关键词: 预镁化, 氧化亚硅, 容量衰减

Abstract:

To improve the electrochemical performance of silicon oxide anode in the full cell, this work takes conventional silicon oxide, pre-magnesium silicon oxide combined with LiNi_xCo_yAl_1-x-yO₂ (NCA) cathode as the full cell and analyzes their mechanism of capacity fading at room temperature and high temperature. Through testing and failure analysis, the structure, composition and surface interface of key materials were obtained. Combined with quantitative analysis, the key factors influencing cell performance were identified. The results indicate that, for both conventional and pre-magnesiated silicon oxide cells, the continuous consumption of active lithium and the formation of a solid electrolyte interface (SEI) film at the anode during cycling are the main reasons for capacity degradation at both room and elevated temperatures. In addition to the instability and continuous growth of the SEI film, the bulk phase structure of the pre-magnesium silicon oxide is unstable in the process of lithium removal, and the particle cracking exposes the new surface, leading to the consumption of more active lithium in the SEI. Therefore, its cycling performance is inferior to that of conventional silicon oxide anode. Although structural degradation (e.g., increased Li/Ni mixing) and impedance rise are also observed at the cathode, the associated capacity loss is primarily constrained by the insufficient available lithium in the system, rather than being the direct cause of full-cell failure. This study provides critical insights from the perspective of interfacial and structural stability, offering important guidance for the design and optimization of high‑initial‑coulombic‑efficiency SiOₓ anode materials and their compatible full cells.

Key words: pre-magnesium, silicon oxide, capacity fading