As a promising next-generation high-capacity anode, the industrial-scale utilization of microsilicon has been hampered by the problem of pulverization in the recycling process. Although numerous studies have demonstrated that modulating the inorganic components in the solid electrolyte interface layer (SEI) is significant in improving its pulverization effect, the evolution of most of the key inorganic components in the SEI and their correlation with silicon failure mechanisms remains ambiguous.
Here, Cui Guanglei's team from the Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, revealed that lithium hydride (LiH) at the solid electrolyte interface (SEI) in the silicon-based anode of lithium-ion batteries is the key factor that causes the accelerated crushing of silicon particles during charging and discharging. Through in-depth analysis and the comprehensive application of various characterization techniques, the authors clarified for the first time the direct correlation between the accumulation of LiH in SEI and the degree of crushing of silicon particles, and proposed a new mechanism, that is, the reverse lithiation behavior of LiH on micron-scale silicon particles during the delithiumation process aggravates the local stress inside the silicon particles and promotes the crushing of the particles.
Figure 1. Evolution of LiH components in SEI during lithium-silicon half-cell cycling
In conclusion, the work found that lithium hydride (LiH), a key component of the solid electrolyte interface (SEI), plays an important role in the morphological evolution of micron-scale silicon anodes. For the first time, the authors reveal a new mechanism by which LiH-induced local lithiation of micron-scale silicon leads to uneven stress distribution and may accelerate micro-silicon crushing. This discovery provides new evidence for the correlation between the intrinsic SEI instability of silicon anodes and the failure of micron-scale silicon anodes, and provides new principles for the scientific design of SEI with high energy density and high stability silicon anodes in the future. That is, by adjusting the LiH content in the electrolyte, the cycling stability of silicon-based cells can be optimized.
Figure 2. . Validation of the reaction of Si with LiH
Lithium Hydride in the Solid Electrolyte Interphase of Lithium-Ion Batteries as a Pulverization Accelerator of Silicon, Angewandte Chemie International Edition 2024 DOI: 10.1002/anie.202406198
Article source: Battery Future
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