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Pre-lithiation technology is essential to improve the initial coulombic efficiency (ICE) and cycling stability of high SiO x content cells. Different amounts of pre-lithiation significantly affect the electrochemical performance of cells. In this study, three groups of LiNi 0.8 Co 0.1 Mn 0.1 O 2 || SiO x /Graphite pouch cells (SiO x , 45 wt%) with different pre-lithiation amounts are fabricated using an electrochemical pre-lithium method. The effects of pre-lithiation amounts on the capacity and cycling stability are comprehensively investigated by non-destructive tests and post-mortem analysis. The results show that increasing the amounts of pre-lithiation can substantially improve the capacity of the cells, but may also accelerate their aging. Further studies reveal that the cycling stability of SiOx/Graphite anode is strongly affected by the amounts of pre-lithiation, whereas the effect on the cathode is negligible. Moreover, titration gas chromatography (TGC) experiments are used to quantify the lithium loss in SiO x /Graphite anode. The accelerated formation of SEI and trapped lithiated active materials as well as lithium dendrites caused by over-lithiation at SiO x /Graphite anode are responsible for the rapid degradation of pouch cells with high pre-lithiation amounts. This work demonstrates the complex relationship between pre-lithiation amounts and electrochemical performance, which needs to be carefully measured in SiO x -based cells. [Display omitted] • NCM811||SiO x /Graphite pouch cells with different pre-lithiation amounts are evaluated. • Both ICE and cycle stability is greatly influenced by the pre-lithiation amount. • The amounts of pre-lithiation have little effect on the aging of the cathode. • High pre-lithiation amounts can accelerate anode aging. • Titration gas chromatography is used to quantify the lithium loss in anode. [ABSTRACT FROM AUTHOR]