基于稳定化金属锂粉的锂离子电池负极材料预锂化行为及其作用机制研究

The application of electric vehicles was limited owing to the poor endurance of lithium ion battery. It is very important to solve the problem by reducing the irreversible capacity loss and enhancing the cycling stability. Prelithiation of electrode is an effective method to improve the performance. In this project, stabilized lithium metal powder(SLMP) was applied in silicon electrode, and the shell of Li2CO3 was modified. The prelithiation dynamics behavior of electrode was investigated, the formation mechanism of the SEI film formed on the electrode/electrolyte interface was analyzed. Meanwhile, the improving mechanism on the effect of SLMP on electrochemical performance of the electrode was revealed, and the experimental scheme on reducing the irreversible capacity loss and enhancing the cycling stability was proposed. This research will provide the theoretical support and experimental guidance for the efficient application of prelithiation reagent, and it is important to advance the process of the commercial application for the anode materials with high capacity including silicon, Tin, transition metal oxides and so on.

锂离子电池较低的续航能力制约了其在电动汽车的应用，减小电极不可逆容量损失，提高电极循环稳定性能对解决这一问题至关重要。应用稳定化金属锂粉SLMP（Li/Li2CO3核壳结构材料）对电极进行预锂化是改善该性能的有效方式之一。本项目拟将SLMP应用到硅电极中，并对Li2CO3壳层进行修饰改性，探究电极预锂化动力学行为，解析预锂化过程中电极/电解液界面SEI膜成膜机理，从而深入揭示SLMP对电极电化学性能的改善机制，并获取减小不可逆容量损失和提高电极循环稳定性的实验方案。本研究可为预锂化试剂的高效应用提供理论支持和实验帮助，并对推进硅基、锡基及过渡金属氧化物等高容量负极材料的商用应用化进程具有重要的研究意义。

锂离子电池负极材料对电池性能产生至关重要的影响，较大的首次不可逆容量损失和较弱的循环稳定性是制约高容量锂离子电池负极材料商业化应用的重要因素。项目以高容量的硅基材料为研究对象，应用稳定化金属锂粉（SLMP）作为预锂化试剂，优化了预锂化条件，探究了预锂化对电极/电解液界面性质和电极动力学行为的影响，解析了SLMP对电极电化学性能的改善机制，获取了提升电极首次库伦效率，增强电极循环稳定性能的电极预锂化实验方案。结果表明，在实验体系下，采用质量比为2：3的SBR与PS，能确保SLMP具有稳定均匀的分散性，同时也能有效激活SLMP；SLMP加入量为极片材料质量的5/9时，能有效发挥SLMP的活性。电极性能的提升缘于伴随预嵌锂过程，电极表面自发形成了一层离子导电性优良的SEI膜，提高了离子在电极/电解液界面上的传输能力。该研究工作可为预锂化试剂对硅基材料的高效应用提供理论支持和实验帮助，并对推进锡基及过渡金属氧化物等高容量负极材料的应用进程具有重要的借鉴意义。