锂箔预锂对高比能电池体系性能的影响研究

Effect study of Li foil pre-lithiation on high energy density battery

采用高温热平压工艺将超薄金属锂箔与高比容量硅氧负极进行预锂复合,研究不同预锂量(厚度)对首效的影响;搭配不同高镍正极材料体系,制备单层及10Ah级软包电池进行放大验证,并通过EIS阻抗测试、三电极电位分析和SEM-EDS、SS-NMR表征,研究预锂量(厚度)对首次放电容量和循环性能的影响。结果表明,搭配高镍Ni83与超高镍Ni90三元正极材料体系结果相一致,随着预锂量的增加,首次放电容量和首效明显增加,但循环性能随着预锂量的增加而逐步恶化。5μm锂箔预锂后综合性能提升最优,首效提升至93%,200次循环后容量保持率达到93.4%。双面预锂制备10Ah级软包电池,5μm锂箔预锂的首次充放电效率提升至90%以上,15 W恒功率放电表现出与对照组同等的倍率性能,比能量达到360Wh/kg。

Using high temperature pressing technology,ultra-thin lithium metal foil is composited to high specific capacity SiOx negative electrode.To study the effect of different pre-lithiation amounts(thicknesses)on the first coulombic efficiency,the initial discharge capacity and cycling performance,single-layer and 10 Ah-level pouch cells are prepared to amplified verification combining different high nickel cathode material systems,through EIS impedance test,three electrodes potential analysis,and SEM-EDS,SS-NMR characterization.The results show that,with the increase of pre-lithiation amount,the first efficiency significantly increase,but the cycling performance gradually deteriorates,collocating both the high nickel Ni83 and ultra-high nickel Ni90 cathode material systems.5μm Li-foil pre-lithiation has the optimal performance among all plans,with the first efficiency increased to 93%,and the capacity retention rate reached 93.4%after 200 cycles.Furtherly,double-side lithium foil pre-lithiation is used to prepare 10 Ah-level pouch cell.The initial efficiency of 5μm Li-foil pre-lithium cell improve to over 90%,and the 15 W constant power discharge shows the same rate performance as the base group,finally the energy density reaches 360 Wh/kg。