多壳层空心结构金属硫化物的可控构建及作为钠离子电池负极材料的性能和储钠机制

The lack of a suitable anode material is a major reason for the difficulty of commercializing sodium ion batteries. Metal sulfide has the advantages of high specific capacity, low cost and easy preparation and it is expected to meet the requirements of sodium ion battery for future energy storage system. However, the metal sulfide shows high potential, low conductivity and poor stability, which prevent its practical application. This project plans to design multi-shelled metal sulfide hollow structures, and improve the sodium storage performances by regulating their composition, structure and surface heterogeneous layer construction. Porous shell and hollow cavity can release the stress generated during the sodium storage and stripping process, thus improve the structural stability and the ion transport efficiency. The shortage of high potential and poor conductivity can be resolved by composition regulation. Maximize the use of possible intercalation, transformation and alloying reaction mechanism for sodium storage can increase the specific capacity. The construction of surface heterogeneous layer can improve the ion and electron transport efficiency, and enhance the material stability. The relationship between composition, structure and storage capacity of metal sulfide will be systematically studied. The mechanism of electrode interface reaction will be discussed based on the experimental results and theoretical simulation. The scientific principle will be explored and revealed. By optimizing the composition and structural design, the multi-shelled metal sulfide hollow structures with low potential and delivery high specific capacity, excellent rate and cycle performance as anode for sodium ion battery will be achieved. The outcome will shed light on the practical application of sodium ion battery and provide theoretical and technical support for similar projects.

缺少合适的负极材料是钠离子电池难以商业化的主要原因之一。金属硫化物具有比容量高、成本低、制备简便等优点，有望成为未来能源存储系统用钠离子电池的负极材料，但其存在电位高，导电性和稳定性差等问题。本项目拟设计具有多壳层空心结构的金属硫化物，调控其组成、结构和构建表面异质层以提高储钠性能。多孔壳层和空心内腔能缓解钠存储与脱出过程产生的应力，提高离子传输效率和结构稳定性，调控组成能解决电位高、导电性差的问题; 从而最大程度利用可能存在的插层、转化和合金化反应储钠机制来获得更高的比容量；构建表面异质层来提高离子和电子传输能力，并增强材料稳定性。本项目将系统研究金属硫化物的组成、结构与储钠性能的关系，结合理论模拟探讨电极界面反应机理，揭示其中的科学原理；总结规律，反馈优化组成与结构设计，最终获得电位低、容量高、倍率性能和循环性能优异的钠离子电池负极材料，为实现钠离子电池的实际应用提供理论和技术支撑。

钠离子电池与锂离子电池有相似的工作原理，主要通过钠离子在正负极之间的嵌入、脱出实现电荷转移。然而，相较锂离子，钠离子体积较大，在材料结构稳定性和动力学性能方面要求更严苛，成为钠离子电池难以商用的瓶颈。本项目针对钠离子电池用电极材料进行了研究。金属硫化物具有丰富的氧化还原中心和电化学活性位点，是一种很有前途的钠离子电池负极材料。但其存在电位高，导电性和稳定性差等问题。本项目通过设计和制备具有多壳层空心结构的金属硫化物，调控其组成、结构和构建表面异质层以提高储钠性能。多孔壳层和空心内腔能缓解钠存储与脱出过程产生的应力，提高离子传输效率和结构稳定性，调控电极材料组成能解决电位高、导电性差的问题，从而最大程度利用存在的插层、转化和合金化反应储钠机制来获得更高的比容量。本项目研究了金属硫化物的组成、结构与储钠性能的关系，探讨了电极界面反应机理，揭示其中的科学原理，最终获得电位低、容量高、倍率性能和循环性能优异的钠离子电池负极材料，为推动钠离子电池的实际应用提供了理论和技术支撑。

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