嵌钠SnS2负极材料纳米Sn粗化抑制及转化反应可逆性研究

Rechargeable sodium ion batteries (SIBs) have been considered as one of the promising technologies for large-scale energy storage in the future. The technical challenge for intercalation chemistry SIBs is, however, the difficulty of accommodating larger Na+ ions in the appropriate hosting electrode materials. Therefore, the development of electrode materials with high Na+ ions storage capacity and stability is vital to the development of high performance SIBs. SnS2 has been considered as a promising anode material of SIBs for its high Na+ ions storage capacity. However, the application of SnS2 anode has been constrained for its fast specific capacity degradation during the sodiation/desodiation cycling process. In previous study the applicant has demonstrated that the reduced Sn/Na2S conversion reaction interfaces caused by Sn coarsening is responsible for the poor cycling stability of SnS2 anode materials. In this project, to solve this problem, the kinetics of Sn coarsening under different driving forces, as well as their influence on the interface reactivity of Sn/Na2S interfaces during sodiation/desodiation cycling of SnS2 will be studied. A novel strategy-adding transition metal M in SnS2-C composite and creating SnS2-MS2 heterostructures to suppress the Sn coarsening and thus enhance the reversibility of conversion reaction, has been proposed. The roles of each component in (SnM)S2-C system for the enhancement of sodiation/desodiation reversiblity and cycleability of electrode will be elucidated. We hope that it can provide new insight for the development of novel SnS2 based anode materials with high specific capacity and long-term cycling stability, and enrich the possibilities of developing other high performance metal chalcogenides based anode materials for SIBs.

钠离子电池被认为是下一代大规模储能技术的理想选择之一，然而较大的离子半径易导致负极材料在脱嵌钠过程中结构“坍塌”和粉化，开发能够快速稳定储钠的负极材料已成为钠离子电池发展的关键。SnS2具有优异的储钠能力，是一种很有应用前景的负极材料，但是在嵌/脱钠循环过程中存在容量衰减过快的问题。申请人前期研究发现，嵌钠过程中纳米Sn粗化导致的Sn/Na2S转化反应界面减少是SnS2循环稳定性差的主要原因。本项目针对这一问题，系统研究嵌钠SnS2负极循环过程中Sn粗化的动力学特性及其对Sn/Na2S界面反应活性的影响规律；提出在SnS2-C复合物中添加过渡金属组元M，创建SnS2-MS2异质结构抑制Sn粗化的新策略，阐明(SnM)S2-C中各组员相对电极脱嵌钠可逆性和稳定性的改善作用；引导开发出容量高和长循环稳定的SnS2基负极材料，为推动高容量金属硫化物基嵌钠负极材料的实际应用奠定科学依据和材料基础。

钠离子电池被认为是下一代大规模储能技术的理想选择之一，SnS2具有优异的储钠能力，是一种很有应用前景的负极材料，但是在嵌/脱钠循环过程中存在容量衰减过快的问题。项目负责人研究发现，嵌钠过程中纳米Sn粗化导致的Sn/Na2S转化反应界面减少是SnS2循环稳定性差的主要原因。针对这一问题，项目负责人系统研究了嵌钠SnS2负极循环过程中Sn粗化对其Sn/Na2S界面反应活性的影响规律；提出在SnS2-C复合物中添加过渡金属组元M（Mn或Co），创建SnS2-MS2异质结构，有效地抑制Sn粗化，提高了合金和转化反应可逆性，开发出首效高（90.8%）和长循环稳定（500循环后在5.0 A/g−1电流密度下的可逆比容量为522.5 mAh/g）的SnS2基负极材料，为推动高容量金属硫化物基嵌钠负极材料的实际应用奠定科学依据和材料基础。