Pidaparthy Saran, Luo Mei, Rodrigues Marco-Tulio F, Zuo Jian-Min, Abraham Daniel P
Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States of America.
Department of Mechanical, Materials, and Aerospace Engineering, Illinois Institute of Technology, Chicago, Illinois 60616, United States of America.
ACS Appl Mater Interfaces. 2022 Aug 31;14(34):38660-38668. doi: 10.1021/acsami.2c06991. Epub 2022 Aug 16.
The severe capacity fade of lithium-ion cells with silicon-dominant anodes has hindered their widescale commercialization. In this work, we link cell capacity fade to the heterogeneous physicochemical evolution of silicon anodes during battery cycling. Through a multilength scale characterization approach, we demonstrate that silicon particles near the anode surface react differently from those near the copper current collector. In particular, near the anode surface we find an amorphized wispy silicon encased in a highly fluorinated matrix of electrolyte-reduction products. In contrast, closer to the current collector, the silicon retains more of its initial morphology and structure, suggesting the presence of isolated particles. The results show that the accessibility of active silicon to lithium ions varies across the anode matrix. Material and cell designs, which minimize electrode expansion resulting from the in-filling of pores with the solid electrolyte interphase (SEI), are needed to enhance anode homogeneity during the electrochemical cycling.
具有以硅为主的负极的锂离子电池严重的容量衰减阻碍了它们的大规模商业化。在这项工作中，我们将电池容量衰减与电池循环过程中硅负极的非均相物理化学演变联系起来。通过多长度尺度表征方法，我们证明了靠近阳极表面的硅颗粒与靠近铜集流体的硅颗粒反应不同。特别是，在阳极表面附近，我们发现一种非晶态的絮状硅包裹在由电解质还原产物形成的高度氟化的基质中。相比之下，更靠近集流体的硅保留了更多其初始形态和结构，表明存在孤立的颗粒。结果表明，活性硅对锂离子的可及性在整个阳极基质中各不相同。需要进行材料和电池设计，以尽量减少因固体电解质界面（SEI）填充孔隙而导致的电极膨胀，从而在电化学循环过程中提高阳极的均匀性。
