Insights into Chemical Prelithiation of SiO x /Graphite Composite Anodes through Scanning Electron Microscope Imaging

InitialCoulombic efficiency (ICE) is critical for determiningthe energy density of lithium-ion batteries (LIBs) used for practicalapplications; however, it is typically disregarded in anode research.We used SiO x and graphite composite anodesfor commercial lithium-ion batteries in our preliminary research toachieve a balance between ICE, capacity, and cycling life. ICE reached88%; however, it needs further improvement for commercial applications.Prelithiation is a process that involves the introduction of extralithium ions into LIBs during their manufacturing to enhance the overallperformance of the LIBs. We applied a chemical prelithiation methodon our SiO x /graphite composite anodes,which comprised 95 wt % of the active material mass loading on theelectrode. The ICE increased from 88% to 98% using an aryllithiumreagent impregnation method within 2 min of prelithiation. The anode'sspecific capacity density, rate, and cycle performance also significantlyimproved. Scanning electron microscopy (SEM) imaging enhanced by anosmium tetroxide staining method indicated that the P-anode containeda stable solid electrolyte interface (SEI) layer after the prelithiationprocess and cycling electrochemical test. The P-anode's stablecharge differential peak over 500 cycles also showcases a robust artificialSEI layer that was generated by the prelithiation procedure. Thisprelithiation process has significant potential for adoption in theLIB industry's current electrode manufacturing process.