镓基材料的储钠性能及其自修复机制研究

Alloy-type anode materials for sodium ion battery have attracted tremendous interest for their higher theoretical capacity and safer reaction potential. However, the formation of alloys is always accompanied by huge volume changes, and eventually leads to disintegration of the electrode structure and fast capacity decay upon cycling. Thus, repairing mechanical damage and cracks in the electrode upon cycling is rather desired, resulting in more stable mechanical and electrical connections among the active materials. Gallium (Ga)-based electrodes exhibit self-healing behavior for its liquid nature at room temperature, which can reduce the negative impact of temperature variation. The cracks in electrodes formed upon cycling or at high temperature could be remedied by the solid-liquid transformation of liquid metal Ga. This project aims at the comprehensive investigation on sodium ion storage mechanism of Ga-based materials, elucidating the phase and structure evolution under different state of charge/discharge process. Moreover, the self-healing mechanism was examined by in situ and ex situ tests during the cycles. These results will shed lights on further designing Ga-based materials particularly on self-healing effect, and can be extended to solid-state-battery system.

合金类材料，如锡和锗等，具有容量高和电位平台适宜的优势，是目前钠电池负极的研究热点。但这类材料与钠离子合金化的过程中存在大的体积变化，导致电极产生裂纹，活性物质粉化脱落，严重影响循环稳定性。因此，增强合金类负极的抗裂程度，修复电极片在循环过程出现的裂纹，对改善循环稳定性具有重要意义。针对这些问题，本项目拟选取镓基材料为研究对象，因为金属镓熔点低，其室温液相的特性在充/放电循环过程中具有自愈合的能力。项目拟从镓基材料的储钠机制入手，揭示组分和结构在储钠过程中的演变规律。进一步调制化合物的组分、形貌和结构，研究电化学反应的中间相产物液态镓基材料对电极材料循环过程中所产生裂纹的修复作用，阐明组分、形貌、结构和工作温度与修复作用的内在关联。本项目的研究结果将进一步推进具有自修复机制的电极材料的研究，提高合金型电极材料的循环稳定性。

基于合金机制的储钠材料具有容量高和电位平台适宜的优势，是目前钠电池负极的研究热点。但这类材料与钠离子合金化的过程中存在大的体积变化，导致电极产生裂纹，活性物质粉化脱落，严重影响循环稳定性。因此，增强合金类负极的抗裂程度，修复电极片在循环过程出现的裂纹，对改善循环稳定性具有重要意义。针对这些问题，本项目选取镓基材料为研究对象，因为金属镓熔点低，其室温液相的特性在充/放电循环过程中具有自愈合的能力。项目从镓基材料的储钠机制入手，揭示组分和结构在储钠过程中的演变规律。进一步调制化合物的组分、形貌和结构，研究电化学反应的中间相产物液态镓基材料对电极材料循环过程中所产生裂纹的修复作用，阐明组分、形貌、结构和工作温度与修复作用的内在关联。本项目的研究结果将进一步推进具有自修复机制的电极材料的研究，提高合金型电极材料的循环稳定性。