能取代锂离子电池的新型二次电池。负极材料作为钠离子电池的关键组成部分，其性能是其实现广泛应用的瓶颈。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。. 本项目研究了锡、锑硫化物基复合材料的多种制备方法。采用水热法成功制备了Sb2S3空心微米球、采用球磨法成功制备了SnS2/石墨烯复合材料，并采用静电纺丝法制备了Sb2S3/C复合纳米纤维、SnS2/C复合纳米纤维、柔性自支撑的SnS/C复合纳米纤维膜等多种复合材料。此外，还研究了碳材料、导电聚合物、TiO2等多种材料对Sn、Sb基硫化物与化合物的复合改性，研究了材料的储钠机制，阐明了多种复合材料的耦合性能改善机制。制备的SnS/C复合纳米纤维膜作为钠离子电池自支撑电极，在50mA/g的电流密度下循环100次，仍有481mAh/g的放电比容量。此外，SnS/C纳米纤维膜还具有长达500次循环的超长循环寿命。制备的Sb2S3/C复合材料在电压范围为0.01-2.0V(vs.Na/Na+)，电流密度为200mA/g时，循环200次后，放电比容量为321mAh/g。. 在本项目资助下，发表了相关SCI 论文11篇，获得了4项国家发明专利授权。培养了硕士研究生11名。